WorldWideScience

Sample records for spectral region based

  1. Characterizing CDOM Spectral Variability Across Diverse Regions and Spectral Ranges

    Science.gov (United States)

    Grunert, Brice K.; Mouw, Colleen B.; Ciochetto, Audrey B.

    2018-01-01

    Satellite remote sensing of colored dissolved organic matter (CDOM) has focused on CDOM absorption (aCDOM) at a reference wavelength, as its magnitude provides insight into the underwater light field and large-scale biogeochemical processes. CDOM spectral slope, SCDOM, has been treated as a constant or semiconstant parameter in satellite retrievals of aCDOM despite significant regional and temporal variabilities. SCDOM and other optical metrics provide insights into CDOM composition, processing, food web dynamics, and carbon cycling. To date, much of this work relies on fluorescence techniques or aCDOM in spectral ranges unavailable to current and planned satellite sensors (e.g., global variability in SCDOM and fit deviations in the aCDOM spectra using the recently proposed Gaussian decomposition method. From this, we investigate if global variability in retrieved SCDOM and Gaussian components is significant and regionally distinct. We iteratively decreased the spectral range considered and analyzed the number, location, and magnitude of fitted Gaussian components to understand if a reduced spectral range impacts information obtained within a common spectral window. We compared the fitted slope from the Gaussian decomposition method to absorption-based indices that indicate CDOM composition to determine the ability of satellite-derived slope to inform the analysis and modeling of large-scale biogeochemical processes. Finally, we present implications of the observed variability for remote sensing of CDOM characteristics via SCDOM.

  2. A rhodamine–dansyl conjugate as a FRET based sensor for Fe{sup 3+} in the red spectral region

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Puhui, E-mail: pxie2007@yahoo.com.cn [College of Sciences, Henan Agricultural University, Zhengzhou 450002 (China); Guo, Fengqi, E-mail: fqguo@zzu.edu.cn [College of Chemistry and Molecular Engineering, Zhengzhou University, Zhengzhou 450001 (China); Xia, Ruirui; Wang, Yao [College of Sciences, Henan Agricultural University, Zhengzhou 450002 (China); Yao, Denghui [College of Chemistry and Molecular Engineering, Zhengzhou University, Zhengzhou 450001 (China); Yang, Guoyu; Xie, Lixia [College of Sciences, Henan Agricultural University, Zhengzhou 450002 (China)

    2014-01-15

    A new fluorescent resonance energy transfer (FRET) based fluorescent probe (compound 1) containing a dansyl unit as a donor and rhodamine 101 as an acceptor was developed to detect Fe{sup 3+} from other transition metal ions through ratiometric sensing in organic-aqueous solutions. Fe{sup 3+} induced a ring-opening reaction of the spirolactam rhodamine moiety of 1 resulting in the formation of a fluorescent derivative that can serve as the FRET acceptor. Ratiometric sensing of Fe{sup 3+} was accomplished by plotting the fluorescence intensity ratio at 605 nm and 515 nm versus ferric ion concentration. The probe displayed a linear response to Fe{sup 3+} in the range of 5.5–25 μM with a detection limit of 0.64 μM. A 1:1 stoichiometry for the 1–Fe{sup 3+} complex was formed with an association constant of 1.74×10{sup 4} M{sup −1}. The probe also exhibited a large Stokes shift (225 nm) which can eliminate backscattering effects of excitation light. -- Highlights: • A new colorimetric and fluorescent “off–on” chemosensor for Fe{sup 3+} was synthesized. • It can respond to Fe{sup 3+} in the red spectral region based on a FRET mechanism. • Its ratiometric sensing for Fe{sup 3+} can be accomplished with a signal to noise ratio of 214. • The large Stokes shift (225 nm) can rule out the excitation backscattering effects.

  3. Use of the vacuum ultraviolet spectral region for laser-induced breakdown spectroscopy-based Martian geology and exploration

    International Nuclear Information System (INIS)

    Radziemski, Leon; Cremers, David A.; Benelli, Katharine; Khoo, Cynthia; Harris, Ronny D.

    2005-01-01

    Several elements important to planetary geology (e.g. Br, C, Cl, P, S) and the human exploration of Mars (e.g. toxic elements such as As) have strong emission lines in the purge and vacuum ultraviolet (VUV) spectral region (100-200 nm). This spectral region has not been extensively studied for space applications using geological samples. We studied emissions from the laser-induced breakdown spectroscopy (LIBS) plasma in this region using a sample chamber filled with 7 torr (930 Pa) of CO 2 to simulate the Martian atmosphere. Pressures down to 0.02 torr were also used to evaluate the effect of the residual CO 2 on the spectra and to begin investigating the use of VUV-LIBS for airless bodies such as asteroids and the Moon. Spectra were recorded using a 0.3-m vacuum spectrometer with an intensified CCD (ICCD) camera. The effects of time delay and laser energy on LIBS detection at reduced pressure were examined. The effect of ambient CO 2 on the detection of C in soil was also evaluated. Lines useful for the spectrochemical analysis of As, Br, C, Cl, P, and S were determined and calibration curves were prepared for these elements. Although LIBS is being developed for stand-off analysis at many meters distance, the experiments reported here were aimed at in-situ (close-up) analysis

  4. Pulsed, all solid-state light source in the visible spectral region based on non-linear cavity dumping

    DEFF Research Database (Denmark)

    Tidemand-Lichtenberg, Peter; Andersen, Martin; Johansson, Sandra

    We propose a novel generic approach for generation of pulsed light in the visible spectrum, based on SFG between the high circulating intra-cavity power of a high finesse CW laser and a single-passed pulsed laser.......We propose a novel generic approach for generation of pulsed light in the visible spectrum, based on SFG between the high circulating intra-cavity power of a high finesse CW laser and a single-passed pulsed laser....

  5. On global and regional spectral evaluation of global geopotential models

    International Nuclear Information System (INIS)

    Ustun, A; Abbak, R A

    2010-01-01

    Spectral evaluation of global geopotential models (GGMs) is necessary to recognize the behaviour of gravity signal and its error recorded in spherical harmonic coefficients and associated standard deviations. Results put forward in this wise explain the whole contribution of gravity data in different kinds that represent various sections of the gravity spectrum. This method is more informative than accuracy assessment methods, which use external data such as GPS-levelling. Comparative spectral evaluation for more than one model can be performed both in global and local sense using many spectral tools. The number of GGMs has grown with the increasing number of data collected by the dedicated satellite gravity missions, CHAMP, GRACE and GOCE. This fact makes it necessary to measure the differences between models and to monitor the improvements in the gravity field recovery. In this paper, some of the satellite-only and combined models are examined in different scales, globally and regionally, in order to observe the advances in the modelling of GGMs and their strengths at various expansion degrees for geodetic and geophysical applications. The validation of the published errors of model coefficients is a part of this evaluation. All spectral tools explicitly reveal the superiority of the GRACE-based models when compared against the models that comprise the conventional satellite tracking data. The disagreement between models is large in local/regional areas if data sets are different, as seen from the example of the Turkish territory

  6. Mapping Distinct Forest Types Improves Overall Forest Identification Based on Multi-Spectral Landsat Imagery for Myanmar’s Tanintharyi Region

    Directory of Open Access Journals (Sweden)

    Grant Connette

    2016-10-01

    Full Text Available We investigated the use of multi-spectral Landsat OLI imagery for delineating mangrove, lowland evergreen, upland evergreen and mixed deciduous forest types in Myanmar’s Tanintharyi Region and estimated the extent of degraded forest for each unique forest type. We mapped a total of 16 natural and human land use classes using both a Random Forest algorithm and a multivariate Gaussian model while considering scenarios with all natural forest classes grouped into a single intact or degraded category. Overall, classification accuracy increased for the multivariate Gaussian model with the partitioning of intact and degraded forest into separate forest cover classes but slightly decreased based on the Random Forest classifier. Natural forest cover was estimated to be 80.7% of total area in Tanintharyi. The most prevalent forest types are upland evergreen forest (42.3% of area and lowland evergreen forest (21.6%. However, while just 27.1% of upland evergreen forest was classified as degraded (on the basis of canopy cover <80%, 66.0% of mangrove forest and 47.5% of the region’s biologically-rich lowland evergreen forest were classified as degraded. This information on the current status of Tanintharyi’s unique forest ecosystems and patterns of human land use is critical to effective conservation strategies and land-use planning.

  7. Maximum spectral demands in the near-fault region

    Science.gov (United States)

    Huang, Yin-Nan; Whittaker, Andrew S.; Luco, Nicolas

    2008-01-01

    The Next Generation Attenuation (NGA) relationships for shallow crustal earthquakes in the western United States predict a rotated geometric mean of horizontal spectral demand, termed GMRotI50, and not maximum spectral demand. Differences between strike-normal, strike-parallel, geometric-mean, and maximum spectral demands in the near-fault region are investigated using 147 pairs of records selected from the NGA strong motion database. The selected records are for earthquakes with moment magnitude greater than 6.5 and for closest site-to-fault distance less than 15 km. Ratios of maximum spectral demand to NGA-predicted GMRotI50 for each pair of ground motions are presented. The ratio shows a clear dependence on period and the Somerville directivity parameters. Maximum demands can substantially exceed NGA-predicted GMRotI50 demands in the near-fault region, which has significant implications for seismic design, seismic performance assessment, and the next-generation seismic design maps. Strike-normal spectral demands are a significantly unconservative surrogate for maximum spectral demands for closest distance greater than 3 to 5 km. Scale factors that transform NGA-predicted GMRotI50 to a maximum spectral demand in the near-fault region are proposed.

  8. Euler deconvolution and spectral analysis of regional aeromagnetic ...

    African Journals Online (AJOL)

    Existing regional aeromagnetic data from the south-central Zimbabwe craton has been analysed using 3D Euler deconvolution and spectral analysis to obtain quantitative information on the geological units and structures for depth constraints on the geotectonic interpretation of the region. The Euler solution maps confirm ...

  9. Ratioing methods for in-flight response calibration of space-based spectro-radiometers, operating in the solar spectral region

    Science.gov (United States)

    Lobb, Dan

    2017-11-01

    One of the most significant problems for space-based spectro-radiometer systems, observing Earth from space in the solar spectral band (UV through short-wave IR), is in achievement of the required absolute radiometric accuracy. Classical methods, for example using one or more sun-illuminated diffusers as reflectance standards, do not generally provide methods for monitoring degradation of the in-flight reference after pre-flight characterisation. Ratioing methods have been proposed that provide monitoring of degradation of solar attenuators in flight, thus in principle allowing much higher confidence in absolute response calibration. Two example methods are described. It is shown that systems can be designed for relatively low size and without significant additions to the complexity of flight hardware.

  10. Spectral density of electron concentration fluctuations in ionospheric D region

    International Nuclear Information System (INIS)

    Martynenko, S.I.

    1989-01-01

    Expression for spectral density of electron concentration fluctuations in D-region with regard to the effect of ionization-recombination proceses and negative ions is obtained in terms of atmospheric turbulence model which obeys Kolmogorov-Obukhov 2/3 law

  11. Spectral Irradiance Measurements Based on Detector

    International Nuclear Information System (INIS)

    Lima, M S; Menegotto, T; Duarte, I; Da Silva, T Ferreira; Alves, L C; Alvarenga, A D; Almeida, G B; Couceiro, I B; Teixeira, R N

    2015-01-01

    This paper presents the preliminary results of the realization of absolute spectral irradiance scale at INMETRO in the ultraviolet, visible and infrared regions using filter radiometers as secondary standards. In the construction of these instruments are used, at least, apertures, interference filters and a trap detector. In the assembly of the trap detectors it was necessary to characterize several photocells in spatial uniformity and shunt resistance. All components were calibrated and these results were analyzed to mount the filter radiometer

  12. Soil classification basing on the spectral characteristics of topsoil samples

    Science.gov (United States)

    Liu, Huanjun; Zhang, Xiaokang; Zhang, Xinle

    2016-04-01

    Soil taxonomy plays an important role in soil utility and management, but China has only course soil map created based on 1980s data. New technology, e.g. spectroscopy, could simplify soil classification. The study try to classify soils basing on the spectral characteristics of topsoil samples. 148 topsoil samples of typical soils, including Black soil, Chernozem, Blown soil and Meadow soil, were collected from Songnen plain, Northeast China, and the room spectral reflectance in the visible and near infrared region (400-2500 nm) were processed with weighted moving average, resampling technique, and continuum removal. Spectral indices were extracted from soil spectral characteristics, including the second absorption positions of spectral curve, the first absorption vale's area, and slope of spectral curve at 500-600 nm and 1340-1360 nm. Then K-means clustering and decision tree were used respectively to build soil classification model. The results indicated that 1) the second absorption positions of Black soil and Chernozem were located at 610 nm and 650 nm respectively; 2) the spectral curve of the meadow is similar to its adjacent soil, which could be due to soil erosion; 3) decision tree model showed higher classification accuracy, and accuracy of Black soil, Chernozem, Blown soil and Meadow are 100%, 88%, 97%, 50% respectively, and the accuracy of Blown soil could be increased to 100% by adding one more spectral index (the first two vole's area) to the model, which showed that the model could be used for soil classification and soil map in near future.

  13. Regional Spectral Model simulations of the summertime regional climate over Taiwan and adjacent areas

    Science.gov (United States)

    Ching-Teng Lee; Ming-Chin Wu; Shyh-Chin Chen

    2005-01-01

    The National Centers for Environmental Prediction (NCEP) regional spectral model (RSM) version 97 was used to investigate the regional summertime climate over Taiwan and adjacent areas for June-July-August of 1990 through 2000. The simulated sea-level-pressure and wind fields of RSM1 with 50-km grid space are similar to the reanalysis, but the strength of the...

  14. Selective suppression of high-order harmonics within phase-matched spectral regions.

    Science.gov (United States)

    Lerner, Gavriel; Diskin, Tzvi; Neufeld, Ofer; Kfir, Ofer; Cohen, Oren

    2017-04-01

    Phase matching in high-harmonic generation leads to enhancement of multiple harmonics. It is sometimes desired to control the spectral structure within the phase-matched spectral region. We propose a scheme for selective suppression of high-order harmonics within the phase-matched spectral region while weakly influencing the other harmonics. The method is based on addition of phase-mismatched segments within a phase-matched medium. We demonstrate the method numerically in two examples. First, we show that one phase-mismatched segment can significantly suppress harmonic orders 9, 15, and 21. Second, we show that two phase-mismatched segments can efficiently suppress circularly polarized harmonics with one helicity over the other when driven by a bi-circular field. The new method may be useful for various applications, including the generation of highly helical bright attosecond pulses.

  15. Spectrally based mapping of riverbed composition

    Science.gov (United States)

    Legleiter, Carl; Stegman, Tobin K.; Overstreet, Brandon T.

    2016-01-01

    Remote sensing methods provide an efficient means of characterizing fluvial systems. This study evaluated the potential to map riverbed composition based on in situ and/or remote measurements of reflectance. Field spectra and substrate photos from the Snake River, Wyoming, USA, were used to identify different sediment facies and degrees of algal development and to quantify their optical characteristics. We hypothesized that accounting for the effects of depth and water column attenuation to isolate the reflectance of the streambed would enhance distinctions among bottom types and facilitate substrate classification. A bottom reflectance retrieval algorithm adapted from coastal research yielded realistic spectra for the 450 to 700 nm range; but bottom reflectance-based substrate classifications, generated using a random forest technique, were no more accurate than classifications derived from above-water field spectra. Additional hypothesis testing indicated that a combination of reflectance magnitude (brightness) and indices of spectral shape provided the most accurate riverbed classifications. Convolving field spectra to the response functions of a multispectral satellite and a hyperspectral imaging system did not reduce classification accuracies, implying that high spectral resolution was not essential. Supervised classifications of algal density produced from hyperspectral data and an inferred bottom reflectance image were not highly accurate, but unsupervised classification of the bottom reflectance image revealed distinct spectrally based clusters, suggesting that such an image could provide additional river information. We attribute the failure of bottom reflectance retrieval to yield more reliable substrate maps to a latent correlation between depth and bottom type. Accounting for the effects of depth might have eliminated a key distinction among substrates and thus reduced discriminatory power. Although further, more systematic study across a broader

  16. Spectral Comparison and Stability of Red Regions on Jupiter

    Science.gov (United States)

    Simon, A. A.; Carlson, R. W.; Sanchez-Lavega, A.

    2013-01-01

    A study of absolute color on Jupiter from Hubble Space Telescope imaging data shows that the Great Red Spot (GRS) is not the reddest region of the planet. Rather, a transient red cyclone visible in 1995 and the North Equatorial Belt both show redder spectra than the GRS (i.e., more absorption at blue and green wavelengths). This cyclone is unique among vortices in that it is intensely colored yet low altitude, unlike the GRS. Temporal analysis shows that the darkest regions of the NEB are relative constant in color from 1995 to 2008, while the slope of the GRS core may vary slightly. Principal component analysis shows several spectral components are needed, in agreement with past work, and further highlights the differences between regions. These color differences may be indicative of the same chromophore(s) under different conditions, such as mixing with white clouds, longer UV irradiation at higher altitude, and thermal processing, or may indicate abundance variations in colored compounds. A single compound does not fit the spectrum of any region well and mixes of multiple compounds including NH4SH, photolyzed NH3, hydrocarbons, and possibly P4, are likely needed to fully match each spectrum.

  17. Spectral emissivity of tungsten: analytic expressions for the 340-nm to 2.6-μm spectral region

    International Nuclear Information System (INIS)

    Pon, R.M.; Hessler, J.P.

    1984-01-01

    To correct emission spectra a standard radiance source is often used to determine the spectral responsivity of the detection system. In the near-UV, visible, and near-IR spectral regions the most common radiance standard is a tungsten strip lamp calibrated by a standards laboratory. For day-to-day experiments where slightly less accuracy is acceptable, a less expensive uncalibrated lamp is useful. In this case, the radiant temperature T/sub r/ of the lamp is measured with an optical pyrometer, generally at a single wavelength such as 650 nm, and the source spectral radiance L(λ) is calculated from L(λ) = tau(λ)epsilon(λ,T)L/sub B/(λ,T). The transmittance of the source is tau(λ), the spectral emissivity is epsilon(λ,T), and L/sub B/(λ,T) is the spectral distribution of blackbody radiation, Planck's radiation law. To obtain the true temperature T, Wien's approximation is employed. To conveniently calibrate a system, especially one which utilizes a microcomputer, it is advantageous to have analytic expressions for the spectral emissivity of tungsten. Although Larrabee has published such expressions, they are limited to the 450-800-nm spectral region. To obtain analytic expressions from 340 nm to 2.6 μm they have used the measurements of DeVos. Although DeVos's results differ by 2% from those of Larrabee, this difference is assumed to be acceptable

  18. Toward an Empirically-based Parametric Explosion Spectral Model

    Science.gov (United States)

    Ford, S. R.; Walter, W. R.; Ruppert, S.; Matzel, E.; Hauk, T. F.; Gok, R.

    2010-12-01

    Small underground nuclear explosions need to be confidently detected, identified, and characterized in regions of the world where they have never occurred. We develop a parametric model of the nuclear explosion seismic source spectrum derived from regional phases (Pn, Pg, and Lg) that is compatible with earthquake-based geometrical spreading and attenuation. Earthquake spectra are fit with a generalized version of the Brune spectrum, which is a three-parameter model that describes the long-period level, corner-frequency, and spectral slope at high-frequencies. These parameters are then correlated with near-source geology and containment conditions. There is a correlation of high gas-porosity (low strength) with increased spectral slope. However, there are trade-offs between the slope and corner-frequency, which we try to independently constrain using Mueller-Murphy relations and coda-ratio techniques. The relationship between the parametric equation and the geologic and containment conditions will assist in our physical understanding of the nuclear explosion source, and aid in the prediction of observed local and regional distance seismic amplitudes for event identification and yield determination in regions with incomplete or no prior history of underground nuclear testing.

  19. Hungaria Asteroid Region Telescopic Spectral Survey (HARTSS): Stony Asteroids Abundant in the Background and Family Populations

    Science.gov (United States)

    Lucas, Michael P.; Emery, Joshua P.; Pinilla-Alonso, Noemi; Lindsay, Sean S.; Lorenzi, Vania

    2016-10-01

    The Hungaria region represents a "purgatory" for the closest, preserved samples of the material from which the terrestrial planets accreted. The Hungaria region harbors a collisional family of Xe-type asteroids, which are situated among a background of predominantly S-complex asteroids. Deciphering their surface composition may provide constraints on the nature of the primordial building blocks of the terrestrial planets. We hypothesize that planetesimals in the inner part of the primordial asteroid belt experienced partial- to full-melting and differentiation, the Hungaria region should retain any petrologically-evolved material that formed there.We have undertaken an observational campaign entitled the Hungaria Asteroid Region Telescopic Spectral Survey (HARTSS) to record near-infrared (NIR) spectra to characterize taxonomy, surface mineralogy, and potential meteorite analogs. We used NIR instruments at two ground-based facilities (NASA IRTF; TNG). Our data set includes spectra of 82 Hungaria asteroids (61 background; 21 family), 65 were observed during HARTSS. We compare S-complex background asteroids to calibrations developed via laboratory analyses of ordinary chondrites, and to our analyses (EPMA, XRD, VIS+NIR spectra) of 11 primitive achondrite (acapulcoite-lodranite clan) meteorites.We find that stony S-complex asteroids dominate the Hungaria background population (~80%). Background objects exhibit considerable spectral diversity, when quantified by spectral band parameter measurements, translates to a variety of surface compositions. Two main meteorite groups are represented within the Hungaria background: unmelted, nebular L chondrites (and/or L chondrites), and partially-melted primitive achondrites. H-chondrite mineralogies appear to be absent from the Hungaria background. Xe-type Hungaria family members exhibit spectral homogeneity, consistent with the hypothesis that the family was derived from the disruption of a parent body analogous to an enstatite

  20. Properties of magnetic photonic crystals in the visible spectral region and their performance limitations

    Science.gov (United States)

    Kotov, V. A.; Shavrov, V. G.; Vasiliev, M.; Alameh, K.; Nur-E-Alam, M.; Balabanov, D. E.

    2018-02-01

    We report on the results of computer modelling and performance analysis of the optical and magneto-optical (MO) characteristics of one-dimensional magnetic photonic crystals (MPC) of several classic design types (having either a single structure defect, or a number of these), designed for applications in the visible spectral region. The calculations are performed accounting for the real levels of optical absorption achievable in existing MO materials which currently demonstrate the best MO quality (bismuth-substituted ferrite garnets). We consider Bi2Dy1Fe4Ga1O12 as the base material for use within quarter-wave thick MO layers of MPC; silica is used for the non-magnetic transparent quarter-wave layers. The achieved results can be used to clarify the nature of the differences that exist between the expected practical potential of MPCs in integrated photonics, and the actual attained experimental results. Our results show that in MPCs optimized for light intensity modulation applications, in the red spectral region (near 650 nm), the achievable levels of optical transmission are limited to about 30%. This coincides spectrally with the peaks of Faraday rotation reaching their maxima at about 25°, with further transmission increases possible in the near-infrared region. Larger Faraday rotation angles are only achievable currently in structures or single film layers with reduced transmission.

  1. Radiation from an equilibrium CO2-N2 plasma in the [250-850 nm] spectral region: II. Spectral modelling

    International Nuclear Information System (INIS)

    Silva, M Lino da; Vacher, D; Andre, P; Faure, G; Dudeck, M

    2008-01-01

    In the first part of this work, described in a previous paper, the thermodynamic conditions in an atmospheric pressure inductively coupled CO 2 -N 2 plasma have been determined, and the radiation emission spectrum has been measured and calibrated in the [250-850 nm] spectral region. In the second part of this work, a synthetic radiation spectrum is obtained taking into account (a) the geometry of the plasma torch and (b) the local thermodynamic conditions of the plasma. This synthetic spectrum has then been compared against the measured spectrum. The good agreement between the two spectra allows validating the spectral database of the line-by-line code SPARTAN for the simulation of the radiative emission of CO 2 -N 2 plasmas from the near-UV to the near-IR spectral region.

  2. Development of a Fast and Accurate PCRTM Radiative Transfer Model in the Solar Spectral Region

    Science.gov (United States)

    Liu, Xu; Yang, Qiguang; Li, Hui; Jin, Zhonghai; Wu, Wan; Kizer, Susan; Zhou, Daniel K.; Yang, Ping

    2016-01-01

    A fast and accurate principal component-based radiative transfer model in the solar spectral region (PCRTMSOLAR) has been developed. The algorithm is capable of simulating reflected solar spectra in both clear sky and cloudy atmospheric conditions. Multiple scattering of the solar beam by the multilayer clouds and aerosols are calculated using a discrete ordinate radiative transfer scheme. The PCRTM-SOLAR model can be trained to simulate top-of-atmosphere radiance or reflectance spectra with spectral resolution ranging from 1 cm(exp -1) resolution to a few nanometers. Broadband radiances or reflectance can also be calculated if desired. The current version of the PCRTM-SOLAR covers a spectral range from 300 to 2500 nm. The model is valid for solar zenith angles ranging from 0 to 80 deg, the instrument view zenith angles ranging from 0 to 70 deg, and the relative azimuthal angles ranging from 0 to 360 deg. Depending on the number of spectral channels, the speed of the current version of PCRTM-SOLAR is a few hundred to over one thousand times faster than the medium speed correlated-k option MODTRAN5. The absolute RMS error in channel radiance is smaller than 10(exp -3) mW/cm)exp 2)/sr/cm(exp -1) and the relative error is typically less than 0.2%.

  3. Spectral Efficiency Analysis for Multicarrier Based 4G Systems

    DEFF Research Database (Denmark)

    Silva, Nuno; Rahman, Muhammad Imadur; Frederiksen, Flemming Bjerge

    2006-01-01

    In this paper, a spectral efficiency definition is proposed. Spectral efficiency for multicarrier based multiaccess techniques, such as OFDMA, MC-CDMA and OFDMA-CDM, is analyzed. Simulations for different indoor and outdoor scenarios are carried out. Based on the simulations, we have discussed ho...

  4. Quantum BCH Codes Based on Spectral Techniques

    International Nuclear Information System (INIS)

    Guo Ying; Zeng Guihua

    2006-01-01

    When the time variable in quantum signal processing is discrete, the Fourier transform exists on the vector space of n-tuples over the Galois field F 2 , which plays an important role in the investigation of quantum signals. By using Fourier transforms, the idea of quantum coding theory can be described in a setting that is much different from that seen that far. Quantum BCH codes can be defined as codes whose quantum states have certain specified consecutive spectral components equal to zero and the error-correcting ability is also described by the number of the consecutive zeros. Moreover, the decoding of quantum codes can be described spectrally with more efficiency.

  5. Spectral classifying base on color of live corals and dead corals covered with algae

    Science.gov (United States)

    Nurdin, Nurjannah; Komatsu, Teruhisa; Barille, Laurent; Akbar, A. S. M.; Sawayama, Shuhei; Fitrah, Muh. Nur; Prasyad, Hermansyah

    2016-05-01

    Pigments in the host tissues of corals can make a significant contribution to their spectral signature and can affect their apparent color as perceived by a human observer. The aim of this study is classifying the spectral reflectance of corals base on different color. It is expected that they can be used as references in discriminating between live corals, dead coral covered with algae Spectral reflectance data was collected in three small islands, Spermonde Archipelago, Indonesia by using a hyperspectral radiometer underwater. First and second derivative analysis resolved the wavelength locations of dominant features contributing to reflectance in corals and support the distinct differences in spectra among colour existed. Spectral derivative analysis was used to determine the specific wavelength regions ideal for remote identification of substrate type. The analysis results shown that yellow, green, brown and violet live corals are spectrally separable from each other, but they are similar with dead coral covered with algae spectral.

  6. EYE REGIONALIZATION AND SPECTRAL TUNING OF RETINAL PIGMENTS IN INSECTS

    NARCIS (Netherlands)

    STAVENGA, DG

    The spatial and spectral properties of an eye can often be directly linked to the behaviour and habitat of the animal. In a honey bee (Apis mellifera) society, the drones use the well-developed dorsal part of the eye to detect the queen against the sky during her nuptial flight. Recently it has

  7. A classification of spectral populations observed in HF radar backscatter from the E region auroral electrojets

    Directory of Open Access Journals (Sweden)

    S. E. Milan

    2001-02-01

    Full Text Available Observations of HF radar backscatter from the auroral electrojet E region indicate the presence of five major spectral populations, as opposed to the two predominant spectral populations, types I and II, observed in the VHF regime. The Doppler shift, spectral width, backscatter power, and flow angle dependencies of these five populations are investigated and described. Two of these populations are identified with type I and type II spectral classes, and hence, are thought to be generated by the two-stream and gradient drift instabilities, respectively. The remaining three populations occur over a range of velocities which can greatly exceed the ion acoustic speed, the usual limiting velocity in VHF radar observations of the E region. The generation of these spectral populations is discussed in terms of electron density gradients in the electrojet region and recent non-linear theories of E region irregularity generation.Key words. Ionosphere (ionospheric irregularities

  8. A classification of spectral populations observed in HF radar backscatter from the E region auroral electrojets

    Directory of Open Access Journals (Sweden)

    S. E. Milan

    Full Text Available Observations of HF radar backscatter from the auroral electrojet E region indicate the presence of five major spectral populations, as opposed to the two predominant spectral populations, types I and II, observed in the VHF regime. The Doppler shift, spectral width, backscatter power, and flow angle dependencies of these five populations are investigated and described. Two of these populations are identified with type I and type II spectral classes, and hence, are thought to be generated by the two-stream and gradient drift instabilities, respectively. The remaining three populations occur over a range of velocities which can greatly exceed the ion acoustic speed, the usual limiting velocity in VHF radar observations of the E region. The generation of these spectral populations is discussed in terms of electron density gradients in the electrojet region and recent non-linear theories of E region irregularity generation.

    Key words. Ionosphere (ionospheric irregularities

  9. Spectral features based tea garden extraction from digital orthophoto maps

    Science.gov (United States)

    Jamil, Akhtar; Bayram, Bulent; Kucuk, Turgay; Zafer Seker, Dursun

    2018-05-01

    The advancements in the photogrammetry and remote sensing technologies has made it possible to extract useful tangible information from data which plays a pivotal role in various application such as management and monitoring of forests and agricultural lands etc. This study aimed to evaluate the effectiveness of spectral signatures for extraction of tea gardens from 1 : 5000 scaled digital orthophoto maps obtained from Rize city in Turkey. First, the normalized difference vegetation index (NDVI) was derived from the input images to suppress the non-vegetation areas. NDVI values less than zero were discarded and the output images was normalized in the range 0-255. Individual pixels were then mapped into meaningful objects using global region growing technique. The resulting image was filtered and smoothed to reduce the impact of noise. Furthermore, geometrical constraints were applied to remove small objects (less than 500 pixels) followed by morphological opening operator to enhance the results. These objects served as building blocks for further image analysis. Finally, for the classification stage, a range of spectral values were empirically calculated for each band and applied on candidate objects to extract tea gardens. For accuracy assessment, we employed an area based similarity metric by overlapping obtained tea garden boundaries with the manually digitized tea garden boundaries created by experts of photogrammetry. The overall accuracy of the proposed method scored 89 % for tea gardens from 10 sample orthophoto maps. We concluded that exploiting the spectral signatures using object based analysis is an effective technique for extraction of dominant tree species from digital orthophoto maps.

  10. Spectral Imaging by Upconversion

    DEFF Research Database (Denmark)

    Dam, Jeppe Seidelin; Pedersen, Christian; Tidemand-Lichtenberg, Peter

    2011-01-01

    We present a method to obtain spectrally resolved images using upconversion. By this method an image is spectrally shifted from one spectral region to another wavelength. Since the process is spectrally sensitive it allows for a tailored spectral response. We believe this will allow standard...... silicon based cameras designed for visible/near infrared radiation to be used for spectral images in the mid infrared. This can lead to much lower costs for such imaging devices, and a better performance....

  11. Optimization of spectral printer modeling based on a modified cellular Yule-Nielsen spectral Neugebauer model.

    Science.gov (United States)

    Liu, Qiang; Wan, Xiaoxia; Xie, Dehong

    2014-06-01

    The study presented here optimizes several steps in the spectral printer modeling workflow based on a cellular Yule-Nielsen spectral Neugebauer (CYNSN) model. First, a printer subdividing method was developed that reduces the number of sub-models while maintaining the maximum device gamut. Second, the forward spectral prediction accuracy of the CYNSN model for each subspace of the printer was improved using back propagation artificial neural network (BPANN) estimated n values. Third, a sequential gamut judging method, which clearly reduced the complexity of the optimal sub-model and cell searching process during printer backward modeling, was proposed. After that, we further modified the use of the modeling color metric and comprehensively improved the spectral and perceptual accuracy of the spectral printer model. The experimental results show that the proposed optimization approaches provide obvious improvements in aspects of the modeling accuracy or efficiency for each of the corresponding steps, and an overall improvement of the optimized spectral printer modeling workflow was also demonstrated.

  12. Selection/extraction of spectral regions for autofluorescence spectra measured in the oral cavity

    NARCIS (Netherlands)

    Skurichina, M; Paclik, P; Duin, RPW; de Veld, D; Sterenborg, HJCM; Witjes, MJH; Roodenburg, JLN; Fred, A; Caelli, T; Duin, RPW; Campilho, A; DeRidder, D

    2004-01-01

    Recently a number of successful algorithms to select/extract discriminative spectral regions was introduced. These methods may be more beneficial than the standard feature selection/extraction methods for spectral classification. In this paper, on the example of autofluorescence spectra measured in

  13. Spectral curves of surface reflectance in some Antarctic regions

    International Nuclear Information System (INIS)

    Lupi, A.; Tomasi, C.; Orsini, A.; Cacciari, A.; Vitale, V.; Georgiadis, T.; Casacchia, R.; Salvatori, R.; Salvi, S.

    2001-01-01

    Four surface reflectance models of solar radiation were determined by examining several sets of field measurements taken for clear-sky conditions at various sites in Antarctica. Each model consists of the mean spectral curve of surface reflectance in the 0.25-2.7 μm wavelength range and of the dependence curve of total abedo on the solar elevation angle h, within the range from 5 0 to 55 0 . The TNB (Terra Nova Bay) model refers to a rocky terrain where granites are predominant; the NIS (Nansen Ice Sheet) model to a glacier surface made uneven by sastrugi and streaked by irregular fractures; the HAP (High Altitude Plateau) model to a flat ice surface covered by fresh snow and scored by light sastrugi; and the RIS (Ross Ice Shelf) model to an area covered by the sea ice pack presenting many discontinuities in the reflectance features, due to melt water lakes, puddles, refrozen ice and snow pots. The reflectance curve obtained for the TNB model presents gradually increasing values as wavelength increases through the visible spectral range and almost constant values at infrared wavelengths, giving a total albedo value equal to 0.264 at = 30 0 , which increases by about 80% through the lower range of h and decreases by 12% through the upper range. The reflectance curves of the NIS, HAP and RIS models are all peaked at visible wavelengths and exhibit decreasing values throughout the infrared spectral range, giving values of total albedo equal to 0.464, 0.738 and 0.426 at h 30 0 , respectively. These values were estimated to increase by 8-14% as h decreases from 30 0 to 5 0 and to decrease by 2-4% only as h increases from 30 0 to 55 0

  14. Thin film optical coatings for the ultraviolet spectral region

    Science.gov (United States)

    Torchio, P.; Albrand, G.; Alvisi, M.; Amra, C.; Rauf, H.; Cousin, B.; Otrio, G.

    2017-11-01

    The applications and innovations related to the ultraviolet field are today in strong growth. To satisfy these developments which go from biomedical to the large equipment like the Storage Ring Free Electron Laser, it is crucial to control with an extreme precision the optical performances, in using the substrates and the thin film materials impossible to circumvent in this spectral range. In particular, the reduction of the losses by electromagnetic diffusion, Joule effect absorption, or the behavior under UV luminous flows of power, resistance to surrounding particulate flows... become top priority which concerns a broad European and international community. Our laboratory has the theoretical, experimental and technological tools to design and fabricate numerous multilayer coatings with desirable optical properties in the visible and infrared spectral ranges. We have extended our expertise to the ultraviolet. We present here some results on high reflectivity multidielectric mirrors towards 250 nm in wavelength, produced by Ion Plating Deposition. The latter technique allows us to obtain surface treatments with low absorption and high resistance. We give in this study the UV transparent materials and the manufacturing technology which have been the best suited to meet requirements. Single UV layers were deposited and characterized. HfO2/SiO2 mirrors with a reflectance higher than 99% at 300 nm were obtained. Optical and non-optical characterizations such as UV spectrophotometric measurements, X-Ray Diffraction spectra, Scanning Electron Microscope and Atomic Force Microscope images were performed

  15. Hungaria asteroid region telescopic spectral survey (HARTSS) I: Stony asteroids abundant in the Hungaria background population

    Science.gov (United States)

    Lucas, Michael P.; Emery, Joshua P.; Pinilla-Alonso, Noemi; Lindsay, Sean S.; Lorenzi, Vania

    2017-07-01

    The Hungaria asteroids remain as survivors of late giant planet migration that destabilized a now extinct inner portion of the primordial asteroid belt and left in its wake the current resonance structure of the Main Belt. In this scenario, the Hungaria region represents a ;purgatory; for the closest, preserved samples of the asteroidal material from which the terrestrial planets accreted. Deciphering the surface composition of these unique samples may provide constraints on the nature of the primordial building blocks of the terrestrial planets. We have undertaken an observational campaign entitled the Hungaria Asteroid Region Telescopic Spectral Survey (HARTSS) to record near-infrared (NIR) reflectance spectra in order to characterize their taxonomy, surface mineralogy, and potential meteorite analogs. The overall objective of HARTSS is to evaluate the compositional diversity of asteroids located throughout the Hungaria region. This region harbors a collisional family of Xe-type asteroids, which are situated among a background (i.e., non-family) of predominantly S-complex asteroids. In order to assess the compositional diversity of the Hungaria region, we have targeted background objects during Phase I of HARTSS. Collisional family members likely reflect the composition of one original homogeneous parent body, so we have largely avoided them in this phase. We have employed NIR instruments at two ground-based telescope facilities: the NASA Infrared Telescope Facility (IRTF), and the Telescopio Nazionale Galileo (TNG). Our data set includes the NIR spectra of 42 Hungaria asteroids (36 background; 6 family). We find that stony S-complex asteroids dominate the Hungaria background population (29/36 objects; ∼80%). C-complex asteroids are uncommon (2/42; ∼5%) within the Hungaria region. Background S-complex objects exhibit considerable spectral diversity as band parameter measurements of diagnostic absorption features near 1- and 2-μm indicate that several

  16. Methods for deconvoluting and interpreting complex gamma- and x-ray spectral regions

    International Nuclear Information System (INIS)

    Gunnink, R.

    1983-06-01

    Germanium and silicon detectors are now widely used for the detection and measurement of x and gamma radiation. However, some analysis situations and spectral regions have heretofore been too complex to deconvolute and interpret by techniques in general use. One example is the L x-ray spectrum of an element taken with a Ge or Si detector. This paper describes some new tools and methods that were developed to analyze complex spectral regions; they are illustrated with examples

  17. Upconversion based spectral imaging in 6 to 8 μm spectral regime

    DEFF Research Database (Denmark)

    Junaid, Saher; Tidemand-Lichtenberg, Peter; Pedersen, Christian

    2017-01-01

    Spectral imaging in the 6 to 8μm range has great potential for medical diagnostics. Here a novel technique based on frequency upconversion of the infrared images to the near visible for subsequent acquisition using a Si-CCD camera is investigated. The upconversion unit consists of an AgGaS2 crystal...

  18. Measurements and estimation of the columnar optical depth of tropospheric aerosols in the UV spectral region

    Directory of Open Access Journals (Sweden)

    V. E. Cachorro

    2002-04-01

    Full Text Available We report values of the columnar tropospheric aerosol optical depth at UV wavelengths based on experimental measurements of the direct spectral irradiances carried out by a commercial spectroradiometer (Li1800 of Licor company covering the range from 300–1100 nm at two stations with different climate characteristics in Spain. The first station is located in a rural site in north central Spain with continental climate. The data extend from March to the end of October of 1995. The other station is a coastal site in the Gulf of Cádiz (southwest Spain of maritime climate type. This study is mainly focused on the capability of estimating aerosol optical depth values in the UV region based on the extracted information in the visible and near infrared ranges. A first method has been used based on the Ångström turbidity parameters. However, since this method requires detailed spectral information, a second method has also been used, based on the correlation between wavelengths. A correlation has been established between the experimental aerosol optical depth values at 350 nm and 500 nm wavelengths. Although the type of aerosol seems to be the key factor that determines the quality of these estimations, the evaluation of the associated error is necessary to know the behaviour of these estimations in each area of study.Key words. Atmospheric composition and structure (aerosols and particles; transmission and scattering of radiation; troposphere – composition and chemistry

  19. Measurements and estimation of the columnar optical depth of tropospheric aerosols in the UV spectral region

    Directory of Open Access Journals (Sweden)

    V. E. Cachorro

    Full Text Available We report values of the columnar tropospheric aerosol optical depth at UV wavelengths based on experimental measurements of the direct spectral irradiances carried out by a commercial spectroradiometer (Li1800 of Licor company covering the range from 300–1100 nm at two stations with different climate characteristics in Spain. The first station is located in a rural site in north central Spain with continental climate. The data extend from March to the end of October of 1995. The other station is a coastal site in the Gulf of Cádiz (southwest Spain of maritime climate type. This study is mainly focused on the capability of estimating aerosol optical depth values in the UV region based on the extracted information in the visible and near infrared ranges. A first method has been used based on the Ångström turbidity parameters. However, since this method requires detailed spectral information, a second method has also been used, based on the correlation between wavelengths. A correlation has been established between the experimental aerosol optical depth values at 350 nm and 500 nm wavelengths. Although the type of aerosol seems to be the key factor that determines the quality of these estimations, the evaluation of the associated error is necessary to know the behaviour of these estimations in each area of study.

    Key words. Atmospheric composition and structure (aerosols and particles; transmission and scattering of radiation; troposphere – composition and chemistry

  20. [Progress in the spectral library based protein identification strategy].

    Science.gov (United States)

    Yu, Derui; Ma, Jie; Xie, Zengyan; Bai, Mingze; Zhu, Yunping; Shu, Kunxian

    2018-04-25

    Exponential growth of the mass spectrometry (MS) data is exhibited when the mass spectrometry-based proteomics has been developing rapidly. It is a great challenge to develop some quick, accurate and repeatable methods to identify peptides and proteins. Nowadays, the spectral library searching has become a mature strategy for tandem mass spectra based proteins identification in proteomics, which searches the experiment spectra against a collection of confidently identified MS/MS spectra that have been observed previously, and fully utilizes the abundance in the spectrum, peaks from non-canonical fragment ions, and other features. This review provides an overview of the implement of spectral library search strategy, and two key steps, spectral library construction and spectral library searching comprehensively, and discusses the progress and challenge of the library search strategy.

  1. Global Source Parameters from Regional Spectral Ratios for Yield Transportability Studies

    Science.gov (United States)

    Phillips, W. S.; Fisk, M. D.; Stead, R. J.; Begnaud, M. L.; Rowe, C. A.

    2016-12-01

    We use source parameters such as moment, corner frequency and high frequency rolloff as constraints in amplitude tomography, ensuring that spectra of well-studied earthquakes are recovered using the ensuing attenuation and site term model. We correct explosion data for path and site effects using such models, which allows us to test transportability of yield estimation techniques based on our best source spectral estimates. To develop a background set of source parameters, we applied spectral ratio techniques to envelopes of a global set of regional distance recordings from over 180,000 crustal events. Corner frequencies and moment ratios were determined via inversion using all event pairs within predetermined clusters, shifting to absolute levels using independently determined regional and teleseismic moments. The moment and corner frequency results can be expressed as stress drop, which has considerable scatter, yet shows dramatic regional patterns. We observe high stress in subduction zones along S. America, S. Mexico, the Banda Sea, and associated with the Yakutat Block in Alaska. We also observe high stress at the Himalayan syntaxes, the Pamirs, eastern Iran, the Caspian, the Altai-Sayan, and the central African rift. Low stress is observed along mid ocean spreading centers, the Afar rift, patches of convergence zones such as Nicaragua, the Zagros, Tibet, and the Tien Shan, among others. Mine blasts appear as low stress events due to their low corners and steep rolloffs. Many of these anomalies have been noted by previous studies, and we plan to compare results directly. As mentioned, these results will be used to constrain tomographic imaging, but can also be used in model validation procedures similar to the use of ground truth in location problems, and, perhaps most importantly, figure heavily in quality control of local and regional distance amplitude measurements.

  2. [Research on Spectral Polarization Imaging System Based on Static Modulation].

    Science.gov (United States)

    Zhao, Hai-bo; Li, Huan; Lin, Xu-ling; Wang, Zheng

    2015-04-01

    The main disadvantages of traditional spectral polarization imaging system are: complex structure, with moving parts, low throughput. A novel method of spectral polarization imaging system is discussed, which is based on static polarization intensity modulation combined with Savart polariscope interference imaging. The imaging system can obtain real-time information of spectral and four Stokes polarization messages. Compared with the conventional methods, the advantages of the imaging system are compactness, low mass and no moving parts, no electrical control, no slit and big throughput. The system structure and the basic theory are introduced. The experimental system is established in the laboratory. The experimental system consists of reimaging optics, polarization intensity module, interference imaging module, and CCD data collecting and processing module. The spectral range is visible and near-infrared (480-950 nm). The white board and the plane toy are imaged by using the experimental system. The ability of obtaining spectral polarization imaging information is verified. The calibration system of static polarization modulation is set up. The statistical error of polarization degree detection is less than 5%. The validity and feasibility of the basic principle is proved by the experimental result. The spectral polarization data captured by the system can be applied to object identification, object classification and remote sensing detection.

  3. Global Infrared–Radio Spectral Energy Distributions of Galactic Massive Star-Forming Regions

    Science.gov (United States)

    Povich, Matthew Samuel; Binder, Breanna Arlene

    2018-01-01

    We present a multiwavelength study of 30 Galactic massive star-forming regions. We fit multicomponent dust, blackbody, and power-law continuum models to 3.6 µm through 10 mm spectral energy distributions obtained from Spitzer, MSX, IRAS, Herschel, and Planck archival survey data. Averaged across our sample, ~20% of Lyman continuum photons emitted by massive stars are absorbed by dust before contributing to the ionization of H II regions, while ~50% of the stellar bolometric luminosity is absorbed and reprocessed by dust in the H II regions and surrounding photodissociation regions. The most luminous, infrared-bright regions that fully sample the upper stellar initial mass function (ionizing photon rates NC ≥ 1050 s–1 and total infrared luminosity LTIR ≥ 106.8 L⊙) have higher percentages of absorbed Lyman continuum photons (~40%) and dust-reprocessed starlight (~80%). The monochromatic 70-µm luminosity L70 is linearly correlated with LTIR, and on average L70/LTIR = 50%, in good agreement with extragalactic studies. Calibrated against the known massive stellar content in our sampled H II regions, we find that star formation rates based on L70 are in reasonably good agreement with extragalactic calibrations, when corrected for the smaller physical sizes of the Galactic regions. We caution that absorption of Lyman continuum photons prior to contributing to the observed ionizing photon rate may reduce the attenuation-corrected Hα emission, systematically biasing extragalactic calibrations toward lower star formation rates when applied to spatially-resolved studies of obscured star formation.This work was supported by the National Science Foundation under award CAREER-1454333.

  4. The influence of spectral nudging on typhoon formation in regional climate models

    Science.gov (United States)

    Feser, Frauke; Barcikowska, Monika

    2012-03-01

    Regional climate models can successfully simulate tropical cyclones and typhoons. This has been shown and was evaluated for hindcast studies of the past few decades. But often global and regional weather phenomena are not simulated at the observed location, or occur too often or seldom even though the regional model is driven by global reanalysis data which constitute a near-realistic state of the global atmosphere. Therefore, several techniques have been developed in order to make the regional model follow the global state more closely. One is spectral nudging, which is applied for horizontal wind components with increasing strength for higher model levels in this study. The aim of this study is to show the influence that this method has on the formation of tropical cyclones (TC) in regional climate models. Two ensemble simulations (each with five simulations) were computed for Southeast Asia and the Northwestern Pacific for the typhoon season 2004, one with spectral nudging and one without. First of all, spectral nudging reduced the overall TC number by about a factor of 2. But the number of tracks which are similar to observed best track data (BTD) was greatly increased. Also, spatial track density patterns were found to be more similar when using spectral nudging. The tracks merge after a short time for the spectral nudging simulations and then follow the BTD closely; for the no nudge cases the similarity is greatly reduced. A comparison of seasonal precipitation, geopotential height, and temperature fields at several height levels with observations and reanalysis data showed overall a smaller ensemble spread, higher pattern correlations and reduced root mean square errors and biases for the spectral nudged simulations. Vertical temperature profiles for selected TCs indicate that spectral nudging is not inhibiting TC development at higher levels. Both the Madden-Julian Oscillation and monsoonal precipitation are reproduced realistically by the regional model

  5. The influence of spectral nudging on typhoon formation in regional climate models

    International Nuclear Information System (INIS)

    Feser, Frauke; Barcikowska, Monika

    2012-01-01

    Regional climate models can successfully simulate tropical cyclones and typhoons. This has been shown and was evaluated for hindcast studies of the past few decades. But often global and regional weather phenomena are not simulated at the observed location, or occur too often or seldom even though the regional model is driven by global reanalysis data which constitute a near-realistic state of the global atmosphere. Therefore, several techniques have been developed in order to make the regional model follow the global state more closely. One is spectral nudging, which is applied for horizontal wind components with increasing strength for higher model levels in this study. The aim of this study is to show the influence that this method has on the formation of tropical cyclones (TC) in regional climate models. Two ensemble simulations (each with five simulations) were computed for Southeast Asia and the Northwestern Pacific for the typhoon season 2004, one with spectral nudging and one without. First of all, spectral nudging reduced the overall TC number by about a factor of 2. But the number of tracks which are similar to observed best track data (BTD) was greatly increased. Also, spatial track density patterns were found to be more similar when using spectral nudging. The tracks merge after a short time for the spectral nudging simulations and then follow the BTD closely; for the no nudge cases the similarity is greatly reduced. A comparison of seasonal precipitation, geopotential height, and temperature fields at several height levels with observations and reanalysis data showed overall a smaller ensemble spread, higher pattern correlations and reduced root mean square errors and biases for the spectral nudged simulations. Vertical temperature profiles for selected TCs indicate that spectral nudging is not inhibiting TC development at higher levels. Both the Madden–Julian Oscillation and monsoonal precipitation are reproduced realistically by the regional model

  6. Dielectric properties of semi-insulating Fe-doped InP in the terahertz spectral region.

    Science.gov (United States)

    Alyabyeva, L N; Zhukova, E S; Belkin, M A; Gorshunov, B P

    2017-08-04

    We report the values and the spectral dependence of the real and imaginary parts of the dielectric permittivity of semi-insulating Fe-doped InP crystalline wafers in the 2-700 cm -1 (0.06-21 THz) spectral region at room temperature. The data shows a number of absorption bands that are assigned to one- and two-phonon and impurity-related absorption processes. Unlike the previous studies of undoped or low-doped InP material, our data unveil the dielectric properties of InP that are not screened by strong free-carrier absorption and will be useful for designing a wide variety of InP-based electronic and photonic devices operating in the terahertz spectral range.

  7. Hyperspectral image classifier based on beach spectral feature

    International Nuclear Information System (INIS)

    Liang, Zhang; Lianru, Gao; Bing, Zhang

    2014-01-01

    The seashore, especially coral bank, is sensitive to human activities and environmental changes. A multispectral image, with coarse spectral resolution, is inadaptable for identify subtle spectral distinctions between various beaches. To the contrary, hyperspectral image with narrow and consecutive channels increases our capability to retrieve minor spectral features which is suit for identification and classification of surface materials on the shore. Herein, this paper used airborne hyperspectral data, in addition to ground spectral data to study the beaches in Qingdao. The image data first went through image pretreatment to deal with the disturbance of noise, radiation inconsistence and distortion. In succession, the reflection spectrum, the derivative spectrum and the spectral absorption features of the beach surface were inspected in search of diagnostic features. Hence, spectra indices specific for the unique environment of seashore were developed. According to expert decisions based on image spectrums, the beaches are ultimately classified into sand beach, rock beach, vegetation beach, mud beach, bare land and water. In situ surveying reflection spectrum from GER1500 field spectrometer validated the classification production. In conclusion, the classification approach under expert decision based on feature spectrum is proved to be feasible for beaches

  8. Regularized image denoising based on spectral gradient optimization

    International Nuclear Information System (INIS)

    Lukić, Tibor; Lindblad, Joakim; Sladoje, Nataša

    2011-01-01

    Image restoration methods, such as denoising, deblurring, inpainting, etc, are often based on the minimization of an appropriately defined energy function. We consider energy functions for image denoising which combine a quadratic data-fidelity term and a regularization term, where the properties of the latter are determined by a used potential function. Many potential functions are suggested for different purposes in the literature. We compare the denoising performance achieved by ten different potential functions. Several methods for efficient minimization of regularized energy functions exist. Most are only applicable to particular choices of potential functions, however. To enable a comparison of all the observed potential functions, we propose to minimize the objective function using a spectral gradient approach; spectral gradient methods put very weak restrictions on the used potential function. We present and evaluate the performance of one spectral conjugate gradient and one cyclic spectral gradient algorithm, and conclude from experiments that both are well suited for the task. We compare the performance with three total variation-based state-of-the-art methods for image denoising. From the empirical evaluation, we conclude that denoising using the Huber potential (for images degraded by higher levels of noise; signal-to-noise ratio below 10 dB) and the Geman and McClure potential (for less noisy images), in combination with the spectral conjugate gradient minimization algorithm, shows the overall best performance

  9. Accurate and independent spectral response scale based on silicon trap detectors and spectrally invariant detectors

    International Nuclear Information System (INIS)

    Gran, Jarle

    2005-01-01

    The study aims to establish an independent high accuracy spectral response scale over a broad spectral range based on standard laboratory equipment at a moderate cost. This had to be done by a primary method, where the responsivity of the detector is linked to fundamental constants. Summary, conclusion and future directions: In this thesis it has been demonstrated that an independent spectral response scale from the visual to the IR based on simple relative measurements can be established. The accuracy obtained by the hybrid self-calibration method demonstrates that state of the art accuracy is obtained with self-calibration principles. A calculable silicon trap detector with low internal losses over a wide spectral range is needed to establish the scale, in addition to a linear, spectrally independent detector with a good signal to noise ratio. By fitting the parameters in the responsivity model to a purely relative measurement we express the spectral response in terms of fundamental constants with a known uncertainty This is therefore a primary method. By applying a digital filter on the relative measurements of the InGaAs detectors in the infrared reduces the standard deviation by 30 %. In addition, by optimising the necessary scaling constant converting the relative calibration to absolute values, we have managed to establish an accurate and cost efficient spectral response scale in the IR. The full covariance analysis, which takes into account the correlation in the absolute values of the silicon detector, the correlation caused by the filter and the scaling constant, shows that the spectral response scale established in the infrared with InGaAs detectors is done with high accuracy. A similar procedure can be used in the UV, though it has not been demonstrated here. In fig. 10 the responsitivities of the detectors (a) and their associated uncertainties (b) at the 1 sigma level of confidence is compared for the three publications. We see that the responsivity

  10. Impact of spectral nudging on regional climate simulation over CORDEX East Asia using WRF

    Science.gov (United States)

    Tang, Jianping; Wang, Shuyu; Niu, Xiaorui; Hui, Pinhong; Zong, Peishu; Wang, Xueyuan

    2017-04-01

    In this study, the impact of the spectral nudging method on regional climate simulation over the Coordinated Regional Climate Downscaling Experiment East Asia (CORDEX-EA) region is investigated using the Weather Research and Forecasting model (WRF). Driven by the ERA-Interim reanalysis, five continuous simulations covering 1989-2007 are conducted by the WRF model, in which four runs adopt the interior spectral nudging with different wavenumbers, nudging variables and nudging coefficients. Model validation shows that WRF has the ability to simulate spatial distributions and temporal variations of the surface climate (air temperature and precipitation) over CORDEX-EA domain. Comparably the spectral nudging technique is effective in improving the model's skill in the following aspects: (1), the simulated biases and root mean square errors of annual mean temperature and precipitation are obviously reduced. The SN3-UVT (spectral nudging with wavenumber 3 in both zonal and meridional directions applied to U, V and T) and SN6 (spectral nudging with wavenumber 6 in both zonal and meridional directions applied to U and V) experiments give the best simulations for temperature and precipitation respectively. The inter-annual and seasonal variances produced by the SN experiments are also closer to the ERA-Interim observation. (2), the application of spectral nudging in WRF is helpful for simulating the extreme temperature and precipitation, and the SN3-UVT simulation shows a clear advantage over the other simulations in depicting both the spatial distributions and inter-annual variances of temperature and precipitation extremes. With the spectral nudging, WRF is able to preserve the variability in the large scale climate information, and therefore adjust the temperature and precipitation variabilities toward the observation.

  11. Multi scales based sparse matrix spectral clustering image segmentation

    Science.gov (United States)

    Liu, Zhongmin; Chen, Zhicai; Li, Zhanming; Hu, Wenjin

    2018-04-01

    In image segmentation, spectral clustering algorithms have to adopt the appropriate scaling parameter to calculate the similarity matrix between the pixels, which may have a great impact on the clustering result. Moreover, when the number of data instance is large, computational complexity and memory use of the algorithm will greatly increase. To solve these two problems, we proposed a new spectral clustering image segmentation algorithm based on multi scales and sparse matrix. We devised a new feature extraction method at first, then extracted the features of image on different scales, at last, using the feature information to construct sparse similarity matrix which can improve the operation efficiency. Compared with traditional spectral clustering algorithm, image segmentation experimental results show our algorithm have better degree of accuracy and robustness.

  12. Tensor-Based Dictionary Learning for Spectral CT Reconstruction.

    Science.gov (United States)

    Zhang, Yanbo; Mou, Xuanqin; Wang, Ge; Yu, Hengyong

    2017-01-01

    Spectral computed tomography (CT) produces an energy-discriminative attenuation map of an object, extending a conventional image volume with a spectral dimension. In spectral CT, an image can be sparsely represented in each of multiple energy channels, and are highly correlated among energy channels. According to this characteristics, we propose a tensor-based dictionary learning method for spectral CT reconstruction. In our method, tensor patches are extracted from an image tensor, which is reconstructed using the filtered backprojection (FBP), to form a training dataset. With the Candecomp/Parafac decomposition, a tensor-based dictionary is trained, in which each atom is a rank-one tensor. Then, the trained dictionary is used to sparsely represent image tensor patches during an iterative reconstruction process, and the alternating minimization scheme is adapted for optimization. The effectiveness of our proposed method is validated with both numerically simulated and real preclinical mouse datasets. The results demonstrate that the proposed tensor-based method generally produces superior image quality, and leads to more accurate material decomposition than the currently popular popular methods.

  13. Tensor-based Dictionary Learning for Spectral CT Reconstruction

    Science.gov (United States)

    Zhang, Yanbo; Wang, Ge

    2016-01-01

    Spectral computed tomography (CT) produces an energy-discriminative attenuation map of an object, extending a conventional image volume with a spectral dimension. In spectral CT, an image can be sparsely represented in each of multiple energy channels, and are highly correlated among energy channels. According to this characteristics, we propose a tensor-based dictionary learning method for spectral CT reconstruction. In our method, tensor patches are extracted from an image tensor, which is reconstructed using the filtered backprojection (FBP), to form a training dataset. With the Candecomp/Parafac decomposition, a tensor-based dictionary is trained, in which each atom is a rank-one tensor. Then, the trained dictionary is used to sparsely represent image tensor patches during an iterative reconstruction process, and the alternating minimization scheme is adapted for optimization. The effectiveness of our proposed method is validated with both numerically simulated and real preclinical mouse datasets. The results demonstrate that the proposed tensor-based method generally produces superior image quality, and leads to more accurate material decomposition than the currently popular popular methods. PMID:27541628

  14. A wavelet and least square filter based spatial-spectral denoising approach of hyperspectral imagery

    Science.gov (United States)

    Li, Ting; Chen, Xiao-Mei; Chen, Gang; Xue, Bo; Ni, Guo-Qiang

    2009-11-01

    Noise reduction is a crucial step in hyperspectral imagery pre-processing. Based on sensor characteristics, the noise of hyperspectral imagery represents in both spatial and spectral domain. However, most prevailing denosing techniques process the imagery in only one specific domain, which have not utilized multi-domain nature of hyperspectral imagery. In this paper, a new spatial-spectral noise reduction algorithm is proposed, which is based on wavelet analysis and least squares filtering techniques. First, in the spatial domain, a new stationary wavelet shrinking algorithm with improved threshold function is utilized to adjust the noise level band-by-band. This new algorithm uses BayesShrink for threshold estimation, and amends the traditional soft-threshold function by adding shape tuning parameters. Comparing with soft or hard threshold function, the improved one, which is first-order derivable and has a smooth transitional region between noise and signal, could save more details of image edge and weaken Pseudo-Gibbs. Then, in the spectral domain, cubic Savitzky-Golay filter based on least squares method is used to remove spectral noise and artificial noise that may have been introduced in during the spatial denoising. Appropriately selecting the filter window width according to prior knowledge, this algorithm has effective performance in smoothing the spectral curve. The performance of the new algorithm is experimented on a set of Hyperion imageries acquired in 2007. The result shows that the new spatial-spectral denoising algorithm provides more significant signal-to-noise-ratio improvement than traditional spatial or spectral method, while saves the local spectral absorption features better.

  15. Deficits of magnetoencephalography regional power in patients with major depressive disorder:an individual spectral analysis

    Institute of Scientific and Technical Information of China (English)

    汤浩

    2014-01-01

    Objective To explore the discrepancies of individualized frequency and band power between major depressive disorder(MDD)and controls in resting state,and the association of abnormal spectral power with clinical severity of MDD.Methods Whole-head MEG recordings were collected in 19 patients with MDD and 19 non-depressed controls in eye-closed resting state.Individual spectral power of each subject was calculated based on

  16. Regional Spectral Model Workshop in memory of John Roads and Masao Kanamitsu

    Science.gov (United States)

    Hann-Ming Henry Juang; Shyh-Chin Chen; Songyou Hong; Hideki Kanamaru; Thomas Reichler; Takeshi Enomoto; Dian Putrasahan; Bruce T. Anderson; Sasha Gershunov; Haiqin Li; Kei Yoshimura; Nikolaus Buenning; Diane Boomer

    2014-01-01

    The committee for the 12th International Regional Spectral Model (RSM) Workshop drew its members from the National Centers for Environmental Prediction (NCEP), the U.S. Forest Service, Yonsei University, the Cooperative Institute for Climate and Satellites, the University of Tokyo, the Food and Agriculture Organization of the United Nations (FAO), Hokkaido University,...

  17. SPECTRAL RECONSTRUCTION BASED ON SVM FOR CROSS CALIBRATION

    Directory of Open Access Journals (Sweden)

    H. Gao

    2017-05-01

    Full Text Available Chinese HY-1C/1D satellites will use a 5nm/10nm-resolutional visible-near infrared(VNIR hyperspectral sensor with the solar calibrator to cross-calibrate with other sensors. The hyperspectral radiance data are composed of average radiance in the sensor’s passbands and bear a spectral smoothing effect, a transform from the hyperspectral radiance data to the 1-nm-resolution apparent spectral radiance by spectral reconstruction need to be implemented. In order to solve the problem of noise cumulation and deterioration after several times of iteration by the iterative algorithm, a novel regression method based on SVM is proposed, which can approach arbitrary complex non-linear relationship closely and provide with better generalization capability by learning. In the opinion of system, the relationship between the apparent radiance and equivalent radiance is nonlinear mapping introduced by spectral response function(SRF, SVM transform the low-dimensional non-linear question into high-dimensional linear question though kernel function, obtaining global optimal solution by virtue of quadratic form. The experiment is performed using 6S-simulated spectrums considering the SRF and SNR of the hyperspectral sensor, measured reflectance spectrums of water body and different atmosphere conditions. The contrastive result shows: firstly, the proposed method is with more reconstructed accuracy especially to the high-frequency signal; secondly, while the spectral resolution of the hyperspectral sensor reduces, the proposed method performs better than the iterative method; finally, the root mean square relative error(RMSRE which is used to evaluate the difference of the reconstructed spectrum and the real spectrum over the whole spectral range is calculated, it decreses by one time at least by proposed method.

  18. Spectral radiative property control method based on filling solution

    International Nuclear Information System (INIS)

    Jiao, Y.; Liu, L.H.; Hsu, P.-F.

    2014-01-01

    Controlling thermal radiation by tailoring spectral properties of microstructure is a promising method, can be applied in many industrial systems and have been widely researched recently. Among various property tailoring schemes, geometry design of microstructures is a commonly used method. However, the existing radiation property tailoring is limited by adjustability of processed microstructures. In other words, the spectral radiative properties of microscale structures are not possible to change after the gratings are fabricated. In this paper, we propose a method that adjusts the grating spectral properties by means of injecting filling solution, which could modify the thermal radiation in a fabricated microstructure. Therefore, this method overcomes the limitation mentioned above. Both mercury and water are adopted as the filling solution in this study. Aluminum and silver are selected as the grating materials to investigate the generality and limitation of this control method. The rigorous coupled-wave analysis is used to investigate the spectral radiative properties of these filling solution grating structures. A magnetic polaritons mechanism identification method is proposed based on LC circuit model principle. It is found that this control method could be used by different grating materials. Different filling solutions would enable the high absorption peak to move to longer or shorter wavelength band. The results show that the filling solution grating structures are promising for active control of spectral radiative properties. -- Highlights: • A filling solution grating structure is designed to adjust spectral radiative properties. • The mechanism of radiative property control is studied for engineering utilization. • Different grating materials are studied to find multi-functions for grating

  19. Topographic gradient based site characterization in India complemented by strong ground-motion spectral attributes

    KAUST Repository

    Nath, Sankar Kumar; Thingbaijam, Kiran Kumar; Adhikari, M. D.; Nayak, Avinash; Devaraj, N.; Ghosh, Soumalya K.; Mahajan, Arun K.

    2013-01-01

    We appraise topographic-gradient approach for site classification that employs correlations between 30. m column averaged shear-wave velocity and topographic gradients. Assessments based on site classifications reported from cities across India indicate that the approach is reasonably viable at regional level. Additionally, we experiment three techniques for site classification based on strong ground-motion recordings, namely Horizontal-to-Vertical Spectral Ratio (HVSR), Response Spectra Shape (RSS), and Horizontal-to-Vertical Response Spectral Ratio (HVRSR) at the strong motion stations located across the Himalayas and northeast India. Statistical tests on the results indicate that these three techniques broadly differentiate soil and rock sites while RSS and HVRSR yield better signatures. The results also support the implemented site classification in the light of strong ground-motion spectral attributes observed in different parts of the globe. © 2013 Elsevier Ltd.

  20. Topographic gradient based site characterization in India complemented by strong ground-motion spectral attributes

    KAUST Repository

    Nath, Sankar Kumar

    2013-12-01

    We appraise topographic-gradient approach for site classification that employs correlations between 30. m column averaged shear-wave velocity and topographic gradients. Assessments based on site classifications reported from cities across India indicate that the approach is reasonably viable at regional level. Additionally, we experiment three techniques for site classification based on strong ground-motion recordings, namely Horizontal-to-Vertical Spectral Ratio (HVSR), Response Spectra Shape (RSS), and Horizontal-to-Vertical Response Spectral Ratio (HVRSR) at the strong motion stations located across the Himalayas and northeast India. Statistical tests on the results indicate that these three techniques broadly differentiate soil and rock sites while RSS and HVRSR yield better signatures. The results also support the implemented site classification in the light of strong ground-motion spectral attributes observed in different parts of the globe. © 2013 Elsevier Ltd.

  1. Mapping accuracy via spectrally and structurally based filtering techniques: comparisons through visual observations

    Science.gov (United States)

    Chockalingam, Letchumanan

    2005-01-01

    The data of Gunung Ledang region of Malaysia acquired through LANDSAT are considered to map certain hydrogeolocial features. To map these significant features, image-processing tools such as contrast enhancement, edge detection techniques are employed. The advantages of these techniques over the other methods are evaluated from the point of their validity in properly isolating features of hydrogeolocial interest are discussed. As these techniques take the advantage of spectral aspects of the images, these techniques have several limitations to meet the objectives. To discuss these limitations, a morphological transformation, which generally considers the structural aspects rather than spectral aspects from the image, are applied to provide comparisons between the results derived from spectral based and the structural based filtering techniques.

  2. High-Speed Target Identification System Based on the Plume’s Spectral Distribution

    Directory of Open Access Journals (Sweden)

    Wenjie Lang

    2015-01-01

    Full Text Available In order to recognize the target of high speed quickly and accurately, an identification system was designed based on analysis of the distribution characteristics of the plume spectrum. In the system, the target was aligned with visible light tracking module, and the spectral analysis of the target’s plume radiation was achieved by interference module. The distinguishing factor recognition algorithm was designed on basis of ratio of multifeature band peaks and valley mean values. Effective recognition of the high speed moving target could be achieved after partition of the active region and the influence of target motion on spectral acquisition was analyzed. In the experiment the small rocket combustion was used as the target. The spectral detection experiment was conducted at different speeds 2.0 km away from the detection system. Experimental results showed that spectral distribution had significant spectral offset in the same sampling period for the target with different speeds, but the spectral distribution was basically consistent. Through calculation of the inclusion relationship between distinguishing factor and distinction interval of the peak value and the valley value at the corresponding wave-bands, effective identification of target could be achieved.

  3. Prediction of spectral acceleration response ordinates based on PGA attenuation

    Science.gov (United States)

    Graizer, V.; Kalkan, E.

    2009-01-01

    Developed herein is a new peak ground acceleration (PGA)-based predictive model for 5% damped pseudospectral acceleration (SA) ordinates of free-field horizontal component of ground motion from shallow-crustal earthquakes. The predictive model of ground motion spectral shape (i.e., normalized spectrum) is generated as a continuous function of few parameters. The proposed model eliminates the classical exhausted matrix of estimator coefficients, and provides significant ease in its implementation. It is structured on the Next Generation Attenuation (NGA) database with a number of additions from recent Californian events including 2003 San Simeon and 2004 Parkfield earthquakes. A unique feature of the model is its new functional form explicitly integrating PGA as a scaling factor. The spectral shape model is parameterized within an approximation function using moment magnitude, closest distance to the fault (fault distance) and VS30 (average shear-wave velocity in the upper 30 m) as independent variables. Mean values of its estimator coefficients were computed by fitting an approximation function to spectral shape of each record using robust nonlinear optimization. Proposed spectral shape model is independent of the PGA attenuation, allowing utilization of various PGA attenuation relations to estimate the response spectrum of earthquake recordings.

  4. Spectral CT metal artifact reduction with an optimization-based reconstruction algorithm

    Science.gov (United States)

    Gilat Schmidt, Taly; Barber, Rina F.; Sidky, Emil Y.

    2017-03-01

    Metal objects cause artifacts in computed tomography (CT) images. This work investigated the feasibility of a spectral CT method to reduce metal artifacts. Spectral CT acquisition combined with optimization-based reconstruction is proposed to reduce artifacts by modeling the physical effects that cause metal artifacts and by providing the flexibility to selectively remove corrupted spectral measurements in the spectral-sinogram space. The proposed Constrained `One-Step' Spectral CT Image Reconstruction (cOSSCIR) algorithm directly estimates the basis material maps while enforcing convex constraints. The incorporation of constraints on the reconstructed basis material maps is expected to mitigate undersampling effects that occur when corrupted data is excluded from reconstruction. The feasibility of the cOSSCIR algorithm to reduce metal artifacts was investigated through simulations of a pelvis phantom. The cOSSCIR algorithm was investigated with and without the use of a third basis material representing metal. The effects of excluding data corrupted by metal were also investigated. The results demonstrated that the proposed cOSSCIR algorithm reduced metal artifacts and improved CT number accuracy. For example, CT number error in a bright shading artifact region was reduced from 403 HU in the reference filtered backprojection reconstruction to 33 HU using the proposed algorithm in simulation. In the dark shading regions, the error was reduced from 1141 HU to 25 HU. Of the investigated approaches, decomposing the data into three basis material maps and excluding the corrupted data demonstrated the greatest reduction in metal artifacts.

