WorldWideScience

Sample records for surface spectral signatures

  1. Spectral Signatures of Surface Materials in Pig Buildings

    DEFF Research Database (Denmark)

    Zhang, GuoQiang; Strøm, Jan; Blanke, Mogens

    2006-01-01

    and after high-pressure water cleaning. The spectral signatures of the surface materials and dirt attached to the surfaces showed that it is possible to make discrimination and hence to classify areas that are visually clean. When spectral bands 450, 600, 700 and 800 nm are chosen, there are at least two...... the cleaning process and to minimise the amount of water and electricity consumed. This research is aimed at utilising a spectral imaging method for cleanliness detection. Consequently, information on the reflectance of building materials and contamination in different spectral ranges is important...... in the investigation. Reflectance data were sampled under controlled lighting conditions using a spectrometer communicating with a portable computer. The measurements were performed in a laboratory with materials used in a pig house for 4-5 weeks. The spectral data were collected for the surfaces before, during...

  2. Search for olivine spectral signatures on the surface of Vesta

    Science.gov (United States)

    Palomba, E.; De Sanctis, M. C.; Ammannito, E.; Capaccioni, F.; Capria, M. T.; Farina, M.; Frigeri, A.; Longobardo, A.; Tosi, F.; Zambon, F.; McSween, H. Y.; Mittlefehldt, D. W.; Russell, C. T.; Raymond, C. A.; Sunshine, J.; McCord, T. B.

    2012-04-01

    The occurrence of olivines on Vesta were first postulated from traditional petrogenetic models which suggest the formation of olivine as lower crustal cumulates. An indirect confirmation is given by their presence as a minor component in some samples of diogenite meteorites, the harzburgitic diogenites and the dunitic diogenites, and as olivine mineral clasts in howardites. Another indication for this mineral was given by interpretations of ground-based and Hubble Space Telescope observations that suggested the presence of local olivine-bearing units on the surface of Vesta. The VIR instrument onboard the DAWN mission has been mapping Vesta since July 2011. VIR acquired hyperspectral images of Vesta's surface in the wavelength range from 0.25 to 5.1 µm during Approach, Survey and High Altitude Mapping (HAMO) orbits that allowed a 2/3 of the entire asteroid surface to be mapped. The VIR operative spectral interval, resolution and coverage is suitable for the detection and mapping of any olivine rich regions that may occur on the Vesta surface. The abundance of olivine in diogenites is typically lower than 10% but some samples richer in olivine are known. However, we do not expect to have extensive exposures of olivine-rich material on Vesta. Moreover, the partial overlap of olivine and pyroxene spectral signatures will make olivine difficult to detect. Different spectral parameters have been used to map olivine on extraterrestrial bodies, and here we discuss the different approaches used, and develop new ones specifically for Vesta. Our new methods are based on combinations of the spectral parameters relative to the 1 and 2 micron bands (the most prominent spectral features of Vesta surface in the visible and the infrared), such as band center locations, band depths, band areas, band area ratios. Before the direct application to the VIR data, the efficiency of each approach is evaluated by means of analysis of laboratory spectra of HED meteorites, pyroxenes

  3. Search for Olivine Spectral Signatures on the Surface of Vesta

    Science.gov (United States)

    Palomba, E.; De Sanctis, M. C.; Ammannito, E.; Capaccioni, F.; Capria, M. T.; Farina, M.; Frigeri, A.; Longobardo, A.; Tosi, F.; Zambon, F.; McSween, H. Y.; Mittlefehldt, D. W.; Russell, C. T.; Raymond, C. A.; Sunshine, J.; McCord, T. B.

    2012-01-01

    The occurrence of olivines on Vesta were first postulated from traditional petrogenetic models which suggest the formation of olivine as lower crustal cumulates. An indirect confirmation is given by their presence as a minor component in some samples of diogenite meteorites, the harzburgitic diogenites and the dunitic diogenites, and as olivine mineral clasts in howardites. Another indication for this mineral was given by interpretations of groundbased and Hubble Space Telescope observations that suggested the presence of local olivine-bearing units on the surface of Vesta. The VIR instrument onboard the DAWN mission has been mapping Vesta since July 2011. VIR acquired hyperspectral images of Vesta s surface in the wavelength range from 0.25 to 5.1 m during Approach, Survey and High Altitude Mapping (HAMO) orbits that allowed a 2/3 of the entire asteroid surface to be mapped. The VIR operative spectral interval, resolution and coverage is suitable for the detection and mapping of any olivine rich regions that may occur on the Vesta surface. The abundance of olivine in diogenites is typically lower than 10% but some samples richer in olivine are known. However, we do not expect to have extensive exposures of olivine-rich material on Vesta. Moreover, the partial overlap of olivine and pyroxene spectral signatures will make olivine difficult to detect. Different spectral parameters have been used to map olivine on extraterrestrial bodies, and here we discuss the different approaches used, and develop new ones specifically for Vesta. Our new methods are based on combinations of the spectral parameters relative to the 1 and 2 micron bands (the most prominent spectral features of Vesta surface in the visible and the infrared), such as band center locations, band depths, band areas, band area ratios. Before the direct application to the VIR data, the efficiency of each approach is evaluated by means of analysis of laboratory spectra of HED meteorites, pyroxenes, olivines

  4. Spectral Signatures of Surface Materials in Pig Buildings

    DEFF Research Database (Denmark)

    Zhang, GuoQiang; Strøm, Jan; Blanke, Mogens

    2006-01-01

    Manual cleaning of pig production buildings based on high-pressure water cleaners is unappealing to workers, because it is tedious and health threatening. To replace manual cleaning, a few cleaning robots have been commercialised. With no cleanliness sensor available, the operation of these robots...... spectral bands for each type of the materials, in which the spectral signals can be used for discrimination of dirty and clean condition of the surfaces. (c) 2006 IAgrE. All rights reserved Published by Elsevier Ltd...

  5. Spectral signatures of chirality

    DEFF Research Database (Denmark)

    Pedersen, Jesper Goor; Mortensen, Asger

    2009-01-01

    We present a new way of measuring chirality, via the spectral shift of photonic band gaps in one-dimensional structures. We derive an explicit mapping of the problem of oblique incidence of circularly polarized light on a chiral one-dimensional photonic crystal with negligible index contrast...... to the formally equivalent problem of linearly polarized light incident on-axis on a non-chiral structure with index contrast. We derive analytical expressions for the first-order shifts of the band gaps for negligible index contrast. These are modified to give good approximations to the band gap shifts also...

  6. Spectral flow, index and the signature operator

    CERN Document Server

    Azzali, Sara

    2009-01-01

    We relate the spectral flow to the index for paths of selfadjoint Breuer-Fredholm operators affiliated to a semifinite von Neumann algebra, generalizing results of Robbin-Salamon and Pushnitski. Then we prove the vanishing of the von Neumann spectral flow for the tangential signature operator of a foliated manifold when the metric is varied. We conclude that the tangential signature of a foliated manifold with boundary does not depend on the metric. In the Appendix we reconsider integral formulas for the spectral flow of paths of bounded operators.

  7. Temporal shape analysis via the spectral signature.

    Science.gov (United States)

    Bernardis, Elena; Konukoglu, Ender; Ou, Yangming; Metaxas, Dimitris N; Desjardins, Benoit; Pohl, Kilian M

    2012-01-01

    In this paper, we adapt spectral signatures for capturing morphological changes over time. Advanced techniques for capturing temporal shape changes frequently rely on first registering the sequence of shapes and then analyzing the corresponding set of high dimensional deformation maps. Instead, we propose a simple encoding motivated by the observation that small shape deformations lead to minor refinements in the spectral signature composed of the eigenvalues of the Laplace operator. The proposed encoding does not require registration, since spectral signatures are invariant to pose changes. We apply our representation to the shapes of the ventricles extracted from 22 cine MR scans of healthy controls and Tetralogy of Fallot patients. We then measure the accuracy score of our encoding by training a linear classifier, which outperforms the same classifier based on volumetric measurements.

  8. Spectral signatures of hydrilla from a tank and field setting

    Institute of Scientific and Technical Information of China (English)

    Alfonso BLANCO; John J.QU; William E.ROPER

    2012-01-01

    The invasion of hydrilla in many waterways has caused significant problems resulting in high maintenance costs for eradicating this invasive aquatic weed.Present identification methods employed for detecting hydrilla invasions such as aerial photography and videos are difficult,costly,and time consuming.Remote sensing has been used for assessing wetlands and other aquatic vegetation,but very little information is available for detecting hydrilla invasions in coastal estuaries and other water bodies.The objective of this study is to construct a library of spectral signatures for identifying and classifying hydrilla invasions.Spectral signatures of hydrilla were collected from an experimental tank and field locations in a coastal estuary in the upper Chesapeake Bay.These measurements collected from the experimental tank,resulted in spectral signatures with an average peak surface reflectance in the near-infrared (NIR) region of 16% at a wavelength of 818 nm.However,the spectral measurements,collected in the estuary,resulted in a very different spectral signature with two surface reflectance peaks of 6% at wavelengths of 725 nm and 818 nm.The difference in spectral signatures between sites are a result of the components in the water column in the estuary because of increased turbidity (e.g.,nutrients,dissolved matter and suspended matter),and canopy being lower (submerged) in the water column.Spectral signatures of hydrilla observed in the tank and the field had similar characteristics with low reflectance in visible region of the spectrum from 400 to 700 nm,but high in the NIR region from 700 to 900 nm.

  9. A coarse-grained spectral signature generator

    Science.gov (United States)

    Lam, K. P.; Austin, J. C.; Day, C. R.

    2007-01-01

    This paper investigates the method for object fingerprinting in the context of element specific x-ray imaging. In particular, the use of spectral descriptors that are illumination invariant and viewpoint independent for pattern identification was examined in some detail. To improve generating the relevant "signature", the spectral descriptor constructed is enhanced with a differentiator which has built-in noise filtration capability and good localisation properties, thus facilitating the extraction of element specific features at a coarse-grained level. In addition to the demonstrable efficacy in identifying significant image intensity transitions that are associated with the underlying physical process of interest, the method has the distinct advantage of being conceptually simple and computationally efficient. These latter properties allow the descriptor to be further utilised by an intelligent system capable of performing a fine-grained analysis of the extracted pattern signatures. The performance of the spectral descriptor has been studied in terms of the quality of the signature vectors that it generated, quantitatively based on the established framework of Spectral Information Measure (SIM). Early results suggested that such a multiscale approach of image sequence analysis offers a considerable potential for real-time applications.

  10. Spectral induced polarization signature of contaminated soil

    Science.gov (United States)

    Schwartz, N.; Huisman, J. A.; Shefer, I.; Furman, A.

    2012-04-01

    Spectral induced polarization (SIP) signatures of porous media contaminated with non aqueous phase liquids (NAPL) were measured using an accurate impedance meter. The samples were prepared by mixing air-dried sand with 15% by weight of bentonite clay, tap water and either diesel fuel or motor oil. Next, the soil was packed in a column and left for 24 hr before electrical measurements were performed. For all the samples, water saturation was constant (Sw = 0.47) and the NAPL saturation was 0 (control), 5, or 15 percent. Counter-intuitively, the results show that addition of NAPL to the porous media resulted in an increase of the real part of the complex conductivity. Evidently, for each type of contaminant, an increase in the contaminant saturation resulted in an increase in the real part of the conductivity. The imaginary part of the complex conductivity showed a reversed behavior: higher NAPL saturation resulted in a reduction of the imaginary part of the complex conductivity. For both the real and the imaginary part of the complex conductivity, the effect of NAPL on the complex electrical conductivity was more significant for motor oil than for diesel fuel. In addition to the electrical measurements, we also performed an extraction experiment to examine the effect of the presence of NAPL on the electrical conductivity (EC) of the pore water. The results from the extraction experiment showed that addition of NAPL to the porous media resulted in an increase of the pore water EC. We argue that this increase in the real part of the complex conductivity is related to adsorption of organic polar compounds from the NAPL onto the mineral surface and the associated release of inorganic ions from the mineral surface to the pore water. These exchange processes affect both the surface and the pore water conductivity. In addition, we suggest that the decrease in polarization (associated with the imaginary part of the complex conductivity) of the NAPL contaminated porous media

  11. Understanding Complex Spectral Signatures of Embedded Excess Protons in Molecular Scaffolds with Third Order Corrections to the Harmonic Potential Surface

    Science.gov (United States)

    Deblase, Andrew F.; Johnson, Mark A.; Lectka, Thomas; Wang, Xun; Jordan, Kenneth D.; McCoy, Anne B.

    2013-06-01

    Overtones and combination bands observed in vibrational predissociation spectra of cold ions can often be anticipated by expanding the potential energy surface to third order. This is achieved by relating the third derivatives to the matrix elements that couple the allowed and forbidden states in the harmonic basis. Such a strategy has been successful in predicting Fermi resonances in formic acid clusters and some charged H-bonded complexes. Furthermore, third order couplings have been used to develop a vibrational adiabatic model in which excitation of a bright state is distributed over a Franck-Condon envelop of a lower energy mode, such as a water rocking against triatomic domains of molecular anions. Previous applications include the analysis of long vibrational progressions of soft modes in the OH stretching region of the actetate-water binary complex. Here we explore to extent to which this order of correction captures the irregular patterns associated with intramolecular proton bonds.

  12. Mid-IR Spectral Search for Salt SIgnatures on Europa

    Science.gov (United States)

    Becker, Tracy M.; Retherford, Kurt D.; Hanley, Jennifer; Greathouse, Thomas K.; Tsang, Constantine; Roth, Lorenz

    2016-10-01

    We present mid-IR spectra of Europa's leading and trailing hemispheres obtained with the NASA IRTF/TEXES instrument on March 28 and March 30, 2015. The observations span from ~10 - 11 microns with a resolving power of R ~2500. Few observations of Europa have been made at these wavelengths, and the high spectral resolution of the instrument enables the identification of distinguishing spectral features in this relatively unexplored bandpass. While the leading hemisphere of Europa consists of relatively pure water ice, the trailing hemisphere's surface contains a mix of ice and some other component, causing the surface to appear reddish at visible wavelengths. We compare the spectra from the trailing hemisphere with those from the leading, pure-ice hemisphere and with recent laboratory measurements of chlorinated salts, which have distinct spectral signatures at these wavelengths. We find that the signal obtained from Europa's leading hemisphere is 5-10 times lower than the signal obtained from the trailing hemisphere, likely due to a temperature difference between the hemispheres. We discern several spectral features that are present in the trailing hemisphere but not in the spectra of the leading hemisphere, though the explanation for these features is not yet apparent.

  13. Spectral signature verification using statistical analysis and text mining

    Science.gov (United States)

    DeCoster, Mallory E.; Firpi, Alexe H.; Jacobs, Samantha K.; Cone, Shelli R.; Tzeng, Nigel H.; Rodriguez, Benjamin M.

    2016-05-01

    In the spectral science community, numerous spectral signatures are stored in databases representative of many sample materials collected from a variety of spectrometers and spectroscopists. Due to the variety and variability of the spectra that comprise many spectral databases, it is necessary to establish a metric for validating the quality of spectral signatures. This has been an area of great discussion and debate in the spectral science community. This paper discusses a method that independently validates two different aspects of a spectral signature to arrive at a final qualitative assessment; the textual meta-data and numerical spectral data. Results associated with the spectral data stored in the Signature Database1 (SigDB) are proposed. The numerical data comprising a sample material's spectrum is validated based on statistical properties derived from an ideal population set. The quality of the test spectrum is ranked based on a spectral angle mapper (SAM) comparison to the mean spectrum derived from the population set. Additionally, the contextual data of a test spectrum is qualitatively analyzed using lexical analysis text mining. This technique analyzes to understand the syntax of the meta-data to provide local learning patterns and trends within the spectral data, indicative of the test spectrum's quality. Text mining applications have successfully been implemented for security2 (text encryption/decryption), biomedical3 , and marketing4 applications. The text mining lexical analysis algorithm is trained on the meta-data patterns of a subset of high and low quality spectra, in order to have a model to apply to the entire SigDB data set. The statistical and textual methods combine to assess the quality of a test spectrum existing in a database without the need of an expert user. This method has been compared to other validation methods accepted by the spectral science community, and has provided promising results when a baseline spectral signature is

  14. Extraction of pure spectral signatures and corresponding chemical maps from EPR imaging data sets: identifying defects on a CaF2 surface due to a laser beam exposure.

    Science.gov (United States)

    Abou Fadel, Maya; Zhang, Xin; de Juan, Anna; Tauler, Roma; Vezin, Hervé; Duponchel, Ludovic

    2015-04-07

    A calcium fluoride (CaF2) plate was exposed to pulsed laser irradiations inducing surface morphological and ionization changes on its surface. More precisely surface damages mainly correspond to intrinsic defects. Electron paramagnetic resonance (EPR) hyperspectral imaging is a powerful technique able to characterize the defects formed on the CaF2 surface. Indeed, EPR hyperspectral images provide spatial and spectral information about the sample studied. In fact, these images possess a great potential to obtain accurate and reliable knowledge about the chemical composition and the distribution of the component due to the presence of the spatial aspect. However, the complexity of such hyperspectral data sets imposes the use of advanced chemometric tools to extract valuable information on the considered physicochemical system. Therefore, Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS) is proposed to identify and locate the different constituents in the images. The originality of this work is that it reports on the application of MCR-ALS, for the first time, on electron paramagnetic resonance (EPR) imaging data sets that will furnish the distribution maps and the spectral signatures of all components present in the sample. The results show the identification of different intrinsic defects on a CaF2 sample from the sole information in the raw image measurements and, therefore, confirm the potential of this methodology and the important role of spatial information contained in the image.

  15. 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.

  16. Spectral signatures for swash on reflective, intermediate and dissipative beaches

    DEFF Research Database (Denmark)

    Hughes, Michael G; Aagaard, Troels; Baldock, Tom E

    2014-01-01

    In this paper we synthesise a large data set gathered from a wide variety of field deployments and integrate it with previously published results to identify the spectral signatures of swash from contrasting beach types. The field data set includes the full range of micro-tidal beach types...... the three beach types. Swash energy at short-wave frequencies is dominant on reflective and intermediate beaches and swash at long-wave frequencies is dominant on dissipative beaches; consistent with previously reported spectral signatures for the surf zone on these beach types. The available swash spectra...... were classified using an automated algorithm (CLARA) into five different classes. The ordered classes represent an evolution in the spectrum shape, described by a frequency downshifting of the energy peak from the short-wave into the long-wave frequency band and an increase in the long-wave swash...

  17. Discrimination of fungal infections on grape berries via spectral signatures

    Science.gov (United States)

    Molitor, Daniel; Griesser, Michaela; Schütz, Erich; Khuen, Marie-Therese; Schefbeck, Christa; Ronellenfitsch, Franz Kai; Schlerf, Martin; Beyer, Marco; Schoedl-Hummel, Katharina; Anhalt, Ulrike; Forneck, Astrid

    2016-04-01

    The fungal pathogens Botrytis cinerea and Penicillium expansum are causing economic damages on grapevine worldwide. Especially the simultaneous occurrence of both often results in off-flavours highly threatening wine quality. For the classification of grape quality as well as for the determination of targeted enological treatments, the knowledge of the level of fungal attack is of highest interest. However, visual assessment and pathogen discrimination are cost-intensive. Consequently, a pilot laboratory study aimed at (i) detecting differences in spectral signatures between grape berry lots with different levels of infected berries (B. cinerea and/or P. expansum) and (ii) detecting links between spectral signatures and biochemical as well as quantitative molecular markers for fungal attack. To this end, defined percentages (infection levels) of table grape berries were inoculated with fungal spore suspensions. Spectral measurements were taken using a FieldSpec 3 Max spectroradiometer (ASD Inc., Boulder/Colorado, USA) in regular intervals after inoculation. In addition, fungal attack was determined enzymatically) and quantitatively (real-time PCR). In addition, gluconic acid concentrations (as a potential markers for fungal attack) were determined photometrically. Results indicate that based on spectral signatures, a discrimination of P. expansum and B. cinerea infections as well as of different B. cinerea infection levels is possible. Real-time PCR analyses, detecting DNA levels of both fungi, showed yet a low detection level. Whereas the gluconic acid concentrations turned out to be specific for the two fungi tested (B. cinerea vs. P. expansum) and thus may serve as a differentiating biochemical marker. Correlation analyses between spectral measurements and biological data (gluconic acid concentrations, fungi DNA) as well as further common field and laboratory trials are targeted.

  18. The spectral signature of cloud spatial structure in shortwave irradiance

    Science.gov (United States)

    Song, Shi; Schmidt, K. Sebastian; Pilewskie, Peter; King, Michael D.; Heidinger, Andrew K.; Walther, Andi; Iwabuchi, Hironobu; Wind, Gala; Coddington, Odele M.

    2017-01-01

    In this paper, we used cloud imagery from a NASA field experiment in conjunction with three-dimensional radiative transfer calculations to show that cloud spatial structure manifests itself as a spectral signature in shortwave irradiance fields – specifically in transmittance and net horizontal photon transport in the visible and near-ultraviolet wavelength range. We found a robust correlation between the magnitude of net horizontal photon transport (H) and its spectral dependence (slope), which is scale-invariant and holds for the entire pixel population of a domain. This was surprising at first given the large degree of spatial inhomogeneity. We prove that the underlying physical mechanism for this phenomenon is molecular scattering in conjunction with cloud spatial structure. On this basis, we developed a simple parameterization through a single parameter ε, which quantifies the characteristic spectral signature of spatial inhomogeneities. In the case we studied, neglecting net horizontal photon transport leads to a local transmittance bias of ±12–19 %, even at the relatively coarse spatial resolution of 20 km. Since three-dimensional effects depend on the spatial context of a given pixel in a nontrivial way, the spectral dimension of this problem may emerge as the starting point for future bias corrections. PMID:28824698

  19. Integrated ray tracing simulation of spectral bio-signatures from full 3D earth model

    Science.gov (United States)

    Ryu, Dongok; Seong, Sehyun; Lee, Jae-Min; Hong, Jinsuk; Jeong, Soomin; Jeong, Yukyeong; Kim, Sug-Whan

    2009-08-01

    Accurate identification and understanding of spectral bio-signatures from possible extra terrestrial planets have received an ever increasing attention from both astronomy and space science communities in recent years. In pursuance of this subject, one of the most important scientific breakthroughs would be to obtain the detailed understanding on spectral biosignatures of the Earth, as it serves as a reference datum for accurate interpretation of collapsed (in temporal and spatial domains) information from the spectral measurement using TPF instruments. We report a new Integrated Ray Tracing (IRT) model capable of computing various spectral bio-signatures as they are observed from the Earth surface. The model includes the Sun, the full 3-D Earth, and an optical instrument, all combined into single ray tracing environment in real scale. In particular, the full 3-D Earth surface is constructed from high resolution coastal line data and defined with realistic reflectance and BSDF characteristics depending on wavelength, vegetation types and their distributions. We first examined the model validity by confirming the imaging and radiometric performance of the AmonRa visible channel camera, simulating the Earth observation from the L1 halo orbit. We then computed disk averaged spectra, light curves and NDVI indexes, leading to the construction of the observed disk averaged spectra at the AmonRa instrument detector plane. The model, computational procedure and the simulation results are presented. The future plan for the detailed spectral signature simulation runs for various input conditions including seasonal vegetation changes and variable cloud covers is discussed.

  20. High-Energy Spectral Signatures in $\\gamma$-Ray Bursts

    CERN Document Server

    Baring, M G

    1999-01-01

    One of the principal results obtained by the EGRET experiment aboard the Compton Gamma-Ray Observatory (CGRO) was the detection of several Gamma-ray bursts (GRBs) above 100 MeV. The broad-band spectra obtained for these bursts gave no indication of any high energy spectral attenuation that might preclude detection of bursts by ground-based Cerenkov telescopes (ACTs), thus motivating several TeV observational programs. This paper explores the expectations for the spectral properties in the TeV and sub-TeV bands for bursts, in particular how attenuation of photons by pair creation internal to the source modifies the spectrum to produce distinctive spectral signatures. The energy of spectral breaks and the associated spectral indices provide valuable information that can constrain the bulk Lorentz factor of the GRB outflow at a given time. These characteristics define palpable observational goals for ACT programs, and strongly impact the observability of bursts in the TeV band.

  1. Determining the Spectral Signature of Spatial Coherent Structures

    CERN Document Server

    Pastur, L R; Fraigneau, Y; Podvin, B

    2005-01-01

    We applied to an open flow a proper orthogonal decomposition (pod) technique, on 2D snapshots of the instantaneous velocity field, to reveal the spatial coherent structures responsible of the self-sustained oscillations observed in the spectral distribution of time series. We applied the technique to 2D planes out of 3D direct numerical simulations on an open cavity flow. The process can easily be implemented on usual personal computers, and might bring deep insights on the relation between spatial events and temporal signature in (both numerical or experimental) open flows.

  2. Evidence for the Nature of Space Weathering Spectral Signatures on Low Albedo Asteroids

    Science.gov (United States)

    Lantz, Cateline; Clark, B. E.; Barucci, M. A.

    2012-10-01

    We address an existing problem in understanding the reflected light spectral signatures of carbonaceous (low-albedo) asteroids. We know from observations of the moon and high-albedo asteroids that interplanetary surface processes (solar wind and micrometeorite bombardment) can alter the spectral properties of silicates. The problem is that we don’t understand how carbonaceous surfaces respond to surface processes. The question is, what are the spectral signatures of surface processes on low albedo asteroids? To answer this question, we need to study reflected light spectra of asteroid subsurface materials, and compare them with asteroid surface materials. In this work, we assume that primitive asteroids are the parent bodies of carbonaceous chondrites. We begin with a fairly well-established meteorite-asteroid link: several studies have found evidence that links the CM meteorites with the Ch/Cgh asteroids [Hiroi et ao. 1996; Fornasier et al. 1999]. Assuming this link, we reason that differences between spectra of particulate samples of the CM meteorites and spectra of the regolith of the asteroids can be due to either differences in textural properties, or differences caused by surface processes on the asteroid. Previous work has resulted in contradictory predictions. Asteroid color survey data analyzed by Lazzarin et al. (2006) predicted spectral reddening for low albedo asteroids. Laser irradiation experiments by Moroz et al. (1996; 2004; 2004b) indicated both reddening and blueing of various degrees. Our initial results indicate spectral blueing of up to 50%, with little to no concurrent albedo change. We used telescopic observations of 43 Ch and Cgh-type asteroids (0.4 to 2.5 microns) from Binzel, DeMeo, et al. (MIT) and Fornasier et al. (Obs. Paris). We compare them statistically with 106 CM meteorite spectra from RELAB. The goal of this work is to predict what the OSIRIS-REx mission will see at B-type asteroid (101955) 1999RQ36.

  3. Spectral and Polarization Signatures of Relativistic Shocks in Blazars

    CERN Document Server

    Boettcher, Markus

    2016-01-01

    Relativistic shocks are one of the most plausible sites of the emission of strongly variable, polarized multi-wavelength emission from relativistic jet sources such as blazars, via diffusive shock acceleration (DSA) of relativistic particles. This paper summarizes recent results on a self-consistent coupling of diffusive shock acceleration and radiation transfer in blazar jets. We demonstrate that the observed spectral energy distributions (SEDs) of blazars strongly constrain the nature of hydromagnetic turbulence responsible for pitch-angle scattering by requiring a strongly energy-dependent pitch-angle mean free path. The prominent soft X-ray excess ("Big Blue Bump") in the SED of the BL Lac object AO 0235+164 can be modelled as the signature of bulk Compton scattering of external radiation fields by the thermal electron population, which places additional constraints on the level of hydromagnetic turbulence. It has further been demonstrated that internal shocks propagating in a jet pervaded by a helical ma...

  4. Ordinary Chondrite Spectral Signatures in the 243 Ida Asteroid System

    Science.gov (United States)

    Granahan, J. C.

    2012-12-01

    The NASA Galileo spacecraft observed asteroid 243 Ida and satellite Dactyl on August 28, 1993, with the Near Infrared Mapping Spectrometer (NIMS) at wavelengths ranging from 0.7 to 5.2 micrometers[Carlson et al., 1994]. Work is being conducted to produce radiance-calibrated spectral images of 243 Ida consisting of 17-channel, 299 meters per pixel files and a 102-channel, 3.2 kilometer per pixel NIMS observations of 243 Ida for the NASA Planetary Data System (PDS). These data are currently archived in PDS as uncalibrated data number counts. Radiometric calibrated 17-channel and 102-channel NIMS spectral data files of Dactyl and light curve 243 Ida observations are also being prepared. Analysis of this infrared asteroid data has confirmed that both 243 Ida and Dactyl are S-type asteroid objects and found that their olivine and pyroxene mineral abundances are consistent with that of ordinary chondrite meteorites. Tholen [1989] identified 243 Ida and Chapman et al. [1995] identified Dactyl as S-type asteroids on the basis of spectral data ranging from 0.4 to 1.0 micrometers. S-type are described [Tholen, 1989] as asteroids with a moderate albedos, a moderate to strong absorption feature shortward of 0.7 micrometers, and moderate to nonexistent absorption features longward of 0.7 micrometers. DeMeo et al. [2009] found 243 Ida to be a Sw asteroid based on Earth-based spectral observations 0.4 to 2.5 micrometers in range. Sw is a subclass of S-type asteroids that has a space weathering spectral component [DeMeo et al., 2009]. The NIMS data 243 Ida and Dactyl processed in this study exhibit signatures consistent with the Sw designation of DeMeo et al. [2009]. Measurements of olivine and pyroxene spectral bands were also conducted for the NIMS radiance data of 243 Ida and Dactyl. Band depth and band center measurements have been used to compare S-type asteroids with those of meteorites [Dunn et al., 2010; Gaffey et al., 1993]. The 243 Ida spectra were found to be consistent

  5. Spectral Gamma-ray Signatures of Cosmological Dark Matter Annihilation

    CERN Document Server

    Bergström, L; Ullio, P; Bergstrom, Lars; Edsjo, Joakim; Ullio, Piero

    2001-01-01

    We propose a new signature for weakly interacting massive particle (WIMP) dark matter, a spectral feature in the diffuse extragalactic gamma-ray radiation. This feature, a sudden drop of the gamma-ray intensity at an energy corresponding to the WIMP mass, comes from the asymmetric distortion of the line due to WIMP annihilation into two gamma-rays caused by the cosmological redshift. Unlike other proposed searches for a line signal, this method is not very sensitive to the exact dark matter density distribution in halos and subhalos. The only requirement is that the mass distribution of substructure on small scales follows approximately the Press-Schechter law, and that smaller halos are on the average denser than large halos, which is a generic outcome of N-body simulations of Cold Dark Matter, and which has observational support. The upcoming Gamma-ray Large Area Space Telescope (GLAST) will be eminently suited to search for these spectral features. For numerical examples, we use rates computed for supersym...

  6. Pollution detection using the spectral fluorescent signatures (SFS technique

    Directory of Open Access Journals (Sweden)

    Mª Del Carmen Martín

    2014-06-01

    Full Text Available This work has been developed in the Applied Physics Department at the University of Vigo within the line of research based on the treatment of the degraded water by pollutants through the use of microalgae, reducing the emissions of greenhouse gases through the absorption of CO2 in the process and the reuse of biomass as biofuel. Remote sensing techniques have contributed to a great extent to the development of oil pollution monitoring systems. However, the available detection methods, mainly designed for spaceborne and airborne long distance inspection, are too expensive and complex to be used in an operational way by relatively unskilled personnel. In the framework of DEOSOM project (European AMPERA project, an innovative water monitoring method was proposed, in two steps: early oil spill detection using a portable shipborne laser-induced fluorescence LIDAR (LIF/LIDAR, and analysis of suspicious water samples in laboratory using the Spectral Fluorescent Signature (SFS technique. This work is focused on the second technique. This system aims to optimize the production of microalgae for biofuel and contaminant cleaning applications and was developed and tested in photo-bioreactors in the University of Vigo within the EnerBioAlgae project (SUDOE. In this project, the SFS technique was used as a diagnostic tool employing the fluorescence analyzer INSTANT-SCREENER M53UVC. The Spectral Fluorescence Signature technique (SFS is based on compounds fluorescence properties. The fluorescence intensity of a sample is measured at different excitation and emission wavelengths to produce a 3-dimensional fluorescence matrix, which can also be presented as a 2-dimensional color image where the color shows the intensity of the fluorescence. These matrices offer qualitative and quantitative information, since they can be useful for the identification of different substances from their characteristic excitation and emission spectra of fluorescence. They also

  7. Insights on the spectral signatures of RV jitter from PCA

    Science.gov (United States)

    Davis, Allen Bradford; Cisewski, Jessica; Dumusque, Xavier; Fischer, Debra; Ford, Eric B.

    2017-01-01

    Stellar activity features such as spots and faculae can mimic radial velocity (RV) motion by creating spurious time-varying centroid shifts in the stellar spectral lines. This "RV jitter" hinders the detection of large planetary signals (100 m s-1) around young, active stars, and it dominates the Keplerian signals of Earth-analogs (10 to 20 cm s-1) even around quiet stars. However, appropriate statistical techniques may be able to distinguish these phenomena by exploiting the spectral-line dependence and temporal coherence of RV jitter.We produce simulated disk-integrated time-series spectra of a rotating star with a spot, with a facula, or with a planet of various sizes using the SOAP 2.0 code, which uses real high-resolution and high-S/N spectra of the quiet solar photosphere and sunspots as a starting point. Principal component analysis (PCA) is used to identify and quantify the wavelength-dependent intensity variations of the spectra in each of these cases. We find that the PCA signatures of these three phenomena are distinct, suggesting that they can be distinguished in theory. We then lower the resolution and S/N of these simulated spectra and use PCA to quantify their information content. We find that high-resolution (R > 100,000) observations are better able to recover information in the spectra of spots and faculae than would be expected compared to an equivalent increase in S/N. This effect is especially pronounced for large spots and faculae (S ≥ 1%), suggesting that high-resolution spectrographs will be particularly well-suited for characterizing stellar activity.

  8. Spectral Induced Polarization Signature of Soil Organic Matter

    Science.gov (United States)

    Schwartz, Nimrod; Furman, Alex

    2015-04-01

    Although often composing a non-negligible fraction of soil cation exchange capacity (CEC), the impact of soil organic matter (OM) on the electrical properties of soil has not been thoroughly investigated. In this research the impact of soil OM on the spectral induced polarization (SIP) signature of soil was investigated. Electrical and chemical measurements for two experiments using the same soil, one with calcium as the dominant cation and the other with sodium, with different concentration of OM were performed. Our results show that despite the high CEC of OM, a decrease in polarization and an increase in relaxation time with increasing concentration of OM is observed. For the soil with calcium as the dominant cation, the decreases in polarization and the increase in relaxation time were stronger. We explain these non-trivial results by accounting for the interactions between the OM and the soil minerals. We suggest that the formation of organo-mineral complexes reduce ionic mobility, explaining both the decrease in polarization and the increase in relaxation time. These results demonstrate the important role of OM on SIP response of soil, and call for a further research in order to establish a new polarization model that will include the impact of OM on soil polarization.

  9. On the spectral induced polarization signature of soil organic matter

    Science.gov (United States)

    Schwartz, N.; Furman, A.

    2015-01-01

    Although often composing a non-negligible fraction of soil cation exchange capacity (CEC), the impact of soil organic matter (OM) on the electrical properties of soil has not been thoroughly investigated. In this research the impact of soil OM on the spectral induced polarization (SIP) signature of soil was investigated. Electrical and chemical measurements for two experiments using the same soil, one with calcium as the dominant cation and the other with sodium, with different concentration of OM were performed. Our results show that despite the high CEC of OM, a decrease in polarization and an increase in relaxation time with increasing concentration of OM is observed. For the soil with calcium as the dominant cation, the decreases in polarization and the increase in relaxation time were stronger. We explain these non-trivial results by accounting for the interactions between the OM and the soil minerals. We suggest that the formation of organo-mineral complexes reduce ionic mobility, explaining both the decrease in polarization and the increase in relaxation time. These results demonstrate the important role of OM on SIP response of soil, and call for a further research in order to establish a new polarization model that will include the impact of OM on soil polarization.

  10. Anomalous crater Marcia on asteroid 4 Vesta: Spectral signatures and their geological relationship

    Science.gov (United States)

    Giebner, T.; Jaumann, R.; Schroeder, S.; Krohn, K.

    2016-12-01

    DAWN Framing Camera (FC) images are used in this study to analyze the diverse spectral signatures of crater Marcia. As the FC offers high spatial resolution as well as several color filters it is well suited to resolve geological correlations on Vestas surface. Our approach comprises the analysis of images from four FC filters ( F3, F4, F5 and F6) that cover the pyroxene absorption band at 0.9 um and the comparison of Vesta data with HED meteorite spectra. We use the ratios R 750/915 (F3/F4) and R 965/830 (F5/F6) [nm] to separate HED lithologies spectrally and depict corresponding areas on HAMO mosaics ( 60 m/px). Additionally, higher resolution LAMO images ( 20 m/px) are analyzed to reveal the geologic setting. In this work, Marcia is broadly classified into three spectral regions. The first region is located in the northwestern part of the crater as well as in the central peak area and shows the most HED-like signature within the Marcia region. The other two regions, with one of them also describing Marcia ejecta, are spectrally further away from HED lithologies and likely display a mixing with more howarditic-rich material associated with carbonaceous chondrite clasts and relatively higher OH and H concentrations (e.g., [1], [2], [3]). In general, these other two regions are also associated with thick flow features within the crater, while the HED-like area does not show such prominent flows. Hence, these darker regions seem to display post-impact material inflow of the weathered howarditic surface regolith. We conclude that the Marcia impactor likely struck through the howarditic regolith and hit the eucritic crust underneath. Depicting this HED-like signature globally, it resides mostly in the Rheasilvia basin and ejecta blanket, as well as in very young crater ejecta in the equatorial region, consistent with it being a signature of fresh basaltic crust. [1] M. C. De Sanctis et al. (2012b) The Astrophysical Journal Letters, 758:L36 (5pp) [2] T. McCord et al

  11. Cryptic photosynthesis, Extrasolar planetary oxygen without a surface biological signature

    CERN Document Server

    Cockell, C S; Raven, J A

    2008-01-01

    On the Earth, photosynthetic organisms are responsible for the production of nearly all of the oxygen in the atmosphere. On the land, vegetation reflects in the visible, leading to a red edge which has been proposed as a biosignature for life on extrasolar planets. However, in many regions of the Earth, and particularly where surface conditions are extreme, for example in hot and cold deserts, photosynthetic organisms can be driven into and under substrates where light is still sufficient for photosynthesis. These communities exhibit no detectable surface spectral signature. The same is true of the assemblages of photosynthetic organisms at more than a few meters depth in water bodies. These communities are widespread and dominate local photosynthetic productivity. We review known cryptic photosynthetic communities and their productivity. We use a radiative transfer model to link geomicrobiology with observational astronomy and calculate the disk-averaged spectra and identify detectable features that would re...

  12. Spectral signatures of x((5)) processes in four-wave mixing of homogeneously broadened excitons

    DEFF Research Database (Denmark)

    Langbein, W.; Meier, T.; Koch, S.W.;

    2001-01-01

    The influence of fifth-order coherences on the spectrally resolved four-wave mixing response of predominantly homogeneously broadened quasi-two-dimensional excitons is studied. Fifth-order signatures are discussed as a function of spectral position and excitation polarization. An exciton-biexcito...... of one- and two-exciton resonances up to the fifth order in the optical field.......The influence of fifth-order coherences on the spectrally resolved four-wave mixing response of predominantly homogeneously broadened quasi-two-dimensional excitons is studied. Fifth-order signatures are discussed as a function of spectral position and excitation polarization. An exciton...

  13. Spectral Representation Analysis of Non Contact Acousto Thermal Signature Data (Preprint)

    Science.gov (United States)

    2017-07-07

    the acoustic waves are absorbed into the material and converted to heat through the diffusion of transverse thermal currents, inter-crystalline...from Non-contact acousto-thermal signature (NCATS) experiments are considered. Spectral representation models are developed for general conductive...experiments are considered. Spectral representation models are developed for general conductive cooling physics. These models are subsequently used to

  14. Exact Spectral Dimension of the Random Surface

    CERN Document Server

    Goncharenko, Igor

    2009-01-01

    We propose a new method of the analytical computation of the spectral dimension which is based on the equivalence of the random walk and the q-state Potts model with non-zero magnetic field in the limit $q\\to 0$. Calculating the critical exponent of the magnetization of this model on the dynamically triangulated random surface by means of a matrix model technique we obtain that the spectral dimension of this surface is equal to two.

  15. Snapshots of Proton Accommodation at a Microscopic Water Surface: Understanding the Vibrational Spectral Signatures of the Charge Defect in Cryogenically Cooled H+(H2O)n=2 – 28 Clusters

    Energy Technology Data Exchange (ETDEWEB)

    Fournier, Joseph A.; Wolke, Conrad T.; Johnson, Mark A.; Odbadrakh, Tuguldur T.; Jordan, Kenneth D.; Kathmann, Shawn M.; Xantheas, Sotiris S.

    2015-07-09

    In this Article, we review the role of gas-phase, size-selected protonated water clusters, H+(H2O)n, in the analysis of the microscopic mechanics responsible for the behavior of the excess proton in bulk water. We extend upon previous studies of the smaller, two-dimensional sheet-like structures to larger (n≥10) assemblies with three-dimensional cage morphologies which better mimic the bulk environment. Indeed, clusters in which a complete second solvation shell forms around a surface-embedded hydronium ion yield vibrational spectra where the signatures of the proton defect display strikingly similar positions and breadth to those observed in dilute acids. We investigate effects of the local structure and intermolecular interactions on the large red shifts observed in the proton vibrational signature upon cluster growth using various theoretical methods. We show that, in addition to sizeable anharmonic couplings, the position of the excess proton vibration can be traced to large increases in the electric field exerted on the embedded hydronium ion upon formation of the first and second solvation shells. MAJ acknowledges support from the U.S. Department of Energy under Grant No. DE-FG02- 06ER15800 as well as the facilities and staff of the Yale University Faculty of Arts and Sciences High Performance Computing Center, and by the National Science Foundation under Grant No. CNS 08-21132 that partially funded acquisition of the facilities. SMK and SSX acknowledge support from the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences. Pacific Northwest National Laboratory (PNNL) is a multiprogram national laboratory operated for DOE by Battelle. This research used resources of the National Energy Research Scientific Computing Center, which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.

  16. A Real-Time Infrared Ultra-Spectral Signature Classification Method via Spatial Pyramid Matching.

    Science.gov (United States)

    Mei, Xiaoguang; Ma, Yong; Li, Chang; Fan, Fan; Huang, Jun; Ma, Jiayi

    2015-07-03

    The state-of-the-art ultra-spectral sensor technology brings new hope for high precision applications due to its high spectral resolution. However, it also comes with new challenges, such as the high data dimension and noise problems. In this paper, we propose a real-time method for infrared ultra-spectral signature classification via spatial pyramid matching (SPM), which includes two aspects. First, we introduce an infrared ultra-spectral signature similarity measure method via SPM, which is the foundation of the matching-based classification method. Second, we propose the classification method with reference spectral libraries, which utilizes the SPM-based similarity for the real-time infrared ultra-spectral signature classification with robustness performance. Specifically, instead of matching with each spectrum in the spectral library, our method is based on feature matching, which includes a feature library-generating phase. We calculate the SPM-based similarity between the feature of the spectrum and that of each spectrum of the reference feature library, then take the class index of the corresponding spectrum having the maximum similarity as the final result. Experimental comparisons on two publicly-available datasets demonstrate that the proposed method effectively improves the real-time classification performance and robustness to noise.

  17. A Real-Time Infrared Ultra-Spectral Signature Classification Method via Spatial Pyramid Matching

    Directory of Open Access Journals (Sweden)

    Xiaoguang Mei

    2015-07-01

    Full Text Available The state-of-the-art ultra-spectral sensor technology brings new hope for high precision applications due to its high spectral resolution. However, it also comes with new challenges, such as the high data dimension and noise problems. In this paper, we propose a real-time method for infrared ultra-spectral signature classification via spatial pyramid matching (SPM, which includes two aspects. First, we introduce an infrared ultra-spectral signature similarity measure method via SPM, which is the foundation of the matching-based classification method. Second, we propose the classification method with reference spectral libraries, which utilizes the SPM-based similarity for the real-time infrared ultra-spectral signature classification with robustness performance. Specifically, instead of matching with each spectrum in the spectral library, our method is based on feature matching, which includes a feature library-generating phase. We calculate the SPM-based similarity between the feature of the spectrum and that of each spectrum of the reference feature library, then take the class index of the corresponding spectrum having the maximum similarity as the final result. Experimental comparisons on two publicly-available datasets demonstrate that the proposed method effectively improves the real-time classification performance and robustness to noise.

  18. Signature of Wave Chaos in Spectral Characteristics of Microcavity Lasers

    CERN Document Server

    Sunada, Satoshi; Fukushima, Takehiro; Harayama, Takahisa

    2016-01-01

    We report the spectral characteristics of fully chaotic and non-chaotic microcavity lasers under continuous-wave operating conditions. It is found that fully chaotic microcavity lasers operate in single mode, whereas non-chaotic microcavity lasers operate in multimode. The suppression of multimode lasing for fully chaotic microcavity lasers is explained by large spatial overlaps of the resonance wave functions that spread throughout the two-dimensional cavity due to the ergodicity of chaotic ray orbits.

  19. Spectral signatures of polar stratospheric clouds and sulfate aerosol

    Energy Technology Data Exchange (ETDEWEB)

    Massie, S.T.; Bailey, P.L.; Gille, J.C. [National Center for Atmospheric Research, Boulder, CO (United States); Lee, E.C. [Princeton Univ., NJ (United States); Mergenthaler, J.L.; Roche, A.E.; Kumer, J.B. [Lockheed Palo Alto Research Lab., CA (United States); Fishbein, E.F.; Waters, J.W. [California Institute of Technology, Pasadena, CA (United States); Lahoz, W.A. [Univ. of Reading (United Kingdom)

    1994-10-15

    Multiwavelength observations of Antarctic and midlatitude aerosol by the Cryogenic Limb Array Etalon Spectrometer (CLAES) experiment on the Upper Atmosphere Research Satellite are used to demonstrate a technique that identifies the location of polar stratospheric clouds. The technique discussed uses the normalized area of the triangle formed by the aerosol extinctions at 925, 1257, and 1605 cm{sup {minus}1} (10.8, 8.0, and 6.2 {mu}m) to derive a spectral aerosol measure M of the aerosol spectrum. Mie calculations for spherical particles and T-matrix calculations for spheroidal particles are used to generate theoretical spectral extinction curves for sulfate and polar stratospheric cloud particles. The values of the spectral aerosol measure M for the sulfate and polar stratospheric cloud particles are shown to be different. Aerosol extinction data, corresponding to temperatures between 180 and 220 K at a pressure of 46 hPa (near 21-km altitude) for 18 August 1992, are used to demonstrate the technique. Thermodynamic calculations, based upon frost-point calculation and laboratory phase-equilibrium studies of nitric acid trihydrate, are used to predict the location of nitric acid trihydrate cloud particles. 47 refs., 22 figs., 3 tabs.

  20. Spectral induced polarization signatures of abiotic FeS precipitation

    Energy Technology Data Exchange (ETDEWEB)

    Ntarlagiannis, D.; Doherty, R.; Williams, K. H.

    2010-01-15

    In recent years, geophysical methods have been shown to be sensitive to microbial induced mineralization processes. The spectral induced polarization (SIP) method appears to be very promising for monitoring mineralization and microbial processes. With this work, we study the links of mineralization and SIP signals, in the absence of microbial activity. We recorded the SIP response during abiotic FeS precipitation. We show that the SIP signals are diagnostic of FeS mineralization and can be differentiated from SIP signals from bio-mineralization processes. More specifically the imaginary conductivity shows almost linear dependence on the amount of FeS precipitating out of solution, above the threshold value 0.006 gr under our experimental conditions. This research has direct implications for the use of the SIP method as a monitoring, and decision making, tool for sustainable remediation of metals in contaminated soils and groundwater.

  1. Spectral reflectance of SNC meteorites: Relationships to Martian surface composition

    Science.gov (United States)

    Mcfadden, L. A.

    1987-01-01

    The spectral signatures of each of the Shergottite-Nakhlite-Chassignite (SNC) meteorite types measured to date are unique among extraterrestrial materials. Reflectance spectra of dark regions of Mars show evidence of basaltic composition. Analytic analysis of absorption band positions and widths in reflectance spectra of SNC meteorites will permit comparisons with spectra from approximately 600 km sized regions for which high-quality, near-IR spectra are available. Multi-spectral mapping data from orbital spacecraft is expected to provide the necessary spectra to determine basaltic compositions of smaller regions on Mars provided fresh, unaltered basalts can be observed or the effects of Martian weathering can be understood and removed from the spectra. With modeling of spectral weathering and mixing of SNC meteoritic assemblages it should be possible with the Mars Observer data to test for the presence of SNC analogs on the Martian surface. Before the relationship between the basaltic composition of units on Mars and the SNC meteorites can be addressed, it is necessary to analyze the absorption band parameters of the SNC reflectance spectra and to acquire high resolution spectral data on smaller regions of the Martian surface.