  5. Magnetorefractive effect in manganites with a colossal magnetoresistance in the visible spectral region

    Energy Technology Data Exchange (ETDEWEB)

    Sukhorukov, Yu. P., E-mail: suhorukov@imp.uran.ru; Telegin, A. V. [Russian Academy of Sciences, Institute of Metal Physics, Ural Branch (Russian Federation); Granovsky, A. B., E-mail: granov@magn.ru; Gan' shina, E. A. [Moscow State University, Faculty of Physics (Russian Federation); Zhukov, A.; Gonzalez, J. [Universidad del Pais Vasco (UPV)/Euskal Herriko Unibertsitatea (EHU), Departamento de Fisica de Materiales, Facultad de Quimica (Spain); Herranz, G. [Institut de Ciencia de Materials de Barcelona (ICMAB)-CSIC (Spain); Caicedo, J. M. [Universidad del Pais Vasco (UPV)/Euskal Herriko Unibertsitatea (EHU), Departamento de Fisica de Materiales, Facultad de Quimica (Spain); Yurasov, A. N. [Moscow State Institute of Radio-Engineering, Electronics, and Automation (Technical University) (Russian Federation); Bessonov, V. D. [Russian Academy of Sciences, Institute of Metal Physics, Ural Branch (Russian Federation); Kaul' , A. R.; Gorbenko, O. Yu.; Korsakov, I. E. [Moscow State University, Faculty of Physics (Russian Federation)

    2012-01-15

    The magnetotransmission, magnetoreflection, and magnetoresistance of the La{sub 0.7}Ca{sub 0.3}MnO{sub 3} and La{sub 0.9}Ag{sub 0.1}MnO{sub 3} epitaxial films have been investigated. It has been found that the films exhibit a significant magnetorefractive effect in the case of reflection and transmission of light in the fundamental absorption region both in the vicinity of the Curie temperature and at low temperatures. It has been shown that the magnetorefractive effect in the infrared spectral region of the manganites is determined by a high-frequency response to magnetoresistance, whereas the magnetorefractive effect in the visible spectral region of these materials is associated with a change in the electronic structure in response to a magnetic field, which, in turn, leads to a change in the electron density of states, the probability of interband optical transitions, and the shift of light absorption bands. The obtained values of the magnetotransmittance and magnetoreflectance in the visible spectral region are less than those observed in the infrared region of the spectrum, but they are several times greater than the linear magneto-optical effects. As a result, the magnetorefractive effect, which is a nongyrotropic phenomenon, makes it possible to avoid the use of light analyzers and polarizers in optical circuits.

  6. Magnetorefractive effect in manganites with a colossal magnetoresistance in the visible spectral region

    International Nuclear Information System (INIS)

    Sukhorukov, Yu. P.; Telegin, A. V.; Granovsky, A. B.; Gan’shina, E. A.; Zhukov, A.; Gonzalez, J.; Herranz, G.; Caicedo, J. M.; Yurasov, A. N.; Bessonov, V. D.; Kaul’, A. R.; Gorbenko, O. Yu.; Korsakov, I. E.

    2012-01-01

    The magnetotransmission, magnetoreflection, and magnetoresistance of the La 0.7 Ca 0.3 MnO 3 and La 0.9 Ag 0.1 MnO 3 epitaxial films have been investigated. It has been found that the films exhibit a significant magnetorefractive effect in the case of reflection and transmission of light in the fundamental absorption region both in the vicinity of the Curie temperature and at low temperatures. It has been shown that the magnetorefractive effect in the infrared spectral region of the manganites is determined by a high-frequency response to magnetoresistance, whereas the magnetorefractive effect in the visible spectral region of these materials is associated with a change in the electronic structure in response to a magnetic field, which, in turn, leads to a change in the electron density of states, the probability of interband optical transitions, and the shift of light absorption bands. The obtained values of the magnetotransmittance and magnetoreflectance in the visible spectral region are less than those observed in the infrared region of the spectrum, but they are several times greater than the linear magneto-optical effects. As a result, the magnetorefractive effect, which is a nongyrotropic phenomenon, makes it possible to avoid the use of light analyzers and polarizers in optical circuits.

  7. Tissues segmentation based on multi spectral medical images

    Science.gov (United States)

    Li, Ya; Wang, Ying

    2017-11-01

    Each band image contains the most obvious tissue feature according to the optical characteristics of different tissues in different specific bands for multispectral medical images. In this paper, the tissues were segmented by their spectral information at each multispectral medical images. Four Local Binary Patter descriptors were constructed to extract blood vessels based on the gray difference between the blood vessels and their neighbors. The segmented tissue in each band image was merged to a clear image.

  8. Spectral responsivity-based calibration of photometer and colorimeter standards

    Science.gov (United States)

    Eppeldauer, George P.

    2013-08-01

    Several new generation transfer- and working-standard illuminance meters and tristimulus colorimeters have been developed at the National Institute of Standards and Technology (NIST) [1] to measure all kinds of light sources with low uncertainty. The spectral and broad-band (illuminance) responsivities of the photometer (Y) channels of two tristimulus meters were determined at both the Spectral Irradiance and Radiance Responsivity Calibrations using Uniform Sources (SIRCUS) facility and the Spectral Comparator Facility (SCF) [2]. The two illuminance responsivities agreed within 0.1% with an overall uncertainty of 0.2% (k = 2), which is a factor of two improvement over the present NIST photometric scale. The first detector-based tristimulus color scale [3] was realized. All channels of the reference tristimulus colorimeter were calibrated at the SIRCUS. The other tristimulus meters were calibrated at the SCF and also against the reference meter on the photometry bench in broad-band measurement mode. The agreement between detector- and source-based calibrations was within 3 K when a tungsten lamp-standard was measured at 2856 K and 3100 K [4]. The color-temperature uncertainty of tungsten lamp measurements was 4 K (k = 2) between 2300 K and 3200 K, which is a factor of two improvement over the presently used NIST source-based color temperature scale. One colorimeter was extended with an additional (fifth) channel to apply software implemented matrix corrections. With this correction, the spectral mismatch caused color difference errors were decreased by a factor of 20 for single-color LEDs.

  9. Identification of toxic cyclopeptides based on mass spectral library matching

    Directory of Open Access Journals (Sweden)

    Boris L. Milman

    2014-08-01

    Full Text Available To gain perspective on the use of tandem mass spectral libraries for identification of toxic cyclic peptides, the new library was built from 263 mass spectra (mainly MS2 spectra of 59 compounds of that group, such as microcystins, amatoxins, and some related compounds. Mass spectra were extracted from the literature or specially acquired on ESI-Q-ToF and MALDI-ToF/ToF tandem instruments. ESI-MS2 product-ion mass spectra appeared to be rather close to MALDI-ToF/ToF fragment spectra which are uncommon for mass spectral libraries. Testing of the library was based on searches where reference spectra were in turn cross-compared. The percentage of 1st rank correct identifications (true positives was 70% in a general case and 88–91% without including knowingly defective (‘one-dimension’ spectra as test ones. The percentage of 88–91% is the principal estimate for the overall performance of this library that can be used in a method of choice for identification of individual cyclopeptides and also for group recognition of individual classes of such peptides. The approach to identification of cyclopeptides based on mass spectral library matching proved to be the most effective for abundant toxins. That was confirmed by analysis of extracts from two cyanobacterial strains.

  10. Titanium-based spectrally selective surfaces for solar thermal systems

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, A D; Holmes, J P

    1983-10-01

    A study of spectrally selective surfaces based on anodic oxide films on titanium is presented. These surfaces have low values of solar absorptance, 0.77, due to the nonideal optical properties of the anodic TiO2 for antireflection of titanium. A simple chemical etching process is described which gives a textured surface with dimensions similar to the wavelengths of solar radiation, leading to spectral selectivity. The performance of this dark-etched surface can be further improved by anodising, and optimum absorbers have been produced with alpha(s) 0.935 and hemispherical emittances (400 K) 0.23. The surface texturing effects a significant improvement in alpha(s) at oblique incidence.

  11. Identification of the optimal spectral region for plasmonic and nanoplasmonic sensing.

    Science.gov (United States)

    Otte, Marinus A; Sepúlveda, Borja; Ni, Weihai; Juste, Jorge Pérez; Liz-Marzán, Luis M; Lechuga, Laura M

    2010-01-26

    We present a theoretical and experimental study involving the sensing characteristics of wavelength-interrogated plasmonic sensors based on surface plasmon polaritons (SPP) in planar gold films and on localized surface plasmon resonances (LSPR) of single gold nanorods. The tunability of both sensing platforms allowed us to analyze their bulk and surface sensing characteristics as a function of the plasmon resonance position. We demonstrate that a general figure of merit (FOM), which is equivalent in wavelength and energy scales, can be employed to mutually compare both sensing schemes. Most interestingly, this FOM has revealed a spectral region for which the surface sensitivity performance of both sensor types is optimized, which we attribute to the intrinsic dielectric properties of plasmonic materials. Additionally, in good agreement with theoretical predictions, we experimentally demonstrate that, although the SPP sensor offers a much better bulk sensitivity, the LSPR sensor shows an approximately 15% better performance for surface sensitivity measurements when its FOM is optimized. However, optimization of the substrate refractive index and the accessibility of the relevant molecules to the nanoparticles can lead to a total 3-fold improvement of the FOM in LSPR sensors.

  12. Spectral nudging in regional climate modelling: How strongly should we nudge?

    OpenAIRE

    Omrani , Hiba; Drobinski , Philippe; Dubos , Thomas

    2012-01-01

    International audience; Spectral nudging is a technique consisting in driving regional climate models (RCMs) on selected spatial scales corresponding to those produced by the driving global circulation model (GCM). This technique prevents large and unrealistic departures between the GCM driving fields and the RCM fields at the GCM spatial scales. Theoretically, the relaxation of the RCM towards the GCM should be infinitely strong provided thre are perfect large-scale fields. In practice, the ...

  13. A simple approach to spectrally resolved fluorescence and bright field microscopy over select regions of interest

    OpenAIRE

    Dahlberg, Peter D.; Boughter, Christopher T.; Faruk, Nabil F.; Hong, Lu; Koh, Young Hoon; Reyer, Matthew A.; Shaiber, Alon; Sherani, Aiman; Zhang, Jiacheng; Jureller, Justin E.; Hammond, Adam T.

    2016-01-01

    A standard wide field inverted microscope was converted to a spatially selective spectrally resolved microscope through the addition of a polarizing beam splitter, a pair of polarizers, an amplitude-mode liquid crystal-spatial light modulator, and a USB spectrometer. The instrument is capable of simultaneously imaging and acquiring spectra over user defined regions of interest. The microscope can also be operated in a bright-field mode to acquire absorption spectra of micron scale objects. Th...

  14. Measurement of multilayer mirror reflectivity and stimulated emission in the XUV spectral region

    International Nuclear Information System (INIS)

    Keane, C.; Nam, C.H.; Meixler, L.; Milchberg, H.; Skinner, C.H.; Suckewer, S.; Voorhees, D.; Barbee, T.

    1986-03-01

    We present measurements of multilayer mirror reflectivity and stimulated emission in the XUV spectral region. A molybdenum-silicon multilayer mirror with 12% measured reflectivity at 182 A was found to produce a 120% enhancement of the C VI 182 A line (3 → 2 transition) in a strongly recombining plasma. No such enhancement of the CV 186.7 A line was seen, demonstrating amplification of stimulated emission at 182 A

  15. Spectral Analysis of Chinese Medicinal Herbs Based on Delayed Luminescence

    Directory of Open Access Journals (Sweden)

    Jingxiang Pang

    2016-01-01

    Full Text Available Traditional Chinese medicine (TCM plays a critical role in healthcare; however, it lacks scientific evidence to support the multidimensional therapeutic effects. These effects are based on experience, and, to date, there is no advanced tool to evaluate these experience based effects. In the current study, Chinese herbal materials classified with different cold and heat therapeutic properties, based on Chinese medicine principles, were investigated using spectral distribution, as well as the decay probability distribution based on delayed luminescence (DL. A detection system based on ultraweak biophoton emission was developed to determine the DL decay kinetics of the cold and heat properties of Chinese herbal materials. We constructed a mathematical model to fit the experimental data and characterize the properties of Chinese medicinal herbs with different parameters. The results demonstrated that this method has good reproducibility. Moreover, there is a significant difference (p<0.05 in the spectral distribution and the decay probability distribution of Chinese herbal materials with cold and heat properties. This approach takes advantage of the comprehensive nature of DL compared with more reductionist approaches and is more consistent with TCM principles, in which the core comprises holistic views.

  16. The volatile compound BinBase mass spectral database.

    Science.gov (United States)

    Skogerson, Kirsten; Wohlgemuth, Gert; Barupal, Dinesh K; Fiehn, Oliver

    2011-08-04

    Volatile compounds comprise diverse chemical groups with wide-ranging sources and functions. These compounds originate from major pathways of secondary metabolism in many organisms and play essential roles in chemical ecology in both plant and animal kingdoms. In past decades, sampling methods and instrumentation for the analysis of complex volatile mixtures have improved; however, design and implementation of database tools to process and store the complex datasets have lagged behind. The volatile compound BinBase (vocBinBase) is an automated peak annotation and database system developed for the analysis of GC-TOF-MS data derived from complex volatile mixtures. The vocBinBase DB is an extension of the previously reported metabolite BinBase software developed to track and identify derivatized metabolites. The BinBase algorithm uses deconvoluted spectra and peak metadata (retention index, unique ion, spectral similarity, peak signal-to-noise ratio, and peak purity) from the Leco ChromaTOF software, and annotates peaks using a multi-tiered filtering system with stringent thresholds. The vocBinBase algorithm assigns the identity of compounds existing in the database. Volatile compound assignments are supported by the Adams mass spectral-retention index library, which contains over 2,000 plant-derived volatile compounds. Novel molecules that are not found within vocBinBase are automatically added using strict mass spectral and experimental criteria. Users obtain fully annotated data sheets with quantitative information for all volatile compounds for studies that may consist of thousands of chromatograms. The vocBinBase database may also be queried across different studies, comprising currently 1,537 unique mass spectra generated from 1.7 million deconvoluted mass spectra of 3,435 samples (18 species). Mass spectra with retention indices and volatile profiles are available as free download under the CC-BY agreement (http://vocbinbase.fiehnlab.ucdavis.edu). The BinBase

  17. The volatile compound BinBase mass spectral database

    Directory of Open Access Journals (Sweden)

    Barupal Dinesh K

    2011-08-01

    Full Text Available Abstract Background Volatile compounds comprise diverse chemical groups with wide-ranging sources and functions. These compounds originate from major pathways of secondary metabolism in many organisms and play essential roles in chemical ecology in both plant and animal kingdoms. In past decades, sampling methods and instrumentation for the analysis of complex volatile mixtures have improved; however, design and implementation of database tools to process and store the complex datasets have lagged behind. Description The volatile compound BinBase (vocBinBase is an automated peak annotation and database system developed for the analysis of GC-TOF-MS data derived from complex volatile mixtures. The vocBinBase DB is an extension of the previously reported metabolite BinBase software developed to track and identify derivatized metabolites. The BinBase algorithm uses deconvoluted spectra and peak metadata (retention index, unique ion, spectral similarity, peak signal-to-noise ratio, and peak purity from the Leco ChromaTOF software, and annotates peaks using a multi-tiered filtering system with stringent thresholds. The vocBinBase algorithm assigns the identity of compounds existing in the database. Volatile compound assignments are supported by the Adams mass spectral-retention index library, which contains over 2,000 plant-derived volatile compounds. Novel molecules that are not found within vocBinBase are automatically added using strict mass spectral and experimental criteria. Users obtain fully annotated data sheets with quantitative information for all volatile compounds for studies that may consist of thousands of chromatograms. The vocBinBase database may also be queried across different studies, comprising currently 1,537 unique mass spectra generated from 1.7 million deconvoluted mass spectra of 3,435 samples (18 species. Mass spectra with retention indices and volatile profiles are available as free download under the CC-BY agreement (http

  18. Terahertz spectral unmixing based method for identifying gastric cancer

    Science.gov (United States)

    Cao, Yuqi; Huang, Pingjie; Li, Xian; Ge, Weiting; Hou, Dibo; Zhang, Guangxin

    2018-02-01

    At present, many researchers are exploring biological tissue inspection using terahertz time-domain spectroscopy (THz-TDS) techniques. In this study, based on a modified hard modeling factor analysis method, terahertz spectral unmixing was applied to investigate the relationships between the absorption spectra in THz-TDS and certain biomarkers of gastric cancer in order to systematically identify gastric cancer. A probability distribution and box plot were used to extract the distinctive peaks that indicate carcinogenesis, and the corresponding weight distributions were used to discriminate the tissue types. The results of this work indicate that terahertz techniques have the potential to detect different levels of cancer, including benign tumors and polyps.

  19. Impact of spectral nudging on the downscaling of tropical cyclones in regional climate simulations

    Science.gov (United States)

    Choi, Suk-Jin; Lee, Dong-Kyou

    2016-06-01

    This study investigated the simulations of three months of seasonal tropical cyclone (TC) activity over the western North Pacific using the Advanced Research WRF Model. In the control experiment (CTL), the TC frequency was considerably overestimated. Additionally, the tracks of some TCs tended to have larger radii of curvature and were shifted eastward. The large-scale environments of westerly monsoon flows and subtropical Pacific highs were unreasonably simulated. The overestimated frequency of TC formation was attributed to a strengthened westerly wind field in the southern quadrants of the TC center. In comparison with the experiment with the spectral nudging method, the strengthened wind speed was mainly modulated by large-scale flow that was greater than approximately 1000 km in the model domain. The spurious formation and undesirable tracks of TCs in the CTL were considerably improved by reproducing realistic large-scale atmospheric monsoon circulation with substantial adjustment between large-scale flow in the model domain and large-scale boundary forcing modified by the spectral nudging method. The realistic monsoon circulation took a vital role in simulating realistic TCs. It revealed that, in the downscaling from large-scale fields for regional climate simulations, scale interaction between model-generated regional features and forced large-scale fields should be considered, and spectral nudging is a desirable method in the downscaling method.

  20. A simple approach to spectrally resolved fluorescence and bright field microscopy over select regions of interest.

    Science.gov (United States)

    Dahlberg, Peter D; Boughter, Christopher T; Faruk, Nabil F; Hong, Lu; Koh, Young Hoon; Reyer, Matthew A; Shaiber, Alon; Sherani, Aiman; Zhang, Jiacheng; Jureller, Justin E; Hammond, Adam T

    2016-11-01

    A standard wide field inverted microscope was converted to a spatially selective spectrally resolved microscope through the addition of a polarizing beam splitter, a pair of polarizers, an amplitude-mode liquid crystal-spatial light modulator, and a USB spectrometer. The instrument is capable of simultaneously imaging and acquiring spectra over user defined regions of interest. The microscope can also be operated in a bright-field mode to acquire absorption spectra of micron scale objects. The utility of the instrument is demonstrated on three different samples. First, the instrument is used to resolve three differently labeled fluorescent beads in vitro. Second, the instrument is used to recover time dependent bleaching dynamics that have distinct spectral changes in the cyanobacteria, Synechococcus leopoliensis UTEX 625. Lastly, the technique is used to acquire the absorption spectra of CH 3 NH 3 PbBr 3 perovskites and measure differences between nanocrystal films and micron scale crystals.

  1. A simple approach to spectrally resolved fluorescence and bright field microscopy over select regions of interest

    Science.gov (United States)

    Dahlberg, Peter D.; Boughter, Christopher T.; Faruk, Nabil F.; Hong, Lu; Koh, Young Hoon; Reyer, Matthew A.; Shaiber, Alon; Sherani, Aiman; Zhang, Jiacheng; Jureller, Justin E.; Hammond, Adam T.

    2016-11-01

    A standard wide field inverted microscope was converted to a spatially selective spectrally resolved microscope through the addition of a polarizing beam splitter, a pair of polarizers, an amplitude-mode liquid crystal-spatial light modulator, and a USB spectrometer. The instrument is capable of simultaneously imaging and acquiring spectra over user defined regions of interest. The microscope can also be operated in a bright-field mode to acquire absorption spectra of micron scale objects. The utility of the instrument is demonstrated on three different samples. First, the instrument is used to resolve three differently labeled fluorescent beads in vitro. Second, the instrument is used to recover time dependent bleaching dynamics that have distinct spectral changes in the cyanobacteria, Synechococcus leopoliensis UTEX 625. Lastly, the technique is used to acquire the absorption spectra of CH3NH3PbBr3 perovskites and measure differences between nanocrystal films and micron scale crystals.

  2. Ground-based spectral measurements of solar radiation, (2)

    International Nuclear Information System (INIS)

    Murai, Keizo; Kobayashi, Masaharu; Goto, Ryozo; Yamauchi, Toyotaro

    1979-01-01

    A newly designed spectro-pyranometer was used for the measurement of the global (direct + diffuse) and the diffuse sky radiation reaching the ground. By the subtraction of the diffuse component from the global radiation, we got the direct radiation component which leads to the spectral distribution of the optical thickness (extinction coefficient) of the turbid atmosphere. The measurement of the diffuse sky radiation reveals the scattering effect of aerosols and that of the global radiation allows the estimation of total attenuation caused by scattering and absorption of aerosols. The effects of the aerosols are represented by the deviation of the real atmosphere measured from the Rayleigh atmosphere. By the combination of the measured values with those obtained by theoretical calculation for the model atmosphere, we estimated the amount of absorption by the aerosols. Very strong absorption in the ultraviolet region was recognized. (author)

  3. Impacts of using spectral nudging on regional climate model RCA4 simulations of the Arctic

    Directory of Open Access Journals (Sweden)

    P. Berg

    2013-06-01

    Full Text Available The performance of the Rossby Centre regional climate model RCA4 is investigated for the Arctic CORDEX (COordinated Regional climate Downscaling EXperiment region, with an emphasis on its suitability to be coupled to a regional ocean and sea ice model. Large biases in mean sea level pressure (MSLP are identified, with pronounced too-high pressure centred over the North Pole in summer of over 5 hPa, and too-low pressure in winter of a similar magnitude. These lead to biases in the surface winds, which will potentially lead to strong sea ice biases in a future coupled system. The large-scale circulation is believed to be the major reason for the biases, and an implementation of spectral nudging is applied to remedy the problems by constraining the large-scale components of the driving fields within the interior domain. It is found that the spectral nudging generally corrects for the MSLP and wind biases, while not significantly affecting other variables, such as surface radiative components, two-metre temperature and precipitation.

  4. Fabrication and Spectral Properties of Wood-Based Luminescent Nanocomposites

    Directory of Open Access Journals (Sweden)

    Xianjun Li

    2014-01-01

    Full Text Available Pressure impregnation pretreatment is a conventional method to fabricate wood-based nanocomposites. In this paper, the wood-based luminescent nanocomposites were fabricated with the method and its spectral properties were investigated. The results show that it is feasible to fabricate wood-based luminescent nanocomposites using microwave modified wood and nanophosphor powders. The luminescent strength is in positive correlation with the amount of phosphor powders dispersed in urea-formaldehyde resin. Phosphors absorb UV and blue light efficiently in the range of 400–470 nm and show a broad band of bluish-green emission centered at 500 nm, which makes them good candidates for potential blue-green luminescent materials.

  5. Spectral classification of medium-scale high-latitude F region plasma density irregularities

    International Nuclear Information System (INIS)

    Singh, M.; Rodriguez, P.; Szuszczewicz, E.P.; Sachs Freeman Associates, Bowie, MD)

    1985-01-01

    The high-latitude ionosphere represents a highly structured plasma. Rodriguez and Szuszczewicz (1984) reported a wide range of plasma density irregularities (150 km to 75 m) at high latitudes near 200 km. They have shown that the small-scale irregularities (7.5 km to 75 m) populated the dayside oval more often than the other phenomenological regions. It was suggested that in the lower F region the chemical recombination is fast enough to remove small-scale irregularities before convection can transport them large distances, leaving structured particle precipitation as the dominant source term for irregularities. The present paper provides the results of spectral analyses of pulsed plasma probe data collected in situ aboard the STP/S3-4 satellite during the period March-September 1978. A quantitative description of irregularity spectra in the high-latitude lower F region plasma density is given. 22 references

  6. Broadband cavity-enhanced absorption spectroscopy in the ultraviolet spectral region for measurements of nitrogen dioxide and formaldehyde

    Science.gov (United States)

    Washenfelder, R. A.; Attwood, A. R.; Flores, J. M.; Zarzana, K. J.; Rudich, Y.; Brown, S. S.

    2016-01-01

    Formaldehyde (CH2O) is the most abundant aldehyde in the atmosphere, and it strongly affects photochemistry through its photolysis. We describe simultaneous measurements of CH2O and nitrogen dioxide (NO2) using broadband cavity-enhanced absorption spectroscopy in the ultraviolet spectral region. The light source consists of a continuous-wave diode laser focused into a Xenon bulb to produce a plasma that emits high-intensity, broadband light. The plasma discharge is optically filtered and coupled into a 1 m optical cavity. The reflectivity of the cavity mirrors is 0.99930 ± 0.00003 (1- reflectivity = 700 ppm loss) at 338 nm, as determined from the known Rayleigh scattering of He and zero air. This mirror reflectivity corresponds to an effective path length of 1.43 km within the 1 m cell. We measure the cavity output over the 315-350 nm spectral region using a grating monochromator and charge-coupled device array detector. We use published reference spectra with spectral fitting software to simultaneously retrieve CH2O and NO2 concentrations. Independent measurements of NO2 standard additions by broadband cavity-enhanced absorption spectroscopy and cavity ring-down spectroscopy agree within 2 % (slope for linear fit = 1.02 ± 0.03 with r2 = 0.998). Standard additions of CH2O measured by broadband cavity-enhanced absorption spectroscopy and calculated based on flow dilution are also well correlated, with r2 = 0.9998. During constant mixed additions of NO2 and CH2O, the 30 s measurement precisions (1σ) of the current configuration were 140 and 210 pptv, respectively. The current 1 min detection limit for extinction measurements at 315-350 nm provides sufficient sensitivity for measurement of trace gases in laboratory experiments and ground-based field experiments. Additionally, the instrument provides highly accurate, spectroscopically based trace gas detection that may complement higher precision techniques based on non-absolute detection methods. In addition to

  7. Semiconductor lasers with a continuous tuning range above 100 nm in the nearest IR spectral region

    Energy Technology Data Exchange (ETDEWEB)

    Kostin, Yu O; Lobintsov, A A; Shramenko, M V [OOO ' Opton' , Moscow (Russian Federation); Ladugin, M A; Marmalyuk, A A [Open Joint-Stock Company M.F. Stel' makh Polyus Research Institute, Moscow (Russian Federation); Chamorovsky, A Yu [Superlum Ltd., Unit B3, Fota Point Enterprise Park, Carrigtwohill, Co Cork (Ireland); Yakubovich, S D [Moscow State Institute of Radio-Engineering, Electronics and Automation (Technical University), Moscow (Russian Federation)

    2015-08-31

    We have developed two new types of lasers based on quantum-confined semiconductor optical amplifiers with an acousto-optic tunable filter in an external fibre ring cavity. The lasers offer continuous wavelength tuning ranges from 780 to 885 and from 880 to 1010 nm, 20 mW of cw output power, and a tuning rate up to 10{sup 4} nm s{sup -1} at an instantaneous spectral linewidth less than 0.1 nm. (lasers)

  8. Achromatization In The 3 To 5 μm Spectral Region With Visible Light Transmitting Materials

    Science.gov (United States)

    McDowell, M. W.; Klee, H. W.

    1984-04-01

    The theoretical performances of several f/1.5 triplet lenses suitable for use in the 3 to 5um spectral region are compared. Examples are given in which all the materials used have a finite visible transmittance. As centering errors can thus be considerably reduced, it is expected that such a lens will in practice approach more closely its theoretical performance. These lenses are also considerably less sensitive to manufacturing tolerances as a result of lower index materials, and the use of low dn/dT materials offers other advantages over the more usual silicon-germanium combination.

  9. Bottomside sinusoidal irregularities in the equatorial F region. II - Cross-correlation and spectral analysis

    Science.gov (United States)

    Cragin, B. L.; Hanson, W. B.; Mcclure, J. P.; Valladares, C. E.

    1985-01-01

    Equatorial bottomside sinusoidal (BSS) irregularities have been studied by applying techniques of cross-correlation and spectral analysis to the Atmosphere Explorer data set. The phase of the cross-correlations of the plasma number density is discussed and the two drift velocity components observed using the retarding potential analyzer and ion drift meter on the satellite are discussed. Morphology is addressed, presenting the geographical distributions of the occurrence of BSS events for the equinoxes and solstices. Physical processes including the ion Larmor flux, interhemispheric plasma flows, and variations in the lower F region Pedersen conductivity are invoked to explain the findings.

  10. Ground-Based Correction of Remote-Sensing Spectral Imagery

    Science.gov (United States)

    Alder-Golden, Steven M.; Rochford, Peter; Matthew, Michael; Berk, Alexander

    2007-01-01

    Software has been developed for an improved method of correcting for the atmospheric optical effects (primarily, effects of aerosols and water vapor) in spectral images of the surface of the Earth acquired by airborne and spaceborne remote-sensing instruments. In this method, the variables needed for the corrections are extracted from the readings of a radiometer located on the ground in the vicinity of the scene of interest. The software includes algorithms that analyze measurement data acquired from a shadow-band radiometer. These algorithms are based on a prior radiation transport software model, called MODTRAN, that has been developed through several versions up to what are now known as MODTRAN4 and MODTRAN5 . These components have been integrated with a user-friendly Interactive Data Language (IDL) front end and an advanced version of MODTRAN4. Software tools for handling general data formats, performing a Langley-type calibration, and generating an output file of retrieved atmospheric parameters for use in another atmospheric-correction computer program known as FLAASH have also been incorporated into the present soft-ware. Concomitantly with the soft-ware described thus far, there has been developed a version of FLAASH that utilizes the retrieved atmospheric parameters to process spectral image data.

  11. Narrowband spectral filter based on biconical tapered fiber

    Science.gov (United States)

    Celaschi, Sergio; Malheiros-Silveira, Gilliard N.

    2018-02-01

    The ease of fabrication and compactness of devices based on tapered optical fibers contribute to its potential using in several applications ranging from telecommunication components to sensing devices. In this work, we proposed, fabricated, and characterized a spectral filter made of biconical taper from a coaxial optical fiber. This filter is defined by adiabatically tapering a depressed-cladding fiber. The adiabatic taper profile obtained during fabrication prevents the interference of other modes than HE11 and HE12 ones, which play the main role for the beating phenomenon and the filter response. The evolution of the fiber shapes during the pulling was modeled by two coupled partial differential equations, which relate the normalized cross-section area, and the axial velocity of the fiber elongation. These equations govern the mass and axial momentum conservation. The numerical results of the filter characteristics are in good accordance with the experimental ones. The filter was packaged in order to let it ready for using in optical communication bands. The characteristics are: free spectral range (FSR) of 6.19 nm, insertion loss bellow 0.5 dB, and isolation > 20 dB at C-band. Its transmission spectrum extends from 1200 to 1600 nm where the optical fiber core supports monomode transmission. Such characteristics may also be interesting to be applied in sensing applications. We show preliminary numerical results assuming a biconic taper embedded into a dielectric media, showing promising results for electro-optic sensing applications.

  12. Cloud-based processing of multi-spectral imaging data

    Science.gov (United States)

    Bernat, Amir S.; Bolton, Frank J.; Weiser, Reuven; Levitz, David

    2017-03-01

    Multispectral imaging holds great promise as a non-contact tool for the assessment of tissue composition. Performing multi - spectral imaging on a hand held mobile device would allow to bring this technology and with it knowledge to low resource settings to provide a state of the art classification of tissue health. This modality however produces considerably larger data sets than white light imaging and requires preliminary image analysis for it to be used. The data then needs to be analyzed and logged, while not requiring too much of the system resource or a long computation time and battery use by the end point device. Cloud environments were designed to allow offloading of those problems by allowing end point devices (smartphones) to offload computationally hard tasks. For this end we present a method where the a hand held device based around a smartphone captures a multi - spectral dataset in a movie file format (mp4) and compare it to other image format in size, noise and correctness. We present the cloud configuration used for segmenting images to frames where they can later be used for further analysis.

  13. Study of the spectral and energy characteristics of lasing in the green spectral region by lithium fluoride with radiation color centers

    Energy Technology Data Exchange (ETDEWEB)

    Voitovich, A.P.; Kalinov, V.S.; Mikhnov, S.A.; Ovseichuk, S.I.

    1987-06-01

    The spectral and energy characteristics of lasers utilizing lithium fluoride with F2 and F3(+) color centers in transverse and longitudinal pumping schemes are studied. The feasibility of obtaining stable narrow-band radiation in the 510-570 nm range using a selective resonator is demonstrated. Consideration is given to the effect of lithium-fluoride crystal processing by excimer laser radiation at a wavelength of 308 nm on the spectroscopic and lasing characteristics of the F3(+) color center. After this processing, the laser efficiency in the green spectral region increases by more than a factor of two (reaching an efficiency of 14 percent). 7 references.

  14. Brown carbon absorption in the red and near-infrared spectral region

    Science.gov (United States)

    Hoffer, András; Tóth, Ádám; Pósfai, Mihály; Eddy Chung, Chul; Gelencsér, András

    2017-06-01

    Black carbon (BC) aerosols have often been assumed to be the only light-absorbing carbonaceous particles in the red and near-infrared spectral regions of solar radiation in the atmosphere. Here we report that tar balls (a specific type of organic aerosol particles from biomass burning) do absorb red and near-infrared radiation significantly. Tar balls were produced in a laboratory experiment, and their chemical and optical properties were measured. The absorption of these particles in the range between 470 and 950 nm was measured with an aethalometer, which is widely used to measure atmospheric aerosol absorption. We find that the absorption coefficient of tar balls at 880 nm is more than 10 % of that at 470 nm. The considerable absorption of red and infrared light by tar balls also follows from their relatively low absorption Ångström coefficient (and significant mass absorption coefficient) in the spectral range between 470 and 950 nm. Our results support the previous finding that tar balls may play an important role in global warming. Due to the non-negligible absorption of tar balls in the near-infrared region, the absorption measured in the field at near-infrared wavelengths cannot solely be due to soot particles.

  15. Laser's calibration of an AOTF-based spectral colorimeter

    Science.gov (United States)

    Emelianov, Sergey P.; Khrustalev, Vladimir N.; Kochin, Leonid B.; Polosin, Lev L.

    2003-06-01

    The paper is devoted to expedients of AOTF spectral colorimeters calibration. The spectrometer method of color values measuring with reference to spectral colorimeters on AOTF surveyed. The theoretical exposition of spectrometer data processing expedients is offered. The justified source of radiation choice, suitable for calibration of spectral colorimeters is carried out. The experimental results for different acousto-optical mediums and modes of interaction are submitted.

  16. Next Generation UAV Based Spectral Systems for Environmental Monitoring

    Data.gov (United States)

    National Aeronautics and Space Administration — At present, UAVs used in environmental monitoring mostly collect low spectral resolution imagery, capable of retrieving canopy greenness or properties related water...

  17. Spatio-Spectral Method for Estimating Classified Regions with High Confidence using MODIS Data

    International Nuclear Information System (INIS)

    Katiyal, Anuj; Rajan, Dr K S

    2014-01-01

    In studies like change analysis, the availability of very high resolution (VHR)/high resolution (HR) imagery for a particular period and region is a challenge due to the sensor revisit times and high cost of acquisition. Therefore, most studies prefer lower resolution (LR) sensor imagery with frequent revisit times, in addition to their cost and computational advantages. Further, the classification techniques provide us a global estimate of the class accuracy, which limits its utility if the accuracy is low. In this work, we focus on the sub-classification problem of LR images and estimate regions of higher confidence than the global classification accuracy within its classified region. The spectrally classified data was mined into spatially clustered regions and further refined and processed using statistical measures to arrive at local high confidence regions (LHCRs), for every class. Rabi season MODIS data of January 2006 and 2007 was used for this study and the evaluation of LHCR was done using the APLULC 2005 classified data. For Jan-2007, the global class accuracies for water bodies (WB), forested regions (FR) and Kharif crops and barren lands (KB) were 89%, 71.7% and 71.23% respectively, while the respective LHCRs had accuracies of 96.67%, 89.4% and 80.9% covering an area of 46%, 29% and 14.5% of the initially classified areas. Though areas are reduced, LHCRs with higher accuracies help in extracting more representative class regions. Identification of such regions can facilitate in improving the classification time and processing for HR images when combined with the more frequently acquired LR imagery, isolate pure vs. mixed/impure pixels and as training samples locations for HR imagery

  18. On the potential of the 2041–2047 nm spectral region for remote sensing of atmospheric CO2 isotopologues

    International Nuclear Information System (INIS)

    Reuter, M.; Bovensmann, H.; Buchwitz, M.; Burrows, J.P.; Deutscher, N.M.; Heymann, J.; Rozanov, A.; Schneising, O.; Suto, H.; Toon, G.C.; Warneke, T.

    2012-01-01

    Pressing open questions about the carbon cycle can be addressed with precise measurements of the three most abundant CO 2 isotopologues 16 O 12 C 16 O, 16 O 13 C 16 O, and 16 O 12 C 18 O. Such measurements can, e.g., help to further constrain oceanic and biospheric net fluxes or to differentiate between the gross biospheric fluxes photosynthesis and respiration. The 2041–2047nm (about 4885–4900cm −1 ) spectral region contains separated absorption lines of the three most abundant CO 2 isotopologues. Their spectral properties make this spectral region well suited for the use of a light path proxy method for the retrieval of δ 13 C and δ 18 O (the ratio of heavier to lighter isotopologues relative to a standard). An optimal estimation based light path proxy retrieval for δ 13 C and δ 18 O has been set up, applicable to GOSAT (Greenhouse gases Observing Satellite) and ground-based FTS (Fourier transform spectrometer) measurements. Initial results show that it is possible to retrieve δ 13 C and δ 18 O from ground-based FTS instruments with a precision of 0.6–1.6‰ and from GOSAT with a precision of about 30‰. Comparison of the achievable precision with the expected atmospheric signals shows that ground-based FTS remote sensing measurements have the potential to gain valuable information on δ 13 C and δ 18 O if averaging a sufficient number of measurements. It seems unlikely that this applies also to GOSAT because of the lower precision and a conceptual larger sensitivity to scattering related errors in satellite viewing geometry. -- Highlights: ► The 2041–2047 nm region is suited for remote sensing atmospheric CO 2 isotopologues. ► A δ 13 C and δ 18 O retrieval was set up for ground-based FTS and the GOSAT satellite. ► The retrieval precision of δ 13 C and δ 18 O is about 0.6–1.6‰ (FTS) and 30‰ (GOSAT). ► FTS measurements can give valuable information on atmospheric δ 13 C and δ 18 O.

  19. Spectral cumulus parameterization based on cloud-resolving model

    Science.gov (United States)

    Baba, Yuya

    2018-02-01

    We have developed a spectral cumulus parameterization using a cloud-resolving model. This includes a new parameterization of the entrainment rate which was derived from analysis of the cloud properties obtained from the cloud-resolving model simulation and was valid for both shallow and deep convection. The new scheme was examined in a single-column model experiment and compared with the existing parameterization of Gregory (2001, Q J R Meteorol Soc 127:53-72) (GR scheme). The results showed that the GR scheme simulated more shallow and diluted convection than the new scheme. To further validate the physical performance of the parameterizations, Atmospheric Model Intercomparison Project (AMIP) experiments were performed, and the results were compared with reanalysis data. The new scheme performed better than the GR scheme in terms of mean state and variability of atmospheric circulation, i.e., the new scheme improved positive bias of precipitation in western Pacific region, and improved positive bias of outgoing shortwave radiation over the ocean. The new scheme also simulated better features of convectively coupled equatorial waves and Madden-Julian oscillation. These improvements were found to be derived from the modification of parameterization for the entrainment rate, i.e., the proposed parameterization suppressed excessive increase of entrainment, thus suppressing excessive increase of low-level clouds.

  20. Determine the optimum spectral reflectance of juniper and pistachio in arid and semi-arid region

    Science.gov (United States)

    Fadaei, Hadi; Suzuki, Rikie

    2012-11-01

    Arid and semi-arid areas of northeast Iran cover about 3.4 million ha are populated by two main tree species, the broadleaf Pistacia vera. L (pistachio) and the conifer Juniperus excelsa ssp. polycarpos (Persian juniper). Natural stands of pistachio in Iran are not only environmentally important but genetically essential as seed sources for pistachio production in orchards. In this study, we estimated the optimum spectral reflectance of juniper forests and natural pistachio stands using remote sensing to help in the sustainable management and production of pistachio in Iran. In this research spectral reflectance are able to specify of multispectral from Advanced Land Observing Satellite (ALOS) that provided by JAXA. These data included PRISM is a panchromatic radiometer with a 2.5 m spatial resolution at nadir, has one band with a wavelength of 0.52-0.77 μm and AVNIR-2 is a visible and near infrared radiometer for observing land and coastal zones with a 10 m spatial resolution at nadir, has four multispectral bands: blue (0.42-0.50 μm), green (0.52-0.60 μm), red (0.61-0.69 μm), and near infrared (0.76-0.89 μm). Total ratio vegetation index (TRVI) of optimum spectral reflectance of juniper and pistachio have been evaluated. The result of TRVI for Pistachio and juniper were (R2= 0.71 and 0.55). I hope this research can provide decision of managers to helping sustainable management for arid and semi-arid regions in Iran.

  1. Spectral damping scaling factors for shallow crustal earthquakes in active tectonic regions

    Science.gov (United States)

    Rezaeian, Sanaz; Bozorgnia, Yousef; Idriss, I.M.; Campbell, Kenneth; Abrahamson, Norman; Silva, Walter

    2012-01-01

    Ground motion prediction equations (GMPEs) for elastic response spectra, including the Next Generation Attenuation (NGA) models, are typically developed at a 5% viscous damping ratio. In reality, however, structural and non-structural systems can have damping ratios other than 5%, depending on various factors such as structural types, construction materials, level of ground motion excitations, among others. This report provides the findings of a comprehensive study to develop a new model for a Damping Scaling Factor (DSF) that can be used to adjust the 5% damped spectral ordinates predicted by a GMPE to spectral ordinates with damping ratios between 0.5 to 30%. Using the updated, 2011 version of the NGA database of ground motions recorded in worldwide shallow crustal earthquakes in active tectonic regions (i.e., the NGA-West2 database), dependencies of the DSF on variables including damping ratio, spectral period, moment magnitude, source-to-site distance, duration, and local site conditions are examined. The strong influence of duration is captured by inclusion of both magnitude and distance in the DSF model. Site conditions are found to have less significant influence on DSF and are not included in the model. The proposed model for DSF provides functional forms for the median value and the logarithmic standard deviation of DSF. This model is heteroscedastic, where the variance is a function of the damping ratio. Damping Scaling Factor models are developed for the “average” horizontal ground motion components, i.e., RotD50 and GMRotI50, as well as the vertical component of ground motion.

  2. Photoconductivity of vanadium-doped lead telluride in the terahertz spectral region

    Energy Technology Data Exchange (ETDEWEB)

    Artamkin, A. I.; Dobrovolsky, A. A.; Vinokurov, A. A.; Zlomanov, V. P. [Moscow State University (Russian Federation); Danilov, S. N. [University of Regensburg (Germany); Bel' kov, V. V. [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation); Ryabova, L. I.; Khokhlov, D. R., E-mail: khokhlov@mig.phys.msu.ru [Moscow State University (Russian Federation)

    2013-03-15

    It is shown that PbTe:V single crystals are photosensitive in the terahertz spectral region up to the wavelength 280 {mu}m. The measurements are conducted in the temperature range from 8 to 300 K. In this temperature range, the dark conductivity of the crystals exhibits the activation character of the temperature dependence and varies by four orders of magnitude, which is due to Fermi-level pinning 20 meV below the bottom of the conduction band. As the temperature is elevated and, correspondingly, the conductivity increases, the amplitude of the photoresponse substantially increases. This result is interpreted in the context of the model that takes into account significant broadening of the vanadium impurity level and its shift to the bottom of the conduction band with increasing temperature.

  3. Spectral colors capture and reproduction based on digital camera

    Science.gov (United States)

    Chen, Defen; Huang, Qingmei; Li, Wei; Lu, Yang

    2018-01-01

    The purpose of this work is to develop a method for the accurate reproduction of the spectral colors captured by digital camera. The spectral colors being the purest color in any hue, are difficult to reproduce without distortion on digital devices. In this paper, we attempt to achieve accurate hue reproduction of the spectral colors by focusing on two steps of color correction: the capture of the spectral colors and the color characterization of digital camera. Hence it determines the relationship among the spectral color wavelength, the RGB color space of the digital camera device and the CIEXYZ color space. This study also provides a basis for further studies related to the color spectral reproduction on digital devices. In this paper, methods such as wavelength calibration of the spectral colors and digital camera characterization were utilized. The spectrum was obtained through the grating spectroscopy system. A photo of a clear and reliable primary spectrum was taken by adjusting the relative parameters of the digital camera, from which the RGB values of color spectrum was extracted in 1040 equally-divided locations. Calculated using grating equation and measured by the spectrophotometer, two wavelength values were obtained from each location. The polynomial fitting method for the camera characterization was used to achieve color correction. After wavelength calibration, the maximum error between the two sets of wavelengths is 4.38nm. According to the polynomial fitting method, the average color difference of test samples is 3.76. This has satisfied the application needs of the spectral colors in digital devices such as display and transmission.

  4. Spectral resolution enhancement of Fourier-transform spectrometer based on orthogonal shear interference using Wollaston prism

    Science.gov (United States)

    Cong, Lin-xiao; Huang, Min; Cai, Qi-sheng

    2017-10-01

    In this paper, a multi-line interferogram stitching method based on orthogonal shear using the Wollaston prism(WP) was proposed with a 2D projection interferogram recorded through the rotation of CCD, making the spectral resolution of Fourier-Transform spectrometer(FTS) of a limited spatial size increase by at least three times. The fringes on multi-lines were linked with the pixels of equal optical path difference (OPD). Ideally, the error of sampled phase within one pixel was less than half the wavelength, ensuring consecutive values in the over-sampled dimension while aliasing in another. In the simulation, with the calibration of 1.064μm, spectral lines at 1.31μm and 1.56μm of equal intensity were tested and observed. The result showed a bias of 0.13% at 1.31μm and 1.15% at 1.56μm in amplitude, and the FWHM at 1.31μm reduced from 25nm to 8nm after the sample points increased from 320 to 960. In the comparison of reflectance spectrum of carnauba wax within near infrared(NIR) band, the absorption peak at 1.2μm was more obvious and zoom of the band 1.38 1.43μm closer to the reference, although some fluctuation was in the short-wavelength region arousing the spectral crosstalk. In conclusion, with orthogonal shear based on the rotation of the CCD relative to the axis of WP, the spectral resolution of static FTS was enhanced by the projection of fringes to the grid coordinates and stitching the interferograms into a larger OPD, which showed the advantages of cost and miniaturization in the space-constrained NIR applications.

  5. Simulation and analysis of Au-MgF2 structure in plasmonic sensor in near infrared spectral region

    Science.gov (United States)

    Sharma, Anuj K.

    2018-05-01

    Plasmonic sensor based on metal-dielectric combination of gold and MgF2 layers is studied in near infrared (NIR) spectral region. An emphasis is given on the effect of variable thickness of MgF2 layer in combination with operating wavelength and gold layer thickness on the sensor's performance in NIR. It is established that the variation in MgF2 thickness in connection with plasmon penetration depth leads to significant variation in sensor's performance. The analysis leads to a conclusion that taking smaller values of MgF2 layer thickness and operating at longer NIR wavelength leads to enhanced sensing performance. Also, fluoride glass can provide better sensing performance than chalcogenide glass and silicon substrate.

  6. Identification of Spectral Regions for Quantification of Red Wine Tannins with Fourier Transform Mid-Infrared Spectroscopy

    DEFF Research Database (Denmark)

    Jensen, Jacob Skibsted; Egebo, Max; Meyer, Anne S.

    2008-01-01

    Accomplishment of fast tannin measurements is receiving increased interest as tannins are important for the mouthfeel and color properties of red wines. Fourier transform mid-infrared spectroscopy allows fast measurement of different wine components, but quantification of tannins is difficult due...... to interferences from spectral responses of other wine components. Four different variable selection tools were investigated for the identification of the most important spectral regions which would allow quantification of tannins from the spectra using partial least-squares regression. The study included...... to be particularly important for tannin quantification. The spectral regions identified from the variable selection methods were used to develop calibration models. All four variable selection methods identified regions that allowed an improved quantitative prediction of tannins (RMSEP = 69−79 mg of CE/L; r = 0...

  7. Bulk mineralogy of the NE Syrtis and Jezero crater regions of Mars derived through thermal infrared spectral analyses

    Science.gov (United States)

    Salvatore, M. R.; Goudge, T. A.; Bramble, M. S.; Edwards, C. S.; Bandfield, J. L.; Amador, E. S.; Mustard, J. F.; Christensen, P. R.

    2018-02-01

    We investigated the area to the northwest of the Isidis impact basin (hereby referred to as "NW Isidis") using thermal infrared emission datasets to characterize and quantify bulk surface mineralogy throughout this region. This area is home to Jezero crater and the watershed associated with its two deltaic deposits in addition to NE Syrtis and the strong and diverse visible/near-infrared spectral signatures observed in well-exposed stratigraphic sections. The spectral signatures throughout this region show a diversity of primary and secondary surface mineralogies, including olivine, pyroxene, smectite clays, sulfates, and carbonates. While previous thermal infrared investigations have sought to characterize individual mineral groups within this region, none have systematically assessed bulk surface mineralogy and related these observations to visible/near-infrared studies. We utilize an iterative spectral unmixing method to statistically evaluate our linear thermal infrared spectral unmixing models to derive surface mineralogy. All relevant primary and secondary phases identified in visible/near-infrared studies are included in the unmixing models and their modeled spectral contributions are discussed in detail. While the stratigraphy and compositional diversity observed in visible/near-infrared spectra are much better exposed and more diverse than most other regions of Mars, our thermal infrared analyses suggest the dominance of basaltic compositions with less observed variability in the amount and diversity of alteration phases. These results help to constrain the mineralogical context of these previously reported visible/near-infrared spectral identifications. The results are also discussed in the context of future in situ investigations, as the NW Isidis region has long been promoted as a region of paleoenvironmental interest on Mars.

  8. Photosensitive in wide spectral region composites based on polyphenylenevinylene

    Czech Academy of Sciences Publication Activity Database

    Syromyatnikov, V.; Pomaz, I.; Verbitsky, A.; Vertsimakha, Ya.; Nešpůrek, Stanislav; Pochekaylov, Sergey

    2009-01-01

    Roč. 12, č. 1 (2009), s. 1-7 ISSN 1605-6582 EU Projects: European Commission(XE) 35859 - BIMORE Institutional research plan: CEZ:AV0Z40500505 Keywords : composite * photovoltage * polymer * organic dye * film Subject RIV: CD - Macromolecular Chemistry

  9. Directional Canopy Emissivity Estimation Based on Spectral Invariants

    Science.gov (United States)

    Guo, M.; Cao, B.; Ren, H.; Yongming, D.; Peng, J.; Fan, W.

    2017-12-01

    Land surface emissivity is a crucial parameter for estimating land surface temperature from remote sensing data and also plays an important role in the physical process of surface energy and water balance from local to global scales. To our knowledge, the emissivity varies with surface type and cover. As for the vegetation, its canopy emissivity is dependent on vegetation types, viewing zenith angle and structure that changes in different growing stages. Lots of previous studies have focused on the emissivity model, but few of them are analytic and suited to different canopy structures. In this paper, a new physical analytic model is proposed to estimate the directional emissivity of homogenous vegetation canopy based on spectral invariants. The initial model counts the directional absorption in six parts: the direct absorption of the canopy and the soil, the absorption of the canopy and soil after a single scattering and after multiple scattering within the canopy-soil system. In order to analytically estimate the emissivity, the pathways of photons absorbed in the canopy-soil system are traced using the re-collision probability in Fig.1. After sensitive analysis on the above six absorptions, the initial complicated model was further simplified as a fixed mathematic expression to estimate the directional emissivity for vegetation canopy. The model was compared with the 4SAIL model, FRA97 model, FRA02 model and DART model in Fig.2, and the results showed that the FRA02 model is significantly underestimated while the FRA97 model is a little underestimated, on basis of the new model. On the contrary, the emissivity difference between the new model with the 4SAIL model and DART model was found to be less than 0.002. In general, since the new model has the advantages of mathematic expression with accurate results and clear physical meaning, the model is promising to be extended to simulate the directional emissivity for the discrete canopy in further study.

  10. Water vapor absorption coefficients in the 8-13-micron spectral region - A critical review

    Science.gov (United States)

    Grant, William B.

    1990-01-01

    Measurements of water vapor absorption coefficients in the thermal IR atmospheric window (8-13 microns) during the past 20 years obtained by a variety of techniques are reviewed for consistency and compared with computed values based on the AFGL spectral data tapes. The methods of data collection considered were atmospheric long path absorption with a CO2 laser or a broadband source and filters, a White cell and a CO2 laser or a broadband source and a spectrometer, and a spectrophone with a CO2 laser. Advantages and disadvantages of each measurement approach are given as a guide to further research. Continuum absorption has apparently been measured accurately to about the 5-10 percent level in five of the measurements reported.

  11. Mare Crisium - Regional stratigraphy and geologic history. [from spectral reflectivities of Lunik 24 samples

    Science.gov (United States)

    Adams, J. B.; Head, J. W., III; Mccord, T. B.; Pieters, C.; Zisk, S.

    1978-01-01

    Spectral reflectance measurements of five Luna 24 samples and new telescopic reflectance spectra of 10-20 km areas of seven sites in Mare Crisium have been used to calibrate multispectral images of mare units. Based on these data, three major mare units are defined in the Crisium basin and their stratigraphy is interpreted. The oldest mare unit is exposed in the ejecta of the craters Picard and Peirce and along the outer edge of the southeastern part of the basin. The next younger unit includes the Luna 24 site and generally follows a topographic annulus along the basin margin. The youngest mare unit occupies the central part of the basin. It is concluded that subsidence occurred throughout the emplacement of mare units, including extensive warping and downfaulting of the inner part of the Crisium basin.

  12. On the instability of a modified cup-burner flame in the infrared spectral region

    Directory of Open Access Journals (Sweden)

    Petr Bitala

    2016-03-01

    Full Text Available This study describes the modification of a standardised cup-burner apparatus. The replacement of the original glass chimney is performed by shielding a nitrogen co-flow enabled measurement at a wavelength of 3.9 μm. This modification, together with a special arrangement of the measuring system (spectral filtering, data acquisition and post-processing, permitted the observation of various types of hydrodynamic instabilities, including transition states. The advantages of our arrangement are demonstrated with an ethylene non-premixed flame with high sooting tendency. Two known modes of hydrodynamic instability (varicose and sinuous that occur in buoyant flames were studied and described quantitatively. Based on the intensity of the infrared emissions, we identified and qualitatively described the modes of periodic hydrodynamic instability that are accompanied by flame tip opening, which has not been observed for this type of flame.

  13. Spectral nudging to eliminate the effects of domain position and geometry in regional climate model simulations

    Science.gov (United States)

    Miguez-Macho, Gonzalo; Stenchikov, Georgiy L.; Robock, Alan

    2004-07-01

    It is well known that regional climate simulations are sensitive to the size and position of the domain chosen for calculations. Here we study the physical mechanisms of this sensitivity. We conducted simulations with the Regional Atmospheric Modeling System (RAMS) for June 2000 over North America at 50 km horizontal resolution using a 7500 km × 5400 km grid and NCEP/NCAR reanalysis as boundary conditions. The position of the domain was displaced in several directions, always maintaining the U.S. in the interior, out of the buffer zone along the lateral boundaries. Circulation biases developed a large scale structure, organized by the Rocky Mountains, resulting from a systematic shifting of the synoptic wave trains that crossed the domain. The distortion of the large-scale circulation was produced by interaction of the modeled flow with the lateral boundaries of the nested domain and varied when the position of the grid was altered. This changed the large-scale environment among the different simulations and translated into diverse conditions for the development of the mesoscale processes that produce most of precipitation for the Great Plains in the summer season. As a consequence, precipitation results varied, sometimes greatly, among the experiments with the different grid positions. To eliminate the dependence of results on the position of the domain, we used spectral nudging of waves longer than 2500 km above the boundary layer. Moisture was not nudged at any level. This constrained the synoptic scales to follow reanalysis while allowing the model to develop the small-scale dynamics responsible for the rainfall. Nudging of the large scales successfully eliminated the variation of precipitation results when the grid was moved. We suggest that this technique is necessary for all downscaling studies with regional models with domain sizes of a few thousand kilometers and larger embedded in global models.

  14. Identification of spectral regions for the quantification of red wine tannins with fourier transform mid-infrared spectroscopy.

    Science.gov (United States)

    Jensen, Jacob S; Egebo, Max; Meyer, Anne S

    2008-05-28

    Accomplishment of fast tannin measurements is receiving increased interest as tannins are important for the mouthfeel and color properties of red wines. Fourier transform mid-infrared spectroscopy allows fast measurement of different wine components, but quantification of tannins is difficult due to interferences from spectral responses of other wine components. Four different variable selection tools were investigated for the identification of the most important spectral regions which would allow quantification of tannins from the spectra using partial least-squares regression. The study included the development of a new variable selection tool, iterative backward elimination of changeable size intervals PLS. The spectral regions identified by the different variable selection methods were not identical, but all included two regions (1485-1425 and 1060-995 cm(-1)), which therefore were concluded to be particularly important for tannin quantification. The spectral regions identified from the variable selection methods were used to develop calibration models. All four variable selection methods identified regions that allowed an improved quantitative prediction of tannins (RMSEP = 69-79 mg of CE/L; r = 0.93-0.94) as compared to a calibration model developed using all variables (RMSEP = 115 mg of CE/L; r = 0.87). Only minor differences in the performance of the variable selection methods were observed.

  15. High spatial and spectral resolution measurements of Jupiter's auroral regions using Gemini-North-TEXES

    Science.gov (United States)

    Sinclair, J. A.; Orton, G. S.; Greathouse, T. K.; Lacy, J.; Giles, R.; Fletcher, L. N.; Vogt, M.; Irwin, P. G.

    2017-12-01

    Jupiter exhibits auroral emission at a multitude of wavelengths. Auroral emission at X-ray, ultraviolet and near-infrared wavelengths demonstrate the precipitation of ion and electrons in Jupiter's upper atmosphere, at altitudes exceeding 250 km above the 1-bar level. Enhanced mid-infrared emission of CH4, C2H2, C2H4 and further hydrocarbons is also observed coincident with Jupiter's auroral regions. Retrieval analyses of infrared spectra from IRTF-TEXES (Texas Echelon Cross Echelle Spectrograph on NASA's Infrared Telescope Facility) indicate strong heating at the 1-mbar level and evidence of ion-neutral chemistry, which enriches the abundances of unsaturated hydrocarbons (Sinclair et al., 2017b, doi:10.1002/2017GL073529, Sinclair et al., 2017c (under review)). The extent to which these phenomena in the stratosphere are correlated and coupled physically with the shorter-wavelength auroral emission originating from higher altitudes has been a challenge due to the limited spatial resolution available on the IRTF. Smaller-scale features observed in the near-infrared and ultraviolet emission, such as the main `oval', transient `swirls' and dusk-active regions within the main oval (e.g. Stallard et al., 2014, doi:10.1016/j/Icarus.2015.12.044, Nichols et al., 2017, doi: 10.1002/2017GL073029) are potentially being blurred in the mid-infrared by the diffraction-limited resolution (0.7") of IRTF's 3-metre primary aperture. However, on March 17-19th 2017, we obtained spectral measurements of H2 S(1), CH4, C2H2, C2H4 and C2H6 emission of Jupiter's high latitudes using TEXES on Gemini-North, which has a 8-metre primary aperture. This rare opportunity combines the superior spectral resolving power of TEXES and the high spatial resolution provided by Gemini-North's 8-metre aperture. We will perform a retrieval analyses to determine the 3D distributions of temperature, C2H2, C2H4 and C2H6. The morphology will be compared with near-contemporaneous measurements of H3+ emission from

  16. A neural network based methodology to predict site-specific spectral acceleration values

    Science.gov (United States)

    Kamatchi, P.; Rajasankar, J.; Ramana, G. V.; Nagpal, A. K.

    2010-12-01

    A general neural network based methodology that has the potential to replace the computationally-intensive site-specific seismic analysis of structures is proposed in this paper. The basic framework of the methodology consists of a feed forward back propagation neural network algorithm with one hidden layer to represent the seismic potential of a region and soil amplification effects. The methodology is implemented and verified with parameters corresponding to Delhi city in India. For this purpose, strong ground motions are generated at bedrock level for a chosen site in Delhi due to earthquakes considered to originate from the central seismic gap of the Himalayan belt using necessary geological as well as geotechnical data. Surface level ground motions and corresponding site-specific response spectra are obtained by using a one-dimensional equivalent linear wave propagation model. Spectral acceleration values are considered as a target parameter to verify the performance of the methodology. Numerical studies carried out to validate the proposed methodology show that the errors in predicted spectral acceleration values are within acceptable limits for design purposes. The methodology is general in the sense that it can be applied to other seismically vulnerable regions and also can be updated by including more parameters depending on the state-of-the-art in the subject.

  17. Spectral embedding based active contour (SEAC): application to breast lesion segmentation on DCE-MRI

    Science.gov (United States)

    Agner, Shannon C.; Xu, Jun; Rosen, Mark; Karthigeyan, Sudha; Englander, Sarah; Madabhushi, Anant

    2011-03-01

    Spectral embedding (SE), a graph-based manifold learning method, has previously been shown to be useful in high dimensional data classification. In this work, we present a novel SE based active contour (SEAC) segmentation scheme and demonstrate its applications in lesion segmentation on breast dynamic contrast enhance magnetic resonance imaging (DCE-MRI). In this work, we employ SE on DCE-MRI on a per voxel basis to embed the high dimensional time series intensity vector into a reduced dimensional space, where the reduced embedding space is characterized by the principal eigenvectors. The orthogonal eigenvector-based data representation allows for computation of strong tensor gradients in the spectrally embedded space and also yields improved region statistics that serve as optimal stopping criteria for SEAC. We demonstrate both analytically and empirically that the tensor gradients in the spectrally embedded space are stronger than the corresponding gradients in the original grayscale intensity space. On a total of 50 breast DCE-MRI studies, SEAC yielded a mean absolute difference (MAD) of 3.2+/-2.1 pixels and mean Dice similarity coefficient (DSC) of 0.74+/-0.13 compared to manual ground truth segmentation. An active contour in conjunction with fuzzy c-means (FCM+AC), a commonly used segmentation method for breast DCE-MRI, produced a corresponding MAD of 7.2+/-7.4 pixels and mean DSC of 0.58+/-0.32. In conjunction with a set of 6 quantitative morphological features automatically extracted from the SEAC derived lesion boundary, a support vector machine (SVM) classifier yielded an area under the curve (AUC) of 0.73, for discriminating between 10 benign and 30 malignant lesions; the corresponding SVM classifier with the FCM+AC derived morphological features yielded an AUC of 0.65.

  18. Improving quantum efficiency and spectral resolution of a CCD through direct manipulation of the depletion region

    Science.gov (United States)

    Brown, Craig; Ambrosi, Richard M.; Abbey, Tony; Godet, Olivier; O'Brien, R.; Turner, M. J. L.; Holland, Andrew; Pool, Peter J.; Burt, David; Vernon, David

    2008-07-01

    Future generations of X-ray astronomy instruments will require position sensitive detectors in the form of charge-coupled devices (CCDs) for X-ray spectroscopy and imaging with the ability to probe the X-ray universe with greater efficiency. This will require the development of CCDs with structures that will improve their quantum efficiency over the current state of the art. The quantum efficiency improvements would have to span a broad energy range (0.2 keV to >15 keV). These devices will also have to be designed to withstand the harsh radiation environments associated with orbits that extend beyond the Earth's magnetosphere. This study outlines the most recent work carried out at the University of Leicester focused on improving the quantum efficiency of an X-ray sensitive CCD through direct manipulation of the device depletion region. It is also shown that increased spectral resolution is achieved using this method due to a decrease in the number of multi-pixel events. A Monte Carlo and analytical models of the CCD have been developed and used to determine the depletion depths achieved through variation of the device substrate voltage, Vss. The models are also used to investigate multi-pixel event distributions and quantum efficiency as a function of depletion depth.

  19. The Research on the Spectral Characteristics of Sea Fog Based on Caliop and Modis Data

    Science.gov (United States)

    Wan, J.; Su, J.; Liu, S.; Sheng, H.

    2018-04-01

    In view of that difficulty of distinguish between sea fog and low cloud by optical remote sensing mean, the research on spectral characteristics of sea fog is focused and carried out. The satellite laser radar CALIOP data and the high spectral MODIS data were obtained from May to December 2017, and the scattering coefficient and the vertical height information were extracted from the atmospheric attenuation of the lower star to extract the sea fog sample points, and the spectral response curve based on MODIS was formed to analyse the spectral response characteristics of the sea fog, thus providing a theoretical basis for the monitoring of sea fog with optical remote sensing image.

  20. Estimating Leaf Area Index for an arid region using Spectral Data ...

    African Journals Online (AJOL)

    In this study, spectral reflectance of pearl millet was computed at various wavelengths and at different times during the cropping season, using a spectroradiometer. Three main indices (Normalised Difference Vegetation Index, Ratio Vegetation Index, and Perpendicular Vegetation Index)were derived from the spectral data.

  1. A Study of Spectral Integration and Normalization in NMR-based Metabonomic Analyses

    Energy Technology Data Exchange (ETDEWEB)

    Webb-Robertson, Bobbie-Jo M.; Lowry, David F.; Jarman, Kristin H.; Harbo, Sam J.; Meng, Quanxin; Fuciarelli, Alfred F.; Pounds, Joel G.; Lee, Monica T.

    2005-09-15

    Metabonomics involves the quantitation of the dynamic multivariate metabolic response of an organism to a pathological event or genetic modification (Nicholson, Lindon and Holmes, 1999). The analysis of these data involves the use of appropriate multivariate statistical methods. Exploratory Data Analysis (EDA) linear projection methods, primarily Principal Component Analysis (PCA), have been documented as a valuable pattern recognition technique for 1H NMR spectral data (Brindle et al., 2002, Potts et al., 2001, Robertson et al., 2000, Robosky et al., 2002). Prior to PCA the raw data is typically processed through four steps; (1) baseline correction, (2) endogenous peak removal, (3) integration over spectral regions to reduce the number of variables, and (4) normalization. The effect of the size of spectral integration regions and normalization has not been well studied. We assess the variability structure and classification accuracy on two distinctly different datasets via PCA and a leave-one-out cross-validation approach under two normalization approaches and an array of spectral integration regions. This study indicates that independent of the normalization method the classification accuracy achieved from metabonomic studies is not highly sensitive to the size of the spectral integration region. Additionally, both datasets scaled to mean zero and unity variance (auto-scaled) has higher variability within classification accuracy over spectral integration window widths than data scaled to the total intensity of the spectrum.

  2. Gamelan Music Onset Detection based on Spectral Features

    Directory of Open Access Journals (Sweden)

    Yoyon Kusnendar Suprapto

    2013-03-01

    Full Text Available This research detects onsets of percussive instruments by examining the performance on the sound signals of gamelan instruments as one of traditional music instruments in Indonesia. Onset plays important role in determining musical rythmic structure, like beat, tempo, and is highly required in many applications of music information retrieval. There are four onset detection methods compared that employ spectral features, such as magnitude, phase, and the combination of both, which are phase slope (PS, weighted phase deviation (WPD, spectral flux (SF, and rectified complex domain (RCD. These features are extracted by representing the sound signals into time-frequency domain using overlapped Short-time Fourier Transform (STFT and varying the window length. Onset detection functions are processed through peak-picking using dynamic threshold. The results showed that by using suitable window length and parameter setting of dynamic threshold, F-measure which is greater than 0.80 can be obtained for certain methods.

  3. Camouflaged target detection based on polarized spectral features

    Science.gov (United States)

    Tan, Jian; Zhang, Junping; Zou, Bin

    2016-05-01

    The polarized hyperspectral images (PHSI) include polarization, spectral, spatial and radiant features, which provide more information about objects and scenes than traditional intensity or spectrum ones. And polarization can suppress the background and highlight the object, leading to the high potential to improve camouflaged target detection. So polarized hyperspectral imaging technique has aroused extensive concern in the last few years. Nowadays, the detection methods are still not very mature, most of which are rooted in the detection of hyperspectral image. And before using these algorithms, Stokes vector is used to process the original four-dimensional polarized hyperspectral data firstly. However, when the data is large and complex, the amount of calculation and error will increase. In this paper, tensor is applied to reconstruct the original four-dimensional data into new three-dimensional data, then, the constraint energy minimization (CEM) is used to process the new data, which adds the polarization information to construct the polarized spectral filter operator and takes full advantages of spectral and polarized information. This way deals with the original data without extracting the Stokes vector, so as to reduce the computation and error greatly. The experimental results also show that the proposed method in this paper is more suitable for the target detection of the PHSI.

  4. Spectrally adjustable quasi-monochromatic radiance source based on LEDs and its application for measuring spectral responsivity of a luminance meter

    International Nuclear Information System (INIS)

    Hirvonen, Juha-Matti; Poikonen, Tuomas; Vaskuri, Anna; Kärhä, Petri; Ikonen, Erkki

    2013-01-01

    A spectrally adjustable radiance source based on light-emitting diodes (LEDs) has been constructed for spectral responsivity measurements of radiance and luminance meters. A 300 mm integrating sphere source with adjustable output port is illuminated using 30 thermally stabilized narrow-band LEDs covering the visible wavelength range of 380–780 nm. The functionality of the measurement setup is demonstrated by measuring the relative spectral responsivities of a luminance meter and a photometer head with cosine-corrected input optics. (paper)

  5. Spectral-spatial classification of hyperspectral data with mutual information based segmented stacked autoencoder approach

    Science.gov (United States)

    Paul, Subir; Nagesh Kumar, D.

    2018-04-01

    Hyperspectral (HS) data comprises of continuous spectral responses of hundreds of narrow spectral bands with very fine spectral resolution or bandwidth, which offer feature identification and classification with high accuracy. In the present study, Mutual Information (MI) based Segmented Stacked Autoencoder (S-SAE) approach for spectral-spatial classification of the HS data is proposed to reduce the complexity and computational time compared to Stacked Autoencoder (SAE) based feature extraction. A non-parametric dependency measure (MI) based spectral segmentation is proposed instead of linear and parametric dependency measure to take care of both linear and nonlinear inter-band dependency for spectral segmentation of the HS bands. Then morphological profiles are created corresponding to segmented spectral features to assimilate the spatial information in the spectral-spatial classification approach. Two non-parametric classifiers, Support Vector Machine (SVM) with Gaussian kernel and Random Forest (RF) are used for classification of the three most popularly used HS datasets. Results of the numerical experiments carried out in this study have shown that SVM with a Gaussian kernel is providing better results for the Pavia University and Botswana datasets whereas RF is performing better for Indian Pines dataset. The experiments performed with the proposed methodology provide encouraging results compared to numerous existing approaches.

  6. Spectral network based on component cells under the SOPHIA European project

    Energy Technology Data Exchange (ETDEWEB)

    Núñez, Rubén, E-mail: ruben.nunez@ies-def.upm.es; Antón, Ignacio; Askins, Steve; Sala, Gabriel [Instituto de Energía Solar - Universidad Politécnica de Madrid, Ciudad Universitaria, 28040 Madrid (Spain); Domínguez, César; Voarino, Philippe [CEA-INES, 50 avenue du Lac Léman, 73375 Le Bourget-du-Lac (France); Steiner, Marc; Siefer, Gerald [Fraunhofer ISE, Heidenhofstr. 2, 79110 Freiburg (Germany); Fucci, Rafaelle; Roca, Franco [ENEA, P.le E.Fermi 1, Località Granatello, 80055 Portici (Italy); Minuto, Alessandro; Morabito, Paolo [RSE, Via Rubattino 54, 20134 Milan (Italy)

    2015-09-28

    In the frame of the European project SOPHIA, a spectral network based on component (also called isotypes) cells has been created. Among the members of this project, several spectral sensors based on component cells and collimating tubes, so-called spectroheliometers, were installed in the last years, allowing the collection of minute-resolution spectral data useful for CPV systems characterization across Europe. The use of spectroheliometers has been proved useful to establish the necessary spectral conditions to perform power rating of CPV modules and systems. If enough data in a given period of time is collected, ideally a year, it is possible to characterize spectrally the place where measurements are taken, in the same way that hours of annual irradiation can be estimated using a pyrheliometer.