  2. Studies on Ammonia Spectral Signatures Relevant to Jupiter's Clouds

    Science.gov (United States)

    Oza, A. U.; Marschall, J.; Wong, M. H.; Kalogerakis, K. S.

    2006-12-01

    Observational evidence and thermochemical models indicate an abundance of ammonia ice clouds in Jupiter's atmosphere. However, spectrally identifiable ammonia ice clouds are found covering less than 1% of Jupiter's atmosphere, notably in turbulent areas [1,2]. Current literature suggests two possible explanations: coating by a hydrocarbon haze and/or photochemical processing ("tanning")[2,3]. We are pursuing a research program investigating the above hypotheses. In the experiments, thin films of ammonia ices are deposited in a cryogenic apparatus, coated with hydrocarbons, and characterized by infrared spectroscopy. The ice films can be irradiated by ultraviolet light to study their photochemistry. The spectroscopic measurements aim to identify the processes that control the optical properties of the ice mixtures and quantify their dependence on the identity of the coating, the temperature, and the ice composition. We have observed a consistent suppression of the ammonia absorption feature at 3 μm with coverage by thin layers of hydrocarbons. Modeling calculations of the multi-layer thin films assist in the interpretation of the experimental results and reveal the role of optical interference in masking the aforementioned ammonia spectral feature. The implications of these results for Jupiter's atmosphere will be discussed. Funding from the NSF Planetary Astronomy Program under grant AST-0206270 and from the NASA Outer Planets Research Program under grant NNG06GF37G is gratefully acknowledged. The participation of Anand Oza (Princeton University) was made possible by the NSF Research Experiences for Undergraduates Program under grant PHY-0353745. 1. S. K. Atreya, A.-S. Wong, K. H. Baines, M. H. Wong, T. C. Owen, Planet. Space Science 53, 498 (2005). 2. K. H. Baines, R. W. Carlson, and L. W. Kamp, Icarus 159, 74 (2002). 3. A.-S. Wong, Y. L. Yung, and A. J. Friedson, Geophys. Res. Lett. 30, 1447 (2003).

  3. SSME Condition Monitoring Using Neural Networks and Plume Spectral Signatures

    Science.gov (United States)

    Hopkins, Randall; Benzing, Daniel

    1996-01-01

    For a variety of reasons, condition monitoring of the Space Shuttle Main Engine (SSME) has become an important concern for both ground tests and in-flight operation. The complexities of the SSME suggest that active, real-time condition monitoring should be performed to avoid large-scale or catastrophic failure of the engine. In 1986, the SSME became the subject of a plume emission spectroscopy project at NASA's Marshall Space Flight Center (MSFC). Since then, plume emission spectroscopy has recorded many nominal tests and the qualitative spectral features of the SSME plume are now well established. Significant discoveries made with both wide-band and narrow-band plume emission spectroscopy systems led MSFC to develop the Optical Plume Anomaly Detection (OPAD) system. The OPAD system is designed to provide condition monitoring of the SSME during ground-level testing. The operational health of the engine is achieved through the acquisition of spectrally resolved plume emissions and the subsequent identification of abnormal emission levels in the plume indicative of engine erosion or component failure. Eventually, OPAD, or a derivative of the technology, could find its way on to an actual space vehicle and provide in-flight engine condition monitoring. This technology step, however, will require miniaturized hardware capable of processing plume spectral data in real-time. An objective of OPAD condition monitoring is to determine how much of an element is present in the SSME plume. The basic premise is that by knowing the element and its concentration, this could be related back to the health of components within the engine. For example, an abnormal amount of silver in the plume might signify increased wear or deterioration of a particular bearing in the engine. Once an anomaly is identified, the engine could be shut down before catastrophic failure occurs. Currently, element concentrations in the plume are determined iteratively with the help of a non-linear computer

  4. Spectral signature of ultraviolet solar irradiance in Zacatecas

    Energy Technology Data Exchange (ETDEWEB)

    Pinedo V, J. L; Mireles G, F; Rios M, C; Quirino T, L. L; Davila R, J. I [Universidad Autonoma de Zacatecas, Zacatecas, Zacatecas (Mexico)

    2006-10-15

    This study presents an analysis of the global ultraviolet spectral irradiance (290-400 nm) registered in Zacatecas, a city near the Tropic of Cancer, located at 2500 m above sea level, latitude of 22 degrees N and longitude of 102 degrees W. The spectra have been measured using a Bentham radiometer with a 0.5 nm step in wavelength. The measurements show relatively high levels of ultraviolet irradiance (UV), which may be characteristic of areas close to the Tropic of Cancer. Faced with an increase of the incidence of skin cancer among the population of Zacatecas, these measurements highlight that a damage prevention plan is required. [Spanish] En este trabajo se presenta un analisis de la radiacion espectral global ultravioleta (290-400 nm) registrada en Zacatecas, una ciudad vecina al tropico de cancer, situada a 2500 m sobre el nivel del mar, latitud de 22 grados N y longitud de 102 grados O. Los espectros correspondientes han sido medidos mediante un espectroradiometro Bentham con un paso de 0.5 nm de longitud de onda. Las mediciones muestran niveles de radiacion ultravioleta (UV) relativamente elevados, que pueden ser caracteristicos de las zonas vecinas al tropico de cancer. Frente al aumento de incidencia de cancer en la piel en la poblacion del estado de Zacatecas, estas mediciones ponen en relieve la necesidad de formular un plan preventivo de danos.

  5. Spectral emissivity of surface blackbody calibrators

    DEFF Research Database (Denmark)

    Clausen, Sønnik

    2007-01-01

    The normal spectral emissivity of commercial infrared calibrators is compared with measurements of anodized aluminum samples and grooved aluminum surfaces coated with Pyromark. Measurements performed by FTIR spectroscopy in the wavelength interval from 2 to 20 mu m and at temperatures between 5...... in emissivity using similar materials can be reduced to 0.5-1% by optimizing the coating process and the surface geometry. Results are discussed and an equation for calculation of the equivalent blackbody surface temperature from FTIR spectra is presented, including reflected ambient radiation. It is in most...... cases necessary to correct temperature calibration results for calibrators calibrated at 8-14 mu m to obtain absolute accuracies of 0.1-1 degrees C in other spectral regions depending on the temperature. Uncertainties are discussed and equations are given for the correction of measured radiation...

  6. Spectral signatures of photosynthesis II: coevolution with other stars and the atmosphere on extrasolar worlds

    CERN Document Server

    Kiang, N Y; Tinetti, G; Blankenship, R E; Cohen, M; Siefert, J; Crisp, D; Meadows, V S; Kiang, Nancy Y.; Segura, Antigona; Tinetti, Giovanna; Blankenship, Robert E.; Cohen, Martin; Siefert, Janet; Crisp, David; Meadows, Victoria S.

    2007-01-01

    As photosynthesis on Earth produces the primary signatures of life that can be detected astronomically at the global scale, a strong focus of the search for extrasolar life will be photosynthesis, particularly photosynthesis that has evolved with a different parent star. We take planetary atmospheric compositions simulated by Segura, et al. (2003, 2005) for Earth-like planets around observed F2V and K2V stars, modeled M1V and M5V stars, and around the active M4.5V star AD Leo; our scenarios use Earth's atmospheric composition as well as very low O2 content in case anoxygenic photosynthesis dominates. We calculate the incident spectral photon flux densities at the surface of the planet and under water. We identify bands of available photosynthetically relevant radiation and find that photosynthetic pigments on planets around F2V stars may peak in absorbance in the blue, K2V in the red-orange, and M stars in the NIR, in bands at 0.93-1.1 microns, 1.1-1.4 microns, 1.5-1.8 microns, and 1.8-2.5 microns. In additio...

  7. Analytical chemistry, multidimensional spectral signatures, and the future of coherent multidimensional spectroscopy

    Science.gov (United States)

    Wright, John C.

    2016-10-01

    Spectroscopy is a dominant measurement methodology because it resolves molecular level details over a wide concentration range. Its limitations, however, become challenged when applied to complex materials. Coherent multidimensional spectroscopy (CMDS) is the optical analogue of multidimensional NMR and like NMR, its multidimensionality promises to increase the spectral selectivity of vibrational and electronic spectroscopy. This article explores whether this promise can make CMDS a dominant spectroscopic method throughout the sciences. In order for CMDS to become a dominant methodology, it must create multidimensional spectral fingerprints that provide the selectivity required for probing complex samples. Pump-CMDS probe methods separate the pump's measurement of dynamics from a multidimensional and selective probe. Fully coherent CMDS methods are ideal multidimensional probes because they avoid relaxation effects, spectrally isolate the output signals, and provide unique and invariant spectral signatures using any combination of vibrational and electronic quantum states.

  8. Spectral signatures for the classification of microbial species using Raman spectra.

    Science.gov (United States)

    Webb-Robertson, Bobbie-Jo M; Bailey, Vanessa L; Fansler, Sarah J; Wilkins, Michael J; Hess, Nancy J

    2012-08-01

    In general, classification-based methods based on confocal Raman microscopy are focused on targeted studies under which the spectral libraries are collected under controlled instrument parameters, which facilitate analyses via standard multivariate data analysis methods and cross-validation. We develop and compare approaches to transform spectra collected at different spectral ranges and varying levels of resolution into a single lower-dimension spectral signature library. This will result in a more robust analysis method able to accommodate spectra accumulated at different times and conditions. We demonstrate these approaches on a relevant test case; the identification of microbial species from a natural environment. The training data were based on samples prepared for three unique species collected at two time points and the test data consisted of blinded unknowns prepared and analyzed at a later date with different instrument parameters. The results indicate that using reduced dimension representations of the spectral signatures improves classification accuracy over basic alignment protocols. In particular, utilizing the microbial species partial least squares discriminant analysis classifier on the blinded samples based on alignment achieved ~78 % accuracy, while both binning and peak selection approaches yielded 100 % accuracy.

  9. Spectral properties and conformal type of surfaces

    Directory of Open Access Journals (Sweden)

    PHILIPPE CASTILLON

    2002-12-01

    Full Text Available In this short note, we announce a result relating the geometry of a riemannian surface to the positivity of some operators on this surface (the operators considered here are of the form surface Laplacian plus a scalar multiple of the curvature function. In particular we obtain a theorem "à la Huber'': under a spectral hypothesis we prove that the surface is conformally equivalent to a Riemann surface with a finite number of points removed. This problem has its origin in the study of stable minimal surfaces.Nesta comunicação, anunciamos um resultado que relaciona a geometria de uma superfície riemanniana com a positividade de certos operadores na superfície (os operadores considerados têm forma "Laplaciano mais um múltiplo da curvatura''. Em particular, obtemos um teorema "à la Huber'': usando uma condição espectral, provamos que a superfície é conformemente equivalente a uma superfície de Riemann menos um número finito de pontos. Este problema tem origem no estudo das superfícies mínimas estáveis.

  10. Sea Surface Salinity signature of tropical Atlantic interannual modes

    Science.gov (United States)

    Awo, Mesmin; Alory, Gael; Da-Allada, Casimir; Jouanno, Julien; Delcroix, Thierry; Baloitcha, Ezinvi

    2017-04-01

    Interannual climate variability in the tropical Atlantic is dominated by two internal modes: an equatorial and a meridional mode. The equatorial mode is partly responsible for sea surface temperature (SST) anomalies observed in boreal summer in the Gulf of Guinea. The meridional mode peaks in boreal spring as an inter-hemispheric SST fluctuation. Previous studies show that these modes affect the migration of the inter tropical convergence zone which drives regional precipitation. In this study, we extracted the Sea Surface Salinity (SSS) signature of these modes from in situ data. The results indicate strong SSS anomalies in the equatorial, north west and south east tropical Atlantic related to the equatorial mode. Moreover, the results also indicate the existence of a meridional SSS dipole in the equatorial region, strong SSS anomalies in north and south tropical Atlantic and in runoff regions, related to the meridional mode. Using a mixed-layer salt budget in a realistic model, we investigated the oceanic and/or atmospheric processes responsible for this signature: For the equatorial mode, both fresh water flux and horizontal advection explain the observed signature in the north equatorial region, but in the south equatorial region, the signature is explained by the combined contribution of total (horizontal and vertical) advection and vertical diffusion. For the meridional mode, changes in fresh water flux explain the observed equatorial dipole while the signature in runoff regions is explained by the total advection. In the north west and south east tropical Atlantic, only horizontal advection is important for explaining the signature of these two modes.

  11. SURFACE ALBEDO AND SPECTRAL VARIABILITY OF CERES

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jian-Yang; Reddy, Vishnu; Corre, Lucille Le; Sykes, Mark V.; Prettyman, Thomas H. [Planetary Science Institute, 1700 E. Ft. Lowell Road, Suite 106, Tucson, AZ 85719 (United States); Nathues, Andreas; Hoffmann, Martin; Schaefer, Michael [Max Planck Institute for Solar System Research, Göttingen (Germany); Izawa, Matthew R. M.; Cloutis, Edward A. [University of Winnipeg, Winnipeg, Manitoba (Canada); Carsenty, Uri; Jaumann, Ralf; Krohn, Katrin; Mottola, Stefano; Schröder, Stefan E. [German Aerospace Center (DLR), Institute of Planetary Research, Berlin (Germany); Castillo-Rogez, Julie C. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Schenk, Paul [Lunar and Planetary Institute, Houston, TX 77058 (United States); Williams, David A. [School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287 (United States); Smith, David E. [Solar System Exploration Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Zuber, Maria T. [Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); and others

    2016-02-01

    Previous observations suggested that Ceres has active, but possibly sporadic, water outgassing as well as possibly varying spectral characteristics over a timescale of months. We used all available data of Ceres collected in the past three decades from the ground and the Hubble Space Telescope, as well as the newly acquired images by the Dawn  Framing Camera, to search for spectral and albedo variability on Ceres, on both a global scale and in local regions, particularly the bright spots inside the Occator crater, over timescales of a few months to decades. Our analysis has placed an upper limit on the possible temporal albedo variation on Ceres. Sporadic water vapor venting, or any possibly ongoing activity on Ceres, is not significant enough to change the albedo or the area of the bright features in the Occator crater by >15%, or the global albedo by >3% over the various timescales that we searched. Recently reported spectral slope variations can be explained by changing Sun–Ceres–Earth geometry. The active area on Ceres is less than 1 km{sup 2}, too small to cause global albedo and spectral variations detectable in our data. Impact ejecta due to impacting projectiles of tens of meters in size like those known to cause observable changes to the surface albedo on Asteroid Scheila cannot cause detectable albedo change on Ceres due to its relatively large size and strong gravity. The water vapor activity on Ceres is independent of Ceres’ heliocentric distance, ruling out the possibility of the comet-like sublimation process as a possible mechanism driving the activity.

  12. Biomaterial surface proteomic signature determines interaction with epithelial cells.

    Science.gov (United States)

    Abdallah, Mohamed-Nur; Tran, Simon D; Abughanam, Ghada; Laurenti, Marco; Zuanazzi, David; Mezour, Mohamed A; Xiao, Yizhi; Cerruti, Marta; Siqueira, Walter L; Tamimi, Faleh

    2017-03-01

    Cells interact with biomaterials indirectly through extracellular matrix (ECM) proteins adsorbed onto their surface. Accordingly, it could be hypothesized that the surface proteomic signature of a biomaterial might determine its interaction with cells. Here, we present a surface proteomic approach to test this hypothesis in the specific case of biomaterial-epithelial cell interactions. In particular, we determined the surface proteomic signature of different biomaterials exposed to the ECM of epithelial cells (basal lamina). We revealed that the biomaterial surface chemistry determines the surface proteomic profile, and subsequently the interaction with epithelial cells. In addition, we found that biomaterials with surface chemistries closer to that of percutaneous tissues, such as aminated PMMA and aminated PDLLA, promoted higher selective adsorption of key basal lamina proteins (laminins, nidogen-1) and subsequently improved their interactions with epithelial cells. These findings suggest that mimicking the surface chemistry of natural percutaneous tissues can improve biomaterial-epithelial integration, and thus provide a rationale for the design of improved biomaterial surfaces for skin regeneration and percutaneous medical devices.

  13. Study of air pollutant signatures for remote sensing. [of the spectral reflectivity of leaves

    Science.gov (United States)

    Nowak, W. B.

    1974-01-01

    Experimental results are presented for a possible new, indirect signature for air pollutants: the spectral reflectivity of plant leaves. Sub-visual changes (up to 160%) in the spectral reflectivity of bean and tobacco leaves were observed over the range 475nm to 750nm in response to SO2 exposures such as 2ppm/4hrs or 4ppm/16hrs, or to O3 exposures such as 90pphm/21hrs or 7.5pphm/292hrs. Such changes might be observed from a satellite using either laser or sunlight as the illumination source. Inasmuch as the plants appear to become acclimated to some of these exposure doses, environmental changes may be most important for this type of plant-response.

  14. 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.

  15. 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.

  16. [Investigation of quantitative detection of water quality using spectral fluorescence signature].

    Science.gov (United States)

    He, Jun-hua; Cheng, Yong-jin; Han, Yan-ling; Zhang, Hao; Yang, Tao

    2008-08-01

    A method of spectral analysis, which can simultaneously detect dissolved organic matter (DOM) and chlorophyll a (Chl-a) in natural water, was developed in the present paper with the intention of monitoring water quality fast and quantitatively. Firstly, the total luminescence spectra (TLS) of water sample from East Lake in Wuhan city were measured by the use of laser (532 nm) induced fluorescence (LIF). There were obvious peaks of relative intensity at the wavelength value of 580, 651 and 687 nm in the TLS of the sample, which correspond respectively to spectra of DOM, and the Raman scattering of water and Chl-a in the water. Then the spectral fluorescence signature (SFS) technique was adopted to analyze and distinguish spectral characteristics of DOM and Chl-a in natural water. The calibration curves and function expressions, which indicate the relation between the normalized fluorescence intensities of DOM and Chl-a in water and their concentrations, were obtained respectively under the condition of low concentration( 40 mg x L(-1)), the Raman scattering signal is totally absorbed by the molecules of humic acid being on the ground state, so the normalization technique can not be adopted. However the function expression between the concentration of the solution with humic acid and its relative fluorescence peak intensity can be acquired directly with the aid of experiment of fluorescence spectrum. It is concluded that although the expression is non-linearity as a whole, there is a excellent linear relation between the fluorescence intensity and concentration of DOM when the concentration is less than 200 mg x L(-1). The method of measurement based on spectral fluorescence signature technique and the calibration curves gained will have prospects of broad application. It can recognize fast what pollutants are and detect quantitatively their contents in water. It is realizable to monitor the quality of natural water with real time, dynamics and inlarge area.

  17. Reflectance Spectral Characteristics of Lunar Surface Materials

    Institute of Scientific and Technical Information of China (English)

    Yong-Liao Zou; Jian-Zhong Liu; Jian-Jun Liu; Tao Xu

    2004-01-01

    Based on a comprehensive analysis of the mineral composition of major lunar rocks (highland anorthosite, lunar mare basalt and KREEP rock), we investigate the reflectance spectral characteristics of the lunar rock-forming minerals, including feldspar, pyroxene and olivine. The affecting factors, the variation of the intensity of solar radiation with wavelength and the reflectance spectra of the lunar rocks are studied. We also calculate the reflectivity of lunar mare basalt and highland anorthosite at 300 nm, 415 nm, 750 nm, 900 nm, 950 nm and 1000 nm.It is considered that the difference in composition between lunar mare basalt and highland anorthosite is so large that separate analyses are needed in the study of the reflectivity of lunar surface materials in the two regions covered by mare basalt and highland anorthosite, and especially in the region with high Th contents, which may be the KREEP-distributed region.

  18. Satellite propulsion spectral signature detection and analysis through Hall effect thruster plume and atmospheric modeling

    Science.gov (United States)

    Wheeler, Pamela; Cobb, Richard; Hartsfield, Carl; Prince, Benjamin

    2016-09-01

    Space Situational Awareness (SSA) is of utmost importance in today's congested and contested space environment. Satellites must perform orbital corrections for station keeping, devices like high efficiency electric propulsion systems such as a Hall effect thrusters (HETs) to accomplish this are on the rise. The health of this system is extremely important to ensure the satellite can maintain proper position and perform its intended mission. Electron temperature is a commonly used diagnostic to determine the efficiency of a hall thruster. Recent papers have coordinated near infrared (NIR) spectral measurements of emission lines in xenon and krypton to electron temperature measurements. Ground based observations of these spectral lines could allow the health of the thruster to be determined while the satellite is in operation. Another issue worth considering is the availability of SSA assets for ground-based observations. The current SSA architecture is limited and task saturated. If smaller telescopes, like those at universities, could successfully detect these signatures they could augment data collection for the SSA network. To facilitate this, precise atmospheric modeling must be used to pull out the signature. Within the atmosphere, the NIR has a higher transmission ratio and typical HET propellants are approximately 3x the intensity in the NIR versus the visible spectrum making it ideal for ground based observations. The proposed research will focus on developing a model to determine xenon and krypton signatures through the atmosphere and estimate the efficacy through ground-based observations. The model will take power modes, orbit geometries, and satellite altitudes into consideration and be correlated with lab and field observations.

  19. Reference spectral signature selection using density-based cluster for automatic oil spill detection in hyperspectral images.

    Science.gov (United States)

    Liu, Delian; Zhang, Jianqi; Wang, Xiaorui

    2016-04-04

    Reference spectral signature selection is a fundamental work for automatic oil spill detection. To address this issue, a new approach is proposed here, which employs the density-based cluster to select a specific spectral signature from a hyperspectral image. This paper first introduces the framework of oil spill detection from hyperspectral images, indicating that detecting oil spill requires a reference spectral signature of oil spill, parameters of background, and a target detection algorithm. Based on the framework, we give the new reference spectral signature selection approach in details. Then, we demonstrate the estimation of background parameters according to the reflectance of seawater in the infrared bands. Next, the conventional adaptive cosine estimator (ACE) algorithm is employed to achieve oil spill detection. Finally, the proposed approach is tested via several practical hyperspectral images that are collected during the Horizon Deep water oil spill. The experimental results show that this new approach can automatically select the reference spectral signature of oil spills from hyperspectral images and has high detection performance.

  20. Spectral Signatures of Photosynthesis. II. Coevolution with Other Stars And The Atmosphere on Extrasolar Worlds

    Science.gov (United States)

    Kiang, Nancy Y.; Segura, Antígona; Tinetti, Giovanna; Govindjee; Blankenship, Robert E.; Cohen, Martin; Siefert, Janet; Crisp, David; Meadows, Victoria S.

    2007-02-01

    As photosynthesis on Earth produces the primary signatures of life that can be detected astronomically at the global scale, a strong focus of the search for extrasolar life will be photosynthesis, particularly photosynthesis that has evolved with a different parent star. We take previously simulated planetary atmospheric compositions for Earth-like planets around observed F2V and K2V, modeled M1V and M5V stars, and around the active M4.5V star AD Leo; our scenarios use Earth's atmospheric composition as well as very low O2 content in case anoxygenic photosynthesis dominates. With a line-by-line radiative transfer model, we calculate the incident spectral photon flux densities at the surface of the planet and under water. We identify bands of available photosynthetically relevant radiation and find that photosynthetic pigments on planets around F2V stars may peak in absorbance in the blue, K2V in the red-orange, and M stars in the near-infrared, in bands at 0.93-1.1 μm, 1.1-1.4 μm, 1.5-1.8 μ m, and 1.8-2.5 μm. However, underwater organisms will be restricted to wavelengths shorter than 1.4 μm and more likely below 1.1 μm. M star planets without oxygenic photosynthesis will have photon fluxes above 1.6 μm curtailed by methane. Longer-wavelength, multi-photo-system series would reduce the quantum yield but could allow for oxygenic photosystems at longer wavelengths. A wavelength of 1.1 μm is a possible upper cutoff for electronic transiprotions versus only vibrational energy; however, this cutoff is not strict, since such energetics depend on molecular configuration. M star planets could be a half to a tenth as productive as Earth in the visible, but exceed Earth if useful photons extend to 1.1 μm for anoxygenic photosynthesis. Under water, organisms would still be able to survive ultraviolet flares from young M stars and acquire adequate light for growth. Key Words: Photosynthesis-Astrobiology - Photosynthetic pigments - Oxygenic photosynthesis - Anoxygenic

  1. Contrasting Spectral Signatures and Sensitivities of CPA-Lasing in a $\\cal PT$-Symmetric Periodic Structure

    CERN Document Server

    Ge, Li

    2016-01-01

    The CPA-laser is a coexisting state of coherent perfect absorption and lasing that was proposed in parity-time ($\\cal PT$) symmetric photonic systems. In this work we show that the spectral signature of a CPA-laser displayed by the singular value spectrum of the scattering matrix ($S$) can be orders of magnitude wider than that displayed by the eigenvalue spectrum of $S$. Since the former reflects how strongly light can be absorbed or amplified and the latter announces the spontaneous symmetry breaking of $S$, these contrasting spectral signatures indicate that near perfect absorption and extremely strong amplification can be achieved even in the $\\cal PT$-symmetric phase of $S$, which is known for and defined by its flux-conserving eigenstates. We also show that these contrasting spectral signatures are accompanied by strikingly different sensitivities to disorder and imperfection, suggesting that the eigenvalue spectrum is potentially suitable for sensing and the singular value spectrum for robust switching...