  7. Determination of space charge region width and diffusion length in Cu(In,Ga)(S,Se)2 absorber from solar cell spectral characteristic

    International Nuclear Information System (INIS)

    Tivanov, M.; Mazanik, A.; Drozdov, N.; Zaretskaya, E.

    2010-01-01

    Full text : The space-charge region width and diffusion length of minority charge carriers in the base region (Cu(In,Ga)(S,Se) 2 absorber) are the most important parameters of the solar cell. These parameters determine the efficiency of a solar cell therefore the problem of their control is essential. In this work it is present simple non-destructive method of extracting the parameters of Cu(In,Ga)(S,Se) 2 -based solar cell (space-charge region width and diffusion length of minority charge carriers in Cu(In,Ga)(S,Se) 2 absorber) from the analysis of solar cell spectral photoresponse. The method is based on one-dimensional model of a solar cell and on the change of in-depth distribution of the photogenerated carriers in the solar cell and, hence, on the change of its photoresponse with the wave-length variation. The following assumptions are accepted: the reflection of charge carriers from a back contact and the ''drawing'' field in the quasi-neutral area of the absorber layers are absent, window and buffer layers are transparent in the analyzed part of photoresponse spectrum, the injection level of minority charge carriers is low, the recombination losses at the metallurgical p-n-junction interface of the studied photosensitive structure linearly depend on the photocurrent density. For the calculation it is necessary to obtain the following set of the experimental data: the spectral density of incident radiation, the spectral dependence of photocurrent or photovoltage of the studied photosensitive structure, the spectral dependences of optical absorption coefficient and reflectance.

  8. Approximated Function Based Spectral Gradient Algorithm for Sparse Signal Recovery

    Directory of Open Access Journals (Sweden)

    Weifeng Wang

    2014-02-01

    Full Text Available Numerical algorithms for the l0-norm regularized non-smooth non-convex minimization problems have recently became a topic of great interest within signal processing, compressive sensing, statistics, and machine learning. Nevertheless, the l0-norm makes the problem combinatorial and generally computationally intractable. In this paper, we construct a new surrogate function to approximate l0-norm regularization, and subsequently make the discrete optimization problem continuous and smooth. Then we use the well-known spectral gradient algorithm to solve the resulting smooth optimization problem. Experiments are provided which illustrate this method is very promising.

  9. Overlapping communities detection based on spectral analysis of line graphs

    Science.gov (United States)

    Gui, Chun; Zhang, Ruisheng; Hu, Rongjing; Huang, Guoming; Wei, Jiaxuan

    2018-05-01

    Community in networks are often overlapping where one vertex belongs to several clusters. Meanwhile, many networks show hierarchical structure such that community is recursively grouped into hierarchical organization. In order to obtain overlapping communities from a global hierarchy of vertices, a new algorithm (named SAoLG) is proposed to build the hierarchical organization along with detecting the overlap of community structure. SAoLG applies the spectral analysis into line graphs to unify the overlap and hierarchical structure of the communities. In order to avoid the limitation of absolute distance such as Euclidean distance, SAoLG employs Angular distance to compute the similarity between vertices. Furthermore, we make a micro-improvement partition density to evaluate the quality of community structure and use it to obtain the more reasonable and sensible community numbers. The proposed SAoLG algorithm achieves a balance between overlap and hierarchy by applying spectral analysis to edge community detection. The experimental results on one standard network and six real-world networks show that the SAoLG algorithm achieves higher modularity and reasonable community number values than those generated by Ahn's algorithm, the classical CPM and GN ones.

  10. EIT Imaging Regularization Based on Spectral Graph Wavelets.

    Science.gov (United States)

    Gong, Bo; Schullcke, Benjamin; Krueger-Ziolek, Sabine; Vauhkonen, Marko; Wolf, Gerhard; Mueller-Lisse, Ullrich; Moeller, Knut

    2017-09-01

    The objective of electrical impedance tomographic reconstruction is to identify the distribution of tissue conductivity from electrical boundary conditions. This is an ill-posed inverse problem usually solved under the finite-element method framework. In previous studies, standard sparse regularization was used for difference electrical impedance tomography to achieve a sparse solution. However, regarding elementwise sparsity, standard sparse regularization interferes with the smoothness of conductivity distribution between neighboring elements and is sensitive to noise. As an effect, the reconstructed images are spiky and depict a lack of smoothness. Such unexpected artifacts are not realistic and may lead to misinterpretation in clinical applications. To eliminate such artifacts, we present a novel sparse regularization method that uses spectral graph wavelet transforms. Single-scale or multiscale graph wavelet transforms are employed to introduce local smoothness on different scales into the reconstructed images. The proposed approach relies on viewing finite-element meshes as undirected graphs and applying wavelet transforms derived from spectral graph theory. Reconstruction results from simulations, a phantom experiment, and patient data suggest that our algorithm is more robust to noise and produces more reliable images.

  11. Spectrally-Tunable Infrared Camera Based on Highly-Sensitive Quantum Well Infrared Photodetectors, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to develop a SPECTRALLY-TUNABLE INFRARED CAMERA based on quantum well infrared photodetector (QWIP) focal plane array (FPA) technology. This will build on...

  12. Spectral Analysis of the Background in Ground-based, Long-slit ...

    Indian Academy of Sciences (India)

    1996-12-08

    Dec 8, 1996 ... Spectral Analysis of the Background in Ground-based,. Long-slit .... Figure 1 plots spectra from the 2-D array, after instrumental calibration and before correction for ..... which would merit attention and a better understanding.

  13. An integrated approach to fingerprint indexing using spectral clustering based on minutiae points

    CSIR Research Space (South Africa)

    Mngenge, NA

    2015-07-01

    Full Text Available this problem by constructing a rotational, scale and translation (RST) invariant fingerprint descriptor based on minutiae points. The proposed RST invariant descriptor dimensions are then reduced and passed to a spectral clustering algorithm which automatically...

  14. Simulative Investigation on Spectral Efficiency of Unipolar Codes based OCDMA System using Importance Sampling Technique

    Science.gov (United States)

    Farhat, A.; Menif, M.; Rezig, H.

    2013-09-01

    This paper analyses the spectral efficiency of Optical Code Division Multiple Access (OCDMA) system using Importance Sampling (IS) technique. We consider three configurations of OCDMA system namely Direct Sequence (DS), Spectral Amplitude Coding (SAC) and Fast Frequency Hopping (FFH) that exploits the Fiber Bragg Gratings (FBG) based encoder/decoder. We evaluate the spectral efficiency of the considered system by taking into consideration the effect of different families of unipolar codes for both coherent and incoherent sources. The results show that the spectral efficiency of OCDMA system with coherent source is higher than the incoherent case. We demonstrate also that DS-OCDMA outperforms both others in terms of spectral efficiency in all conditions.

  15. Parameters optimization for wavelet denoising based on normalized spectral angle and threshold constraint machine learning

    Science.gov (United States)

    Li, Hao; Ma, Yong; Liang, Kun; Tian, Yong; Wang, Rui

    2012-01-01

    Wavelet parameters (e.g., wavelet type, level of decomposition) affect the performance of the wavelet denoising algorithm in hyperspectral applications. Current studies select the best wavelet parameters for a single spectral curve by comparing similarity criteria such as spectral angle (SA). However, the method to find the best parameters for a spectral library that contains multiple spectra has not been studied. In this paper, a criterion named normalized spectral angle (NSA) is proposed. By comparing NSA, the best combination of parameters for a spectral library can be selected. Moreover, a fast algorithm based on threshold constraint and machine learning is developed to reduce the time of a full search. After several iterations of learning, the combination of parameters that constantly surpasses a threshold is selected. The experiments proved that by using the NSA criterion, the SA values decreased significantly, and the fast algorithm could save 80% time consumption, while the denoising performance was not obviously impaired.

  16. M101: Spectral Observations of H II Regions and Their Physical Properties

    Science.gov (United States)

    Hu, Ning; Wang, Enci; Lin, Zesen; Kong, Xu; Cheng, Fuzhen; Fan, Zou; Fang, Guangwen; Lin, Lin; Mao, Yewei; Wang, Jing; Zhou, Xu; Zhou, Zhiming; Zhu, Yinan; Zou, Hu

    2018-02-01

    By using the Hectospec 6.5 m Multiple Mirror Telescope and the 2.16 m telescope of the National Astronomical Observatories, of the Chinese Academy of Sciences, we obtained 188 high signal-to-noise ratio spectra of {{H}} {{II}} regions in the nearby galaxy M101, which is the largest spectroscopic sample of {{H}} {{II}} regions for this galaxy so far. These spectra cover a wide range of regions on M101, which enables us to analyze two-dimensional distributions of its physical properties. The physical parameters are derived from emission lines or stellar continua, including stellar population age, electron temperature, oxygen abundance, etc. The oxygen abundances are derived using two empirical methods based on O3N2 and R 23 indicators, as well as the direct {T}e method when [{{O}} {{III}}] λ 4363 is available. By applying the harmonic decomposition analysis to the velocity field, we obtained a line-of-sight rotation velocity of 71 {km} {{{s}}}-1 and a position angle of 36°. The stellar age profile shows an old stellar population in the galaxy center and a relatively young stellar population in outer regions, suggesting an old bulge and a young disk. The oxygen abundance profile exhibits a clear break at ∼18 kpc, with a gradient of ‑0.0364 dex kpc‑1 in the inner region and ‑0.00686 dex kpc‑1 in the outer region. Our results agree with the “inside-out” disk growth scenario of M101.

  17. Local and Global Gestalt Laws: A Neurally Based Spectral Approach.

    Science.gov (United States)

    Favali, Marta; Citti, Giovanna; Sarti, Alessandro

    2017-02-01

    This letter presents a mathematical model of figure-ground articulation that takes into account both local and global gestalt laws and is compatible with the functional architecture of the primary visual cortex (V1). The local gestalt law of good continuation is described by means of suitable connectivity kernels that are derived from Lie group theory and quantitatively compared with long-range connectivity in V1. Global gestalt constraints are then introduced in terms of spectral analysis of a connectivity matrix derived from these kernels. This analysis performs grouping of local features and individuates perceptual units with the highest salience. Numerical simulations are performed, and results are obtained by applying the technique to a number of stimuli.

  18. Mineralogy and Iron Content of the Lunar Polar Regions Using the Kaguya Spectral Profiler and the Lunar Orbiter Laser Altimeter

    Science.gov (United States)

    Lemelin, M.; Lucey, P. G.; Trang, D.; Jha, K.

    2016-12-01

    The lunar polar regions are of high scientific interest, but the extreme lighting conditions have made quantitative analyses using reflectance spectra difficult; some regions are in permanent shadow, and flat surfaces are difficult to correct photometrically due to the extreme grazing incidence and low signal available. Thus, most mineral maps derived from visible and near infrared reflectance spectra have been constrained to within 50° in latitude. The mineralogy of the polar regions, or 44% of the lunar surface, is almost entirely unknown. A few studies have provided compositional analysis based on the spectral shape (where strong absorption bands were present) of lithologies dominated by one or two minerals. In this study, we take a novel approach and use strong signal and well-calibrated reflectance acquired by two different instruments, the Kaguya Spectra Profiler (SP) and the Lunar Orbiter Laser Altimeter (LOLA), in order to derive the first FeO and mineral maps of the polar regions at a spatial resolution of 1 km per pixel. We use reflectance ratios from SP and calibrated reflectance data from LOLA to derive the first polar maps of FeO, which are within 2 wt.% of the FeO measured by the Lunar Prospector Gamma-Ray spectrometer up to 85° in latitude. We then use the reflectance data from SP and Hapke radiative transfer model to compute the abundance of olivine, low-calcium pyroxene, high-calcium pyroxene and plagioclase, using FeO as a constraint. The radiative transfer model yields an error in mineral abundances of 9 wt.%. We use the mineral maps to study the composition of 27 central peaks and 5 basin rings in the polar regions, and relate their composition to their depth of origin in the lunar crust. We find that the central peaks and basin rings in Feldspathic Highlands Terrane are mostly anorthositic in composition, with modal plagioclase content ranging between 66 and 92 wt.%. The central peaks and basin rings in the South Pole-Aitken basin are noritic

  19. Investigation on atmospheric transmittance based on spectral and total direct insolation data; Nissha data ni motozuku taiki tokaritsu no kento

    Energy Technology Data Exchange (ETDEWEB)

    Baba, H; Kanayama, K; Endo, N [Kitami Institute of Technology, Hokkaido (Japan)

    1997-11-25

    Spectral insolation values measured at Kitami since 1994 by using a multi-purpose spectral radiometer, and direct insolation data collected at seven locations are available. Based on these data, effects of sun`s altitude and atmospheric condition on atmospheric transmittance were discussed. Spectra of insolation received on the ground are subjected to scattering and absorption by gas and particulates, and show complex shapes while they transmit from the sun, reach the atmosphere of the earth and pass through the atmosphere. The Bird`s model is shown. Impact of the sun`s altitude on the spectra of insolation directly reaching the ground is small if the altitude is higher than 45 degrees. The impact grows suddenly large when it is lower than 30 degrees. Atmospheric turbidity (caused by aerosols generated by volcanic eruption or exhaust gases) affects the spectral transmittance over the whole wavelength region. Amount of steam in the atmosphere has a strong effect on the spectral transmittance in the steam absorption band. Total transmittance of the atmosphere was sought based on the measurement data of insolation directly reaching the ground at eight locations from Kitami to Shiono-misaki. The transmittance at each location is in a range from 0.75 to 0.83 showing close proximity. These data agreed well also with the average transmittance surveyed by the Meteorological Agency. 7 refs., 8 figs.

  20. Methods for Enhancing Geological Structures in Spectral Spatial Difference-Based on Remote-Sensing Image

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    @@In this paper, some image processing methods such as directional template (mask) matching enhancement, pseudocolor or false color enhancement, K-L transform enhancement are used to enhance a geological structure, one of important ore-controlling factors, shown in the remote-sensing images.This geological structure is regarded as image anomaly in the remote-sensing image, since considerable differences, based on the spatial spectral distribution pattern, in gray values (spectral), color tones and texture, are always present between the geological structure and background. Therefore,the enhancement of the geological structure in the remotesensing image is that of the spectral spatial difference.

  1. Spectral studies of new fullerene-tetrathiafulvalene based system

    International Nuclear Information System (INIS)

    Laskowska, Barbara; Lapinski, Andrzej; Graja, Andrzej; Hudhomme, Pietrick

    2007-01-01

    Molecular and electronic structures as well as electronic and vibrational spectra of compounds 1-3 were investigated. The spectra were recorded in the large spectral range from 400 to 50,000 cm -1 ; our interest was focused on the electronic excitations of both moieties of the dyad and the intramolecular vibrations of the dyad's components. With the help of the Gaussian 03 program, molecular geometry, electron structure and normal mode analysis for the dyad and/or reference compounds were studied. An assignment of the main vibrational bands of the dyad and its reference molecules was made taking into consideration their IR and Raman spectra as well as results of the normal mode analysis. In principle, the intramolecular vibrations typical for C 60 and tetrathiafulvalene (TTF) derivatives can be found in the spectra of the dyad; the bands' frequencies are insignificantly shifted comparing with the separated molecules but their shape is usually modified. It suggests that symmetry and molecular structure of both components of the dyad are rather kept after dyad's formation but redistribution of charges occurs

  2. Epileptic seizure prediction based on a bivariate spectral power methodology.

    Science.gov (United States)

    Bandarabadi, Mojtaba; Teixeira, Cesar A; Direito, Bruno; Dourado, Antonio

    2012-01-01

    The spectral power of 5 frequently considered frequency bands (Alpha, Beta, Gamma, Theta and Delta) for 6 EEG channels is computed and then all the possible pairwise combinations among the 30 features set, are used to create a 435 dimensional feature space. Two new feature selection methods are introduced to choose the best candidate features among those and to reduce the dimensionality of this feature space. The selected features are then fed to Support Vector Machines (SVMs) that classify the cerebral state in preictal and non-preictal classes. The outputs of the SVM are regularized using a method that accounts for the classification dynamics of the preictal class, also known as "Firing Power" method. The results obtained using our feature selection approaches are compared with the ones obtained using minimum Redundancy Maximum Relevance (mRMR) feature selection method. The results in a group of 12 patients of the EPILEPSIAE database, containing 46 seizures and 787 hours multichannel recording for out-of-sample data, indicate the efficiency of the bivariate approach as well as the two new feature selection methods. The best results presented sensitivity of 76.09% (35 of 46 seizures predicted) and a false prediction rate of 0.15(-1).

  3. Spectral implementation of full waveform inversion based on reflections

    KAUST Repository

    Wu, Zedong

    2014-01-01

    Using the reflection imaging process as a source to model reflections for full waveform inversion (FWI), referred to as reflection FWI (RFWI), allows us to update the background component of the model, and avoid using the relatively costly migration velocity analysis (MVA), which usually relies on extended images. However, RFWI requires a good image to represent the current reflectivity, as well as, some effort to obtain good smooth gradients. We develop a spectral implementation of RFWI where the wavefield extrapolations and gradient evaluation are performed in the wavenumber domain, obtaining clean dispersion free and fast extrapolations. The gradient, in this case, yields three terms, two of which provide us with each side of the rabbit ear kernel, and the third, often ignored, provides a normalization of the reflectivity within the kernel, which can be used to obtain a reflectivity free background update. Since the image is imperfect (it is an adjoint, not an inverse), an optimization process for the third term scaling is implemented to achieve the smoothest gradient update. A rare application of RFWI on the reflectivity infested Marmousi model shows some of the potential of the approach.

  4. [Estimation of Hunan forest carbon density based on spectral mixture analysis of MODIS data].

    Science.gov (United States)

    Yan, En-ping; Lin, Hui; Wang, Guang-xing; Chen, Zhen-xiong

    2015-11-01

    With the fast development of remote sensing technology, combining forest inventory sample plot data and remotely sensed images has become a widely used method to map forest carbon density. However, the existence of mixed pixels often impedes the improvement of forest carbon density mapping, especially when low spatial resolution images such as MODIS are used. In this study, MODIS images and national forest inventory sample plot data were used to conduct the study of estimation for forest carbon density. Linear spectral mixture analysis with and without constraint, and nonlinear spectral mixture analysis were compared to derive the fractions of different land use and land cover (LULC) types. Then sequential Gaussian co-simulation algorithm with and without the fraction images from spectral mixture analyses were employed to estimate forest carbon density of Hunan Province. Results showed that 1) Linear spectral mixture analysis with constraint, leading to a mean RMSE of 0.002, more accurately estimated the fractions of LULC types than linear spectral and nonlinear spectral mixture analyses; 2) Integrating spectral mixture analysis model and sequential Gaussian co-simulation algorithm increased the estimation accuracy of forest carbon density to 81.5% from 74.1%, and decreased the RMSE to 5.18 from 7.26; and 3) The mean value of forest carbon density for the province was 30.06 t · hm(-2), ranging from 0.00 to 67.35 t · hm(-2). This implied that the spectral mixture analysis provided a great potential to increase the estimation accuracy of forest carbon density on regional and global level.

  5. A Spectral-Texture Kernel-Based Classification Method for Hyperspectral Images

    Directory of Open Access Journals (Sweden)

    Yi Wang

    2016-11-01

    Full Text Available Classification of hyperspectral images always suffers from high dimensionality and very limited labeled samples. Recently, the spectral-spatial classification has attracted considerable attention and can achieve higher classification accuracy and smoother classification maps. In this paper, a novel spectral-spatial classification method for hyperspectral images by using kernel methods is investigated. For a given hyperspectral image, the principle component analysis (PCA transform is first performed. Then, the first principle component of the input image is segmented into non-overlapping homogeneous regions by using the entropy rate superpixel (ERS algorithm. Next, the local spectral histogram model is applied to each homogeneous region to obtain the corresponding texture features. Because this step is performed within each homogenous region, instead of within a fixed-size image window, the obtained local texture features in the image are more accurate, which can effectively benefit the improvement of classification accuracy. In the following step, a contextual spectral-texture kernel is constructed by combining spectral information in the image and the extracted texture information using the linearity property of the kernel methods. Finally, the classification map is achieved by the support vector machines (SVM classifier using the proposed spectral-texture kernel. Experiments on two benchmark airborne hyperspectral datasets demonstrate that our method can effectively improve classification accuracies, even though only a very limited training sample is available. Specifically, our method can achieve from 8.26% to 15.1% higher in terms of overall accuracy than the traditional SVM classifier. The performance of our method was further compared to several state-of-the-art classification methods of hyperspectral images using objective quantitative measures and a visual qualitative evaluation.

  6. THE RESEARCH ON THE SPECTRAL CHARACTERISTICS OF SEA FOG BASED ON CALIOP AND MODIS DATA

    Directory of Open Access Journals (Sweden)

    J. Wan

    2018-04-01

    Full Text Available In view of that difficulty of distinguish between sea fog and low cloud by optical remote sensing mean, the research on spectral characteristics of sea fog is focused and carried out。The satellite laser radar CALIOP data and the high spectral MODIS data were obtained from May to December 2017, and the scattering coefficient and the vertical height information were extracted from the atmospheric attenuation of the lower star to extract the sea fog sample points, and the spectral response curve based on MODIS was formed to analyse the spectral response characteristics of the sea fog, thus providing a theoretical basis for the monitoring of sea fog with optical remote sensing image.

  7. Self-training-based spectral image reconstruction for art paintings with multispectral imaging.

    Science.gov (United States)

    Xu, Peng; Xu, Haisong; Diao, Changyu; Ye, Zhengnan

    2017-10-20

    A self-training-based spectral reflectance recovery method was developed to accurately reconstruct the spectral images of art paintings with multispectral imaging. By partitioning the multispectral images with the k-means clustering algorithm, the training samples are directly extracted from the art painting itself to restrain the deterioration of spectral estimation caused by the material inconsistency between the training samples and the art painting. Coordinate paper is used to locate the extracted training samples. The spectral reflectances of the extracted training samples are acquired indirectly with a spectroradiometer, and the circle Hough transform is adopted to detect the circle measuring area of the spectroradiometer. Through simulation and a practical experiment, the implementation of the proposed method is explained in detail, and it is verified to have better reflectance recovery performance than that using the commercial target and is comparable to the approach using a painted color target.

  8. A reflectivity profilometer for the optical characterisation of graded reflectivity mirrors in the 250 nm - 1100 nm spectral region

    International Nuclear Information System (INIS)

    Colucci, Alessandro; Nichelatti, Enrico

    1998-04-01

    It's developed the prototype of an instrument that can be used for the optical characterisation of graded reflectivity mirrors at any wavelength in the spectral region from 250 nm to 1100 nm. The instrument utilises a high-pressure Xe arc lamp as light source. Light is spectrally filtered by means of a grating monochromator. The sample is illuminated with an image of the monochromator exit slit. After reflection from the sample, this image is projected onto a 1024-elements charge-coupled device linear array driven by a digital frame board and interfaced with a personal computer. It's tested the instrument accuracy by comparing measurement results with the corresponding ones obtained by means of a laser scanning technique. Measurement Rms repeatability has been estimated to be approximately of 0.8% [it

  9. A Spectral Reconstruction Algorithm of Miniature Spectrometer Based on Sparse Optimization and Dictionary Learning.

    Science.gov (United States)

    Zhang, Shang; Dong, Yuhan; Fu, Hongyan; Huang, Shao-Lun; Zhang, Lin

    2018-02-22

    The miniaturization of spectrometer can broaden the application area of spectrometry, which has huge academic and industrial value. Among various miniaturization approaches, filter-based miniaturization is a promising implementation by utilizing broadband filters with distinct transmission functions. Mathematically, filter-based spectral reconstruction can be modeled as solving a system of linear equations. In this paper, we propose an algorithm of spectral reconstruction based on sparse optimization and dictionary learning. To verify the feasibility of the reconstruction algorithm, we design and implement a simple prototype of a filter-based miniature spectrometer. The experimental results demonstrate that sparse optimization is well applicable to spectral reconstruction whether the spectra are directly sparse or not. As for the non-directly sparse spectra, their sparsity can be enhanced by dictionary learning. In conclusion, the proposed approach has a bright application prospect in fabricating a practical miniature spectrometer.

  10. A Spectral Reconstruction Algorithm of Miniature Spectrometer Based on Sparse Optimization and Dictionary Learning

    Science.gov (United States)

    Zhang, Shang; Fu, Hongyan; Huang, Shao-Lun; Zhang, Lin

    2018-01-01

    The miniaturization of spectrometer can broaden the application area of spectrometry, which has huge academic and industrial value. Among various miniaturization approaches, filter-based miniaturization is a promising implementation by utilizing broadband filters with distinct transmission functions. Mathematically, filter-based spectral reconstruction can be modeled as solving a system of linear equations. In this paper, we propose an algorithm of spectral reconstruction based on sparse optimization and dictionary learning. To verify the feasibility of the reconstruction algorithm, we design and implement a simple prototype of a filter-based miniature spectrometer. The experimental results demonstrate that sparse optimization is well applicable to spectral reconstruction whether the spectra are directly sparse or not. As for the non-directly sparse spectra, their sparsity can be enhanced by dictionary learning. In conclusion, the proposed approach has a bright application prospect in fabricating a practical miniature spectrometer. PMID:29470406

  11. A novel and compact spectral imaging system based on two curved prisms

    Science.gov (United States)

    Nie, Yunfeng; Bin, Xiangli; Zhou, Jinsong; Li, Yang

    2013-09-01

    As a novel detection approach which simultaneously acquires two-dimensional visual picture and one-dimensional spectral information, spectral imaging offers promising applications on biomedical imaging, conservation and identification of artworks, surveillance of food safety, and so forth. A novel moderate-resolution spectral imaging system consisting of merely two optical elements is illustrated in this paper. It can realize the function of a relay imaging system as well as a 10nm spectral resolution spectroscopy. Compared to conventional prismatic imaging spectrometers, this design is compact and concise with only two special curved prisms by utilizing two reflective surfaces. In contrast to spectral imagers based on diffractive grating, the usage of compound-prism possesses characteristics of higher energy utilization and wider free spectral range. The seidel aberration theory and dispersive principle of this special prism are analyzed at first. According to the results, the optical system of this design is simulated, and the performance evaluation including spot diagram, MTF and distortion, is presented. In the end, considering the difficulty and particularity of manufacture and alignment, an available method for fabrication and measurement is proposed.

  12. Dimensionality Reduction of Hyperspectral Image with Graph-Based Discriminant Analysis Considering Spectral Similarity

    Directory of Open Access Journals (Sweden)

    Fubiao Feng

    2017-03-01

    Full Text Available Recently, graph embedding has drawn great attention for dimensionality reduction in hyperspectral imagery. For example, locality preserving projection (LPP utilizes typical Euclidean distance in a heat kernel to create an affinity matrix and projects the high-dimensional data into a lower-dimensional space. However, the Euclidean distance is not sufficiently correlated with intrinsic spectral variation of a material, which may result in inappropriate graph representation. In this work, a graph-based discriminant analysis with spectral similarity (denoted as GDA-SS measurement is proposed, which fully considers curves changing description among spectral bands. Experimental results based on real hyperspectral images demonstrate that the proposed method is superior to traditional methods, such as supervised LPP, and the state-of-the-art sparse graph-based discriminant analysis (SGDA.

  13. Optical microwave filter based on spectral slicing by use of arrayed waveguide gratings.

    Science.gov (United States)

    Pastor, Daniel; Ortega, Beatriz; Capmany, José; Sales, Salvador; Martinez, Alfonso; Muñoz, Pascual

    2003-10-01

    We have experimentally demonstrated a new optical signal processor based on the use of arrayed waveguide gratings. The structure exploits the concept of spectral slicing combined with the use of an optical dispersive medium. The approach presents increased flexibility from previous slicing-based structures in terms of tunability, reconfiguration, and apodization of the samples or coefficients of the transversal optical filter.

  14. Multi-spectral band selection for satellite-based systems

    International Nuclear Information System (INIS)

    Clodius, W.B.; Weber, P.G.; Borel, C.C.; Smith, B.W.

    1998-01-01

    The design of satellite based multispectral imaging systems requires the consideration of a number of tradeoffs between cost and performance. The authors have recently been involved in the design and evaluation of a satellite based multispectral sensor operating from the visible through the long wavelength IR. The criteria that led to some of the proposed designs and the modeling used to evaluate and fine tune the designs will both be discussed. These criteria emphasized the use of bands for surface temperature retrieval and the correction of atmospheric effects. The impact of cost estimate changes on the final design will also be discussed

  15. A Statistical study of the Doppler spectral width of high-latitude ionospheric F-region echoes recorded with SuperDARN coherent HF radars

    Directory of Open Access Journals (Sweden)

    J.-P. Villain

    2002-11-01

    Full Text Available The HF radars of the Super Dual Auroral Radar Network (SuperDARN provide measurements of the E × B drift of ionospheric plasma over extended regions of the high-latitude ionosphere. We have conducted a statistical study of the associated Doppler spectral width of ionospheric F-region echoes. The study has been conducted with all available radars from the Northern Hemisphere for 2 specific periods of time. Period 1 corresponds to the winter months of 1994, while period 2 covers October 1996 to March 1997. The distributions of data points and average spectral width are presented as a function of Magnetic Latitude and Magnetic Local Time. The databases are very consistent and exhibit the same features. The most stringent features are: a region of very high spectral width, collocated with the ionospheric LLBL/cusp/mantle region; an oval shaped region of high spectral width, whose equator-ward boundary matches the poleward limit of the Holzworth and Meng auroral oval. A simulation has been conducted to evaluate the geometrical and instrumental effects on the spectral width. It shows that these effects cannot account for the observed spectral features. It is then concluded that these specific spectral width characteristics are the signature of ionospheric/magnetospheric coupling phenomena.Key words. Ionosphere (auroral ionosphere; ionosphere-magnetosphere interactions; ionospheric irregularities

  16. A Statistical study of the Doppler spectral width of high-latitude ionospheric F-region echoes recorded with SuperDARN coherent HF radars

    Directory of Open Access Journals (Sweden)

    J.-P. Villain

    Full Text Available The HF radars of the Super Dual Auroral Radar Network (SuperDARN provide measurements of the E × B drift of ionospheric plasma over extended regions of the high-latitude ionosphere. We have conducted a statistical study of the associated Doppler spectral width of ionospheric F-region echoes. The study has been conducted with all available radars from the Northern Hemisphere for 2 specific periods of time. Period 1 corresponds to the winter months of 1994, while period 2 covers October 1996 to March 1997. The distributions of data points and average spectral width are presented as a function of Magnetic Latitude and Magnetic Local Time. The databases are very consistent and exhibit the same features. The most stringent features are: a region of very high spectral width, collocated with the ionospheric LLBL/cusp/mantle region; an oval shaped region of high spectral width, whose equator-ward boundary matches the poleward limit of the Holzworth and Meng auroral oval. A simulation has been conducted to evaluate the geometrical and instrumental effects on the spectral width. It shows that these effects cannot account for the observed spectral features. It is then concluded that these specific spectral width characteristics are the signature of ionospheric/magnetospheric coupling phenomena.

    Key words. Ionosphere (auroral ionosphere; ionosphere-magnetosphere interactions; ionospheric irregularities

  17. Temporal behavior of unresolved transition array emission in water window soft x-ray spectral region from multiply charged ions

    Energy Technology Data Exchange (ETDEWEB)

    Dinh, Thanh-Hung, E-mail: dinh@cc.utsunomiya-u.ac.jp; Suzuki, Yuhei; Arai, Goki; Higashiguchi, Takeshi, E-mail: higashi@cc.utsunomiya-u.ac.jp [Department of Electrical and Electronic Engineering, Faculty of Engineering and Center for Optical Research and Education (CORE), Utsunomiya University, Yoto 7-1-2, Utsunomiya, Tochigi 321-8585 (Japan); Li, Bowen [School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000 (China); Dunne, Padraig; O' Sullivan, Gerry [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland); Fujioka, Shinsuke [Institute of Laser Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0871 (Japan); Hasegawa, Noboru; Kawachi, Tetsuya; Nishikino, Masaharu [Quantum Beam Science Center, Japan Atomic Energy Agency, 8-1-7 Umemidai, Kizugawa, Kyoto 619-0215 (Japan)

    2015-09-21

    We have characterized the spectral structure and the temporal history of the laser-produced high-Z multi-charged ion plasmas for the efficient water window soft x-ray sources. Strong unresolved transition array emission was observed due to 4d–4f and 4f–5g transitions from Au, Pb, and Bi plasmas in the 280–700 eV photon energy region. The temporal behavior of the emission was essentially similar of that of the laser pulse with a slight delay between different transitions. These results provide feedback for accurate modeling of the atomic processes with the radiative hydrodynamic simulations.

  18. Electroluminescence from a single InGaN quantum dot in the green spectral region up to 150 K

    International Nuclear Information System (INIS)

    Kalden, J; Sebald, K; Gutowski, J; Tessarek, C; Figge, S; Kruse, C; Hommel, D

    2010-01-01

    We present electrically driven luminescence from single InGaN quantum dots embedded into a light emitting diode structure grown by metal-organic vapor-phase epitaxy. Single sharp emission lines in the green spectral region can be identified. Temperature dependent measurements demonstrate thermal stability of the emission of a single quantum dot up to 150 K. These results are an important step towards applications like electrically driven single-photon emitters, which are a basis for applications incorporating plastic optical fibers as well as for modern concepts of free space quantum cryptography.

  19. Path connectivity based spectral defragmentation in flexible bandwidth networks.

    Science.gov (United States)

    Wang, Ying; Zhang, Jie; Zhao, Yongli; Zhang, Jiawei; Zhao, Jie; Wang, Xinbo; Gu, Wanyi

    2013-01-28

    Optical networks with flexible bandwidth provisioning have become a very promising networking architecture. It enables efficient resource utilization and supports heterogeneous bandwidth demands. In this paper, two novel spectrum defragmentation approaches, i.e. Maximum Path Connectivity (MPC) algorithm and Path Connectivity Triggering (PCT) algorithm, are proposed based on the notion of Path Connectivity, which is defined to represent the maximum variation of node switching ability along the path in flexible bandwidth networks. A cost-performance-ratio based profitability model is given to denote the prons and cons of spectrum defragmentation. We compare these two proposed algorithms with non-defragmentation algorithm in terms of blocking probability. Then we analyze the differences of defragmentation profitability between MPC and PCT algorithms.

  20. OTDM-WDM Conversion Based on Time-Domain Optical Fourier Transformation with Spectral Compression

    DEFF Research Database (Denmark)

    Mulvad, Hans Christian Hansen; Palushani, Evarist; Galili, Michael

    2011-01-01

    We propose a scheme enabling direct serial-to-parallel conversion of OTDM data tributaries onto a WDM grid, based on optical Fourier transformation with spectral compression. Demonstrations on 320 Gbit/s and 640 Gbit/s OTDM data are shown.......We propose a scheme enabling direct serial-to-parallel conversion of OTDM data tributaries onto a WDM grid, based on optical Fourier transformation with spectral compression. Demonstrations on 320 Gbit/s and 640 Gbit/s OTDM data are shown....

  1. Spectral-based features ranking for gamelan instruments identification using filter techniques

    Directory of Open Access Journals (Sweden)

    Diah P Wulandari

    2013-03-01

    Full Text Available In this paper, we describe an approach of spectral-based features ranking for Javanese gamelaninstruments identification using filter techniques. The model extracted spectral-based features set of thesignal using Short Time Fourier Transform (STFT. The rank of the features was determined using the fivealgorithms; namely ReliefF, Chi-Squared, Information Gain, Gain Ratio, and Symmetric Uncertainty. Then,we tested the ranked features by cross validation using Support Vector Machine (SVM. The experimentshowed that Gain Ratio algorithm gave the best result, it yielded accuracy of 98.93%.

  2. Automics: an integrated platform for NMR-based metabonomics spectral processing and data analysis

    Directory of Open Access Journals (Sweden)

    Qu Lijia

    2009-03-01

    Full Text Available Abstract Background Spectral processing and post-experimental data analysis are the major tasks in NMR-based metabonomics studies. While there are commercial and free licensed software tools available to assist these tasks, researchers usually have to use multiple software packages for their studies because software packages generally focus on specific tasks. It would be beneficial to have a highly integrated platform, in which these tasks can be completed within one package. Moreover, with open source architecture, newly proposed algorithms or methods for spectral processing and data analysis can be implemented much more easily and accessed freely by the public. Results In this paper, we report an open source software tool, Automics, which is specifically designed for NMR-based metabonomics studies. Automics is a highly integrated platform that provides functions covering almost all the stages of NMR-based metabonomics studies. Automics provides high throughput automatic modules with most recently proposed algorithms and powerful manual modules for 1D NMR spectral processing. In addition to spectral processing functions, powerful features for data organization, data pre-processing, and data analysis have been implemented. Nine statistical methods can be applied to analyses including: feature selection (Fisher's criterion, data reduction (PCA, LDA, ULDA, unsupervised clustering (K-Mean and supervised regression and classification (PLS/PLS-DA, KNN, SIMCA, SVM. Moreover, Automics has a user-friendly graphical interface for visualizing NMR spectra and data analysis results. The functional ability of Automics is demonstrated with an analysis of a type 2 diabetes metabolic profile. Conclusion Automics facilitates high throughput 1D NMR spectral processing and high dimensional data analysis for NMR-based metabonomics applications. Using Automics, users can complete spectral processing and data analysis within one software package in most cases

  3. Automics: an integrated platform for NMR-based metabonomics spectral processing and data analysis.

    Science.gov (United States)

    Wang, Tao; Shao, Kang; Chu, Qinying; Ren, Yanfei; Mu, Yiming; Qu, Lijia; He, Jie; Jin, Changwen; Xia, Bin

    2009-03-16

    Spectral processing and post-experimental data analysis are the major tasks in NMR-based metabonomics studies. While there are commercial and free licensed software tools available to assist these tasks, researchers usually have to use multiple software packages for their studies because software packages generally focus on specific tasks. It would be beneficial to have a highly integrated platform, in which these tasks can be completed within one package. Moreover, with open source architecture, newly proposed algorithms or methods for spectral processing and data analysis can be implemented much more easily and accessed freely by the public. In this paper, we report an open source software tool, Automics, which is specifically designed for NMR-based metabonomics studies. Automics is a highly integrated platform that provides functions covering almost all the stages of NMR-based metabonomics studies. Automics provides high throughput automatic modules with most recently proposed algorithms and powerful manual modules for 1D NMR spectral processing. In addition to spectral processing functions, powerful features for data organization, data pre-processing, and data analysis have been implemented. Nine statistical methods can be applied to analyses including: feature selection (Fisher's criterion), data reduction (PCA, LDA, ULDA), unsupervised clustering (K-Mean) and supervised regression and classification (PLS/PLS-DA, KNN, SIMCA, SVM). Moreover, Automics has a user-friendly graphical interface for visualizing NMR spectra and data analysis results. The functional ability of Automics is demonstrated with an analysis of a type 2 diabetes metabolic profile. Automics facilitates high throughput 1D NMR spectral processing and high dimensional data analysis for NMR-based metabonomics applications. Using Automics, users can complete spectral processing and data analysis within one software package in most cases. Moreover, with its open source architecture, interested

  4. An improved feature extraction algorithm based on KAZE for multi-spectral image

    Science.gov (United States)

    Yang, Jianping; Li, Jun

    2018-02-01

    Multi-spectral image contains abundant spectral information, which is widely used in all fields like resource exploration, meteorological observation and modern military. Image preprocessing, such as image feature extraction and matching, is indispensable while dealing with multi-spectral remote sensing image. Although the feature matching algorithm based on linear scale such as SIFT and SURF performs strong on robustness, the local accuracy cannot be guaranteed. Therefore, this paper proposes an improved KAZE algorithm, which is based on nonlinear scale, to raise the number of feature and to enhance the matching rate by using the adjusted-cosine vector. The experiment result shows that the number of feature and the matching rate of the improved KAZE are remarkably than the original KAZE algorithm.

  5. Sandmeier model based topographic correction to lunar spectral profiler (SP) data from KAGUYA satellite.

    Science.gov (United States)

    Chen, Sheng-Bo; Wang, Jing-Ran; Guo, Peng-Ju; Wang, Ming-Chang

    2014-09-01

    The Moon may be considered as the frontier base for the deep space exploration. The spectral analysis is one of the key techniques to determine the lunar surface rock and mineral compositions. But the lunar topographic relief is more remarkable than that of the Earth. It is necessary to conduct the topographic correction for lunar spectral data before they are used to retrieve the compositions. In the present paper, a lunar Sandmeier model was proposed by considering the radiance effect from the macro and ambient topographic relief. And the reflectance correction model was also reduced based on the Sandmeier model. The Spectral Profile (SP) data from KAGUYA satellite in the Sinus Iridum quadrangle was taken as an example. And the digital elevation data from Lunar Orbiter Laser Altimeter are used to calculate the slope, aspect, incidence and emergence angles, and terrain-viewing factor for the topographic correction Thus, the lunar surface reflectance from the SP data was corrected by the proposed model after the direct component of irradiance on a horizontal surface was derived. As a result, the high spectral reflectance facing the sun is decreased and low spectral reflectance back to the sun is compensated. The statistical histogram of reflectance-corrected pixel numbers presents Gaussian distribution Therefore, the model is robust to correct lunar topographic effect and estimate lunar surface reflectance.

  6. Laboratory calibration of density-dependent lines in the extreme ultraviolet spectral region

    Science.gov (United States)

    Lepson, J. K.; Beiersdorfer, P.; Gu, M. F.; Desai, P.; Bitter, M.; Roquemore, L.; Reinke, M. L.

    2012-05-01

    We have been making spectral measurements in the extreme ultraviolet (EUV) from different laboratory sources in order to investigate the electron density dependence of various astrophysically important emission lines and to test the atomic models underlying the diagnostic line ratios. The measurement are being performed at the Livermore EBIT-I electron beam ion trap, the National Spherical Torus Experiment (NSTX) at Princeton, and the Alcator C-Mod tokamak at the Massachusetts Institute of Technology, which together span an electron density of four orders of magnitude and which allow us to test the various models at high and low density limits. Here we present measurements of Fe XXII and Ar XIV, which include new data from an ultra high resolution (λ/Δλ >4000) spectrometer at the EBIT-I facility. We found good agreement between the measurements and modeling calculations for Fe XXII, but poorer agreement for Ar XIV.

  7. Searching for I-band variability in stars in the M/L spectral transition region

    Science.gov (United States)

    Ramsay, Gavin; Hakala, Pasi; Doyle, J. Gerry

    2015-10-01

    We report on I-band photometric observations of 21 stars with spectral types between M8 and L4 made using the Isaac Newton Telescope. The total amount of time for observations which had a cadence of test for photometric variability using the Kruskal-Wallis H-test and find that four sources (2MASS J10224821+5825453, 2MASS J07464256+2000321, 2MASS J16262034+3925190 and 2MASS J12464678+4027150) were found to be significantly variable at least on one epoch. Three of these sources are reported as photometrically variable for the first time. If we include sources which were deemed marginally variable, the number of variable sources is 6 (29 per cent). No flares were detected from any source. The percentage of sources which we found were variable is similar to previous studies. We summarize the mechanisms which have been put forward to explain the light curves of brown dwarfs.

  8. Actuated polymer based dielectric mirror for visual spectral range applications

    Science.gov (United States)

    Vergara, Pedro P.; Lunardi, Leda

    2017-08-01

    Miniature dielectric mirrors are useful components for lasers, thin film beam splitters and high quality mirrors in optics. These mirrors usually made from rigid inorganic materials can achieve a reflectance of almost one hundred percent. Being structural components, as soon as fabricated their reflectance and/or bandwidth remains constant. Here it is presented a novel fabrication process of a dielectric mirror based on free standing polymer layers. By applying an electrostatic force between the top and the bottom layers the reflectance can be changed. The large difference between the polymers refractive index and the air allows to achieve a reflectance of more than 85% using only six pairs of nanolayers. Preliminary simulations indicate an actuation speed of less than 1ms. Experimental optical characterization of fabricated structures agrees well with simulation results. Furthermore, structures can be designed to reflect a particular set of colors and/or isolated by using color filters, so a color pixel is fabricated, where the reflectance for each isolated color can be voltage controlled. Potential applications include an active component in a reflective screen display.

  9. Spectral behavior of a low-cost all-fiber component based on untapered multifiber unions

    OpenAIRE

    Rodriguez Horche, Paloma; López-Amo Sainz, Manuel; Muriel Fernández, Miguel Ángel; Martín Pereda, José Antonio

    1989-01-01

    Untapered multifiber unions are reported to show a spectral behavior similar to the tapered ones. Their oscillatory behavior does not depend on the biconical regions. This suggests a novel way to make low-cost all-fiber devices with applications as passive components such as optical filters and wavelength multiplexers/demultiplexers. Two types of multimode fibers have been studied and information about the index profile influence has been obtained. Polarization insensitivity and temperature s...

  10. Spectral analysis of pipe-to-soil potentials with variations of the Earth's magnetic field in the Australian region

    Science.gov (United States)

    Marshall, R. A.; Waters, C. L.; Sciffer, M. D.

    2010-05-01

    Long, steel pipelines used to transport essential resources such as gas and oil are potentially vulnerable to space weather. In order to inhibit corrosion, the pipelines are usually coated in an insulating material and maintained at a negative electric potential with respect to Earth using cathodic protection units. During periods of enhanced geomagnetic activity, potential differences between the pipeline and surrounding soil (referred to as pipe-to-soil potentials (PSPs)) may exhibit large voltage swings which place the pipeline outside the recommended "safe range" and at an increased risk of corrosion. The PSP variations result from the "geoelectric" field at the Earth's surface and associated geomagnetic field variations. Previous research investigating the relationship between the surface geoelectric field and geomagnetic source fields has focused on the high-latitude regions where line currents in the ionosphere E region are often the assumed source of the geomagnetic field variations. For the Australian region Sq currents also contribute to the geomagnetic field variations and provide the major contribution during geomagnetic quiet times. This paper presents the results of a spectral analysis of PSP measurements from four pipeline networks from the Australian region with geomagnetic field variations from nearby magnetometers. The pipeline networks extend from Queensland in the north of Australia to Tasmania in the south and provide PSP variations during both active and quiet geomagnetic conditions. The spectral analyses show both consistent phase and amplitude relationships across all pipelines, even for large separations between magnetometer and PSP sites and for small-amplitude signals. Comparison between the observational relationships and model predictions suggests a method for deriving a geoelectric field proxy suitable for indicating PSP-related space weather conditions.

  11. VIBRATIONS DETECTION IN INDUSTRIAL PUMPS BASED ON SPECTRAL ANALYSIS TO INCREASE THEIR EFFICIENCY

    Directory of Open Access Journals (Sweden)

    Belhadef RACHID

    2016-01-01

    Full Text Available Spectral analysis is the key tool for the study of vibration signals in rotating machinery. In this work, the vibration analy-sis applied for conditional preventive maintenance of such machines is proposed, as part of resolved problems related to vibration detection on the organs of these machines. The vibration signal of a centrifugal pump was treated to mount the benefits of the approach proposed. The obtained results present the signal estimation of a pump vibration using Fourier transform technique compared by the spectral analysis methods based on Prony approach.

  12. Spectral matching research for light-emitting diode-based neonatal jaundice therapeutic device light source

    Science.gov (United States)

    Gan, Ruting; Guo, Zhenning; Lin, Jieben

    2015-09-01

    To decrease the risk of bilirubin encephalopathy and minimize the need for exchange transfusions, we report a novel design for light source of light-emitting diode (LED)-based neonatal jaundice therapeutic device (NJTD). The bilirubin absorption spectrum in vivo was regarded as target. Based on spectral constructing theory, we used commercially available LEDs with different peak wavelengths and full width at half maximum as matching light sources. Simple genetic algorithm was first proposed as the spectral matching method. The required LEDs number at each peak wavelength was calculated, and then, the commercial light source sample model of the device was fabricated to confirm the spectral matching technology. In addition, the corresponding spectrum was measured and the effect was analyzed finally. The results showed that fitted spectrum was very similar to the target spectrum with 98.86 % matching degree, and the actual device model has a spectrum close to the target with 96.02 % matching degree. With higher fitting degree and efficiency, this matching algorithm is very suitable for light source matching technology of LED-based spectral distribution, and bilirubin absorption spectrum in vivo will be auspicious candidate for the target spectrum of new LED-based NJTD light source.

  13. Classification of Clean and Dirty Pighouse Surfaces Based on Spectral Reflectance

    DEFF Research Database (Denmark)

    Blanke, Mogens; Braithwaite, Ian David; Zhang, Guo-Qiang

    2004-01-01

    of designing a vision based system to locate dirty areas and subsequently direct a cleaning robot to remove dirt. Novel results include the characterisation of the spectral reflectance of real surfaces and dirt in a pig house and the design of illumination to obtain discrimination of clean from dirty areas...

  14. Data depth and rank-based tests for covariance and spectral density matrices

    KAUST Repository

    Chau, Joris

    2017-06-26

    In multivariate time series analysis, objects of primary interest to study cross-dependences in the time series are the autocovariance or spectral density matrices. Non-degenerate covariance and spectral density matrices are necessarily Hermitian and positive definite, and our primary goal is to develop new methods to analyze samples of such matrices. The main contribution of this paper is the generalization of the concept of statistical data depth for collections of covariance or spectral density matrices by exploiting the geometric properties of the space of Hermitian positive definite matrices as a Riemannian manifold. This allows one to naturally characterize most central or outlying matrices, but also provides a practical framework for rank-based hypothesis testing in the context of samples of covariance or spectral density matrices. First, the desired properties of a data depth function acting on the space of Hermitian positive definite matrices are presented. Second, we propose two computationally efficient pointwise and integrated data depth functions that satisfy each of these requirements. Several applications of the developed methodology are illustrated by the analysis of collections of spectral matrices in multivariate brain signal time series datasets.

  15. Spectral data based vegetation indices to characterise crop growth parameters and radiation interception in brassica

    International Nuclear Information System (INIS)

    Kar, G.; Chakravarty, N.V.K.

    2001-01-01

    Four spectral data based vegetation indices viz., infra-red/red (IR/R) ratio, normalized difference (N.D.), greenness index (GNI) and brightness index (BNI) were derived to characterise leaf area index, above ground biomass production and intercepted photosynthetically active radiation in Brassica oilseed crop. It was found from correlation study among different spectral indices, plant growth parameters and radiation interception that there was strong relationship between infrared/red and normalized difference with green area index for all the three Brassica cultivars whereas these spectral were not significantly correlated with above ground biomass. On the other hand, the brightness and greenness indices were closely correlated with above groundry biomass as compared to infrared/red ratio and normalized difference. All the four spectral indices were correlated with intercepted photosynthetically active radiation (IP AR). The best fit equations relating them were derived, which can be incorporated in the algorithms of crop growth simulation model to estimate plant growth parameters and radiation interception using spectral indices

  16. Discrimination and streaming of speech sounds based on differences in interaural and spectral cues.

    Science.gov (United States)

    David, Marion; Lavandier, Mathieu; Grimault, Nicolas; Oxenham, Andrew J

    2017-09-01

    Differences in spatial cues, including interaural time differences (ITDs), interaural level differences (ILDs) and spectral cues, can lead to stream segregation of alternating noise bursts. It is unknown how effective such cues are for streaming sounds with realistic spectro-temporal variations. In particular, it is not known whether the high-frequency spectral cues associated with elevation remain sufficiently robust under such conditions. To answer these questions, sequences of consonant-vowel tokens were generated and filtered by non-individualized head-related transfer functions to simulate the cues associated with different positions in the horizontal and median planes. A discrimination task showed that listeners could discriminate changes in interaural cues both when the stimulus remained constant and when it varied between presentations. However, discrimination of changes in spectral cues was much poorer in the presence of stimulus variability. A streaming task, based on the detection of repeated syllables in the presence of interfering syllables, revealed that listeners can use both interaural and spectral cues to segregate alternating syllable sequences, despite the large spectro-temporal differences between stimuli. However, only the full complement of spatial cues (ILDs, ITDs, and spectral cues) resulted in obligatory streaming in a task that encouraged listeners to integrate the tokens into a single stream.

  17. Superpixel segmentation and pigment identification of colored relics based on visible spectral image

    Science.gov (United States)

    Li, Junfeng; Wan, Xiaoxia

    2018-01-01

    To enrich the contents of digital archive and to guide the copy and restoration of colored relics, non-invasive methods for extraction of painting boundary and identification of pigment composition are proposed in this study based on the visible spectral images of colored relics. Superpixel concept is applied for the first time to the field of oversegmentation of visible spectral images and implemented on the visible spectral images of colored relics to extract their painting boundary. Since different pigments are characterized by their own spectrum and the same kind of pigment has the similar geometric profile in spectrum, an automatic identification method is established by comparing the proximity between the geometric profiles of the unknown spectrum from each superpixel and the pre-known spectrum from a deliberately prepared database. The methods are validated using the visible spectral images of the ancient wall paintings in Mogao Grottoes. By the way, the visible spectral images are captured by a multispectral imaging system consisting of two broadband filters and a RGB camera with high spatial resolution.

  18. Data depth and rank-based tests for covariance and spectral density matrices

    KAUST Repository

    Chau, Joris; Ombao, Hernando; Sachs, Rainer von

    2017-01-01

    In multivariate time series analysis, objects of primary interest to study cross-dependences in the time series are the autocovariance or spectral density matrices. Non-degenerate covariance and spectral density matrices are necessarily Hermitian and positive definite, and our primary goal is to develop new methods to analyze samples of such matrices. The main contribution of this paper is the generalization of the concept of statistical data depth for collections of covariance or spectral density matrices by exploiting the geometric properties of the space of Hermitian positive definite matrices as a Riemannian manifold. This allows one to naturally characterize most central or outlying matrices, but also provides a practical framework for rank-based hypothesis testing in the context of samples of covariance or spectral density matrices. First, the desired properties of a data depth function acting on the space of Hermitian positive definite matrices are presented. Second, we propose two computationally efficient pointwise and integrated data depth functions that satisfy each of these requirements. Several applications of the developed methodology are illustrated by the analysis of collections of spectral matrices in multivariate brain signal time series datasets.

  19. Retrieval and analysis of atmospheric XCO2 using ground-based spectral observation.

    Science.gov (United States)

    Qin, Xiu-Chun; Lei, Li-Ping; Kawasaki, Masahiro; Masafumi, Ohashi; Takahiro, Kuroki; Zeng, Zhao-Cheng; Zhang, Bing

    2014-07-01

    Atmospheric CO2 column concentration (column-averaged dry air mole fractions of atmospheric carbon dioxide) data obtained by ground-based hyperspectral observation is an important source of data for the verification and improvement of the results of CO2 retrieval based on satellite hyperspectral observation. However, few studies have been conducted on atmospheric CO2 column concentration retrieval based on ground-based spectral hyperspectral observation in China. In the present study, we carried out the ground-based hyperspectral observation in Xilingol Grassland, Inner Mongolia of China by using an observation system which is consisted of an optical spectral analyzer, a sun tracker, and some other elements. The atmospheric CO2 column concentration was retrieved using the observed hyperspectral data. The effect of a wavelength shift of the observation spectra and the meteorological parameters on the retrieval precision of the atmospheric CO2 concentration was evaluated and analyzed. The results show that the mean value of atmospheric CO2 concentration was 390.9 microg x mL(-1) in the study area during the observing period from July to September. The shift of wavelength in the range between -0.012 and 0.042 nm will generally lead to 1 microg x mL(-1) deviation in the CO2 retrievals. This study also revealed that the spectral transmittance was sensitive to meteorological parameters in the wavelength range of 6 357-6 358, 6 360-6 361, and 6 363-6 364 cm(-1). By comparing the CO2 retrievals derived from the meteorological parameters observed in synchronous and non-synchronous time, respectively, with the spectral observation, it was showed that the concentration deviation caused by using the non-synchronously observed meteorological parameters is ranged from 0.11 to 4 microg x mL(-1). These results can be used as references for the further improvement of retrieving CO2 column concentration based on spectral observation.

  20. Determination of the variation of mercury isotope concentration based on spectral-phase effects

    International Nuclear Information System (INIS)

    Ganeev, A.A.; Man', D.D.; Turkin, Yu.I.

    1988-01-01

    A method of isotopic atomic-absorption analysis, based on spectral-phase effects in which there is no need to use several sources of radiation with pure isotopes of the analyte element, was developed. The method made it possible to simplify the analysis and to determine the variation of the concentration of mercury isotopes from one deposit to another with an accuracy several times higher that of traditional methods of spectral isotopic analysis. The method was tested on mercury 198 and mercury 202. The isotopic analyzer is diagramed and described. The mechanism of spectral-phase effects was determined by the difference in effective photon lifetimes, corresponding to different components of the hyperfine structure of the resonance line of mercury at 254 nm

  1. Wave propagation numerical models in damage detection based on the time domain spectral element method

    International Nuclear Information System (INIS)

    Ostachowicz, W; Kudela, P

    2010-01-01

    A Spectral Element Method is used for wave propagation modelling. A 3D solid spectral element is derived with shape functions based on Lagrange interpolation and Gauss-Lobatto-Legendre points. This approach is applied for displacement approximation suited for fundamental modes of Lamb waves as well as potential distribution in piezoelectric transducers. The novelty is the model geometry extension from flat to curved elements for application in shell-like structures. Exemplary visualisations of waves excited by the piezoelectric transducers in curved shell structure made of aluminium alloy are presented. Simple signal analysis of wave interaction with crack is performed. The crack is modelled by separation of appropriate nodes between elements. An investigation of influence of the crack length on wave propagation signals is performed. Additionally, some aspects of the spectral element method implementation are discussed.

  2. Hyperspectral Image Classification Based on the Combination of Spatial-spectral Feature and Sparse Representation

    Directory of Open Access Journals (Sweden)

    YANG Zhaoxia

    2015-07-01

    Full Text Available In order to avoid the problem of being over-dependent on high-dimensional spectral feature in the traditional hyperspectral image classification, a novel approach based on the combination of spatial-spectral feature and sparse representation is proposed in this paper. Firstly, we extract the spatial-spectral feature by reorganizing the local image patch with the first d principal components(PCs into a vector representation, followed by a sorting scheme to make the vector invariant to local image rotation. Secondly, we learn the dictionary through a supervised method, and use it to code the features from test samples afterwards. Finally, we embed the resulting sparse feature coding into the support vector machine(SVM for hyperspectral image classification. Experiments using three hyperspectral data show that the proposed method can effectively improve the classification accuracy comparing with traditional classification methods.

  3. Investigation of solar flares in X-ray and optical spectral region

    International Nuclear Information System (INIS)

    Kurt, V.; Kurochka, L.N.; Zenchenko, V.M.

    1989-01-01

    Measurements of hard X h radiation of 180 solar flares carried out on board of the space probes Venera-13,-14, were compared with measurements of optical and thermal X t radiation. Values of total energy release during a flare in these regions are calculated, and correlation analysis is carried out. The bond correlations found have shown that total energy of fast electrons, caused X h -flare in the flare pulse phase, and thermal energy at the end of a pulse phase are practically connected with each othesr functionally. Quantitative connection between a flare ball in H α -line and the most probable energy values, being in different radiation regions calculated in the scope of generally accepted models, is established. The total energy of an optical (cold) part of the flare, radiation energy in X-ray region and the energy introduced to the flare volume by energy particles are shown to be compared between each other

  4. All-optical OFDM system using a wavelength selective switch based transmitter and a spectral magnification based receiver

    DEFF Research Database (Denmark)

    Guan, Pengyu; Lefrancois, S.; Lillieholm, Mads

    2014-01-01

    We demonstrate an AO-OFDM system with a WSS-based transmitter and time-lens based receiver for spectral magnification, achieving BER~10-9 for a 28×10 Gbit/s DPSK AO-OFDM signal. Furthermore, the receiver performance for DPSK and DQPSK is investigated using Monte Carlo simulations....

  5. Spectral reflectance study of the Hadley-Appenine (Apollo 15) region

    International Nuclear Information System (INIS)

    Lucey, P.G.; Hawke, B.R.

    1985-01-01

    Twenty three near infrared spectra were obtained from the Mauna Kea Observatory 2.2 m telescope. Results of an analysis of near infrared spectra obtained for surface units in the Hadley-Apennine region were presented. Compositional trends from the interior to exterior of the Imbrium are discussed

  6. Representations of Spectral Differences between Vowels in Tonotopic Regions of Auditory Cortex

    Science.gov (United States)

    Fisher, Julia

    2017-01-01

    This work examines the link between low-level cortical acoustic processing and higher-level cortical phonemic processing. Specifically, using functional magnetic resonance imaging, it looks at 1) whether or not the vowels [alpha] and [i] are distinguishable in regions of interest defined by the first two resonant frequencies (formants) of those…

  7. Parametric Explosion Spectral Model

    Energy Technology Data Exchange (ETDEWEB)

    Ford, S R; Walter, W R

    2012-01-19

    Small underground nuclear explosions need to be confidently detected, identified, and characterized in regions of the world where they have never before occurred. We develop a parametric model of the nuclear explosion seismic source spectrum derived from regional phases that is compatible with earthquake-based geometrical spreading and attenuation. Earthquake spectra are fit with a generalized version of the Brune spectrum, which is a three-parameter model that describes the long-period level, corner-frequency, and spectral slope at high-frequencies. Explosion spectra can be fit with similar spectral models whose parameters are then correlated with near-source geology and containment conditions. We observe a correlation of high gas-porosity (low-strength) with increased spectral slope. The relationship between the parametric equations and the geologic and containment conditions will assist in our physical understanding of the nuclear explosion source.

  8. Spectral embedding-based registration (SERg) for multimodal fusion of prostate histology and MRI

    Science.gov (United States)

    Hwuang, Eileen; Rusu, Mirabela; Karthigeyan, Sudha; Agner, Shannon C.; Sparks, Rachel; Shih, Natalie; Tomaszewski, John E.; Rosen, Mark; Feldman, Michael; Madabhushi, Anant

    2014-03-01

    Multi-modal image registration is needed to align medical images collected from different protocols or imaging sources, thereby allowing the mapping of complementary information between images. One challenge of multimodal image registration is that typical similarity measures rely on statistical correlations between image intensities to determine anatomical alignment. The use of alternate image representations could allow for mapping of intensities into a space or representation such that the multimodal images appear more similar, thus facilitating their co-registration. In this work, we present a spectral embedding based registration (SERg) method that uses non-linearly embedded representations obtained from independent components of statistical texture maps of the original images to facilitate multimodal image registration. Our methodology comprises the following main steps: 1) image-derived textural representation of the original images, 2) dimensionality reduction using independent component analysis (ICA), 3) spectral embedding to generate the alternate representations, and 4) image registration. The rationale behind our approach is that SERg yields embedded representations that can allow for very different looking images to appear more similar, thereby facilitating improved co-registration. Statistical texture features are derived from the image intensities and then reduced to a smaller set by using independent component analysis to remove redundant information. Spectral embedding generates a new representation by eigendecomposition from which only the most important eigenvectors are selected. This helps to accentuate areas of salience based on modality-invariant structural information and therefore better identifies corresponding regions in both the template and target images. The spirit behind SERg is that image registration driven by these areas of salience and correspondence should improve alignment accuracy. In this work, SERg is implemented using Demons

  9. Photometric behavior of spectral parameters in Vesta dark and bright regions as inferred by the Dawn VIR spectrometer

    Science.gov (United States)

    Longobardo, Andrea; Palomba, Ernesto; Capaccioni, Fabrizio; De Sanctis, Maria Cristina; Tosi, Federico; Ammannito, Eleonora; Schröder, Stefan E.; Zambon, Francesca; Raymond, Carol A.; Russell, Christopher T.

    2014-09-01

    NASA’s Dawn spacecraft orbited Vesta for approximately one year, collecting thousands of hyperspectral images of its surface. The mission revealed that Vesta’s surface shows the largest variations in surface albedo on asteroids visited thus far, due to the presence of dark and bright materials at the local scale (i.e. 0.1-10 km). The aim of this work is to characterize the photometric properties of bright and dark regions, and thus derive and apply an empirical photometric correction to all the hyperspectral observations of Vesta. The very large dataset (i.e. more than 20 million spectra) provided by the VIR imaging spectrometer onboard Dawn enabled accurate statistical analysis of the spectral dataset, aimed at retrieving empirical relations between several spectral parameters (i.e. visible and infrared reflectance, band depths, band centers, Band Area Ratio) and the illumination/viewing angles. The derived relations made it possible to derive photometrically corrected maps of these spectral parameters and to infer information on the regolith shadowing effect in the Vestan dark and bright regions. As an additional analysis, we also evaluated the correlation between surface temperature and band center position. A general conclusion of this analysis is that, from a photometric point of view, the distinction between bright and dark material units lies mainly in the larger contribution due to multiple scattering in the bright units. We observed reflectance and band depth variations over Vesta’s entire surface, but these variations were much larger in the dark regions than in the bright ones. Band centers have been found to shift to longer wavelengths at increasing temperatures, with a trend that is the same observed for HED meteorites (Reddy et al. [2012]. Icarus 217, 153-158). Finally, the Band Area Ratio (i.e. the ratio between areas of the main pyroxene absorption bands located at 1.9 μm and at 0.9 μm, respectively) did not show any dependence on

  10. Brillouin Scattering Spectrum Analysis Based on Auto-Regressive Spectral Estimation

    Science.gov (United States)

    Huang, Mengyun; Li, Wei; Liu, Zhangyun; Cheng, Linghao; Guan, Bai-Ou

    2018-06-01

    Auto-regressive (AR) spectral estimation technology is proposed to analyze the Brillouin scattering spectrum in Brillouin optical time-domain refelectometry. It shows that AR based method can reliably estimate the Brillouin frequency shift with an accuracy much better than fast Fourier transform (FFT) based methods provided the data length is not too short. It enables about 3 times improvement over FFT at a moderate spatial resolution.

  11. Brillouin Scattering Spectrum Analysis Based on Auto-Regressive Spectral Estimation

    Science.gov (United States)

    Huang, Mengyun; Li, Wei; Liu, Zhangyun; Cheng, Linghao; Guan, Bai-Ou

    2018-03-01

    Auto-regressive (AR) spectral estimation technology is proposed to analyze the Brillouin scattering spectrum in Brillouin optical time-domain refelectometry. It shows that AR based method can reliably estimate the Brillouin frequency shift with an accuracy much better than fast Fourier transform (FFT) based methods provided the data length is not too short. It enables about 3 times improvement over FFT at a moderate spatial resolution.

  12. Observed Spectral Invariant Behavior of Zenith Radiance in the Transition Zone Between Cloud-Free and Cloudy Regions

    Science.gov (United States)

    Marshak, A.; Knyazikhin, Y.; Chiu, C.; Wiscombe, W.

    2010-01-01

    The Atmospheric Radiation Measurement Program's (ARM) new Shortwave Spectrometer (SWS) looks straight up and measures zenith radiance at 418 wavelengths between 350 and 2200 nm. Because of its 1-sec sampling resolution, the SWS provides a unique capability to study the transition zone between cloudy and clear sky areas. A surprising spectral invariant behavior is found between ratios of zenith radiance spectra during the transition from cloudy to cloud-free atmosphere. This behavior suggests that the spectral signature of the transition zone is a linear mixture between the two extremes (definitely cloudy and definitely clear). The weighting function of the linear mixture is found to be a wavelength-independent characteristic of the transition zone. It is shown that the transition zone spectrum is fully determined by this function and zenith radiance spectra of clear and cloudy regions. This new finding may help us to better understand and quantify such physical phenomena as humidification of aerosols in the relatively moist cloud environment and evaporation and activation of cloud droplets.

  13. Optimal depth-based regional frequency analysis

    Directory of Open Access Journals (Sweden)

    H. Wazneh

    2013-06-01

    Full Text Available Classical methods of regional frequency analysis (RFA of hydrological variables face two drawbacks: (1 the restriction to a particular region which can lead to a loss of some information and (2 the definition of a region that generates a border effect. To reduce the impact of these drawbacks on regional modeling performance, an iterative method was proposed recently, based on the statistical notion of the depth function and a weight function φ. This depth-based RFA (DBRFA approach was shown to be superior to traditional approaches in terms of flexibility, generality and performance. The main difficulty of the DBRFA approach is the optimal choice of the weight function ϕ (e.g., φ minimizing estimation errors. In order to avoid a subjective choice and naïve selection procedures of φ, the aim of the present paper is to propose an algorithm-based procedure to optimize the DBRFA and automate the choice of ϕ according to objective performance criteria. This procedure is applied to estimate flood quantiles in three different regions in North America. One of the findings from the application is that the optimal weight function depends on the considered region and can also quantify the region's homogeneity. By comparing the DBRFA to the canonical correlation analysis (CCA method, results show that the DBRFA approach leads to better performances both in terms of relative bias and mean square error.

  14. Optimal depth-based regional frequency analysis

    Science.gov (United States)

    Wazneh, H.; Chebana, F.; Ouarda, T. B. M. J.

    2013-06-01

    Classical methods of regional frequency analysis (RFA) of hydrological variables face two drawbacks: (1) the restriction to a particular region which can lead to a loss of some information and (2) the definition of a region that generates a border effect. To reduce the impact of these drawbacks on regional modeling performance, an iterative method was proposed recently, based on the statistical notion of the depth function and a weight function φ. This depth-based RFA (DBRFA) approach was shown to be superior to traditional approaches in terms of flexibility, generality and performance. The main difficulty of the DBRFA approach is the optimal choice of the weight function ϕ (e.g., φ minimizing estimation errors). In order to avoid a subjective choice and naïve selection procedures of φ, the aim of the present paper is to propose an algorithm-based procedure to optimize the DBRFA and automate the choice of ϕ according to objective performance criteria. This procedure is applied to estimate flood quantiles in three different regions in North America. One of the findings from the application is that the optimal weight function depends on the considered region and can also quantify the region's homogeneity. By comparing the DBRFA to the canonical correlation analysis (CCA) method, results show that the DBRFA approach leads to better performances both in terms of relative bias and mean square error.

  15. All-dielectric KTiOPO4 metasurfaces based on multipolar resonances in the terahertz region

    DEFF Research Database (Denmark)

    Tian, Jingyi; Yang, Yuanqing; Qiu, Min

    2017-01-01

    We employ ferroelectrics to study the multipolar scattering in all-dielectric metasurfaces based on KTiOPO4 (KTP) micro-disks for efficient manipulation of electromagnetic waves in the THz spectral region (0.6-1.5 THz). By adjusting the aspect ratio of the disks near the multipolar resonances, we...

  16. Probabilistic full waveform inversion based on tectonic regionalization - development and application to the Australian upper mantle

    NARCIS (Netherlands)

    Käufl, P.; Fichtner, A.; Igel, H.

    2013-01-01

    We present a first study to investigate the feasibility of a probabilistic 3-D full waveform inversion based on spectral-element simulations of seismic wave propagation and Monte Carlo exploration of the model space. Through a tectonic regionalization we reduce the dimension of the model space to

  17. Dynamical Downscaling of Seasonal Climate Prediction over Nordeste Brazil with ECHAM3 and NCEP's Regional Spectral Models at IRI.

    Science.gov (United States)

    Nobre, Paulo; Moura, Antonio D.; Sun, Liqiang

    2001-12-01

    This study presents an evaluation of a seasonal climate forecast done with the International Research Institute for Climate Prediction (IRI) dynamical forecast system (regional model nested into a general circulation model) over northern South America for January-April 1999, encompassing the rainy season over Brazil's Nordeste. The one-way nesting is one in two tiers: first the NCEP's Regional Spectral Model (RSM) runs with an 80-km grid mesh forced by the ECHAM3 atmospheric general circulation model (AGCM) outputs; then the RSM runs with a finer grid mesh (20 km) forced by the forecasts generated by the RSM-80. An ensemble of three realizations is done. Lower boundary conditions over the oceans for both ECHAM and RSM model runs are sea surface temperature forecasts over the tropical oceans. Soil moisture is initialized by ECHAM's inputs. The rainfall forecasts generated by the regional model are compared with those of the AGCM and observations. It is shown that the regional model at 80-km resolution improves upon the AGCM rainfall forecast, reducing both seasonal bias and root-mean-square error. On the other hand, the RSM-20 forecasts presented larger errors, with spatial patterns that resemble those of local topography. The better forecast of the position and width of the intertropical convergence zone (ITCZ) over the tropical Atlantic by the RSM-80 model is one of the principal reasons for better-forecast scores of the RSM-80 relative to the AGCM. The regional model improved the spatial as well as the temporal details of rainfall distribution, and also presenting the minimum spread among the ensemble members. The statistics of synoptic-scale weather variability on seasonal timescales were best forecast with the regional 80-km model over the Nordeste. The possibility of forecasting the frequency distribution of dry and wet spells within the rainy season is encouraging.

  18. Spectral Analysis of Quantum-Dash Lasers: Effect of Inhomogeneous Broadening of the Active-Gain Region

    KAUST Repository

    Khan, Mohammed Zahed Mustafa; Ng, Tien Khee; Ooi, Boon S.; Schwingenschlö gl, Udo

    2012-01-01

    The effect of the active region inhomogeneity on the spectral characteristics of InAs/InP quantum-dash (Qdash) lasers is examined theoretically by solving the coupled set of carrier-photon rate equations. The inhomogeneity due to dash size or composition fluctuation is included in the model by considering dispersive energy states and characterized by a Gaussian envelope. In addition, the technique incorporates multilongitudinal photon modes and homogeneous broadening of the optical gain. The results predict a red shift in the central lasing wavelength of Qdash lasers on increasing the inhomogeneous broadening either explicitly or implicitly, which supports various experimental observations. The threshold current density and the lasing bandwidth are also found to increase. © 2012 IEEE.

  19. Spectral Analysis of Quantum-Dash Lasers: Effect of Inhomogeneous Broadening of the Active-Gain Region

    KAUST Repository

    Khan, Mohammed Zahed Mustafa

    2012-05-01

    The effect of the active region inhomogeneity on the spectral characteristics of InAs/InP quantum-dash (Qdash) lasers is examined theoretically by solving the coupled set of carrier-photon rate equations. The inhomogeneity due to dash size or composition fluctuation is included in the model by considering dispersive energy states and characterized by a Gaussian envelope. In addition, the technique incorporates multilongitudinal photon modes and homogeneous broadening of the optical gain. The results predict a red shift in the central lasing wavelength of Qdash lasers on increasing the inhomogeneous broadening either explicitly or implicitly, which supports various experimental observations. The threshold current density and the lasing bandwidth are also found to increase. © 2012 IEEE.

  20. Water vapor transmittance models for narrow bands in the 13 to 19 μm spectral region

    International Nuclear Information System (INIS)

    Weichel, R.L.

    1983-10-01

    The purpose of this report is to document the development of water vapor transmittance models for narrow bands (satellite sensor channels) in the 13 to 19 μm spectral region. The models are the result of research efforts of the author in 1971-1972 while on active duty with the US Air Force at the Air Force Global Weather Central (AFGWC). The models were developed for application in studies involving a temperature profiling sensor system carried aboard the satellites of the Defense Meteorological Satellite Program (DMSP), formerly DAPP. Recently, (Lovill et al., 1978; Luther et al., 1981) the models were implemented for studies concerned with methodologies to retrieve total atmospheric column ozone from measurements of newer DMSP Block 5D series satellite sensors with similar channels (see Nichols, 1975)

  1. Novel Cavities in Vertical External Cavity Surface Emitting Lasers for Emission in Broad Spectral Region by Means of Nonlinear Frequency Conversion

    Science.gov (United States)

    Lukowski, Michal L.

    Optically pumped semiconductor vertical external cavity surface emitting lasers (VECSEL) were first demonstrated in the mid 1990's. Due to the unique design properties of extended cavity lasers VECSELs have been able to provide tunable, high-output powers while maintaining excellent beam quality. These features offer a wide range of possible applications in areas such as medicine, spectroscopy, defense, imaging, communications and entertainment. Nowadays, newly developed VECSELs, cover the spectral regions from red (600 nm) to around 5 microm. By taking the advantage of the open cavity design, the emission can be further expanded to UV or THz regions by the means of intracavity nonlinear frequency generation. The objective of this dissertation is to investigate and extend the capabilities of high-power VECSELs by utilizing novel nonlinear conversion techniques. Optically pumped VECSELs based on GaAs semiconductor heterostructures have been demonstrated to provide exceptionally high output powers covering the 900 to 1200 nm spectral region with diffraction limited beam quality. The free space cavity design allows for access to the high intracavity circulating powers where high efficiency nonlinear frequency conversions and wavelength tuning can be obtained. As an introduction, this dissertation consists of a brief history of the development of VECSELs as well as wafer design, chip fabrication and resonator cavity design for optimal frequency conversion. Specifically, the different types of laser cavities such as: linear cavity, V-shaped cavity and patented T-shaped cavity are described, since their optimization is crucial for transverse mode quality, stability, tunability and efficient frequency conversion. All types of nonlinear conversions such as second harmonic, sum frequency and difference frequency generation are discussed in extensive detail. The theoretical simulation and the development of the high-power, tunable blue and green VECSEL by the means of type I

  2. Modelling the spectral irradiance distribution in sunny inland locations using an ANN-based methodology

    International Nuclear Information System (INIS)

    Torres-Ramírez, M.; Elizondo, D.; García-Domingo, B.; Nofuentes, G.; Talavera, D.L.

    2015-01-01

    This work is aimed at verifying that in sunny inland locations artificial intelligence techniques may provide an estimation of the spectral irradiance with adequate accuracy for photovoltaic applications. An ANN (artificial neural network) based method was developed, trained and tested to model the spectral distributions between wavelengths ranging from 350 to 1050 nm. Only commonly available input data such as geographical information regarding location, specific date and time together with horizontal global irradiance and ambient temperature are required. Historical information from a 24-month experimental campaign carried out in Jaén (Spain) provided the necessary data to train and test the ANN tool. A Kohonen self-organized map was used as innovative technique to classify the whole input dataset and build a small and representative training dataset. The shape of the spectral irradiance distribution, the in-plane global irradiance (G T ) and irradiation (H T ) and the APE (average photon energy) values obtained through the ANN method were statistically compared to the experimental ones. In terms of shape distribution fitting, the mean relative deformation error stays below 4.81%. The root mean square percentage error is around 6.89% and 0.45% when estimating G T and APE, respectively. Regarding H T , errors lie below 3.18% in all cases. - Highlights: • ANN-based model to estimate the spectral irradiance distribution in sunny inland locations. • MRDE value stay below 4.81% in spectral irradiance distribution shape fitting. • RMSPE is about 6.89% for the in-plane global irradiance and 0.45% for the average photon energy. • Errors stay below 3.18% for all the months of the year in incident irradiation terms. • Improvement of assessment of the impact of the solar spectrum in the performance of a PV module

  3. The impact of smoke from forest fires on the spectral dispersion of cloud droplet size distributions in the Amazonian region

    International Nuclear Information System (INIS)

    Martins, J A; Silva Dias, M A F

    2009-01-01

    In this paper, the main microphysical characteristics of clouds developing in polluted and clean conditions in the biomass-burning season of the Amazon region are examined, with special attention to the spectral dispersion of the cloud droplet size distribution and its potential impact on climate modeling applications. The dispersion effect has been shown to alter the climate cooling predicted by the so-called Twomey effect. In biomass-burning polluted conditions, high concentrations of low dispersed cloud droplets are found. Clean conditions revealed an opposite situation. The liquid water content (0.43 ± 0.19 g m -3 ) is shown to be uncorrelated with the cloud drop number concentration, while the effective radius is found to be very much correlated with the relative dispersion of the size distribution (R 2 = 0.81). The results suggest that an increase in cloud condensation nuclei concentration from biomass-burning aerosols may lead to an additional effect caused by a decrease in relative dispersion. Since the dry season in the Amazonian region is vapor limiting, the dispersion effect of cloud droplet size distributions could be substantially larger than in other polluted regions.

  4. A framelet-based iterative maximum-likelihood reconstruction algorithm for spectral CT

    Science.gov (United States)

    Wang, Yingmei; Wang, Ge; Mao, Shuwei; Cong, Wenxiang; Ji, Zhilong; Cai, Jian-Feng; Ye, Yangbo

    2016-11-01

    Standard computed tomography (CT) cannot reproduce spectral information of an object. Hardware solutions include dual-energy CT which scans the object twice in different x-ray energy levels, and energy-discriminative detectors which can separate lower and higher energy levels from a single x-ray scan. In this paper, we propose a software solution and give an iterative algorithm that reconstructs an image with spectral information from just one scan with a standard energy-integrating detector. The spectral information obtained can be used to produce color CT images, spectral curves of the attenuation coefficient μ (r,E) at points inside the object, and photoelectric images, which are all valuable imaging tools in cancerous diagnosis. Our software solution requires no change on hardware of a CT machine. With the Shepp-Logan phantom, we have found that although the photoelectric and Compton components were not perfectly reconstructed, their composite effect was very accurately reconstructed as compared to the ground truth and the dual-energy CT counterpart. This means that our proposed method has an intrinsic benefit in beam hardening correction and metal artifact reduction. The algorithm is based on a nonlinear polychromatic acquisition model for x-ray CT. The key technique is a sparse representation of iterations in a framelet system. Convergence of the algorithm is studied. This is believed to be the first application of framelet imaging tools to a nonlinear inverse problem.

  5. High-resolution narrowband CARS spectroscopy in the spectral fingerprint region

    NARCIS (Netherlands)

    Chimento, P.F.; Jurna, M.; Bouwmans, H.S.P.; Garbacik, E.T.; Garbacik, E.T.; Hartsuiker, Liesbeth; Otto, Cornelis; Herek, Jennifer Lynn; Offerhaus, Herman L.

    2010-01-01

    Coherent anti-Stokes Raman scattering (CARS) spectroscopy is an important technique for spectroscopy and chemically selective microscopy, but wider implementation requires dedicated versatile tunable sources. We describe an optical parametric oscillator (OPO) based on a magnesium oxide-doped

  6. Wavelet-based spectral finite element dynamic analysis for an axially moving Timoshenko beam

    Science.gov (United States)

    Mokhtari, Ali; Mirdamadi, Hamid Reza; Ghayour, Mostafa

    2017-08-01

    In this article, wavelet-based spectral finite element (WSFE) model is formulated for time domain and wave domain dynamic analysis of an axially moving Timoshenko beam subjected to axial pretension. The formulation is similar to conventional FFT-based spectral finite element (SFE) model except that Daubechies wavelet basis functions are used for temporal discretization of the governing partial differential equations into a set of ordinary differential equations. The localized nature of Daubechies wavelet basis functions helps to rule out problems of SFE model due to periodicity assumption, especially during inverse Fourier transformation and back to time domain. The high accuracy of WSFE model is then evaluated by comparing its results with those of conventional finite element and SFE results. The effects of moving beam speed and axial tensile force on vibration and wave characteristics, and static and dynamic stabilities of moving beam are investigated.

  7. Smoothing of Fused Spectral Consistent Satellite Images with TV-based Edge Detection

    DEFF Research Database (Denmark)

    Sveinsson, Johannes; Aanæs, Henrik; Benediktsson, Jon Atli

    2007-01-01

    based on satellite data. Additionally, most conventional methods are loosely connected to the image forming physics of the satellite image, giving these methods an ad hoc feel. Vesteinsson et al. [1] proposed a method of fusion of satellite images that is based on the properties of imaging physics...... in a statistically meaningful way and was called spectral consistent panshapening (SCP). In this paper we improve this framework for satellite image fusion by introducing a better image prior, via data-dependent image smoothing. The dependency is obtained via total variation edge detection method.......Several widely used methods have been proposed for fusing high resolution panchromatic data and lower resolution multi-channel data. However, many of these methods fail to maintain the spectral consistency of the fused high resolution image, which is of high importance to many of the applications...

  8. Atmospheric weighting functions and surface partial derivatives for remote sensing of scattering planetary atmospheres in thermal spectral region: general adjoint approach

    International Nuclear Information System (INIS)

    Ustinov, Eugene A.

    2005-01-01

    An approach to formulation of inversion algorithms for remote sensing in the thermal spectral region in the case of a scattering planetary atmosphere, based on the adjoint equation of radiative transfer (Ustinov (JQSRT 68 (2001) 195; JQSRT 73 (2002) 29); referred to as Papers 1 and 2, respectively, in the main text), is applied to the general case of retrievals of atmospheric and surface parameters for the scattering atmosphere with nadir viewing geometry. Analytic expressions for corresponding weighting functions for atmospheric parameters and partial derivatives for surface parameters are derived. The case of pure atmospheric absorption with a scattering underlying surface is considered and convergence to results obtained for the non-scattering atmospheres (Ustinov (JQSRT 74 (2002) 683), referred to as Paper 3 in the main text) is demonstrated

  9. Techniques for Handling and Removal of Spectral Channels in Fourier Transform Synchrotron-Based Spectra

    International Nuclear Information System (INIS)

    Ibrahim, Amr; Predoi-Cross, Adriana; Teillet, Philippe M.

    2010-01-01

    Channel spectra are a big problem for those attempting to use synchrotron-based Fourier transform spectra for spectral lineshape studies. Due to the layout of the optical system at the CLS far-infrared beamline, the synchrotron beam undergoes unavoidable multiple reflections on the steering mirrors, beam splitter, several sets of windows, and filters. We present a method for eliminating channel spectra and compare the results of our technique with other methods available in the literature.

  10. Spectral interference of zirconium on 24 analyte elements using CCD based ICP-AES technique

    International Nuclear Information System (INIS)

    Adya, V.C.; Sengupta, Arijit; Godbole, S.V.

    2014-01-01

    In the present studies, the spectral interference of zirconium on different analytical lines of 24 critical analytes using CCD based ICP-AES technique is described. Suitable analytical lines for zirconium were identified along with their detection limits. The sensitivity and the detection limits of analytical channels for different elements in presence of Zr matrix were calculated. Subsequently analytical lines with least interference from Zr and better detection limits were selected for their determinations. (author)

  11. Measurements and modeling of absorption by CO2 + H2O mixtures in the spectral region beyond the CO2 ν3-band head

    Science.gov (United States)

    Tran, H.; Turbet, M.; Chelin, P.; Landsheere, X.

    2018-05-01

    In this work, we measured the absorption by CO2 + H2O mixtures from 2400 to 2600 cm-1 which corresponds to the spectral region beyond the ν3 band head of CO2. Transmission spectra of CO2 mixed with water vapor were recorded with a high-resolution Fourier-transform spectrometer for various pressure, temperature and concentration conditions. The continuum absorption by CO2 due to the presence of water vapor was determined by subtracting from measured spectra the contribution of local lines of both species, that of the continuum of pure CO2 as well as of the self- and CO2-continua of water vapor induced by the H2O-H2O and H2O-CO2 interactions. The obtained results are in very good agreement with the unique previous measurement (in a narrower spectral range). They confirm that the H2O-continuum of CO2 is significantly larger than that observed for pure CO2. This continuum thus must be taken into account in radiative transfer calculations for media involving CO2+ H2O mixture. An empirical model, using sub-Lorentzian line shapes based on some temperature-dependent correction factors χ is proposed which enables an accurate description of the experimental results.

  12. [Research on developping the spectral dataset for Dunhuang typical colors based on color constancy].

    Science.gov (United States)

    Liu, Qiang; Wan, Xiao-Xia; Liu, Zhen; Li, Chan; Liang, Jin-Xing

    2013-11-01

    The present paper aims at developping a method to reasonably set up the typical spectral color dataset for different kinds of Chinese cultural heritage in color rendering process. The world famous wall paintings dating from more than 1700 years ago in Dunhuang Mogao Grottoes was taken as typical case in this research. In order to maintain the color constancy during the color rendering workflow of Dunhuang culture relics, a chromatic adaptation based method for developping the spectral dataset of typical colors for those wall paintings was proposed from the view point of human vision perception ability. Under the help and guidance of researchers in the art-research institution and protection-research institution of Dunhuang Academy and according to the existing research achievement of Dunhuang Research in the past years, 48 typical known Dunhuang pigments were chosen and 240 representative color samples were made with reflective spectral ranging from 360 to 750 nm was acquired by a spectrometer. In order to find the typical colors of the above mentioned color samples, the original dataset was devided into several subgroups by clustering analysis. The grouping number, together with the most typical samples for each subgroup which made up the firstly built typical color dataset, was determined by wilcoxon signed rank test according to the color inconstancy index comprehensively calculated under 6 typical illuminating conditions. Considering the completeness of gamut of Dunhuang wall paintings, 8 complementary colors was determined and finally the typical spectral color dataset was built up which contains 100 representative spectral colors. The analytical calculating results show that the median color inconstancy index of the built dataset in 99% confidence level by wilcoxon signed rank test was 3.28 and the 100 colors are distributing in the whole gamut uniformly, which ensures that this dataset can provide reasonable reference for choosing the color with highest

  13. Charged-current inclusive neutrino cross sections: superscaling extension to the pion production and realistic spectral function for quasielastic region

    International Nuclear Information System (INIS)

    Ivanov, A.N.; Antonov, M.V.; Barbaro, J.A.; Caballero, G.A.; Megias, G.D.; González-Jiménez, R.; Giusti, C.; Meucci, A.; Moya de Guerra, E.; Udías, J.M.

    2015-01-01

    Superscaling approximation (SuSA) predictions to neutrino-induced charged-current pion production in the Δ-resonance region are explored under MiniBooNE experimental conditions. The results obtained within SuSA for the flux-averaged double-differential cross sections of the pion production for the ν_μ+CH_2 reaction as a function of the muon kinetic energy and of the scattering angle, the cross sections averaged over the angle, the total cross section for the pion production are compared with the corresponding MiniBooNE experimental data. The SuSA charged-current π"+ predictions are in good agreement with data on neutrino flux average cross-sections. The SuSA extension to the pion production region and the realistic spectral function S(p;ε) for quasielastic scattering are used for predictions of charged current inclusive neutrino-nucleus cross sections. The results are compared with the inclusive neutrino-nucleus data from the T2K experiment. (author)

  14. Spectral Unmixing Modeling of the Aristarchus Pyroclastic Deposit: Assessing the Eruptive History of Glass-Rich Regional Lunar Pyroclastic Deposits

    Science.gov (United States)

    Jawin, E. R.; Head, J. W., III; Cannon, K.

    2017-12-01

    The Aristarchus pyroclastic deposit in central Oceanus Procellarum is understood to have formed in a gas-rich explosive volcanic eruption, and has been observed to contain abundant volcanic glass. However, the interpreted color (and therefore composition) of the glass has been debated. In addition, previous analyses of the pyroclastic deposit have been performed using lower resolution data than are currently available. In this work, a nonlinear spectral unmixing model was applied to Moon Mineralogy Mapper (M3) data of the Aristarchus plateau to investigate the detailed mineralogic and crystalline nature of the Aristarchus pyroclastic deposit by using spectra of laboratory endmembers including a suite of volcanic glasses returned from the Apollo 15 and 17 missions (green, orange, black beads), as well as synthetic lunar glasses (orange, green, red, yellow). Preliminary results of the M3 unmixing model suggest that spectra of the pyroclastic deposit can be modeled by a mixture composed predominantly of a featureless endmember approximating space weathering and a smaller component of glass. The modeled spectra were most accurate with a synthetic orange glass endmember, relative to the other glasses analyzed in this work. The results confirm that there is a detectable component of glass in the Aristarchus pyroclastic deposit which may be similar to the high-Ti orange glass seen in other regional pyroclastic deposits, with only minimal contributions of other crystalline minerals. The presence of volcanic glass in the pyroclastic deposit, with the low abundance of crystalline material, would support the model that the Aristarchus pyroclastic deposit formed in a long-duration, hawaiian-style fire fountain eruption. No significant detection of devitrified black beads in the spectral modeling results (as was observed at the Apollo 17 landing site in the Taurus-Littrow pyroclastic deposit), suggests the optical density of the eruptive plume remained low throughout the

  15. A reflectivity profilometer for the optical characterisation of grade reflectivity mirrors in the 250 nm - 1100 nm spectral region

    Energy Technology Data Exchange (ETDEWEB)

    Colucci, Alessandro; Nichelatti, Enrico [ENEA, Centro Ricerche Casaccia, Rome (Italy). Dipt. Innovazione

    1998-04-01

    It`s developed the prototype of an instrument that can be used for the optical characterisation of graded reflectivity mirrors at any wavelength in the spectral region from 250 nm to 1100 nm. The instrument utilises a high-pressure Xe arc lamp as light source. Light is spectrally filtered by means of a grating monochromator. The sample is illuminated with an image of the monochromator exit slit. After reflection from the sample, this image is projected onto a 1024-elements charge-coupled device linear array driven by a digital frame board and interfaced with a personal computer. It`s tested the instrument accuracy by comparing measurement results with the corresponding ones obtained by means of a laser scanning technique. Measurement Rms repeatability has been estimated to be approximately of 0.8%. [Italiano] E` stato sviluppato il prototipo di uno strumento per la catatterizzazione ottica di specchi a riflettivita` variabile, operante a qualsiasi lunghezza d`onda nell`intervallo spettrale da 250 nm a 1100 nm. La sorgente dello strumento e` una lampada ad arco allo Xenon ad alta pressione. La luce e` filtrata spettralmente per mezzo di un monocromatore a reticolo. Il campione viene illuminato da un`immagine della fenditura d`uscita del monocromatore. Dopo essere stata riflessa dal campione, questa immagine viene proiettata su un array CCD lineare a 1024 elementi, connesso elettronicamente a una scheda digitale e interfacciato a un personal computer. L`accuratezza dello strumento e` stata verificata confrontando alcune misure con le corrispondenti misure ottenute mediante una tecnica a scansione laser. La ripetibilita` RMS delle misure e` stata stimata essere circa dello 0.8%.

  16. Assessing the Impact of Spectral Resolution on Classification of Lowland Native Grassland Communities Based on Field Spectroscopy in Tasmania, Australia

    Directory of Open Access Journals (Sweden)

    Bethany Melville

    2018-02-01

    Full Text Available This paper presents a case study for the analysis of endangered lowland native grassland communities in the Tasmanian Midlands region using field spectroscopy and spectral convolution techniques. The aim of the study was to determine whether there was significant improvement in classification accuracy for lowland native grasslands and other vegetation communities based on hyperspectral resolution datasets over multispectral equivalents. A spectral dataset was collected using an ASD Handheld-2 spectroradiometer at Tunbridge Township Lagoon. The study then employed a k-fold cross-validation approach for repeated classification of a full hyperspectral dataset, a reduced hyperspectral dataset, and two convoluted multispectral datasets. Classification was performed on each of the four datasets a total of 30 times, based on two different class configurations. The classes analysed were Themeda triandra grassland, Danthonia/Poa grassland, Wilsonia rotundifolia/Selliera radicans, saltpan, and a simplified C3 vegetation class. The results of the classifications were then tested for statistically significant differences using ANOVA and Tukey’s post-hoc comparisons. The results of the study indicated that hyperspectral resolution provides small but statistically significant increases in classification accuracy for Themeda and Danthonia grasslands. For other classes, differences in classification accuracy for all datasets were not statistically significant. The results obtained here indicate that there is some potential for enhanced detection of major lowland native grassland community types using hyperspectral resolution datasets, and that future analysis should prioritise good performance in these classes over others. This study presents a method for identification of optimal spectral resolution across multiple datasets, and constitutes an important case study for lowland native grassland mapping in Tasmania.

  17. Asymptotic stability of spectral-based PDF modeling for homogeneous turbulent flows

    Science.gov (United States)

    Campos, Alejandro; Duraisamy, Karthik; Iaccarino, Gianluca

    2015-11-01

    Engineering models of turbulence, based on one-point statistics, neglect spectral information inherent in a turbulence field. It is well known, however, that the evolution of turbulence is dictated by a complex interplay between the spectral modes of velocity. For example, for homogeneous turbulence, the pressure-rate-of-strain depends on the integrated energy spectrum weighted by components of the wave vectors. The Interacting Particle Representation Model (IPRM) (Kassinos & Reynolds, 1996) and the Velocity/Wave-Vector PDF model (Van Slooten & Pope, 1997) emulate spectral information in an attempt to improve the modeling of turbulence. We investigate the evolution and asymptotic stability of the IPRM using three different approaches. The first approach considers the Lagrangian evolution of individual realizations (idealized as particles) of the stochastic process defined by the IPRM. The second solves Lagrangian evolution equations for clusters of realizations conditional on a given wave vector. The third evolves the solution of the Eulerian conditional PDF corresponding to the aforementioned clusters. This last method avoids issues related to discrete particle noise and slow convergence associated with Lagrangian particle-based simulations.

  18. Accurate palm vein recognition based on wavelet scattering and spectral regression kernel discriminant analysis

    Science.gov (United States)

    Elnasir, Selma; Shamsuddin, Siti Mariyam; Farokhi, Sajad

    2015-01-01

    Palm vein recognition (PVR) is a promising new biometric that has been applied successfully as a method of access control by many organizations, which has even further potential in the field of forensics. The palm vein pattern has highly discriminative features that are difficult to forge because of its subcutaneous position in the palm. Despite considerable progress and a few practical issues, providing accurate palm vein readings has remained an unsolved issue in biometrics. We propose a robust and more accurate PVR method based on the combination of wavelet scattering (WS) with spectral regression kernel discriminant analysis (SRKDA). As the dimension of WS generated features is quite large, SRKDA is required to reduce the extracted features to enhance the discrimination. The results based on two public databases-PolyU Hyper Spectral Palmprint public database and PolyU Multi Spectral Palmprint-show the high performance of the proposed scheme in comparison with state-of-the-art methods. The proposed approach scored a 99.44% identification rate and a 99.90% verification rate [equal error rate (EER)=0.1%] for the hyperspectral database and a 99.97% identification rate and a 99.98% verification rate (EER=0.019%) for the multispectral database.

  19. Improving the spectral measurement accuracy based on temperature distribution and spectra-temperature relationship

    Science.gov (United States)

    Li, Zhe; Feng, Jinchao; Liu, Pengyu; Sun, Zhonghua; Li, Gang; Jia, Kebin

    2018-05-01

    Temperature is usually considered as a fluctuation in near-infrared spectral measurement. Chemometric methods were extensively studied to correct the effect of temperature variations. However, temperature can be considered as a constructive parameter that provides detailed chemical information when systematically changed during the measurement. Our group has researched the relationship between temperature-induced spectral variation (TSVC) and normalized squared temperature. In this study, we focused on the influence of temperature distribution in calibration set. Multi-temperature calibration set selection (MTCS) method was proposed to improve the prediction accuracy by considering the temperature distribution of calibration samples. Furthermore, double-temperature calibration set selection (DTCS) method was proposed based on MTCS method and the relationship between TSVC and normalized squared temperature. We compare the prediction performance of PLS models based on random sampling method and proposed methods. The results from experimental studies showed that the prediction performance was improved by using proposed methods. Therefore, MTCS method and DTCS method will be the alternative methods to improve prediction accuracy in near-infrared spectral measurement.

  20. Spectral optimization simulation of white light based on the photopic eye-sensitivity curve

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Qi, E-mail: qidai@tongji.edu.cn [College of Architecture and Urban Planning, Tongji University, 1239 Siping Road, Shanghai 200092 (China); Institute for Advanced Study, Tongji University, 1239 Siping Road, Shanghai 200092 (China); Key Laboratory of Ecology and Energy-saving Study of Dense Habitat (Tongji University), Ministry of Education, 1239 Siping Road, Shanghai 200092 (China); Hao, Luoxi; Lin, Yi; Cui, Zhe [College of Architecture and Urban Planning, Tongji University, 1239 Siping Road, Shanghai 200092 (China); Key Laboratory of Ecology and Energy-saving Study of Dense Habitat (Tongji University), Ministry of Education, 1239 Siping Road, Shanghai 200092 (China)

    2016-02-07

    Spectral optimization simulation of white light is studied to boost maximum attainable luminous efficacy of radiation at high color-rendering index (CRI) and various color temperatures. The photopic eye-sensitivity curve V(λ) is utilized as the dominant portion of white light spectra. Emission spectra of a blue InGaN light-emitting diode (LED) and a red AlInGaP LED are added to the spectrum of V(λ) to match white color coordinates. It is demonstrated that at the condition of color temperature from 2500 K to 6500 K and CRI above 90, such white sources can achieve spectral efficacy of 330–390 lm/W, which is higher than the previously reported theoretical maximum values. We show that this eye-sensitivity-based approach also has advantages on component energy conversion efficiency compared with previously reported optimization solutions.

  1. Spectral optimization simulation of white light based on the photopic eye-sensitivity curve

    International Nuclear Information System (INIS)

    Dai, Qi; Hao, Luoxi; Lin, Yi; Cui, Zhe

    2016-01-01

    Spectral optimization simulation of white light is studied to boost maximum attainable luminous efficacy of radiation at high color-rendering index (CRI) and various color temperatures. The photopic eye-sensitivity curve V(λ) is utilized as the dominant portion of white light spectra. Emission spectra of a blue InGaN light-emitting diode (LED) and a red AlInGaP LED are added to the spectrum of V(λ) to match white color coordinates. It is demonstrated that at the condition of color temperature from 2500 K to 6500 K and CRI above 90, such white sources can achieve spectral efficacy of 330–390 lm/W, which is higher than the previously reported theoretical maximum values. We show that this eye-sensitivity-based approach also has advantages on component energy conversion efficiency compared with previously reported optimization solutions

  2. Spectral signature barcodes based on S-shaped Split Ring Resonators (S-SRRs

    Directory of Open Access Journals (Sweden)

    Herrojo Cristian

    2016-01-01

    Full Text Available In this paper, it is shown that S-shaped split ring resonators (S-SRRs are useful particles for the implementation of spectral signature (i.e., a class of radiofrequency barcodes based on coplanar waveguide (CPW transmission lines loaded with such resonant elements. By virtue of its S shape, these resonators are electrically small. Hence S-SRRs are of interest for the miniaturization of the barcodes, since multiple resonators, each tuned at a different frequency, are used for encoding purposes. In particular, a 10-bit barcode occupying 1 GHz spectral bandwidth centered at 2.5 GHz, with dimensions of 9 cm2, is presented in this paper.

  3. Passive microrheology of soft materials with atomic force microscopy: A wavelet-based spectral analysis

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Torres, C.; Streppa, L. [CNRS, UMR5672, Laboratoire de Physique, Ecole Normale Supérieure de Lyon, 46 Allée d' Italie, Université de Lyon, 69007 Lyon (France); Arneodo, A.; Argoul, F. [CNRS, UMR5672, Laboratoire de Physique, Ecole Normale Supérieure de Lyon, 46 Allée d' Italie, Université de Lyon, 69007 Lyon (France); CNRS, UMR5798, Laboratoire Ondes et Matière d' Aquitaine, Université de Bordeaux, 351 Cours de la Libération, 33405 Talence (France); Argoul, P. [Université Paris-Est, Ecole des Ponts ParisTech, SDOA, MAST, IFSTTAR, 14-20 Bd Newton, Cité Descartes, 77420 Champs sur Marne (France)

    2016-01-18

    Compared to active microrheology where a known force or modulation is periodically imposed to a soft material, passive microrheology relies on the spectral analysis of the spontaneous motion of tracers inherent or external to the material. Passive microrheology studies of soft or living materials with atomic force microscopy (AFM) cantilever tips are rather rare because, in the spectral densities, the rheological response of the materials is hardly distinguishable from other sources of random or periodic perturbations. To circumvent this difficulty, we propose here a wavelet-based decomposition of AFM cantilever tip fluctuations and we show that when applying this multi-scale method to soft polymer layers and to living myoblasts, the structural damping exponents of these soft materials can be retrieved.

  4. Investigation of spectral characteristics of tunnel photodiodes based on DLC nanofilms

    Science.gov (United States)

    Akchurin, Garif G.; Aban'shin, Nickolay P.; Avetisyan, Yuri A.; Akchurin, Georgy G.; Kochubey, Vyacheslav I.; Yakunin, Alexander N.

    2018-04-01

    The tunneling photo effect has been studied in a microdiode with an electrostatic field localized at an emitter based on a nanosized DLC structure. It is established the photocurrent, when the carbon nanoemitter is exposed by laser and tunable low-coherent radiation in the spectral range from UV to near IR with photons of low energy (below work function). A linear dependence of the photocurrent on the level of optical power in the range of micro- and milliwatt power is established. The effect of saturation of the current-voltage characteristics of the tunnel photocurrent associated with a finite concentration of non-equilibrium photoelectrons is observed. The observed spectral Watt-Amper characteristics can be adequately interpreted using a modified Fowler-Nordheim equation for non-equilibrium photoelectrons.

  5. Pulsed photothermal profiling of water-based samples using a spectrally composite reconstruction approach

    International Nuclear Information System (INIS)

    Majaron, B; Milanic, M

    2010-01-01

    Pulsed photothermal profiling involves reconstruction of temperature depth profile induced in a layered sample by single-pulse laser exposure, based on transient change in mid-infrared (IR) emission from its surface. Earlier studies have indicated that in watery tissues, featuring a pronounced spectral variation of mid-IR absorption coefficient, analysis of broadband radiometric signals within the customary monochromatic approximation adversely affects profiling accuracy. We present here an experimental comparison of pulsed photothermal profiling in layered agar gel samples utilizing a spectrally composite kernel matrix vs. the customary approach. By utilizing a custom reconstruction code, the augmented approach reduces broadening of individual temperature peaks to 14% of the absorber depth, in contrast to 21% obtained with the customary approach.

  6. A REGION-BASED MULTI-SCALE APPROACH FOR OBJECT-BASED IMAGE ANALYSIS

    Directory of Open Access Journals (Sweden)

    T. Kavzoglu

    2016-06-01

    Full Text Available Within the last two decades, object-based image analysis (OBIA considering objects (i.e. groups of pixels instead of pixels has gained popularity and attracted increasing interest. The most important stage of the OBIA is image segmentation that groups spectrally similar adjacent pixels considering not only the spectral features but also spatial and textural features. Although there are several parameters (scale, shape, compactness and band weights to be set by the analyst, scale parameter stands out the most important parameter in segmentation process. Estimating optimal scale parameter is crucially important to increase the classification accuracy that depends on image resolution, image object size and characteristics of the study area. In this study, two scale-selection strategies were implemented in the image segmentation process using pan-sharped Qickbird-2 image. The first strategy estimates optimal scale parameters for the eight sub-regions. For this purpose, the local variance/rate of change (LV-RoC graphs produced by the ESP-2 tool were analysed to determine fine, moderate and coarse scales for each region. In the second strategy, the image was segmented using the three candidate scale values (fine, moderate, coarse determined from the LV-RoC graph calculated for whole image. The nearest neighbour classifier was applied in all segmentation experiments and equal number of pixels was randomly selected to calculate accuracy metrics (overall accuracy and kappa coefficient. Comparison of region-based and image-based segmentation was carried out on the classified images and found that region-based multi-scale OBIA produced significantly more accurate results than image-based single-scale OBIA. The difference in classification accuracy reached to 10% in terms of overall accuracy.

  7. Novel Base Station MIMO Antennas with Enhanced Spectral Efficiencies Using Angular Reuse

    Directory of Open Access Journals (Sweden)

    Miguel Mora-Andreu

    2015-01-01

    Full Text Available The true polarization diversity (TPD technique is combined with the spatial diversity technique in novel MIMO antenna array geometries with a large number of elements. The use of a large number of elements requires some angular reuse within the array for polarization diversity. With designs compatible with existing base station antenna array configurations, the novel geometries with combining diversity schemes are shown to be able to achieve near the maximum spectral efficiencies. True polarization diversity (TPD schemes are found to be an excellent complement to more conventional spatial diversity schemes for obtaining optimum MIMO array performance in base station antennas.

  8. Numerical solution of the unsteady diffusion-convection-reaction equation based on improved spectral Galerkin method

    Science.gov (United States)

    Zhong, Jiaqi; Zeng, Cheng; Yuan, Yupeng; Zhang, Yuzhe; Zhang, Ye

    2018-04-01

    The aim of this paper is to present an explicit numerical algorithm based on improved spectral Galerkin method for solving the unsteady diffusion-convection-reaction equation. The principal characteristics of this approach give the explicit eigenvalues and eigenvectors based on the time-space separation method and boundary condition analysis. With the help of Fourier series and Galerkin truncation, we can obtain the finite-dimensional ordinary differential equations which facilitate the system analysis and controller design. By comparing with the finite element method, the numerical solutions are demonstrated via two examples. It is shown that the proposed method is effective.

  9. Discriminative illumination: per-pixel classification of raw materials based on optimal projections of spectral BRDF.

    Science.gov (United States)

    Liu, Chao; Gu, Jinwei

    2014-01-01

    Classifying raw, unpainted materials--metal, plastic, ceramic, fabric, and so on--is an important yet challenging task for computer vision. Previous works measure subsets of surface spectral reflectance as features for classification. However, acquiring the full spectral reflectance is time consuming and error-prone. In this paper, we propose to use coded illumination to directly measure discriminative features for material classification. Optimal illumination patterns--which we call "discriminative illumination"--are learned from training samples, after projecting to which the spectral reflectance of different materials are maximally separated. This projection is automatically realized by the integration of incident light for surface reflection. While a single discriminative illumination is capable of linear, two-class classification, we show that multiple discriminative illuminations can be used for nonlinear and multiclass classification. We also show theoretically that the proposed method has higher signal-to-noise ratio than previous methods due to light multiplexing. Finally, we construct an LED-based multispectral dome and use the discriminative illumination method for classifying a variety of raw materials, including metal (aluminum, alloy, steel, stainless steel, brass, and copper), plastic, ceramic, fabric, and wood. Experimental results demonstrate its effectiveness.

  10. 3D anisotropic modeling and identification for airborne EM systems based on the spectral-element method

    Science.gov (United States)

    Huang, Xin; Yin, Chang-Chun; Cao, Xiao-Yue; Liu, Yun-He; Zhang, Bo; Cai, Jing

    2017-09-01

    The airborne electromagnetic (AEM) method has a high sampling rate and survey flexibility. However, traditional numerical modeling approaches must use high-resolution physical grids to guarantee modeling accuracy, especially for complex geological structures such as anisotropic earth. This can lead to huge computational costs. To solve this problem, we propose a spectral-element (SE) method for 3D AEM anisotropic modeling, which combines the advantages of spectral and finite-element methods. Thus, the SE method has accuracy as high as that of the spectral method and the ability to model complex geology inherited from the finite-element method. The SE method can improve the modeling accuracy within discrete grids and reduce the dependence of modeling results on the grids. This helps achieve high-accuracy anisotropic AEM modeling. We first introduced a rotating tensor of anisotropic conductivity to Maxwell's equations and described the electrical field via SE basis functions based on GLL interpolation polynomials. We used the Galerkin weighted residual method to establish the linear equation system for the SE method, and we took a vertical magnetic dipole as the transmission source for our AEM modeling. We then applied fourth-order SE calculations with coarse physical grids to check the accuracy of our modeling results against a 1D semi-analytical solution for an anisotropic half-space model and verified the high accuracy of the SE. Moreover, we conducted AEM modeling for different anisotropic 3D abnormal bodies using two physical grid scales and three orders of SE to obtain the convergence conditions for different anisotropic abnormal bodies. Finally, we studied the identification of anisotropy for single anisotropic abnormal bodies, anisotropic surrounding rock, and single anisotropic abnormal body embedded in an anisotropic surrounding rock. This approach will play a key role in the inversion and interpretation of AEM data collected in regions with anisotropic

  11. Spectral-analysis-based extraction of land disturbances arising from oil and gas development in diverse landscapes

    Science.gov (United States)

    Zhang, Ying; Lantz, Nicholas; Guindon, Bert; Jiao, Xianfen

    2017-01-01

    Accurate and frequent monitoring of land surface changes arising from oil and gas exploration and extraction is a key requirement for the responsible and sustainable development of these resources. Petroleum deposits typically extend over large geographic regions but much of the infrastructure required for oil and gas recovery takes the form of numerous small-scale features (e.g., well sites, access roads, etc.) scattered over the landscape. Increasing exploitation of oil and gas deposits will increase the presence of these disturbances in heavily populated regions. An object-based approach is proposed to utilize RapidEye satellite imagery to delineate well sites and related access roads in diverse complex landscapes, where land surface changes also arise from other human activities, such as forest logging and agriculture. A simplified object-based change vector approach, adaptable to operational use, is introduced to identify the disturbances on land based on red-green spectral response and spatial attributes of candidate object size and proximity to roads. Testing of the techniques has been undertaken with RapidEye multitemporal imagery in two test sites located at Alberta, Canada: one was a predominant natural forest landscape and the other landscape dominated by intensive agricultural activities. Accuracies of 84% and 73%, respectively, have been achieved for the identification of well site and access road infrastructure of the two sites based on fully automated processing. Limited manual relabeling of selected image segments can improve these accuracies to 95%.

  12. A New Pansharpening Method Based on Spatial and Spectral Sparsity Priors.

    Science.gov (United States)

    He, Xiyan; Condat, Laurent; Bioucas-Diaz, Jose; Chanussot, Jocelyn; Xia, Junshi

    2014-06-27

    The development of multisensor systems in recent years has led to great increase in the amount of available remote sensing data. Image fusion techniques aim at inferring high quality images of a given area from degraded versions of the same area obtained by multiple sensors. This paper focuses on pansharpening, which is the inference of a high spatial resolution multispectral image from two degraded versions with complementary spectral and spatial resolution characteristics: a) a low spatial resolution multispectral image; and b) a high spatial resolution panchromatic image. We introduce a new variational model based on spatial and spectral sparsity priors for the fusion. In the spectral domain we encourage low-rank structure, whereas in the spatial domain we promote sparsity on the local differences. Given the fact that both panchromatic and multispectral images are integrations of the underlying continuous spectra using different channel responses, we propose to exploit appropriate regularizations based on both spatial and spectral links between panchromatic and the fused multispectral images. A weighted version of the vector Total Variation (TV) norm of the data matrix is employed to align the spatial information of the fused image with that of the panchromatic image. With regard to spectral information, two different types of regularization are proposed to promote a soft constraint on the linear dependence between the panchromatic and the fused multispectral images. The first one estimates directly the linear coefficients from the observed panchromatic and low resolution multispectral images by Linear Regression (LR) while the second one employs the Principal Component Pursuit (PCP) to obtain a robust recovery of the underlying low-rank structure. We also show that the two regularizers are strongly related. The basic idea of both regularizers is that the fused image should have low-rank and preserve edge locations. We use a variation of the recently proposed

  13. Structural and spectral comparisons between isomeric benzisothiazole and benzothiazole based aromatic heterocyclic dyes

    Science.gov (United States)

    Wang, Yin-Ge; Wang, Yue-Hua; Tao, Tao; Qian, Hui-Fen; Huang, Wei

    2015-09-01

    A pair of isomeric heterocyclic compounds, namely 3-amino-5-nitro-[2,1]-benzisothiazole and 2-amino-6-nitrobenzothiazole, are used as the diazonium components to couple with two N-substituted 4-aminobenzene derivatives. As a result, two pairs of isomeric aromatic heterocyclic azo dyes have been produced and they are structurally and spectrally characterized and compared including single-crystal structures, electronic spectra, solvatochromism and reversible acid-base discoloration, thermal stability and theoretically calculations. It is concluded that both benzisothiazole and benzothiazole based dyes show planar molecular structures and offset π-π stacking interactions, solvatochromism and reversible acid-base discoloration. Furthermore, benzisothiazole based aromatic heterocyclic dyes exhibit higher thermal stability, larger solvatochromic effects and maximum absorption wavelengths than corresponding benzothiazole based ones, which can be explained successfully by the differences of their calculated isomerization energy, dipole moment and molecular band gaps.

  14. Analytic models of spectral responses of fiber-grating-based interferometers on FMC theory.

    Science.gov (United States)

    Zeng, Xiangkai; Wei, Lai; Pan, Yingjun; Liu, Shengping; Shi, Xiaohui

    2012-02-13

    In this paper the analytic models (AMs) of the spectral responses of fiber-grating-based interferometers are derived from the Fourier mode coupling (FMC) theory proposed recently. The interferometers include Fabry-Perot cavity, Mach-Zehnder and Michelson interferometers, which are constructed by uniform fiber Bragg gratings and long-period fiber gratings, and also by Gaussian-apodized ones. The calculated spectra based on the analytic models are achieved, and compared with the measured cases and those on the transfer matrix (TM) method. The calculations and comparisons have confirmed that the AM-based spectrum is in excellent agreement with the TM-based one and the measured case, of which the efficiency is improved up to ~2990 times that of the TM method for non-uniform-grating-based in-fiber interferometers.

  15. ETA CARINAE ACROSS THE 2003.5 MINIMUM: ANALYSIS IN THE VISIBLE AND NEAR-INFRARED SPECTRAL REGION

    International Nuclear Information System (INIS)

    Nielsen, K. E.; Kober, G. Vieira; Weis, K.; Bomans, D. J.; Gull, T. R.; Stahl, O.

    2009-01-01

    We present an analysis of the visible through near-infrared spectrum of Eta Carinae (η Car) and its ejecta obtained during the 'η Car Campaign with the Ultraviolet and Visual Echelle Spectrograph (UVES) at the ESO Very Large Telescope (VLT)'. This is a part of larger effort to present a complete η Car spectrum, and extends the previously presented analyses with the Hubble Space Telescope/Space Telescope Imaging Spectrograph (HST/STIS) in the UV (1240-3159 A) to 10,430 A. The spectrum in the mid- and near-UV is characterized by the ejecta absorption. At longer wavelengths, stellar wind features from the central source and narrow-emission lines from the Weigelt condensations dominate the spectrum. However, narrow absorption lines from the circumstellar shells are present. This paper provides a description of the spectrum between 3060 and 10,430 A, including line identifications of the ejecta absorption spectrum, the emission spectrum from the Weigelt condensations and the P Cygni stellar wind features. The high spectral resolving power of VLT/UVES enables equivalent width measurements of atomic and molecular absorption lines for elements with no transitions at the shorter wavelengths. However, the ground-based seeing and contributions of nebular-scattered radiation prevent direct comparison of measured equivalent widths in the VLT/UVES and HST/STIS spectra. Fortunately, HST/STIS and VLT/UVES have a small overlap in wavelength coverage which allows us to compare and adjust for the difference in scattered radiation entering the instruments' apertures. This paper provides a complete online VLT/UVES spectrum with line identifications and a spectral comparison between HST/STIS and VLT/UVES between 3060 and 3160 A.

  16. Analysis of dust and marine aerosol optical depth spectral-curvature information in the UV to SWIR (Short Wave Infrared) wavelength regions.

    Science.gov (United States)

    O'Neill, N. T.; Smirnov, A.; Eck, T. F.; Sakerin, S.; Kabanov, D.

    2005-12-01

    Traditional sunphotometry in the UV, visible and very NIR (Near Infrared) spectral regions is weighted, in terms of spectral information content, towards sub-micron (fine mode) particles. Sunphotometry in the NIR and SWIR increases the diversity and information content of spectral aerosol optical depth (AOD) measurements for supermicron (coarse mode) particles. Two data sets representing dust aerosols from the UAE (United Arab Emirates) region and marine aerosols from the northern, tropical and southern Atlantic Ocean were analyzed in terms of their spectral curvature diversity and information content. The former data set was acquired using NIR-enhanced CIMEL sunphotometers (340, 340, 380, 440, 500, 670, 870, 1020, 1640 nm) as part of the August to October, 2004 UAE2 field campaign while the latter data set was acquired using an automated Russian UV to SWIR SP-5 sunphotometer (339, 423, 438, 484, 552, 633, 677, 777, 869, 1241, 1560, 2148, 4000 nm) as part of a October/December 2004 cruise campaign in the northern, tropical and south Atlantic Ocean. A Microtops hand-held sunphotometer was also employed to acquire VIS to NIR AOD spectra during the latter field campaign. Results will be presented in terms of robust micro-physical and spectral curvature parameters which characterize super-micron aerosols and, in a more general sense, in terms of what universal/fundamental optical inferences can be drawn from the two disperse data sets.

  17. Physical and chemical differentiation of the luminous star-forming region W49A. Results from the JCMT Spectral Legacy Survey

    Science.gov (United States)

    Nagy, Z.; van der Tak, F. F. S.; Fuller, G. A.; Plume, R.

    2015-05-01

    Context. The massive and luminous star-forming region W49A is a well-known Galactic candidate to probe the physical conditions and chemistry similar to those expected in external starburst galaxies. Aims: We aim to probe the physical and chemical structure of W49A on a spatial scale of ~0.8 pc based on the JCMT Spectral Legacy Survey, which covers the frequency range between 330 and 373 GHz. Methods: The wide 2 × 2 arcmin field and the high spectral resolution of the HARP instrument on JCMT provides information on the spatial structure and kinematics of the cloud traced by the observed molecular lines. For species where multiple transitions are available, we estimate excitation temperatures and column densities using a population diagram method that takes beam dilution and optical depth corrections into account. Results: We detected 255 transitions corresponding to 63 species in the 330-373 GHz range at the center position of W49A. Excitation conditions can be probed for 14 molecules, including the complex organic molecules CH3CCH, CH3CN, and CH3OH. The chemical composition suggests the importance of shock, photon-dominated region (PDR), and hot core chemistry. Many molecular lines show a significant spatial extent across the maps including CO and its isotopologues, high density tracers (e.g., HCN, HNC, CS, HCO+), and tracers of UV irradiation (e.g., CN and C2H). The spatially extended species reveal a complex velocity-structure of W49A with possible infall and outflow motions. Large variations are seen between the subregions with mostly blue-shifted emission toward the eastern tail, mostly red-shifted emission toward the northern clump, and emission peaking around the expected source velocity toward the southwest clump. Conclusions: A comparison of column density ratios of characteristic species observed toward W49A to Galactic PDRs suggests that while the chemistry toward the W49A center is driven by a combination of UV irradiation and shocks, UV irradiation

  18. An optical modulation format generation scheme based on spectral filtering and frequency-to-time mapping

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ai-ling; ZHANG Yue; SONG Hong-yun; YAO Yuan; PAN Hong-gang

    2018-01-01

    An optical modulation format generation scheme based on spectral filtering and frequency-to-time mapping is experimentally demonstrated.Many modulation formats with continuously adjustable duty radio and bit rate can be formed by changing the dispersion of dispersion element and the bandwidth of shaped spectrum in this scheme.In the experiment,non-return-to-zero (NRZ) signal with bit rate of 29.41 Gbit/s and 1/2 duty ratio return-to-zero (RZ) signal with bit rate of 13.51 Gbit/s are obtained.The maximum bit rate of modulation format signal is also analyzed.

  19. Multi-spectral quantitative phase imaging based on filtration of light via ultrasonic wave

    Science.gov (United States)

    Machikhin, A. S.; Polschikova, O. V.; Ramazanova, A. G.; Pozhar, V. E.

    2017-07-01

    A new digital holographic microscopy scheme for multi-spectral quantitative phase imaging is proposed and implemented. It is based on acousto-optic filtration of wide-band low-coherence light at the entrance of a Mach-Zehnder interferometer, recording and digital processing of interferograms. The key requirements for the acousto-optic filter are discussed. The effectiveness of the technique is demonstrated by calculating the phase maps of human red blood cells at multiple wavelengths in the range 770-810 nm. The scheme can be used for the measurement of dispersion of thin films and biological samples.

  20. Time lens based optical fourier transformation for advanced processing of spectrally-efficient OFDM and N-WDM signals

    DEFF Research Database (Denmark)

    Guan, Pengyu; Røge, Kasper Meldgaard; Morioka, Toshio

    2016-01-01

    We review recent progress in the use of time lens based optical Fourier transformation for advanced optical signal processing, with focus on all-optical generation, detection and format conversion of spectrally-efficient OFDM and N-WDM signals.......We review recent progress in the use of time lens based optical Fourier transformation for advanced optical signal processing, with focus on all-optical generation, detection and format conversion of spectrally-efficient OFDM and N-WDM signals....

  1. A method of incident angle estimation for high resolution spectral recovery in filter-array-based spectrometers

    Science.gov (United States)

    Kim, Cheolsun; Lee, Woong-Bi; Ju, Gun Wu; Cho, Jeonghoon; Kim, Seongmin; Oh, Jinkyung; Lim, Dongsung; Lee, Yong Tak; Lee, Heung-No

    2017-02-01

    In recent years, there has been an increasing interest in miniature spectrometers for research and development. Especially, filter-array-based spectrometers have advantages of low cost and portability, and can be applied in various fields such as biology, chemistry and food industry. Miniaturization in optical filters causes degradation of spectral resolution due to limitations on spectral responses and the number of filters. Nowadays, many studies have been reported that the filter-array-based spectrometers have achieved resolution improvements by using digital signal processing (DSP) techniques. The performance of the DSP-based spectral recovery highly depends on the prior information of transmission functions (TFs) of the filters. The TFs vary with respect to an incident angle of light onto the filter-array. Conventionally, it is assumed that the incident angle of light on the filters is fixed and the TFs are known to the DSP. However, the incident angle is inconstant according to various environments and applications, and thus TFs also vary, which leads to performance degradation of spectral recovery. In this paper, we propose a method of incident angle estimation (IAE) for high resolution spectral recovery in the filter-array-based spectrometers. By exploiting sparse signal reconstruction of the L1- norm minimization, IAE estimates an incident angle among all possible incident angles which minimizes the error of the reconstructed signal. Based on IAE, DSP effectively provides a high resolution spectral recovery in the filter-array-based spectrometers.

  2. Vegetation species composition and canopy architecture information expressed in leaf water absorption measured in the 1000 nm and 2200 spectral region by an imaging spectrometer

    Science.gov (United States)

    Green, Robert O.; Roberts, Dar A.

    1995-01-01

    Plant species composition and plant architectural attributes are critical parameters required for the measuring, monitoring, and modeling of terrestrial ecosystems. Remote sensing is commonly cited as an important tool for deriving vegetation properties at an appropriate scale for ecosystem studies, ranging from local to regional and even synoptic scales. Classical approaches rely on vegetation indices such as the normalized difference vegetation index (NDVI) to estimate biophysical parameters such as leaf area index or intercepted photosynthetically active radiation (IPAR). Another approach is to apply a variety of classification schemes to map vegetation and thus extrapolate fine-scale information about specific sites to larger areas of similar composition. Imaging spectrometry provides additional information that is not obtainable through broad-band sensors and that may provide improved inputs both to direct biophysical estimates as well as classification schemes. Some of this capability has been demonstrated through improved discrimination of vegetation, estimates of canopy biochemistry, and liquid water estimates from vegetation. We investigate further the potential of leaf water absorption estimated from Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) data as a means for discriminating vegetation types and deriving canopy architectural information. We expand our analysis to incorporate liquid water estimates from two spectral regions, the 1000-nm region and the 2200-nm region. The study was conducted in the vicinity of Jasper Ridge, California, which is located on the San Francisco peninsula to the west of the Stanford University campus. AVIRIS data were acquired over Jasper Ridge, CA, on June 2, 1992, at 19:31 UTC. Spectra from three sites in this image were analyzed. These data are from an area of healthy grass, oak woodland, and redwood forest, respectively. For these analyses, the AVIRIS-measured upwelling radiance spectra for the entire Jasper

  3. Emission spectral analysis of nickel-base superalloys with fixed time intergration technique

    International Nuclear Information System (INIS)

    Okochi, Haruno; Takahashi, Katsuyuki; Suzuki, Shunichi; Sudo, Emiko

    1980-01-01

    Simultaneous determination of multielements (C, B, Mo, Ta, Co, Fe, Mn, Cr, Nb, Cu, Ti, Zr, and Al) in nickel-base superalloys (Ni: 68 -- 76%) was performed by emission spectral analysis. At first, samples which had various nickel contents (ni: 68 -- 76%) were prepared by using JAERI R9, nickel and other metals (Fe, Co, or Cr). It was confirmed that in the internal standard method (Ni II 227.73 nm), analytical values of all the elements examined decreased with a decrease of the integration time (ca. 3.9 -- 4.6 s), that is, an increase of the nickel content. On the other hand, according to the fixed time integration method, elements except for C, Mo, and Cr were not interfered within the range of nickel contents examined. A series of nickel-base binary alloys (Al, Si, Ti, Cr, Mn, Fe, Co, Nb, Mo, and W series) were prepared by high frequency induction melting and the centrifugal casting method and formulae for correcting interferences with near spectral lines were obtained. Various synthetic samples were prepared and analysed by this method. The equations of calibration curves were derived from the data for standard samples (JAERI R1 -- R6, NBS 1189, 1203 -- 1205, and B.S. 600B) by curve fitting with orthogonal polynomials using a computer. For the assessment of this method studied, the F-test was performed by comparison of variances of both analytical values of standard and synthetic samples. The surfaces of specimens were polished with a belt grinder using No. 80 of alumina or silicon carbide endless-paper. The preburn period and integration one were decided at 5 and 6 s respectively. A few standard samples which gave worse reproducibility in emission spectral analysis was investigated with an optical microscope and an electron probe X-ray microanalyser. (author)

  4. ℓ0 -based sparse hyperspectral unmixing using spectral information and a multi-objectives formulation

    Science.gov (United States)

    Xu, Xia; Shi, Zhenwei; Pan, Bin

    2018-07-01

    Sparse unmixing aims at recovering pure materials from hyperpspectral images and estimating their abundance fractions. Sparse unmixing is actually ℓ0 problem which is NP-h ard, and a relaxation is often used. In this paper, we attempt to deal with ℓ0 problem directly via a multi-objective based method, which is a non-convex manner. The characteristics of hyperspectral images are integrated into the proposed method, which leads to a new spectra and multi-objective based sparse unmixing method (SMoSU). In order to solve the ℓ0 norm optimization problem, the spectral library is encoded in a binary vector, and a bit-wise flipping strategy is used to generate new individuals in the evolution process. However, a multi-objective method usually produces a number of non-dominated solutions, while sparse unmixing requires a single solution. How to make the final decision for sparse unmixing is challenging. To handle this problem, we integrate the spectral characteristic of hyperspectral images into SMoSU. By considering the spectral correlation in hyperspectral data, we improve the Tchebycheff decomposition function in SMoSU via a new regularization item. This regularization item is able to enforce the individual divergence in the evolution process of SMoSU. In this way, the diversity and convergence of population is further balanced, which is beneficial to the concentration of individuals. In the experiments part, three synthetic datasets and one real-world data are used to analyse the effectiveness of SMoSU, and several state-of-art sparse unmixing algorithms are compared.

  5. Extraction and prediction of indices for monsoon intraseasonal oscillations: an approach based on nonlinear Laplacian spectral analysis

    Science.gov (United States)

    Sabeerali, C. T.; Ajayamohan, R. S.; Giannakis, Dimitrios; Majda, Andrew J.

    2017-11-01

    An improved index for real-time monitoring and forecast verification of monsoon intraseasonal oscillations (MISOs) is introduced using the recently developed nonlinear Laplacian spectral analysis (NLSA) technique. Using NLSA, a hierarchy of Laplace-Beltrami (LB) eigenfunctions are extracted from unfiltered daily rainfall data from the Global Precipitation Climatology Project over the south Asian monsoon region. Two modes representing the full life cycle of the northeastward-propagating boreal summer MISO are identified from the hierarchy of LB eigenfunctions. These modes have a number of advantages over MISO modes extracted via extended empirical orthogonal function analysis including higher memory and predictability, stronger amplitude and higher fractional explained variance over the western Pacific, Western Ghats, and adjoining Arabian Sea regions, and more realistic representation of the regional heat sources over the Indian and Pacific Oceans. Real-time prediction of NLSA-derived MISO indices is demonstrated via extended-range hindcasts based on NCEP Coupled Forecast System version 2 operational output. It is shown that in these hindcasts the NLSA MISO indices remain predictable out to ˜3 weeks.

  6. Object-based landslide detection in different geographic regions

    Science.gov (United States)

    Friedl, Barbara; Hölbling, Daniel; Eisank, Clemens; Blaschke, Thomas

    2015-04-01

    Landslides occur in almost all mountainous regions of the world and rank among the most severe natural hazards. In the last decade - according to the world disaster report 2014 published by the International Federation of Red Cross and Red Crescent Societies (IRFC) - more than 9.000 people were killed by mass movements, more than 3.2 million people were affected and the total amount of disaster estimated damage accounts to more than 1.700 million US dollars. The application of remote sensing data for mapping landslides can contribute to post-disaster reconstruction or hazard mitigation, either by providing rapid information about the spatial distribution and location of landslides in the aftermath of triggering events or by creating and updating landslide inventories. This is especially valid for remote and inaccessible areas, where information on landslides is often lacking. However, reliable methods are needed for extracting timely and relevant information about landslides from remote sensing data. In recent years, novel methods such as object-based image analysis (OBIA) have been successfully employed for semi-automated landslide mapping. Several studies revealed that OBIA frequently outperforms pixel-based approaches, as a range of image object properties (spectral, spatial, morphometric, contextual) can be exploited during the analysis. However, object-based methods are often tailored to specific study areas, and thus, the transferability to regions with different geological settings, is often limited. The present case study evaluates the transferability and applicability of an OBIA approach for landslide detection in two distinct regions, i.e. the island of Taiwan and Austria. In Taiwan, sub-areas in the Baichi catchment in the North and in the Huaguoshan catchment in the southern-central part of the island are selected; in Austria, landslide-affected sites in the Upper Salzach catchment in the federal state of Salzburg are investigated. For both regions

  7. Image-Based Airborne Sensors: A Combined Approach for Spectral Signatures Classification through Deterministic Simulated Annealing

    Science.gov (United States)

    Guijarro, María; Pajares, Gonzalo; Herrera, P. Javier

    2009-01-01

    The increasing technology of high-resolution image airborne sensors, including those on board Unmanned Aerial Vehicles, demands automatic solutions for processing, either on-line or off-line, the huge amountds of image data sensed during the flights. The classification of natural spectral signatures in images is one potential application. The actual tendency in classification is oriented towards the combination of simple classifiers. In this paper we propose a combined strategy based on the Deterministic Simulated Annealing (DSA) framework. The simple classifiers used are the well tested supervised parametric Bayesian estimator and the Fuzzy Clustering. The DSA is an optimization approach, which minimizes an energy function. The main contribution of DSA is its ability to avoid local minima during the optimization process thanks to the annealing scheme. It outperforms simple classifiers used for the combination and some combined strategies, including a scheme based on the fuzzy cognitive maps and an optimization approach based on the Hopfield neural network paradigm. PMID:22399989

  8. On the gain properties of “thin” elastically strained InGaAs/InGaAlAs quantum wells emitting in the near-infrared spectral region near 1550 nm

    Energy Technology Data Exchange (ETDEWEB)

    Novikov, I. I.; Karachinsky, L. Ya. [Connector Optics LLC (Russian Federation); Kolodeznyi, E. S.; Bougrov, V. E. [National Research University of Information Technologies, Mechanics and Optics (Russian Federation); Kurochkin, A. S.; Gladyshev, A. G.; Babichev, A. V. [Connector Optics LLC (Russian Federation); Gadzhiev, I. M.; Buyalo, M. S. [National Research University of Information Technologies, Mechanics and Optics (Russian Federation); Zadiranov, Yu. M.; Usikova, A. A., E-mail: anton@beam.ioffe.ru; Shernyakov, Yu. M. [Russian Academy of Sciences, Ioffe Physical–Technical Institute (Russian Federation); Savelyev, A. V.; Nyapshaev, I. A. [National Research University of Information Technologies, Mechanics and Optics (Russian Federation); Egorov, A. Yu. [Connector Optics LLC (Russian Federation)

    2016-10-15

    The results of experimental studies of the gain properties of “thin” (3.2 nm thick) elastically strained InGaAs/InGaAlAs quantum wells emitting in the near-infrared spectral region near 1550 nm are presented. The results of studying the threshold and gain characteristics of stripe laser diodes with active regions based on “thin” quantum wells with a lattice–substrate mismatch of +1.0% show that the quantum wells under study exhibit a high modal gain of 11 cm{sup –1} and a low transparency current density of 46 A/cm{sup 2} per quantum well.

  9. Airborne relay-based regional positioning system.

    Science.gov (United States)

    Lee, Kyuman; Noh, Hongjun; Lim, Jaesung

    2015-05-28

    Ground-based pseudolite systems have some limitations, such as low vertical accuracy, multipath effects and near-far problems. These problems are not significant in airborne-based pseudolite systems. However, the monitoring of pseudolite positions is required because of the mobility of the platforms on which the pseudolites are mounted, and this causes performance degradation. To address these pseudolite system limitations, we propose an airborne relay-based regional positioning system that consists of a master station, reference stations, airborne relays and a user. In the proposed system, navigation signals are generated from the reference stations located on the ground and are relayed via the airborne relays. Unlike in conventional airborne-based systems, the user in the proposed system sequentially estimates both the locations of airborne relays and his/her own position. Therefore, a delay due to monitoring does not occur, and the accuracy is not affected by the movement of airborne relays. We conducted several simulations to evaluate the performance of the proposed system. Based on the simulation results, we demonstrated that the proposed system guarantees a higher accuracy than airborne-based pseudolite systems, and it is feasible despite the existence of clock offsets among reference stations.

  10. Global contrast based salient region detection

    KAUST Repository

    Cheng, Ming-Ming

    2011-08-25

    Reliable estimation of visual saliency allows appropriate processing of images without prior knowledge of their contents, and thus remains an important step in many computer vision tasks including image segmentation, object recognition, and adaptive compression. We propose a regional contrast based saliency extraction algorithm, which simultaneously evaluates global contrast differences and spatial coherence. The proposed algorithm is simple, efficient, and yields full resolution saliency maps. Our algorithm consistently outperformed existing saliency detection methods, yielding higher precision and better recall rates, when evaluated using one of the largest publicly available data sets. We also demonstrate how the extracted saliency map can be used to create high quality segmentation masks for subsequent image processing.

  11. Global contrast based salient region detection

    KAUST Repository

    Cheng, Ming-Ming; Zhang, Guo-Xin; Mitra, Niloy J.; Huang, Xiaolei; Hu, Shi-Min

    2011-01-01

    Reliable estimation of visual saliency allows appropriate processing of images without prior knowledge of their contents, and thus remains an important step in many computer vision tasks including image segmentation, object recognition, and adaptive compression. We propose a regional contrast based saliency extraction algorithm, which simultaneously evaluates global contrast differences and spatial coherence. The proposed algorithm is simple, efficient, and yields full resolution saliency maps. Our algorithm consistently outperformed existing saliency detection methods, yielding higher precision and better recall rates, when evaluated using one of the largest publicly available data sets. We also demonstrate how the extracted saliency map can be used to create high quality segmentation masks for subsequent image processing.

  12. SVM-Based Spectral Analysis for Heart Rate from Multi-Channel WPPG Sensor Signals.

    Science.gov (United States)

    Xiong, Jiping; Cai, Lisang; Wang, Fei; He, Xiaowei

    2017-03-03

    Although wrist-type photoplethysmographic (hereafter referred to as WPPG) sensor signals can measure heart rate quite conveniently, the subjects' hand movements can cause strong motion artifacts, and then the motion artifacts will heavily contaminate WPPG signals. Hence, it is challenging for us to accurately estimate heart rate from WPPG signals during intense physical activities. The WWPG method has attracted more attention thanks to the popularity of wrist-worn wearable devices. In this paper, a mixed approach called Mix-SVM is proposed, it can use multi-channel WPPG sensor signals and simultaneous acceleration signals to measurement heart rate. Firstly, we combine the principle component analysis and adaptive filter to remove a part of the motion artifacts. Due to the strong relativity between motion artifacts and acceleration signals, the further denoising problem is regarded as a sparse signals reconstruction problem. Then, we use a spectrum subtraction method to eliminate motion artifacts effectively. Finally, the spectral peak corresponding to heart rate is sought by an SVM-based spectral analysis method. Through the public PPG database in the 2015 IEEE Signal Processing Cup, we acquire the experimental results, i.e., the average absolute error was 1.01 beat per minute, and the Pearson correlation was 0.9972. These results also confirm that the proposed Mix-SVM approach has potential for multi-channel WPPG-based heart rate estimation in the presence of intense physical exercise.

  13. SVM-Based Spectral Analysis for Heart Rate from Multi-Channel WPPG Sensor Signals

    Directory of Open Access Journals (Sweden)

    Jiping Xiong

    2017-03-01

    Full Text Available Although wrist-type photoplethysmographic (hereafter referred to as WPPG sensor signals can measure heart rate quite conveniently, the subjects’ hand movements can cause strong motion artifacts, and then the motion artifacts will heavily contaminate WPPG signals. Hence, it is challenging for us to accurately estimate heart rate from WPPG signals during intense physical activities. The WWPG method has attracted more attention thanks to the popularity of wrist-worn wearable devices. In this paper, a mixed approach called Mix-SVM is proposed, it can use multi-channel WPPG sensor signals and simultaneous acceleration signals to measurement heart rate. Firstly, we combine the principle component analysis and adaptive filter to remove a part of the motion artifacts. Due to the strong relativity between motion artifacts and acceleration signals, the further denoising problem is regarded as a sparse signals reconstruction problem. Then, we use a spectrum subtraction method to eliminate motion artifacts effectively. Finally, the spectral peak corresponding to heart rate is sought by an SVM-based spectral analysis method. Through the public PPG database in the 2015 IEEE Signal Processing Cup, we acquire the experimental results, i.e., the average absolute error was 1.01 beat per minute, and the Pearson correlation was 0.9972. These results also confirm that the proposed Mix-SVM approach has potential for multi-channel WPPG-based heart rate estimation in the presence of intense physical exercise.

  14. Separate photosensitizers mediate degradation of the 32-kDa photosystem II reaction center protein in the visible and UV spectral regions

    International Nuclear Information System (INIS)

    Greenberg, B.M.; Gaba, V.; Canaani, O.; Malkin, S.; Mattoo, A.K.; Edelman, M.

    1989-01-01

    A component of the photosystem II reaction center, the 32-kDa protein, is rapidly turned over in the light. The mechanism of its light-dependent metabolism is largely unknown. We quantified the rate of 32-kDa protein degradation over a broad spectral range (UV, visible, and far red). The quantum yield for degradation was highest in the UVB (280-320 nm) region. Spectral evidence demonstrates two distinctly different photosensitizers for 32-kDa protein degradation. The data implicate the bulk photosynthetic pigments (primarily chlorophyll) in the visible and far red regions, and plastoquinone (in one or more of its redox states) in the UV region. A significant portion of 32-kDa protein degradation in sunlight is attributed to UVB irradiance

  15. Spectral BRDF-based determination of proper measurement geometries to characterize color shift of special effect coatings.

    Science.gov (United States)

    Ferrero, Alejandro; Rabal, Ana; Campos, Joaquín; Martínez-Verdú, Francisco; Chorro, Elísabet; Perales, Esther; Pons, Alicia; Hernanz, María Luisa

    2013-02-01

    A reduced set of measurement geometries allows the spectral reflectance of special effect coatings to be predicted for any other geometry. A physical model based on flake-related parameters has been used to determine nonredundant measurement geometries for the complete description of the spectral bidirectional reflectance distribution function (BRDF). The analysis of experimental spectral BRDF was carried out by means of principal component analysis. From this analysis, a set of nine measurement geometries was proposed to characterize special effect coatings. It was shown that, for two different special effect coatings, these geometries provide a good prediction of their complete color shift.

  16. Application of Adjoint Method and Spectral-Element Method to Tomographic Inversion of Regional Seismological Structure Beneath Japanese Islands

    Science.gov (United States)

    Tsuboi, S.; Miyoshi, T.; Obayashi, M.; Tono, Y.; Ando, K.

    2014-12-01

    Recent progress in large scale computing by using waveform modeling technique and high performance computing facility has demonstrated possibilities to perform full-waveform inversion of three dimensional (3D) seismological structure inside the Earth. We apply the adjoint method (Liu and Tromp, 2006) to obtain 3D structure beneath Japanese Islands. First we implemented Spectral-Element Method to K-computer in Kobe, Japan. We have optimized SPECFEM3D_GLOBE (Komatitsch and Tromp, 2002) by using OpenMP so that the code fits hybrid architecture of K-computer. Now we could use 82,134 nodes of K-computer (657,072 cores) to compute synthetic waveform with about 1 sec accuracy for realistic 3D Earth model and its performance was 1.2 PFLOPS. We use this optimized SPECFEM3D_GLOBE code and take one chunk around Japanese Islands from global mesh and compute synthetic seismograms with accuracy of about 10 second. We use GAP-P2 mantle tomography model (Obayashi et al., 2009) as an initial 3D model and use as many broadband seismic stations available in this region as possible to perform inversion. We then use the time windows for body waves and surface waves to compute adjoint sources and calculate adjoint kernels for seismic structure. We have performed several iteration and obtained improved 3D structure beneath Japanese Islands. The result demonstrates that waveform misfits between observed and theoretical seismograms improves as the iteration proceeds. We now prepare to use much shorter period in our synthetic waveform computation and try to obtain seismic structure for basin scale model, such as Kanto basin, where there are dense seismic network and high seismic activity. Acknowledgements: This research was partly supported by MEXT Strategic Program for Innovative Research. We used F-net seismograms of the National Research Institute for Earth Science and Disaster Prevention.