  2. 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

  3. 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.

  4. Spectral fluorescence signature techniques and absorption measurements for continuous monitoring of biofuel-producing microalgae cultures

    Science.gov (United States)

    Martín de la Cruz, M. C.; Gonzalez Vilas, L.; Yarovenko, N.; Spyrakos, E.; Torres Palenzuela, J. M.

    2013-08-01

    Biofuel production from microalgae can be both sustainable and economically viable. Particularly in the case of algal growth in wastewater an extra benefit is the removal or biotransformation of pollutants from these types of waters. A continuous monitoring system of the microalgae status and the concentration of different wastewater contaminants could be of great help in the biomass production and the water characterisation. In this study we present a system where spectral fluorescence signature (SFS) techniques are used along with absorption measurements to monitor microalgae cultures in wastewater and other mediums. This system aims to optimise the microalgae production for biofuel applications or other uses and was developed and tested in prototype indoor photo-bioreactors at the University of Vigo. SFS techniques were applied using the fluorescence analyser INSTAND-SCREENER developed by Laser Diagnostic Instruments AS. INSTAND-SCREENER permits wavelength scanning in two modes, one in UV and another in VIS. In parallel, it permits the on-line monitoring and rapid analysis of both water quality and phytoplankton status without prior treatment of the sample. Considering that different contaminants and microalgae features (density, status etc.) have different spectral signatures of fluorescence and absorption properties, it is possible to characterise them developing classification libraries. Several algorithms were used for the classification. The implementation of this system in an outdoor raceway reactor in a Spanish wastewater treatment plant is also discussed. This study was part of the Project EnerBioAlgae (http://www.enerbioalgae.com/), which was funded by the Interreg SUDOE and led by the University of Vigo.

  5. Spectral Radiative Properties of Two-Dimensional Rough Surfaces

    Science.gov (United States)

    Xuan, Yimin; Han, Yuge; Zhou, Yue

    2012-12-01

    Spectral radiative properties of two-dimensional rough surfaces are important for both academic research and practical applications. Besides material properties, surface structures have impact on the spectral radiative properties of rough surfaces. Based on the finite difference time domain algorithm, this paper studies the spectral energy propagation process on a two-dimensional rough surface and analyzes the effect of different factors such as the surface structure, angle, and polarization state of the incident wave on the spectral radiative properties of the two-dimensional rough surface. To quantitatively investigate the spatial distribution of energy reflected from the rough surface, the concept of the bidirectional reflectance distribution function is introduced. Correlation analysis between the reflectance and different impact factors is conducted to evaluate the influence degree. Comparison between the theoretical and experimental data is given to elucidate the accuracy of the computational code. This study is beneficial to optimizing the surface structures of optoelectronic devices such as solar cells.

  6. Detection and classification of salmonella serotypes using spectral signatures collected by fourier transform infrared (FT-IR) spectroscopy

    Science.gov (United States)

    Spectral signatures of Salmonella serotypes namely Salmonella Typhimurium, Salmonella Enteritidis, Salmonella Infantis, Salmonella Heidelberg and Salmonella Kentucky were collected using Fourier transform infrared spectroscopy (FT-IR). About 5-10 µL of Salmonella suspensions with concentrations of 1...

  7. Intrinsic chirality and prochirality at Air/R-(+)- and S-(-)-limonene interfaces: spectral signatures with interference chiral sum-frequency generation vibrational spectroscopy.

    Science.gov (United States)

    Fu, Li; Zhang, Yun; Wei, Zhe-Hao; Wang, Hong-Fei

    2014-09-01

    We report in this work detailed measurements of the chiral and achiral sum-frequency vibrational spectra in the C-H stretching vibration region (2800-3050 cm(-1)) of the air/liquid interfaces of R-(+)-limonene and S-(-)-limonene, using the recently developed high-resolution broadband sum-frequency generation vibrational spectroscopy (HR-BB-SFG-VS). The achiral SFG spectra of R-limonene and S-limonene, as well as the RS racemic mixture (50/50 equal amount mixture), show that the corresponding molecular groups of the R and S enantiomers are with the same interfacial orientations. The interference chiral SFG spectra of the limonene enantiomers exhibit a spectral signature from the chiral response of the Cα-H stretching mode, and a spectral signature from the prochiral response of the CH(2) asymmetric stretching mode, respectively. The chiral spectral feature of the Cα-H stretching mode changes sign from R-(+)-limonene to S-(-)-limonene surfaces, and disappears for the RS racemic mixture surface. While the prochiral spectral feature of the CH(2) asymmetric stretching mode is the same for R-(+)-limonene and S-(-)-limonene surfaces, and also surprisingly remains the same for the RS racemic mixture surface. Therefore, the structures of the R-(+)-limonene and the S-(-)-limonene at the liquid interfaces are nevertheless not mirror images to each other, even though the corresponding groups have the same tilt angle from the interfacial normal, i.e., the R-(+)-limonene and the S-(-)-limonene at the surface are diastereomeric instead of enantiomeric. These results provide detailed information in understanding the structure and chirality of molecular interfaces and demonstrate the sensitivity and potential of SFG-VS as a unique spectroscopic tool for chirality characterization and chiral recognition at the molecular interface.

  8. New Asia Dust Storm Detection Method Based on the Thermal Infrared Spectral Signature

    Directory of Open Access Journals (Sweden)

    Hui Xu

    2014-12-01

    Full Text Available As hyperspectral instruments can provide the detailed spectral information, a new spectral similarity method for detecting and differentiating dust from non-dust scenes using the Atmospheric Infrared Sounder (AIRS observations has been developed. The detection is based on a pre-defined Dust Spectral Similarity Index (DSSI, which was calculated from the accumulated brightness temperature differences between selected 16 AIRS observation channels, in the thermal infrared region of 800–1250 cm−1. It has been demonstrated that DSSI can effectively separate the dust from non-dust by elevating dust signals. For underlying surface covered with dust, the DSSI tends to show values close to 1.0. However, the values of DSSI for clear sky surfaces or clouds (ice and water are basically lower than those of dust, as their spectrums have significant differences with dust. To evaluate this new simple DSSI dust detection algorithm, several Asia dust events observed in northern China were analyzed, and the results agree favorably with those from the Moderate resolution Imaging Spectro radiometer (MODIS and Cloud Aerosol LiDAR with Orthogonal Polarization (CALIOP observations.

  9. Synthetic Absorption Lines for a Clumpy Medium: A Spectral Signature for Cloud Acceleration in AGN?

    Science.gov (United States)

    Waters, Tim; Proga, Daniel; Dannen, Randall; Kallman, Timothy R.

    2017-01-01

    There is increasing evidence that the highly ionized multiphase components of AGN disc winds may be due to thermal instability. The ions responsible for forming the observed X-ray absorption lines may only exist in relatively cool clumps that can be identified with the so-called warm absorbers. Here we calculate synthetic absorption lines for such warm absorbers from first principles by combining 2D hydrodynamic solutions of a two-phase medium with a dense grid of photoionization models to determine the detailed ionization structure of the gas. Our calculations reveal that cloud disruption, which leads to a highly complicated velocity field (i.e. a clumpy flow), will only mildly affect line shapes and strengths when the warm gas becomes highly mixed but not depleted. Prior to complete disruption, clouds that are optically thin to the driving UV resonance lines will cause absorption at an increasingly blueshifted line-of-sight velocity as they are accelerated. This behavior will imprint an identifiable signature on the line profile if warm absorbers are enshrouded in an even broader absorption line produced by a high column of intercloud gas. Interestingly, we show that it is possible to develop a spectral diagnostic for cloud acceleration by differencing the absorption components of a doublet line, a result that can be qualitatively understood using a simple partial covering model. Our calculations also permit us to comment on the spectral differences between cloud disruption and ionization changes driven by flux variability. Notably, cloud disruption offers another possibility for explaining absorption line variability.

  10. Synthetic absorption lines for a clumpy medium: a spectral signature for cloud acceleration in AGN?

    Science.gov (United States)

    Waters, Tim; Proga, Daniel; Dannen, Randall; Kallman, Timothy R.

    2017-05-01

    There is increasing evidence that the highly ionized multiphase components of AGN disc winds may be due to thermal instability. The ions responsible for forming the observed X-ray absorption lines may only exist in relatively cool clumps that can be identified with the so-called warm absorbers. Here we calculate synthetic absorption lines for such warm absorbers from first principles by combining 2D hydrodynamic solutions of a two-phase medium with a dense grid of photoionization models to determine the detailed ionization structure of the gas. Our calculations reveal that cloud disruption, which leads to a highly complicated velocity field (i.e. a clumpy flow), will only mildly affect line shapes and strengths when the warm gas becomes highly mixed but not depleted. Prior to complete disruption, clouds that are optically thin to the driving UV resonance lines will cause absorption at an increasingly blueshifted line-of-sight velocity as they are accelerated. This behaviour will imprint an identifiable signature on the line profile if warm absorbers are enshrouded in an even broader absorption line produced by a high column of intercloud gas. Interestingly, we show that it is possible to develop a spectral diagnostic for cloud acceleration by differencing the absorption components of a doublet line, a result that can be qualitatively understood using a simple partial covering model. Our calculations also permit us to comment on the spectral differences between cloud disruption and ionization changes driven by flux variability. Notably, cloud disruption offers another possibility for explaining absorption line variability.

  11. Synthetic absorption lines for a clumpy medium: a spectral signature for cloud acceleration in AGN?

    Science.gov (United States)

    Waters, Tim; Proga, Daniel; Dannen, Randall; Kallman, Timothy R.

    2017-01-01

    There is increasing evidence that the highly ionised multiphase components of AGN disc winds may be due to thermal instability. The ions responsible for forming the observed X-ray absorption lines may only exist in relatively cool clumps that can be identified with the so-called `warm absorbers'. Here we calculate synthetic absorption lines for such warm absorbers from first principles by combining 2D hydrodynamic solutions of a two-phase medium with a dense grid of photoionization models to determine the detailed ionization structure of the gas. Our calculations reveal that cloud disruption, which leads to a highly complicated velocity field (i.e. a clumpy flow), will only mildly affect line shapes and strengths when the warm gas becomes highly mixed but not depleted. Prior to complete disruption, clouds which are optically thin to the driving UV resonance lines will cause absorption at an increasingly blueshifted line of sight velocity as they are accelerated. This behavior will imprint an identifiable signature on the line profile if warm absorbers are enshrouded in an even broader absorption line produced by a high column of intercloud gas. Interestingly, we show that it is possible to develop a spectral diagnostic for cloud acceleration by differencing the absorption components of a doublet line, a result which can be qualitatively understood using a simple partial covering model. Our calculations also permit us to comment on the spectral differences between cloud disruption and ionization changes driven by flux variability. Notably, cloud disruption offers another possibility for explaining absorption line variability.

  12. Surface Albedo and Spectral Variability of Ceres

    CERN Document Server

    Li, Jian-Yang; Nathues, Andreas; Corre, Lucille Le; Izawa, Matthew R M; Clouts, Edward A; Sykes, Mark V; Carsenty, Uri; Castillo-Rogez, Julie C; Hoffmann, Martin; Jaumann, Ralf; Krohn, Katrin; Mottola, Stefano; Prettyman, Thomas H; Schaefer, Michael; Schenk, Paul; Schröder, Stefan E; Williams, David A; Smith, David E; Zuber, Maria T; Konopliv, Alexander S; Park, Ryan S; Raymond, Carol A; Russell, Christopher T

    2016-01-01

    Previous observations suggested that Ceres has active but possibly sporadic water outgassing, and possibly varying spectral characteristics in a time scale of months. We used all available data of Ceres collected in the past three decades from the ground and the Hubble Space Telescope, and the newly acquired images by Dawn Framing Camera to search for spectral and albedo variability on Ceres, in both a global scale and local regions, particularly the bright spots inside Occator crater, over time scales of a few months to decades. Our analysis has placed an upper limit on the possible temporal albedo variation on Ceres. Sporadic water vapor venting, or any possibly ongoing activity on Ceres, is not significant enough to change the albedo or the area of the bright features in Occator crater by >15%, or the global albedo by >3% over various time scales that we searched. Recently reported spectral slope variations can be explained by changing Sun-Ceres-Earth geometry. The active area on Ceres is less than 1 km$^2...

  13. Determination of single particle mass spectral signatures from light-duty vehicle emissions.

    Science.gov (United States)

    Sodeman, David A; Toner, Stephen M; Prather, Kimberly A

    2005-06-15

    In this study, 28 light-duty gasoline vehicles (LDV) were operated on a chassis dynamometer at the California Air Resources Board Haagen-Smit Facility in El Monte, CA. The mass spectra of individual particles emitted from these vehicles were measured using aerosol time-of-flight mass spectrometry (ATOFMS). A primary goal of this study involves determining representative size-resolved single particle mass spectral signatures that can be used in future ambient particulate matter source apportionment studies. Different cycles were used to simulate urban driving conditions including the federal testing procedure (FTP), unified cycle (UC), and the correction cycle (CC). The vehicles were selected to span a range of catalytic converter (three-way, oxidation, and no catalysts) and engine technologies (vehicles models from 1953 to 2003). Exhaust particles were sampled directly from a dilution and residence chamber system using particle sizing instruments and an ATOFMS equipped with an aerodynamic lens (UF-ATOFMS) analyzing particles between 50 and 300 nm. On the basis of chemical composition, 10 unique chemical types describe the majority of the particles with distinct size and temporal characteristics. In the ultrafine size range (between 50 and 100 nm), three elemental carbon (EC) particle types dominated, all showing distinct EC signatures combined with Ca, phosphate, sulfate, and a lower abundance of organic carbon (OC). The relative fraction of EC particle types decreased as particle size increased with OC particles becoming more prevalent above 100 nm. Depending on the vehicle and cycle, several distinct OC particle types produced distinct ion patterns, including substituted aromatic compounds and polycyclic aromatic hydrocarbons (PAH), coupled with other chemical species including ammonium, EC, nitrate, sulfate, phosphate, V, and Ca. The most likely source of the Ca and phosphate in the particles is attributed to the lubricating oil. Significant variability was

  14. Separation Surfaces in the Spectral TV Domain for Texture Decomposition

    Science.gov (United States)

    Horesh, Dikla; Gilboa, Guy

    2016-09-01

    In this paper we introduce a novel notion of separation surfaces for image decomposition. A surface is embedded in the spectral total-variation (TV) three dimensional domain and encodes a spatially-varying separation scale. The method allows good separation of textures with gradually varying pattern-size, pattern-contrast or illumination. The recently proposed total variation spectral framework is used to decompose the image into a continuum of textural scales. A desired texture, within a scale range, is found by fitting a surface to the local maximal responses in the spectral domain. A band above and below the surface, referred to as the \\textit{Texture Stratum}, defines for each pixel the adaptive scale-range of the texture. Based on the decomposition an application is proposed which can attenuate or enhance textures in the image in a very natural and visually convincing manner.

  15. Vibrational Spectral Signatures of Crystalline Cellulose Using High Resolution Broadband Sum Frequency Generation Vibrational Spectroscopy (HR-BB-SFG-VS)

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Libing; Lu, Zhou; Velarde Ruiz Esparza, Luis A.; Fu, Li; Pu, Yunqiao; Ding, Shi-You; Ragauskas, Art J.; Wang, Hongfei; Yang, Bin

    2015-03-03

    Here we reported the first sub-wavenumber high-resolution broadband sum frequency generation vibrational spectroscopy (HR-BB-SFG-VS) study on both the C-H and O-H region spectra of crystalline cellulose. HR-BB-SFG-VS has about 10 times better resolution than the conventional scanning SFG-VS and is known to be able to measure the intrinsic spectral lineshape and to resolve much more spectral details. With HR-BB-SFG-VS, we found that in cellulose from different sources, including Avicel and cellulose crystals isolated from algae Valonia (Iα) and tunicates (Iβ), the spectral signatures in the OH regions were unique for different allomorphs, i.e. Iα and Iβ, while the spectral signatures in the C-H regions varied in all samples examined. Even though the origin of the different behaviors of the crystalline cellulose in the O-H and C-H vibrational frequency regions is yet to be correlated to the structure of cellulose, these results provided new spectroscopic methods and opportunities to classify and understand the basic crystalline structure, as well as variations, in polymorphism of the crystalline cellulose structure.

  16. Spectral theory of infinite-area hyperbolic surfaces

    CERN Document Server

    Borthwick, David

    2016-01-01

    This text introduces geometric spectral theory in the context of infinite-area Riemann surfaces, providing a comprehensive account of the most recent developments in the field. For the second edition the context has been extended to general surfaces with hyperbolic ends, which provides a natural setting for development of the spectral theory while still keeping technical difficulties to a minimum. All of the material from the first edition is included and updated, and new sections have been added. Topics covered include an introduction to the geometry of hyperbolic surfaces, analysis of the resolvent of the Laplacian, scattering theory, resonances and scattering poles, the Selberg zeta function, the Poisson formula, distribution of resonances, the inverse scattering problem, Patterson-Sullivan theory, and the dynamical approach to the zeta function. The new sections cover the latest developments in the field, including the spectral gap, resonance asymptotics near the critical line, and sharp geometric constan...

  17. A Web-Interface for Data Interoperability: the Spectral Library of Mt Etna Volcanic Surfaces

    Science.gov (United States)

    Colini, L.; Doumaz, F.; Spinetti, C.; Mazzarini, F.; Favalli, M.; Isola, I.; Buongiorno, M. F.; Ananasso, C.

    2014-12-01

    In the frame of the future Italian Space Agency (ASI) Space Mission PRISMA (Precursore IperSpettrale della Missione Applicativa), the Istituto Nazionale di Geofisica e Vulcanologia (INGV) coordinates the scientific project ASI-AGI (Analisi Sistemi Iperspettrali per le Applicazioni Geofisiche Integrate) aimed to study the hyperspectral volcanic applications and to identify and characterize a vicarious validation and calibration site for hyperspectral space missions. PRISMA is an Earth observation system with innovative electro-optical instrumentation which combines an hyperspectral sensor with a panchromatic medium-resolution camera. These instruments offer the scientific community and users many applications in the field of environmental monitoring, risk management, crop classification, pollution control, and Security. In this context Mt. Etna (Italy) has been choose as main site for testing the sensor capability to assess volcanic risk. The volcanic calibration and validation activities comprise the managing of a large amount of in situ hyperspectral data collected during the last 10 years. The usability and interoperability of these datasets represents a task of ASI-AGI project. For this purpose a database has been created to collect all the spectral signatures of the measured volcanic surfaces. This process has begun with the creation of the metadata structure compliant with those belonging to some standard spectral libraries such as USGS ones. Each spectral signature is described in a table containing ancillary data such as the location map of where it was collected, description of the target selected, etc. The relational database structure has been developed WOVOdat compliant. Specific tables have been formatted for each type of measurements, instruments and targets in order to query the database through a user-friendly web-interface. The interface has an upload area to populate the database and a visualization tool that allows downloading the ASCII spectral

  18. Surface Emissivity Effects on Thermodynamic Retrieval of IR Spectral Radiance

    Science.gov (United States)

    Zhou, Daniel K.; Larar, Allen M.; Smith, William L.; Liu, Xu

    2006-01-01

    The surface emissivity effect on the thermodynamic parameters (e.g., the surface skin temperature, atmospheric temperature, and moisture) retrieved from satellite infrared (IR) spectral radiance is studied. Simulation analysis demonstrates that surface emissivity plays an important role in retrieval of surface skin temperature and terrestrial boundary layer (TBL) moisture. NAST-I ultraspectral data collected during the CLAMS field campaign are used to retrieve thermodynamic properties of the atmosphere and surface. The retrievals are then validated by coincident in-situ measurements, such as sea surface temperature, radiosonde temperature and moisture profiles. Retrieved surface emissivity is also validated by that computed from the observed radiance and calculated emissions based on the retrievals of surface temperature and atmospheric profiles. In addition, retrieved surface skin temperature and emissivity are validated together by radiance comparison between the observation and retrieval-based calculation in the window region where atmospheric contribution is minimized. Both simulation and validation results have lead to the conclusion that variable surface emissivity in the inversion process is needed to obtain accurate retrievals from satellite IR spectral radiance measurements. Retrieval examples are presented to reveal that surface emissivity plays a significant role in retrieving accurate surface skin temperature and TBL thermodynamic parameters.

  19. ENSO signature in the SMOS sea surface salinity maps

    Science.gov (United States)

    Ballabrera, J.; Umbert, M.; Hoareau, N.; Turiel, A.; Font, J.

    2012-12-01

    Until recently, the role of salinity observations in the operational simulation and prediction of ENSO was neglected because of the historical lack of observations and because leading intermediate coupled models had significant predictive skill without directly accounting for salinity effects. In Ballabrera-Poy et al., (2002), the potential role of sea surface salinity (SSS) observations on the statistical predictions of ENSO was investigated. It was shown that, although SSS observations would play little role in statistical nowcasts of ENSO, they would provide a significant role in the 6-12 month predictions. The European Space Agency (ESA) Soil Moisture and Ocean Salinity (SMOS) Earth Explorer opportunity mission was launched on November 2, 2009, becoming the first satellite mission addressing the challenge of measuring SSS from space with the help of MIRAS (Microwave Imaging Radiometer with Aperture Synthesis), a novel two-dimensional interferometer operating at L-band (1.4 GHz). Although the L-band frequency is the optimal for ocean salinity measurements, the retrieval of SSS information requires special care because of the low sensitivity of the brightness temperature to SSS: from 0.2-0.8 K per salinity unit. Maps of 10-day averages of SSS in 1x1 degree boxes are distributed by the SMOS Barcelona Expert Centre on Radiometric Calibration and Ocean Salinity (SMOS-BEC, http://www.smos-bec.icm.csic.es). These maps are derived from the SMOS reprocessing campaign released to the SMOS user community in March 2011, and span the period from January 2010 through December 2011. The current accuracy of these SSS maps ranges from 0.2-0.4, depending on the ocean region being considered (Umbert et al., 2012). During the period of the reprocessing campaign, the equatorial Pacific has been in a quasi-continuous La Niña state. During the cold phases of ENSO, positive anomalies of SSS are expected with a largest anomalous values in the western warm-fresh pool. The anomalies

  20. Discrimination of zone-specific spectral signatures in normal human prostate using Raman spectroscopy.

    Science.gov (United States)

    Patel, Imran I; Martin, Francis L

    2010-12-01

    The prostate gland is the most common site of pathology in human males. Using the urethra as an anatomical reference point, it can be divided into three distinct zones known as the transition zone (TZ), peripheral zone (PZ) and central zone (CZ). The pathological conditions of benign prostatic hypertrophy and/or prostate adenocarcinoma are highly prevalent in this gland. This preliminary study set out to determine whether biochemical intra-individual differences between normal prostate zones could be identified using Raman spectroscopy with subsequent exploratory analyses. A normal (benign) prostate transverse tissue section perpendicular to the rectal surface and above the verumontanum was obtained in a paraffin-embedded block. A 10-µm-thick slice was floated onto a gold substrate, de-waxed and analysed using Raman spectroscopy (200 epithelial-cell and 140 stromal spectra/zone). Raman spectra were subsequently processed in the 1800-367 cm(-1) spectral region employing principal component analysis (PCA) to determine whether wavenumber-intensity relationships expressed as single points in hyperspace might reveal biochemical differences associated with inter-zone pathological susceptibility. Visualisation of PCA scores plots and their corresponding loadings plots highlighted 781 cm(-1) (cytosine/uracil) and 787 cm(-1) (DNA) as the key discriminating factors segregating PZ from less susceptible TZ and CZ epithelia (P prostate zones to specific pathological conditions.

  1. Enveloping Spectral Surfaces: Covariate Dependent Spectral Analysis of Categorical Time Series.

    Science.gov (United States)

    Krafty, Robert T; Xiong, Shuangyan; Stoffer, David S; Buysse, Daniel J; Hall, Martica

    2012-09-01

    Motivated by problems in Sleep Medicine and Circadian Biology, we present a method for the analysis of cross-sectional categorical time series collected from multiple subjects where the effect of static continuous-valued covariates is of interest. Toward this goal, we extend the spectral envelope methodology for the frequency domain analysis of a single categorical process to cross-sectional categorical processes that are possibly covariate dependent. The analysis introduces an enveloping spectral surface for describing the association between the frequency domain properties of qualitative time series and covariates. The resulting surface offers an intuitively interpretable measure of association between covariates and a qualitative time series by finding the maximum possible conditional power at a given frequency from scalings of the qualitative time series conditional on the covariates. The optimal scalings that maximize the power provide scientific insight by identifying the aspects of the qualitative series which have the most pronounced periodic features at a given frequency conditional on the value of the covariates. To facilitate the assessment of the dependence of the enveloping spectral surface on the covariates, we include a theory for analyzing the partial derivatives of the surface. Our approach is entirely nonparametric, and we present estimation and asymptotics in the setting of local polynomial smoothing.

  2. A Spectral Signature Shape-Based Algorithm for Landsat Image Classification

    Directory of Open Access Journals (Sweden)

    Yuanyuan Chen

    2016-08-01

    Full Text Available Land-cover datasets are crucial for earth system modeling and human-nature interaction research at local, regional and global scales. They can be obtained from remotely sensed data using image classification methods. However, in processes of image classification, spectral values have received considerable attention for most classification methods, while the spectral curve shape has seldom been used because it is difficult to be quantified. This study presents a classification method based on the observation that the spectral curve is composed of segments and certain extreme values. The presented classification method quantifies the spectral curve shape and takes full use of the spectral shape differences among land covers to classify remotely sensed images. Using this method, classification maps from TM (Thematic mapper data were obtained with an overall accuracy of 0.834 and 0.854 for two respective test areas. The approach presented in this paper, which differs from previous image classification methods that were mostly concerned with spectral “value” similarity characteristics, emphasizes the "shape" similarity characteristics of the spectral curve. Moreover, this study will be helpful for classification research on hyperspectral and multi-temporal images.

  3. Visible and near-infrared spectral signatures for adulteration assessment of extra virgin olive oil

    Science.gov (United States)

    Mignani, A. G.; Ciaccheri, L.; Ottevaere, H.; Thienpont, H.; Conte, L.; Marega, M.; Cichelli, A.; Attilio, C.; Cimato, A.

    2010-04-01

    Because of its high price, the extra virgin olive oil is frequently target for adulteration with lower quality oils. This paper presents an innovative optical technique capable of quantifying the adulteration of extra virgin olive oil caused by lowergrade olive oils. It relies on spectral fingerprinting the test liquid by means of diffuse-light absorption spectroscopy carried out by optical fiber technology in the wide 400-1700 nm spectral range. Then, a smart multivariate processing of spectroscopic data is applied for immediate prediction of adulterant concentration.

  4. Spectral Induced Polarization Signatures of Ethanol in Sand-Clay Medium

    Science.gov (United States)

    The spectral Induced Polarization (SIP) method has previously been investigated as a tool for detecting physicochemical changes occurring as result of clay-organic interactions in porous media. We performed SIP measurements with a dynamic signal analyzer (NI-4551) on laboratory ...

  5. Surface-enhanced Raman Spectral Measurements of 5-Fluorouracil in Saliva

    Directory of Open Access Journals (Sweden)

    John Murren

    2008-10-01

    Full Text Available The ability of surface-enhanced Raman spectroscopy (SERS to measure 5-fluorouracil (5-FU in saliva is presented. The approach is based on the capacity of Raman spectroscopy to provide a unique spectral signature for virtually every chemical, and the ability of SERS to provide μg/mL sensitivity. A simple sampling method, that employed 1-mm glass capillaries filled with silver-doped sol-gels, was developed to isolate 5-FU from potential interfering chemical components of saliva and simultaneously provide SERSactivity. The method involved treating a 1 mL saliva sample with 1 mL of acetic acid, drawing 10 μL of sample into a SERS-active capillary by syringe, and then measuring the SER spectrum. Quality SER spectra were obtained for samples containing as little as 2 μg of 5-FU in 1 mL saliva. The entire process, the acid pretreatment, extraction and spectral measurement, took less than 5 minutes. The SERS of 5-fluorouridine and 5-fluoro-2’-deoxyuridine, two major metabolites of 5-FU, were also measured and shown to have unique spectral peaks. These measurements suggest that disposable SERS-active capillaries could be used to measure 5-FU and metabolite concentrations in chemotherapy patient saliva, thereby providing metabolic data that would allow regulating dosage. Tentative vibrational mode assignments for 5-FU and its metabolites are also given.

  6. Insights on the Spectral Signatures of Stellar Activity and Planets from PCA

    Science.gov (United States)

    Davis, Allen B.; Cisewski, Jessi; Dumusque, Xavier; Fischer, Debra A.; Ford, Eric B.

    2017-09-01

    Photospheric velocities and stellar activity features such as spots and faculae produce measurable radial velocity signals that currently obscure the detection of sub-meter-per-second planetary signals. However, photospheric velocities are imprinted differently in a high-resolution spectrum than are Keplerian Doppler shifts. Photospheric activity produces subtle differences in the shapes of absorption lines due to differences in how temperature or pressure affects the atomic transitions. In contrast, Keplerian Doppler shifts affect every spectral line in the same way. With a high enough signal-to-noise (S/N) and resolution, statistical techniques can exploit differences in spectra to disentangle the photospheric velocities and detect lower-amplitude exoplanet signals. We use simulated disk-integrated time-series spectra and principal component analysis (PCA) to show that photospheric signals introduce spectral line variability that is distinct from that of Doppler shifts. We quantify the impact of instrumental resolution and S/N for this work.

  7. ADE Spectral Networks and Decoupling Limits of Surface Defects

    CERN Document Server

    Longhi, Pietro

    2016-01-01

    We study vacua and BPS spectra of canonical surface defects of class $\\mathcal{S}$ theories in different decoupling limits using ADE spectral networks. In some regions of the IR moduli spaces of these 2d-4d systems, the mixing between 2d and 4d BPS states is suppressed, and the spectrum of 2d-4d BPS states becomes that of a 2d $\\mathcal{N}=(2,2)$ theory. For some decoupling limits, we identify the 2d theories describing the surface defects with nonlinear sigma models and coset models that have been previously studied. We also study certain cases where the decoupling limit of a surface defect exhibits a set of vacua and a BPS spectrum that appear to be entirely new. A detailed analysis of these spectra and their wall-crossing behavior is performed.

  8. ADE spectral networks and decoupling limits of surface defects

    Science.gov (United States)

    Longhi, Pietro; Park, Chan Y.

    2017-02-01

    We study vacua and BPS spectra of canonical surface defects of class S theories in different decoupling limits using ADE spectral networks. In some regions of the IR moduli spaces of these 2d-4d systems, the mixing between 2d and 4d BPS states is suppressed, and the spectrum of 2d-4d BPS states becomes that of a 2d N = (2, 2) theory. For some decoupling limits, we identify the 2d theories describing the surface defects with nonlinear sigma models and coset models that have been previously studied. We also study certain cases where the decoupling limit of a surface defect exhibits a set of vacua and a BPS spectrum that appear to be entirely new. A detailed analysis of these spectra and their wall-crossing behavior is performed.

  9. Probing DNA-Protein Interactions on Surfaces Using Spectral Self-interference Fluorescence Microscopy

    Science.gov (United States)

    Dogan, Mehmet; Droge, Peter; Swan, Anna K.; Unlu, Selim; Goldberg, Bennett B.

    2007-03-01

    We are probing the interactions between double-stranded DNA and integration host factor (IHF) proteins [1] on surfaces using Spectral Self-interference Fluorescence Microscopy (SSFM) [2].The probing technique utilizes the spectral fringes produced by interference of direct and reflected emission from fluorescent molecules. The modified spectrum provides a unique signature of the axial position of the fluorophores. Using the SSFM technique, we probe the average location of the fluorescent markers attached to the DNA molecules to study the conformational changes in double-stranded DNA tethered to SiO2 surfaces. In the presence of IHF, a DNA bending protein, we observe reduction in the vertical position of fluorescent molecules suggesting the formation of IHF-DNA complex and IHF-induced DNA bending. We also discuss the results with different IHF strains and different binding conditions. [1] Q. Bao et. al., Gene, Vol.343 pp.99-106 (2004) [2] L.A. Moiseev et. al., Journal of Applied Physics, Vol.96, pp. 5311-5315 (2004)

  10. The influence of charge stratification on the spectral signature of partially premixed combustion in a light-duty optical engine

    KAUST Repository

    Najafabadi, M. Izadi

    2017-03-25

    The origin of light emission during low-temperature combustion in a light-duty IC engine is investigated by high-speed spectroscopy in both HCCI and PPC regimes. Chemiluminescence and thermal radiation are expected to be the dominant sources of light emission during combustion. A method has been developed to distinguish chemiluminescence from thermal radiation, and different chemiluminescing species could be identified. Different combustion modes and global equivalence ratios are analyzed in this manner. The results indicate that the spectral signature (270–540 nm range) of the combustion is highly dependent on the stratification level. A significant broadband chemiluminescence signal is detected and superimposed on all spectra. This broadband chemiluminescence signal can reach up to 100 percent of the total signal in HCCI combustion, while it drops to around 80 percent for stratified combustion (PPC). We show that this broadband signal can be used as a measure for the heat release rate. The broadband chemiluminescence did also correlate with the equivalence ratio quite well in both HCCI and PPC regimes, suggesting that the total emission in the spectral region of 330–400 nm can serve as a proxy of equivalence ratio and the rate of heat release. Regarding C2* chemiluminescence, we see two different chemical mechanisms for formation of C2* in the PPC regime: first during the early stage of combustion by the breakup of bigger molecules and the second during the late stage of combustion when soot particles are forming.

  11. The influence of charge stratification on the spectral signature of partially premixed combustion in a light-duty optical engine

    Science.gov (United States)

    Najafabadi, M. Izadi; Egelmeers, Luc; Somers, Bart; Deen, Niels; Johansson, Bengt; Dam, Nico

    2017-04-01

    The origin of light emission during low-temperature combustion in a light-duty IC engine is investigated by high-speed spectroscopy in both HCCI and PPC regimes. Chemiluminescence and thermal radiation are expected to be the dominant sources of light emission during combustion. A method has been developed to distinguish chemiluminescence from thermal radiation, and different chemiluminescing species could be identified. Different combustion modes and global equivalence ratios are analyzed in this manner. The results indicate that the spectral signature (270-540 nm range) of the combustion is highly dependent on the stratification level. A significant broadband chemiluminescence signal is detected and superimposed on all spectra. This broadband chemiluminescence signal can reach up to 100 percent of the total signal in HCCI combustion, while it drops to around 80 percent for stratified combustion (PPC). We show that this broadband signal can be used as a measure for the heat release rate. The broadband chemiluminescence did also correlate with the equivalence ratio quite well in both HCCI and PPC regimes, suggesting that the total emission in the spectral region of 330-400 nm can serve as a proxy of equivalence ratio and the rate of heat release. Regarding C2* chemiluminescence, we see two different chemical mechanisms for formation of C2* in the PPC regime: first during the early stage of combustion by the breakup of bigger molecules and the second during the late stage of combustion when soot particles are forming.

  12. Quantitative characterization of surface topography using spectral analysis

    Science.gov (United States)

    Jacobs, Tevis D. B.; Junge, Till; Pastewka, Lars

    2017-03-01

    Roughness determines many functional properties of surfaces, such as adhesion, friction, and (thermal and electrical) contact conductance. Recent analytical models and simulations enable quantitative prediction of these properties from knowledge of the power spectral density (PSD) of the surface topography. The utility of the PSD is that it contains statistical information that is unbiased by the particular scan size and pixel resolution chosen by the researcher. In this article, we first review the mathematical definition of the PSD, including the one- and two-dimensional cases, and common variations of each. We then discuss strategies for reconstructing an accurate PSD of a surface using topography measurements at different size scales. Finally, we discuss detecting and mitigating artifacts at the smallest scales, and computing upper/lower bounds on functional properties obtained from models. We accompany our discussion with virtual measurements on computer-generated surfaces. This discussion summarizes how to analyze topography measurements to reconstruct a reliable PSD. Analytical models demonstrate the potential for tuning functional properties by rationally tailoring surface topography—however, this potential can only be achieved through the accurate, quantitative reconstruction of the PSDs of real-world surfaces.

  13. Asteroid surface archaeology: Identification of eroded impact structures by spectral properties on (4) Vesta

    Science.gov (United States)

    Hoffmann, M.; Nathues, A.; Schäfer, M.; Schmedemann, N.; Vincent, J.; Russell, C.

    2014-07-01

    Introduction: Vesta's surface material is characterized as a deep regolith [1,2], mobilized by countless impacts. The almost catastrophic impact near Vesta's south pole, which has created the Rheasilvia basin, and the partly overlapping older impact of similar size, Veneneia, have not only reshaped the areas of their interior (roughly 50 % of the Vesta surface), but also emplaced each time a huge ejecta blanket of similar size, thus covering the whole remaining surface. In this context, pristine and even younger morphologic features have been erased. However, the spectral signatures of the early differentiation and alteration products by impacts have partially remained in situ. While near the north pole several large old eroded impact features are visible, the equatorial zone close to the basin rims seems to be void of those. Since it is unlikely, that this zone has been entirely avoided by large projectiles, in this area the results of such impacts may have left morphologically not detectable remnants: Individual distribution of particle sizes and altered photometric properties, excavated layers, shock metamorphism, melt generation inside particles and on macroscopic scales, and emplacement of exogenous projectile material. An analysis by color ratio images and spatial profiles of diagnostic spectral parameters reveals such features. Results: Based on local spectroscopic evidence we have detected eroded impact features of three categories: 1) Small craters with diameters of a few kilometers, 2) Large craters or, if even larger, incipient impact basins, 3) Sub-global ejecta blankets. The eastern part of Feralia Planitia, diameter 140 km, has little evidence of a round outline in the shape model, but it features spectral gradients towards its center. A feature of similar size, centered north of Lucaria Tholus becomes only visible by a similar spectra gradient and a circular outline in specific spectral ratio mosaics. These features seem to be related to the

  14. UV spectral filtering by surface structured multilayer mirrors.

    Science.gov (United States)

    Huang, Qiushi; Paardekooper, Daniel Mathijs; Zoethout, Erwin; Medvedev, V V; van de Kruijs, Robbert; Bosgra, Jeroen; Louis, Eric; Bijkerk, Fred

    2014-03-01

    A surface structured extreme ultraviolet multilayer mirror was developed showing full band suppression of UV (λ=100-400  nm) and simultaneously a high reflectance of EUV light (λ=13.5  nm). The surface structure consists of Si pyramids, which are substantially transparent for EUV but reflective for UV light. The reflected UV is filtered out by blazed diffraction, interference, and absorption. A first demonstration pyramid structure was fabricated on a multilayer by using a straightforward deposition technique. It shows an average suppression of 14 times over the whole UV range and an EUV reflectance of 56.2% at 13.5 nm. This robust scheme can be used as a spectral purity solution for all XUV sources that emit longer wavelength radiation as well.

  15. Surface Signatures of an Underground Explosion as Captured by Photogrammetry

    Science.gov (United States)

    Schultz-Fellenz, E. S.; Sussman, A. J.; Swanson, E.; Coppersmith, R.; Cooley, J.; Rougier, E.; Larmat, C. S.; Norskog, K.

    2016-12-01

    This study employed high-resolution photogrammetric modeling to quantify cm-scale surface topographic changes resulting from a 5000kg underground chemical explosion. The test occurred in April 2016 at a depth of 76m within a quartz monzonite intrusion in southern Nevada. The field area was a 210m x 150m polygon broadly centered on the explosion's emplacement hole. A grid of ground control points (GCPs) installed in the field area established control within the collection boundaries and ensured high-resolution digital model parameterization. Using RTK GPS techniques, GCP targets were surveyed in the days before and then again immediately after the underground explosion. A quadcopter UAS with a 12MP camera payload captured overlapping imagery at two flight altitudes (10m and 30m AGL) along automated flight courses for consistency and repeatability. The overlapping imagery was used to generate two digital elevation models, pre-shot and post-shot, for each of the flight altitudes. Spatial analyses of the DEMs and orthoimagery show uplift on the order of 1 to 18cm in the immediate area near ground zero. Other features such as alluvial fracturing appear in the photogrammetric and topographic datasets. Portions of the nearby granite outcrop experienced rock fall and rock rotation. The study detected erosional and depositional features on the test bed and adjacent to it. In addition to vertical change, pre-shot and post-shot surveys of the GCPs suggest evidence for lateral motion on the test bed surface, with movement away from surface ground zero on the order of 1 to 3cm. Results demonstrate that UAS photogrammetry method provides an efficient, high-fidelity, non-invasive method to quantify surface deformation. The photogrammetry data allow quantification of permanent surface deformation and of the spatial extent of damage. These constraints are necessary to develop hydrodynamic and seismic models of explosions that can be verified against recorded seismic data.

  16. Radiative Signatures of Reconnection in X-ray Binary Spectral States

    Science.gov (United States)

    Uzdensky, Dmitri

    Accreting black holes (BHs) in Galactic X-ray Binary (XRB) systems represent some of the main targets of space-based high-energy observatories such as NASA s RXTE, Chandra, and NuSTAR, as well as the international observatories XMM Newton, INTEGRAL, Suzaku (Astro-E), and Astro-H. The overall radiative energy output (mostly X-rays) is ultimately powered by the conversion of the gravitational potential energy of the matter falling onto a black hole and forming an accretion disk or a hot accretion flow around it. Observationally, these systems are found to cycle between a few discrete spectral states, characterized by different overall X-ray power and spectral hardness: (1) the bright thermal high-soft state, dominated by a soft (1 keV) thermal component attributed to a thin dense accretion disk with a relatively weak corona producing a power-law tail emission to at least 1 MeV; (2) the low-hard state, showing no signs of a thin accretion disk and dominated by a single hard (with index ~ -1.7) power law truncating at about 100 keV; and (3) the bright Steep Power Law state with both a standard thin disk and a powerful coronal power-law (with index about -2.5) emission extending to at least 1 MeV. Explaining the key features of these nonthermal spectra, i.e., their power law indices and high-energy cutoffs, is one of the outstanding problems in high-energy astrophysics. The hard (10keV 1MeV) X-ray emission in these states is believed to be produced by inverse-Compton scattering in relativistically-hot gas, presumably heated by magnetic reconnection processes, and forming either an accretion disk corona or the hot accretion flow itself. Since the radiative cooling time of the energetic electrons in the intense radiation fields found in these systems is very short, the observed non-thermal hard X-ray spectra should directly reflect the instantaneous energy spectra of the electrons accelerated in reconnection events. Recent advances in kinetic simulations of reconnection

  17. Detection of illicit drugs with the technique of spectral fluorescence signatures (SFS)

    Science.gov (United States)

    Poryvkina, Larisa; Babichenko, Sergey

    2010-10-01

    The SFS technology has already proved its analytical capabilities in a variety of industrial and environmental tasks. Recently it has been introduced for forensic applications. The key features of the SFS method - measuring a 3-dimensional spectrum of fluorescence of the sample (intensity versus excitation and emission wavelengths) with following recognition of specific spectral patterns of SFS responsible for individual drugs - provide an effective tool for the analysis of untreated seized samples, without any separation of the substance of interest from its mixture with accompanying cutting agents and diluents as a preparatory step. In such approach the chemical analysis of the sample is substituted by the analysis of SFS matrix visualized as an optical image. The SFS technology of drug detection is realized by NarTest® NTX2000 analyzer, compact device intended to measure suspicious samples in liquid, solid and powder forms. It simplifies the detection process due to fully automated procedures of SFS measuring and integrated expert system for recognition of spectral patterns. Presently the expert system of NTX2000 is able to detect marijuana, cocaine, heroin, MDMA, amphetamine and methamphetamine with the detection limit down to 5% of the drug concentration in various mixtures. The numerous tests with street samples confirmed that the use of SFS method provides reliable results with high sensitivity and selectivity for identification of drugs of abuse. More than 3000 street samples of the aforesaid drugs were analyzed with NTX2000 during validation process, and the correspondence of SFS results and conclusions of standard forensic analyses with GC/MS techniques was in 99.4% cases.

  18. Effect of a cracked surface of porous silicon on the behaviour of the acoustic signature

    Directory of Open Access Journals (Sweden)

    Bouhedja Samia

    2014-06-01

    Full Text Available We study in this work the effect of a crack, located on the porous silicon, Psi, surface on the propagation of Rayleigh waves. We simulate and analyse the acoustic signature V(z according porosity at 142 MHz, to study the microstructure of PSi around the crack.

  19. Aqueous Cation-Amide Binding: Free Energies and IR Spectral Signatures by Ab Initio Molecular Dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Pluharova, Eva; Baer, Marcel D.; Mundy, Christopher J.; Schmidt, Burkhard; Jungwirth, Pavel

    2014-07-03

    Understanding specific ion effects on proteins remains a considerable challenge. N-methylacetamide serves as a useful proxy for the protein backbone that can be well characterized both experimentally and theoretically. The spectroscopic signatures in the amide I band reflecting the strength of the interaction of alkali cations and alkali earth dications with the carbonyl group remain difficult to assign and controversial to interpret. Herein, we directly compute the IR shifts corresponding to the binding of either sodium or calcium to aqueous N-methylacetamide using ab initio molecular dynamics simulations. We show that the two cations interact with aqueous N-methylacetamide with different affinities and in different geometries. Since sodium exhibits a weak interaction with the carbonyl group, the resulting amide I band is similar to an unperturbed carbonyl group undergoing aqueous solvation. In contrast, the stronger calcium binding results in a clear IR shift with respect to N-methylacetamide in pure water. Support from the Czech Ministry of Education (grant LH12001) is gratefully acknowledged. EP thanks the International Max-Planck Research School for support and the Alternative Sponsored Fellowship program at Pacific Northwest National Laboratory (PNNL). PJ acknowledges the Praemium Academie award from the Academy of Sciences. Calculations of the free energy profiles were made possible through generous allocation of computer time from the North-German Supercomputing Alliance (HLRN). Calculations of vibrational spectra were performed in part using the computational resources in the National Energy Research Supercomputing Center (NERSC) at Lawrence Berkeley National Laboratory. This work was supported by National Science Foundation grant CHE-0431312. CJM is supported by the U.S. Department of Energy`s (DOE) Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences. PNNL is operated for the Department of Energy by Battelle. MDB is

  20. A holistic view of unstable dark matter. Spectral and anisotropy signatures in astrophysical backgrounds

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Le

    2010-11-15

    The nature of dark matter is one of the key outstanding problems in both particle and astrophysics. If dark matter decays or annihilates into electrons and positrons, it can affect diffuse radiation backgrounds observed in astrophysics. In this thesis, we propose a new, more general analysis of constraints on dark matter models. For any decaying dark matter model, constraints on mass and lifetime can be obtained by folding the specific dark matter decay spectrum with a response function. We derive these response functions from full-sky radio surveys and Fermi-LAT gamma-ray observations as well as from the local positron fluxes measured by the PAMELA satellite experiment and apply them to place constraints on some specific dark matter decay models. We also discuss the influence of astrophysical uncertainties on the response function, such as the uncertainties from propagation models and from the spatial distribution of the dark matter. Moreover, an anisotropy analysis of full-sky emission gamma-ray and radio maps is performed to identify possible signatures of annihilating dark matter. We calculate angular power spectra of the cosmological background of synchrotron emission from dark matter annihilations into electron positron pairs. We compare the power spectra with the anisotropy of astrophysical and cosmological radio backgrounds, from normal galaxies, radio-galaxies, galaxy cluster accretion shocks, the cosmic microwave background and Galactic foregrounds. In addition, we develop a numerical tool to compute gamma-ray emission from such electrons and positrons diffusing in the smooth host halo and in substructure halos with masses down to 10{sup -6}M{sub s}un. We show that, unlike the total gamma-ray angular power spectrum observed by Fermi-LAT, the angular power spectrum from the inverse Compton scattering is exponentially suppressed below an angular scale determined by the diffusion length of electrons and positrons. (orig.)