  17. An adaptive demodulation approach for bearing fault detection based on adaptive wavelet filtering and spectral subtraction

    Science.gov (United States)

    Zhang, Yan; Tang, Baoping; Liu, Ziran; Chen, Rengxiang

    2016-02-01

    Fault diagnosis of rolling element bearings is important for improving mechanical system reliability and performance. Vibration signals contain a wealth of complex information useful for state monitoring and fault diagnosis. However, any fault-related impulses in the original signal are often severely tainted by various noises and the interfering vibrations caused by other machine elements. Narrow-band amplitude demodulation has been an effective technique to detect bearing faults by identifying bearing fault characteristic frequencies. To achieve this, the key step is to remove the corrupting noise and interference, and to enhance the weak signatures of the bearing fault. In this paper, a new method based on adaptive wavelet filtering and spectral subtraction is proposed for fault diagnosis in bearings. First, to eliminate the frequency associated with interfering vibrations, the vibration signal is bandpass filtered with a Morlet wavelet filter whose parameters (i.e. center frequency and bandwidth) are selected in separate steps. An alternative and efficient method of determining the center frequency is proposed that utilizes the statistical information contained in the production functions (PFs). The bandwidth parameter is optimized using a local ‘greedy’ scheme along with Shannon wavelet entropy criterion. Then, to further reduce the residual in-band noise in the filtered signal, a spectral subtraction procedure is elaborated after wavelet filtering. Instead of resorting to a reference signal as in the majority of papers in the literature, the new method estimates the power spectral density of the in-band noise from the associated PF. The effectiveness of the proposed method is validated using simulated data, test rig data, and vibration data recorded from the transmission system of a helicopter. The experimental results and comparisons with other methods indicate that the proposed method is an effective approach to detecting the fault-related impulses

  18. An adaptive demodulation approach for bearing fault detection based on adaptive wavelet filtering and spectral subtraction

    International Nuclear Information System (INIS)

    Zhang, Yan; Tang, Baoping; Chen, Rengxiang; Liu, Ziran

    2016-01-01

    Fault diagnosis of rolling element bearings is important for improving mechanical system reliability and performance. Vibration signals contain a wealth of complex information useful for state monitoring and fault diagnosis. However, any fault-related impulses in the original signal are often severely tainted by various noises and the interfering vibrations caused by other machine elements. Narrow-band amplitude demodulation has been an effective technique to detect bearing faults by identifying bearing fault characteristic frequencies. To achieve this, the key step is to remove the corrupting noise and interference, and to enhance the weak signatures of the bearing fault. In this paper, a new method based on adaptive wavelet filtering and spectral subtraction is proposed for fault diagnosis in bearings. First, to eliminate the frequency associated with interfering vibrations, the vibration signal is bandpass filtered with a Morlet wavelet filter whose parameters (i.e. center frequency and bandwidth) are selected in separate steps. An alternative and efficient method of determining the center frequency is proposed that utilizes the statistical information contained in the production functions (PFs). The bandwidth parameter is optimized using a local ‘greedy’ scheme along with Shannon wavelet entropy criterion. Then, to further reduce the residual in-band noise in the filtered signal, a spectral subtraction procedure is elaborated after wavelet filtering. Instead of resorting to a reference signal as in the majority of papers in the literature, the new method estimates the power spectral density of the in-band noise from the associated PF. The effectiveness of the proposed method is validated using simulated data, test rig data, and vibration data recorded from the transmission system of a helicopter. The experimental results and comparisons with other methods indicate that the proposed method is an effective approach to detecting the fault-related impulses

  19. Study on the effects of sample selection on spectral reflectance reconstruction based on the algorithm of compressive sensing

    International Nuclear Information System (INIS)

    Zhang, Leihong; Liang, Dong

    2016-01-01

    In order to solve the problem that reconstruction efficiency and precision is not high, in this paper different samples are selected to reconstruct spectral reflectance, and a new kind of spectral reflectance reconstruction method based on the algorithm of compressive sensing is provided. Four different color numbers of matte color cards such as the ColorChecker Color Rendition Chart and Color Checker SG, the copperplate paper spot color card of Panton, and the Munsell colors card are chosen as training samples, the spectral image is reconstructed respectively by the algorithm of compressive sensing and pseudo-inverse and Wiener, and the results are compared. These methods of spectral reconstruction are evaluated by root mean square error and color difference accuracy. The experiments show that the cumulative contribution rate and color difference of the Munsell colors card are better than those of the other three numbers of color cards in the same conditions of reconstruction, and the accuracy of the spectral reconstruction will be affected by the training sample of different numbers of color cards. The key technology of reconstruction means that the uniformity and representation of the training sample selection has important significance upon reconstruction. In this paper, the influence of the sample selection on the spectral image reconstruction is studied. The precision of the spectral reconstruction based on the algorithm of compressive sensing is higher than that of the traditional algorithm of spectral reconstruction. By the MATLAB simulation results, it can be seen that the spectral reconstruction precision and efficiency are affected by the different color numbers of the training sample. (paper)

  20. Facile synthesis of RuII Schiff base complexes: spectral characterization and antimicrobial applications

    International Nuclear Information System (INIS)

    Arunachalam, S.; Padma Priya, N.; Shahul Meeran, H.

    2014-01-01

    Diamagnetic ruthenium (II) complexes of the type (RuCl (CO) (pyridine) (L)) (where L = monobasic tridentate Schiff base ligands) were synthesized by the reactions of Schiff bases derived from the reactions of o-aminobenzoic acid and Knovenegal condensate of β - ketoesters and appropriate ruthenium metal precursor (RuHCl (CO) (PPh 3 ) 2 (py)). Elemental analyses and spectral (FT-IR, UV-Vi s and 1 H, 31 P NMR) studies of all the new synthesized complexes suggest the presence of an octahedral environment around the Ru II ion. Cyclic voltammograms of all the complexes display oxidation and reduction potentials. Superoxide dismutase activity (SOD) of these complexes has also been examined. These complexes were also subjected to study their biocidal activity against Staphylococcus epidermidis, Escherichia coli, Botrytis cinerea and Aspergillus niger. (author)

  1. Fourier transform infrared spectroscopy microscopic imaging classification based on spatial-spectral features

    Science.gov (United States)

    Liu, Lian; Yang, Xiukun; Zhong, Mingliang; Liu, Yao; Jing, Xiaojun; Yang, Qin

    2018-04-01

    The discrete fractional Brownian incremental random (DFBIR) field is used to describe the irregular, random, and highly complex shapes of natural objects such as coastlines and biological tissues, for which traditional Euclidean geometry cannot be used. In this paper, an anisotropic variable window (AVW) directional operator based on the DFBIR field model is proposed for extracting spatial characteristics of Fourier transform infrared spectroscopy (FTIR) microscopic imaging. Probabilistic principal component analysis first extracts spectral features, and then the spatial features of the proposed AVW directional operator are combined with the former to construct a spatial-spectral structure, which increases feature-related information and helps a support vector machine classifier to obtain more efficient distribution-related information. Compared to Haralick’s grey-level co-occurrence matrix, Gabor filters, and local binary patterns (e.g. uniform LBPs, rotation-invariant LBPs, uniform rotation-invariant LBPs), experiments on three FTIR spectroscopy microscopic imaging datasets show that the proposed AVW directional operator is more advantageous in terms of classification accuracy, particularly for low-dimensional spaces of spatial characteristics.

  2. [Research on symmetrical optical waveguide based surface plasmon resonance sensing with spectral interrogation].

    Science.gov (United States)

    Zhang, Yi-long; Liu, Le; Guo, Jun; Zhang, Peng-fei; Guo, Ji-hua; Ma, Hui; He, Yong-hong

    2015-02-01

    Surface plasmon resonance (SPR) sensors with spectral interrogation can adopt fiber to transmit light signals, thus leaving the sensing part separated, which is very convenient for miniaturization, remote-sensing and on-site analysis. Symmetrical optical waveguide (SOW) SPR has the same refractive index of the-two buffer media layers adjacent to the metal film, resulting in longer propagation distance, deeper penetration depth and better performance compared to conventional SPR In the present paper, we developed a symmetrical optical, waveguide (SOW) SPR sensor with wavelength interrogation. In the system, MgF2-Au-MgF2 film was used as SOW module for glucose sensing, and a fiber based light source and detection was used in the spectral interrogation. In the experiment, a refractive index resolution of 2.8 x 10(-7) RIU in fluid protocol was acquired. This technique provides advantages of high resolution and could have potential use in compact design, on-site analysis and remote sensing.

  3. [Vegetation index estimation by chlorophyll content of grassland based on spectral analysis].

    Science.gov (United States)

    Xiao, Han; Chen, Xiu-Wan; Yang, Zhen-Yu; Li, Huai-Yu; Zhu, Han

    2014-11-01

    Comparing the methods of existing remote sensing research on the estimation of chlorophyll content, the present paper confirms that the vegetation index is one of the most practical and popular research methods. In recent years, the increasingly serious problem of grassland degradation. This paper, firstly, analyzes the measured reflectance spectral curve and its first derivative curve in the grasslands of Songpan, Sichuan and Gongger, Inner Mongolia, conducts correlation analysis between these two spectral curves and chlorophyll content, and finds out the regulation between REP (red edge position) and grassland chlorophyll content, that is, the higher the chlorophyll content is, the higher the REIP (red-edge inflection point) value would be. Then, this paper constructs GCI (grassland chlorophyll index) and selects the most suitable band for retrieval. Finally, this paper calculates the GCI by the use of satellite hyperspectral image, conducts the verification and accuracy analysis of the calculation results compared with chlorophyll content data collected from field of twice experiments. The result shows that for grassland chlorophyll content, GCI has stronger sensitivity than other indices of chlorophyll, and has higher estimation accuracy. GCI is the first proposed to estimate the grassland chlorophyll content, and has wide application potential for the remote sensing retrieval of grassland chlorophyll content. In addition, the grassland chlorophyll content estimation method based on remote sensing retrieval in this paper provides new research ideas for other vegetation biochemical parameters' estimation, vegetation growth status' evaluation and grassland ecological environment change's monitoring.

  4. A spatial discretization of the MHD equations based on the finite volume - spectral method

    International Nuclear Information System (INIS)

    Miyoshi, Takahiro

    2000-05-01

    Based on the finite volume - spectral method, we present new discretization formulae for the spatial differential operators in the full system of the compressible MHD equations. In this approach, the cell-centered finite volume method is adopted in a bounded plane (poloidal plane), while the spectral method is applied to the differential with respect to the periodic direction perpendicular to the poloidal plane (toroidal direction). Here, an unstructured grid system composed of the arbitrary triangular elements is utilized for constructing the cell-centered finite volume method. In order to maintain the divergence free constraint of the magnetic field numerically, only the poloidal component of the rotation is defined at three edges of the triangular element. This poloidal component is evaluated under the assumption that the toroidal component of the operated vector times the radius, RA φ , is linearly distributed in the element. The present method will be applied to the nonlinear MHD dynamics in an realistic torus geometry without the numerical singularities. (author)

  5. Detection of nitric acid and nitric oxides in the terrestrial atmosphere in the middle-infrared spectral region

    Directory of Open Access Journals (Sweden)

    M. I. Blecka

    1996-11-01

    Full Text Available A proposal for combined space and ground-based observations of the vertical distributions and the column densities of nitric acid and nitric oxide concentrations in the earth's atmosphere is discussed. We focus on the aspects that are particular to the idea of correlative measurements: geometrical considerations, simulations of the solar absorption spectra in the middle-infrared region corresponding to the different observational geometries, and the associated retrieval methods. These studies are done specifically for the Belgian-French experiment MIRAS (MIR Infrared Atmospheric Spectrometer onboard the Russian Space Station MIR and correlative ground-based FTIR measurements in the Tatra mountains.

  6. Depth of magnetic basement in Iran based on fractal spectral analysis of aeromagnetic data

    Science.gov (United States)

    Teknik, Vahid; Ghods, Abdolreza

    2017-06-01

    To estimate the shape of sedimentary basins, a critical parameter in hydrocarbon exploration, we calculated the depth of magnetic basement by applying a fractal spectral method to the aeromagnetic map of Iran. The depth of magnetic basement is a close proxy for the shape of sedimentary basins provided that igneous basement is strongly magnetized relative to the overlying sediments and there is no interbedding magnetic layer in the sediments. The shape of the power spectrum of magnetic anomalies is sensitive to the depth of magnetic basement, the thickness of the magnetic layer, the fractal parameter of magnetization and the size of the window used for the calculation of the power spectrum. Using a suite of synthetic tests, we have shown that the estimation of the depth of magnetic basement of up to 20 km is not very sensitive to the often unknown fractal parameter and thus the spectral method is a reliable tool to calculate the depth of magnetic basement. The depth of magnetic basement is in the range of 7-16 km in the Zagros, east Alborz, Tabas, Jazmurian and Makran regions, showing a close correlation with depths estimated from the maximum thickness of stratigraphic columns. We have also found new sedimentary basins in Bostan Abad, Bijar and south of Orumiyeh Lake. The significant depth of the magnetic basement in the Makran, Jazmurain depression, southeast Caspian Sea, Tabas, Great Kavir, south of Orumiyeh Lake, Bostan Abad and Bijar sedimentary basins makes them future prospects for hydrocarbon explorations. The depth of magnetic basement is strongly reduced over the Neyriz and Kermanshah Ophiolites, but it does not show any meaningful correlation with other outcrops of ophiolitic rocks in Iran.

  7. Fingerprints of endogenous process on Europa through linear spectral modeling of ground-based observations (ESO/VLT/SINFONI)

    Science.gov (United States)

    Ligier, Nicolas; Carter, John; Poulet, François; Langevin, Yves; Dumas, Christophe; Gourgeot, Florian

    2016-04-01

    Jupiter's moon Europa harbors a very young surface dated, based on cratering rates, to 10-50 M.y (Zahnle et al. 1998, Pappalardo et al. 1999). This young age implies rapid surface recycling and reprocessing, partially engendered by a global salty subsurface liquid ocean that could result in tectonic activity (Schmidt et al. 2011, Kattenhorn et al. 2014) and active plumes (Roth et al. 2014). The surface of Europa should contain important clues about the composition of this sub-surface briny ocean and about the potential presence of material of exobiological interest in it, thus reinforcing Europa as a major target of interest for upcoming space missions such as the ESA L-class mission JUICE. To perform the investigation of the composition of the surface of Europa, a global mapping campaign of the satellite was performed between October 2011 and January 2012 with the integral field spectrograph SINFONI on the Very Large Telescope (VLT) in Chile. The high spectral binning of this instrument (0.5 nm) is suitable to detect any narrow mineral signature in the wavelength range 1.45-2.45 μm. The spatially resolved spectra we obtained over five epochs nearly cover the entire surface of Europa with a pixel scale of 12.5 by 25 m.a.s (~35 by 70 km on Europa's surface), thus permitting a global scale study. Until recently, a large majority of studies only proposed sulfate salts along with sulfuric acid hydrate and water-ice to be present on Europa's surface. However, recent works based on Europa's surface coloration in the visible wavelength range and NIR spectral analysis support the hypothesis of the predominance of chlorine salts instead of sulfate salts (Hand & Carlson 2015, Fischer et al. 2015). Our linear spectral modeling supports this new hypothesis insofar as the use of Mg-bearing chlorines improved the fits whatever the region. As expected, the distribution of sulfuric acid hydrate is correlated to the Iogenic sulfur ion implantation flux distribution (Hendrix et al

  8. Spectral negentropy based sidebands and demodulation analysis for planet bearing fault diagnosis

    Science.gov (United States)

    Feng, Zhipeng; Ma, Haoqun; Zuo, Ming J.

    2017-12-01

    Planet bearing vibration signals are highly complex due to intricate kinematics (involving both revolution and spinning) and strong multiple modulations (including not only the fault induced amplitude modulation and frequency modulation, but also additional amplitude modulations due to load zone passing, time-varying vibration transfer path, and time-varying angle between the gear pair mesh lines of action and fault impact force vector), leading to difficulty in fault feature extraction. Rolling element bearing fault diagnosis essentially relies on detection of fault induced repetitive impulses carried by resonance vibration, but they are usually contaminated by noise and therefor are hard to be detected. This further adds complexity to planet bearing diagnostics. Spectral negentropy is able to reveal the frequency distribution of repetitive transients, thus providing an approach to identify the optimal frequency band of a filter for separating repetitive impulses. In this paper, we find the informative frequency band (including the center frequency and bandwidth) of bearing fault induced repetitive impulses using the spectral negentropy based infogram. In Fourier spectrum, we identify planet bearing faults according to sideband characteristics around the center frequency. For demodulation analysis, we filter out the sensitive component based on the informative frequency band revealed by the infogram. In amplitude demodulated spectrum (squared envelope spectrum) of the sensitive component, we diagnose planet bearing faults by matching the present peaks with the theoretical fault characteristic frequencies. We further decompose the sensitive component into mono-component intrinsic mode functions (IMFs) to estimate their instantaneous frequencies, and select a sensitive IMF with an instantaneous frequency fluctuating around the center frequency for frequency demodulation analysis. In the frequency demodulated spectrum (Fourier spectrum of instantaneous frequency) of

  9. Spectrally selective solar absorber with sharp and temperature dependent cut-off based on semiconductor nanowire arrays

    Science.gov (United States)

    Wang, Yang; Zhou, Lin; Zheng, Qinghui; Lu, Hong; Gan, Qiaoqiang; Yu, Zongfu; Zhu, Jia

    2017-05-01

    Spectrally selective absorbers (SSA) with high selectivity of absorption and sharp cut-off between high absorptivity and low emissivity are critical for efficient solar energy conversion. Here, we report the semiconductor nanowire enabled SSA with not only high absorption selectivity but also temperature dependent sharp absorption cut-off. By taking advantage of the temperature dependent bandgap of semiconductors, we systematically demonstrate that the absorption cut-off profile of the semiconductor-nanowire-based SSA can be flexibly tuned, which is quite different from most of the other SSA reported so far. As an example, silicon nanowire based selective absorbers are fabricated, with the measured absorption efficiency above (below) bandgap ˜97% (15%) combined with an extremely sharp absorption cut-off (transition region ˜200 nm), the sharpest SSA demonstrated so far. The demonstrated semiconductor-nanowire-based SSA can enable a high solar thermal efficiency of ≳86% under a wide range of operating conditions, which would be competitive candidates for the concentrated solar energy utilizations.

  10. Constructing regional advantage: platform policies based on related variety and differentiated knowledge bases.

    NARCIS (Netherlands)

    Asheim, B.T.; Boschma, R.A.; Cooke, P.

    2011-01-01

    Constructing regional advantage: platform policies based on related variety and differentiated knowledge bases, Regional Studies. This paper presents a regional innovation policy model based on the idea of constructing regional advantage. This policy model brings together concepts like related

  11. Complex refractive indices in the near-ultraviolet spectral region of biogenic secondary organic aerosol aged with ammonia

    Energy Technology Data Exchange (ETDEWEB)

    Flores, J. M.; Washenfelder, Rebecca; Adler, Gabriela; Lee, H-J; Segev, Lior; Laskin, Julia; Laskin, Alexander; Nizkorodov, Sergey; Brown, Steven; Rudich, Yinon

    2014-05-14

    Atmospheric absorption by brown carbon aerosol may play an important role in global radiative forcing. Brown carbon arises from both primary and secondary sources, but the mechanisms and reactions for the latter are highly uncertain. One proposed mechanism is the reaction of ammonia or amino acids with carbonyl products in secondary organic aerosol (SOA). We generated SOA in situ by reacting biogenic alkenes (α-pinene, limonene, and α-humulene) with excess ozone, humidifying the resulting aerosol, and reacting the humidified aerosol with gaseous ammonia. We determined the complex refractive indices (RI) in the 360 – 420 nm range for these aerosols using broadband cavity enhanced spectroscopy (BBCES). The average real part (n) of the measured spectral range of the NH3-aged α-pinene SOA increased from n = 1.50 (±0.01) for the unreacted SOA to n = 1.57 (± 0.01) after a 1.5h exposure to 1.9 ppm NH3; whereas,the imaginary component (k) remained below k < 0.001 (± 0.002). For the limonene and α-humulene SOA the real part did not change significantly, and we observed a small change in the imaginary component of the RI. The imaginary component increased from k = 0.0 to an average k= 0.029 (± 0.021) for α-humulene SOA, and from k < 0.001 (± 0.002) to an average k = 0.032 (±0.019) for limonene SOA after a 1.5 h exposure to 1.3 and 1.9 ppm of NH3, respectively. Collected filter samples of the aged and unreacted α-pinene SOA and limonene SOA were analyzed off-line with nanospray desorption electrospray ionization high resolution mass spectrometry (nano-DESI/HR-MS), and in-situ with a Time-of-Fligh Aerosol Mass Spectrometer, confirming that the SOA reacted and that various nitrogen-containing reaction products formed. If we assume that NH3 aging reactions scale linearly with time and concentration, then a 1.5 h reaction with 1 ppm NH3 in the laboratory is equivalent to 24 h reaction with 63 ppbv NH3, indicating that the observed aerosol absorption will be limited

  12. Semifragile Speech Watermarking Based on Least Significant Bit Replacement of Line Spectral Frequencies

    Directory of Open Access Journals (Sweden)

    Mohammad Ali Nematollahi

    2017-01-01

    Full Text Available There are various techniques for speech watermarking based on modifying the linear prediction coefficients (LPCs; however, the estimated and modified LPCs vary from each other even without attacks. Because line spectral frequency (LSF has less sensitivity to watermarking than LPC, watermark bits are embedded into the maximum number of LSFs by applying the least significant bit replacement (LSBR method. To reduce the differences between estimated and modified LPCs, a checking loop is added to minimize the watermark extraction error. Experimental results show that the proposed semifragile speech watermarking method can provide high imperceptibility and that any manipulation of the watermark signal destroys the watermark bits since manipulation changes it to a random stream of bits.

  13. Synthesis, spectral characterizations and antimicrobial activity of some Schiff bases of 4-chloro-2-aminophenol

    Directory of Open Access Journals (Sweden)

    A. Seher Birteksöz

    2011-12-01

    Full Text Available A series of 4-chloro-2-[(arylmethylideneamino]phenols (1–11 including methoxy group were synthesized using appropriate synthetic route. The structures of the Schiff bases were characterized by FT-IR, UV-Vis, ESI-MS, 1H and 13C-NMR spectroscopic techniques and analytical methods. A relation is observed between melting points and existence of intramolecular hydrogen bonding. IR spectra of the compounds including and not including hydrogen bonding were compared. The compounds 2 and 4 show the characteristic UV bands attributed to the NH-forms. According to the 1H-NMR spectral data the compound 2 has the strongest intramolecular hydrogen bonding and the compound 6 shows two isomeric structure. On the other hand, antibacterial and antifungal activities of the compounds were investigated. Most of the compounds show selective activity toward S. epidermidis and C. albicans.

  14. Quantitative measurement of phase variation amplitude of ultrasonic diffraction grating based on diffraction spectral analysis

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Meiyan, E-mail: yphantomohive@gmail.com; Zeng, Yingzhi; Huang, Zuohua, E-mail: zuohuah@163.com [Laboratory of Quantum Engineering and Quantum Materials, School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou, Guangdong 510006 (China)

    2014-09-15

    A new method based on diffraction spectral analysis is proposed for the quantitative measurement of the phase variation amplitude of an ultrasonic diffraction grating. For a traveling wave, the phase variation amplitude of the grating depends on the intensity of the zeroth- and first-order diffraction waves. By contrast, for a standing wave, this amplitude depends on the intensity of the zeroth-, first-, and second-order diffraction waves. The proposed method is verified experimentally. The measured phase variation amplitude ranges from 0 to 2π, with a relative error of approximately 5%. A nearly linear relation exists between the phase variation amplitude and driving voltage. Our proposed method can also be applied to ordinary sinusoidal phase grating.

  15. High Spectral Resolution Lidar Based on a Potassium Faraday Dispersive Filter for Daytime Temperature Measurement

    Directory of Open Access Journals (Sweden)

    Abo Makoto

    2016-01-01

    Full Text Available In this paper, a new high-spectral-resolution lidar technique is proposed for measuring the profiles of atmospheric temperature in daytime. Based on the theory of high resolution Rayleigh scattering, the feasibility and advantages of using potassium (K Faraday dispersive optical filters as blocking filters for measuring atmospheric temperature are demonstrated with a numerical simulation. It was found that temperature profiles could be measured within 1K error for the height of 9 km with a 500 m range resolution in 60 min by using laser pulses with 1mJ/pulse and 1 kHz, and a 50 cm diameter telescope. Furthermore, we are developing compact pulsed laser system for temperature lidar transmitter.

  16. Removal of Thin Cirrus Path Radiances in the 0.4-1.0 micron Spectral Region Using the 1.375-micron Strong Water Vapor Absorption Channel

    Science.gov (United States)

    Gao, Bo-Cai; Kaufman, Yoram J.; Han, Wei; Wiscombe, Warren J.

    1998-01-01

    Through analysis of spectral imaging data acquired with the Airborne Visible Infrared Imaging Spectrometer (AVIRIS) from an ER-2 aircraft at 20 km altitude during several field programs, it was found that narrow channels near the center of the strong 1.38-micron water vapor band are very sensitive in detecting thin cirrus clouds. Based on this observation from AVIRIS data, a channel centered at 1.375 microns with a width of 30 nm was selected for the Moderate Resolution Imaging Spectrometer (MODIS) for remote sensing of cirrus clouds from space. The sensitivity of the 1.375-micron MODIS channel to detect thin cirrus clouds during the day time is expected to be one to two orders of magnitude better than the current infrared emission techniques. As a result, a larger fraction of the satellite data will likely be identified as containing cirrus clouds. In order to make better studies of surface reflectance properties, thin cirrus effects must be removed from satellite images. We have developed an empirical approach for removing/correcting thin cirrus effects in the 0.4 - 1.0 micron region using channels near 1.375 microns. This algorithm will be incorporated into the present MODIS atmospheric correction algorithms for ocean color and land applications and will yield improved MODIS atmospheric aerosol, land surface, and ocean color products.

  17. Spectral domain, common path OCT in a handheld PIC based system

    Science.gov (United States)

    Leinse, Arne; Wevers, Lennart; Marchenko, Denys; Dekker, Ronald; Heideman, René G.; Ruis, Roosje M.; Faber, Dirk J.; van Leeuwen, Ton G.; Kim, Keun Bae; Kim, Kyungmin

    2018-02-01

    Optical Coherence Tomography (OCT) has made it into the clinic in the last decade with systems based on bulk optical components. The next disruptive step will be the introduction of handheld OCT systems. Photonic Integrated Circuit (PIC) technology is the key enabler for this further miniaturization. PIC technology allows signal processing on a stable platform and the implementation of a common path interferometer in that same platform creates a robust fully integrated OCT system with a flexible fiber probe. In this work the first PIC based handheld and integrated common path based spectral domain OCT system is described and demonstrated. The spectrometer in the system is based on an Arrayed Waveguide Grating (AWG) and fully integrated with the CCD and a fiber probe into a system operating at 850 nm. The AWG on the PIC creates a 512 channel spectrometer with a resolution of 0.22 nm enabling a high speed analysis of the full A-scan. The silicon nitride based proprietary waveguide technology (TriPleXTM) enables low loss complex photonic structures from the visible (405 nm) to IR (2350 nm) range, making it a unique candidate for OCT applications. Broadband AWG operation from visible to 1700 nm has been shown in the platform and Photonic Design Kits (PDK) are available enabling custom made designs in a system level design environment. This allows a low threshold entry for designing new (OCT) designs for a broad wavelength range.

  18. A method for spectral DNS of low Rm channel flows based on the least dissipative modes

    Science.gov (United States)

    Kornet, Kacper; Pothérat, Alban

    2015-10-01

    We put forward a new type of spectral method for the direct numerical simulation of flows where anisotropy or very fine boundary layers are present. The main idea is to take advantage of the fact that such structures are dissipative and that their presence should reduce the number of degrees of freedom of the flow, when paradoxically, their fine resolution incurs extra computational cost in most current methods. The principle of this method is to use a functional basis with elements that already include these fine structures so as to avoid these extra costs. This leads us to develop an algorithm to implement a spectral method for arbitrary functional bases, and in particular, non-orthogonal ones. We construct a basic implementation of this algorithm to simulate magnetohydrodynamic (MHD) channel flows with an externally imposed, transverse magnetic field, where very thin boundary layers are known to develop along the channel walls. In this case, the sought functional basis can be built out of the eigenfunctions of the dissipation operator, which incorporate these boundary layers, and it turns out to be non-orthogonal. We validate this new scheme against numerical simulations of freely decaying MHD turbulence based on a finite volume code and it is found to provide accurate results. Its ability to fully resolve wall-bounded turbulence with a number of modes close to that required by the dynamics is demonstrated on a simple example. This opens the way to full-blown simulations of MHD turbulence under very high magnetic fields. Until now such simulations were too computationally expensive. In contrast to traditional methods the computational cost of the proposed method, does not depend on the intensity of the magnetic field.

  19. The spectral theorem for quaternionic unbounded normal operators based on the S-spectrum

    Energy Technology Data Exchange (ETDEWEB)

    Alpay, Daniel, E-mail: dany@math.bgu.ac.il; Kimsey, David P., E-mail: dpkimsey@gmail.com [Department of Mathematics, Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel); Colombo, Fabrizio, E-mail: fabrizio.colombo@polimi.it [Politecnico di Milano, Dipartimento di Matematica, Via E. Bonardi, 9, 20133 Milano (Italy)

    2016-02-15

    In this paper we prove the spectral theorem for quaternionic unbounded normal operators using the notion of S-spectrum. The proof technique consists of first establishing a spectral theorem for quaternionic bounded normal operators and then using a transformation which maps a quaternionic unbounded normal operator to a quaternionic bounded normal operator. With this paper we complete the foundation of spectral analysis of quaternionic operators. The S-spectrum has been introduced to define the quaternionic functional calculus but it turns out to be the correct object also for the spectral theorem for quaternionic normal operators. The lack of a suitable notion of spectrum was a major obstruction to fully understand the spectral theorem for quaternionic normal operators. A prime motivation for studying the spectral theorem for quaternionic unbounded normal operators is given by the subclass of unbounded anti-self adjoint quaternionic operators which play a crucial role in the quaternionic quantum mechanics.

  20. Airborne differential absorption lidar for water vapour measurements in the upper troposphere and lower stratosphere in the spectral region around 940 nm

    Energy Technology Data Exchange (ETDEWEB)

    Poberaj, G.

    2000-07-01

    Two all-solid-state laser systems were developed and studied in detail to optimise their performance for an airborne water vapour differential absorption lidar (DIAL). Their special features are high average output powers and excellent spectral properties in the 940-nm spectral region relevant for monitoring very low water vapour contents in the upper troposphere and lower stratosphere. One system is an injection-seeded pulsed Ti:sapphire ring laser with a spectral bandwidth of 105 MHz and an average power of 1.1 W. The other system is an injection-seeded optical parametric oscillator (OPO) in a ring configuration. Using KTP as nonlinear crystal, a signal output with a spectral bandwidth of 140 MHz and an average power of 1.2 W was achieved. Both systems, the Ti:sapphire ring laser and the KTP OPO, possess spectral purity values higher than 99%. The pump source for these systems is a frequency doubled diode-pumped Nd:YAG laser operating at a repetition rate of 100 Hz. The KTP OPO system has been used as a transmitter in a new airborne water vapour DIAL instrument. For the first time, measurements of two-dimensional water vapour distributions with a high vertical (500 m) and horizontal (20 km) resolution across several potential vorticity streamers were performed. Very low water vapour mixing ratios (10-50 ppmv) and strong gradients were observed in the tropopause region. The sensitivity of the DIAL instrument in the centre of a stratospheric intrusion ranges from 3% in the near field to 12% in the far field (4 km). The first comparison experiments with in situ measuring instruments show a good agreement. Considerable differences are found between DIAL measurements and data obtained from the ECMWF operational analyses and a mesoscale numerical model. (orig.)

  1. Multi region based image retrieval system

    Indian Academy of Sciences (India)

    data mining, information theory, statistics and psychology. ∗ .... ground complication and independent of image size and orientation (Zhang 2007). ..... Figure 2. Significant regions: (a) the input image, (b) the primary significant region, (c) the ...

  2. Spectral embedding based active contour (SEAC) for lesion segmentation on breast dynamic contrast enhanced magnetic resonance imaging.

    Science.gov (United States)

    Agner, Shannon C; Xu, Jun; Madabhushi, Anant

    2013-03-01

    Segmentation of breast lesions on dynamic contrast enhanced (DCE) magnetic resonance imaging (MRI) is the first step in lesion diagnosis in a computer-aided diagnosis framework. Because manual segmentation of such lesions is both time consuming and highly susceptible to human error and issues of reproducibility, an automated lesion segmentation method is highly desirable. Traditional automated image segmentation methods such as boundary-based active contour (AC) models require a strong gradient at the lesion boundary. Even when region-based terms are introduced to an AC model, grayscale image intensities often do not allow for clear definition of foreground and background region statistics. Thus, there is a need to find alternative image representations that might provide (1) strong gradients at the margin of the object of interest (OOI); and (2) larger separation between intensity distributions and region statistics for the foreground and background, which are necessary to halt evolution of the AC model upon reaching the border of the OOI. In this paper, the authors introduce a spectral embedding (SE) based AC (SEAC) for lesion segmentation on breast DCE-MRI. SE, a nonlinear dimensionality reduction scheme, is applied to the DCE time series in a voxelwise fashion to reduce several time point images to a single parametric image where every voxel is characterized by the three dominant eigenvectors. This parametric eigenvector image (PrEIm) representation allows for better capture of image region statistics and stronger gradients for use with a hybrid AC model, which is driven by both boundary and region information. They compare SEAC to ACs that employ fuzzy c-means (FCM) and principal component analysis (PCA) as alternative image representations. Segmentation performance was evaluated by boundary and region metrics as well as comparing lesion classification using morphological features from SEAC, PCA+AC, and FCM+AC. On a cohort of 50 breast DCE-MRI studies, Pr

  3. On exploiting wavelet bases in statistical region-based segmentation

    DEFF Research Database (Denmark)

    Stegmann, Mikkel Bille; Forchhammer, Søren

    2002-01-01

    Statistical region-based segmentation methods such as the Active Appearance Models establish dense correspondences by modelling variation of shape and pixel intensities in low-resolution 2D images. Unfortunately, for high-resolution 2D and 3D images, this approach is rendered infeasible due to ex...... 9-7 wavelet on cardiac MRIs and human faces show that the segmentation accuracy is minimally degraded at compression ratios of 1:10 and 1:20, respectively....

  4. Preparation of dental amalgam and spectral diagnosis of mercury in plasmas-laser in the region of 250 nm – 850 nm

    International Nuclear Information System (INIS)

    Ossa, A De la; Pacheco, P; Sarmiento, R

    2013-01-01

    In this paper we presents results of the spectral study of plasmas-laser of dental amalgam by technique Laser-induced Breakdown Spectroscopy (LIBS). Plasmas were generated focusing the beam of a Nd: YAG laser on the matrix of the mixture Ag-Sn-Cu and on amalgams with different proportions of mercury (3:2, 5:2, 6:2). Based on the spectral results and reported atomic parameters, became estimation of electron temperature plasmas- laser and their behavior with the concentration of Hg. The estimated values of the electron temperature for the respective proportions were 20 846 K, 19 139 K and 16 872 K, using the distribution of population of Boltzmann energy levels associated with spectral lines, considering conditions Local Thermodinamic Equilibrium (LTE) of plasmas

  5. Spectral analysis and classification of igneous and metamorphic rocks of Hamedan region for remote sensing studies; using laboratory reflectance spectra (350-2500 nm)

    International Nuclear Information System (INIS)

    Rangzan, K.; Saki, A.; Hassanshahi, H.; Mojaradi, B.

    2012-01-01

    Reflectance spectrometry techniques with the integration of remote sensing data help us in identifying and mapping the phenomena on the earth. Using these techniques to discriminate the petrologic units independently and without knowing the spectral behavior of rocks along the electromagnetic wavelengths can not be so much useful. For the purposes of this study, 65 samples of igneous and metamorphic rocks from Hamedan region were collected and their spectra were measured using Fieldspec3 device in laboratory. The spectra were analyzed on the basis of absorption, position and shape. Petrographic analyses were used to interpret the absorption patterns as well. Then the spectra were classified according to spectral patterns. This measurement was done on both freshly cut and exposed surfaces of the samples and except a few samples, the two sets of spectra did not differ significantly. Finally, to evaluate the possibility of recognition of these targets, the responses of two hyper spectral and multispectral sensors were simulated from spectra representative of the spectral classes, showing that significant identification and classification of well exposed rocks are potentially possible using remote instruments providing high quality spectra. Also Aster simulation showed that a preliminary gross discrimination of rocks was however possible.

  6. A New Spectral Shape-Based Record Selection Approach Using Np and Genetic Algorithms

    Directory of Open Access Journals (Sweden)

    Edén Bojórquez

    2013-01-01

    Full Text Available With the aim to improve code-based real records selection criteria, an approach inspired in a parameter proxy of spectral shape, named Np, is analyzed. The procedure is based on several objectives aimed to minimize the record-to-record variability of the ground motions selected for seismic structural assessment. In order to select the best ground motion set of records to be used as an input for nonlinear dynamic analysis, an optimization approach is applied using genetic algorithms focuse on finding the set of records more compatible with a target spectrum and target Np values. The results of the new Np-based approach suggest that the real accelerograms obtained with this procedure, reduce the scatter of the response spectra as compared with the traditional approach; furthermore, the mean spectrum of the set of records is very similar to the target seismic design spectrum in the range of interest periods, and at the same time, similar Np values are obtained for the selected records and the target spectrum.

  7. Design and Analysis of Self-Healing Tree-Based Hybrid Spectral Amplitude Coding OCDMA System

    Directory of Open Access Journals (Sweden)

    Waqas A. Imtiaz

    2017-01-01

    Full Text Available This paper presents an efficient tree-based hybrid spectral amplitude coding optical code division multiple access (SAC-OCDMA system that is able to provide high capacity transmission along with fault detection and restoration throughout the passive optical network (PON. Enhanced multidiagonal (EMD code is adapted to elevate system’s performance, which negates multiple access interference and associated phase induced intensity noise through efficient two-matrix structure. Moreover, system connection availability is enhanced through an efficient protection architecture with tree and star-ring topology at the feeder and distribution level, respectively. The proposed hybrid architecture aims to provide seamless transmission of information at minimum cost. Mathematical model based on Gaussian approximation is developed to analyze performance of the proposed setup, followed by simulation analysis for validation. It is observed that the proposed system supports 64 subscribers, operating at the data rates of 2.5 Gbps and above. Moreover, survivability and cost analysis in comparison with existing schemes show that the proposed tree-based hybrid SAC-OCDMA system provides the required redundancy at minimum cost of infrastructure and operation.

  8. Ontology-based classification of remote sensing images using spectral rules

    Science.gov (United States)

    Andrés, Samuel; Arvor, Damien; Mougenot, Isabelle; Libourel, Thérèse; Durieux, Laurent

    2017-05-01

    Earth Observation data is of great interest for a wide spectrum of scientific domain applications. An enhanced access to remote sensing images for "domain" experts thus represents a great advance since it allows users to interpret remote sensing images based on their domain expert knowledge. However, such an advantage can also turn into a major limitation if this knowledge is not formalized, and thus is difficult for it to be shared with and understood by other users. In this context, knowledge representation techniques such as ontologies should play a major role in the future of remote sensing applications. We implemented an ontology-based prototype to automatically classify Landsat images based on explicit spectral rules. The ontology is designed in a very modular way in order to achieve a generic and versatile representation of concepts we think of utmost importance in remote sensing. The prototype was tested on four subsets of Landsat images and the results confirmed the potential of ontologies to formalize expert knowledge and classify remote sensing images.

  9. Landsat sattelite multi-spectral image classification of land cover and land use changes for GIS-based urbanization analysis in irrigation districts of lower Rio Grande Valley of Texas

    Science.gov (United States)

    The Lower Rio Grande Valley in the south of Texas is experiencing rapid increase of population to bring up urban growth that continues influencing on the irrigation districts in the region. This study evaluated the Landsat satellite multi-spectral imagery to provide information for GIS-based urbaniz...

  10. Temperature Dependences of the Quantum-Mechanical and Semi-Classical Spectral-Line Widths and the Separation 0 of the Impact and Non-Impact Regions for an Ar-Perturbed/K-Radiator System

    Directory of Open Access Journals (Sweden)

    W. C. Kreye

    2010-01-01

    Full Text Available Quantum-mechanical and semi-classical spectral-line shapes are computed at =400, 800, and 1000 K for the line core of the 5802 Å line of the Ar-Perturbed/K-Radiator system. HWHMs ('s are measured from computed full spectral-line shapes. The final-state pseudopotential is for the 721/2 state, and the initial-state potential is for the 423/2,3/2 state. Three high-pressure (P log(—versus—log( curves, corresponding to the non-impact region, intersect a similar set of low-P, impact-region curves at intersections, 0's. Similarly, for two sets of log(—versus—log( curves, which yield intersections, 0's, where is the perturber density. These 0's and 0's separate the two regions and represent the upper limits of the impact regions. A specific validity condition for the impact region is given by the equation ≤0. From an earlier spectroscopic, Fabry-Perot paper, expt=0.021 cm−1 at =400 K and =10 torr. Two theoretical values, theor=0.025 and 0.062 cm−1 corresponding to two different pseudo-potentials, are reported. Two -dependent figures are given, in which the first shows an increase in the impact region with , based on as the basic parameter, and the second which shows a decrease in the impact region with , based on as the basic parameter.

  11. Fluvial reservoir characterization using topological descriptors based on spectral analysis of graphs

    Science.gov (United States)

    Viseur, Sophie; Chiaberge, Christophe; Rhomer, Jérémy; Audigane, Pascal

    2015-04-01

    Fluvial systems generate highly heterogeneous reservoir. These heterogeneities have major impact on fluid flow behaviors. However, the modelling of such reservoirs is mainly performed in under-constrained contexts as they include complex features, though only sparse and indirect data are available. Stochastic modeling is the common strategy to solve such problems. Multiple 3D models are generated from the available subsurface dataset. The generated models represent a sampling of plausible subsurface structure representations. From this model sampling, statistical analysis on targeted parameters (e.g.: reserve estimations, flow behaviors, etc.) and a posteriori uncertainties are performed to assess risks. However, on one hand, uncertainties may be huge, which requires many models to be generated for scanning the space of possibilities. On the other hand, some computations performed on the generated models are time consuming and cannot, in practice, be applied on all of them. This issue is particularly critical in: 1) geological modeling from outcrop data only, as these data types are generally sparse and mainly distributed in 2D at large scale but they may locally include high-resolution descriptions (e.g.: facies, strata local variability, etc.); 2) CO2 storage studies as many scales of investigations are required, from meter to regional ones, to estimate storage capacities and associated risks. Recent approaches propose to define distances between models to allow sophisticated multivariate statistics to be applied on the space of uncertainties so that only sub-samples, representative of initial set, are investigated for dynamic time-consuming studies. This work focuses on defining distances between models that characterize the topology of the reservoir rock network, i.e. its compactness or connectivity degree. The proposed strategy relies on the study of the reservoir rock skeleton. The skeleton of an object corresponds to its median feature. A skeleton is

  12. Regional geology mapping using satellite-based remote sensing approach in Northern Victoria Land, Antarctica

    Science.gov (United States)

    Pour, Amin Beiranvand; Park, Yongcheol; Park, Tae-Yoon S.; Hong, Jong Kuk; Hashim, Mazlan; Woo, Jusun; Ayoobi, Iman

    2018-06-01

    Satellite remote sensing imagery is especially useful for geological investigations in Antarctica because of its remoteness and extreme environmental conditions that constrain direct geological survey. The highest percentage of exposed rocks and soils in Antarctica occurs in Northern Victoria Land (NVL). Exposed Rocks in NVL were part of the paleo-Pacific margin of East Gondwana during the Paleozoic time. This investigation provides a satellite-based remote sensing approach for regional geological mapping in the NVL, Antarctica. Landsat-8 and the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) datasets were used to extract lithological-structural and mineralogical information. Several spectral-band ratio indices were developed using Landsat-8 and ASTER bands and proposed for Antarctic environments to map spectral signatures of snow/ice, iron oxide/hydroxide minerals, Al-OH-bearing and Fe, Mg-OH and CO3 mineral zones, and quartz-rich felsic and mafic-to-ultramafic lithological units. The spectral-band ratio indices were tested and implemented to Level 1 terrain-corrected (L1T) products of Landsat-8 and ASTER datasets covering the NVL. The surface distribution of the mineral assemblages was mapped using the spectral-band ratio indices and verified by geological expeditions and laboratory analysis. Resultant image maps derived from spectral-band ratio indices that developed in this study are fairly accurate and correspond well with existing geological maps of the NVL. The spectral-band ratio indices developed in this study are especially useful for geological investigations in inaccessible locations and poorly exposed lithological units in Antarctica environments.

  13. Evaluating visibility of age spot and freckle based on simulated spectral reflectance distribution and facial color image

    Science.gov (United States)

    Hirose, Misa; Toyota, Saori; Tsumura, Norimichi

    2018-02-01

    In this research, we evaluate the visibility of age spot and freckle with changing the blood volume based on simulated spectral reflectance distribution and the actual facial color images, and compare these results. First, we generate three types of spatial distribution of age spot and freckle in patch-like images based on the simulated spectral reflectance. The spectral reflectance is simulated using Monte Carlo simulation of light transport in multi-layered tissue. Next, we reconstruct the facial color image with changing the blood volume. We acquire the concentration distribution of melanin, hemoglobin and shading components by applying the independent component analysis on a facial color image. We reproduce images using the obtained melanin and shading concentration and the changed hemoglobin concentration. Finally, we evaluate the visibility of pigmentations using simulated spectral reflectance distribution and facial color images. In the result of simulated spectral reflectance distribution, we found that the visibility became lower as the blood volume increases. However, we can see that a specific blood volume reduces the visibility of the actual pigmentations from the result of the facial color images.

  14. Studying the extinction coefficient due to aerosol particles at different spectral bands in some regions at great Cairo

    International Nuclear Information System (INIS)

    Shaltout, M.A. Mosalam; Tadros, M.T.Y.; El-Metwally, M.

    2000-01-01

    Extinction coefficient due to aerosol has been estimated by Pyrheliometric and Gorgie type Actinometric measurements in the industrial, urban areas and compared with agricultural areas. The measurements distributed over one year from June 1992 to May 1993 were made under clear sky for five spectral bands. The results show two maxima in hot wet and spring months and minimum in winter months, but there is a fluctuation in urban area. Diurnal variations show maximum at noon especially in the industrial area. Level of extinction coefficient in the industrial and urban area is greater that that of the agricultural area, except for hot wet months is due to the increase of water vapor content in agricultural area. Spectral distribution of the extinction coefficient decreases monotonically with wavelength. Size of particles in industrial area is greater than in urban and agricultural areas. The temperature and water vapor content have important rules in increasing the extinction coefficient of aerosols. (Author)

  15. Spectrally based bathymetric mapping of a dynamic, sand‐bedded channel: Niobrara River, Nebraska, USA

    Science.gov (United States)

    Dilbone, Elizabeth; Legleiter, Carl; Alexander, Jason S.; McElroy, Brandon

    2018-01-01

    Methods for spectrally based mapping of river bathymetry have been developed and tested in clear‐flowing, gravel‐bed channels, with limited application to turbid, sand‐bed rivers. This study used hyperspectral images and field surveys from the dynamic, sandy Niobrara River to evaluate three depth retrieval methods. The first regression‐based approach, optimal band ratio analysis (OBRA), paired in situ depth measurements with image pixel values to estimate depth. The second approach used ground‐based field spectra to calibrate an OBRA relationship. The third technique, image‐to‐depth quantile transformation (IDQT), estimated depth by linking the cumulative distribution function (CDF) of depth to the CDF of an image‐derived variable. OBRA yielded the lowest depth retrieval mean error (0.005 m) and highest observed versus predicted R2 (0.817). Although misalignment between field and image data did not compromise the performance of OBRA in this study, poor georeferencing could limit regression‐based approaches such as OBRA in dynamic, sand‐bedded rivers. Field spectroscopy‐based depth maps exhibited a mean error with a slight shallow bias (0.068 m) but provided reliable estimates for most of the study reach. IDQT had a strong deep bias but provided informative relative depth maps. Overprediction of depth by IDQT highlights the need for an unbiased sampling strategy to define the depth CDF. Although each of the techniques we tested demonstrated potential to provide accurate depth estimates in sand‐bed rivers, each method also was subject to certain constraints and limitations.

  16. Raman spectral signatures of cervical exfoliated cells from liquid-based cytology samples

    Science.gov (United States)

    Kearney, Padraig; Traynor, Damien; Bonnier, Franck; Lyng, Fiona M.; O'Leary, John J.; Martin, Cara M.

    2017-10-01

    It is widely accepted that cervical screening has significantly reduced the incidence of cervical cancer worldwide. The primary screening test for cervical cancer is the Papanicolaou (Pap) test, which has extremely variable specificity and sensitivity. There is an unmet clinical need for methods to aid clinicians in the early detection of cervical precancer. Raman spectroscopy is a label-free objective method that can provide a biochemical fingerprint of a given sample. Compared with studies on infrared spectroscopy, relatively few Raman spectroscopy studies have been carried out to date on cervical cytology. The aim of this study was to define the Raman spectral signatures of cervical exfoliated cells present in liquid-based cytology Pap test specimens and to compare the signature of high-grade dysplastic cells to each of the normal cell types. Raman spectra were recorded from single exfoliated cells and subjected to multivariate statistical analysis. The study demonstrated that Raman spectroscopy can identify biochemical signatures associated with the most common cell types seen in liquid-based cytology samples; superficial, intermediate, and parabasal cells. In addition, biochemical changes associated with high-grade dysplasia could be identified suggesting that Raman spectroscopy could be used to aid current cervical screening tests.

  17. Synthesis and Spectral Characterization of Antifungal Sensitive Schiff Base Transition Metal Complexes

    Science.gov (United States)

    Sakthivel, A.; Rajasekaran, K.

    2007-01-01

    New N2O2 donor type Schiff base has been designed and synthesized by condensing acetoacetanilido-4-aminoantipyrine with 2-aminobenzoic acid in ethanol. Solid metal complexes of the Schiff base with Cu(II), Ni(II), Co(II), Mn(II), Zn(II), VO(IV), Hg(II) and Cd(II) metal ions were synthesized and characterized by elemental analyses, magnetic susceptibility, molar conduction, fast atom bombardment (FAB) mass, IR, UV-Vis, and 1H NMR spectral studies. The data show that the complexes have the composition of ML type. The UV-Vis. and magnetic susceptibility data of the complexes suggest a square-planar geometry around the central metal ion except VO(IV) complex which has square-pyramidal geometry. The in vitro antifungal activities of the compounds were tested against fungi such as Aspergillus niger, Aspergillus flavus, Rhizopus stolonifer, Candida albicans, Rhizoctonia bataicola and Trichoderma harizanum. All the metal complexes showed stronger antifungal activities than the free ligand. The minimum inhibitory concentrations (MIC) of the metal complexes were found in the range of 10~31 µg/ml. PMID:24015086

  18. Image Segmentation Based on Constrained Spectral Variance Difference and Edge Penalty

    Directory of Open Access Journals (Sweden)

    Bo Chen

    2015-05-01

    Full Text Available Segmentation, which is usually the first step in object-based image analysis (OBIA, greatly influences the quality of final OBIA results. In many existing multi-scale segmentation algorithms, a common problem is that under-segmentation and over-segmentation always coexist at any scale. To address this issue, we propose a new method that integrates the newly developed constrained spectral variance difference (CSVD and the edge penalty (EP. First, initial segments are produced by a fast scan. Second, the generated segments are merged via a global mutual best-fitting strategy using the CSVD and EP as merging criteria. Finally, very small objects are merged with their nearest neighbors to eliminate the remaining noise. A series of experiments based on three sets of remote sensing images, each with different spatial resolutions, were conducted to evaluate the effectiveness of the proposed method. Both visual and quantitative assessments were performed, and the results show that large objects were better preserved as integral entities while small objects were also still effectively delineated. The results were also found to be superior to those from eCongnition’s multi-scale segmentation.

  19. Membership determination of open clusters based on a spectral clustering method

    Science.gov (United States)

    Gao, Xin-Hua

    2018-06-01

    We present a spectral clustering (SC) method aimed at segregating reliable members of open clusters in multi-dimensional space. The SC method is a non-parametric clustering technique that performs cluster division using eigenvectors of the similarity matrix; no prior knowledge of the clusters is required. This method is more flexible in dealing with multi-dimensional data compared to other methods of membership determination. We use this method to segregate the cluster members of five open clusters (Hyades, Coma Ber, Pleiades, Praesepe, and NGC 188) in five-dimensional space; fairly clean cluster members are obtained. We find that the SC method can capture a small number of cluster members (weak signal) from a large number of field stars (heavy noise). Based on these cluster members, we compute the mean proper motions and distances for the Hyades, Coma Ber, Pleiades, and Praesepe clusters, and our results are in general quite consistent with the results derived by other authors. The test results indicate that the SC method is highly suitable for segregating cluster members of open clusters based on high-precision multi-dimensional astrometric data such as Gaia data.

  20. Effect of Soil Use and Coverage on the Spectral Response of an Oxisol in the VIS-NIR-MIR Region

    Directory of Open Access Journals (Sweden)

    Javier M. Martín-López

    2017-02-01

    Full Text Available In this study, the spectral responses obtained from a Typic Red Hapludox (oxisol were analyzed under different uses and occupations: Ficus elastica cultivation, Citrus + Arachis association cultivation, transitional crops, forest, Mangifera indica, Anacardium occidentale, Elaeis guineensis (18 years, Brachiaria decumbens, Brachiaria brizantha, and Musa × paradisiaca + Zea mays at the La Libertad Research Center in the department of Meta in Colombia (4°04′ North latitude, 73°30′ West longitude, 330 MAMSL. Sampling was performed with four random replicates of the horizon A and B to determine the contents of organic carbon (CO, pH, exchangeable acidity (Ac. I, cation exchange capacity (Cc, P, Ca, Mg, K, Na, sand, lime, and clay and spectral responses were obtained in the visible band (VIS, near infrared (NIR, and infrared (MIR for each sample under laboratory conditions. A comparison was made between the obtained spectra, determining the main changes in soil properties due to their use and coverage. Variation of soil characteristics such as color, organic carbon content, presence of ferrous compounds, sand, silt, and clay content and mineralogy allow the identification of the main spectral changes of soils, demonstrating the importance of the use of reflectance spectroscopy as a tool of comparison and estimation between physical-chemical properties of the soils.

  1. 3D airborne EM modeling based on the spectral-element time-domain (SETD) method

    Science.gov (United States)

    Cao, X.; Yin, C.; Huang, X.; Liu, Y.; Zhang, B., Sr.; Cai, J.; Liu, L.

    2017-12-01

    In the field of 3D airborne electromagnetic (AEM) modeling, both finite-difference time-domain (FDTD) method and finite-element time-domain (FETD) method have limitations that FDTD method depends too much on the grids and time steps, while FETD requires large number of grids for complex structures. We propose a time-domain spectral-element (SETD) method based on GLL interpolation basis functions for spatial discretization and Backward Euler (BE) technique for time discretization. The spectral-element method is based on a weighted residual technique with polynomials as vector basis functions. It can contribute to an accurate result by increasing the order of polynomials and suppressing spurious solution. BE method is a stable tine discretization technique that has no limitation on time steps and can guarantee a higher accuracy during the iteration process. To minimize the non-zero number of sparse matrix and obtain a diagonal mass matrix, we apply the reduced order integral technique. A direct solver with its speed independent of the condition number is adopted for quickly solving the large-scale sparse linear equations system. To check the accuracy of our SETD algorithm, we compare our results with semi-analytical solutions for a three-layered earth model within the time lapse 10-6-10-2s for different physical meshes and SE orders. The results show that the relative errors for magnetic field B and magnetic induction are both around 3-5%. Further we calculate AEM responses for an AEM system over a 3D earth model in Figure 1. From numerical experiments for both 1D and 3D model, we draw the conclusions that: 1) SETD can deliver an accurate results for both dB/dt and B; 2) increasing SE order improves the modeling accuracy for early to middle time channels when the EM field diffuses fast so the high-order SE can model the detailed variation; 3) at very late time channels, increasing SE order has little improvement on modeling accuracy, but the time interval plays

  2. Estimation of spectral solar radiation based on global insolation and characteristics of spectral solar radiation on a tilt surface; Zenten nissharyo ni motozuku zenten nissha supekutoru no suitei to keishamen bunko tokusei

    Energy Technology Data Exchange (ETDEWEB)

    Baba, H; Kanayama, K; Endo, N; Koromohara, K; Takayama, H [Kitami Institute of Technology, Hokkaido (Japan)

    1996-10-27

    Use of global insolation for estimating the corresponding spectral distribution is proposed. Measurements of global insolation spectrum throughout a year were compiled for clear days and cloudy days, ranked by 100W/m{sup 2}, for the clarification of spectral distribution. Global insolation quantity for a clear day was subject mainly to sun elevation. The global insolation spectral distribution with the sun elevation not lower than 15{degree} was similar to Bird`s model. Under the cloudy sky, energy density was lower in the region of wavelengths longer than the peak wavelength of 0.46{mu}m, and the distribution curve was sharper than that under the clear sky. Values given by Bird`s model were larger than measured values in the wavelength range of 0.6-1.8{mu}m, which was attributed to absorption by vapor. From the standard spectral distribution charts for the clear sky and cloudy sky, and from the dimensionless spectral distributions obtained by dividing them by the peak values, spectral distributions could be estimated of insolation quantities for the clear sky, cloudy sky, etc. As for the characteristics of spectral solar radiation on a tilt surface obtained from Bird`s model, they agreed with actually measured values at an angle of inclination of 60{degree} or smaller. 6 refs., 10 figs., 1 tab.

  3. Spectral ellipsometry of nanodiamond composite

    International Nuclear Information System (INIS)

    Yastrebov, S.G.; Ivanov-Omskij, V.I.; Gordeev, S.K.; Garriga, M.; Alonso, I.A.

    2006-01-01

    Methods of spectral ellipsometry were applied for analysis of optical properties of nanodiamond based composite in spectral region 1.4-5 eV. The nanocomposite was synthesized by molding of ultradispersed nanodiamond powder in the course of heterogeneous chemical reaction of decomposition of methane, forming pyrocarbon interconnecting nanodiamond grains. The energy of σ + π plasmon of pyrocarbon component of nanodiamond composite was restored which proves to be ∼ 24 eV; using this value, an estimation was done of pyrocarbon matrix density, which occurs to be 2 g/cm 3 [ru

  4. A k-mer-based barcode DNA classification methodology based on spectral representation and a neural gas network.

    Science.gov (United States)

    Fiannaca, Antonino; La Rosa, Massimo; Rizzo, Riccardo; Urso, Alfonso

    2015-07-01

    In this paper, an alignment-free method for DNA barcode classification that is based on both a spectral representation and a neural gas network for unsupervised clustering is proposed. In the proposed methodology, distinctive words are identified from a spectral representation of DNA sequences. A taxonomic classification of the DNA sequence is then performed using the sequence signature, i.e., the smallest set of k-mers that can assign a DNA sequence to its proper taxonomic category. Experiments were then performed to compare our method with other supervised machine learning classification algorithms, such as support vector machine, random forest, ripper, naïve Bayes, ridor, and classification tree, which also consider short DNA sequence fragments of 200 and 300 base pairs (bp). The experimental tests were conducted over 10 real barcode datasets belonging to different animal species, which were provided by the on-line resource "Barcode of Life Database". The experimental results showed that our k-mer-based approach is directly comparable, in terms of accuracy, recall and precision metrics, with the other classifiers when considering full-length sequences. In addition, we demonstrate the robustness of our method when a classification is performed task with a set of short DNA sequences that were randomly extracted from the original data. For example, the proposed method can reach the accuracy of 64.8% at the species level with 200-bp fragments. Under the same conditions, the best other classifier (random forest) reaches the accuracy of 20.9%. Our results indicate that we obtained a clear improvement over the other classifiers for the study of short DNA barcode sequence fragments. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Broadband spectral shaping in regenerative amplifier based on modified polarization-encoded chirped pulse amplification

    Science.gov (United States)

    Wang, Xinliang; Lu, Xiaoming; Liu, Yanqi; Xu, Yi; Wang, Cheng; Li, Shuai; Yu, Linpeng; Liu, Xingyan; Liu, Keyang; Xu, Rongjie; Leng, Yuxin

    2018-06-01

    We present an intra-cavity spectral shaping method to suppress the spectral narrowing in a Ti:sapphire (Ti:Sa) regenerative amplifier. The spectral shaping is realized by manipulating the stored energies of two Ti:Sa crystals with orthogonal c-axes, changing the length of a quartz plate, and rotating a broadband achromatic half-wave plate. Using this method, in our proof-of-concept experiment, an 84-nm-(FWHM)-broadband amplified pulse with an energy gain larger than 106 is obtained, which supports a 17.8 fs Fourier-transform-limited pulse duration. The pulse is compressed to 18.9 fs.

  6. Difference equations having bases with powerlike growth which are perturbed by a spectral parameter

    International Nuclear Information System (INIS)

    Tulyakov, Dmitrii N

    2009-01-01

    The asymptotic behaviour of solutions with powerlike growth of recurrence relations with a spectral parameter is investigated. A class of recurrence relations in which all basis solutions have powerlike growth is introduced. Recurrence relations in this class are linearly perturbed by a spectral parameter; for solutions of the new recurrence relations asymptotic formulae are obtained which are uniform with respect to the spectral parameter ranging within appropriate bounds. The theorems obtained are used for deriving new local asymptotic formulae for orthogonal and multiple orthogonal polynomials in a neighbourhood of the end-points of the support of the orthogonality weights. Bibliography: 14 titles.

  7. Landsat-based trend analysis of lake dynamics across northern permafrost regions

    Science.gov (United States)

    Nitze, Ingmar; Grosse, Guido; Jones, Benjamin M.; Arp, Christopher D.; Ulrich, Mathias; Federov, Alexander; Veremeeva, Alexandra

    2017-01-01

    Lakes are a ubiquitous landscape feature in northern permafrost regions. They have a strong impact on carbon, energy and water fluxes and can be quite responsive to climate change. The monitoring of lake change in northern high latitudes, at a sufficiently accurate spatial and temporal resolution, is crucial for understanding the underlying processes driving lake change. To date, lake change studies in permafrost regions were based on a variety of different sources, image acquisition periods and single snapshots, and localized analysis, which hinders the comparison of different regions. Here we present, a methodology based on machine-learning based classification of robust trends of multi-spectral indices of Landsat data (TM,ETM+, OLI) and object-based lake detection, to analyze and compare the individual, local and regional lake dynamics of four different study sites (Alaska North Slope, Western Alaska, Central Yakutia, Kolyma Lowland) in the northern permafrost zone from 1999 to 2014. Regional patterns of lake area change on the Alaska North Slope (-0.69%), Western Alaska (-2.82%), and Kolyma Lowland (-0.51%) largely include increases due to thermokarst lake expansion, but more dominant lake area losses due to catastrophic lake drainage events. In contrast, Central Yakutia showed a remarkable increase in lake area of 48.48%, likely resulting from warmer and wetter climate conditions over the latter half of the study period. Within all study regions, variability in lake dynamics was associated with differences in permafrost characteristics, landscape position (i.e. upland vs. lowland), and surface geology. With the global availability of Landsat data and a consistent methodology for processing the input data derived from robust trends of multi-spectral indices, we demonstrate a transferability, scalability and consistency of lake change analysis within the northern permafrost region.

  8. Dispersive heterodyne probing method for laser frequency stabilization based on spectral hole burning in rare-earth doped crystals

    DEFF Research Database (Denmark)

    Gobron, Olivier; Jung, K.; Galland, N.

    2017-01-01

    Frequency-locking a laser to a spectral hole in rare-earth doped crystals at cryogenic temperature has been shown to be a promising alternative to the use of high finesse Fabry-Perot cavities when seeking a very high short term stability laser (M. J. Thorpe et al., Nature Photonics 5, 688 (2011......)). We demonstrate here a novel technique for achieving such stabilization, based on generating a heterodyne beat-note between a master laser and a slave laser whose dephasing caused by propagation near a spectral hole generate the error signal of the frequency lock. The master laser is far detuned from...

  9. Comparison of SVM RBF-NN and DT for crop and weed identification based on spectral measurement over corn fields

    Science.gov (United States)

    It is important to find an appropriate pattern-recognition method for in-field plant identification based on spectral measurement in order to classify the crop and weeds accurately. In this study, the method of Support Vector Machine (SVM) was evaluated and compared with two other methods, Decision ...

  10. Characterization of Spectral Magnification based on Four-Wave Mixing in Nonlinear Fibre for Advanced Modulation Formats

    DEFF Research Database (Denmark)

    Lillieholm, Mads; Corcoran, B.; Galili, Michael

    2017-01-01

    We characterize the performance of 4× spectral magnification based on four-wave mixing in optimized nonlinear fibres, for 4/8/16-QAM formats, and report >19-nm operational bandwidth. Predominantly OSNR penalties of ~1 dB per bit/QAM-symbol from aberrations non-intrinsic to time lenses are observed....

  11. Seismic spectral decomposition and analysis based on Wigner–Ville distribution for sandstone reservoir characterization in West Sichuan depression

    International Nuclear Information System (INIS)

    Wu, Xiaoyang; Liu, Tianyou

    2010-01-01

    Reflections from a hydrocarbon-saturated zone are generally expected to have a tendency to be low frequency. Previous work has shown the application of seismic spectral decomposition for low-frequency shadow detection. In this paper, we further analyse the characteristics of spectral amplitude in fractured sandstone reservoirs with different fluid saturations using the Wigner–Ville distribution (WVD)-based method. We give a description of the geometric structure of cross-terms due to the bilinear nature of WVD and eliminate cross-terms using smoothed pseudo-WVD (SPWVD) with time- and frequency-independent Gaussian kernels as smoothing windows. SPWVD is finally applied to seismic data from West Sichuan depression. We focus our study on the comparison of SPWVD spectral amplitudes resulting from different fluid contents. It shows that prolific gas reservoirs feature higher peak spectral amplitude at higher peak frequency, which attenuate faster than low-quality gas reservoirs and dry or wet reservoirs. This can be regarded as a spectral attenuation signature for future exploration in the study area

  12. Spectral-ratio radon background correction method in airborne γ-ray spectrometry based on compton scattering deduction

    International Nuclear Information System (INIS)

    Gu Yi; Xiong Shengqing; Zhou Jianxin; Fan Zhengguo; Ge Liangquan

    2014-01-01

    γ-ray released by the radon daughter has severe impact on airborne γ-ray spectrometry. The spectral-ratio method is one of the best mathematical methods for radon background deduction in airborne γ-ray spectrometry. In this paper, an advanced spectral-ratio method was proposed which deducts Compton scattering ray by the fast Fourier transform rather than tripping ratios, the relationship between survey height and correction coefficient of the advanced spectral-ratio radon background correction method was studied, the advanced spectral-ratio radon background correction mathematic model was established, and the ground saturation model calibrating technology for correction coefficient was proposed. As for the advanced spectral-ratio radon background correction method, its applicability and correction efficiency are improved, and the application cost is saved. Furthermore, it can prevent the physical meaning lost and avoid the possible errors caused by matrix computation and mathematical fitting based on spectrum shape which is applied in traditional correction coefficient. (authors)

  13. Multilayer photosensitive structures based on porous silicon and rare-earth-element compounds: Study of spectral characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Kirsanov, N. Yu.; Latukhina, N. V., E-mail: natalat@yandex.ru; Lizunkova, D. A.; Rogozhina, G. A. [Samara National Research University (Russian Federation); Stepikhova, M. V. [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation)

    2017-03-15

    The spectral characteristics of the specular reflectance, photosensitivity, and photoluminescence (PL) of multilayer structures based on porous silicon with rare-earth-element (REE) ions are investigated. It is shown that the photosensitivity of these structures in the wavelength range of 0.4–1.0 μm is higher than in structures free of REEs. The structures with Er{sup 3+} ions exhibit a luminescence response at room temperature in the spectral range from 1.1 to 1.7 μm. The PL spectrum of the erbium impurity is characterized by a fine line structure, which is determined by the splitting of the {sup 4}I{sub 15/2} multiplet of the Er{sup 3+} ion. It is shown that the structures with a porous layer on the working surface have a much lower reflectance in the entire spectral range under study (0.2–1.0 μm).

  14. Manifold learning based feature extraction for classification of hyper-spectral data

    CSIR Research Space (South Africa)

    Lunga, D

    2013-08-01

    Full Text Available Advances in hyperspectral sensing provide new capability for characterizing spectral signatures in a wide range of physical and biological systems, while inspiring new methods for extracting information from these data. Hyperspectral image data...

  15. Filter Selection for Optimizing the Spectral Sensitivity of Broadband Multispectral Cameras Based on Maximum Linear Independence.

    Science.gov (United States)

    Li, Sui-Xian

    2018-05-07

    Previous research has shown that the effectiveness of selecting filter sets from among a large set of commercial broadband filters by a vector analysis method based on maximum linear independence (MLI). However, the traditional MLI approach is suboptimal due to the need to predefine the first filter of the selected filter set to be the maximum ℓ₂ norm among all available filters. An exhaustive imaging simulation with every single filter serving as the first filter is conducted to investigate the features of the most competent filter set. From the simulation, the characteristics of the most competent filter set are discovered. Besides minimization of the condition number, the geometric features of the best-performed filter set comprise a distinct transmittance peak along the wavelength axis of the first filter, a generally uniform distribution for the peaks of the filters and substantial overlaps of the transmittance curves of the adjacent filters. Therefore, the best-performed filter sets can be recognized intuitively by simple vector analysis and just a few experimental verifications. A practical two-step framework for selecting optimal filter set is recommended, which guarantees a significant enhancement of the performance of the systems. This work should be useful for optimizing the spectral sensitivity of broadband multispectral imaging sensors.

  16. GPU-Based High-performance Imaging for Mingantu Spectral RadioHeliograph

    Science.gov (United States)

    Mei, Ying; Wang, Feng; Wang, Wei; Chen, Linjie; Liu, Yingbo; Deng, Hui; Dai, Wei; Liu, Cuiyin; Yan, Yihua

    2018-01-01

    As a dedicated solar radio interferometer, the MingantU SpEctral RadioHeliograph (MUSER) generates massive observational data in the frequency range of 400 MHz-15 GHz. High-performance imaging forms a significantly important aspect of MUSER’s massive data processing requirements. In this study, we implement a practical high-performance imaging pipeline for MUSER data processing. At first, the specifications of the MUSER are introduced and its imaging requirements are analyzed. Referring to the most commonly used radio astronomy software such as CASA and MIRIAD, we then implement a high-performance imaging pipeline based on the Graphics Processing Unit technology with respect to the current operational status of the MUSER. A series of critical algorithms and their pseudo codes, i.e., detection of the solar disk and sky brightness, automatic centering of the solar disk and estimation of the number of iterations for clean algorithms, are proposed in detail. The preliminary experimental results indicate that the proposed imaging approach significantly increases the processing performance of MUSER and generates images with high-quality, which can meet the requirements of the MUSER data processing. Supported by the National Key Research and Development Program of China (2016YFE0100300), the Joint Research Fund in Astronomy (No. U1531132, U1631129, U1231205) under cooperative agreement between the National Natural Science Foundation of China (NSFC) and the Chinese Academy of Sciences (CAS), the National Natural Science Foundation of China (Nos. 11403009 and 11463003).

  17. Analysis of China's real estate prices and macroeconomy based on evolutionary co-spectral method

    Directory of Open Access Journals (Sweden)

    Juan Li

    2015-04-01

    Full Text Available Purpose: This paper investigates the dynamic interaction between the real estate market and the macroeconomic environment of China by use of dynamic coherence function based on co-spectral analysis. Design/methodology/approach: Through a theoretical perspective, the dynamic interrelationship among economic variables at different time intervals (both long and short terms is analyzed. Findings: The empirical results show that China’s real estate market features a high coherence with the change of the long-term interest rate, employment rate and money supply, while there is a moderate coherence between the real estate market and the inflation rate and economic growth rate, and the coherence between the short-term rate of interest and the real estate market is the lowest. Research implications: Previous researches have some shortcomings. They do not consider the dependence between nonlinear series, but the latter is crucial to avoid the deviation of results. In this paper, we proposed a new method of experience to overcome these shortcomings. Originality/value: The paper provides a reasonable explanation accordingly to different coherences between the real estate market and the macroeconomic variables.

  18. Filter Selection for Optimizing the Spectral Sensitivity of Broadband Multispectral Cameras Based on Maximum Linear Independence

    Directory of Open Access Journals (Sweden)

    Sui-Xian Li

    2018-05-01

    Full Text Available Previous research has shown that the effectiveness of selecting filter sets from among a large set of commercial broadband filters by a vector analysis method based on maximum linear independence (MLI. However, the traditional MLI approach is suboptimal due to the need to predefine the first filter of the selected filter set to be the maximum ℓ2 norm among all available filters. An exhaustive imaging simulation with every single filter serving as the first filter is conducted to investigate the features of the most competent filter set. From the simulation, the characteristics of the most competent filter set are discovered. Besides minimization of the condition number, the geometric features of the best-performed filter set comprise a distinct transmittance peak along the wavelength axis of the first filter, a generally uniform distribution for the peaks of the filters and substantial overlaps of the transmittance curves of the adjacent filters. Therefore, the best-performed filter sets can be recognized intuitively by simple vector analysis and just a few experimental verifications. A practical two-step framework for selecting optimal filter set is recommended, which guarantees a significant enhancement of the performance of the systems. This work should be useful for optimizing the spectral sensitivity of broadband multispectral imaging sensors.

  19. Spontaneous Rayleigh-Brillouin scattering spectral analysis based on the Wiener filter

    Directory of Open Access Journals (Sweden)

    Tao Wu

    2018-01-01

    Full Text Available In this paper, a spontaneous Rayleigh-Brillouin scattering spectrometer is developed to measure the gaseous spontaneous Rayleigh-Brillouin scattering profiles over the pressure range from 1 to 5 atm for a wavelength of 532nm at a constant room temperature of 296K and a 90o scattering angle. In order to make a direct comparison between the experimentally obtained spectrum and the theoretical spectrum calculated from the Tenti S6 model, the measured spontaneous Rayleigh-Brillouin scattering signal is deconvolved by the Wiener filtering. The purpose is to remove the effect on the spectrum by the transmission function of the Fabry-Perrot scanning interferometer. The results of the comparison show that the deconvolved spectra are consistent with the theoretical spectra calculated from the Tenti S6 model, and thus confirm that the deconvolution based on the Wiener filter is able to process the measured spectra and improve the spectral resolution. Some factors that influence the accuracy of deconvolution are analyzed and discussed. At the same time, another comparison between the raw experimentally obtained spectra and the theoretical spectra calculated by convolving the Tenti S6 model with instrument function of the measurement system is performed in the same experimental condition. The results of the two comparisons show that, compared with the raw experimentally obtained spectrum, the deconvolved spectrum matches the theoretically calculated spectrum more accurately under lower pressure (≤2atm than under relative higher pressure (>2atm.

  20. Spectral Analysis Method of Plastic Scintillator-based Radiation Detector against Nuclear/Radiological Terrorism

    International Nuclear Information System (INIS)

    Kwak, Sung-Woo; Yoo, Ho-Sik; Jang, Sung Soon; Kim, Jung-Soo; Yoon, Wan-Ki

    2008-01-01

    In these days, the threats relating to nuclear or radioactive materials have become a matter of internationally increased grave concern. A plastic scintillation detector in radiation portal monitoring (RPM) application has been used to detect radioactive sources in steel scrap entering reprocessing facilities, and to detect illicit transport of radioactive material across border ports-of-entry. The detection systems for RPM application usually are large and can not easily be moved to a different location. For some situations, an inconspicuous and mobile system for the radioactive or nuclear material during road transport is needed. The mobile radiation detection system has employed a NaI- based radiation detector to detect and identify the material hidden in vehicle. There are some operational constraints - short measuring time, weak activity due to heavy shield of illegal source, long distance - of inspection system in such nuclear security applications. Due to these constraints, large area sensor is required to maximize its sensitivity. Large NaI material, however, is extremely expensive. In designing a radiation detector for prevention of illicit trafficking of nuclear or radioactive materials, the trade-off should be carefully optimized between performance and cost in order to achieve cost-effective inspection system. For the cost-effective mobile radiation detection system, this paper describes new spectral analysis method to use the crude spectroscopic information available from a plastic detector to discriminate other man-made radiation source from NORM

  1. A Gaussian process and derivative spectral-based algorithm for red blood cell segmentation

    Science.gov (United States)

    Xue, Yingying; Wang, Jianbiao; Zhou, Mei; Hou, Xiyue; Li, Qingli; Liu, Hongying; Wang, Yiting

    2017-07-01

    As an imaging technology used in remote sensing, hyperspectral imaging can provide more information than traditional optical imaging of blood cells. In this paper, an AOTF based microscopic hyperspectral imaging system is used to capture hyperspectral images of blood cells. In order to achieve the segmentation of red blood cells, Gaussian process using squared exponential kernel function is applied first after the data preprocessing to make the preliminary segmentation. The derivative spectrum with spectral angle mapping algorithm is then applied to the original image to segment the boundary of cells, and using the boundary to cut out cells obtained from the Gaussian process to separated adjacent cells. Then the morphological processing method including closing, erosion and dilation is applied so as to keep adjacent cells apart, and by applying median filtering to remove noise points and filling holes inside the cell, the final segmentation result can be obtained. The experimental results show that this method appears better segmentation effect on human red blood cells.

  2. A new physics-based method for detecting weak nuclear signals via spectral decomposition

    International Nuclear Information System (INIS)

    Chan, Kung-Sik; Li, Jinzheng; Eichinger, William; Bai, Erwei

    2012-01-01

    We propose a new physics-based method to determine the presence of the spectral signature of one or more nuclides from a poorly resolved spectra with weak signatures. The method is different from traditional methods that rely primarily on peak finding algorithms. The new approach considers each of the signatures in the library to be a linear combination of subspectra. These subspectra are obtained by assuming a signature consisting of just one of the unique gamma rays emitted by the nuclei. We propose a Poisson regression model for deducing which nuclei are present in the observed spectrum. In recognition that a radiation source generally comprises few nuclear materials, the underlying Poisson model is sparse, i.e. most of the regression coefficients are zero (positive coefficients correspond to the presence of nuclear materials). We develop an iterative algorithm for a penalized likelihood estimation that prompts sparsity. We illustrate the efficacy of the proposed method by simulations using a variety of poorly resolved, low signal-to-noise ratio (SNR) situations, which show that the proposed approach enjoys excellent empirical performance even with SNR as low as to -15 db.

  3. Coordination chemistry of oxovanadium(V) complexes with active Schiff bases: synthetic, spectral, and antimicrobial approach

    International Nuclear Information System (INIS)

    Garg, R; Fahmi, N.; Singh, R.V.

    2007-01-01

    The Schiff bases, 3-(indolin-2-one)hydrazinecarbothioamide, 3-(indolin-2-one)hydrazinecarboxamide, 5,6-dimethyl-3-(indolin-2-one)hydrazinecarbothioamide, and 5,6-dimethyl-3-(indolin-2-one)hydrazinecarboxamide, have been synthesized by the condensation of 1H-indol-2,3-dione and 5,6-dimethyl-1H-indol-2,3-dione with the corresponding hydrazinecarbothioamide and hydrazinecarboxamide, respectively. The complexes of oxovanadium and ligands have been characterized by elemental analyses, melting points, conductance measurements, molecular weight determinations, and IR, 1 H NMR and UV spectral studies. These studies showed that the ligands coordinated to the oxovanadium in a monobasic bidentate fashion through oxygen or sulfur and the nitrogen donor system. Thus, penta- and hexa coordinated environment around the vanadium atom has been proposed. All the complexes and their parent organic moieties have been screened for their biological activity on several pathogenic fungi and bacteria and were found to possess appreciable fungicidal and bactericidal properties [ru

  4. Carded Tow Real-Time Color Assessment: A Spectral Camera-Based System

    Directory of Open Access Journals (Sweden)

    Rocco Furferi

    2016-08-01

    Full Text Available One of the most important parameters to be controlled during the production of textile yarns obtained by mixing pre-colored fibers, is the color correspondence between the manufactured yarn and a given reference, usually provided by a designer or a customer. Obtaining yarns from raw pre-colored fibers is a complex manufacturing process entailing a number of steps such as laboratory sampling, color recipe corrections, blowing, carding and spinning. Carding process is the one devoted to transform a “fuzzy mass” of tufted fibers into a regular mass of untwisted fibers, named “tow”. During this process, unfortunately, the correspondence between the color of the tow and the target one cannot be assured, thus leading to yarns whose color differs from the one used for reference. To solve this issue, the main aim of this work is to provide a system able to perform a spectral camera-based real-time measurement of a carded tow, to assess its color correspondence with a reference carded fabric and, at the same time, to monitor the overall quality of the tow during the carding process. Tested against a number of differently colored carded fabrics, the proposed system proved its effectiveness in reliably assessing color correspondence in real-time.

  5. PARALLEL IMPLEMENTATION OF MORPHOLOGICAL PROFILE BASED SPECTRAL-SPATIAL CLASSIFICATION SCHEME FOR HYPERSPECTRAL IMAGERY

    Directory of Open Access Journals (Sweden)

    B. Kumar

    2016-06-01

    Full Text Available Extended morphological profile (EMP is a good technique for extracting spectral-spatial information from the images but large size of hyperspectral images is an important concern for creating EMPs. However, with the availability of modern multi-core processors and commodity parallel processing systems like graphics processing units (GPUs at desktop level, parallel computing provides a viable option to significantly accelerate execution of such computations. In this paper, parallel implementation of an EMP based spectralspatial classification method for hyperspectral imagery is presented. The parallel implementation is done both on multi-core CPU and GPU. The impact of parallelization on speed up and classification accuracy is analyzed. For GPU, the implementation is done in compute unified device architecture (CUDA C. The experiments are carried out on two well-known hyperspectral images. It is observed from the experimental results that GPU implementation provides a speed up of about 7 times, while parallel implementation on multi-core CPU resulted in speed up of about 3 times. It is also observed that parallel implementation has no adverse impact on the classification accuracy.

  6. [Design of plant leaf bionic camouflage materials based on spectral analysis].

    Science.gov (United States)

    Yang, Yu-Jie; Liu, Zhi-Ming; Hu, Bi-Ru; Wu, Wen-Jian

    2011-06-01

    The influence of structure parameters and contents of plant leaves on their reflectance spectra was analyzed using the PROSPECT model. The result showed that the bionic camouflage materials should be provided with coarse surface and spongy inner structure, the refractive index of main content must be close to that of plant leaves, the contents of materials should contain chlorophyll and water, and the content of C-H bond must be strictly controlled. Based on the analysis above, a novel camouflage material, which was constituted by coarse transparent waterproof surface, chlorophyll, water and spongy material, was designed. The result of verifiable experiment showed that the reflectance spectra of camouflage material exhibited the same characteristics as those of plant leaves. The similarity coefficient of reflectance spectrum of the camouflage material and camphor leaves was 0.988 1, and the characteristics of camouflage material did not change after sunlight treatment for three months. The bionic camouflage material, who exhibited a high spectral similarity with plant leaves and a good weather resistance, will be an available method for reconnaissance of hyperspectral imaging hopefully.

  7. Research on marine and freshwater fish identification model based on hyper-spectral imaging technology

    Science.gov (United States)

    Fu, Yan; Guo, Pei-yuan; Xiang, Ling-zi; Bao, Man; Chen, Xing-hai

    2013-08-01

    With the gradually mature of hyper spectral image technology, the application of the meat nondestructive detection and recognition has become one of the current research focuses. This paper for the study of marine and freshwater fish by the pre-processing and feature extraction of the collected spectral curve data, combined with BP network structure and LVQ network structure, a predictive model of hyper spectral image data of marine and freshwater fish has been initially established and finally realized the qualitative analysis and identification of marine and freshwater fish quality. The results of this study show that hyper spectral imaging technology combined with the BP and LVQ Artificial Neural Network Model can be used for the identification of marine and freshwater fish detection. Hyper-spectral data acquisition can be carried out without any pretreatment of the samples, thus hyper-spectral imaging technique is the lossless, high- accuracy and rapid detection method for quality of fish. In this study, only 30 samples are used for the exploratory qualitative identification of research, although the ideal study results are achieved, we will further increase the sample capacity to take the analysis of quantitative identification and verify the feasibility of this theory.

  8. 7-cell core hollow-core photonic crystal fibers with low loss in the spectral region around 2 mu m

    DEFF Research Database (Denmark)

    Lyngsøe, Jens Kristian; Mangan, B.J.; Jakobsen, C.

    2009-01-01

    Several 7 cell core hollow-core photonic crystal fibers with bandgaps in the spectral range of 1.4 μm to 2.3 μm have been fabricated. The transmission loss follows the ≈ λ−3 dependency previously reported, with a minimum measured loss of 9.5 dB/km at 1.99 μm. One fiber with a transmission loss...... of 26 dB/km at 2.3 μm is reported, which is significantly lower than the transmission loss of solid silica fibers at this wavelength....

  9. Contrast-enhanced spectral mammography based on a photon-counting detector: quantitative accuracy and radiation dose

    Science.gov (United States)

    Lee, Seungwan; Kang, Sooncheol; Eom, Jisoo

    2017-03-01

    Contrast-enhanced mammography has been used to demonstrate functional information about a breast tumor by injecting contrast agents. However, a conventional technique with a single exposure degrades the efficiency of tumor detection due to structure overlapping. Dual-energy techniques with energy-integrating detectors (EIDs) also cause an increase of radiation dose and an inaccuracy of material decomposition due to the limitations of EIDs. On the other hands, spectral mammography with photon-counting detectors (PCDs) is able to resolve the issues induced by the conventional technique and EIDs using their energy-discrimination capabilities. In this study, the contrast-enhanced spectral mammography based on a PCD was implemented by using a polychromatic dual-energy model, and the proposed technique was compared with the dual-energy technique with an EID in terms of quantitative accuracy and radiation dose. The results showed that the proposed technique improved the quantitative accuracy as well as reduced radiation dose comparing to the dual-energy technique with an EID. The quantitative accuracy of the contrast-enhanced spectral mammography based on a PCD was slightly improved as a function of radiation dose. Therefore, the contrast-enhanced spectral mammography based on a PCD is able to provide useful information for detecting breast tumors and improving diagnostic accuracy.

  10. Estimating Pasture Quality of Fresh Vegetation Based on Spectral Slope of Mixed Data of Dry and Fresh Vegetation—Method Development

    Directory of Open Access Journals (Sweden)

    Rachel Lugassi

    2015-06-01

    Full Text Available The main objective of the present study was to apply a slope-based spectral method to both dry and fresh pasture vegetation. Differences in eight spectral ranges were identified across the near infrared-shortwave infrared (NIR-SWIR that were indicative of changes in chemical properties. Slopes across these ranges were calculated and a partial least squares (PLS analytical model was constructed for the slopes vs. crude protein (CP and neutral detergent fiber (NDF contents. Different datasets with different numbers of fresh/dry samples were constructed to predict CP and NDF contents. When using a mixed-sample dataset with dry-to-fresh ratios of 85%:15% and 75%:25%, the correlations of CP (R2 = 0.95, in both and NDF (R2 = 0.84 and 0.82, respectively were almost as high as when using only dry samples (0.97 and 0.85, respectively. Furthermore, satisfactory correlations were obtained with a dry-to-fresh ratio of 50%:50% for CP (R2 = 0.92. The results of our study are especially encouraging because CP and NDF contents could be predicted even though some of the selected spectral regions were directly affected by atmospheric water vapor or water in the plants.

  11. Chromospheric polarimetry through multiline observations of the 850-nm spectral region - II. A magnetic flux tube scenario

    Science.gov (United States)

    Quintero Noda, C.; Kato, Y.; Katsukawa, Y.; Oba, T.; de la Cruz Rodríguez, J.; Carlsson, M.; Shimizu, T.; Orozco Suárez, D.; Ruiz Cobo, B.; Kubo, M.; Anan, T.; Ichimoto, K.; Suematsu, Y.

    2017-11-01

    In this publication, we continue the work started in Quintero Noda et al., examining this time a numerical simulation of a magnetic flux tube concentration. Our goal is to study if the physical phenomena that take place in it, in particular, the magnetic pumping, leaves a specific imprint on the examined spectral lines. We find that the profiles from the interior of the flux tube are periodically doppler shifted following an oscillation pattern that is also reflected in the amplitude of the circular polarization signals. In addition, we analyse the properties of the Stokes profiles at the edges of the flux tube discovering the presence of linear polarization signals for the Ca II lines, although they are weak with an amplitude around 0.5 per cent of the continuum intensity. Finally, we compute the response functions to perturbations in the longitudinal field, and we estimate the field strength using the weak-field approximation. Our results indicate that the height of formation of the spectral lines changes during the magnetic pumping process, which makes the interpretation of the inferred magnetic field strength and its evolution more difficult. These results complement those from previous works, demonstrating the capabilities and limitations of the 850-nm spectrum for chromospheric Zeeman polarimetry in a very dynamic and complex atmosphere.

  12. Spectral Imaging Technology-Based Evaluation of Radiation Treatment Planning to Remove Contrast Agent Artifacts.

    Science.gov (United States)

    Yi-Qun, Xu; Wei, Liu; Xin-Ye, Ni

    2016-10-01

    This study employs dual-source computed tomography single-spectrum imaging to evaluate the effects of contrast agent artifact removal and the computational accuracy of radiotherapy treatment planning improvement. The phantom, including the contrast agent, was used in all experiments. The amounts of iodine in the contrast agent were 30, 15, 7.5, and 0.75 g/100 mL. Two images with different energy values were scanned and captured using dual-source computed tomography (80 and 140 kV). To obtain a fused image, 2 groups of images were processed using single-energy spectrum imaging technology. The Pinnacle planning system was used to measure the computed tomography values of the contrast agent and the surrounding phantom tissue. The difference between radiotherapy treatment planning based on 80 kV, 140 kV, and energy spectrum image was analyzed. For the image with high iodine concentration, the quality of the energy spectrum-fused image was the highest, followed by that of the 140-kV image. That of the 80-kV image was the worst. The difference in the radiotherapy treatment results among the 3 models was significant. When the concentration of iodine was 30 g/100 mL and the distance from the contrast agent at the dose measurement point was 1 cm, the deviation values (P) were 5.95% and 2.20% when image treatment planning was based on 80 and 140 kV, respectively. When the concentration of iodine was 15 g/100 mL, deviation values (P) were -2.64% and -1.69%. Dual-source computed tomography single-energy spectral imaging technology can remove contrast agent artifacts to improve the calculated dose accuracy in radiotherapy treatment planning. © The Author(s) 2015.

  13. Comparing Broad-Band and Red Edge-Based Spectral Vegetation Indices to Estimate Nitrogen Concentration of Crops Using Casi Data

    Science.gov (United States)

    Wang, Yanjie; Liao, Qinhong; Yang, Guijun; Feng, Haikuan; Yang, Xiaodong; Yue, Jibo

    2016-06-01

    In recent decades, many spectral vegetation indices (SVIs) have been proposed to estimate the leaf nitrogen concentration (LNC) of crops. However, most of these indices were based on the field hyperspectral reflectance. To test whether they can be used in aerial remote platform effectively, in this work a comparison of the sensitivity between several broad-band and red edge-based SVIs to LNC is investigated over different crop types. By using data from experimental LNC values over 4 different crop types and image data acquired using the Compact Airborne Spectrographic Imager (CASI) sensor, the extensive dataset allowed us to evaluate broad-band and red edge-based SVIs. The result indicated that NDVI performed the best among the selected SVIs while red edge-based SVIs didn't show the potential for estimating the LNC based on the CASI data due to the spectral resolution. In order to search for the optimal SVIs, the band combination algorithm has been used in this work. The best linear correlation against the experimental LNC dataset was obtained by combining the 626.20nm and 569.00nm wavebands. These wavelengths correspond to the maximal chlorophyll absorption and reflection position region, respectively, and are known to be sensitive to the physiological status of the plant. Then this linear relationship was applied to the CASI image for generating an LNC map, which can guide farmers in the accurate application of their N fertilization strategies.

  14. Spectral, biological screening of metal chelates of chalcone based Schiff bases of N-(3-aminopropyl) imidazole.

    Science.gov (United States)

    Kalanithi, M; Rajarajan, M; Tharmaraj, P; Sheela, C D

    2012-02-15

    Tridentate chelate complexes of Co(II), Ni(II), Cu(II) and Zn(II) have been synthesized from the chalcone based ligands 2-[1-(3-(1H-imidazol-1-yl)propylimino)-3-(phenylallyl)]phenol(HL(1)), 2-[1-(3-(1H-imidazol-1-yl)propylimino)-3-p-tolylallyl]phenol(HL(2)), 2-[1-(3-(1H-imidazol-1-yl)propylimino)-3-4-nitrophenylallyl]phenol(HL(3)). Microanalytical data, UV-vis spectrophotometric method, magnetic susceptibility measurements, IR, 1H NMR, Mass, and EPR techniques were used to characterize the structure of chelates. The electronic absorption spectra and magnetic susceptibility measurements suggest a distorted square planar geometry for the copper(II) ion. The other metal complexes show distorted tetrahedral geometry. The coordination of the ligands with metal(II) ions was further confirmed by solution fluorescence spectrum. The antimicrobial activity of the ligands and metal(II) complexes against the species Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, Bacillus subtilis, Candida albigans and Aspergillus niger has been carried out and compared. The electrochemical behavior of copper(II) complex is studied by cyclic voltammetry. Copyright © 2011 Elsevier B.V. All rights reserved.

  15. Application of full spectrum analysis technique for NaI(TI) based gamma ray spectral monitoring system

    International Nuclear Information System (INIS)

    Pant, Amar D.; Verma, Amit K.; Narayani, K.; Anilkumar, S.; Singh, Rajvir

    2016-01-01

    NaI(Tl) is commonly used for the gamma spectrometry analysis in laboratories. It continues to be the first choice for gamma spectrometry in many applications even today. Many gamma spectrometric methods are developed to experimentally determine activity of radionuclides in samples. Detectors used worldwide for gamma radiation monitoring are either GM based or scintillator based detector based on count rate. For radiation early warning systems radionuclide specific radiation monitoring methodology is required i.e. gamma ray spectrometry based environmental monitoring system. A computer program has been developed for gamma spectral monitoring by the use of full spectrum analysis (FSA). In this measured spectra are fitted using individual spectral components by least square fitting (LSF). The method is found very useful in situations, where radionuclide specific environmental radiation monitoring is required. The paper describes the details of the FSA procedure for the on line acquisition and analysis of gamma ray spectra from Nal(Tl) detectors

  16. Simulation for spectral response of solar-blind AlGaN based p-i-n photodiodes

    Science.gov (United States)

    Xue, Shiwei; Xu, Jintong; Li, Xiangyang

    2015-04-01

    In this article, we introduced how to build a physical model of refer to the device structure and parameters. Simulations for solar-blind AlGaN based p-i-n photodiodes spectral characteristics were conducted in use of Silvaco TCAD, where device structure and parameters are comprehensively considered. In simulation, the effects of polarization, Urbach tail, mobility, saturated velocities and lifetime in AlGaN device was considered. Especially, we focused on how the concentration-dependent Shockley-Read-Hall (SRH) recombination model affects simulation results. By simulating, we analyzed the effects in spectral response caused by TAUN0 and TAUP0, and got the values of TAUN0 and TAUP0 which can bring a result coincides with test results. After that, we changed their values and made the simulation results especially the part under 255 nm performed better. In conclusion, the spectral response between 200 nm and 320 nm of solar-blind AlGaN based p-i-n photodiodes were simulated and compared with test results. We also found that TAUN0 and TAUP0 have a large impact on spectral response of AlGaN material.

  17. WHY IS NON-THERMAL LINE BROADENING OF SPECTRAL LINES IN THE LOWER TRANSITION REGION OF THE SUN INDEPENDENT OF SPATIAL RESOLUTION?

    International Nuclear Information System (INIS)

    De Pontieu, B.; Martinez-Sykora, J.; McIntosh, S.; Peter, H.; Pereira, T. M. D.

    2015-01-01

    Spectral observations of the solar transition region (TR) and corona show broadening of spectral lines beyond what is expected from thermal and instrumental broadening. The remaining non-thermal broadening is significant (5–30 km s −1 ) and correlated with intensity. Here we study spectra of the TR Si iv 1403 Å line obtained at high resolution with the Interface Region Imaging Spectrograph (IRIS). We find that the large improvement in spatial resolution (0.″33) of IRIS compared to previous spectrographs (2″) does not resolve the non-thermal line broadening which, in most regions, remains at pre-IRIS levels of about 20 km s −1 . This invariance to spatial resolution indicates that the processes behind the broadening occur along the line-of-sight (LOS) and/or on spatial scales (perpendicular to the LOS) smaller than 250 km. Both effects appear to play a role. Comparison with IRIS chromospheric observations shows that, in regions where the LOS is more parallel to the field, magneto-acoustic shocks driven from below impact the TR and can lead to significant non-thermal line broadening. This scenario is supported by MHD simulations. While these do not show enough non-thermal line broadening, they do reproduce the long-known puzzling correlation between non-thermal line broadening and intensity. This correlation is caused by the shocks, but only if non-equilibrium ionization is taken into account. In regions where the LOS is more perpendicular to the field, the prevalence of small-scale twist is likely to play a significant role in explaining the invariance and correlation with intensity. (letters)

  18. The applicability of physical optics in the millimetre and sub-millimetre spectral region. Part I: The ray tracing with diffraction on facets method

    International Nuclear Information System (INIS)

    Baran, A.J.; Hesse, Evelyn; Sourdeval, Odran

    2017-01-01

    Future satellite missions, from 2022 onwards, will obtain near-global measurements of cirrus at microwave and sub-millimetre frequencies. To realise the potential of these observations, fast and accurate light-scattering methods are required to calculate scattered millimetre and sub-millimetre intensities from complex ice crystals. Here, the applicability of the ray tracing with diffraction on facets method (RTDF) in predicting the bulk scalar optical properties and phase functions of randomly oriented hexagonal ice columns and hexagonal ice aggregates at millimetre frequencies is investigated. The applicability of RTDF is shown to be acceptable down to size parameters of about 18, between the frequencies of 243 and 874 GHz. It is demonstrated that RTDF is generally well within about 10% of T-matrix solutions obtained for the scalar optical properties assuming hexagonal ice columns. Moreover, on replacing electromagnetic scalar optical property solutions obtained for the hexagonal ice aggregate with the RTDF counterparts at size parameter values of about 18 or greater, the bulk scalar optical properties can be calculated to generally well within ±5% of an electromagnetic-based database. The RTDF-derived bulk scalar optical properties result in brightness temperature errors to generally within about ±4 K at 874 GHz. Differing microphysics assumptions can easily exceed such errors. Similar findings are found for the bulk scattering phase functions. This finding is owing to the scattering solutions being dominated by the processes of diffraction and reflection, both being well described by RTDF. The impact of centimetre-sized complex ice crystals on interpreting cirrus polarisation measurements at sub-millimetre frequencies is discussed. - Highlights: • A method of physical optics is shown to apply to size parameters as low as 18 in the mm and sub-mm-wave spectral regions. • Including ray tracing with diffraction on facets and diffraction at the cross-section of

  19. [Road Extraction in Remote Sensing Images Based on Spectral and Edge Analysis].

    Science.gov (United States)

    Zhao, Wen-zhi; Luo, Li-qun; Guo, Zhou; Yue, Jun; Yu, Xue-ying; Liu, Hui; Wei, Jing

    2015-10-01

    Roads are typically man-made objects in urban areas. Road extraction from high-resolution images has important applications for urban planning and transportation development. However, due to the confusion of spectral characteristic, it is difficult to distinguish roads from other objects by merely using traditional classification methods that mainly depend on spectral information. Edge is an important feature for the identification of linear objects (e. g. , roads). The distribution patterns of edges vary greatly among different objects. It is crucial to merge edge statistical information into spectral ones. In this study, a new method that combines spectral information and edge statistical features has been proposed. First, edge detection is conducted by using self-adaptive mean-shift algorithm on the panchromatic band, which can greatly reduce pseudo-edges and noise effects. Then, edge statistical features are obtained from the edge statistical model, which measures the length and angle distribution of edges. Finally, by integrating the spectral and edge statistical features, SVM algorithm is used to classify the image and roads are ultimately extracted. A series of experiments are conducted and the results show that the overall accuracy of proposed method is 93% comparing with only 78% overall accuracy of the traditional. The results demonstrate that the proposed method is efficient and valuable for road extraction, especially on high-resolution images.

  20. Photolysis of NO2 at multiple wavelengths in the spectral region 200-205 nm - A velocity map imaging study

    NARCIS (Netherlands)

    Coroiu, A.M.; Parker, D.H.; Groenenboom, G.C.; Barr, J.; Novalbos, I.T.; Whitaker, B.J.

    2006-01-01

    A study of the photodissociation dynamics of NO2 in the 200-205 nm region using resonance enhanced multiphoton ionization (REMPI) in conjunction with the velocity map imaging technique is presented. We chose this region because it allowed the use of a single laser to photodissociate the NO2 molecule

  1. Difference between healthy children and ADHD based on wavelet spectral analysis of nuclear magnetic resonance images

    International Nuclear Information System (INIS)

    González Gómez Dulce, I.; Moreno Barbosa, E.; Hernández, Mario Iván Martínez; Méndez, José Ramos; Silvia, Hidalgo Tobón; Pilar, Dies Suarez; Eduardo, Barragán Pérez; Benito, De Celis Alonso

    2014-01-01

    The main goal of this project was to create a computer algorithm based on wavelet analysis of region of homogeneity images obtained during resting state studies. Ideally it would automatically diagnose ADHD. Because the cerebellum is an area known to be affected by ADHD, this study specifically analysed this region. Male right handed volunteers (infants with ages between 7 and 11 years old) were studied and compared with age matched controls. Statistical differences between the values of the absolute integrated wavelet spectrum were found and showed significant differences (p<0.0015) between groups. This difference might help in the future to distinguish healthy from ADHD patients and therefore diagnose ADHD. Even if results were statistically significant, the small size of the sample limits the applicability of this methods as it is presented here, and further work with larger samples and using freely available datasets must be done

  2. Difference between healthy children and ADHD based on wavelet spectral analysis of nuclear magnetic resonance images

    Energy Technology Data Exchange (ETDEWEB)

    González Gómez Dulce, I., E-mail: isabeldgg@hotmail.com, E-mail: emoreno@fcfm.buap.mx, E-mail: mim@fcfm.buap.mx, E-mail: joserm84@gmail.com; Moreno Barbosa, E., E-mail: isabeldgg@hotmail.com, E-mail: emoreno@fcfm.buap.mx, E-mail: mim@fcfm.buap.mx, E-mail: joserm84@gmail.com; Hernández, Mario Iván Martínez, E-mail: isabeldgg@hotmail.com, E-mail: emoreno@fcfm.buap.mx, E-mail: mim@fcfm.buap.mx, E-mail: joserm84@gmail.com; Méndez, José Ramos, E-mail: isabeldgg@hotmail.com, E-mail: emoreno@fcfm.buap.mx, E-mail: mim@fcfm.buap.mx, E-mail: joserm84@gmail.com [Faculty of Physics and Mathematics, BUAP, Puebla, Pue. (Mexico); Silvia, Hidalgo Tobón [Hospital Infantil de México, Federico Gómez, Mexico DF. Mexico and Physics Department, Universidad Autónoma Metropolitana. Iztapalapa, Mexico DF. (Mexico); Pilar, Dies Suarez, E-mail: pilydies@yahoo.com, E-mail: neurodoc@prodigy.net.mx; Eduardo, Barragán Pérez, E-mail: pilydies@yahoo.com, E-mail: neurodoc@prodigy.net.mx [Hospital Infantil de México, Federico Gómez, Mexico DF. (Mexico); Benito, De Celis Alonso, E-mail: benileon@yahoo.com [Faculty of Physics and Mathematics, BUAP, Puebla, Pue. Mexico and Fundación para el Desarrollo Carlos Sigüenza. Puebla, Pue (Mexico)

    2014-11-07

    The main goal of this project was to create a computer algorithm based on wavelet analysis of region of homogeneity images obtained during resting state studies. Ideally it would automatically diagnose ADHD. Because the cerebellum is an area known to be affected by ADHD, this study specifically analysed this region. Male right handed volunteers (infants with ages between 7 and 11 years old) were studied and compared with age matched controls. Statistical differences between the values of the absolute integrated wavelet spectrum were found and showed significant differences (p<0.0015) between groups. This difference might help in the future to distinguish healthy from ADHD patients and therefore diagnose ADHD. Even if results were statistically significant, the small size of the sample limits the applicability of this methods as it is presented here, and further work with larger samples and using freely available datasets must be done.

  3. Difference between healthy children and ADHD based on wavelet spectral analysis of nuclear magnetic resonance images

    Science.gov (United States)

    González Gómez, Dulce I.; Moreno Barbosa, E.; Martínez Hernández, Mario Iván; Ramos Méndez, José; Hidalgo Tobón, Silvia; Dies Suarez, Pilar; Barragán Pérez, Eduardo; De Celis Alonso, Benito

    2014-11-01

    The main goal of this project was to create a computer algorithm based on wavelet analysis of region of homogeneity images obtained during resting state studies. Ideally it would automatically diagnose ADHD. Because the cerebellum is an area known to be affected by ADHD, this study specifically analysed this region. Male right handed volunteers (infants with ages between 7 and 11 years old) were studied and compared with age matched controls. Statistical differences between the values of the absolute integrated wavelet spectrum were found and showed significant differences (pADHD patients and therefore diagnose ADHD. Even if results were statistically significant, the small size of the sample limits the applicability of this methods as it is presented here, and further work with larger samples and using freely available datasets must be done.

  4. Spike sorting using locality preserving projection with gap statistics and landmark-based spectral clustering.

    Science.gov (United States)

    Nguyen, Thanh; Khosravi, Abbas; Creighton, Douglas; Nahavandi, Saeid

    2014-12-30

    Understanding neural functions requires knowledge from analysing electrophysiological data. The process of assigning spikes of a multichannel signal into clusters, called spike sorting, is one of the important problems in such analysis. There have been various automated spike sorting techniques with both advantages and disadvantages regarding accuracy and computational costs. Therefore, developing spike sorting methods that are highly accurate and computationally inexpensive is always a challenge in the biomedical engineering practice. An automatic unsupervised spike sorting method is proposed in this paper. The method uses features extracted by the locality preserving projection (LPP) algorithm. These features afterwards serve as inputs for the landmark-based spectral clustering (LSC) method. Gap statistics (GS) is employed to evaluate the number of clusters before the LSC can be performed. The proposed LPP-LSC is highly accurate and computationally inexpensive spike sorting approach. LPP spike features are very discriminative; thereby boost the performance of clustering methods. Furthermore, the LSC method exhibits its efficiency when integrated with the cluster evaluator GS. The proposed method's accuracy is approximately 13% superior to that of the benchmark combination between wavelet transformation and superparamagnetic clustering (WT-SPC). Additionally, LPP-LSC computing time is six times less than that of the WT-SPC. LPP-LSC obviously demonstrates a win-win spike sorting solution meeting both accuracy and computational cost criteria. LPP and LSC are linear algorithms that help reduce computational burden and thus their combination can be applied into real-time spike analysis. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. Seismoelectric Effects based on Spectral-Element Method for Subsurface Fluid Characterization

    Science.gov (United States)

    Morency, C.

    2017-12-01

    Present approaches for subsurface imaging rely predominantly on seismic techniques, which alone do not capture fluid properties and related mechanisms. On the other hand, electromagnetic (EM) measurements add constraints on the fluid phase through electrical conductivity and permeability, but EM signals alone do not offer information of the solid structural properties. In the recent years, there have been many efforts to combine both seismic and EM data for exploration geophysics. The most popular approach is based on joint inversion of seismic and EM data, as decoupled phenomena, missing out the coupled nature of seismic and EM phenomena such as seismoeletric effects. Seismoelectric effects are related to pore fluid movements with respect to the solid grains. By analyzing coupled poroelastic seismic and EM signals, one can capture a pore scale behavior and access both structural and fluid properties.Here, we model the seismoelectric response by solving the governing equations derived by Pride and Garambois (1994), which correspond to Biot's poroelastic wave equations and Maxwell's electromagnetic wave equations coupled electrokinetically. We will show that these coupled wave equations can be numerically implemented by taking advantage of viscoelastic-electromagnetic mathematical equivalences. These equations will be solved using a spectral-element method (SEM). The SEM, in contrast to finite-element methods (FEM) uses high degree Lagrange polynomials. Not only does this allow the technique to handle complex geometries similarly to FEM, but it also retains exponential convergence and accuracy due to the use of high degree polynomials. Finally, we will discuss how this is a first step toward full coupled seismic-EM inversion to improve subsurface fluid characterization. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  6. Study on text mining algorithm for ultrasound examination of chronic liver diseases based on spectral clustering

    Science.gov (United States)

    Chang, Bingguo; Chen, Xiaofei

    2018-05-01

    Ultrasonography is an important examination for the diagnosis of chronic liver disease. The doctor gives the liver indicators and suggests the patient's condition according to the description of ultrasound report. With the rapid increase in the amount of data of ultrasound report, the workload of professional physician to manually distinguish ultrasound results significantly increases. In this paper, we use the spectral clustering method to cluster analysis of the description of the ultrasound report, and automatically generate the ultrasonic diagnostic diagnosis by machine learning. 110 groups ultrasound examination report of chronic liver disease were selected as test samples in this experiment, and the results were validated by spectral clustering and compared with k-means clustering algorithm. The results show that the accuracy of spectral clustering is 92.73%, which is higher than that of k-means clustering algorithm, which provides a powerful ultrasound-assisted diagnosis for patients with chronic liver disease.

  7. Liquid crystal-based Mueller matrix spectral imaging polarimetry for parameterizing mineral structural organization.

    Science.gov (United States)

    Gladish, James C; Duncan, Donald D

    2017-01-20

    Herein, we discuss the remote assessment of the subwavelength organizational structure of a medium. Specifically, we use spectral imaging polarimetry, as the vector nature of polarized light enables it to interact with optical anisotropies within a medium, while the spectral aspect of polarization is sensitive to small-scale structure. The ability to image these effects allows for inference of spatial structural organization parameters. This work describes a methodology for revealing structural organization by exploiting the Stokes/Mueller formalism and by utilizing measurements from a spectral imaging polarimeter constructed from liquid crystal variable retarders and a liquid crystal tunable filter. We provide results to validate the system and then show results from measurements on a mineral sample.

  8. Hyper-spectral modulation fluorescent imaging using double acousto-optical tunable filter based on TeO2-crystals

    International Nuclear Information System (INIS)

    Zaytsev, Kirill I; Perchik, Alexey V; Chernomyrdin, Nikita V; Yurchenko, Stanislav O; Kudrin, Konstantin G; Reshetov, Igor V

    2015-01-01

    We have proposed a method for hyper-spectral fluorescent imaging based on acousto-optical filtering. The object of interest was pumped using ultraviolet radiation of mercury lamp equipped with monochromatic excitation filter with the window of transparency centered at 365 nm. Double TeO 2 -based acousto-optical filter, tunable in range from 430 to 780 nm and having 2 nm bandwidth of spectral transparency, was used in order to detect quasimonochromatic images of object fluorescence. Modulating of ultraviolet pump intensity was used in order to reduce an impact of non-fluorescent background on the sample fluorescent imaging. The technique for signal-to-noise ratio improvement, based on fluorescence intensity estimation via digital processing of modulated video sequence of fluorescent object, was introduced. We have implemented the proposed technique for the test sample studying and we have discussed its possible applications

  9. Spectral properties of the narrow-line region in Seyfert galaxies selected from the SDSS-DR7

    Science.gov (United States)

    Vaona, L.; Ciroi, S.; Di Mille, F.; Cracco, V.; La Mura, G.; Rafanelli, P.

    2012-12-01

    Although the properties of the narrow-line region (NLR) of active galactic nuclei (AGN) have been deeply studied by many authors in the past three decades, many questions are still open. The main goal of this work is to explore the NLR of Seyfert galaxies by collecting a large statistical spectroscopic sample of Seyfert 2 and Intermediate-type Seyfert galaxies having a high signal-to-noise ratio in order to take advantage of a high number of emission lines to be accurately measured. 2153 Seyfert 2 and 521 Intermediate-type Seyfert spectra were selected from Sloan Digital Sky Survey Data Release 7 (SDSS-DR7) with a diagnostic diagram based on the oxygen emission-line ratios. All the emission lines, broad components included, were measured by means of a self-developed code, after the subtraction of the stellar component. Physical parameters, such as internal reddening, ionization parameter, temperature, density, gas and stellar velocity dispersion were determined for each object. Furthermore, we estimated mass and radius of the NLR, kinetic energy of the ionized gas and black hole accretion rate. From the emission-line analysis and the estimated physical properties, it appears that the NLR is similar in Seyfert 2 and Intermediate-Seyfert galaxies. The only differences, lower extinction, gas kinematics in general not dominated by the host galaxy gravitational potential and higher percentage of [O III]λ5007 blue asymmetries in Intermediate-Seyfert, can be ascribed to an effect of inclination of our line of sight with respect to the torus axis.

  10. Investigation on water content in fresco mock-ups in the microwave and near-IR spectral regions

    International Nuclear Information System (INIS)

    Magrini, Donata; Riminesi, Cristiano; Cucci, Costanza; Olmi, Roberto; Picollo, Marcello

    2017-01-01

    Water diffusion inside masonry is responsible for the majority of the decay phenomena observed in wall paintings and frescos. Thus, the diagnostics of moisture and water content and their monitoring represent a key issue. In order to preserve the integrity of surfaces of artistic interest, investigations by means of non-destructive techniques (NDT) are preferred over others. The aim of this research is to determine methodologies to quantify the moisture content (MC) of frescos by means of the integrated use of two non-invasive techniques, namely fiber optic reflectance spectroscopy (FORS) in the near-IR region and evanescent field dielectrometry (EFD) in the microwave range. The FORS technique has been employed in order to assess the amount of water adsorbed from the surface by means of an analysis of the reflectance spectra in the Vis–NIR (350-2200 nm) range. This technique investigates the electronic and vibrational transitions that are characteristic of each compound and enables their identification. The water content is evaluated on the basis of the 1920 nm and 1450 nm absorption bands. The EFD system consists of a resonant probe connected to a network analyzer. The resonance frequency of the cavity under different moisture-content conditions of frescos is in the 1.0–1.5 GHz range. The device makes it possible to compute, in real time, the MC from a measurement of the transmission coefficient (amplitude versus frequency) through the probe. Fresco mock-ups have been prepared in collaboration with the Opificio delle Pietre Dure in order to recreate most of the possible chromatic shades obtained by mixing iron oxides and hydroxide-based pigments. Measurements were performed by employing both techniques on fresco models after wet-dry cycles obtained by means of poultices with a known water content. The results obtained with these two techniques were compared, and cross relationships between the EFD and FORS data were defined. (paper)

  11. Land degradation mapping based on hyperion data in desertification region of northwest China

    Science.gov (United States)

    Cheng, Penggen; Wu, Jian; Ouyang, Ping; He, Ting

    2008-10-01

    Desertification is an alarming sign of land degradation in Henshan county of northwest china. Due to the considerable costs of detailed ground surveys of this phenomenon, remote sensing is an appropriate alternative for analyzing and evaluating the risks of the expansion of land degradation. Degradation features can be detected directly or indirectly by using image data. In this paper, based on the Hyperion images of Hengshan desertification region of northwest china, a new algorithm aimed at land degradation mapping, called Land Degradation Index (LDI), was put forward. This new algorithm is based on the classified process. We applied the linear spectral unmixing algorithm with the training samples derived from the formerly classified process so as to find out new endmembers in the RMS error imagine. After that, using neutral net mapping with new training samples, the classified result was gained. In addition, after applying mask processing, the soils were grouped to 3 types (Kappa =0.90): highly degraded soils, moderately degraded soils and slightly degraded soils. By analyzing 3 mapping methods: mixture-classification, the spectral angle mapper and mixturetuned matched filtering, the results suggest that the mixture-classification has the higher accuracy (Kappa=0.7075) than the spectral angle mapper (Kappa=0.5418) and the mixture-tuned matched filter (Kappa=0.6039). As a result, the mixture-classification is selected to carry out Land Degradation Index analysis.

  12. Film thickness measurement based on nonlinear phase analysis using a Linnik microscopic white-light spectral interferometer.

    Science.gov (United States)

    Guo, Tong; Chen, Zhuo; Li, Minghui; Wu, Juhong; Fu, Xing; Hu, Xiaotang

    2018-04-20

    Based on white-light spectral interferometry and the Linnik microscopic interference configuration, the nonlinear phase components of the spectral interferometric signal were analyzed for film thickness measurement. The spectral interferometric signal was obtained using a Linnik microscopic white-light spectral interferometer, which includes the nonlinear phase components associated with the effective thickness, the nonlinear phase error caused by the double-objective lens, and the nonlinear phase of the thin film itself. To determine the influence of the effective thickness, a wavelength-correction method was proposed that converts the effective thickness into a constant value; the nonlinear phase caused by the effective thickness can then be determined and subtracted from the total nonlinear phase. A method for the extraction of the nonlinear phase error caused by the double-objective lens was also proposed. Accurate thickness measurement of a thin film can be achieved by fitting the nonlinear phase of the thin film after removal of the nonlinear phase caused by the effective thickness and by the nonlinear phase error caused by the double-objective lens. The experimental results demonstrated that both the wavelength-correction method and the extraction method for the nonlinear phase error caused by the double-objective lens improve the accuracy of film thickness measurements.

  13. Bidirectional-Convolutional LSTM Based Spectral-Spatial Feature Learning for Hyperspectral Image Classification

    Directory of Open Access Journals (Sweden)

    Qingshan Liu

    2017-12-01

    Full Text Available This paper proposes a novel deep learning framework named bidirectional-convolutional long short term memory (Bi-CLSTM network to automatically learn the spectral-spatial features from hyperspectral images (HSIs. In the network, the issue of spectral feature extraction is considered as a sequence learning problem, and a recurrent connection operator across the spectral domain is used to address it. Meanwhile, inspired from the widely used convolutional neural network (CNN, a convolution operator across the spatial domain is incorporated into the network to extract the spatial feature. In addition, to sufficiently capture the spectral information, a bidirectional recurrent connection is proposed. In the classification phase, the learned features are concatenated into a vector and fed to a Softmax classifier via a fully-connected operator. To validate the effectiveness of the proposed Bi-CLSTM framework, we compare it with six state-of-the-art methods, including the popular 3D-CNN model, on three widely used HSIs (i.e., Indian Pines, Pavia University, and Kennedy Space Center. The obtained results show that Bi-CLSTM can improve the classification performance by almost 1.5 % as compared to 3D-CNN.

  14. Full waveform inversion based on the optimized gradient and its spectral implementation

    KAUST Repository

    Wu, Zedong; Alkhalifah, Tariq Ali

    2014-01-01

    for the convergence are available, the high number of iterations required to approach a solution renders FWI as very expensive (especially in 3D). A spectral implementation in which the wavefields are extrapolated and gradients are calculated in the wavenumber domain

  15. Conformational determination of [Leu]enkephalin based on theoretical and experimental VA and VCD spectral analyses

    DEFF Research Database (Denmark)

    Abdali, Salim; Jalkanen, Karl J.; Cao, X.

    2004-01-01

    Conformational determination of [Leu]enkephalin in DMSO-d6 is carried out using VA and VCD spectral analyses. Conformational energies, vibrational frequencies and VA and VCD intensities are calculated using DFT at B3LYP/6-31G* level of theory. Comparison between the measured spectra...

  16. A Spectral Geometrical Model for Compton Scatter Tomography Based on the SSS Approximation

    DEFF Research Database (Denmark)

    Kazantsev, Ivan G.; Olsen, Ulrik Lund; Poulsen, Henning Friis

    2016-01-01

    The forward model of single scatter in the Positron Emission Tomography for a detector system possessing an excellent spectral resolution under idealized geometrical assumptions is investigated. This model has the form of integral equations describing a flux of photons emanating from the same ann...

  17. Spectral trees as a robust annotation tool in LC–MS based metabolomics

    NARCIS (Netherlands)

    Hooft, van der J.J.J.; Vervoort, J.J.M.; Bino, R.J.; Vos, de C.H.

    2012-01-01

    The identification of large series of metabolites detectable by mass spectrometry (MS) in crude extracts is a challenging task. In order to test and apply the so-called multistage mass spectrometry (MS n ) spectral tree approach as tool in metabolite identification in complex sample extracts, we

  18. Demonstration of a diode-laser-based high spectral resolution lidar (HSRL) for quantitative profiling of clouds and aerosols.

    Science.gov (United States)

    Hayman, Matthew; Spuler, Scott

    2017-11-27

    We present a demonstration of a diode-laser-based high spectral resolution lidar. It is capable of performing calibrated retrievals of aerosol and cloud optical properties at a 150 m range resolution with less than 1 minute integration time over an approximate range of 12 km during day and night. This instrument operates at 780 nm, a wavelength that is well established for reliable semiconductor lasers and detectors, and was chosen because it corresponds to the D2 rubidium absorption line. A heated vapor reference cell of isotopic rubidium 87 is used as an effective and reliable aerosol signal blocking filter in the instrument. In principle, the diode-laser-based high spectral resolution lidar can be made cost competitive with elastic backscatter lidar systems, yet delivers a significant improvement in data quality through direct retrieval of quantitative optical properties of clouds and aerosols.

  19. Dual-drive Mach-Zehnder modulator-based reconfigurable and transparent spectral conversion for dense wavelength division multiplexing transmissions

    Science.gov (United States)

    Mao, Mingzhi; Qian, Chen; Cao, Bingyao; Zhang, Qianwu; Song, Yingxiong; Wang, Min

    2017-09-01

    A digital signal process enabled dual-drive Mach-Zehnder modulator (DD-MZM)-based spectral converter is proposed and extensively investigated to realize dynamically reconfigurable and high transparent spectral conversion. As another important innovation point of the paper, to optimize the converter performance, the optimum operation conditions of the proposed converter are deduced, statistically simulated, and experimentally verified. The optimum conditions supported-converter performances are verified by detail numerical simulations and experiments in intensity-modulation and direct-detection-based network in terms of frequency detuning range-dependent conversion efficiency, strict operation transparency for user signal characteristics, impact of parasitic components on the conversion performance, as well as the converted component waveform are almost nondistortion. It is also found that the converter has the high robustness to the input signal power, optical signal-to-noise ratio variations, extinction ratio, and driving signal frequency.

  20. Pepper seed variety identification based on visible/near-infrared spectral technology

    Science.gov (United States)

    Li, Cuiling; Wang, Xiu; Meng, Zhijun; Fan, Pengfei; Cai, Jichen

    2016-11-01

    Pepper is a kind of important fruit vegetable, with the expansion of pepper hybrid planting area, detection of pepper seed purity is especially important. This research used visible/near infrared (VIS/NIR) spectral technology to detect the variety of single pepper seed, and chose hybrid pepper seeds "Zhuo Jiao NO.3", "Zhuo Jiao NO.4" and "Zhuo Jiao NO.5" as research sample. VIS/NIR spectral data of 80 "Zhuo Jiao NO.3", 80 "Zhuo Jiao NO.4" and 80 "Zhuo Jiao NO.5" pepper seeds were collected, and the original spectral data was pretreated with standard normal variable (SNV) transform, first derivative (FD), and Savitzky-Golay (SG) convolution smoothing methods. Principal component analysis (PCA) method was adopted to reduce the dimension of the spectral data and extract principal components, according to the distribution of the first principal component (PC1) along with the second principal component(PC2) in the twodimensional plane, similarly, the distribution of PC1 coupled with the third principal component(PC3), and the distribution of PC2 combined with PC3, distribution areas of three varieties of pepper seeds were divided in each twodimensional plane, and the discriminant accuracy of PCA was tested through observing the distribution area of samples' principal components in validation set. This study combined PCA and linear discriminant analysis (LDA) to identify single pepper seed varieties, results showed that with the FD preprocessing method, the discriminant accuracy of pepper seed varieties was 98% for validation set, it concludes that using VIS/NIR spectral technology is feasible for identification of single pepper seed varieties.

  1. Adaptive Spectral Doppler Estimation

    DEFF Research Database (Denmark)

    Gran, Fredrik; Jakobsson, Andreas; Jensen, Jørgen Arendt

    2009-01-01

    . The methods can also provide better quality of the estimated power spectral density (PSD) of the blood signal. Adaptive spectral estimation techniques are known to pro- vide good spectral resolution and contrast even when the ob- servation window is very short. The 2 adaptive techniques are tested......In this paper, 2 adaptive spectral estimation techniques are analyzed for spectral Doppler ultrasound. The purpose is to minimize the observation window needed to estimate the spectrogram to provide a better temporal resolution and gain more flexibility when designing the data acquisition sequence...... and compared with the averaged periodogram (Welch’s method). The blood power spectral capon (BPC) method is based on a standard minimum variance technique adapted to account for both averaging over slow-time and depth. The blood amplitude and phase estimation technique (BAPES) is based on finding a set...

  2. Strengthening regional innovation through network-based innovation brokering

    OpenAIRE

    Svare, Helge; Gausdal, Anne Haugen

    2015-01-01

    The primary objective of this paper is to demonstrate how regional innovation system theory may be translated into manageable micro-level methods with the potential for strengthening the productive dynamics of a regional innovation system. The paper meets this objective by presenting network-based innovation brokering (NBIB), a practical method designed using insights from regional innovation system theory and trust theory. Five cases from two Norwegian regional innovation networks show that ...

  3. Automated classification and visualization of healthy and pathological dental tissues based on near-infrared hyper-spectral imaging

    Science.gov (United States)

    Usenik, Peter; Bürmen, Miran; Vrtovec, Tomaž; Fidler, Aleš; Pernuš, Franjo; Likar, Boštjan

    2011-03-01

    Despite major improvements in dental healthcare and technology, dental caries remains one of the most prevalent chronic diseases of modern society. The initial stages of dental caries are characterized by demineralization of enamel crystals, commonly known as white spots which are difficult to diagnose. If detected early enough, such demineralization can be arrested and reversed by non-surgical means through well established dental treatments (fluoride therapy, anti-bacterial therapy, low intensity laser irradiation). Near-infrared (NIR) hyper-spectral imaging is a new promising technique for early detection of demineralization based on distinct spectral features of healthy and pathological dental tissues. In this study, we apply NIR hyper-spectral imaging to classify and visualize healthy and pathological dental tissues including enamel, dentin, calculus, dentin caries, enamel caries and demineralized areas. For this purpose, a standardized teeth database was constructed consisting of 12 extracted human teeth with different degrees of natural dental lesions imaged by NIR hyper-spectral system, X-ray and digital color camera. The color and X-ray images of teeth were presented to a clinical expert for localization and classification of the dental tissues, thereby obtaining the gold standard. Principal component analysis was used for multivariate local modeling of healthy and pathological dental tissues. Finally, the dental tissues were classified by employing multiple discriminant analysis. High agreement was observed between the resulting classification and the gold standard with the classification sensitivity and specificity exceeding 85 % and 97 %, respectively. This study demonstrates that NIR hyper-spectral imaging has considerable diagnostic potential for imaging hard dental tissues.

  4. Application of spectral decomposition of LIDAR-based headwind profiles in windshear detection at the Hong Kong International Airport

    Directory of Open Access Journals (Sweden)

    Tsz-Chun Wu

    2018-01-01

    Full Text Available In aviation, rapidly fluctuating headwind/tailwind may lead to high horizontal windshear, posing potential safety hazards to aircraft. So far, windshear alerts are issued by considering directly the headwind differences measured along the aircraft flight path (e.g. based on Doppler velocities from remote-sensing. In this paper, we propose and demonstrate a new methodology for windshear alerting with the technique of spectral decomposition. Through Fourier transformation of the LIDAR-based headwind profiles in 2012 and 2014 at arrival corridors 07LA and 25RA of the Hong Kong International Airport (HKIA, we study the occurrence of windshear in the spectral domain. Using a threshold-based approach, we investigate performance of single and multiple channel detection algorithms and validate the results against pilot reports. With the receiver operating characteristic (ROC diagram, we successfully demonstrate feasibility of this approach to alert windshear by showing a comparable performance of the triple channel detection algorithm and a consistent hit rate gain (07LA in particular of 4.5 to 8 % in quadruple channel detection against GLYGA, which is the currently operational algorithm in HKIA. We also observe that some length scales are particularly sensitive to windshear events which may be closely related to the local geography of HKIA. This study serves to open a new door for the methodology of windshear detection in the spectral domain for the aviation community.

  5. The Effect of Epidermal Structures on Leaf Spectral Signatures of Ice Plants (Aizoaceae

    Directory of Open Access Journals (Sweden)

    René Hans-Jürgen Heim

    2015-12-01

    Full Text Available Epidermal structures (ES of leaves are known to affect the functional properties and spectral responses. Spectral studies focused mostly on the effect of hairs or wax layers only. We studied a wider range of different ES and their impact on spectral properties. Additionally, we identified spectral regions that allow distinguishing different ES. We used a field spectrometer to measure ex situ leaf spectral responses from 350 nm–2500 nm. A spectral library for 25 species of the succulent family Aizoaceae was assembled. Five functional types were defined based on ES: flat epidermal cell surface, convex to papillary epidermal cell surface, bladder cells, hairs and wax cover. We tested the separability of ES using partial least squares discriminant analysis (PLS-DA based on the spectral data. Subsequently, variable importance (VIP was calculated to identify spectral regions relevant for discriminating our functional types (classes. Classification performance was high, with a kappa value of 0.9 indicating well-separable spectral classes. VIP calculations identified six spectral regions of increased importance for the classification. We confirmed and extended previous findings regarding the visible-near-infrared spectral region. Our experiments also confirmed that epidermal leaf traits can be classified due to clearly distinguishable spectral signatures across species and genera within the Aizoaceae.

  6. Distribution of hydrothermally altered rocks in the Reko Diq, Pakistan mineralized area based on spectral analysis of ASTER data

    Science.gov (United States)

    Rowan, L.C.; Schmidt, R.G.; Mars, J.C.

    2006-01-01

    The Reko Diq, Pakistan mineralized study area, approximately 10??km in diameter, is underlain by a central zone of hydrothermally altered rocks associated with Cu-Au mineralization. The surrounding country rocks are a variable mixture of unaltered volcanic rocks, fluvial deposits, and eolian quartz sand. Analysis of 15-band Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data of the study area, aided by laboratory spectral reflectance and spectral emittance measurements of field samples, shows that phyllically altered rocks are laterally extensive, and contain localized areas of argillically altered rocks. In the visible through shortwave-infrared (VNIR + SWIR) phyllically altered rocks are characterized by Al-OH absorption in ASTER band 6 because of molecular vibrations in muscovite, whereas argillically altered rocks have an absorption feature in band 5 resulting from alunite. Propylitically altered rocks form a peripheral zone and are present in scattered exposures within the main altered area. Chlorite and muscovite cause distinctive absorption features at 2.33 and 2.20????m, respectively, although less intense 2.33????m absorption is also present in image spectra of country rocks. Important complementary lithologic information was derived by analysis of the spectral emittance data in the 5 thermal-infrared (TIR) bands. Silicified rocks were not distinguished in the 9 VNIR + SWIR bands because of the lack of diagnostic spectral absorption features in quartz in this wavelength region. Quartz-bearing surficial deposits, as well as hydrothermally silicified rocks, were mapped in the TIR bands by using a band 13/band 12 ratio image, which is sensitive to the intensity of the quartz reststrahlen feature. Improved distinction between the quartzose surficial deposits and silicified bedrock was achieved by using matched-filter processing with TIR image spectra for reference. ?? 2006 Elsevier Inc. All rights reserved.

  7. Generation of pulsed light in the visible spectral region based on non-linear cavity dumping

    DEFF Research Database (Denmark)

    Johansson, Sandra; Andersen, Martin; Tidemand-Lichtenberg, Peter

    of 215 kHz. Both lasers were pumped with 808 nm laser diodes delivering 4 W of output power. The circulating power of the 1342 nm laser was 57 W and the peak power of the 1064 nm laser reaching the PPKTP crystal was 17 W. A peak power of approximately 4 W at 593 nm was measured. Accounting...

  8. Spectral light separator based on deep-subwavelength resonant apertures in a metallic film

    Energy Technology Data Exchange (ETDEWEB)

    Büyükalp, Yasin; Catrysse, Peter B., E-mail: pcatryss@stanford.edu; Shin, Wonseok; Fan, Shanhui, E-mail: shanhui@stanford.edu [E. L. Ginzton Laboratory and Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States)

    2014-07-07

    We propose to funnel, select, and collect light spectrally by exploiting the unique properties of deep-subwavelength resonant apertures in a metallic film. In our approach, each aperture has an electromagnetic cross section that is much larger than its physical size while the frequency of the collected light is controlled by its height through the Fabry-Pérot resonance mechanism. The electromagnetic crosstalk between apertures remains low despite physical separations in the deep-subwavelength range. The resulting device enables an extremely efficient, subwavelength way to decompose light into its spectral components without the loss of photons and spatial coregistration errors. As a specific example, we show a subwavelength-size structure with three deep-subwavelength slits in a metallic film designed to operate in the mid-wave infrared range between 3 and 5.5 μm.

  9. SPECTRAL COLOR INDICES BASED GEOSPATIAL MODELING OF SOIL ORGANIC MATTER IN CHITWAN DISTRICT, NEPAL

    Directory of Open Access Journals (Sweden)

    U. K. Mandal

    2016-06-01

    Full Text Available Space Technology provides a resourceful-cost effective means to assess soil nutrients essential for soil management plan. Soil organic matter (SOM is one of valuable controlling productivity of crops by providing nutrient in farming systems. Geospatial modeling of soil organic matter is essential if there is unavailability of soil test laboratories and its strong spatial correlation. In the present analysis, soil organic matter is modeled from satellite image derived spectral color indices. Brightness Index (BI, Coloration Index (CI, Hue Index (HI, Redness Index (RI and Saturation Index (SI were calculated by converting DN value to radiance and radiance to reflectance from Thematic Mapper image. Geospatial model was developed by regressing SOM with color indices and producing multiple regression model using stepwise regression technique. The multiple regression equation between SOM and spectral indices was significant with R = 0. 56 at 95% confidence level. The resulting MLR equation was then used for the spatial prediction for the entire study area. Redness Index was found higher significance in estimating the SOM. It was used to predict SOM as auxiliary variables using cokringing spatial interpolation technique. It was tested in seven VDCs of Chitwan district of Nepal using Thematic Mapper remotely sensed data. SOM was found to be measured ranging from 0.15% to 4.75 %, with a mean of 2.24 %. Remotely sensed data derived spectral color indices have the potential as useful auxiliary variables for estimating SOM content to generate soil fertility management plans.

  10. Prediction of meat spectral patterns based on optical properties and concentrations of the major constituents.

    Science.gov (United States)

    ElMasry, Gamal; Nakauchi, Shigeki

    2016-03-01

    A simulation method for approximating spectral signatures of minced meat samples was developed depending on concentrations and optical properties of the major chemical constituents. Minced beef samples of different compositions scanned on a near-infrared spectroscopy and on a hyperspectral imaging system were examined. Chemical composition determined heuristically and optical properties collected from authenticated references were simulated to approximate samples' spectral signatures. In short-wave infrared range, the resulting spectrum equals the sum of the absorption of three individual absorbers, that is, water, protein, and fat. By assuming homogeneous distributions of the main chromophores in the mince samples, the obtained absorption spectra are found to be a linear combination of the absorption spectra of the major chromophores present in the sample. Results revealed that developed models were good enough to derive spectral signatures of minced meat samples with a reasonable level of robustness of a high agreement index value more than 0.90 and ratio of performance to deviation more than 1.4.

  11. Wavelength selection for portable noninvasive blood component measurement system based on spectral difference coefficient and dynamic spectrum

    Science.gov (United States)

    Feng, Ximeng; Li, Gang; Yu, Haixia; Wang, Shaohui; Yi, Xiaoqing; Lin, Ling

    2018-03-01

    Noninvasive blood component analysis by spectroscopy has been a hotspot in biomedical engineering in recent years. Dynamic spectrum provides an excellent idea for noninvasive blood component measurement, but studies have been limited to the application of broadband light sources and high-resolution spectroscopy instruments. In order to remove redundant information, a more effective wavelength selection method has been presented in this paper. In contrast to many common wavelength selection methods, this method is based on sensing mechanism which has a clear mechanism and can effectively avoid the noise from acquisition system. The spectral difference coefficient was theoretically proved to have a guiding significance for wavelength selection. After theoretical analysis, the multi-band spectral difference coefficient-wavelength selection method combining with the dynamic spectrum was proposed. An experimental analysis based on clinical trial data from 200 volunteers has been conducted to illustrate the effectiveness of this method. The extreme learning machine was used to develop the calibration models between the dynamic spectrum data and hemoglobin concentration. The experiment result shows that the prediction precision of hemoglobin concentration using multi-band spectral difference coefficient-wavelength selection method is higher compared with other methods.

  12. Three-Dimensional Reconstruction from Single Image Base on Combination of CNN and Multi-Spectral Photometric Stereo

    Directory of Open Access Journals (Sweden)

    Liang Lu

    2018-03-01

    Full Text Available Multi-spectral photometric stereo can recover pixel-wise surface normal from a single RGB image. The difficulty lies in that the intensity in each channel is the tangle of illumination, albedo and camera response; thus, an initial estimate of the normal is required in optimization-based solutions. In this paper, we propose to make a rough depth estimation using the deep convolutional neural network (CNN instead of using depth sensors or binocular stereo devices. Since high-resolution ground-truth data is expensive to obtain, we designed a network and trained it with rendered images of synthetic 3D objects. We use the model to predict initial normal of real-world objects and iteratively optimize the fine-scale geometry in the multi-spectral photometric stereo framework. The experimental results illustrate the improvement of the proposed method compared with existing methods.

  13. Three-Dimensional Reconstruction from Single Image Base on Combination of CNN and Multi-Spectral Photometric Stereo

    Science.gov (United States)

    Lu, Liang; Qi, Lin; Luo, Yisong; Jiao, Hengchao; Dong, Junyu

    2018-01-01

    Multi-spectral photometric stereo can recover pixel-wise surface normal from a single RGB image. The difficulty lies in that the intensity in each channel is the tangle of illumination, albedo and camera response; thus, an initial estimate of the normal is required in optimization-based solutions. In this paper, we propose to make a rough depth estimation using the deep convolutional neural network (CNN) instead of using depth sensors or binocular stereo devices. Since high-resolution ground-truth data is expensive to obtain, we designed a network and trained it with rendered images of synthetic 3D objects. We use the model to predict initial normal of real-world objects and iteratively optimize the fine-scale geometry in the multi-spectral photometric stereo framework. The experimental results illustrate the improvement of the proposed method compared with existing methods. PMID:29498703

  14. Effect of H{sup +} implantation on the optical properties of semi-insulating GaAs crystals in the IR spectral region

    Energy Technology Data Exchange (ETDEWEB)

    Klyui, N. I.; Lozinskii, V. B., E-mail: lvb@isp.kiev.ua [Jilin University, College of Physics (China); Liptuga, A. I.; Dikusha, V. N. [National Academy of Sciences of Ukraine, Lashkaryov Institute of Semiconductor Physics (Ukraine); Oksanych, A. P.; Kogdas’, M. G.; Perekhrest, A. L.; Pritchin, S. E. [Kremenchug National University (Ukraine)

    2017-03-15

    The optical properties of semi-insulating GaAs crystals subjected to multienergy hydrogen-ion implantation and treatment in a high-frequency electromagnetic field are studied in the infrared spectral region. It is established that such combined treatment provides a means for substantially increasing the transmittance of GaAs crystals to values characteristic of crystals of high optical quality. On the basis of analysis of the infrared transmittance and reflectance data, Raman spectroscopy data, and atomic-force microscopy data on the surface morphology of the crystals, a physical model is proposed to interpret the effects experimentally observed in the crystals. The model takes into account the interaction of radiation defects with the initial structural defects in the crystals as well as the effect of compensation of defect centers by hydrogen during high-frequency treatment.

  15. Second byurakan spectral sky survey. IV. Results for region centered on /chi/ = 12 /sup h/ 22 /sup m/, δ = +55 /sup o/ 00

    International Nuclear Information System (INIS)

    Makaryan, B.E.; Erastova, L.K.; Stepanyan, D.A.

    1986-01-01

    The fourth list of objects of the second Byurkan spectral sky survey in the 4 0 x 4 0 region centered on alpha= 12 /sup h/ 22 /sup m/, delta = +55 0 00' is presented. The observations were made with the 40''-52'' Schmidt telescope of the Byurkan Observatory with a set of three objective prisms. The list contains data on 106 objects and galxies and 12 blue stars. The distribution of the objects with respect to types is as follows: 16 candidates for QSO, 29 for BSO, 32 galaxies with appreciable ultraviolet continuum, among which weak Seyfert features are suspected for three, and 29 emission galaxies without appreciable ultraviolet continuum. The surface density of QSO and Seyferts down to 19 /sup m/ is more than one per square degree

  16. Effect of H+ implantation on the optical properties of semi-insulating GaAs crystals in the IR spectral region

    International Nuclear Information System (INIS)

    Klyui, N. I.; Lozinskii, V. B.; Liptuga, A. I.; Dikusha, V. N.; Oksanych, A. P.; Kogdas’, M. G.; Perekhrest, A. L.; Pritchin, S. E.

    2017-01-01

    The optical properties of semi-insulating GaAs crystals subjected to multienergy hydrogen-ion implantation and treatment in a high-frequency electromagnetic field are studied in the infrared spectral region. It is established that such combined treatment provides a means for substantially increasing the transmittance of GaAs crystals to values characteristic of crystals of high optical quality. On the basis of analysis of the infrared transmittance and reflectance data, Raman spectroscopy data, and atomic-force microscopy data on the surface morphology of the crystals, a physical model is proposed to interpret the effects experimentally observed in the crystals. The model takes into account the interaction of radiation defects with the initial structural defects in the crystals as well as the effect of compensation of defect centers by hydrogen during high-frequency treatment.

  17. Spectral gamuts and spectral gamut mapping

    Science.gov (United States)

    Rosen, Mitchell R.; Derhak, Maxim W.

    2006-01-01

    All imaging devices have two gamuts: the stimulus gamut and the response gamut. The response gamut of a print engine is typically described in CIE colorimetry units, a system derived to quantify human color response. More fundamental than colorimetric gamuts are spectral gamuts, based on radiance, reflectance or transmittance units. Spectral gamuts depend on the physics of light or on how materials interact with light and do not involve the human's photoreceptor integration or brain processing. Methods for visualizing a spectral gamut raise challenges as do considerations of how to utilize such a data-set for producing superior color reproductions. Recent work has described a transformation of spectra reduced to 6-dimensions called LabPQR. LabPQR was designed as a hybrid space with three explicit colorimetric axes and three additional spectral reconstruction axes. In this paper spectral gamuts are discussed making use of LabPQR. Also, spectral gamut mapping is considered in light of the colorimetric-spectral duality of the LabPQR space.