  1. The 1600 Å Emission Bump in Protoplanetary Disks: A Spectral Signature of H2O Dissociation

    Science.gov (United States)

    France, Kevin; Roueff, Evelyne; Abgrall, Hervé

    2017-08-01

    The FUV continuum spectrum of many accreting pre-main sequence stars, Classical T Tauri Stars (CTTSs), does not continue smoothly from the well-studied Balmer continuum emission in the NUV, suggesting that additional processes contribute to the short-wavelength emission in these objects. The most notable spectral feature in the FUV continuum of some CTTSs is a broad emission approximately centered at 1600 Å, which has been referred to as the “1600 Å Bump.” The origin of this feature remains unclear. In an effort to better understand the molecular properties of planet-forming disks and the UV spectral properties of accreting protostars, we have assembled archival FUV spectra of 37 disk-hosting systems observed by the Hubble Space Telescope-Cosmic Origins Spectrograph. Clear 1600 Å Bump emission is observed above the smooth, underlying 1100-1800 Å continuum spectrum in 19/37 Classical T Tauri disks in the HST-COS sample, with the detection rate in transition disks (8/8) being much higher than that in primordial or non-transition sources (11/29). We describe a spectral deconvolution analysis to separate the Bump (spanning 1490-1690 Å) from the underlying FUV continuum, finding an average Bump luminosity L(Bump) ≈ 7 × 1029 erg s-1. Parameterizing the Bump with a combination of Gaussian and polynomial components, we find that the 1600 Å Bump is characterized by a peak wavelength λ o = 1598.6 ± 3.3 Å, with FWHM = 35.8 ± 19.1 Å. Contrary to previous studies, we find that this feature is inconsistent with models of H2 excited by electron -impact. We show that this Bump makes up between 5%-50% of the total FUV continuum emission in the 1490-1690 Å band and emits roughly 10%-80% of the total fluorescent H2 luminosity for stars with well-defined Bump features. Energetically, this suggests that the carrier of the 1600 Å Bump emission is powered by Lyα photons. We argue that the most likely mechanism is Lyα-driven dissociation of H2O in the inner disk, r

  2. Sleep respiratory disturbances and arousals at moderate altitude have overlapping electroencephalogram spectral signatures.

    Science.gov (United States)

    Stadelmann, Katrin; Latshang, Tsogyal D; Tarokh, Leila; Lo Cascio, Christian M; Tesler, Noemi; Stoewhas, Anne-Christin; Kohler, Malcolm; Bloch, Konrad E; Huber, Reto; Achermann, Peter

    2014-08-01

    An ascent to altitude has been shown to result in more central apneas and a shift towards lighter sleep in healthy individuals. This study employs spectral analysis to investigate the impact of respiratory disturbances (central/obstructive apnea and hypopnea or periodic breathing) at moderate altitude on the sleep electroencephalogram (EEG) and to compare EEG changes resulting from respiratory disturbances and arousals. Data were collected from 51 healthy male subjects who spent 1 night at moderate altitude (2590 m). Power density spectra of Stage 2 sleep were calculated in a subset (20) of these participants with sufficient artefact-free data for (a) epochs with respiratory events without an accompanying arousal, (b) epochs containing an arousal and (c) epochs of undisturbed Stage 2 sleep containing neither arousal nor respiratory events. Both arousals and respiratory disturbances resulted in reduced power in the delta, theta and spindle frequency range and increased beta power compared to undisturbed sleep. The similarity of the EEG changes resulting from altitude-induced respiratory disturbances and arousals indicates that central apneas are associated with micro-arousals, not apparent by visual inspection of the EEG. Our findings may have implications for sleep in patients and mountain tourists with central apneas and suggest that respiratory disturbances not accompanied by an arousal may, none the less, impact sleep quality and impair recuperative processes associated with sleep more than previously believed.

  3. Supernova Legacy Survey: Using Spectral Signatures To Improve Type Ia Supernovae As Distance Indicators

    CERN Document Server

    Walker, E S; Sullivan, M; Howell, D A; Astier, P; Balland, C; Basa, S; Bronder, T J; Carlberg, R; Conley, A; Fouchez, D; Guy, J; Hardin, D; Pain, R; Perrett, K; Pritchet, C; Regnault, N; Rich, J; Aldering, G; Fakhouri, H K; Kronborg, T; Palanque-Delabrouille, N; Perlmutter, S; Ruhlmann-Kleider, V; Zhang, T

    2010-01-01

    GMOS optical long-slit spectroscopy at the Gemini-North telescope was used to classify targets from the Supernova Legacy Survey (SNLS) from July 2005 and May 2006 - May 2008. During this time, 95 objects were observed. Where possible the objects' redshifts (z) were measured from narrow emission or absorption features in the host galaxy spectrum, otherwise they were measured from the broader supernova features. We present spectra of 68 confirmed or probable SNe Ia from SNLS with redshifts in the range 0.17 \\leq z \\leq 1.02. In combination with earlier SNLS Gemini and VLT spectra, we used these new observations to measure pseudo-equivalent widths (EWs) of three spectral features - CaII H&K, SiII and MgII - in 144 objects and compared them to the EWs of low-redshift SNe Ia from a sample drawn from the literature. No signs of changes with z are seen for the CaII H&K and MgII features. Systematically lower EW SiII is seen at high redshift, but this can be explained by a change in demographics of the SNe Ia...

  4. The Sternheimer-GW method and the spectral signatures of plasmonic polarons

    Science.gov (United States)

    Giustino, Feliciano

    During the past three decades the GW method has emerged among the most promising electronic structure techniques for predictive calculations of quasiparticle band structures. In order to simplify the GW work-flow while at the same time improving the calculation accuracy, we developed the Sternheimer-GW method. In Sternheimer-GW both the screened Coulomb interaction and the electron Green's function are evaluated by using exclusively occupied Kohn-Sham states, as in density-functional perturbation theory. In this talk I will review the basics of Sternheimer-GW, and I will discuss two recent applications to semiconductors and superconductors. In the case of semiconductors we calculated complete energy- and momentum-resolved spectral functions by combining Sternheimer-GW with the cumulant expansion approach. This study revealed the existence of band structure replicas which arise from electron-plasmon interactions. In the case of superconductors we calculated the Coulomb pseudo-potential from first principles, and combined this approach with the Eliashberg theory of the superconducting critical temperature. This work was supported by the Leverhulme Trust (RL-2012-001), the European Research Council (EU FP7/ERC 239578), the UK Engineering and Physical Sciences Research Council (EP/J009857/1), and the Graphene Flagship (EU FP7/604391).

  5. Investigation of land-use spectral signatures. Ph.D. Thesis. Final Report

    Science.gov (United States)

    Hagewood, J. F.

    1975-01-01

    A technique was developed to obtain bidirectional reflectance data from natural surfaces by using a folding mirror to transfer the reflected energy from the test surface to a spectroradiometer. The folding mirror was a first surface reflector made by stretching Mylar vacuum coated with aluminum over a light weight frame. The optically folding mirror was positioned over the test surfaces with a moveable platform for both laboratory and field tests. Field tests were conducted using a tethered balloon system to position the folding mirror. A spectroradiometer was designed and built specifically for this investigation. The spectroradiometer had an angular field of view of twenty-four minutes in one axis and ten minutes in the other axis. The radiometer was capable of detecting energies in small bandwidths throughout the electromagnetic spectrum from 0.3 microns to 3.0 microns. Bidirectional reflectance data and variations in the data with source angles were obtained for Saint Augustine grass, Bermuda grass, and a black alluvium soil from the Mississippi River delta.

  6. The Infrared Spectral Signature of Water Ice in the Vacuum Cryogenic AI&T Environment

    Science.gov (United States)

    2005-12-31

    15 8. Surface R efl ections...equivalently n = (1/’/2) [(6’ 2 + F,Ŗ)1/2 + s’]" 2 & k = (11V2) [(F,2 + E,,2)1/2 - T,]1/2 (6) Broadly speaking , n controls reflection, refraction, and

  7. Surface signature of Mediterranean water eddies in the Northeastern Atlantic: effect of the upper ocean stratification

    Directory of Open Access Journals (Sweden)

    I. Bashmachnikov

    2012-11-01

    Full Text Available Meddies, intra-thermocline eddies of Mediterranean water, can often be detected at the sea surface as positive sea-level anomalies. Here we study the surface signature of several meddies tracked with RAFOS floats and AVISO altimetry.

    While pushing its way through the water column, a meddy raises isopycnals above. As a consequence of potential vorticity conservation, negative relative vorticity is generated in the upper layer. During the initial period of meddy acceleration after meddy formation or after a stagnation stage, a cyclonic signal is also generated at the sea-surface, but mostly the anticyclonic surface signal follows the meddy.

    Based on geostrophy and potential vorticity balance, we present theoretical estimates of the intensity of the surface signature. It appears to be proportional to the meddy core radius and to the Coriolis parameter, and inversely proportional to the core depth and buoyancy frequency. This indicates that surface signature of a meddy may be strongly reduced by the upper ocean stratification. Using climatic distribution of the stratification intensity, we claim that the southernmost limit for detection in altimetry of small meddies (with radii on the order of 10–15 km should lie in the subtropics (35–45° N, while large meddies (with radii of 25–30 km could be detected as far south as the northern tropics (25–35° N. Those results agree with observations.

  8. Mapping aboveground forest biomass combining dendrometric data and spectral signature of forest species

    Science.gov (United States)

    Avocat, H.; Tourneux, F.

    2013-12-01

    Accurate measures and explicit spatial representations of forest biomass compose an important aspect to model the forest productivity and crops, and to implement sustainable forest management. Several methods have been developed to estimate and to map forest biomass, combining point-sources measurements of biophysical variables such as diameter-at-breast height (DBH), tree height, crown size, crown length, crown volume and remote sensing data (spectral vegetation index values). In this study, we propose a new method for aboveground biomass (AGB) mapping of forests and isolated trees. This method is tested on a 1100 km2 area located in the eastern France. In contrast to most of studies, our model is not calibrated using field plot measurements or point-source inventory data. The primary goal of this model is to propose an accessible and reproducible method for AGB mapping of temperate forests, by combining standard biomass values coming from bibliography and remotely sensed data. This method relies on three steps. (1) The first step consists of produce a map of wooded areas including small woods and isolated trees, and to identify the major forest stands. To do this, we use an unsupervised classification of a Landsat 7 ETM+ image. Results are compared and improved with various land cover data. (2) The second step consists of extract the normalized difference vegetation index (NDVI) values of main forest stands. (3) Finally, these values are combined with standard AGB values provided by bibliography, to calibrate four AGB estimation models of different forest types (broadleaves, coniferous, coppices, and mixed stands). This method provides a map of aboveground biomass for forests and isolated trees with a 30 meters spatial resolution. Results demonstrate that 71 % of AGB values for hardwoods vary between 143 and 363 t.ha-1, i.e. × 1 standard deviation around the average. For coniferous stands, most of values of AGB range from 167 to 256 t.ha-1.

  9. Spectral induced polarization signatures from a crude-oil contaminated site undergoing biodegradation, Bemidji, MN

    Science.gov (United States)

    Mewafy, F.; Atekwana, E. A.; Ntarlagiannis, D.; Slater, L. D.; Revil, A.; Skold, M.; Gorby, Y.; Werkema, D.

    2010-12-01

    The spectral induced polarization (SIP) technique is a promising biogeophysical technique for sensing microbially-induced changes in the petrophysical properties of porous media. Recent studies by Schmutz et al. for samples freshly contaminated with oil show a well defined relaxation peak in the 0.001-0.1 Hz frequency rangewith the magnitude of the phase and resistivity increasing with increase in the relative saturation of the oil. In this study, we extend work of Abdel Aal et al. by acquiring SIP measurements in the frequency range between 0.001 and 1000 Hz on sediment cores retrieved from a hydrocarbon contaminated site where intrinsic bioremediation is occurring. Our results show the following: (1) in general for both the saturated and unsaturated zone samples, the real and imaginary conductivity for samples from within the plume are higher than those for background samples; (2) the imaginary conductivity results show a well defined peak in the frequency range between 0.001 - 0.01 Hz for contaminated samples with the magnitude higher for samples from the smear zone (contaminated with residual-phase hydrocarbon), exceeding values obtained for samples contaminated with dissolved-phase hydrocarbons; (3) a secondary peak not observed in uncontaminated samples is also observed around 100 Hz for the contaminated samples. Our results are consistent with the Abel Aal et al. study suggesting that biodegradation increases the magnitude of the imaginary conductivity response. The peak at the lower frequency may be due to the polarization of the Stern layer as suggested by Schmutz et al. Our laboratory SIP measurements from core samples are consistent with downhole time domain induced polarization measurements that also how that the contaminated borehole is more chargeable than the background borehole.

  10. Europa: Characterization and interpretation of global spectral surface units

    Science.gov (United States)

    Nelson, M.L.; McCord, T.B.; Clark, R.N.; Johnson, T.V.; Matson, D.L.; Mosher, J.A.; Soderblom, L.A.

    1986-01-01

    The Voyager global multispectral mosaic of the Galilean satellite Europa (T. V. Johnson, L. A. Soderblom, J. A. Mosher, G. E. Danielson, A. F. Cook, and P. Kupferman, 1983, J. Geophys. Res. 88, 5789-5805) was analyzed to map surface units with similar optical properties (T. B. McCord, M. L. Nelson, R. N. Clark, A. Meloy, W. Harrison, T. V. Johnson, D. L. Matson, J. A. Mosher, and L. Soderblom, 1982, Bull Amer. Astron. Soc. 14, 737). Color assignments in the unit map are indicative of the spectral nature of the unit. The unit maps make it possible to infer extensions of the geologic units mapped by B. K. Lucchitta and L. A. Soderblom (1982, in Satellites of Jupiter, pp. 521-555, Univ. of Arizona Press, Tucson) beyond the region covered in the high-resolution imagery. The most striking feature in the unit maps is a strong hemispheric asymmetry. It is seen most clearly in the ultraviolet/violet albedo ratio image, because the asymmetry becomes more intense as the wavelength decreases. It appears as if the surface has been darkened, most intensely in the center of the trailing hemisphere and decreasing gradually, essentially as the cosine of the angle from the antapex of motion, to a minimum in the center of the leading hemisphere. The cosine pattern suggests that the darkening is exogenic in origin and is interpreted as evidence of alteration of the surface by ion bombardment from the Jovian magnetosphere. ?? 1986.

  11. Polarized spectral combs probe optical fiber surface plasmons.

    Science.gov (United States)

    Caucheteur, Christophe; Voisin, Valérie; Albert, Jacques

    2013-02-11

    The high-order cladding modes of conventional single mode fiber come in semi-degenerate pairs corresponding to mostly radially or mostly azimuthally polarized light. Using tilted fiber Bragg gratings to excite these mode families separately, we show how plasmonic coupling to a thin gold coating on the surface of the fiber modifies the effective indices of the modes differently according to polarization and to mode order. In particular, we show the existence of a single "apolarized" grating resonance, with equal effective index for all input polarization states. This special resonance provides direct evidence of the excitation of a surface plasmon on the metal surface but also an absolute wavelength reference that allows for the precise localization of the most sensitive resonances in refractometric and biochemical sensing applications. Two plasmon interrogation methods are proposed, based on wavelength and amplitude measurements. Finally, we use a biotin-streptavidin biomolecular recognition experiment to demonstrate that differential spectral transmission measurements of a fine comb of cladding mode resonances in the vicinity of the apolarized resonance provide the most accurate method to extract information from plasmon-assisted Tilted fiber Bragg gratings, down to pM concentrations and at least 10(-5) refractive index changes.

  12. Areal-Averaged Spectral Surface Albedo in an Atlantic Coastal Area: Estimation from Ground-Based Transmission

    Directory of Open Access Journals (Sweden)

    Evgueni Kassianov

    2017-07-01

    Full Text Available Tower-based data combined with high-resolution satellite products have been used to produce surface albedo at various spatial scales over land. Because tower-based albedo data are available at only a few sites, surface albedos using these combined data are spatially limited. Moreover, tower-based albedo data are not representative of highly heterogeneous regions. To produce areal-averaged and spectrally-resolved surface albedo for regions with various degrees of surface heterogeneity, we have developed a transmission-based retrieval and demonstrated its feasibility for relatively homogeneous land surfaces. Here, we demonstrate its feasibility for a highly heterogeneous coastal region. We use the atmospheric transmission measured during a 19-month period (June 2009–December 2010 by a ground-based Multi-Filter Rotating Shadowband Radiometer (MFRSR at five wavelengths (0.415, 0.5, 0.615, 0.673 and 0.87 µm at the Department of Energy’s Atmospheric Radiation Measurement (ARM Mobile Facility (AMF site located on Graciosa Island. We compare the MFRSR-retrieved areal-averaged surface albedo with albedo derived from Moderate Resolution Imaging Spectroradiometer (MODIS observations, and also a composite-based albedo. We demonstrate that these three methods produce similar spectral signatures of surface albedo; however, the MFRSR-retrieved albedo, is higher on average (≤0.04 than the MODIS-based areal-averaged surface albedo and the largest difference occurs in winter.

  13. Segmenting and extracting terrain surface signatures from fully polarimetric multilook SIR-C data

    Science.gov (United States)

    Geaga, Jorge V.

    2016-05-01

    We report results from the segmenting and study of terrain surface signatures of fully polarimetric multilook L-band and C-band SIR-C data. Entropy/alpha/anisotropy decomposition features are available from single multilook pixel data. This eliminates the need to average data from several pixels. Entropy and alpha are utilized in the segmentation along with features we have developed primarily from the eigenanalysis of the Kennaugh matrices of multilook data. We have previously reported on our algorithm for segmenting fully polarimetric single look TerraSAR-X, multilook SIR-C and 7 band Landsat 5 data featuring the iterative application of a feedforward neural network with one hidden layer. A comparison of signatures from simultaneously recorded data at L and C bands is presented. The terrain surfaces surveyed include the ocean, lakes, lake ice, bare ground, desert salt flats, lava beds, vegetation, sand dunes, rough desert surfaces, agricultural and urban areas.

  14. Advanced discriminating criteria for natural organic substances of cultural heritage interest: spectral decomposition and multivariate analyses of FT-Raman and FT-IR signatures.

    Science.gov (United States)

    Daher, Céline; Bellot-Gurlet, Ludovic; Le Hô, Anne-Solenn; Paris, Céline; Regert, Martine

    2013-10-15

    Natural organic substances are involved in many aspects of the cultural heritage field. Their presence in different forms (raw, heated, mixed), with various conservation states, constitutes a real challenge regarding their recognition and discrimination. Their characterization usually involves the use of separative techniques which imply destructive sampling and specific analytical preparations. Here we propose a non destructive approach using FT-Raman and infrared spectroscopies for the identification and differentiation of natural organic substances. Because of their related functional groups, they usually present similar vibrational signatures. Nevertheless the use of appropriate signal treatment and statistical analysis was successfully carried out to overcome this limitation, then proposing new objective discriminating methodology to identify these substances. Spectral decomposition calculations were performed on the CH stretching region of a large set of reference materials such as resins, oils, animal glues, and gums. Multivariate analyses (Principal Component Analyses) were then performed on the fitting parameters, and new discriminating criteria were established. A set of previously characterized archeological resins, with different surface aspects or alteration states, was analyzed using the same methodology. These testing samples validate the efficiency of our discriminating criteria established on the reference corpus. Moreover, we proved that some alteration or ageing of organic materials is not an issue to their recognition.

  15. Structural Signatures of Enzyme Binding Pockets from Order-Independent Surface Alignment: A Study of Metalloendopeptidase and NAD Binding Proteins

    Science.gov (United States)

    Dundas, Joe; Adamian, Larisa; Liang, Jie

    2011-01-01

    Detecting similarities between local binding surfaces can facilitate identification of enzyme binding sites, prediction of enzyme functions, as well as aid in our understanding of enzyme mechanisms. A challenging task is to construct a template of local surface characteristics for a specific enzyme function or binding activity, as the size and shape of binding surfaces of a biochemical function often varies. Here we introduce the concept of signature binding pockets, which captures information about preserved and varied atomic positions at multi-resolution levels. For proteins with complex enzyme binding and activity, multiple signatures arise naturally in our model, which form a signature basis set that characterize this class of proteins. Both signatures and signature basis set can be automatically constructed by a method called Solar (Signature Of Local Active Regions). This method is based on a sequence order independent alignment of computed binding surface pockets. Solar also provides a structure based multiple sequence fragment alignment (MSFA) to facilitate interpretation of computed signatures. For studying a family of evolutionary related proteins, we show that for metzincin metalloendopeptidase, which has a broad spectrum of substrate binding, signature and basis set pockets can be used to discriminate metzincins from other enzymes, to predict the subclass of enzyme functions, and to identify the specific binding surfaces. For studying unrelated proteins which have evolved to bind to the same NAD co-factor, signatures of NAD binding pockets can be constructed and can be used to predict NAD binding proteins and to locate NAD binding pockets. By measuring preservation ratio and location variation, our method can identify residues and atoms important for binding affinity and specificity. In both cases, we show that signatures and signature basis set reveal significant biological insight. PMID:21145898

  16. Magnetic Signatures and Curie Surface Trend Across an Arc-Continent Collision Zone: An Example from Central Philippines

    Science.gov (United States)

    Manalo, Pearlyn C.; Dimalanta, Carla B.; Ramos, Noelynna T.; Faustino-Eslava, Decibel V.; Queaño, Karlo L.; Yumul, Graciano P.

    2016-05-01

    Ground and aeromagnetic data are combined to characterize the onshore and offshore magnetic properties of the central Philippines, whose tectonic setting is complicated by opposing subduction zones, large-scale strike-slip faulting and arc-continent collision. The striking difference between the magnetic signatures of the islands with established continental affinity and those of the islands belonging to the island arc terrane is observed. Negative magnetic anomalies are registered over the continental terrane, while positive magnetic anomalies are observed over the Philippine Mobile Belt. Several linear features in the magnetic anomaly map coincide with the trace of the Philippine Fault and its splays. Power spectral analysis of the magnetic data reveals that the Curie depth across the central Philippines varies. The deepest point of the magnetic crust is beneath Mindoro Island at 32 km. The Curie surface shallows toward the east: the Curie surface is 21 km deep between the islands of Sibuyan and Masbate, and 18 km deep at the junction of Buruanga Peninsula and Panay Island. The shallowest Curie surface (18 km) coincides with the boundary of the arc-continent collision, signifying the obduction of mantle rocks over the continental basement. Comparison of the calculated Curie depth with recent crustal thickness models reveals the same eastwards thinning trend and range of depths. The coincidence of the magnetic boundary and the density boundary may support the existence of a compositional boundary that reflects the crust-mantle interface.

  17. Albedos and spectral signatures determination and it connection to geological processes: Simile between Earth and other solar system bodies

    Science.gov (United States)

    Suarez, J.; Ochoa, L.; Saavedra, F.

    2017-07-01

    Remote sensing has always been the best investigation tool for planetary sciences. In this research have been used data of Surface albedo, electromagnetic spectra and satelital imagery in search of understanding glacier dynamics in some bodies of the solar system, and how it's related to their compositions and associated geological processes, this methodology is very common in icy moons studies. Through analytic software's some albedos map's and geomorphological analysis were made that allow interpretation of different types of ice in the glacier's and it's interaction with other materials, almost all the images were worked in the visible and infrared ranges of the spectrum; spectral data were later used to connect the reflectance whit chemical and reologic properties of the compounds studied. It have been concluded that the albedo analysis is an effective tool to differentiate materials in the bodies surfaces, but the application of spectral data is necessary to know the exact compounds of the glaciers and to have a better understanding of the icy bodies.