  18. A TALE OF TWO NARROW-LINE REGIONS: IONIZATION, KINEMATICS, AND SPECTRAL ENERGY DISTRIBUTIONS FOR A LOCAL PAIR OF MERGING OBSCURED ACTIVE GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Hainline, Kevin N.; Hickox, Ryan C.; Chen, Chien-Ting; Carroll, Christopher M.; Jones, Mackenzie L.; Zervos, Alexandros S. [Department of Physics and Astronomy, Dartmouth College, Hanover, NH 03755 (United States); Goulding, Andrew D. [Department Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States)

    2016-05-20

    We explore the gas ionization and kinematics, as well as the optical-IR spectral energy distributions for UGC 11185, a nearby pair of merging galaxies hosting obscured active galactic nuclei (AGNs), also known as SDSS J181611.72+423941.6 and J181609.37+423923.0 (J1816NE and J1816SW, z ≈ 0.04). Due to the wide separation between these interacting galaxies (∼23 kpc), observations of these objects provide a rare glimpse of the concurrent growth of supermassive black holes at an early merger stage. We use BPT line diagnostics to show that the full extent of the narrow-line emission in both galaxies is photoionized by an AGN, and confirm the existence of a 10 kpc-scale ionization cone in J1816NE, while in J1816SW the AGN narrow-line region is much more compact (1–2 kpc) and relatively undisturbed. Our observations also reveal the presence of ionized gas that nearly spans the entire distance between the galaxies, which is likely in a merger-induced tidal stream. In addition, we carry out a spectral analysis of the X-ray emission using data from XMM-Newton . These galaxies represent a useful pair to explore how the [O iii] luminosity of an AGN is dependent on the size of the region used to explore the extended emission. Given the growing evidence for AGN “flickering” over short timescales, we speculate that the appearances and impacts of these AGNs may change multiple times over the course of the galaxy merger, which is especially important given that these objects are likely the progenitors of the types of systems commonly classified as “dual AGNs.”.

  19. Thermal structure of Sikhote Alin and adjacent areas based on spectral analysis of the anomalous magnetic field

    Science.gov (United States)

    Didenko, A. N.; Nosyrev, M. Yu.; Shevchenko, B. F.; Gilmanova, G. Z.

    2017-11-01

    The depth of the base of the magnetoactive layer and the geothermal gradient in the Sikhote Alin crust are estimated based on a method determining the Curie depth point of magnetoactive masses by using spectral analysis of the anomalous magnetic field. A detailed map of the geothermal gradient is constructed for the first time for the Sikhote Alin and adjacent areas of the Central Asian belt. Analysis of this map shows that the zones with a higher geothermal gradient geographically fit the areas with a higher level of seismicity.

  20. SPECTRAL CHARACTERISTICS OF MID-INFRARED LIGHT-EMITTING DIODES BASED ON InAs (Sb,P

    Directory of Open Access Journals (Sweden)

    N. K. Zhumashev

    2016-01-01

    Full Text Available Subject of Study. We consider spectral characteristics of mid-infrared light-emitting diodes with heterostructures based on InAs(Sb,P emitting at T=300 K in the wavelength range 3.4–4.1 micrometers. The aim of the study was to search for the ways of increasing the diode efficiency. Methods. The heterostructures were grown from metal-organic chemical compounds with the use of vapor-phase epitaxial technique. The spectra were recorded under pulse excitation with the use of computer-controlled installation employing MDR-23 grating monochromator and a lock-in amplifier. InSb photodiode was used as a detector. Comparative study of electroluminescence spectra of the diodes was carried out at the temperatures equal to 300 K and 77 K. We compared the obtained data with the calculation results of the band diagrams of the heterostructures. Main Results. As a result of comparative study of the electroluminescence spectra of the diodes recorded at 300 K and 77 K we have established that increasing of their efficiency is hindered by substantial influence of Auger recombination. For the first time at 77 К we have observed the effect of stimulated emission from InAsSb active layer in light-emitting structures made of InAs/InAsSb/InAsSbP. For heterostructures with quantum wells InAs/(InAs/InAsSb/InAsSbP we have found out that at 77 К the carrier recombination occurs outside quantum wells, which points out to the insufficient carrier localization in the active layer. Thus, we have shown that the efficiency of mid-infrared light-emitting diodes based on InAs(Sb,P can be increased via suppression of Auger-recombination and improvement of carrier localization in the active region. Practical Relevance. The results of the study can be used for development of heterostructures for mid-infrared light-emitting diodes.

  1. TU-EF-207-02: Spectral Mammography Based on Photon Counting Detectors

    Energy Technology Data Exchange (ETDEWEB)

    Molloi, S. [University of California (United States)

    2015-06-15

    Breast imaging technology is advancing on several fronts. In digital mammography, the major technological trend has been on optimization of approaches for performing combined mammography and tomosynthesis using the same system. In parallel, photon-counting slot-scan mammography is now in clinical use and more efforts are directed towards further development of this approach for spectral imaging. Spectral imaging refers to simultaneous acquisition of two or more energy-windowed images. Depending on the detector and associated electronics, there are a number of ways this can be accomplished. Spectral mammography using photon-counting detectors can suppress electronic noise and importantly, it enables decomposition of the image into various material compositions of interest facilitating quantitative imaging. Spectral imaging can be particularly important in intravenously injected contrast mammography and eventually tomosynthesis. The various approaches and applications of spectral mammography are discussed. Digital breast tomosynthesis relies on the mechanical movement of the x-ray tube to acquire a number of projections in a predefined arc, typically from 9 to 25 projections over a scan angle of +/−7.5 to 25 degrees depending on the particular system. The mechanical x-ray tube motion requires relatively long acquisition time, typically between 3.7 to 25 seconds depending on the system. Moreover, mechanical scanning may have an effect on the spatial resolution due to internal x-ray filament or external mechanical vibrations. New x-ray source arrays have been developed and they are aimed at replacing the scanned x-ray tube for improved acquisition time and potentially for higher spatial resolution. The potential advantages and challenges of this approach are described. Combination of digital mammography and tomosynthesis in a single system places increased demands on certain functional aspects of the detector and overall performance, particularly in the tomosynthesis

  2. TU-EF-207-02: Spectral Mammography Based on Photon Counting Detectors

    International Nuclear Information System (INIS)

    Molloi, S.

    2015-01-01

    Breast imaging technology is advancing on several fronts. In digital mammography, the major technological trend has been on optimization of approaches for performing combined mammography and tomosynthesis using the same system. In parallel, photon-counting slot-scan mammography is now in clinical use and more efforts are directed towards further development of this approach for spectral imaging. Spectral imaging refers to simultaneous acquisition of two or more energy-windowed images. Depending on the detector and associated electronics, there are a number of ways this can be accomplished. Spectral mammography using photon-counting detectors can suppress electronic noise and importantly, it enables decomposition of the image into various material compositions of interest facilitating quantitative imaging. Spectral imaging can be particularly important in intravenously injected contrast mammography and eventually tomosynthesis. The various approaches and applications of spectral mammography are discussed. Digital breast tomosynthesis relies on the mechanical movement of the x-ray tube to acquire a number of projections in a predefined arc, typically from 9 to 25 projections over a scan angle of +/−7.5 to 25 degrees depending on the particular system. The mechanical x-ray tube motion requires relatively long acquisition time, typically between 3.7 to 25 seconds depending on the system. Moreover, mechanical scanning may have an effect on the spatial resolution due to internal x-ray filament or external mechanical vibrations. New x-ray source arrays have been developed and they are aimed at replacing the scanned x-ray tube for improved acquisition time and potentially for higher spatial resolution. The potential advantages and challenges of this approach are described. Combination of digital mammography and tomosynthesis in a single system places increased demands on certain functional aspects of the detector and overall performance, particularly in the tomosynthesis

  3. Quantitative contrast-enhanced spectral mammography based on photon-counting detectors: A feasibility study.

    Science.gov (United States)

    Ding, Huanjun; Molloi, Sabee

    2017-08-01

    To investigate the feasibility of accurate quantification of iodine mass thickness in contrast-enhanced spectral mammography. A computer simulation model was developed to evaluate the performance of a photon-counting spectral mammography system in the application of contrast-enhanced spectral mammography. A figure-of-merit (FOM), which was defined as the decomposed iodine signal-to-noise ratio (SNR) with respect to the square root of the mean glandular dose (MGD), was chosen to optimize the imaging parameters, in terms of beam energy, splitting energy, and prefiltrations for breasts of various thicknesses and densities. Experimental phantom studies were also performed using a beam energy of 40 kVp and a splitting energy of 34 keV with 3 mm Al prefiltration. A two-step calibration method was investigated to quantify the iodine mass thickness, and was validated using phantoms composed of a mixture of glandular and adipose materials, for various breast thicknesses and densities. Finally, the traditional dual-energy log-weighted subtraction method was also studied as a comparison. The measured iodine signal from both methods was compared to the known value to characterize the quantification accuracy and precision. The optimal imaging parameters, which lead to the highest FOM, were found at a beam energy between 42 and 46 kVp with a splitting energy at 34 keV. The optimal tube voltage decreased as the breast thickness or the Al prefiltration increased. The proposed quantification method was able to measure iodine mass thickness on phantoms of various thicknesses and densities with high accuracy. The root-mean-square (RMS) error for cm-scale lesion phantoms was estimated to be 0.20 mg/cm 2 . The precision of the technique, characterized by the standard deviation of the measurements, was estimated to be 0.18 mg/cm 2 . The traditional weighted subtraction method also predicted a linear correlation between the measured signal and the known iodine mass thickness. However

  4. Improving Recommendations in Tag-based Systems with Spectral Clustering of Tag Neighbors

    DEFF Research Database (Denmark)

    Pan, Rong; Xu, Guandong; Dolog, Peter

    2012-01-01

    Tag as a useful metadata reflects the collaborative and conceptual features of documents in social collaborative annotation systems. In this paper, we propose a collaborative approach for expanding tag neighbors and investigate the spectral clustering algorithm to filter out noisy tag neighbors...... in order to get appropriate recommendation for users. The preliminary experiments have been conducted on MovieLens dataset to compare our proposed approach with the traditional collaborative filtering recommendation approach and naive tag neighbors expansion approach in terms of precision, and the result...... demonstrates that our approach could considerably improve the performance of recommendations....

  5. Classification of Error-Diffused Halftone Images Based on Spectral Regression Kernel Discriminant Analysis

    Directory of Open Access Journals (Sweden)

    Zhigao Zeng

    2016-01-01

    Full Text Available This paper proposes a novel algorithm to solve the challenging problem of classifying error-diffused halftone images. We firstly design the class feature matrices, after extracting the image patches according to their statistics characteristics, to classify the error-diffused halftone images. Then, the spectral regression kernel discriminant analysis is used for feature dimension reduction. The error-diffused halftone images are finally classified using an idea similar to the nearest centroids classifier. As demonstrated by the experimental results, our method is fast and can achieve a high classification accuracy rate with an added benefit of robustness in tackling noise.

  6. A deflation based parallel algorithm for spectral element solution of the incompressible Navier-Stokes equations

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, P.F. [Brown Univ., Providence, RI (United States)

    1996-12-31

    Efficient solution of the Navier-Stokes equations in complex domains is dependent upon the availability of fast solvers for sparse linear systems. For unsteady incompressible flows, the pressure operator is the leading contributor to stiffness, as the characteristic propagation speed is infinite. In the context of operator splitting formulations, it is the pressure solve which is the most computationally challenging, despite its elliptic origins. We seek to improve existing spectral element iterative methods for the pressure solve in order to overcome the slow convergence frequently observed in the presence of highly refined grids or high-aspect ratio elements.

  7. Spectral properties and ASTER-based alteration mapping of Masahim volcano facies, SE Iran

    Science.gov (United States)

    Tayebi, Mohammad H.; Tangestani, Majid H.; Vincent, Robert K.; Neal, Devin

    2014-10-01

    This study applies Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data and the Mixture Tuned Matched Filtering (MTMF) algorithm to map the sub-pixel distribution of alteration minerals associated with the Masahim volcano, SE Iran for understanding the spatial relationship between alteration minerals and volcano facies. Investigations of the alteration mineralogy were conducted using field-spectroscopy, X-ray diffraction (XRD) analysis and ASTER Short Wave Infrared (SWIR) spectral data. In order to spectrally characterize the stratovolcano deposits, lithological units and alteration minerals, the volcano was divided into three facies: the Central, Proximal, and Medial-distal facies. The reflectance spectra of rock samples show absorption features of a number of minerals including white mica, kaolinite, montmorillonite, illite, goethite, hematite, jarosite, opal, and chlorite. The end-members of key alteration minerals including sericite (phyllic zone), kaolinite (argillic zone) and chlorite (propylitic zone) were extracted from imagery using the Pixel Purity Index (PPI) method and were used to map alteration minerals. Accuracy assessment through field observations was used to verify the fraction maps. The results showed that most prominent altered rocks situated at the central facies of volcano. The alteration minerals were discriminated with the coefficient of determination (R2) of 0.74, 0.81, and 0.68 for kaolinite, sericite, and chlorite, respectively. The results of this study have the potential to refine the map of alteration zones in the Masahim volcano.

  8. An Excel‐based implementation of the spectral method of action potential alternans analysis

    Science.gov (United States)

    Pearman, Charles M.

    2014-01-01

    Abstract Action potential (AP) alternans has been well established as a mechanism of arrhythmogenesis and sudden cardiac death. Proper interpretation of AP alternans requires a robust method of alternans quantification. Traditional methods of alternans analysis neglect higher order periodicities that may have greater pro‐arrhythmic potential than classical 2:1 alternans. The spectral method of alternans analysis, already widely used in the related study of microvolt T‐wave alternans, has also been used to study AP alternans. Software to meet the specific needs of AP alternans analysis is not currently available in the public domain. An AP analysis tool is implemented here, written in Visual Basic for Applications and using Microsoft Excel as a shell. This performs a sophisticated analysis of alternans behavior allowing reliable distinction of alternans from random fluctuations, quantification of alternans magnitude, and identification of which phases of the AP are most affected. In addition, the spectral method has been adapted to allow detection and quantification of higher order regular oscillations. Analysis of action potential morphology is also performed. A simple user interface enables easy import, analysis, and export of collated results. PMID:25501439

  9. An Excel-based implementation of the spectral method of action potential alternans analysis.

    Science.gov (United States)

    Pearman, Charles M

    2014-12-01

    Action potential (AP) alternans has been well established as a mechanism of arrhythmogenesis and sudden cardiac death. Proper interpretation of AP alternans requires a robust method of alternans quantification. Traditional methods of alternans analysis neglect higher order periodicities that may have greater pro-arrhythmic potential than classical 2:1 alternans. The spectral method of alternans analysis, already widely used in the related study of microvolt T-wave alternans, has also been used to study AP alternans. Software to meet the specific needs of AP alternans analysis is not currently available in the public domain. An AP analysis tool is implemented here, written in Visual Basic for Applications and using Microsoft Excel as a shell. This performs a sophisticated analysis of alternans behavior allowing reliable distinction of alternans from random fluctuations, quantification of alternans magnitude, and identification of which phases of the AP are most affected. In addition, the spectral method has been adapted to allow detection and quantification of higher order regular oscillations. Analysis of action potential morphology is also performed. A simple user interface enables easy import, analysis, and export of collated results. © 2014 The Author. Physiological Reports published by Wiley Periodicals, Inc. on behalf of the American Physiological Society and The Physiological Society.

  10. Broad spectral response photodetector based on individual tin-doped CdS nanowire

    Directory of Open Access Journals (Sweden)

    Weichang Zhou

    2014-12-01

    Full Text Available High purity and tin-doped 1D CdS micro/nano-structures were synthesized by a convenient thermal evaporation method. SEM, EDS, XRD and TEM were used to examine the morphology, composition, phase structure and crystallinity of as-prepared samples. Raman spectrum was used to confirm tin doped into CdS effectively. The effect of impurity on the photoresponse properties of photodetectors made from these as-prepared pure and tin-doped CdS micro/nano-structures under excitation of light with different wavelength was investigated. Various photoconductive parameters such as responsivity, external quantum efficiency, response time and stability were analyzed to evaluate the advantage of doped nanowires and the feasibility for photodetector application. Comparison with pure CdS nanobelt, the tin-doped CdS nanowires response to broader spectral range while keep the excellect photoconductive parameters. Both trapped state induced by tin impurity and optical whispering gallery mode microcavity effect in the doped CdS nanowires contribute to the broader spectral response. The micro-photoluminescence was used to confirm the whispering gallery mode effect and deep trapped state in the doped CdS nanowires.

  11. Research on the strong optical feedback effects based on spectral analysis method

    Science.gov (United States)

    Zeng, Zhaoli; Qu, XueMin; Li, Weina; Zhang, Min; Wang, Hao; Li, Tuo

    2018-01-01

    The strong optical feedback has the advantage of generating high resolution fringes. However, these feedback fringes usually seem like the noise signal when the feedback level is high. This defect severely limits its practical application. In this paper, the generation mechanism of noise fringes with strong optical feedback is studied by using spectral analysis method. The spectral analysis results show that, in most cases, the noise-like fringes are observed owing to the strong multiple high-order feedback. However, at certain feedback cavity condition, there may be only one high-order feedback beam goes back to the laser cavity, the noise-like fringes can change to the cosine-like fringes. And the resolution of this fringe is dozens times than that of the weak optical feedback. This research provides a method to obtain high resolution cosine-like fringes rather than noise signal in the strong optical feedback, which makes it possible to be used in nanoscale displacement measurements.

  12. Augmenting the spectral efficiency of enhanced PAM-DMT-based optical wireless communications.

    Science.gov (United States)

    Islim, Mohamed Sufyan; Haas, Harald

    2016-05-30

    The energy efficiency of pulse-amplitude-modulated discrete multitone modulation (PAM-DMT) decreases as the modulation order of M-PAM modulation increases. Enhanced PAM-DMT (ePAM-DMT) was proposed as a solution to the reduced energy efficiency of PAM-DMT. This was achieved by allowing multiple streams of PAM-DMT to be superimposed and successively demodulated at the receiver side. In order to maintain a distortion-free unipolar ePAM-DMT system, the multiple time-domain PAM-DMT streams are required to be aligned. However, aligning the antisymmetry in ePAM-DMT is complex and results in efficiency losses. In this paper, a novel simplified method to apply the superposition modulation on M-PAM modulated discrete multitone (DMT) is introduced. Contrary to ePAM-DMT, the signal generation of the proposed system, termed augmented spectral efficiency discrete multitone (ASE-DMT), occurs in the frequency domain. This results in an improved spectral and energy efficiency. The analytical bit error rate (BER) performance bound of the proposed system is derived and compared with Monte-Carlo simulations. The system performance is shown to offer significant electrical and optical energy savings compared with ePAM-DMT and DC-biased optical orthogonal frequency division multiplexing (DCO-OFDM).

  13. A region-based segmentation method for ultrasound images in HIFU therapy

    International Nuclear Information System (INIS)

    Zhang, Dong; Liu, Yu; Yang, Yan; Xu, Menglong; Yan, Yu; Qin, Qianqing

    2016-01-01

    Purpose: Precisely and efficiently locating a tumor with less manual intervention in ultrasound-guided high-intensity focused ultrasound (HIFU) therapy is one of the keys to guaranteeing the therapeutic result and improving the efficiency of the treatment. The segmentation of ultrasound images has always been difficult due to the influences of speckle, acoustic shadows, and signal attenuation as well as the variety of tumor appearance. The quality of HIFU guidance images is even poorer than that of conventional diagnostic ultrasound images because the ultrasonic probe used for HIFU guidance usually obtains images without making contact with the patient’s body. Therefore, the segmentation becomes more difficult. To solve the segmentation problem of ultrasound guidance image in the treatment planning procedure for HIFU therapy, a novel region-based segmentation method for uterine fibroids in HIFU guidance images is proposed. Methods: Tumor partitioning in HIFU guidance image without manual intervention is achieved by a region-based split-and-merge framework. A new iterative multiple region growing algorithm is proposed to first split the image into homogenous regions (superpixels). The features extracted within these homogenous regions will be more stable than those extracted within the conventional neighborhood of a pixel. The split regions are then merged by a superpixel-based adaptive spectral clustering algorithm. To ensure the superpixels that belong to the same tumor can be clustered together in the merging process, a particular construction strategy for the similarity matrix is adopted for the spectral clustering, and the similarity matrix is constructed by taking advantage of a combination of specifically selected first-order and second-order texture features computed from the gray levels and the gray level co-occurrence matrixes, respectively. The tumor region is picked out automatically from the background regions by an algorithm according to a priori

  14. A region-based segmentation method for ultrasound images in HIFU therapy

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Dong, E-mail: dongz@whu.edu.cn; Liu, Yu; Yang, Yan; Xu, Menglong; Yan, Yu [School of Physics and Technology, Wuhan University, Wuhan 430072 (China); Qin, Qianqing [State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University, Wuhan 430072 (China)

    2016-06-15

    Purpose: Precisely and efficiently locating a tumor with less manual intervention in ultrasound-guided high-intensity focused ultrasound (HIFU) therapy is one of the keys to guaranteeing the therapeutic result and improving the efficiency of the treatment. The segmentation of ultrasound images has always been difficult due to the influences of speckle, acoustic shadows, and signal attenuation as well as the variety of tumor appearance. The quality of HIFU guidance images is even poorer than that of conventional diagnostic ultrasound images because the ultrasonic probe used for HIFU guidance usually obtains images without making contact with the patient’s body. Therefore, the segmentation becomes more difficult. To solve the segmentation problem of ultrasound guidance image in the treatment planning procedure for HIFU therapy, a novel region-based segmentation method for uterine fibroids in HIFU guidance images is proposed. Methods: Tumor partitioning in HIFU guidance image without manual intervention is achieved by a region-based split-and-merge framework. A new iterative multiple region growing algorithm is proposed to first split the image into homogenous regions (superpixels). The features extracted within these homogenous regions will be more stable than those extracted within the conventional neighborhood of a pixel. The split regions are then merged by a superpixel-based adaptive spectral clustering algorithm. To ensure the superpixels that belong to the same tumor can be clustered together in the merging process, a particular construction strategy for the similarity matrix is adopted for the spectral clustering, and the similarity matrix is constructed by taking advantage of a combination of specifically selected first-order and second-order texture features computed from the gray levels and the gray level co-occurrence matrixes, respectively. The tumor region is picked out automatically from the background regions by an algorithm according to a priori

  15. The CHESS Survey of the L1157-B1 Shock Region: CO Spectral Signatures of Jet-driven Bow Shocks

    Science.gov (United States)

    Lefloch, B.; Cabrit, S.; Busquet, G.; Codella, C.; Ceccarelli, C.; Cernicharo, J.; Pardo, J. R.; Benedettini, M.; Lis, D. C.; Nisini, B.

    2012-10-01

    The unprecedented sensitivity of Herschel coupled with the high resolution of the HIFI spectrometer permits studies of the intensity-velocity relationship I(v) in molecular outflows, over a higher excitation range than possible up to now. Over the course of the CHESS Key Program, we have observed toward the bright bow shock region L1157-B1, the CO rotational transitions between J = 5-4 and J = 16-15 with HIFI, and the J = 1-0, 2-1, and 3-2 with the IRAM 30 m and the Caltech Submillimeter Observatory telescopes. We find that all the line profiles I CO(v) are well fit by a linear combination of three exponential laws vpropexp (- |v/v 0|) with v 0 = 12.5, 4.4, and 2.5 km s-1. The first component dominates the CO emission at J >= 13, as well as the high-excitation lines of SiO and H2O. The second component dominates for 3 = 105-106 cm-3) close to LTE up to J = 20. We find that the CO J = 2-1 intensity-velocity relation observed in various other molecular outflows is satisfactorily fit by similar exponential laws, which may hold an important clue to their entrainment process.

  16. Very loud speech over simulated environmental noise tends to have a spectral peak in the F1 region

    Science.gov (United States)

    Ternstrom, Sten; Bohman, Mikael; Sodersten, Maria

    2003-04-01

    In some professions, workplace noise appears to be a hazard to the voice, if not to hearing. Several studies have shown that teachers and sports instructors, for example, are more prone to voice problems than average, prompting research on loud voice. Since on-location recordings are in many ways impractical, the running speech of 23 untrained speaker subjects (12 female, 11 male) was instead recorded in several types of loud noise that was presented over high-quality loudspeakers. Using adaptive cancellation techniques, the noise was then removed from the recordings, thus exposing the strained voices for analysis. The experiment produced a large body of data, only one aspect of which is reported here. In most subjects, the vowel spectrum as a function of voice SPL showed the expected behavior for low to moderate efforts, but developed a very pronounced peak in the F1 region at the highest efforts. This peak can be ascribed to the concerted action of several acoustic mechanisms, including source waveform asymmetry, F1 approximating one of the lower partials, and increased formant Q values due to a longer closed phase. [Work supported by the Swedish Council for Working Life and Social Research, Contract No. 2001-0341.

  17. Regional Economic Development Strategy Based Agro-Industries in Key Region Kandangan South of Kalimantan

    Directory of Open Access Journals (Sweden)

    Dewi Siska

    2016-06-01

    Full Text Available Agroindustry has become the main pillar in South Kalimantan development, it can be found in RPJPD 2005-2025. Kandangan mainstay region as one of three leading regions in South Kalimantan which potentially improved to push economy growth through agriculture based industry activity (agroindustry. The concept of agroindustry a side is expected to drive economic growth as well as to realize the equitable distribution of income. This research aims to: (1 identify to economic development of the region in Kandangan mainstay regions, (2 identify the main commodity, (3 identify means of supporting agroindustry, and (4 formulating development strategies based agroindustry region. Entropy analysis shows the development of the economy sufficiently developed in Kandangan mainstay region dominated by the agricultural sector, namely food crops subsector. LQ an SSA analysis shows corn and rice crops become competitive commodities. There are only few of supporting infrastructure agroindustry activities. Strategy formulation in the research is the improvement of infrastructure or infrastructure that can facilitate inter regional connectivity in the region mainstay Kandangan and the government as the leading actor agroindustry development.

  18. A Trust-region-based Sequential Quadratic Programming Algorithm

    DEFF Research Database (Denmark)

    Henriksen, Lars Christian; Poulsen, Niels Kjølstad

    This technical note documents the trust-region-based sequential quadratic programming algorithm used in other works by the authors. The algorithm seeks to minimize a convex nonlinear cost function subject to linear inequalty constraints and nonlinear equality constraints.......This technical note documents the trust-region-based sequential quadratic programming algorithm used in other works by the authors. The algorithm seeks to minimize a convex nonlinear cost function subject to linear inequalty constraints and nonlinear equality constraints....

  19. Examination of Spectral Transformations on Spectral Mixture Analysis

    Science.gov (United States)

    Deng, Y.; Wu, C.

    2018-04-01

    While many spectral transformation techniques have been applied on spectral mixture analysis (SMA), few study examined their necessity and applicability. This paper focused on exploring the difference between spectrally transformed schemes and untransformed scheme to find out which transformed scheme performed better in SMA. In particular, nine spectrally transformed schemes as well as untransformed scheme were examined in two study areas. Each transformed scheme was tested 100 times using different endmember classes' spectra under the endmember model of vegetation- high albedo impervious surface area-low albedo impervious surface area-soil (V-ISAh-ISAl-S). Performance of each scheme was assessed based on mean absolute error (MAE). Statistical analysis technique, Paired-Samples T test, was applied to test the significance of mean MAEs' difference between transformed and untransformed schemes. Results demonstrated that only NSMA could exceed the untransformed scheme in all study areas. Some transformed schemes showed unstable performance since they outperformed the untransformed scheme in one area but weakened the SMA result in another region.

  20. Potential of VIS-NIR-SWIR Spectroscopy from the Chinese Soil Spectral Library for Assessment of Nitrogen Fertilization Rates in the Paddy-Rice Region, China

    Directory of Open Access Journals (Sweden)

    Shuo Li

    2015-05-01

    Full Text Available To meet growing food demand with limited land and reduced environmental impact, soil testing and formulated fertilization methods have been widely adopted around the world. However, conventional technology for investigating nitrogen fertilization rates (NFR is time consuming and expensive. Here, we evaluated the use of visible near-infrared shortwave-infrared (VIS-NIR-SWIR: 400–2500 nm spectroscopy for the assessment of NFR to provide necessary information for fast, cost-effective and precise fertilization rating. Over 2000 samples were collected from paddy-rice fields in 10 Chinese provinces; samples were added to the Chinese Soil Spectral Library (CSSL. Two kinds of modeling strategies for NFR, quantitative estimation of soil N prior to classification and qualitative by classification, were employed using partial least squares regression (PLSR, locally weighted regression (LWR, and support vector machine discriminant analogy (SVMDA. Overall, both LWR and SVMDA had moderate accuracies with Cohen’s kappa coefficients of 0.47 and 0.48, respectively, while PLSR had fair accuracy (0.37. We conclude that VIS-NIR-SWIR spectroscopy coupled with the CSSL appears to be a viable, rapid means for the assessment of NFR in paddy-rice soil. Based on qualitative classification of soil spectral data only, it is recommended that the SVMDA be adopted for rapid implementation.

  1. WE-DE-207B-01: Optimization for Contrast-Enhanced Spectral Mammography Based On Photon-Counting Detectors

    Energy Technology Data Exchange (ETDEWEB)

    Ding, H; Molloi, S [University of California, Irvine, CA (United States)

    2016-06-15

    Purpose: To investigate the feasibility of optimizing the imaging parameters for contrast-enhanced spectral mammography based on Si strip photon-counting detectors. Methods: A computer simulation model using polyenergetic spectra from a tungsten anode x-ray tube and a Si-based photon-counting detector was evaluated for contrast-enhanced spectral mammography. The simulation traces the emission of photons from the x-ray source, attenuation through the breast and subsequent absorption in the detector. The breast was modeled as a mixture of adipose and mammary gland tissues with a breast density of 30%. A 4 mm iodine signal with a concentration of 4 mg/ml was used to simulate the enhancement of a lesion. Quantum efficiency of the detector was calculated based on the effective attenuation length in the Si strips. The figure-of-merit (FOM), which was defined as the decomposed iodine signal-to-noise ratio (SNR) with respect to the square root of the mean glandular dose (MGD), was chosen to optimize the imaging parameters, in terms of beam energy, splitting energy, and pre-filtrations for breast of various thicknesses and densities. Results: The optimal imaging parameters, which lead to the highest FOM, were found at a beam energy of 45 kVp with a splitting energy at 34 keV for an averaged breast thickness of 4 cm with a standard 0.75 mm Al pre-filtration. The optimal tube voltage varied slightly from 46 to 44 kVp as the breast thickness increases from 2 to 8 cm. The optimal tube voltage decreased to 42 kVp when the Al pre-filtration was increased to 3 mm. Conclusion: This simulation study predicted the optimal imaging parameters for application of photon-counting spectral mammography to contrast-enhanced imaging. The simulation results laid the ground work for future phantom and clinical studies. Grant funding from Philips Medical Systems.

  2. THE CHESS SURVEY OF THE L1157-B1 SHOCK REGION: CO SPECTRAL SIGNATURES OF JET-DRIVEN BOW SHOCKS

    International Nuclear Information System (INIS)

    Lefloch, B.; Codella, C.; Ceccarelli, C.; Cabrit, S.; Busquet, G.; Benedettini, M.; Cernicharo, J.; Pardo, J. R.; Lis, D. C.; Nisini, B.

    2012-01-01

    The unprecedented sensitivity of Herschel coupled with the high resolution of the HIFI spectrometer permits studies of the intensity-velocity relationship I(v) in molecular outflows, over a higher excitation range than possible up to now. Over the course of the CHESS Key Program, we have observed toward the bright bow shock region L1157-B1, the CO rotational transitions between J = 5-4 and J = 16-15 with HIFI, and the J = 1-0, 2-1, and 3-2 with the IRAM 30 m and the Caltech Submillimeter Observatory telescopes. We find that all the line profiles I CO (v) are well fit by a linear combination of three exponential laws ∝exp (– |v/v 0 |) with v 0 = 12.5, 4.4, and 2.5 km s –1 . The first component dominates the CO emission at J ≥ 13, as well as the high-excitation lines of SiO and H 2 O. The second component dominates for 3 ≤ J up ≤ 10 and the third one for J up ≤ 2. We show that these exponentials are the signature of quasi-isothermal shocked gas components: the impact of the jet against the L1157-B1 bow shock (T k ≅ 210 K), the walls of the outflow cavity associated with B1 (T k ≅ 64 K), and the older cavity L1157-B2 (T k ≅ 23 K), respectively. Analysis of the CO line flux in the large-velocity gradient approximation further shows that the emission arises from dense gas (n(H 2 ) ≥ 10 5 -10 6 cm –3 ) close to LTE up to J = 20. We find that the CO J = 2-1 intensity-velocity relation observed in various other molecular outflows is satisfactorily fit by similar exponential laws, which may hold an important clue to their entrainment process.

  3. Spectral zone selection methodology for pebble bed reactors

    International Nuclear Information System (INIS)

    Mphahlele, Ramatsemela; Ougouag, Abderrafi M.; Ivanov, Kostadin N.; Gougar, Hans D.

    2011-01-01

    A methodology is developed for determining boundaries of spectral zones for pebble bed reactors. A spectral zone is defined as a region made up of a number of nodes whose characteristics are collectively similar and that are assigned the same few-group diffusion constants. The spectral zones are selected in such a manner that the difference (error) between the reference transport solution and the diffusion code solution takes a minimum value. This is achieved by choosing spectral zones through optimally minimizing this error. The objective function for the optimization algorithm is the total reaction rate error, which is defined as the sum of the leakage, absorption and fission reaction rates errors in each zone. The selection of these spectral zones is such that the core calculation results based on diffusion theory are within an acceptable tolerance as compared to a proper transport reference solution. Through this work, a consistent approach for identifying spectral zones that yield more accurate diffusion results is introduced.

  4. Multiple-region directed functional connectivity based on phase delays.

    Science.gov (United States)

    Goelman, Gadi; Dan, Rotem

    2017-03-01

    Network analysis is increasingly advancing the field of neuroimaging. Neural networks are generally constructed from pairwise interactions with an assumption of linear relations between them. Here, a high-order statistical framework to calculate directed functional connectivity among multiple regions, using wavelet analysis and spectral coherence has been presented. The mathematical expression for 4 regions was derived and used to characterize a quartet of regions as a linear, combined (nonlinear), or disconnected network. Phase delays between regions were used to obtain network's temporal hierarchy and directionality. The validity of the mathematical derivation along with the effects of coupling strength and noise on its outcomes were studied by computer simulations of the Kuramoto model. The simulations demonstrated correct directionality for a large range of coupling strength and low sensitivity to Gaussian noise compared with pairwise coherences. The analysis was applied to resting-state fMRI data of 40 healthy young subjects to characterize the ventral visual system, motor system and default mode network (DMN). It was shown that the ventral visual system was predominantly composed of linear networks while the motor system and the DMN were composed of combined (nonlinear) networks. The ventral visual system exhibits its known temporal hierarchy, the motor system exhibits center ↔ out hierarchy and the DMN has dorsal ↔ ventral and anterior ↔ posterior organizations. The analysis can be applied in different disciplines such as seismology, or economy and in a variety of brain data including stimulus-driven fMRI, electrophysiology, EEG, and MEG, thus open new horizons in brain research. Hum Brain Mapp 38:1374-1386, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  5. Versatile high-repetition-rate phase-locked chopper system for fast timing experiments in the vacuum ultraviolet and x-ray spectral region

    Energy Technology Data Exchange (ETDEWEB)

    Plogmaker, Stefan; Johansson, Erik M. J.; Rensmo, Haakan; Feifel, Raimund; Siegbahn, Hans [Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala (Sweden); Linusson, Per [Department of Physics, Stockholm University, AlbaNova University Center, SE-106 91 Stockholm (Sweden); Eland, John H. D. [Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala (Sweden); Department of Chemistry, Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford OX1 3QZ (United Kingdom); Baker, Neville [Department of Chemistry, Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford OX1 3QZ (United Kingdom)

    2012-01-15

    A novel light chopper system for fast timing experiments in the vacuum-ultraviolet (VUV) and x-ray spectral region has been developed. It can be phase-locked and synchronized with a synchrotron radiation storage ring, accommodating repetition rates in the range of {approx}8 to {approx}120 kHz by choosing different sets of apertures and subharmonics of the ring frequency (MHz range). Also the opening time of the system can be varied from some nanoseconds to several microseconds to meet the needs of a broad range of applications. Adjusting these parameters, the device can be used either for the generation of single light pulses or pulse packages from a microwave driven, continuous He gas discharge lamp or from storage rings which are otherwise often considered as quasi-continuous light sources. This chopper can be utilized for many different kinds of experiments enabling, for example, unambiguous time-of-flight (TOF) multi-electron coincidence studies of atoms and molecules excited by a single light pulse as well as time-resolved visible laser pump x-ray probe electron spectroscopy of condensed matter in the valence and core level region.

  6. GOSAT TIR spectral validation with High/Low temperature target using Aircraft base-FTS S-HIS

    Science.gov (United States)

    Kataoka, F.; Knuteson, R.; Taylor, J. K.; Kuze, A.; Shiomi, K.; Suto, H.; Yoshida, J.

    2017-12-01

    The Greenhouse gases Observing SATellite (GOSAT) was launched on January 2009. The GOSAT is equipped with TANSO-FTS (Fourier-Transform Spectrometer), which observe reflected solar radiation from the Earth's surface with shortwave infrared (SWIR) band and thermal emission from the Earth's surface and atmosphere with thermal infrared (TIR) band. The TIR band cover wide spectral range (650 - 1800 [cm-1]) with a high spectral resolution (0.2 [cm-1]). The TIR spectral information provide vertical distribution of CO2 and CH4. GOSAT has been operation more than eight years. In this long operation, GOSAT had experienced two big accidents; Rotation of one of the solar paddles stopped and sudden TANSO-FTS operation stop in May 2014 and cryocooler shutdown and restart in August - September 2015. These events affected the operation condition of the TIR photo-conductive (PC)-MCT detector. FTS technology using multiplex wide spectra needs wide dynamic range. PC detector has nonlinearity. Its correction needs accurate estimation of time-dependent offset. In current TIR Level 1B product version (V201), the non-photon level offset (Vdc_offset) estimated from on-orbit deep space calibration data and pre-launch background radiation model. But the background radiation and detector temperature have changed after cryocooler shutdown events. These changes are too small to detect from onboard temperature sensors. The next TIR Level 1B product uses cross calibration data together with deep space calibration data and instrument radiation model has been updated. This work describes the evaluation of new TIR Level 1B spectral quality with aircraft-based FTS; Scanning High-resolution Interferometer Sounder (S-HIS). The S-HIS mounted on the high-altitude ER-2 aircraft and flew at about 20km altitude. Because the observation geometry of GOSAT and S-HIS are quite different, we used the double difference method using atmospheric transfer model. GOSAT TIR band cover wide dynamic range, so we check

  7. THE CHESS SURVEY OF THE L1157-B1 SHOCK REGION: CO SPECTRAL SIGNATURES OF JET-DRIVEN BOW SHOCKS

    Energy Technology Data Exchange (ETDEWEB)

    Lefloch, B.; Codella, C.; Ceccarelli, C. [UJF-Grenoble 1/CNRS-INSU, Institut de Planetologie et dAstrophysique de Grenoble (IPAG) UMR 5274, Grenoble, F-38041 (France); Cabrit, S. [Observatoire de Paris, LERMA, UMR 8112 du CNRS, ENS, UPMC, UCP, 61 Av. de l' Observatoire, F-75014 Paris (France); Busquet, G.; Benedettini, M. [INAF, Istituto di Astrofisica e Planetologia Spaziali, Via Fosso del Cavaliere 100, I-00133 Roma (Italy); Cernicharo, J.; Pardo, J. R. [Centro de Astrobiologia, INTA, Ctra de Torrejon a Ajalvir, km 4, E-28850 Torrejon de Ardoz, E-28850 Madrid (Spain); Lis, D. C. [California Institute of Technology, Cahill Center for Astronomy and Astrophysics 301-17, Pasadena, CA 91125 (United States); Nisini, B., E-mail: lefloch@obs.ujf-grenoble.fr [INAF, Osservatorio Astronomico di Roma, Via di Frascati 33, I-00040 Monte, Porzio Catone (Italy)

    2012-10-01

    The unprecedented sensitivity of Herschel coupled with the high resolution of the HIFI spectrometer permits studies of the intensity-velocity relationship I(v) in molecular outflows, over a higher excitation range than possible up to now. Over the course of the CHESS Key Program, we have observed toward the bright bow shock region L1157-B1, the CO rotational transitions between J = 5-4 and J = 16-15 with HIFI, and the J = 1-0, 2-1, and 3-2 with the IRAM 30 m and the Caltech Submillimeter Observatory telescopes. We find that all the line profiles I{sub CO}(v) are well fit by a linear combination of three exponential laws {proportional_to}exp (- |v/v{sub 0}|) with v{sub 0} = 12.5, 4.4, and 2.5 km s{sup -1}. The first component dominates the CO emission at J {>=} 13, as well as the high-excitation lines of SiO and H{sub 2}O. The second component dominates for 3 {<=} J{sub up} {<=} 10 and the third one for J{sub up} {<=} 2. We show that these exponentials are the signature of quasi-isothermal shocked gas components: the impact of the jet against the L1157-B1 bow shock (T{sub k} {approx_equal} 210 K), the walls of the outflow cavity associated with B1 (T{sub k} {approx_equal} 64 K), and the older cavity L1157-B2 (T{sub k} {approx_equal} 23 K), respectively. Analysis of the CO line flux in the large-velocity gradient approximation further shows that the emission arises from dense gas (n(H{sub 2}) {>=} 10{sup 5}-10{sup 6} cm{sup -3}) close to LTE up to J = 20. We find that the CO J = 2-1 intensity-velocity relation observed in various other molecular outflows is satisfactorily fit by similar exponential laws, which may hold an important clue to their entrainment process.

  8. Spectrally dependent photovoltages in Schottky photodiode based on (100) B-doped diamond

    International Nuclear Information System (INIS)

    Čermák, Jan; Rezek, Bohuslav; Koide, Yasuo; Takeuchi, Daisuke

    2014-01-01

    Spectrally and spatially resolved photovoltages were measured by Kelvin probe force microscopy (KPFM) on a Schottky photo-diode made of a 4 nm thin tungsten-carbide (WC) layer on a 500 nm oxygen-terminated boron-doped diamond epitaxial layer (O-BDD) that was grown on a Ib (100) diamond substrate. The diode was grounded by the sideways ohmic contact (Ti/WC), and the semitransparent Schottky contact was let unconnected. The electrical potentials across the device were measured in dark (only 650 nm LED of KPFM being on), under broad-band white light (halogen lamp), UV (365 nm diode), and deep ultraviolet (deuterium lamp) illumination. Illumination induced shift of the electrical potential remains within 210 mV. We propose that the photovoltage actually corresponds to a shift of Fermi level inside the BDD channel and thereby explains orders of magnitude changes in photocurrent

  9. Spectrally dependent photovoltages in Schottky photodiode based on (100) B-doped diamond

    Science.gov (United States)

    Čermák, Jan; Koide, Yasuo; Takeuchi, Daisuke; Rezek, Bohuslav

    2014-02-01

    Spectrally and spatially resolved photovoltages were measured by Kelvin probe force microscopy (KPFM) on a Schottky photo-diode made of a 4 nm thin tungsten-carbide (WC) layer on a 500 nm oxygen-terminated boron-doped diamond epitaxial layer (O-BDD) that was grown on a Ib (100) diamond substrate. The diode was grounded by the sideways ohmic contact (Ti/WC), and the semitransparent Schottky contact was let unconnected. The electrical potentials across the device were measured in dark (only 650 nm LED of KPFM being on), under broad-band white light (halogen lamp), UV (365 nm diode), and deep ultraviolet (deuterium lamp) illumination. Illumination induced shift of the electrical potential remains within 210 mV. We propose that the photovoltage actually corresponds to a shift of Fermi level inside the BDD channel and thereby explains orders of magnitude changes in photocurrent.

  10. Spectrally-resolved response properties of the three most advanced FRET based fluorescent protein voltage probes.

    Directory of Open Access Journals (Sweden)

    Hiroki Mutoh

    Full Text Available Genetically-encoded optical probes for membrane potential hold the promise of monitoring electrical signaling of electrically active cells such as specific neuronal populations in intact brain tissue. The most advanced class of these probes was generated by molecular fusion of the voltage sensing domain (VSD of Ci-VSP with a fluorescent protein (FP pair. We quantitatively compared the three most advanced versions of these probes (two previously reported and one new variant, each involving a spectrally distinct tandem of FPs. Despite these different FP tandems and dissimilarities within the amino acid sequence linking the VSD to the FPs, the amplitude and kinetics of voltage dependent fluorescence changes were surprisingly similar. However, each of these fluorescent probes has specific merits when considering different potential applications.

  11. Beam alignment based on two-dimensional power spectral density of a near-field image.

    Science.gov (United States)

    Wang, Shenzhen; Yuan, Qiang; Zeng, Fa; Zhang, Xin; Zhao, Junpu; Li, Kehong; Zhang, Xiaolu; Xue, Qiao; Yang, Ying; Dai, Wanjun; Zhou, Wei; Wang, Yuanchen; Zheng, Kuixing; Su, Jingqin; Hu, Dongxia; Zhu, Qihua

    2017-10-30

    Beam alignment is crucial to high-power laser facilities and is used to adjust the laser beams quickly and accurately to meet stringent requirements of pointing and centering. In this paper, a novel alignment method is presented, which employs data processing of the two-dimensional power spectral density (2D-PSD) for a near-field image and resolves the beam pointing error relative to the spatial filter pinhole directly. Combining this with a near-field fiducial mark, the operation of beam alignment is achieved. It is experimentally demonstrated that this scheme realizes a far-field alignment precision of approximately 3% of the pinhole size. This scheme adopts only one near-field camera to construct the alignment system, which provides a simple, efficient, and low-cost way to align lasers.

  12. Alignment and integration of complex networks by hypergraph-based spectral clustering

    Science.gov (United States)

    Michoel, Tom; Nachtergaele, Bruno

    2012-11-01

    Complex networks possess a rich, multiscale structure reflecting the dynamical and functional organization of the systems they model. Often there is a need to analyze multiple networks simultaneously, to model a system by more than one type of interaction, or to go beyond simple pairwise interactions, but currently there is a lack of theoretical and computational methods to address these problems. Here we introduce a framework for clustering and community detection in such systems using hypergraph representations. Our main result is a generalization of the Perron-Frobenius theorem from which we derive spectral clustering algorithms for directed and undirected hypergraphs. We illustrate our approach with applications for local and global alignment of protein-protein interaction networks between multiple species, for tripartite community detection in folksonomies, and for detecting clusters of overlapping regulatory pathways in directed networks.

  13. Spectral Neugebauer-based color halftone prediction model accounting for paper fluorescence.

    Science.gov (United States)

    Hersch, Roger David

    2014-08-20

    We present a spectral model for predicting the fluorescent emission and the total reflectance of color halftones printed on optically brightened paper. By relying on extended Neugebauer models, the proposed model accounts for the attenuation by the ink halftones of both the incident exciting light in the UV wavelength range and the emerging fluorescent emission in the visible wavelength range. The total reflectance is predicted by adding the predicted fluorescent emission relative to the incident light and the pure reflectance predicted with an ink-spreading enhanced Yule-Nielsen modified Neugebauer reflectance prediction model. The predicted fluorescent emission spectrum as a function of the amounts of cyan, magenta, and yellow inks is very accurate. It can be useful to paper and ink manufacturers who would like to study in detail the contribution of the fluorescent brighteners and the attenuation of the fluorescent emission by ink halftones.

  14. Spectrally dependent photovoltages in Schottky photodiode based on (100) B-doped diamond

    Energy Technology Data Exchange (ETDEWEB)

    Čermák, Jan, E-mail: cermakj@fzu.cz; Rezek, Bohuslav [Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnická 10, 16200 Prague 6 (Czech Republic); Koide, Yasuo [Sensor Materials Center, National Institute for Material Science (NIMS), 1-1 Namiki, Tsukuba 305-0044 (Japan); Takeuchi, Daisuke [Energy Technology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba 305-8568 (Japan)

    2014-02-07

    Spectrally and spatially resolved photovoltages were measured by Kelvin probe force microscopy (KPFM) on a Schottky photo-diode made of a 4 nm thin tungsten-carbide (WC) layer on a 500 nm oxygen-terminated boron-doped diamond epitaxial layer (O-BDD) that was grown on a Ib (100) diamond substrate. The diode was grounded by the sideways ohmic contact (Ti/WC), and the semitransparent Schottky contact was let unconnected. The electrical potentials across the device were measured in dark (only 650 nm LED of KPFM being on), under broad-band white light (halogen lamp), UV (365 nm diode), and deep ultraviolet (deuterium lamp) illumination. Illumination induced shift of the electrical potential remains within 210 mV. We propose that the photovoltage actually corresponds to a shift of Fermi level inside the BDD channel and thereby explains orders of magnitude changes in photocurrent.

  15. Quasistatic field simulations based on finite elements and spectral methods applied to superconducting magnets

    International Nuclear Information System (INIS)

    Koch, Stephan

    2009-01-01

    problem-tailored discretization approach is based on a geometrical modeling of reduced spatial dimension inside respective domains of symmetry. For the approximation of the electromagnetic fields, orthogonal polynomials along the direction of symmetry are combined with finite element shape functions at the remaining cross-section. This leads to an efficient method providing a high accuracy. The domains of symmetry are embedded into the surrounding region by means of a strong coupling at the discrete level in terms of a domain decomposition approach. Using this strategy, for certain examples a level of accuracy corresponding to numerical models featuring several millions of degrees of freedom in classical finite element methods can be achieved with only one hundred thousand unknowns. This is demonstrated for different examples, e.g., a cylindrical power transformer and the already mentioned accelerator magnet. (orig.)

  16. Rectangular spectral collocation

    KAUST Repository

    Driscoll, Tobin A.; Hale, Nicholas

    2015-01-01

    Boundary conditions in spectral collocation methods are typically imposed by removing some rows of the discretized differential operator and replacing them with others that enforce the required conditions at the boundary. A new approach based upon

  17. Regional Densification of a Global VTEC Model Based on B-Spline Representations

    Science.gov (United States)

    Erdogan, Eren; Schmidt, Michael; Dettmering, Denise; Goss, Andreas; Seitz, Florian; Börger, Klaus; Brandert, Sylvia; Görres, Barbara; Kersten, Wilhelm F.; Bothmer, Volker; Hinrichs, Johannes; Mrotzek, Niclas

    2017-04-01

    The project OPTIMAP is a joint initiative of the Bundeswehr GeoInformation Centre (BGIC), the German Space Situational Awareness Centre (GSSAC), the German Geodetic Research Institute of the Technical University Munich (DGFI-TUM) and the Institute for Astrophysics at the University of Göttingen (IAG). The main goal of the project is the development of an operational tool for ionospheric mapping and prediction (OPTIMAP). Two key features of the project are the combination of different satellite observation techniques (GNSS, satellite altimetry, radio occultations and DORIS) and the regional densification as a remedy against problems encountered with the inhomogeneous data distribution. Since the data from space-geoscientific mission which can be used for modeling ionospheric parameters, such as the Vertical Total Electron Content (VTEC) or the electron density, are distributed rather unevenly over the globe at different altitudes, appropriate modeling approaches have to be developed to handle this inhomogeneity. Our approach is based on a two-level strategy. To be more specific, in the first level we compute a global VTEC model with a moderate regional and spectral resolution which will be complemented in the second level by a regional model in a densification area. The latter is a region characterized by a dense data distribution to obtain a high spatial and spectral resolution VTEC product. Additionally, the global representation means a background model for the regional one to avoid edge effects at the boundaries of the densification area. The presented approach based on a global and a regional model part, i.e. the consideration of a regional densification is called the Two-Level VTEC Model (TLVM). The global VTEC model part is based on a series expansion in terms of polynomial B-Splines in latitude direction and trigonometric B-Splines in longitude direction. The additional regional model part is set up by a series expansion in terms of polynomial B-splines for

  18. Gender Based Violence among Infertile Women In Mara Region ...

    African Journals Online (AJOL)

    This paper examines women to women marriages (nyumba ntobhu) and its relation with gender-based violence (GBV) in Serengeti District of Mara Region. It also explores types of gender-based violence and consequences of women to women marriages among women, girls and children in the society. Both quantitative ...

  19. Region-Based Color Image Indexing and Retrieval

    DEFF Research Database (Denmark)

    Kompatsiaris, Ioannis; Triantafyllou, Evangelia; Strintzis, Michael G.

    2001-01-01

    In this paper a region-based color image indexing and retrieval algorithm is presented. As a basis for the indexing, a novel K-Means segmentation algorithm is used, modified so as to take into account the coherence of the regions. A new color distance is also defined for this algorithm. Based on ....... Experimental results demonstrate the performance of the algorithm. The development of an intelligent image content-based search engine for the World Wide Web is also presented, as a direct application of the presented algorithm....

  20. Climate responses to SATIRE and SIM-based spectral solar forcing in a 3D atmosphere-ocean coupled GCM

    Directory of Open Access Journals (Sweden)

    Wen Guoyong

    2017-01-01

    Full Text Available We apply two reconstructed spectral solar forcing scenarios, one SIM (Spectral Irradiance Monitor based, the other the SATIRE (Spectral And Total Irradiance REconstruction modeled, as inputs to the GISS (Goddard Institute for Space Studies GCMAM (Global Climate Middle Atmosphere Model to examine climate responses on decadal to centennial time scales, focusing on quantifying the difference of climate response between the two solar forcing scenarios. We run the GCMAM for about 400 years with present day trace gas and aerosol for the two solar forcing inputs. We find that the SIM-based solar forcing induces much larger long-term response and 11-year variation in global averaged stratospheric temperature and column ozone. We find significant decreasing trends of planetary albedo for both forcing scenarios in the 400-year model runs. However the mechanisms for the decrease are very different. For SATIRE solar forcing, the decreasing trend of planetary albedo is associated with changes in cloud cover. For SIM-based solar forcing, without significant change in cloud cover on centennial and longer time scales, the apparent decreasing trend of planetary albedo is mainly due to out-of-phase variation in shortwave radiative forcing proxy (downwelling flux for wavelength >330 nm and total solar irradiance (TSI. From the Maunder Minimum to present, global averaged annual mean surface air temperature has a response of ~0.1 °C to SATIRE solar forcing compared to ~0.04 °C to SIM-based solar forcing. For 11-year solar cycle, the global surface air temperature response has 3-year lagged response to either forcing scenario. The global surface air 11-year temperature response to SATIRE forcing is about 0.12 °C, similar to recent multi-model estimates, and comparable to the observational-based evidence. However, the global surface air temperature response to 11-year SIM-based solar forcing is insignificant and inconsistent with observation-based evidence.

  1. Time Lens based Optical Fourier Transformation for All-Optical Signal Processing of Spectrally-Efficient Data

    DEFF Research Database (Denmark)

    Guan, Pengyu; Røge, Kasper Meldgaard; Lillieholm, Mads

    2017-01-01

    We review recent progress in the use of time lens based optical Fourier transformation for advanced all-optical signal processing. A novel time lens based complete optical Fourier transformation (OFT) technique is introduced. This complete OFT is based on two quadratic phase-modulation stages using...... four-wave mixing (FWM), separated by a dispersive medium, which enables time-to-frequency and frequency-to-time conversions simultaneously, thus performing an exchange between the temporal and spectral profiles of the input signal. Using the proposed complete OFT, several advanced all-optical signal......, such as orthogonal frequency division multiplexing (OFDM), Nyquist wavelength-division multiplexing (Nyquist-WDM) and Nyquist optical time division multiplexing (Nyquist-OTDM) signals....

  2. Synthesis, Spectral, and In Vitro Antibacterial Studies of Organosilicon(IV) Complexes with Schiff Bases Derived from Amino Acids.

    Science.gov (United States)

    Singh, Har Lal; Singh, Jangbhadur; Mukherjee, A

    2013-01-01

    The present work stems from our interest in the synthesis, characterization, and antibacterial evaluation of organosilicon(IV) complexes of a class of amino-acid-based Schiff base which have been prepared by the interaction of ethoxytrimethylsilane with the Schiff bases (N OH) in 1 : 1 molar ratio. These complexes have been characterized by elemental analysis, molar conductance, and spectroscopic studies including electronic IR and NMR ((1)H, (13)C, and (29)Si) spectroscopy. The analytical and spectral data suggest trigonal bipyramidal geometry around the silicon atom in the resulting complexes. The ligands and their organosilicon complexes have also been evaluated for in vitro antimicrobial activity against bacteria (Bacillus cereus, Nocardia spp., E. aerogenes, Escherichia coli, Klebsiella spp., and Staphylococcus spp.). The complexes were found to be more potent as compared to the ligands.

  3. Synthesis of metal complexes involving Schiff base ligand with methylenedioxy moiety: spectral, thermal, XRD and antimicrobial studies.

    Science.gov (United States)

    Sundararajan, M L; Jeyakumar, T; Anandakumaran, J; Karpanai Selvan, B

    2014-10-15

    Metal complexes of Zn(II), Cd(II), Ni(II), Cu(II), Fe(III), Co(II), Mn(II) Hg(II), and Ag(I) have been synthesized from Schiff base ligand, prepared by the condensation of 3,4-(methylenedioxy)aniline and 5-bromo salicylaldehyde. All the compounds have been characterized by using elemental analysis, molar conductance, FT-IR, UV-Vis, (1)H NMR, (13)C NMR, mass spectra, powder XRD and thermal analysis (TG/DTA) technique. The elemental analysis suggests the stoichiometry to be 1:1 (metal:ligand). The FT-IR, (1)H NMR, (13)C NMR and UV-Vis spectral data suggest that the ligand coordinate to the metal atom by imino nitrogen and phenolic oxygen as bidentate manner. Mass spectral data further support the molecular mass of the compounds and their structure. Powder XRD indicates the crystalline state and morphology of the ligand and its metal complexes. The thermal behaviors of the complexes prove the presence of lattice as well as coordinated water molecules in the complexes. Melting point supports the thermal stability of all the compounds. The in vitro antimicrobial effects of the synthesized compounds were tested against five bacterial and three fungal species by well diffusion method. Antioxidant activities have also been performed for all the compounds. Metal complexes show more biological activity than the Schiff base. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. Implication of Spectral Characteristic of Chlorite Based on Spectrums SWIR in Nuri Deposit of Tibet

    Science.gov (United States)

    Huang, Z.

    2017-12-01

    This contribution reports the spectral characterization of chlorite in Nuri deposit of Tibet. Nuri Cu polymetallic deposit locates in south rim of Eastern of Gangdise in Tibet. It is presented for large metallogenic scale and special mineralized combination. The study area is underlain extensively by lower Cretaceous rocks of Bima Formation, upper Cretaceous to Paleogene Danshiting Formation and the Quaternary Aeolian Sand. Intrusive bodies, which mainly are quartz diorite, granodiorite, monzonitic granitite, moyite, granite porphyry and so on, feature growth gigantic composite granitic batholith. Distribution of Chlorite is very significant for range and degree of influence of hydrothermal alteration in magmatic hydrothermal deposit. From measuring the spectral of rock and mineral using SVC portable spectrograph, it derived consequence of exists some main altered mineral chlorite. The spectra of chlorite show the absorption features at 1390, 2000, 2250, 2340nm which reflect either O-H stretching vibrations and/or Fe-OH and Mg-OH bending vibrations. Chlorite with Mg-rich shows a strong band at 2324 with a shoulder at 2245nm. The iron-rich chlorite has two absorption features which occur at 2356 and 2256nm. From 110 samples containing chlorite which measured in situ using SVC portable spectrometer, the secondary characteristic absorption wavelengths of chlorite were extracted using TSG software and the diagnosis absorption characteristic of chlorite near 2250nm wavelength is from 2232 to 2266nm. According to the absorption characteristics wavelength position near 2250nm, the samples containing chlorite divided into four categories, i.e. Mg-chlorite whose wavelength less than 2245nm, MgFe-chlorite whose wavelength between 2245 and 2250nm, FeMg-chlorite whose wavelength between 2250 and 2258nm, and Fe-chlorite whose wavelength greater than 2258nm. And then chemical composition of chlorite is analyzed by electron probe with JXA-8230 device which shows that the Fe and

  5. Spectral stratigraphy

    Science.gov (United States)

    Lang, Harold R.

    1991-01-01

    A new approach to stratigraphic analysis is described which uses photogeologic and spectral interpretation of multispectral remote sensing data combined with topographic information to determine the attitude, thickness, and lithology of strata exposed at the surface. The new stratigraphic procedure is illustrated by examples in the literature. The published results demonstrate the potential of spectral stratigraphy for mapping strata, determining dip and strike, measuring and correlating stratigraphic sequences, defining lithofacies, mapping biofacies, and interpreting geological structures.

  6. A framework of region-based dynamic image fusion

    Institute of Scientific and Technical Information of China (English)

    WANG Zhong-hua; QIN Zheng; LIU Yu

    2007-01-01

    A new framework of region-based dynamic image fusion is proposed. First, the technique of target detection is applied to dynamic images (image sequences) to segment images into different targets and background regions. Then different fusion rules are employed in different regions so that the target information is preserved as much as possible. In addition, steerable non-separable wavelet frame transform is used in the process of multi-resolution analysis, so the system achieves favorable characters of orientation and invariant shift. Compared with other image fusion methods, experimental results showed that the proposed method has better capabilities of target recognition and preserves clear background information.

  7. [Analysis of spectral features based on water content of desert vegetation].

    Science.gov (United States)

    Zhao, Zhao; Li, Xia; Yin, Ye-biao; Tang, Jin; Zhou, Sheng-bin

    2010-09-01

    By using HR-768 field-portable spectroradiometer made by the Spectra Vista Corporation (SVC) of America, the hyper-spectral data of nine types of desert plants were measured, and the water content of corresponding vegetation was determined by roasting in lab. The continuum of measured hyperspectral data was removed by using ENVI, and the relationship between the water content of vegetation and the reflectance spectrum was analyzed by using correlation coefficient method. The result shows that the correlation between the bands from 978 to 1030 nm and water content of vegetation is weak while it is better for the bands from 1133 to 1266 nm. The bands from 1374 to 1534 nm are the characteristic bands because of the correlation between them and water content is the best. By using cluster analysis and according to the water content, the vegetation could be marked off into three grades: high (>70%), medium (50%-70%) and low (<50%). The research reveals the relationship between water content of desert vegetation and hyperspectral data, and provides basis for the analysis of area in desert and the monitoring of desert vegetation by using remote sensing data.

  8. Spectral and holographic characterization of new photochromic compounds based on substituted spiropyrans

    Science.gov (United States)

    Ciapurin, Igor V.; Robu, Stephan V.; Vlad, Lyudmila A.; Lessard, Roger A.; Tork, Amir; Lafond, Christophe; Bolte, Michel

    2001-06-01

    We report a new photochromic composite polymer consisting of poly-N-epoxypropylcarbazole (PEPC) polymeric matrix with a nitro-brome-substituted spiropyran (BNSP) photochromic dye. The PEPC + BNSP films can be considered as negative photochromic recording media. They are colored in the initial state and bleached upon irradiation within the visible spectra. When we placed the bleached samples to the darkness, they slowly revert to the colored form. This process has strong temperature dependence, so one can either 'freeze'' or accelerate changing of the current coloration state in the PEPC + BNSP. The experimental measurements are evaluated in conjunction with its potential applications for optical holographic recording in the visible spectral range. The real-time holographic recording procedure in PEPC + BNSP films was studied. The diffraction efficiency values reached the maximum of 23 percent at spatial frequency of 1600 line pairs per mm, during direct hologram recording with the 532 nm Coherent VERDI laser irradiation. Light exposures were ranged from 70 to 280 mJ/cm2. The investigated compounds have good perspectives for use in holography, two-photon optical data storage, electro-optics, and optical-limiting applications due to coupling of some unique properties such as high optical non-linearity, well charge transport, short response times, no-limiting resolution ability, etc.

  9. A Contribution for the Automatic Sleep Classification Based on the Itakura-Saito Spectral Distance

    Science.gov (United States)

    Cardoso, Eduardo; Batista, Arnaldo; Rodrigues, Rui; Ortigueira, Manuel; Bárbara, Cristina; Martinho, Cristina; Rato, Raul

    Sleep staging is a crucial step before the scoring the sleep apnoea, in subjects that are tested for this condition. These patients undergo a whole night polysomnography recording that includes EEG, EOG, ECG, EMG and respiratory signals. Sleep staging refers to the quantification of its depth. Despite the commercial sleep software being able to stage the sleep, there is a general lack of confidence amongst health practitioners of these machine results. Generally the sleep scoring is done over the visual inspection of the overnight patient EEG recording, which takes the attention of an expert medical practitioner over a couple of hours. This contributes to a waiting list of two years for patients of the Portuguese Health Service. In this work we have used a spectral comparison method called Itakura distance to be able to make a distinction between sleepy and awake epochs in a night EEG recording, therefore automatically doing the staging. We have used the data from 20 patients of Hospital Pulido Valente, which had been previously visually expert scored. Our technique results were promising, in a way that Itakura distance can, by itself, distinguish with a good degree of certainty the N2, N3 and awake states. Pre-processing stages for artefact reduction and baseline removal using Wavelets were applied.

  10. A Perceptual Model for Sinusoidal Audio Coding Based on Spectral Integration

    Directory of Open Access Journals (Sweden)

    Jensen Søren Holdt

    2005-01-01

    Full Text Available Psychoacoustical models have been used extensively within audio coding applications over the past decades. Recently, parametric coding techniques have been applied to general audio and this has created the need for a psychoacoustical model that is specifically suited for sinusoidal modelling of audio signals. In this paper, we present a new perceptual model that predicts masked thresholds for sinusoidal distortions. The model relies on signal detection theory and incorporates more recent insights about spectral and temporal integration in auditory masking. As a consequence, the model is able to predict the distortion detectability. In fact, the distortion detectability defines a (perceptually relevant norm on the underlying signal space which is beneficial for optimisation algorithms such as rate-distortion optimisation or linear predictive coding. We evaluate the merits of the model by combining it with a sinusoidal extraction method and compare the results with those obtained with the ISO MPEG-1 Layer I-II recommended model. Listening tests show a clear preference for the new model. More specifically, the model presented here leads to a reduction of more than 20% in terms of number of sinusoids needed to represent signals at a given quality level.

  11. Full waveform inversion based on the optimized gradient and its spectral implementation

    KAUST Repository

    Wu, Zedong

    2014-01-01

    Full waveform inversion (FWI) despite it\\'s potential suffers from the ability to converge to the desired solution due to the high nonlinearity of the objective function at conventional seismic frequencies. Even if frequencies necessary for the convergence are available, the high number of iterations required to approach a solution renders FWI as very expensive (especially in 3D). A spectral implementation in which the wavefields are extrapolated and gradients are calculated in the wavenumber domain allows for a cleaner more efficient implementation (no finite difference dispersion errors). In addition, we use not only an up and down going wavefield decomposition of the gradient to access the smooth background update, but also a right and left propagation decomposition to allow us to do that for large dips. To insure that the extracted smooth component of the gradient has the right decent direction, we solve an optimization problem to search for the smoothest component that provides a negative (decent) gradient. Application to the Marmousi model shows that this approach works well with linear increasing initial velocity model and data with frequencies above 2Hz.

  12. Real-time frequency-to-time mapping based on spectrally-discrete chromatic dispersion.

    Science.gov (United States)

    Dai, Yitang; Li, Jilong; Zhang, Ziping; Yin, Feifei; Li, Wangzhe; Xu, Kun

    2017-07-10

    Traditional photonics-assisted real-time Fourier transform (RTFT) usually suffers from limited chromatic dispersion, huge volume, or large time delay and attendant loss. In this paper we propose frequency-to-time mapping (FTM) by spectrally-discrete dispersion to increase frequency sensitivity greatly. The novel media has periodic ON/OFF intensity frequency response while quadratic phase distribution along disconnected channels, which de-chirps matched optical input to repeated Fourier-transform-limited output. Real-time FTM is then obtained within each period. Since only discrete phase retardation rather than continuously-changed true time delay is required, huge equivalent dispersion is then available by compact device. Such FTM is theoretically analyzed, and implementation by cascaded optical ring resonators is proposed. After a numerical example, our theory is demonstrated by a proof-of-concept experiment, where a single loop containing 0.5-meters-long fiber is used. FTM under 400-MHz unambiguous bandwidth and 25-MHz resolution is reported. Highly-sensitive and linear mapping is achieved with 6.25 ps/MHz, equivalent to ~4.6 × 10 4 -km standard single mode fiber. Extended instantaneous bandwidth is expected by ring cascading. Our proposal may provide a promising method for real-time, low-latency Fourier transform.

  13. Trust regions in Kriging-based optimization with expected improvement

    Science.gov (United States)

    Regis, Rommel G.

    2016-06-01

    The Kriging-based Efficient Global Optimization (EGO) method works well on many expensive black-box optimization problems. However, it does not seem to perform well on problems with steep and narrow global minimum basins and on high-dimensional problems. This article develops a new Kriging-based optimization method called TRIKE (Trust Region Implementation in Kriging-based optimization with Expected improvement) that implements a trust-region-like approach where each iterate is obtained by maximizing an Expected Improvement (EI) function within some trust region. This trust region is adjusted depending on the ratio of the actual improvement to the EI. This article also develops the Kriging-based CYCLONE (CYClic Local search in OptimizatioN using Expected improvement) method that uses a cyclic pattern to determine the search regions where the EI is maximized. TRIKE and CYCLONE are compared with EGO on 28 test problems with up to 32 dimensions and on a 36-dimensional groundwater bioremediation application in appendices supplied as an online supplement available at http://dx.doi.org/10.1080/0305215X.2015.1082350. The results show that both algorithms yield substantial improvements over EGO and they are competitive with a radial basis function method.

  14. Second Byurakan spectral sky survey. II. Results for region centered on alpha 09h50m, delta +55 deg 00 arcmin

    International Nuclear Information System (INIS)

    Markarian, B.E.; Stepanian, D.A.

    1984-01-01

    The second list of objects in the Second Biurakan Spectral Sky Survey of the region centered on alpha 09h50m, delta +55 deg 00 arcmin is given. The list contains data on 110 objects and galaxies of a peculiar physical nature and 24 blue stars. The observations were made with the 40-52 arcsec Schmidt telescope of the Biurakan Astrophysical Observatory with a set of three objective prisms using Kodak IIIaJ and IIIaF emulsions sensitized in nitrogen. The area is found to contain 20 quasar candidates and four Seyfert galaxies, 27 blue stellar objects, 24 galaxies with an appreciable ultraviolet continuum, and 39 emission galaxies without appreciable ultraviolet radiation. The surface brightness of the quasars and Seyferts on the considered area down to the limiting magnitude 19.5 M is more than 1.5 per square degree with allowance for the already known quasars. The surface density of emission galaxies is about four per square degree. 7 references

  15. Comparative study of the efficiency of computed univariate and multivariate methods for the estimation of the binary mixture of clotrimazole and dexamethasone using two different spectral regions

    Science.gov (United States)

    Fayez, Yasmin Mohammed; Tawakkol, Shereen Mostafa; Fahmy, Nesma Mahmoud; Lotfy, Hayam Mahmoud; Shehata, Mostafa Abdel-Aty

    2018-04-01

    Three methods of analysis are conducted that need computational procedures by the Matlab® software. The first is the univariate mean centering method which eliminates the interfering signal of the one component at a selected wave length leaving the amplitude measured to represent the component of interest only. The other two multivariate methods named PLS and PCR depend on a large number of variables that lead to extraction of the maximum amount of information required to determine the component of interest in the presence of the other. Good accurate and precise results are obtained from the three methods for determining clotrimazole in the linearity range 1-12 μg/mL and 75-550 μg/mL with dexamethasone acetate 2-20 μg/mL in synthetic mixtures and pharmaceutical formulation using two different spectral regions 205-240 nm and 233-278 nm. The results obtained are compared statistically to each other and to the official methods.

  16. Calculation of spectral shifts in UV–visible region and photoresponsive behaviour of fluorinated liquid crystals: Effect of solvent and substituent

    International Nuclear Information System (INIS)

    Lakshmi Praveen, P.; Ojha, Durga P.

    2012-01-01

    The photoresponsive behaviour of fluorinated liquid crystals p-phenylene-4-methoxy benzoate-4-trifluoromethylbenzoate (FLUORO1), and 4-propyloxyphenyl-4-(4-trifluoromethylbenzoyloxy) benzoate (FLUORO2) has been systematically investigated using the CNDO/S + CI and INDO/S + CI methods. These methods have been employed to calculate/analyze the spectral shifts, and absorbance measurements in UV–visible region of the systems. The electronic transitions, absorption wavelength, HOMO (highest occupied molecular orbital), and LUMO (lowest unoccupied molecular orbital) energies have been calculated. Further, ultraviolet (UV) stability of the molecules has been discussed in the light of absorption wavelength and electronic transition oscillator strength (f). The effect of different solvent media and substituents on transition energies, oscillator strength, and other absorption parameters have also been reported. The present article provides valuable information regarding enhancing the UV stability of molecules by marinating their conductivity. Highlights: ► The strongest bands of FLUORO molecules can be assigned as π → π ∗ transitions. ► A small red-shift indicates a weak exciton coupling of chromophores. ► No n → π ∗ transition occurs due to the rigidity of the ring system of the molecules. ► The HOMO, LUMO, and E g values have been found to be independent of solvent effect.

  17. Calculation of spectral shifts in UV-visible region and photoresponsive behaviour of fluorinated liquid crystals: Effect of solvent and substituent

    Energy Technology Data Exchange (ETDEWEB)

    Lakshmi Praveen, P. [Liquid Crystal Research Laboratory, Post-Graduate Department of Physics, Andhra Loyola College, Vijayawada 520 008, A.P. (India); Ojha, Durga P., E-mail: durga_ojha@hotmail.com [Liquid Crystal Research Laboratory, Post-Graduate Department of Physics, Andhra Loyola College, Vijayawada 520 008, A.P. (India)

    2012-08-15

    The photoresponsive behaviour of fluorinated liquid crystals p-phenylene-4-methoxy benzoate-4-trifluoromethylbenzoate (FLUORO1), and 4-propyloxyphenyl-4-(4-trifluoromethylbenzoyloxy) benzoate (FLUORO2) has been systematically investigated using the CNDO/S + CI and INDO/S + CI methods. These methods have been employed to calculate/analyze the spectral shifts, and absorbance measurements in UV-visible region of the systems. The electronic transitions, absorption wavelength, HOMO (highest occupied molecular orbital), and LUMO (lowest unoccupied molecular orbital) energies have been calculated. Further, ultraviolet (UV) stability of the molecules has been discussed in the light of absorption wavelength and electronic transition oscillator strength (f). The effect of different solvent media and substituents on transition energies, oscillator strength, and other absorption parameters have also been reported. The present article provides valuable information regarding enhancing the UV stability of molecules by marinating their conductivity. Highlights: Black-Right-Pointing-Pointer The strongest bands of FLUORO molecules can be assigned as {pi} {yields} {pi}{sup Asterisk-Operator} transitions. Black-Right-Pointing-Pointer A small red-shift indicates a weak exciton coupling of chromophores. Black-Right-Pointing-Pointer No n {yields} {pi}{sup Asterisk-Operator} transition occurs due to the rigidity of the ring system of the molecules. Black-Right-Pointing-Pointer The HOMO, LUMO, and E{sub g} values have been found to be independent of solvent effect.

  18. Proposal of a New Method for Neutron Dosimetry Based on Spectral Information Obtained by Application of Artificial Neural Networks

    International Nuclear Information System (INIS)

    Fehrenbacher, G.; Schuetz, R.; Hahn, K.; Sprunck, M.; Cordes, E.; Biersack, J.P.; Wahl, W.

    1999-01-01

    A new method for the monitoring of neutron radiation is proposed. It is based on the determination of spectral information on the neutron field in order to derive dose quantities like the ambient dose equivalent, the dose equivalent, or other dose quantities which depend on the neutron energy. The method uses a multi-element system consisting of converter type silicon detectors. The unfolding procedure is based on an artificial neural network (ANN). The response function of each element is determined by a computational model considering the neutron interaction with the dosemeter layers and the subsequent transport of produced ions. An example is given for a multi-element system. The ANN is trained by a given set of neutron spectra and then applied to count responses obtained in neutron fields. Four examples of spectra unfolded using the ANN are presented. (author)

  19. A postprocessing method based on high-resolution spectral estimation for FDTD calculation of phononic band structures

    Energy Technology Data Exchange (ETDEWEB)

    Su Xiaoxing, E-mail: xxsu@bjtu.edu.c [School of Electronic and Information Engineering, Beijing Jiaotong University, Beijing 100044 (China); Li Jianbao; Wang Yuesheng [Institute of Engineering Mechanics, Beijing Jiaotong University, Beijing 100044 (China)

    2010-05-15

    If the energy bands of a phononic crystal are calculated by the finite difference time domain (FDTD) method combined with the fast Fourier transform (FFT), good estimation of the eigenfrequencies can only be ensured by the postprocessing of sufficiently long time series generated by a large number of FDTD iterations. In this paper, a postprocessing method based on the high-resolution spectral estimation via the Yule-Walker method is proposed to overcome this difficulty. Numerical simulation results for three-dimensional acoustic and two-dimensional elastic systems show that, compared with the classic FFT-based postprocessing method, the proposed method can give much better estimation of the eigenfrequencies when the FDTD is run with relatively few iterations.

  20. A postprocessing method based on high-resolution spectral estimation for FDTD calculation of phononic band structures

    International Nuclear Information System (INIS)

    Su Xiaoxing; Li Jianbao; Wang Yuesheng

    2010-01-01

    If the energy bands of a phononic crystal are calculated by the finite difference time domain (FDTD) method combined with the fast Fourier transform (FFT), good estimation of the eigenfrequencies can only be ensured by the postprocessing of sufficiently long time series generated by a large number of FDTD iterations. In this paper, a postprocessing method based on the high-resolution spectral estimation via the Yule-Walker method is proposed to overcome this difficulty. Numerical simulation results for three-dimensional acoustic and two-dimensional elastic systems show that, compared with the classic FFT-based postprocessing method, the proposed method can give much better estimation of the eigenfrequencies when the FDTD is run with relatively few iterations.

  1. [The design and implementation of the web typical surface object spectral information system in arid areas based on .NET and SuperMap].

    Science.gov (United States)

    Xia, Jun; Tashpolat, Tiyip; Zhang, Fei; Ji, Hong-jiang

    2011-07-01

    The characteristic of object spectrum is not only the base of the quantification analysis of remote sensing, but also the main content of the basic research of remote sensing. The typical surface object spectral database in arid areas oasis is of great significance for applied research on remote sensing in soil salinization. In the present paper, the authors took the Ugan-Kuqa River Delta Oasis as an example, unified .NET and the SuperMap platform with SQL Server database stored data, used the B/S pattern and the C# language to design and develop the typical surface object spectral information system, and established the typical surface object spectral database according to the characteristics of arid areas oasis. The system implemented the classified storage and the management of typical surface object spectral information and the related attribute data of the study areas; this system also implemented visualized two-way query between the maps and attribute data, the drawings of the surface object spectral response curves and the processing of the derivative spectral data and its drawings. In addition, the system initially possessed a simple spectral data mining and analysis capabilities, and this advantage provided an efficient, reliable and convenient data management and application platform for the Ugan-Kuqa River Delta Oasis's follow-up study in soil salinization. Finally, It's easy to maintain, convinient for secondary development and practically operating in good condition.

  2. Cu{sub 1.5}Mn{sub 1.5}O{sub 4}-based ceramic spectrally selective coatings for efficient solar absorber applications

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Pengjun [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, 730000 (China); University of Chinese Academy of Sciences, Beijing, 100049 (China); Geng, Qingfen; Gao, Xianghu [Research & Development Center for Eco-material and Eco-chemistry, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, 730000 (China); Yang, Shengrong [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, 730000 (China); Liu, Gang, E-mail: gangliu@licp.cas.cn [Research & Development Center for Eco-material and Eco-chemistry, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, 730000 (China)

    2016-08-05

    Cu{sub 1.5}Mn{sub 1.5}O{sub 4}-based ceramic spectrally selective (CSS) coating was deposited on aluminum substrate using a sol–gel dip-coating method. The citric acid introduced in the precursor system lowered the required calcining temperature of crystalline Cu{sub 1.5}Mn{sub 1.5}O{sub 4}. X-Ray diffraction (XRD) peaks of coatings annealed above 450 °C were found to coincide exactly with that of crystalline Cu{sub 1.5}Mn{sub 1.5}O{sub 4} in JCPDS database. By optimizing the withdrawal rate and calcining temperature, coating with spectral selectivity as good as α{sub s} = 0.876 and ε{sub 100} = 0.057 was achieved after only one dipping/annealing cycle. Subjected to an accelerated ageing test at 259 °C, the obtained CSS coating showed an excellent thermally durability with the performance criterion (PC) values below 0.05. - Highlights: • Cu{sub 1.5}Mn{sub 1.5}O{sub 4}-based CSS coating is achieved after only one dipping/annealing cycle. • Cu{sub 1.5}Mn{sub 1.5}O{sub 4} coating is obtained as the annealing temperature reaches to 450 °C. • Cu{sub 1.5}Mn{sub 1.5}O{sub 4} coating exhibits optical parameter: α{sub s} = 0.876 and ε{sub 100} = 0.057. • Cu{sub 1.5}Mn{sub 1.5}O{sub 4} coating shows the excellent stability in low to mid temperature region.

  3. Defining a region of optimization based on engine usage data

    Science.gov (United States)

    Jiang, Li; Lee, Donghoon; Yilmaz, Hakan; Stefanopoulou, Anna

    2015-08-04

    Methods and systems for engine control optimization are provided. One or more operating conditions of a vehicle engine are detected. A value for each of a plurality of engine control parameters is determined based on the detected one or more operating conditions of the vehicle engine. A range of the most commonly detected operating conditions of the vehicle engine is identified and a region of optimization is defined based on the range of the most commonly detected operating conditions of the vehicle engine. The engine control optimization routine is initiated when the one or more operating conditions of the vehicle engine are within the defined region of optimization.

  4. Novel determination of the total phenolic content in crude plant extracts by the use of 1H NMR of the -OH spectral region

    International Nuclear Information System (INIS)

    Nerantzaki, A.A.; Tsiafoulis, C.G.; Charisiadis, P.; Kontogianni, V.G.; Gerothanassis, I.P.

    2011-01-01

    A novel method for the determination of the total phenolic content using 1 H NMR spectroscopy in the -OH spectral region is presented. The use of DMSO-d 6 , which is an aprotic and strongly hydrogen bonding solvent, allows the 'appearance' of the relative sharp resonances of phenolic hydroxyl protons in the region of 8-14 ppm. The determination of the total phenolic -OH content requires three steps: (i) a 1D 1 H NMR spectrum is obtained in DMSO-d 6 ; (ii) a subsequent 1D 1 H NMR spectrum is recorded with irradiation of the residual water signal which results in the elimination or reduction of the phenolic -OH groups, due to proton exchange; and (iii) 1D 1 H NMR spectra are recorded with the addition of a progressively increased amount of salt, NaHCO 3 , which results in extensive linebroadening of the COOH resonances thus allowing the discrimination of the phenolic from the carboxylic acid signals. Integration, with respect to the internal standard TSP-d 4 , of the signal resonances between 14 and 8 ppm in spectrum (i) which are either eliminated or reduced in intensity in steps (ii) and (iii) allows the quantitation of the total phenolic content. The method was applied to model compounds, a mixture of them and several extracts of natural products. The results of the proposed 1 H NMR method were compared to the Folin-Ciocalteu (FC) reagent method. Additionally, since 1 H NMR refers to the total phenolic hydroxyl protons, a reaction factor, A e , is proposed that corresponds to the hydroxyl reactivity. The 1 H NMR method is rapid and accurate bearing the inherent advantages of the NMR spectroscopy and can be applied directly in complex extracts. Furthermore, it can be applied in a wide range of matrixes from crude plant extracts and food products to biological samples.

  5. Fault feature extraction of planet gear in wind turbine gearbox based on spectral kurtosis and time wavelet energy spectrum

    Science.gov (United States)

    Kong, Yun; Wang, Tianyang; Li, Zheng; Chu, Fulei

    2017-09-01

    Planetary transmission plays a vital role in wind turbine drivetrains, and its fault diagnosis has been an important and challenging issue. Owing to the complicated and coupled vibration source, time-variant vibration transfer path, and heavy background noise masking effect, the vibration signal of planet gear in wind turbine gearboxes exhibits several unique characteristics: Complex frequency components, low signal-to-noise ratio, and weak fault feature. In this sense, the periodic impulsive components induced by a localized defect are hard to extract, and the fault detection of planet gear in wind turbines remains to be a challenging research work. Aiming to extract the fault feature of planet gear effectively, we propose a novel feature extraction method based on spectral kurtosis and time wavelet energy spectrum (SK-TWES) in the paper. Firstly, the spectral kurtosis (SK) and kurtogram of raw vibration signals are computed and exploited to select the optimal filtering parameter for the subsequent band-pass filtering. Then, the band-pass filtering is applied to extrude periodic transient impulses using the optimal frequency band in which the corresponding SK value is maximal. Finally, the time wavelet energy spectrum analysis is performed on the filtered signal, selecting Morlet wavelet as the mother wavelet which possesses a high similarity to the impulsive components. The experimental signals collected from the wind turbine gearbox test rig demonstrate that the proposed method is effective at the feature extraction and fault diagnosis for the planet gear with a localized defect.

  6. Bandwidth scalable, coherent transmitter based on the parallel synthesis of multiple spectral slices using optical arbitrary waveform generation.

    Science.gov (United States)

    Geisler, David J; Fontaine, Nicolas K; Scott, Ryan P; He, Tingting; Paraschis, Loukas; Gerstel, Ori; Heritage, Jonathan P; Yoo, S J B

    2011-04-25

    We demonstrate an optical transmitter based on dynamic optical arbitrary waveform generation (OAWG) which is capable of creating high-bandwidth (THz) data waveforms in any modulation format using the parallel synthesis of multiple coherent spectral slices. As an initial demonstration, the transmitter uses only 5.5 GHz of electrical bandwidth and two 10-GHz-wide spectral slices to create 100-ns duration, 20-GHz optical waveforms in various modulation formats including differential phase-shift keying (DPSK), quaternary phase-shift keying (QPSK), and eight phase-shift keying (8PSK) with only changes in software. The experimentally generated waveforms showed clear eye openings and separated constellation points when measured using a real-time digital coherent receiver. Bit-error-rate (BER) performance analysis resulted in a BER < 9.8 × 10(-6) for DPSK and QPSK waveforms. Additionally, we experimentally demonstrate three-slice, 4-ns long waveforms that highlight the bandwidth scalable nature of the optical transmitter. The various generated waveforms show that the key transmitter properties (i.e., packet length, modulation format, data rate, and modulation filter shape) are software definable, and that the optical transmitter is capable of acting as a flexible bandwidth transmitter.

  7. Unified picture of the photoexcitations in phenylene-based conjugated polymers: Universal spectral and dynamical features in subpicosecond transient absorption

    International Nuclear Information System (INIS)

    Kraabel, B.; Klimov, V. I.; Kohlman, R.; Xu, S.; Wang, H-L.; McBranch, D. W.

    2000-01-01

    Using subpicosecond transient absorption spectroscopy, we investigate the primary photoexcitations in thin films and solutions of several phenylene-based conjugated polymers and an oligomer. We identify several features in the transient absorption spectra and dynamics that are common to all of the materials which we studied from this family. The first spectral feature is a photoinduced absorption (PA) band peaking near 1 eV that has intensity-dependent dynamics that match the stimulated emission dynamics exactly over two orders of magnitude in excitation density. This band is associated with singlet intrachain excitons. The second spectral feature (observed only in thin films and aggregated solutions) is a PA band peaking near 1.8 eV, that is longer lived than the 1 eV exciton PA band, and that has dynamics that are independent (or weakly dependent) on excitation density. This feature is attributed to polarons, generated through a mechanism that is sample dependent. In pristine samples, polarons are generated via a mechanism that is quadratic in exciton density, whereas in photodegraded samples or samples doped with electron acceptors, the generation mechanism becomes linear in exciton density. (c) 2000 The American Physical Society

  8. Adaptive handling of Rayleigh and Raman scatter of fluorescence data based on evaluation of the degree of spectral overlap

    Science.gov (United States)

    Hu, Yingtian; Liu, Chao; Wang, Xiaoping; Zhao, Dongdong

    2018-06-01

    At present the general scatter handling methods are unsatisfactory when scatter and fluorescence seriously overlap in excitation emission matrix. In this study, an adaptive method for scatter handling of fluorescence data is proposed. Firstly, the Raman scatter was corrected by subtracting the baseline of deionized water which was collected in each experiment to adapt to the intensity fluctuations. Then, the degrees of spectral overlap between Rayleigh scatter and fluorescence were classified into three categories based on the distance between the spectral peaks. The corresponding algorithms, including setting to zero, fitting on single or both sides, were implemented after the evaluation of the degree of overlap for individual emission spectra. The proposed method minimized the number of fitting and interpolation processes, which reduced complexity, saved time, avoided overfitting, and most importantly assured the authenticity of data. Furthermore, the effectiveness of this procedure on the subsequent PARAFAC analysis was assessed and compared to Delaunay interpolation by conducting experiments with four typical organic chemicals and real water samples. Using this method, we conducted long-term monitoring of tap water and river water near a dyeing and printing plant. This method can be used for improving adaptability and accuracy in the scatter handling of fluorescence data.

  9. Spectral characteristics of 2-(4'-amino-3-pyridyl)benzimidazole: Effects of solvent and acid or base concentration

    International Nuclear Information System (INIS)

    Dogra, Sneh K.

    2006-01-01

    Spectral characteristics of 2-(4'-amino-3-pyridyl)benzimidazole (4-A3PyBI) have been studied in different solvents, as well as at different acid or base concentrations using absorption, fluorescence excitation and fluorescence spectroscopy. Excited singlet state (S 1 ) lifetimes for each species were measured using nanosecond time-dependent spectrofluorimeter. AM1 semi-empirical and density functional theoretical (DFT) calculations were performed on each species for the spectral assignment. From the above results it is concluded that 4-A3PyBI exists only in the amine form. First protonation occurs at pyridine=N- atom and second protonation at the benzimidazole (BI)=N- atom. When dication (DC) species is excited, two emission bands are observed, having the same fluorescence excitation spectra, suggesting the same ground state (S ) precursor. Short wavelength (SW) emission band is assigned to the π-π* transition and long wavelength (LW) emission to the charge transfer transition. First deprotonation in S state occurs from >N-H moiety, whereas in S 1 state it is from -NH 2 group. Monoanion (MA) so formed in S 1 state is non-fluorescent. Dianion (DA) is formed by further deprotonating >N-H moiety in S 1 state and it is fluorescent. pK a values were determined and discussed

  10. Region based Brain Computer Interface for a home control application.

    Science.gov (United States)

    Akman Aydin, Eda; Bay, Omer Faruk; Guler, Inan

    2015-08-01

    Environment control is one of the important challenges for disabled people who suffer from neuromuscular diseases. Brain Computer Interface (BCI) provides a communication channel between the human brain and the environment without requiring any muscular activation. The most important expectation for a home control application is high accuracy and reliable control. Region-based paradigm is a stimulus paradigm based on oddball principle and requires selection of a target at two levels. This paper presents an application of region based paradigm for a smart home control application for people with neuromuscular diseases. In this study, a region based stimulus interface containing 49 commands was designed. Five non-disabled subjects were attended to the experiments. Offline analysis results of the experiments yielded 95% accuracy for five flashes. This result showed that region based paradigm can be used to select commands of a smart home control application with high accuracy in the low number of repetitions successfully. Furthermore, a statistically significant difference was not observed between the level accuracies.

  11. Multiplex immunoassay for persistent organic pollutants in tilapia: comparison of imaging- and flow cytometry-based platforms using spectrally encoded paramagnetic microspheres

    NARCIS (Netherlands)

    Meimaridou, A.; Haasnoot, W.; Shelver, W.L.; Franek, M.; Nielen, M.W.F.

    2013-01-01

    Recent developments in spectrally encoded microspheres (SEMs)-based technologies provide high multiplexing possibilities. Most SEMs-based assays require a flow cytometer with sophisticated fluidics and optics. A new imaging super-paramagnetic SEMs-based alternative platform transports SEMs with

  12. Model-based automatic generation of grasping regions

    Science.gov (United States)

    Bloss, David A.

    1993-01-01

    The problem of automatically generating stable regions for a robotic end effector on a target object, given a model of the end effector and the object is discussed. In order to generate grasping regions, an initial valid grasp transformation from the end effector to the object is obtained based on form closure requirements, and appropriate rotational and translational symmetries are associated with that transformation in order to construct a valid, continuous grasping region. The main result of this algorithm is a list of specific, valid grasp transformations of the end effector to the target object, and the appropriate combinations of translational and rotational symmetries associated with each specific transformation in order to produce a continuous grasp region.

  13. Random Valued Impulse Noise Removal Using Region Based Detection Approach

    Directory of Open Access Journals (Sweden)

    S. Banerjee

    2017-12-01

    Full Text Available Removal of random valued noisy pixel is extremely challenging when the noise density is above 50%. The existing filters are generally not capable of eliminating such noise when density is above 70%. In this paper a region wise density based detection algorithm for random valued impulse noise has been proposed. On the basis of the intensity values, the pixels of a particular window are sorted and then stored into four regions. The higher density based region is considered for stepwise detection of noisy pixels. As a result of this detection scheme a maximum of 75% of noisy pixels can be detected. For this purpose this paper proposes a unique noise removal algorithm. It was experimentally proved that the proposed algorithm not only performs exceptionally when it comes to visual qualitative judgment of standard images but also this filter combination outsmarts the existing algorithm in terms of MSE, PSNR and SSIM comparison even up to 70% noise density level.

  14. A consumption-based, regional input-output analysis of greenhouse gas emissions and the carbon regional index

    DEFF Research Database (Denmark)

    Boyd, Britta; Mangalagiu, Diana; Straatman, Bas

    2018-01-01

    This paper presents a consumption-based method accounting for greenhouse gas emissions at regional level based on a multi-region input-output model. The method is based on regional consumption and includes imports and exports of emissions, factual emission developments, green investments as well...

  15. Quantum-mechanical vs. semi-classical spectral-line widths and shifts from the line core in the non-impact region for the Ar-perturbed/ K-radiator system

    International Nuclear Information System (INIS)

    Kreye, W.C.

    2007-01-01

    New quantum-mechanical (QM) and semi-classical (SC) shifts (d's) and widths (HWHM's, w's) were measured from the line core of computed full spectral-line shapes for the Ar-perturbed/K-radiator system (K/Ar). The initial state of our model was based on a 4p 2 P 3/2,1/2 pseudo-potential for the K/Ar system, and the final state on a zero potential. The Fourier transform of the line shape formed the basis for the computations. Excellent agreement was found between the QM and SC values of d and of w in a high-pressure (P) non-impact region, which was characterized by a √P dependence of w and a P dependence of d. These agreements were shown to be another example of a correspondence between classical (SC) quantities and QM quantities in the limit of large quantum numbers. Typically at P=1x10 6 Torr and T=400 K, w QM =448 cm -1 and w SC =479 cm -1 , where the deviation from the mean is ±3.3%. Also, d QM =-3815 cm -1 and d SC =-3716 cm -1 , where the deviation from the mean is ±1.3%. A new general method was formulated which yielded a definite pressure P 0 , which was defined as an upper limit to the low-pressure impact approximation and a lower limit to the non-impact region

  16. Knowledge base combinations and innovation performance in Swedish regions

    Czech Academy of Sciences Publication Activity Database

    Grillitsch, M.; Martin, R.; Srholec, Martin

    2017-01-01

    Roč. 93, č. 5 (2017), s. 458-479 ISSN 0013-0095 Institutional support: Progres-Q24 Keywords : knowledge base * knowledge combination * region Subject RIV: AH - Economics OBOR OECD: Applied Economics, Econometrics Impact factor: 5.344, year: 2016

  17. Knowledge base combinations and innovation performance in Swedish regions

    Czech Academy of Sciences Publication Activity Database

    Grillitsch, M.; Martin, R.; Srholec, Martin

    2017-01-01

    Roč. 93, č. 5 (2017), s. 458-479 ISSN 0013-0095 Institutional support: RVO:67985998 Keywords : knowledge base * knowledge combination * region Subject RIV: AH - Economics OBOR OECD: Applied Economics, Econometrics Impact factor: 5.344, year: 2016

  18. Ultra-Widefield Steering-Based Spectral-Domain Optical Coherence Tomography Imaging of the Retinal Periphery.

    Science.gov (United States)

    Choudhry, Netan; Golding, John; Manry, Matthew W; Rao, Rajesh C

    2016-06-01

    To describe the spectral-domain optical coherence tomography (SD OCT) features of peripheral retinal findings using an ultra-widefield (UWF) steering technique to image the retinal periphery. Observational study. A total of 68 patients (68 eyes) with 19 peripheral retinal features. Spectral-domain OCT-based structural features. Nineteen peripheral retinal features, including vortex vein, congenital hypertrophy of the retinal pigment epithelium, pars plana, ora serrata pearl, typical cystoid degeneration (TCD), cystic retinal tuft, meridional fold, lattice and cobblestone degeneration, retinal hole, retinal tear, rhegmatogenous retinal detachment, typical degenerative senile retinoschisis, peripheral laser coagulation scars, ora tooth, cryopexy scars (retinal tear and treated retinoblastoma scar), bone spicules, white without pressure, and peripheral drusen, were identified by peripheral clinical examination. Near-infrared scanning laser ophthalmoscopy images and SD OCT of these entities were registered to UWF color photographs. Spectral-domain OCT resolved structural features of all peripheral findings. Dilated hyporeflective tubular structures within the choroid were observed in the vortex vein. Loss of retinal lamination, neural retinal attenuation, retinal pigment epithelium loss, or hypertrophy was seen in several entities, including congenital hypertrophy of the retinal pigment epithelium, ora serrata pearl, TCD, cystic retinal tuft, meridional fold, lattice, and cobblestone degenerations. Hyporeflective intraretinal spaces, indicating cystoid or schitic fluid, were seen in ora serrata pearl, ora tooth, TCD, cystic retinal tuft, meridional fold, retinal hole, and typical degenerative senile retinoschisis. The vitreoretinal interface, which often consisted of lamellae-like structures of the condensed cortical vitreous near or adherent to the neural retina, appeared clearly in most peripheral findings, confirming its association with many low-risk and vision

  19. Tropospheric nitrogen dioxide inversions based on spectral measurements of scattered sunlight

    NARCIS (Netherlands)

    Vlemmix, T.

    2011-01-01

    This thesis describes the development of inversion methods for tropospheric nitrogen dioxide (NO2), based on ground based observations of scattered sunlight with themulti-axis differential optical absorption spectroscopy (MAX-DOAS) technique. NO2 is an atmospheric trace gas which, when present near

  20. Near-diffraction-limited segmented broad area diode laser based on off-axis spectral beam combining

    DEFF Research Database (Denmark)

    Jensen, O.B.; Thestrup Nielsen, Birgitte; Andersen, Peter E.

    2006-01-01

    -feedback scheme we are able to improve the beam quality of the laser by a factor of 23 from M-2 = 55 for the free-running diode laser to M-2 = 2.4 for the laser with feedback at a drive current of 2.2 A. The improved M-2 value is a factor of 3.4 below M-2 = 8.2 for a single free-running segment. This is the first......The beam quality of a 500-mu m-wide broad area diode laser with five active segments has been improved beyond the beam quality of the individual segments. The principle of this new laser system is based on off-axis feedback in combination with spectral beam combining. By using a double...... time that the beam quality of a segmented broad area diode laser has been improved beyond the beam quality of the individual segments....

  1. Spectral, Electrochemical, Fluorescence, Kinetic and Anti-microbial Studies of Acyclic Schiff-base Gadolinium(III) Complexes

    International Nuclear Information System (INIS)

    Vijayaraj, A.; Prabu, R.; Suresh, R.; Narayanan, V.; Sangeetha Kumari, R.; Kaviyarasan, V.

    2012-01-01

    A new series of acyclic mononuclear gadolinium(III) complexes have been prepared by Schiff-base condensation derived from 5-methylsalicylaldehyde, diethylenetriamine, tris(2-aminoethyl) amine, triethylenetetramine, N,N-bis(3-aminopropyl)ethylene diamine, N,N-bis(aminopropyl) piperazine, and gadolinium nitrate. All the complexes were characterized by elemental and spectral analyses. Electronic spectra of the complexes show azomethine (CH=N) within the range of 410-420 nm. The fluorescence efficiency of Gd(III) ion in the cavity was completely quenched by the higher chain length ligands. Electrochemical studies of the complexes show irreversible one electron reduction process around -2.15 to -1.60 V. The reduction potential of gadolinium(III) complexes shifts towards anodic directions respectively upon increasing the chain length. The catalytic activity of the gadolinium(III) complexes on the hydrolysis of 4-nitrophenylphosphate was determined. All gadolinium(III) complexes were screened for antibacterial activity

  2. Spectral, Electrochemical, Fluorescence, Kinetic and Anti-microbial Studies of Acyclic Schiff-base Gadolinium(III) Complexes

    Energy Technology Data Exchange (ETDEWEB)

    Vijayaraj, A.; Prabu, R.; Suresh, R.; Narayanan, V.; Sangeetha Kumari, R.; Kaviyarasan, V. [Univ. of Madras, Madras (India)

    2012-11-15

    A new series of acyclic mononuclear gadolinium(III) complexes have been prepared by Schiff-base condensation derived from 5-methylsalicylaldehyde, diethylenetriamine, tris(2-aminoethyl) amine, triethylenetetramine, N,N-bis(3-aminopropyl)ethylene diamine, N,N-bis(aminopropyl) piperazine, and gadolinium nitrate. All the complexes were characterized by elemental and spectral analyses. Electronic spectra of the complexes show azomethine (CH=N) within the range of 410-420 nm. The fluorescence efficiency of Gd(III) ion in the cavity was completely quenched by the higher chain length ligands. Electrochemical studies of the complexes show irreversible one electron reduction process around -2.15 to -1.60 V. The reduction potential of gadolinium(III) complexes shifts towards anodic directions respectively upon increasing the chain length. The catalytic activity of the gadolinium(III) complexes on the hydrolysis of 4-nitrophenylphosphate was determined. All gadolinium(III) complexes were screened for antibacterial activity.

  3. Impacts of spectral nudging on the simulated surface air temperature in summer compared with the selection of shortwave radiation and land surface model physics parameterization in a high-resolution regional atmospheric model

    Science.gov (United States)

    Park, Jun; Hwang, Seung-On

    2017-11-01

    The impact of a spectral nudging technique for the dynamical downscaling of the summer surface air temperature in a high-resolution regional atmospheric model is assessed. The performance of this technique is measured by comparing 16 analysis-driven simulation sets of physical parameterization combinations of two shortwave radiation and four land surface model schemes of the model, which are known to be crucial for the simulation of the surface air temperature. It is found that the application of spectral nudging to the outermost domain has a greater impact on the regional climate than any combination of shortwave radiation and land surface model physics schemes. The optimal choice of two model physics parameterizations is helpful for obtaining more realistic spatiotemporal distributions of land surface variables such as the surface air temperature, precipitation, and surface fluxes. However, employing spectral nudging adds more value to the results; the improvement is greater than using sophisticated shortwave radiation and land surface model physical parameterizations. This result indicates that spectral nudging applied to the outermost domain provides a more accurate lateral boundary condition to the innermost domain when forced by analysis data by securing the consistency with large-scale forcing over a regional domain. This consequently indirectly helps two physical parameterizations to produce small-scale features closer to the observed values, leading to a better representation of the surface air temperature in a high-resolution downscaled climate.

  4. A Region-Based Strategy for Collaborative Roadmap Construction

    KAUST Repository

    Denny, Jory; Sandströ m, Read; Julian, Nicole; Amato, Nancy M.

    2015-01-01

    © Springer International Publishing Switzerland 2015. Motion planning has seen much attention over the past two decades. A great deal of progress has been made in sampling-based planning, whereby a planner builds an approximate representation of the planning space. While these planners have demonstrated success inmany scenarios, there are still difficult problems where they lack robustness or efficiency, e.g., certain types of narrow spaces. Conversely, human intuition can often determine an approximate solution to these problems quite effectively, but humans lack the speed and precision necessary to perform the corresponding low-level tasks (such as collision checking) in a timely manner. In this work, we introduce a novel strategy called Region Steering in which the user and a PRM planner work cooperatively to map the space while maintaining the probabilistic completeness property of the PRMplanner. Region Steering utilizes two-way communication to integrate the strengths of both the user and the planner, thereby overcoming the weaknesses inherent to relying on either one alone. In one communication direction, a user can input regions, or bounding volumes in the workspace, to bias sampling towards or away from these areas. In the other direction, the planner displays its progress to the user and colors the regions based on their perceived usefulness.We demonstrate that Region Steering provides roadmap customizability, reduced mapping time, and smaller roadmap sizes compared with fully automated PRMs, e.g., Gaussian PRM.

  5. Morphological study of maxillary canine region based on CT

    International Nuclear Information System (INIS)

    Yamada, Maiko; Takamori, Hitoshi; Ide, Yoshiaki; Yosue, Takashi

    2010-01-01

    The maxilla is generally known as a site where anatomical limitations make it difficult to obtain sufficient bone volume. A large amount of bone exists in the canine region between the anterior margin of the maxillary sinus and the piriform aperture margin. Although this region is crucial for implant treatments, there have not been any reports on morphological studies of the region. In this study, we investigated the morphology of the canine region based on CT, and also the morphology and position of the maxillary sinus located posterior to the canine region. The results were as follows: In the area above the anterior nasal spine, the higher the level, the smaller the mesio-distal length and the bucco-lingual width tended to become. In the area above the anterior nasal spine, the mesio-distal length and the bucco-lingual width tended to be smaller in female patients than in male patients. In the area above the anterior nasal spine, no significant differences in mesio-distal length and bucco-lingual width were observed between dentulous and edentulous jaws. The morphology of the maxillary sinus was mainly of an inverse-trapezoidal, circular, or triangular form. The position of the anterior wall of the maxillary sinus was most frequently found at the site corresponding to the second premolar. Through this study, we have reconfirmed that the canine region is vital for implant treatments in the maxilla. (author)

  6. Optimisation of a polygon mirror-based spectral filter for swept source optical coherence tomography (SS-OCT)

    Science.gov (United States)

    Everson, Michael; Duma, Virgil-Florin; Dobre, George

    2018-03-01

    Medical imaging using Optical Coherence Tomography (OCT) provides clinicians with 3D, high resolution reconstructions of microscopic structures, in depth. It has been initially developed for ophthalmology, in order to scan the retinas of patients to diagnose illness. The quality of the images depends upon their axial and lateral resolutions and the properties of the light being used. Research using a polygon mirror (PM) as a spectral filter in Swept Source OCT (SS-OCT) has resulted in a variety of different experimental arrangements. Although the application of PM-based SS-OCT sources has been successfully demonstrated, the combination of their components' fundamental properties and the overall impact they have on imaging performance is rarely reported. A more detailed examination of these properties would lead to a full description of their operation and to the best methods to employ if system performance is to be maximised. This work presents our current findings of on-going research into the optimisation of PM-based SS-OCT systems. A swept source spectral filter, consisting of a collimator, a transmission grating, a two-lens telescope and an off-axis PM with an end reflector mirror has been evaluated experimentally and compared with theoretical predictions. The system's performance has been compared for two different fibre collimators. Although the beam width on the grating is different for each of the two collimators, the spot size at the PM facet is made the same by selecting appropriate focal lengths. An improvement in the signal roll-off at the interferometer output of 1.0 dB/mm was obtained when using a 3.4 mm collimator compared to a 1.5 mm collimator.

  7. Spectral Slope as an Indicator of Pasture Quality

    Directory of Open Access Journals (Sweden)

    Rachel Lugassi

    2014-12-01

    Full Text Available In this study, we develop a spectral method for assessment of pasture quality based only on the spectral information obtained with a small number of wavelengths. First, differences in spectral behavior were identified across the near infrared–shortwave infrared spectral range that were indicative of changes in chemical properties. Then, slopes across different spectral ranges were calculated and correlated with the changes in crude protein (CP, neutral detergent fiber (NDF and metabolic energy concentration (MEC. Finally, partial least squares (PLS regression analysis was applied to identify the optimal spectral ranges for accurate assessment of CP, NDF and MEC. Six spectral domains and a set of slope criteria for real-time evaluation of pasture quality were suggested. The evaluation of three level categories (low, medium, high for these three parameters showed a success rate of: 73%–96% for CP, 72%–87% for NDF and 60%–85% for MEC. Moreover, only one spectral range, 1748–1764 nm, was needed to provide a good estimation of CP, NDF and MEC. Importantly, five of the six selected spectral regions were not affected by water absorbance. With some modifications, this rationale can be applied to further analyses of pasture quality from airborne sensors.

  8. Electropharmacogram of Sceletium tortuosum extract based on spectral local field power in conscious freely moving rats.

    Science.gov (United States)

    Dimpfel, Wilfried; Schombert, Leonie; Gericke, Nigel

    2016-01-11

    The endemic succulent South African plant, Sceletium tortuosum (L.) N.E. Br. (synonym Mesembryanthemum tortuosum L.), of the family Mesembryathemaceae, has an ancient oral tradition history of use by San and Khoikhoi people as an integral part of the indigenous culture and materia medica. A special standardized extract of Sceletium tortuosum (Zembrin®) has been developed and tested pre-clinically in rats, and clinically in healthy subjects. The present investigation aimed at the construction of electropharmacograms of Zembrin® in the presence of three dosages (2.5, 5.0 and 10.0 mg/kg), and comparative electropharmacograms and discriminatory analyses for other herbal extracts, citicoline and rolipram. Seventeen adult Fischer rats were each implanted with a set consisting of four bipolar concentric steel electrodes fixed by dental cement and three screws driven into the scalp. After two weeks of recovery from surgery the animals were adapted to oral administration by gavage and to experimental conditions (45 min pre-drug period and 5h of recording after a rest of 5 min for calming down). Data were transmitted wirelessly and processed using a Fast Fourier Transformation (FFT). Spectral power was evaluated for 8 frequency ranges, namely delta, theta, alpha1, alpha2, beta1a, beta1b, beta2 and gamma power. Zembrin® dose dependently attenuated all frequency ranges, to varying degrees. The most prominent was the statistically significant reduction in alpha2 and beta1a waves, correlated with activation of the dopaminergic and glutamatergic transmitter systems respectively. This feature is common to all synthetic and herbal stimulants tested to date. The second strongest effects were reduction in both the delta and the theta frequency ranges, correlated with changes in the cholinergic and norepinephrine systems respectively, a pattern seen in preparations prescribed for neurodegenerative diseases. Theta wave reduction in common with the delta, alpha2 and beta1 attenuation

  9. [Analysis of software for identifying spectral line of laser-induced breakdown spectroscopy based on LabVIEW].

    Science.gov (United States)

    Hu, Zhi-yu; Zhang, Lei; Ma, Wei-guang; Yan, Xiao-juan; Li, Zhi-xin; Zhang, Yong-zhi; Wang, Le; Dong, Lei; Yin, Wang-bao; Jia, Suo-tang

    2012-03-01

    Self-designed identifying software for LIBS spectral line was introduced. Being integrated with LabVIEW, the soft ware can smooth spectral lines and pick peaks. The second difference and threshold methods were employed. Characteristic spectrum of several elements matches the NIST database, and realizes automatic spectral line identification and qualitative analysis of the basic composition of sample. This software can analyze spectrum handily and rapidly. It will be a useful tool for LIBS.

  10. Regional markets with agricultural workforce based on Labour offices' data

    Directory of Open Access Journals (Sweden)

    František Nohel

    2011-01-01

    Full Text Available The changes in Czech agriculture over the past twenty years have had their impact on the agricultural labour market, too. The regional differentiation of the chances of applicants on the labour market as well as the agricultural enterprises’ chances of hiring employees fitting their requirements, are, among others, influenced by the specific conditions of agricultural production. The aim of this paper pertains to two basic problem areas: first, the differentiation of respective regions based on the number of agricultural applicants and job vacancies, and second, the identification of disequilibrium on the agricultural labour market. The latter is based on a theoretical framework defined by approaches in economy dealing with labour market equilibrium. Due to the unavailability of economic data (including wages, economic performance, etc. on the regional level, authors develop their own methodological approach, based on the number of applicants per job vacancy. A database of applicants and vacancies available from the Labour Offices is used as a source for the analysis and interpretation of data, enabling us to study the agricultural labour market not only sector-wise but also region-wise.

  11. GNSS-based Observations and Simulations of Spectral Scintillation Indices in the Arctic Ionosphere

    DEFF Research Database (Denmark)

    Durgonics, Tibor; Hoeg, Per; von Benzon, Hans-Henrik

    During disturbed times, ionospheric scintillations can be severe and adversely impact satellite-based positioning and radio transmissions. The scintillation occurs in the amplitude, phase, polarization, and angle of arrival of the signal. Precise observation, classification, modeling, forecasting...

  12. Spectral backward radiation profile

    International Nuclear Information System (INIS)

    Kwon, Sung Duck; Lee, Keun Hyun; Kim, Bo Ra; Yoon, Suk Soo

    2004-01-01

    Ultrasonic backward radiation profile is frequency-dependent when incident region has deptional gradient of acoustical properties or multi-layers. Until now, we have measured the profiles of principal frequencies of used transducers so that it was not easy to understand the change of the frequency component and spectrum of backward radiation from the profile. We tried to measure the spectral backward radiation profiles using DFP(digital filer package) Lecroy DSO. The very big changes in the shape and pattern of spectral backward radiation profiles leads to the conclusion that this new try could be very effective tool to evaluate frequency dependent surface area.

  13. Optically pumped quantum-dot Cd(Zn)Se/ZnSe laser and microchip converter for yellow-green spectral region

    Energy Technology Data Exchange (ETDEWEB)

    Lutsenko, E V; Voinilovich, A G; Rzheutskii, N V; Pavlovskii, V N; Yablonskii, G P; Sorokin, S V; Gronin, S V; Sedova, I V; Kop' ev, Petr S; Ivanov, Sergei V; Alanzi, M; Hamidalddin, A; Alyamani, A

    2013-05-31

    The room temperature laser generation in the yellow-green ({lambda} = 558.5-566.7 nm) spectral range has been demonstrated under optical pumping by a pulsed nitrogen laser of Cd(Zn)Se/ZnSe quantum dot heterostructures. The maximum achieved laser wavelength was as high as {lambda} = 566.7 nm at a laser cavity length of 945 {mu}m. High values of both the output pulsed power (up to 50 W) and the external differential quantum efficiency ({approx}60%) were obtained at a cavity length of 435 {mu}m. Both a high quality of the laser heterostructure and a low lasing threshold ({approx}2 kW cm{sup -2}) make it possible to use a pulsed InGaN laser diode as a pump source. A laser microchip converter based on this heterostructure has demonstrated a maximum output pulse power of {approx}90 mW at {lambda} = 560 nm. The microchip converter was placed in a standard TO-18 (5.6 mm in diameter) laser diode package. (semiconductor lasers. physics and technology)

  14. Long ranging swept-source optical coherence tomography-based angiography outperforms its spectral-domain counterpart in imaging human skin microcirculations

    Science.gov (United States)

    Xu, Jingjiang; Song, Shaozhen; Men, Shaojie; Wang, Ruikang K.

    2017-11-01

    There is an increasing demand for imaging tools in clinical dermatology that can perform in vivo wide-field morphological and functional examination from surface to deep tissue regions at various skin sites of the human body. The conventional spectral-domain optical coherence tomography-based angiography (SD-OCTA) system is difficult to meet these requirements due to its fundamental limitations of the sensitivity roll-off, imaging range as well as imaging speed. To mitigate these issues, we demonstrate a swept-source OCTA (SS-OCTA) system by employing a swept source based on a vertical cavity surface-emitting laser. A series of comparisons between SS-OCTA and SD-OCTA are conducted. Benefiting from the high system sensitivity, long imaging range, and superior roll-off performance, the SS-OCTA system is demonstrated with better performance in imaging human skin than the SD-OCTA system. We show that the SS-OCTA permits remarkable deep visualization of both structure and vasculature (up to ˜2 mm penetration) with wide field of view capability (up to 18×18 mm2), enabling a more comprehensive assessment of the morphological features as well as functional blood vessel networks from the superficial epidermal to deep dermal layers. It is expected that the advantages of the SS-OCTA system will provide a ground for clinical translation, benefiting the existing dermatological practice.

  15. Ship motion-based wave estimation using a spectral residual-calculation

    DEFF Research Database (Denmark)

    Nielsen, Ulrik D.; H. Brodtkorb, Astrid

    2018-01-01

    This paper presents a study focused on a newly developed procedure for wave spectrum estimation using wave-induced motion recordings from a ship. The particular procedure stands out from other existing, similar ship motion-based pro-cedures by its computational efficiency and - at the same time- ...

  16. Synthesis and spectral studies of some novel coumarin based disperse azo dyes

    International Nuclear Information System (INIS)

    Amjad, R.; Khan, S.R.; Naeem, M.

    2009-01-01

    Synthesis of some novel coumarin based azo dyes was carried out by diazotization of heterocyclic amines using nitrosyl sulphuric acid and then coupling them with 7-hydroxy-4-methyl Coumarin. The synthesized dyes when applied on polyester fibers showed moderate to good light fastness and very good to excellent fastness to washing, rubbing, perspiration and sublimation. (author)

  17. Validation of the spectral mismatch correction factor using an LED-based solar simulator

    DEFF Research Database (Denmark)

    Riedel, Nicholas; Santamaria Lancia, Adrian Alejo; Thorsteinsson, Sune

    LED-based solar simulators are gaining popularity in the PV characterization field. There are several reasons for this trend, but the primary interest is often the potential of tuning the light source spectrum to a closer match to the AM 1.5G reference spectrum than traditional Xenon or metal-hal...

  18. PROSPECTS OF THE REGIONAL INTEGRATION POLICY BASED ON CLUSTER FORMATION

    Directory of Open Access Journals (Sweden)

    Elena Tsepilova

    2018-01-01

    Full Text Available The purpose of this article is to develop the theoretical foundations of regional integration policy and to determine its prospects on the basis of cluster formation. The authors use such research methods as systematization, comparative and complex analysis, synthesis, statistical method. Within the framework of the research, the concept of regional integration policy is specified, and its integration core – cluster – is allocated. The authors work out an algorithm of regional clustering, which will ensure the growth of economy and tax income. Measures have been proposed to optimize the organizational mechanism of interaction between the participants of the territorial cluster and the authorities that allow to ensure the effective functioning of clusters, including taxation clusters. Based on the results of studying the existing methods for assessing the effectiveness of cluster policy, the authors propose their own approach to evaluating the consequences of implementing the regional integration policy, according to which the list of quantitative and qualitative indicators is defined. The present article systematizes the experience and results of the cluster policy of certain European countries, that made it possible to determine the prospects and synergetic effect from the development of clusters as an integration foundation of regional policy in the Russian Federation. The authors carry out the analysis of activity of cluster formations using the example of the Rostov region – a leader in the formation of conditions for the cluster policy development in the Southern Federal District. 11 clusters and cluster initiatives are developing in this region. As a result, the authors propose measures for support of the already existing clusters and creation of the new ones.

  19. Estimation for sparse vegetation information in desertification region based on Tiangong-1 hyperspectral image.

    Science.gov (United States)

    Wu, Jun-Jun; Gao, Zhi-Hai; Li, Zeng-Yuan; Wang, Hong-Yan; Pang, Yong; Sun, Bin; Li, Chang-Long; Li, Xu-Zhi; Zhang, Jiu-Xing

    2014-03-01

    In order to estimate the sparse vegetation information accurately in desertification region, taking southeast of Sunite Right Banner, Inner Mongolia, as the test site and Tiangong-1 hyperspectral image as the main data, sparse vegetation coverage and biomass were retrieved based on normalized difference vegetation index (NDVI) and soil adjusted vegetation index (SAVI), combined with the field investigation data. Then the advantages and disadvantages between them were compared. Firstly, the correlation between vegetation indexes and vegetation coverage under different bands combination was analyzed, as well as the biomass. Secondly, the best bands combination was determined when the maximum correlation coefficient turned up between vegetation indexes (VI) and vegetation parameters. It showed that the maximum correlation coefficient between vegetation parameters and NDVI could reach as high as 0.7, while that of SAVI could nearly reach 0.8. The center wavelength of red band in the best bands combination for NDVI was 630nm, and that of the near infrared (NIR) band was 910 nm. Whereas, when the center wavelength was 620 and 920 nm respectively, they were the best combination for SAVI. Finally, the linear regression models were established to retrieve vegetation coverage and biomass based on Tiangong-1 VIs. R2 of all models was more than 0.5, while that of the model based on SAVI was higher than that based on NDVI, especially, the R2 of vegetation coverage retrieve model based on SAVI was as high as 0.59. By intersection validation, the standard errors RMSE based on SAVI models were lower than that of the model based on NDVI. The results showed that the abundant spectral information of Tiangong-1 hyperspectral image can reflect the actual vegetaion condition effectively, and SAVI can estimate the sparse vegetation information more accurately than NDVI in desertification region.

  20. Region-Based Building Rooftop Extraction and Change Detection

    Science.gov (United States)

    Tian, J.; Metzlaff, L.; d'Angelo, P.; Reinartz, P.

    2017-09-01

    Automatic extraction of building changes is important for many applications like disaster monitoring and city planning. Although a lot of research work is available based on 2D as well as 3D data, an improvement in accuracy and efficiency is still needed. The introducing of digital surface models (DSMs) to building change detection has strongly improved the resulting accuracy. In this paper, a post-classification approach is proposed for building change detection using satellite stereo imagery. Firstly, DSMs are generated from satellite stereo imagery and further refined by using a segmentation result obtained from the Sobel gradients of the panchromatic image. Besides the refined DSMs, the panchromatic image and the pansharpened multispectral image are used as input features for mean-shift segmentation. The DSM is used to calculate the nDSM, out of which the initial building candidate regions are extracted. The candidate mask is further refined by morphological filtering and by excluding shadow regions. Following this, all segments that overlap with a building candidate region are determined. A building oriented segments merging procedure is introduced to generate a final building rooftop mask. As the last step, object based change detection is performed by directly comparing the building rooftops extracted from the pre- and after-event imagery and by fusing the change indicators with the roof-top region map. A quantitative and qualitative assessment of the proposed approach is provided by using WorldView-2 satellite data from Istanbul, Turkey.

  1. REGION-BASED BUILDING ROOFTOP EXTRACTION AND CHANGE DETECTION

    Directory of Open Access Journals (Sweden)

    J. Tian

    2017-09-01

    Full Text Available Automatic extraction of building changes is important for many applications like disaster monitoring and city planning. Although a lot of research work is available based on 2D as well as 3D data, an improvement in accuracy and efficiency is still needed. The introducing of digital surface models (DSMs to building change detection has strongly improved the resulting accuracy. In this paper, a post-classification approach is proposed for building change detection using satellite stereo imagery. Firstly, DSMs are generated from satellite stereo imagery and further refined by using a segmentation result obtained from the Sobel gradients of the panchromatic image. Besides the refined DSMs, the panchromatic image and the pansharpened multispectral image are used as input features for mean-shift segmentation. The DSM is used to calculate the nDSM, out of which the initial building candidate regions are extracted. The candidate mask is further refined by morphological filtering and by excluding shadow regions. Following this, all segments that overlap with a building candidate region are determined. A building oriented segments merging procedure is introduced to generate a final building rooftop mask. As the last step, object based change detection is performed by directly comparing the building rooftops extracted from the pre- and after-event imagery and by fusing the change indicators with the roof-top region map. A quantitative and qualitative assessment of the proposed approach is provided by using WorldView-2 satellite data from Istanbul, Turkey.

  2. Magnetic Field Sensing Based on Bi-Tapered Optical Fibers Using Spectral Phase Analysis.

    Science.gov (United States)

    Herrera-Piad, Luis A; Haus, Joseph W; Jauregui-Vazquez, Daniel; Sierra-Hernandez, Juan M; Estudillo-Ayala, Julian M; Lopez-Dieguez, Yanelis; Rojas-Laguna, Roberto

    2017-10-20

    A compact, magnetic field sensor system based on a short, bi-tapered optical fiber (BTOF) span lying on a magnetic tape was designed, fabricated, and characterized. We monitored the transmission spectrum from a broadband light source, which displayed a strong interference signal. After data collection, we applied a phase analysis of the interference optical spectrum. We here report the results on two fabricated, BTOFs with different interference spectrum characteristics; we analyzed the signal based on the interference between a high-order modal component and the core fiber mode. The sensor exhibited a linear response for magnetic field increments, and we achieved a phase sensitivity of around 0.28 rad/mT. The sensing setup presented remote sensing operation and low-cost transducer magnetic material.

  3. Magnetic Field Sensing Based on Bi-Tapered Optical Fibers Using Spectral Phase Analysis

    Directory of Open Access Journals (Sweden)

    Luis A. Herrera-Piad

    2017-10-01

    Full Text Available A compact, magnetic field sensor system based on a short, bi-tapered optical fiber (BTOF span lying on a magnetic tape was designed, fabricated, and characterized. We monitored the transmission spectrum from a broadband light source, which displayed a strong interference signal. After data collection, we applied a phase analysis of the interference optical spectrum. We here report the results on two fabricated, BTOFs with different interference spectrum characteristics; we analyzed the signal based on the interference between a high-order modal component and the core fiber mode. The sensor exhibited a linear response for magnetic field increments, and we achieved a phase sensitivity of around 0.28 rad/mT. The sensing setup presented remote sensing operation and low-cost transducer magnetic material.

  4. Narrowband interrogation of plasmonic optical fiber biosensors based on spectral combs

    Science.gov (United States)

    González-Vila, Álvaro; Kinet, Damien; Mégret, Patrice; Caucheteur, Christophe

    2017-11-01

    Gold-coated tilted fiber Bragg gratings can probe surface Plasmon polaritons with high resolution and sensitivity. In this work, we report two configurations to interrogate such plasmonic biosensors, with the aim of providing more efficient alternatives to the widespread spectrometer-based techniques. To this aim, the interrogation is based on measuring the optical power evolution of the cladding modes with respect to surrounding refractive index changes instead of computing their wavelength shift. Both setups are composed of a broadband source and a photodiode and enable a narrowband interrogation around the cladding mode that excites the surface Plasmon resonance. The first configuration makes use of a uniform fiber Bragg grating to filter the broadband response of the source in a way that the final interrogation is based on an intensity modulation measured in transmission. The second setup uses a uniform fiber grating too, but located beyond the sensor and acting as a selective optical mirror, so the interrogation is carried out in reflection. Both configurations are compared, showing interesting differential features. The first one exhibits a very high sensitivity while the second one has an almost temperature-insensitive behavior. Hence, the choice of the most appropriate method will be driven by the requirements of the target application.

  5. The PPP Precision Analysis Based on BDS Regional Navigation System

    Directory of Open Access Journals (Sweden)

    ZHU Yongxing

    2015-04-01

    Full Text Available BeiDou navigation satellite system(BDS has opened service in most of the Asia-Pacific region, it offers the possibility to break the technological monopoly of GPS in the field of high-precision applications, so its performance of precise point positioning (PPP has been a great concern. Firstly, the constellation of BeiDou regional navigation system and BDS/GPS tracking network is introduced. Secondly, the precise ephemeris and clock offset accuracy of BeiDou satellite based on domestic tracking network is analyzed. Finally, the static and kinematic PPP accuracy is studied, and compared with the GPS. The actual measured numerical example shows that the static and kinematic PPP based on BDS can achieve centimeter-level and decimeter-level respectively, reaching the current level of GPS precise point positioning.

  6. Approaches to contactless optical thermometer in the NIR spectral range based on Nd{sup 3+} doped crystalline nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Kaldvee, K.; Nefedova, A.V. [Institute of Physics, University of Tartu, W. Ostwaldi st. 1, Tartu 50411 (Estonia); Fedorenko, S.G. [Voevodsky Institute of Chemical Kinetics and Combustion SB RAS, Novosibirsk 630090 (Russian Federation); Vanetsev, A.S. [Institute of Physics, University of Tartu, W. Ostwaldi st. 1, Tartu 50411 (Estonia); Prokhorov General Physics Institute RAS, Vavilov st. 38, Moscow 119991 (Russian Federation); Orlovskaya, E.O. [Prokhorov General Physics Institute RAS, Vavilov st. 38, Moscow 119991 (Russian Federation); Puust, L.; Pärs, M.; Sildos, I. [Institute of Physics, University of Tartu, W. Ostwaldi st. 1, Tartu 50411 (Estonia); Ryabova, A.V. [Prokhorov General Physics Institute RAS, Vavilov st. 38, Moscow 119991 (Russian Federation); National Research Nuclear University Moscow Engineering Physics Institute, Kashirskoe Highway, 31, Moscow 115409 (Russian Federation); Orlovskii, Yu.V., E-mail: orlovski@Lst.gpi.ru [Institute of Physics, University of Tartu, W. Ostwaldi st. 1, Tartu 50411 (Estonia); Prokhorov General Physics Institute RAS, Vavilov st. 38, Moscow 119991 (Russian Federation)

    2017-03-15

    The fluorescence kinetics and spectral intensity ratio (FIR) methods for contactless optical temperature measurement in the NIR spectral range with Nd{sup 3+} doped YAG micro- and YPO{sub 4} nanocrystals are considered and the problems are revealed. The requirements for good temperature RE doped crystalline nanoparticles sensor are formulated.

  7. Object Classification Based on Analysis of Spectral Characteristics of Seismic Signal Envelopes

    Science.gov (United States)

    Morozov, Yu. V.; Spektor, A. A.

    2017-11-01

    A method for classifying moving objects having a seismic effect on the ground surface is proposed which is based on statistical analysis of the envelopes of received signals. The values of the components of the amplitude spectrum of the envelopes obtained applying Hilbert and Fourier transforms are used as classification criteria. Examples illustrating the statistical properties of spectra and the operation of the seismic classifier are given for an ensemble of objects of four classes (person, group of people, large animal, vehicle). It is shown that the computational procedures for processing seismic signals are quite simple and can therefore be used in real-time systems with modest requirements for computational resources.

  8. Ensemble empirical mode decomposition based fluorescence spectral noise reduction for low concentration PAHs

    Science.gov (United States)

    Wang, Shu-tao; Yang, Xue-ying; Kong, De-ming; Wang, Yu-tian

    2017-11-01

    A new noise reduction method based on ensemble empirical mode decomposition (EEMD) is proposed to improve the detection effect for fluorescence spectra. Polycyclic aromatic hydrocarbons (PAHs) pollutants, as a kind of important current environmental pollution source, are highly oncogenic. Using the fluorescence spectroscopy method, the PAHs pollutants can be detected. However, instrument will produce noise in the experiment. Weak fluorescent signals can be affected by noise, so we propose a way to denoise and improve the detection effect. Firstly, we use fluorescence spectrometer to detect PAHs to obtain fluorescence spectra. Subsequently, noises are reduced by EEMD algorithm. Finally, the experiment results show the proposed method is feasible.

  9. Performance Analysis of Spectral Amplitude Coding Based OCDMA System with Gain and Splitter Mismatch

    Science.gov (United States)

    Umrani, Fahim A.; Umrani, A. Waheed; Umrani, Naveed A.; Memon, Kehkashan A.; Kalwar, Imtiaz Hussain

    2013-09-01

    This paper presents the practical analysis of the optical code-division multiple-access (O-CDMA) systems based on perfect difference codes. The work carried out use SNR criterion to select the optimal value of avalanche photodiodes (APD) gain and shows how the mismatch in the splitters and gains of the APD used in the transmitters and receivers of network can degrade the BER performance of the system. The investigations also reveal that higher APD gains are not suitable for such systems even at higher powers. The system performance, with consideration of shot noise, thermal noise, bulk and surface leakage currents is also investigated.

  10. Photovoltaic spectral responsivity measurements

    Energy Technology Data Exchange (ETDEWEB)

    Emery, K.; Dunlavy, D.; Field, H.; Moriarty, T. [National Renewable Energy Lab., Golden, CO (United States)

    1998-09-01

    This paper discusses the various elemental random and nonrandom error sources in typical spectral responsivity measurement systems. The authors focus specifically on the filter and grating monochrometer-based spectral responsivity measurement systems used by the Photovoltaic (PV) performance characterization team at NREL. A variety of subtle measurement errors can occur that arise from a finite photo-current response time, bandwidth of the monochromatic light, waveform of the monochromatic light, and spatial uniformity of the monochromatic and bias lights; the errors depend on the light source, PV technology, and measurement system. The quantum efficiency can be a function of he voltage bias, light bias level, and, for some structures, the spectral content of the bias light or location on the PV device. This paper compares the advantages and problems associated with semiconductor-detector-based calibrations and pyroelectric-detector-based calibrations. Different current-to-voltage conversion and ac photo-current detection strategies employed at NREL are compared and contrasted.

  11. Two 8-Hydroxyquinolinate Based Supramolecular Coordination Compounds: Synthesis, Structures and Spectral Properties

    Directory of Open Access Journals (Sweden)

    Chengfeng Zhu

    2017-03-01

    Full Text Available Two new Cr(III complexes based on 2-substituted 8-hydroxyquinoline ligands, namely [Cr(L13] (1, (HL1=(E-2-[2-(4-nitro-phenyl-vinyl]-8-hydroxy-quinoline and [Cr(L23] (2, (HL2=(E-2-[2-(4-chloro-phenylvinyl]-8-hydroxy-quinoline, were prepared by a facile hydrothermal method and characterized thoroughly by single crystal X-ray diffraction, powder X-ray diffraction, FTIR, TGA, ESI-MS, UV-Visible absorption spectra and fluorescence emission spectra. Single crystal X-ray diffraction analyses showed that the two compounds featured 3D supramolecular architectures constructed from noncovalent interactions, such as π···π stacking, C-H···π, C-H···O, C-Cl···π, C-H···Cl interactions. The thermogravimetric analysis and ESI-MS study of compounds 1 and 2 suggested that the Cr(III complexes possessed good stability both in solid and solution. In addition, the ultraviolet and fluorescence response of the HL1 and HL2 shown marked changes upon their complexation with Cr(III ion, which indicated that the two 8-hydroxyquinolinate based ligand are promising heavy metal chelating agent for Cr3+.

  12. Spectral information enhancement using wavelet-based iterative filtering for in vivo gamma spectrometry.

    Science.gov (United States)

    Paul, Sabyasachi; Sarkar, P K

    2013-04-01

    Use of wavelet transformation in stationary signal processing has been demonstrated for denoising the measured spectra and characterisation of radionuclides in the in vivo monitoring analysis, where difficulties arise due to very low activity level to be estimated in biological systems. The large statistical fluctuations often make the identification of characteristic gammas from radionuclides highly uncertain, particularly when interferences from progenies are also present. A new wavelet-based noise filtering methodology has been developed for better detection of gamma peaks in noisy data. This sequential, iterative filtering method uses the wavelet multi-resolution approach for noise rejection and an inverse transform after soft 'thresholding' over the generated coefficients. Analyses of in vivo monitoring data of (235)U and (238)U were carried out using this method without disturbing the peak position and amplitude while achieving a 3-fold improvement in the signal-to-noise ratio, compared with the original measured spectrum. When compared with other data-filtering techniques, the wavelet-based method shows the best results.

  13. Predicting the effect of spectral subtraction on the speech recognition threshold based on the signal-to-noise ratio in the envelope domain

    DEFF Research Database (Denmark)

    Jørgensen, Søren; Dau, Torsten

    2011-01-01

    rarely been evaluated perceptually in terms of speech intelligibility. This study analyzed the effects of the spectral subtraction strategy proposed by Berouti at al. [ICASSP 4 (1979), 208-211] on the speech recognition threshold (SRT) obtained with sentences presented in stationary speech-shaped noise....... The SRT was measured in five normal-hearing listeners in six conditions of spectral subtraction. The results showed an increase of the SRT after processing, i.e. a decreased speech intelligibility, in contrast to what is predicted by the Speech Transmission Index (STI). Here, another approach is proposed......, denoted the speech-based envelope power spectrum model (sEPSM) which predicts the intelligibility based on the signal-to-noise ratio in the envelope domain. In contrast to the STI, the sEPSM is sensitive to the increased amount of the noise envelope power as a consequence of the spectral subtraction...

  14. The spectral positioning algorithm of new spectrum vehicle based on convex programming in wireless sensor network

    Science.gov (United States)

    Zhang, Yongjun; Lu, Zhixin

    2017-10-01

    Spectrum resources are very precious, so it is increasingly important to locate interference signals rapidly. Convex programming algorithms in wireless sensor networks are often used as localization algorithms. But in view of the traditional convex programming algorithm is too much overlap of wireless sensor nodes that bring low positioning accuracy, the paper proposed a new algorithm. Which is mainly based on the traditional convex programming algorithm, the spectrum car sends unmanned aerial vehicles (uses) that can be used to record data periodically along different trajectories. According to the probability density distribution, the positioning area is segmented to further reduce the location area. Because the algorithm only increases the communication process of the power value of the unknown node and the sensor node, the advantages of the convex programming algorithm are basically preserved to realize the simple and real-time performance. The experimental results show that the improved algorithm has a better positioning accuracy than the original convex programming algorithm.

  15. Noninvasive spectral imaging of skin chromophores based on multiple regression analysis aided by Monte Carlo simulation

    Science.gov (United States)

    Nishidate, Izumi; Wiswadarma, Aditya; Hase, Yota; Tanaka, Noriyuki; Maeda, Takaaki; Niizeki, Kyuichi; Aizu, Yoshihisa

    2011-08-01

    In order to visualize melanin and blood concentrations and oxygen saturation in human skin tissue, a simple imaging technique based on multispectral diffuse reflectance images acquired at six wavelengths (500, 520, 540, 560, 580 and 600nm) was developed. The technique utilizes multiple regression analysis aided by Monte Carlo simulation for diffuse reflectance spectra. Using the absorbance spectrum as a response variable and the extinction coefficients of melanin, oxygenated hemoglobin, and deoxygenated hemoglobin as predictor variables, multiple regression analysis provides regression coefficients. Concentrations of melanin and total blood are then determined from the regression coefficients using conversion vectors that are deduced numerically in advance, while oxygen saturation is obtained directly from the regression coefficients. Experiments with a tissue-like agar gel phantom validated the method. In vivo experiments with human skin of the human hand during upper limb occlusion and of the inner forearm exposed to UV irradiation demonstrated the ability of the method to evaluate physiological reactions of human skin tissue.

  16. Fusion of MultiSpectral and Panchromatic Images Based on Morphological Operators.

    Science.gov (United States)

    Restaino, Rocco; Vivone, Gemine; Dalla Mura, Mauro; Chanussot, Jocelyn

    2016-04-20

    Nonlinear decomposition schemes constitute an alternative to classical approaches for facing the problem of data fusion. In this paper we discuss the application of this methodology to a popular remote sensing application called pansharpening, which consists in the fusion of a low resolution multispectral image and a high resolution panchromatic image. We design a complete pansharpening scheme based on the use of morphological half gradients operators and demonstrate the suitability of this algorithm through the comparison with state of the art approaches. Four datasets acquired by the Pleiades, Worldview-2, Ikonos and Geoeye-1 satellites are employed for the performance assessment, testifying the effectiveness of the proposed approach in producing top-class images with a setting independent of the specific sensor.

  17. Application of model-based spectral analysis to wind-profiler radar observations

    Directory of Open Access Journals (Sweden)

    E. Boyer

    Full Text Available A classical way to reduce a radar’s data is to compute the spectrum using FFT and then to identify the different peak contributions. But in case an overlapping between the different echoes (atmospheric echo, clutter, hydrometeor echo. . . exists, Fourier-like techniques provide poor frequency resolution and then sophisticated peak-identification may not be able to detect the different echoes. In order to improve the number of reduced data and their quality relative to Fourier spectrum analysis, three different methods are presented in this paper and applied to actual data. Their approach consists of predicting the main frequency-components, which avoids the development of very sophisticated peak-identification algorithms. The first method is based on cepstrum properties generally used to determine the shift between two close identical echoes. We will see in this paper that this method cannot provide a better estimate than Fourier-like techniques in an operational use. The second method consists of an autoregressive estimation of the spectrum. Since the tests were promising, this method was applied to reduce the radar data obtained during two thunder-storms. The autoregressive method, which is very simple to implement, improved the Doppler-frequency data reduction relative to the FFT spectrum analysis. The third method exploits a MUSIC algorithm, one of the numerous subspace-based methods, which is well adapted to estimate spectra composed of pure lines. A statistical study of performances of this method is presented, and points out the very good resolution of this estimator in comparison with Fourier-like techniques. Application to actual data confirms the good qualities of this estimator for reducing radar’s data.

    Key words. Meteorology and atmospheric dynamics (tropical meteorology- Radio science (signal processing- General (techniques applicable in three or more fields

  18. Application of model-based spectral analysis to wind-profiler radar observations

    Energy Technology Data Exchange (ETDEWEB)

    Boyer, E. [ENS, Cachan (France). LESiR; Petitdidier, M.; Corneil, W. [CETP, Velizy (France); Adnet, C. [THALES Air Dfense, Bagneux (France); Larzabal, P. [ENS, Cachan (France). LESiR; IUT, Cachan (France). CRIIP

    2001-08-01

    A classical way to reduce a radar's data is to compute the spectrum using FFT and then to identify the different peak contributions. But in case an overlapping between the different echoes (atmospheric echo, clutter, hydrometer echo..) exists, Fourier-like techniques provide poor frequency resolution and then sophisticated peak-identification may not be able to detect the different echoes. In order to improve the number of reduced data and their quality relative to Fourier spectrum analysis, three different methods are presented in this paper and applied to actual data. Their approach consists of predicting the main frequency-components, which avoids the development of very sophisticated peak-identification algorithms. The first method is based on cepstrum properties generally used to determine the shift between two close identical echoes. We will see in this paper that this method cannot provide a better estimate than Fourier-like techniques in an operational use. The second method consists of an autoregressive estimation of the spectrum. Since the tests were promising, this method was applied to reduce the radar data obtained during two thunderstorms. The autoregressive method, which is very simple to implement, improved the Doppler-frequency data reduction relative to the FFT spectrum analysis. The third method exploits a MUSIC algorithm, one of the numerous subspace-based methods, which is well adapted to estimate spectra composed of pure lines. A statistical study of performances of this method is presented, and points out the very good resolution of this estimator in comparison with Fourier-like techniques. Application to actual data confirms the good qualities of this estimator for reducing radar's data. (orig.)

  19. A supervised contextual classifier based on a region-growth algorithm

    DEFF Research Database (Denmark)

    Lira, Jorge; Maletti, Gabriela Mariel

    2002-01-01

    A supervised classification scheme to segment optical multi-spectral images has been developed. In this classifier, an automated region-growth algorithm delineates the training sets. This algorithm handles three parameters: an initial pixel seed, a window size and a threshold for each class. A su...

  20. [Value of quantitative iodine-based material decomposition images with gemstone spectral CT imaging in the follow-up of patients with hepatocellular carcinoma after TACE treatment].

    Science.gov (United States)

    Xing, Gusheng; Wang, Shuang; Li, Chenrui; Zhao, Xinming; Zhou, Chunwu

    2015-03-01

    To investigate the value of quantitative iodine-based material decomposition images with gemstone spectral CT imaging in the follow-up of patients with hepatocellular carcinoma (HCC) after transcatheter arterial chemoebolization (TACE). Consecutive 32 HCC patients with previous TACE treatment were included in this study. For the follow-up, arterial phase (AP) and venous phase (VP) dual-phase CT scans were performed with a single-source dual-energy CT scanner (Discovery CT 750HD, GE Healthcare). Iodine concentrations were derived from iodine-based material-decomposition images in the liver parenchyma, tumors and coagulation necrosis (CN) areas. The iodine concentration difference (ICD) between the arterial-phase (AP) and venal-phase (VP) were quantitatively evaluated in different tissues.The lesion-to-normal parenchyma iodine concentration ratio (LNR) was calculated. ROC analysis was performed for the qualitative evaluation, and the area under ROC (Az) was calculated to represent the diagnostic ability of ICD and LNR. In all the 32 HCC patients, the region of interesting (ROI) for iodine concentrations included liver parenchyma (n=42), tumors (n=28) and coagulation necrosis (n=24). During the AP the iodine concentration of CNs (median value 0.088 µg/mm(3)) appeared significantly higher than that of the tumors (0.064 µg/mm(3), P=0.022) and liver parenchyma (0.048 µg/mm(3), P=0.005). But it showed no significant difference between liver parenchyma and tumors (P=0.454). During the VP the iodine concentration in hepatic parenchyma (median value 0.181 µg/mm(3)) was significantly higher than that in CNs (0.140 µg/mm(3), P=0.042). There was no significant difference between liver parenchyma and tumors, CNs and tumors (both P>0.05). The median value of ICD in CNs was 0.006 µg/mm(3), significantly lower than that of the HCC (0.201 µg/mm(3), Piodine-based material decomposition images with gemstone spectral CT imaging can improve the diagnostic efficacy of CT imaging