  18. Comprehensive Assignment of Mass Spectral Signatures from Individual Bacillus atrophaeus Spores in Matrix-Free Bioaerosol Mass Spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Srivastava, A; Pitesky, M; Steele, P; Tobias, H; Fergenson, D P; Horn, J; Russell, S C; Czerwieniec, G; Lebrilla, C; Gard, E E; Frank, M

    2004-10-22

    We have conducted studies to fully characterize the mass spectral signature of individual Bacillus atrophaeus, previously known as Bacillus subtilis var niger or Bacillus globigii, spores obtained in matrix-free bioaerosol mass spectrometry (BAMS). Mass spectra of spores grown in unlabeled, {sup 13}C-labeled and {sup 15}N-labeled growth media are used to determine the number of carbon and nitrogen atoms associated with each mass peak. To determine the parent ion structure associated with fragment ions present in the spore spectra, the mass-to-charge (m/z) fragmentation pattern of several chemical standards was obtained. Our results agree with prior assignments of dipicolinic acid, amino acids and calcium complex ions made in the spore mass spectra. Identity of several previously unidentified mass peaks, key to recognition of Bacillus spore by matrix-free BAMS, is revealed. Specifically, a set of fragment peaks in the negative polarity is shown to be consistent with the fragmentation pattern of purine nucleobase containing compounds. The identity of m/z=+74, a marker peak that helps discriminate Bacillus atrophaeus from Bacillus thuringiensis spores grown in rich medium, is surprisingly a non-description, viz. [N{sub 1}C{sub 4}H{sub 12}]{sup +}. A probable precursor molecule for the [N{sub 1}C{sub 4}H{sub 12}]{sup +} ion observed in spore spectra is trimethyl glycine ({sup +}N(CH{sub 3}){sub 3}CH{sub 2}COOH) that produces a m/z=74 peak in presence of dipicolinic acid.

  19. Using CFD Surface Solutions to Shape Sonic Boom Signatures Propagated from Off-Body Pressure

    Science.gov (United States)

    Ordaz, Irian; Li, Wu

    2013-01-01

    The conceptual design of a low-boom and low-drag supersonic aircraft remains a challenge despite significant progress in recent years. Inverse design using reversed equivalent area and adjoint methods have been demonstrated to be effective in shaping the ground signature propagated from computational fluid dynamics (CFD) off-body pressure distributions. However, there is still a need to reduce the computational cost in the early stages of design to obtain a baseline that is feasible for low-boom shaping, and in the search for a robust low-boom design over the entire sonic boom footprint. The proposed design method addresses the need to reduce the computational cost for robust low-boom design by using surface pressure distributions from CFD solutions to shape sonic boom ground signatures propagated from CFD off-body pressure.

  20. Galileo's Multiinstrument Spectral View of Europa's Surface Composition

    Science.gov (United States)

    Fanale, F.P.; Granahan, J.C.; McCord, T.B.; Hansen, G.; Hibbitts, C.A.; Carlson, R.; Matson, D.; Ocampo, A.; Kamp, L.; Smythe, W.; Leader, F.; Mehlman, R.; Greeley, R.; Sullivan, R.; Geissler, P.; Barth, C.; Hendrix, A.; Clark, B.; Helfenstein, P.; Veverka, J.; Belton, M.J.S.; Becker, K.; Becker, T.

    1999-01-01

    We have combined spectral reflectance data from the Solid State Imaging (SSI) experiment, the Near-Infrared Mapping Spectrometer (NIMS), and the Ultraviolet Spectrometer (UVS) in an attempt to determine the composition and implied genesis of non-H2O components in the optical surface of Europa. We have considered four terrains: (1) the "dark terrains" on the trailing hemisphere, (2) the "mottled terrain," (3) the linea on the leading hemisphere, and (4) the linea embedded in the dark terrain on the trailing hemisphere. The darker materials in these terrains exhibit remarkably similar spectra in both the visible and near infrared. In the visible, a downturn toward shorter wavelengths has been attributed to sulfur. The broad concentrations of dark material on the trailing hemisphere was originally thought to be indicative of exogenic sulfur implantation. While an exogenic cause is still probable, more recent observations by the UVS team at higher spatial resolution have led to their suggestions that the role of the bombardment may have primarily been to sputter away overlying ice and to reveal underlying endogenic non-H2O contaminants. If so, this might explain why the spectra in all these terrains are so similar despite the fact that the contaminants in the linea are clearly endogenic and those in the mottled terrain are almost certainly so. In the near infrared, all these terrains exhibit much more asymmetrical bands at 1.4 and 2.0 ??m at shorter wavelengths than spectra from elsewhere on Europa. It has been argued that this is because the water molecules are bound in hydrated salts. However, this interpretation has been challenged and it has also been argued that pure coarse ice can exhibit such asymmetric bands under certain conditions. The nature of this controversy is briefly discussed, as are theoretical and experimental studies bearing on this problem. ?? 1999 Academic Press.

  1. ARM Climate Research Facility Spectral Surface Albedo Value-Added Product (VAP) Report

    Energy Technology Data Exchange (ETDEWEB)

    McFarlane, S; Gaustad, K; Long, C; Mlawer, E

    2011-07-15

    This document describes the input requirements, output data products, and methodology for the Spectral Surface Albedo (SURFSPECALB) value-added product (VAP). The SURFSPECALB VAP produces a best-estimate near-continuous high spectral resolution albedo data product using measurements from multifilter radiometers (MFRs). The VAP first identifies best estimates for the MFR downwelling and upwelling shortwave irradiance values, and then calculates narrowband spectral albedo from these best-estimate irradiance values. The methodology for finding the best-estimate values is based on a simple process of screening suspect data and backfilling screened and missing data with estimated values when possible. The resulting best-estimate MFR narrowband spectral albedos are used to determine a daily surface type (snow, 100% vegetation, partial vegetation, or 0% vegetation). For non-snow surfaces, a piecewise continuous function is used to estimate a high spectral resolution albedo at 1 min temporal and 10 cm-1 spectral resolution.

  2. ARM Climate Research Facility Spectral Surface Albedo Value-Added Product (VAP) Report

    Energy Technology Data Exchange (ETDEWEB)

    McFarlane, S; Gaustad, K; Long, C; Mlawer, E

    2011-07-15

    This document describes the input requirements, output data products, and methodology for the Spectral Surface Albedo (SURFSPECALB) value-added product (VAP). The SURFSPECALB VAP produces a best-estimate near-continuous high spectral resolution albedo data product using measurements from multifilter radiometers (MFRs). The VAP first identifies best estimates for the MFR downwelling and upwelling shortwave irradiance values, and then calculates narrowband spectral albedo from these best-estimate irradiance values. The methodology for finding the best-estimate values is based on a simple process of screening suspect data and backfilling screened and missing data with estimated values when possible. The resulting best-estimate MFR narrowband spectral albedos are used to determine a daily surface type (snow, 100% vegetation, partial vegetation, or 0% vegetation). For non-snow surfaces, a piecewise continuous function is used to estimate a high spectral resolution albedo at 1 min temporal and 10 cm-1 spectral resolution.

  3. An Airborne Campaign Measuring Wind Signatures from the Sea Surface using an L-band Polarimetric Radiometer

    DEFF Research Database (Denmark)

    Søbjærg, Sten Schmidl; Skou, Niels

    2003-01-01

    A series of circle flights have been carried out over the sea surface, using the EMIRAD L-band polarimetric radiometer. Motion compensation is applied, and polarimetric azimuth signatures are generated. Single tracks show geophysical noise, typically about 2 K, but averaging decreases the noise, ......, but a comparison of the signature to the downwelling galactic background radiation indicates, that the signature may not origin from the wind driven sea surface pattern.......A series of circle flights have been carried out over the sea surface, using the EMIRAD L-band polarimetric radiometer. Motion compensation is applied, and polarimetric azimuth signatures are generated. Single tracks show geophysical noise, typically about 2 K, but averaging decreases the noise...

  4. Simultaneous physical retrieval of surface emissivity spectrum and atmospheric parameters from infrared atmospheric sounder interferometer spectral radiances.

    Science.gov (United States)

    Masiello, Guido; Serio, Carmine

    2013-04-10

    The problem of simultaneous physical retrieval of surface emissivity, skin temperature, and temperature, water-vapor, and ozone atmospheric profiles from high-spectral-resolution observations in the infrared is formulated according to an inverse problem with multiple regularization parameters. A methodology has been set up, which seeks an effective solution to the inverse problem in a generalized L-curve criterion framework. The a priori information for the surface emissivity is obtained on the basis of laboratory data alone, and that for the atmospheric parameters by climatology or weather forecasts. To ensure that we deal with a problem of fewer unknowns than observations, the dimensionality of the emissivity is reduced through expansion in Fourier series. The main objective of this study is to demonstrate the simultaneous retrieval of emissivity, skin temperature, and atmospheric parameters with a two-dimensional L-curve criterion. The procedure has been demonstrated with spectra observed from the infrared atmospheric sounder interferometer, flying onboard the European Meteorological Operational satellite. To check the quality and reliability of the methodology, we have used spectra recorded over regions characterized by known or stable emissivity. These include sea surface, for which effective emissivity models are known, and arid lands (Sahara and Namib Deserts) that are known to exhibit the characteristic spectral signature of quartz-rich sand.

  5. Spectral emissivity measurements of land-surface materials and related radiative transfer simulations

    Science.gov (United States)

    Wan, Z.; Ng, D.; Dozier, J.

    1994-01-01

    Spectral radiance measurements have been made in the laboratory and in the field for deriving spectral emissivities of some land cover samples with a spectroradiometer and an auxiliary radiation source in the wavelength range 2.5-14.5 micrometers. A easy and quick four-step method (four steps to measure the sample and a diffuse reflecting plate surface under sunshine and shadowing conditions, respectively) has been used for simultaneous determination of surface temperature and emissivity. We emphasized in-situ measurements in combination with radiative transfer simulations, and an error analysis for basic assumptions in deriving spectral emissivity of land-surface samples from thermal infrared measurements.

  6. Universal signatures of Fermi arcs in quasiparticle interference on the surface of Weyl semimetals

    Science.gov (United States)

    Kourtis, Stefanos; Li, Jian; Wang, Zhijun; Yazdani, Ali; Bernevig, B. Andrei

    2016-01-01

    Weyl semimetals constitute a newly discovered class of three-dimensional topological materials with linear touchings of valence and conduction bands in the bulk. The most striking property of topological origin in these materials, so far unequivocally observed only in photoemission experiments, is the presence of open constant-energy contours at the boundary— the so-called Fermi arcs. In this Rapid Communication, we establish the universal characteristics of Fermi-arc contributions to surface quasiparticle interference. Using a general phenomenological model, we determine the defining interference patterns stemming from the existence of Fermi arcs in a surface band structure. We then trace these patterns in both simple tight-binding models and realistic ab initio calculations. Our results show that definitive signatures of Fermi arcs can be observed in existing and proposed Weyl semimetals using scanning tunneling spectroscopy.

  7. Spectral signatures of the ionospheric Alfvén resonator to be observed by low-Earth orbit satellite

    Science.gov (United States)

    Surkov, V. V.; Pilipenko, V. A.

    2016-03-01

    Interference of an incident and reflected Alfvén pulses propagating inside the ionospheric Alfvén resonator (IAR) is studied on the basis of a simple one-dimensional model. Particular emphasis has been placed on the analysis of spectral features of ultralow frequency (˜1-15 Hz) electric perturbations recently observed by Communications/Navigation Outage Forecasting System satellite. This "fingerprint" multiband spectral structure was observed when satellite descended in the terminator vicinity. Among factors affecting spectral structure the satellite position and distance from the IAR boundaries are most significant. It is concluded that the observed spectrograms exhibit modulation with "period" depending on propagation delay time of reflected Alfvén pulses in such a way that this effect can mask a spectral resonance structure resulted from excitation of IAR eigenmodes. The proposed interference effect is capable to produce a spectral pattern resembling a fingerprint which is compatible with the satellite observations.

  8. Dynamic changes in spectral and spatial signatures of high frequency oscillations in rat hippocampi during epileptogenesis in acute and chronic stages

    Directory of Open Access Journals (Sweden)

    Pan-Pan Song

    2016-11-01

    Full Text Available Objective: To analyze spectral and spatial signatures of high frequency oscillations (HFOs, which include ripples and fast ripples (FRs, > 200 Hz by quantitatively assessing average and peak spectral power in a rat model of different stages of epileptogenesis.Methods: The lithium–pilocarpine model of temporal lobe epilepsy was used. The acute phase of epilepsy was assessed by recording intracranial electroencephalography (EEG activity for 1 day after status epilepticus (SE. The chronic phase of epilepsy, including spontaneous recurrent seizures (SRSs, was assessed by recording EEG activity for 28 days after SE. Average and peak spectral power of five frequency bands of EEG signals in CA1, CA3 and DG regions of the hippocampus were analyzed with wavelet and digital filter.Results: FRs occurred in the hippocampus in the animal model. Significant dynamic changes in the spectral power of FRS were identified in CA1 and CA3. The average spectral power of ripples increased at 20 min before SE (p < 0.05, peaked at 10 min before diazepam injection. It decreased at 10 min after diazepam (p < 0.05 and returned to baseline after 1 hour (h. The average spectral power of FRs increased at 30 min before SE (p < 0.05 and peaked at 10 min before diazepam. It decreased at 10 min after diazepam (p < 0.05 and returned to baseline at 2 h after injection. The dynamic changes were similar between average and peak spectral power of FRs. Average and peak spectral power of both ripples and FRs in the chronic phase showed a gradual downward trend compared with normal rats 14 days after SE.Significance: The spectral power of HFOs may be utilized to distinguish between normal and pathologic HFOs. Ictal average and peak spectral power of FRs were two parameters for predicting acute epileptic seizures, which could be used as a new quantitative biomarker and early warning marker of seizure. Changes in interictal HFOs power in the hippocampus at the chronic stage may be not

  9. Mapping of Surface and Shallow Subsurface Signatures in the CONSERT Data during the Descent of Philae

    Science.gov (United States)

    Plettemeier, Dirk; Statz, Christoph; Hahnel, Ronny; Hegler, Sebastian; Kofman, Wlodek; Herique, Alain; Rogez, Yves; Pasquero, Pierre; Zine, Sonia; Ciarletti, Valerie

    2016-04-01

    The primary scientific objective of the Comet Nucleus Sounding Experiment by Radiowave Transmission (CONSERT) aboard Rosetta is the characterization of comet 67P/Chuyurmov-Gerasimenko's deep interior dielectric properties. This was done during the first science sequence (FSS) by means of bi-static radio propagation measurements between the the CONSERT instrument aboard lander Philae launched onto the comet's surface and its counterpart aboard the Rosetta orbiter. In addition to the FSS measurements, CONSERT was operated during the separation and descent of Philae onto the 67P/C-G's surface. The received CONSERT signal during the SDL consists of the direct propagation between Rosetta and Philae and indirect reflections of 67P/C-G's surface. Using the peak power measurements in the dominant direct path between Rosetta and Philae during the descent we were able to reconstruct the lander's attitude and estimate the spin rate of the lander along its descent trajectory. The deployment of the lander legs and CONSERT antennas as well as the orbiter change of attitude in order to orient the science towards the assumed lander position are visible in the measured CONSERT data as well. The information gained on Philae's attitude is used in the estimation of 67P/C-G's surface and near subsurface dielectric properties. Information on the surface of 67P/C-G are contained in the data during roughly the last third of the descent of Philae onto the comet's surface. The surface signatures in the measured data are mapped to the location of origin on 67P/C-G's surface. The results from the mapping process show good spatial diversity along the descent track of Philae necessary for the estimation of the dielectric properties of prominent features in the CONSERT SDL data.

  10. Investigating the effect of electro-active ion concentration on spectral induced polarization signatures arising from biomineralization pathways

    Science.gov (United States)

    Ntarlagiannis, D.; Slater, L. D.; Williams, K. H.; Hubbard, S. S.; Wu, Y.

    2010-12-01

    Spectral induced polarization (SIP) is a proven geophysical method for detecting biomineral formation with promising applications for monitoring biogeochemical products during microbial induced sequestration of heavy metals and radionuclides in soils. SIP has been used to monitor the evolution of bioremediation-induced end-products at the uranium-contaminated U.S. Department of Energy Rifle Integrated Field Research Challenge site in Colorado. Although a significant SIP response was detected, the quantitative interpretation is non-trivial as the polarization of metallic minerals depends both on the mineral surface properties and the electrolyte chemistry. In previous experiments SIP mechanisms were studied under complex environments and individual source mechanisms could not be evaluated. Here we examine the role of electrolyte chemistry by comparing the effect of redox active / inactive ions on metallic polarization. In these abiotic experiments magnetite was used as a proxy biomineral and dispersed within columns packed with sand. Parallel columns were saturated with solutions of different concentrations of active (Fe2+) and inactive (Ca2+) ions (0.01mM-10mM) and SIP measurements made (0.1-1000 Hz). Experimental results show small, but detectable, differences in the effect of active ion and inactive ion concentration on the SIP response. To better characterize the effect of electro-active ions on metallic minerals we used a Cole - Cole type relaxation model, to describe the SIP responses. In order to better resolve the relaxation model parameters, we followed a two-step approach whereby we started with a Bayesian based inversion to resolve for the initial parameter estimates, and subsequently used these estimates as a starting model for a deterministic solution. Our results suggest that changes in the active ion concentration, in the presence of magnetite, alone are unlikely to fully explain recent SIP monitoring data from the Rifle site.

  11. Surface signature of Mediterranean water eddies in the North-East Atlantic: effect of the upper ocean stratification

    Directory of Open Access Journals (Sweden)

    I. Bashmachnikov

    2012-07-01

    Full Text Available Meddies, intra-thermocline eddies of Mediterranean water, are often visible at the sea surface as positive sea-level anomalies. Here we study the surface signature of several meddies tracked with RAFOS floats and AVISO altimetry. Then, theoretical estimates of the surface signature of a meddy are derived, based on geostrophy and potential vorticity balance. The intensity of the surface signature is proportional to the meddy core radius and to the Coriolis parameter, and inversely proportional to the core depth and buoyancy frequency. This indicates that surface signature of a meddy may be strongly reduced by the upper ocean stratification. Estimates suggest that the southernmost limit for detection in altimetry of small meddies (with radii on the order of 15 km should lie in the northern subtropics, while large meddies (with radii of 25–30 km could be detected as far south as the northern tropics. During the initial period of meddy acceleration after meddy formation or a stagnation stage, a cyclonic signal also is generated at the sea-surface, but mostly the anticyclonic surface signal follows the meddy.

  12. Single particle mass spectral signatures from vehicle exhaust particles and the source apportionment of on-line PM2.5 by single particle aerosol mass spectrometry.

    Science.gov (United States)

    Yang, Jian; Ma, Shexia; Gao, Bo; Li, Xiaoying; Zhang, Yanjun; Cai, Jing; Li, Mei; Yao, Ling'ai; Huang, Bo; Zheng, Mei

    2017-09-01

    In order to accurately apportion the many distinct types of individual particles observed, it is necessary to characterize fingerprints of individual particles emitted directly from known sources. In this study, single particle mass spectral signatures from vehicle exhaust particles in a tunnel were performed. These data were used to evaluate particle signatures in a real-world PM2.5 apportionment study. The dominant chemical type originating from average positive and negative mass spectra for vehicle exhaust particles are EC species. Four distinct particle types describe the majority of particles emitted by vehicle exhaust particles in this tunnel. Each particle class is labeled according to the most significant chemical features in both average positive and negative mass spectral signatures, including ECOC, NaK, Metal and PAHs species. A single particle aerosol mass spectrometry (SPAMS) was also employed during the winter of 2013 in Guangzhou to determine both the size and chemical composition of individual atmospheric particles, with vacuum aerodynamic diameter (dva) in the size range of 0.2-2μm. A total of 487,570 particles were chemically analyzed with positive and negative ion mass spectra and a large set of single particle mass spectra was collected and analyzed in order to identify the speciation. According to the typical tracer ions from different source types and classification by the ART-2a algorithm which uses source fingerprints for apportioning ambient particles, the major sources of single particles were simulated. Coal combustion, vehicle exhaust, and secondary ion were the most abundant particle sources, contributing 28.5%, 17.8%, and 18.2%, respectively. The fraction with vehicle exhaust species particles decreased slightly with particle size in the condensation mode particles. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Inference of Surface Chemical and Physical Properties Using Mid-Infrared (MIR) Spectral Observations

    Science.gov (United States)

    Roush, Ted L.

    2016-01-01

    Reflected or emitted energy from solid surfaces in the solar system can provide insight into thermo-physical and chemical properties of the surface materials. Measurements have been obtained from instruments located on Earth-based telescopes and carried on several space missions. The characteristic spectral features commonly observed in Mid-Infrared (MIR) spectra of minerals will be reviewed, along with methods used for compositional interpretations of MIR emission spectra. The influence of surface grain size, and space weathering processes on MIR emissivity spectra will also be discussed. Methods used for estimating surface temperature, emissivity, and thermal inertias from MIR spectral observations will be reviewed.

  14. UV spectral filtering by surface structured multilayer mirrors

    NARCIS (Netherlands)

    Huang, Q.; Paardekooper, Daniel Mathijs; Zoethout, E.; Medvedev, V. V.; van de Kruijs, Robbert; Bosgra, Jeroen; Louis, Eric; F. Bijkerk,

    2014-01-01

    A surface structured extreme ultraviolet multilayer mirror was developed showing full band suppression of UV (lambda = 100-400 nm) and simultaneously a high reflectance of EUV light (lambda = 13.5 nm). The surface structure consists of Si pyramids, which are substantially transparent for EUV but

  15. UV spectral filtering by surface structured multilayer mirrors

    NARCIS (Netherlands)

    Huang, Q.; Paardekooper, Daniel Mathijs; Zoethout, E.; Medvedev, V. V.; van de Kruijs, Robbert; Bosgra, Jeroen; Louis, Eric; F. Bijkerk,

    2014-01-01

    A surface structured extreme ultraviolet multilayer mirror was developed showing full band suppression of UV (lambda = 100-400 nm) and simultaneously a high reflectance of EUV light (lambda = 13.5 nm). The surface structure consists of Si pyramids, which are substantially transparent for EUV but ref

  16. Spectral reflectance of surface soils - A statistical analysis

    Science.gov (United States)

    Crouse, K. R.; Henninger, D. L.; Thompson, D. R.

    1983-01-01

    The relationship of the physical and chemical properties of soils to their spectral reflectance as measured at six wavebands of Thematic Mapper (TM) aboard NASA's Landsat-4 satellite was examined. The results of performing regressions of over 20 soil properties on the six TM bands indicated that organic matter, water, clay, cation exchange capacity, and calcium were the properties most readily predicted from TM data. The middle infrared bands, bands 5 and 7, were the best bands for predicting soil properties, and the near infrared band, band 4, was nearly as good. Clustering 234 soil samples on the TM bands and characterizing the clusters on the basis of soil properties revealed several clear relationships between properties and reflectance. Discriminant analysis found organic matter, fine sand, base saturation, sand, extractable acidity, and water to be significant in discriminating among clusters.

  17. Phonon spectral densities of Cu surfaces: Application to Cu(211)

    Science.gov (United States)

    Mărinică, M.-C.; Raşeev, G.; Smirnov, K. S.

    2001-05-01

    Power phonon spectra of vicinal stepped surfaces of Cu(211) have been calculated using a molecular dynamics method combined with a semiempirical potential. The potential is based on an analytic form of inverse powers proposed by Finnis and Sinclair with the parametrization of Sutton and Chen. One of the four independent parameters of the potential was rescaled to reproduce the bulk phonon spectrum of Cu while retaining other properties of the bulk Cu close to the experimental values. Using this potential, we calculated the power surface phonon spectra, projection of the spectra at the high-symmetry points of surface Brillouin zone (SBZ), and the mean square displacements (MSD's) of atoms of the Cu(211) surface. The calculated projected phonon spectra at Γ¯ and at two new SBZ points (at X¯ and Y¯) compare favorably with experiment and theory when available. The MSD of the Cu(211) surface is also well reproduced and its temperature dependence shows that anharmonicity of the atomic motion becomes important above 200 K.

  18. Stratified spectral mixture analysis of medium resolution imagery for impervious surface mapping

    Science.gov (United States)

    Sun, Genyun; Chen, Xiaolin; Ren, Jinchang; Zhang, Aizhu; Jia, Xiuping

    2017-08-01

    Linear spectral mixture analysis (LSMA) is widely employed in impervious surface estimation, especially for estimating impervious surface abundance in medium spatial resolution images. However, it suffers from a difficulty in endmember selection due to within-class spectral variability and the variation in the number and the type of endmember classes contained from pixel to pixel, which may lead to over or under estimation of impervious surface. Stratification is considered as a promising process to address the problem. This paper presents a stratified spectral mixture analysis in spectral domain (Sp_SSMA) for impervious surface mapping. It categorizes the entire data into three groups based on the Combinational Build-up Index (CBI), the intensity component in the color space and the Normalized Difference Vegetation Index (NDVI) values. A suitable endmember model is developed for each group to accommodate the spectral variation from group to group. The unmixing into the associated subset (or full set) of endmembers in each group can make the unmixing adaptive to the types of endmember classes that each pixel actually contains. Results indicate that the Sp_SSMA method achieves a better performance than full-set-endmember SMA and prior-knowledge-based spectral mixture analysis (PKSMA) in terms of R, RMSE and SE.

  19. Spectral features in isolated neutron stars induced by inhomogeneous surface temperatures

    CERN Document Server

    Viganò, Daniele; Rea, Nanda; Pons, José A

    2014-01-01

    The thermal X-ray spectra of several isolated neutron stars display deviations from a pure blackbody. The accurate physical interpretation of these spectral features bears profound implications for our understanding of the atmospheric composition, magnetic field strength and topology, and equation of state of dense matter. With specific details varying from source to source, common explanations for the features have ranged from atomic transitions in the magnetized atmospheres or condensed surface, to cyclotron lines generated in a hot ionized layer near the surface. Here we quantitatively evaluate the X-ray spectral distortions induced by inhomogeneous temperature distributions of the neutron star surface. To this aim, we explore several surface temperature distributions, we simulate their corresponding general relativistic X-ray spectra (assuming an isotropic, blackbody emission), and fit the latter with a single blackbody model. We find that, in some cases, the presence of a spurious 'spectral line' is requ...

  20. Spectral Signature of Column Solar Radiation Absorption During the Atmospheric Radiation Measurement Enhanced Shortwave Experiment (ARESE). Revision

    Energy Technology Data Exchange (ETDEWEB)

    O' Hirok, William; Gautier, Catherine; Ricchiazzi, Paul

    1999-11-01

    Spectral and broadband shortwave radiative flux data obtained from the Atmospheric Radiation Measurement Enhanced Shortwave Experiment (ARESE) are compared with 3-D radiative transfer computations for the cloud field of October 30, 1995. Because the absorption of broadband solar radiation in the cloudy atmosphere deduced from observations and modeled differ by 135 Wm{sup -2}, we performed a consistency analysis using spectral observations and the model to integrate for wavelengths between the spectral observations. To match spectral measurements, aerosols need a reduction in both single scattering albedo (from 0.938 to 0.82) and asymmetry factor (from 0.67 to 0.61), and cloud droplets require a three-fold increase in co-albedo. Even after modifying the model inputs and microphysics the difference in total broadband absorption is still of the order of 75Wm{sup -2}. Finally, an unexplained absorber centered around 1.06 {micro}m appears in the comparison that is much too large to be explained by dimers.

  1. Variation of surface water spectral response as a function of in situ sampling technique

    Science.gov (United States)

    Davis, Bruce A.; Hodgson, Michael E.

    1988-01-01

    Tests were carried out to determine the spectral variation contributed by a particular sampling technique. A portable radiometer was used to measure the surface water spectral response. Variation due to the reflectance of objects near the radiometer (i.e., the boat side) during data acquisition was studied. Consideration was also given to the variation due to the temporal nature of the phenomena (i.e., wave activity).

  2. Multivariate Statistical Analysis of Orthogonal Mass Spectral Data for the Identification of Chemical Attribution Signatures of 3-Methylfentanyl

    Energy Technology Data Exchange (ETDEWEB)

    Mayer, B. P. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Valdez, C. A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); DeHope, A. J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Spackman, P. E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Sanner, R. D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Martinez, H. P. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Williams, A. M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-11-28

    Critical to many modern forensic investigations is the chemical attribution of the origin of an illegal drug. This process greatly relies on identification of compounds indicative of its clandestine or commercial production. The results of these studies can yield detailed information on method of manufacture, sophistication of the synthesis operation, starting material source, and final product. In the present work, chemical attribution signatures (CAS) associated with the synthesis of the analgesic 3- methylfentanyl, N-(3-methyl-1-phenethylpiperidin-4-yl)-N-phenylpropanamide, were investigated. Six synthesis methods were studied in an effort to identify and classify route-specific signatures. These methods were chosen to minimize the use of scheduled precursors, complicated laboratory equipment, number of overall steps, and demanding reaction conditions. Using gas and liquid chromatographies combined with mass spectrometric methods (GC-QTOF and LC-QTOF) in conjunction with inductivelycoupled plasma mass spectrometry (ICP-MS), over 240 distinct compounds and elements were monitored. As seen in our previous work with CAS of fentanyl synthesis the complexity of the resultant data matrix necessitated the use of multivariate statistical analysis. Using partial least squares discriminant analysis (PLS-DA), 62 statistically significant, route-specific CAS were identified. Statistical classification models using a variety of machine learning techniques were then developed with the ability to predict the method of 3-methylfentanyl synthesis from three blind crude samples generated by synthetic chemists without prior experience with these methods.

  3. Herschel/HIFI observations of spectrally resolved methylidyne signatures toward the high-mass star forming core NGC6334I

    CERN Document Server

    van der Wiel, M H D; Lis, D C; Bergin, E A; Comito, C; Emprechtinger, M; Schilke, P; Caux, E; Ceccarelli, C; Baudry, A; Goldsmith, P F; Herbst, E; Langer, W; Lord, S; Neufeld, D; Pearson, J; Philips, T; Rolffs, R; Yorke, H; Bacmann, A; Benedettini, M; Blake, G A; Boogert, A; Bottinelli, S; Cabrit, S; Caselli, P; Castets, A; Cernicharo, J; Codella, C; Coutens, A; Crimier, N; Demyk, K; Dominik, C; Encrenaz, P; Falgarone, E; Fuente, A; Gerin, M; Helmich, F; Hennebelle, P; Henning, T; Hily-Blant, P; Jacq, T; Kahane, C; Kama, M; Klotz, A; Lefloch, B; Lorenzani, A; Maret, S; Melnick, G; Nisini, B; Pacheco, S; Pagani, L; Parise, B; Salez, M; Saraceno, P; Schuster, K; Tielens, A G G M; Vastel, C; Viti, S; Wakelam, V; Walters, A; Wyrowski, F; Edwards, K; Zmuidzinas, J; Morris, P; Samoska, L A; Teyssier, D

    2010-01-01

    In contrast to extensively studied dense star forming cores, little is known about diffuse gas surrounding star forming regions. We aim to study molecular gas in the high-mass star forming region NGC6334I, including diffuse, quiescent components which are inconspicuous in widely used molecular tracers such as CO. We present Herschel/HIFI observations of CH toward NGC6334I observed as part of the CHESS Key Program. HIFI resolves the hyperfine components of its J=3/2-1/2 transition, observed in emission as well as in absorption. The CH emission appears close to the systemic velocity of NGC6334I, while a linewidth of 3 km/s is smaller than previously observed in dense gas tracers such as NH3 and SiO. The CH abundance in the hot core is 7 10^-11, two to three orders of magnitude lower than in diffuse clouds. While other studies find distinct outflows in, e.g., CO and H2O toward NGC6334I, we do not detect outflow signatures in CH. To explain the absorption signatures, at least two absorbing components are needed a...

  4. Theoretical and Experimental Study of Spectral Selectivity Surface for Both Solar Heating and Radiative Cooling

    Directory of Open Access Journals (Sweden)

    Mingke Hu

    2015-01-01

    Full Text Available A spectral selectivity surface for both solar heating and radiative cooling was proposed. It has a high spectral absorptivity (emissivity in the solar radiation band and atmospheric window band (i.e., 0.2~3 μm and 8~13 μm, as well as a low absorptivity (emissivity in other bands aside from the solar radiation and atmospheric window wavelengths (i.e., 3~8 μm or above 13 μm. A type of composite surface sample was trial-manufactured combining titanium-based solar selective absorbing coating with polyethylene terephthalate (TPET. Sample tests showed that the TPET composite surface has clear spectral selectivity in the spectra of solar heating and radiation cooling wavelengths. The equilibrium temperatures of the TPET surface under different sky conditions or different inclination angles of surface were tested at both day and night. Numerical analysis and comparisons among the TPET composite surface and three other typical surfaces were also performed. These comparisons indicated that the TPET composite surface had a relative heat efficiency of 76.8% of that of the conventional solar heating surface and a relative temperature difference of 75.0% of that of the conventional radiative cooling surface, with little difference in cooling power.

  5. Retrieving the availability of light in the ocean utilising spectral signatures of Vibrational Raman Scattering in hyper-spectral satellite measurements

    Directory of Open Access Journals (Sweden)

    T. Dinter

    2015-01-01

    et al., 2014. RTM simulations for different chlorophyll a concentrations and illumination conditions clearly show, that low fit factors of VRS retrieval results correspond to low amounts of light in the water column and vice versa. Exemplary, one month of SCIAMACHY data were processed and a global map of the depth integrated scalar irradiance E0 was retrieved. Spectral structures of VRS were clearly identified in the radiance measurements of SCIAMACHY. The fitting approach led to consistent results and the WF-DOAS algorithm results of VRS correlated clearly with the chlorophyll concentration in case-I water. Comparisons of the diffuse attenuation coefficient, extracted by VRS fit results, with the established GlobColour Kd (490 product show consistent results.

  6. Unravelling remote sensing signatures of plants contaminated with gasoline and diesel: an approach using the red edge spectral feature.

    Science.gov (United States)

    Sanches, I D; Souza Filho, C R; Magalhães, L A; Quitério, G C M; Alves, M N; Oliveira, W J

    2013-03-01

    Pipeline systems used to transport petroleum products represent a potential source of soil pollution worldwide. The design of new techniques that may improve current monitoring of pipeline leakage is imperative. This paper assesses the remote detection of small leakages of liquid hydrocarbons indirectly, through the analysis of spectral features of contaminated plants. Leaf and canopy spectra of healthy plants were compared to spectra of plants contaminated with diesel and gasoline, at increasing rates of soil contamination. Contamination effects were observed both visually in the field and thorough changes in the spectral reflectance patterns of vegetation. Results indicate that the remote detection of small volumes of gasoline and diesel contaminations is feasible based on the red edge analysis of leaf and canopy spectra of plants. Brachiaria grass ranks as a favourable choice to be used as an indicator of HCs leakages along pipelines. Copyright © 2012 Elsevier Ltd. All rights reserved.

  7. Determination of the Wenzel roughness parameter by the Power Spectral Density of functional Alumina surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Jardim, P.L.G., E-mail: pedro.lovato@ufrgs.br [Programa de Pós-Graduação em Microeletrônica, Instituto de Física da Universidade Federal do Rio Grande do Sul, CEP. 91501-970 Porto Alegre (Brazil); Horowitz, F. [Programa de Pós-Graduação em Microeletrônica, Instituto de Física da Universidade Federal do Rio Grande do Sul, CEP. 91501-970 Porto Alegre (Brazil); Felde, N.; Schröder, S.; Coriand, L.; Duparré, A. [Fraunhofer Institute for Applied Optics and Precision Engineering, D 07745 Jena (Germany)

    2016-05-01

    The Wenzel roughness parameter of isotropic Gaussian surfaces is analytically described in terms of the Power Spectral Density function without the smooth surface approximation. This Wenzel roughness parameter — Power Spectral Density link was examined for distinct roughnesses of Aluminum-oxide thin films. The Power Spectral Density functions of the surfaces were determined in a wide spatial frequency range by combining different scan areas of Atomic Force Microscopy measurements. The calculated results presented a good agreement with the Wenzel roughness parameter values obtained directly from the topography measured by Atomic Force Microscopy. Finally, wetting behavior was ascertained through determination of water contact angles, including superhydrophobic behavior. This approach, together with an empirical procedure based on a structural parameter, can predict the wetting properties of a surface by taking all its relevant roughness components into account. - Highlights: • Wenzel roughness parameter and Power Spectral Density are theoretically linked. • The formula is tested for Alumina surfaces with distinct roughnesses. • The formula agrees with the experimental data from Atomic Force Microscopy. • The proper contribution of topography in surface wetting can be ascertained.

  8. Time-Delay Signature of Chaotic Vertical-Cavity Surface-Emitting Lasers with Polarization-Rotated Optical Feedback

    Institute of Scientific and Technical Information of China (English)

    XIANG Shui-Ying; PAN Wei; YAN Lian-Shan; LUO Bin; ZOU Xi-Hua; JIANG Ning; WEN Kun-Hua

    2011-01-01

    To quantitatively evaluate the time-delay (TD) signatures of chaotic signals generated by vertical-cavity surface-emitting lasers (VCSELs) with polarization-rotated optical feedback (PROF), we propose four cases of resolution coefficients R based on correlation functions. The resolution coefficient characteristics for the x-polarization (XP) mode, y-polarization (YP) mode and the total output are considered. The dependences of R on the feedback strength and feedback delay are discussed and compared carefully. The two-dimensional maps of R show that the TD signatures for the single polarization mode (I.e., XP or YP mode) are much more difficult to retrieve than those for the total output in the entire parameter space. Thus, by using single polarization mode as a chaotic carrier, the TD signatures are extremely difficult to be identified, which contributes a lot in the security-enhanced VCSELs-based chaotic optical communication systems.

  9. Retrieving the availability of light in the ocean utilising spectral signatures of Vibrational Raman Scattering in hyper-spectral satellite measurements

    Science.gov (United States)

    Dinter, T.; Rozanov, V. V.; Burrows, J. P.; Bracher, A.

    2015-01-01

    The availability of light in the ocean is an important parameter for the determination of phytoplankton photosynthesis processes and primary production from satellite data. It is also a useful parameter for other applications, e.g. the determination of heat fluxes. In this study, a method was developed utilising the vibrational Raman scattering (VRS) effect of water molecules to determine the amount of photons available in the ocean water, which is expressed by the depth integrated scalar irradiance text-decoration:overline">E0. Radiative transfer simulations with the fully coupled ocean-atmosphere Radiative Transfer Model (RTM) SCIATRAN show clearly the relationship of text-decoration:overline">E0 to the strength of the VRS signal measured at the top of the atmosphere (TOA). Taking advantage of VRS structures in hyper-spectral satellite measurements a retrieval technique to derive text-decoration:overline"> E0 in the wavelength region from 390 to 444.5 nm was developed. This approach uses the Weighting Function Differential Optical Absorption Spectroscopy (WF-DOAS) technique, applied to TOA radiances, measured by the Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY). Based on the approach of Vountas et al. (2007), where the DOAS method was used to fit modelled spectra of VRS, the method was improved by using the weighting function of VRS (VRS-WF) in the DOAS fit. This was combined with a look-up table (LUT) technique, where the text-decoration:overline"> E0 value was obtained for each VRS satellite fit directly. The VRS-WF and the LUT were derived from calculations with the RTM SCIATRAN (Rozanov et al., 2014). RTM simulations for different chlorophyll a concentrations and illumination conditions clearly show, that low fit factors of VRS retrieval results correspond to low amounts of light in the water column and vice versa. Exemplary, one month of SCIAMACHY data were processed and a global map of the depth integrated scalar

  10. Surface Signature Characterization at SPE through Ground-Proximal Methods: Methodology Change and Technical Justification

    Energy Technology Data Exchange (ETDEWEB)

    Schultz-Fellenz, Emily S. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-09-09

    A portion of LANL’s FY15 SPE objectives includes initial ground-based or ground-proximal investigations at the SPE Phase 2 site. The area of interest is the U2ez location in Yucca Flat. This collection serves as a baseline for discrimination of surface features and acquisition of topographic signatures prior to any development or pre-shot activities associated with SPE Phase 2. Our team originally intended to perform our field investigations using previously vetted ground-based (GB) LIDAR methodologies. However, the extended proposed time frame of the GB LIDAR data collection, and associated data processing time and delivery date, were unacceptable. After technical consultation and careful literature research, LANL identified an alternative methodology to achieve our technical objectives and fully support critical model parameterization. Very-low-altitude unmanned aerial systems (UAS) photogrammetry appeared to satisfy our objectives in lieu of GB LIDAR. The SPE Phase 2 baseline collection was used as a test of this UAS photogrammetric methodology.

  11. A New Algorithm for the Satellite-Based Retrieval of Solar Surface Irradiance in Spectral Bands

    Directory of Open Access Journals (Sweden)

    Annette Hammer

    2012-03-01

    Full Text Available Accurate solar surface irradiance data is a prerequisite for an efficient planning and operation of solar energy systems. Further, it is essential for climate monitoring and analysis. Recently, the demand on information about spectrally resolved solar surface irradiance has grown. As surface measurements are rare, satellite derived information with high accuracy might fill this gap. This paper describes a new approach for the retrieval of spectrally resolved solar surface irradiance from satellite data. The method combines a eigenvector-hybrid look-up table approach for the clear sky case with satellite derived cloud transmission (Heliosat method. The eigenvector LUT approach is already used to retrieve the broadband solar surface irradiance of data sets provided by the Climate Monitoring Satellite Application Facility (CM-SAF. This paper describes the extension of this approach to wavelength bands and the combination with spectrally resolved cloud transmission values derived with radiative transfer corrections of the broadband cloud transmission. Thus, the new approach is based on radiative transfer modeling and enables the use of extended information about the atmospheric state, among others, to resolve the effect of water vapor and ozone absorption bands. The method is validated with spectrally resolved measurements from two sites in Europe and by comparison with radiative transfer calculations. The validation results demonstrate the ability of the method to retrieve accurate spectrally resolved irradiance from satellites. The accuracy is in the range of the uncertainty of surface measurements, with exception of the UV and NIR ( ≥ 1200 nm part of the spectrum, where higher deviations occur.

  12. Local states in one-dimensional CDW (charge density wave) materials: Spectral signatures for polarons and bipolarons in MX chains

    Energy Technology Data Exchange (ETDEWEB)

    Swanson, B. I.; Donohoe, R. J.; Worl, L. A.; Bulou, A. D.F.; Arrington, C. A.; Gammel, J. T.; Saxena, A.; Bishop, A. R.

    1990-01-01

    We have undertaken a combined theoretical and experimental effort directed toward the examination of both the ground and defect states in halide-bridged mixed-valence metal linear chains materials as they are tuned within and between broken symmetry phases. Novel low-dimensional highly correlated electronic materials offer a difficult theoretical challenge as we must span from a description of electronic structure on a molecular scale to the meso scale structure that is intrinsic to these solids. Our theoretical effort at Los Alamos combines quantum chemistry, band structure calculations, and many body modeling using Peierls-Hubbard Hamiltonians in order to model ground and local states. The experimental effort combines synthesis and a variety of microscopic structural and spectroscopic probes and macroscopic measurements in an effort to fully characterize both ground and local states as these materials are tuned in the phase boundary regions between broken symmetry states. The present article summarizes some of our recent research using optical spectroscopy to obtain signatures of photoexcited and intrinsic local states and compares these experimental results with Peierls-Hubbard calculations of the optical properties of these materials. Details concerning the theoretical and experimental approaches can be found elsewhere.

  13. Spectral signatures of intramolecular charge transfer process in beta-enaminones: a combined experimental and theoretical analysis.

    Science.gov (United States)

    Misra, Ramprasad; Mandal, Abhijit; Mukhopadhyay, Madhuri; Maity, D K; Bhattacharyya, S P

    2009-08-06

    In this paper, we present spectroscopic signatures of intramolecular charge transfer (ICT) and effects of solvent on the ICT process in 3-(phenylamino)-2-cyclohexen-1-one (PACO), a member of the well-known molecular family, the beta-enaminones. The dual fluorescence in the steady state emission spectra of the molecule in polar solvents indicates the occurrence of ICT, which is further supported by time-resolved studies, using time correlated single photon counting technique with picosecond resolution. To understand the nature of the charge transfer, pH dependent studies of the probe in water were performed, where a quenching of fluorescence was observed even in the presence of very low concentrations of acids. Solvent induced fluorescence quenching was observed in ethanol and methanol. The ICT process was also investigated by quantum chemical calculations. To understand the role of solvents in the ICT process, we have theoretically studied the macroscopic and microscopic solvation of the probe in water. The absorption spectra of the molecule in the gas phase as well as in water were simulated using time dependent density functional theory with cc-pVTZ basis set and self-consistent reaction field theory that models macroscopic solvation. The possibility of microscopic solvation in water was probed theoretically and the formation of 1:3 molecular clusters by PACO with water molecules has been confirmed. Our findings could have a bearing on pH sensing applications of the probe.

  14. Development of a low-cost, 11 µm spectral domain optical coherence tomography surface profilometry prototype

    Science.gov (United States)

    Suliali, Nyasha J.; Baricholo, Peter; Neethling, Pieter H.; Rohwer, Erich G.

    2017-06-01

    A spectral-domain Optical Coherence Tomography (OCT) surface profilometry prototype has been developed for the purpose of surface metrology of optical elements. The prototype consists of a light source, spectral interferometer, sample fixture and software currently running on Microsoft® Windows platforms. In this system, a broadband light emitting diode beam is focused into a Michelson interferometer with a plane mirror as its sample fixture. At the interferometer output, spectral interferograms of broadband sources were measured using a Czerny-Turner mount monochromator with a 2048-element complementary metal oxide semiconductor linear array as the detector. The software performs importation and interpolation of interferometer spectra to pre-condition the data for image computation. One dimensional axial OCT images were computed by Fourier transformation of the measured spectra. A first reflection surface profilometry (FRSP) algorithm was then formulated to perform imaging of step-function-surfaced samples. The algorithm re-constructs two dimensional colour-scaled slice images by concatenation of 21 and 13 axial scans to form a 10 mm and 3.0 mm slice respectively. Measured spectral interferograms, computed interference fringe signals and depth reflectivity profiles were comparable to simulations and correlated to displacements of a single reflector linearly translated about the arm null-mismatch point. Surface profile images of a double-step-function-surfaced sample, embedded with inclination and crack detail were plotted with an axial resolution of 11 μm. The surface shape, defects and misalignment relative to the incident beam were detected to the order of a micron, confirming high resolution of the developed system as compared to electro-mechanical surface profilometry techniques.

  15. Electronic Warfare Signature Measurement Facility

    Data.gov (United States)

    Federal Laboratory Consortium — The Electronic Warfare Signature Measurement Facility contains specialized mobile spectral, radiometric, and imaging measurement systems to characterize ultraviolet,...

  16. Electronic Warfare Signature Measurement Facility

    Data.gov (United States)

    Federal Laboratory Consortium — The Electronic Warfare Signature Measurement Facility contains specialized mobile spectral, radiometric, and imaging measurement systems to characterize ultraviolet,...

  17. Estimating and Mapping Urban Impervious Surfaces: Reflection on Spectral, Spatial, and Temporal Resolutions

    Science.gov (United States)

    Weng, Q.

    2007-12-01

    Impervious surface is a key indicator of urban environmental quality and urbanization degree. Therefore, estimation and mapping of impervious surfaces in urban areas has attracted more and more attention recently by using remote sensing digital images. In this paper, satellite images with various spectral, spatial, and temporal resolutions are employed to examine the effects of these remote sensing data characteristics on mapping accuracy of urban impervious surfaces. The study area was the city proper of Indianapolis (Marion County), Indiana, United States. Linear spectral mixture analysis was applied to generate high albedo, low albedo, vegetation, and soil fraction images (endmembers) from the satellite images, and impervious surfaces were then estimated by adding high albedo and low albedo fraction images. A comparison of EO-1 ALI (multispectral) and Hyperion (hyperspectral) images indicates that the Hyperion image was more effective in discerning low albedo surface materials, especially the spectral bands in the mid-infrared region. Linear spectral mixing modeling was found more useful for medium spatial resolution images, such as Landsat TM/ETM+ and ASTER images, due to the existence of a large amount of mixed pixels in the urban areas. The model, however, may not be suitable for high spatial resolution images, such as IKONOS images, because of less influence from the mixing pixel. The shadow problem in the high spatial resolution images, caused by tall buildings and large tree crowns, is a challenge in impervious surface extraction. Alternative image processing algorithms such as decision tree classifier may be more appropriate to achieve high mapping accuracy. For mid-latitude cities, seasonal vegetation phenology has a significant effect on the spectral response of terrestrial features, and therefore, image analysis must take into account of this environmental characteristic. Three ASTER images, acquired on April 5, 2004, June 16, 2001, and October 3, 2000

  18. Spectral reflectance properties of minerals exposed to simulated Mars surface conditions

    Science.gov (United States)

    Cloutis, E. A.; Craig, M. A.; Kruzelecky, R. V.; Jamroz, W. R.; Scott, A.; Hawthorne, F. C.; Mertzman, S. A.

    2008-05-01

    A number of mineral species were exposed to martian surface conditions of atmospheric pressure and composition, temperature, and UV light regime, and their evolution was monitored using reflectance spectroscopy. The stabilities for different groups varied widely. Phyllosilicate spectra all showed measurable losses of interlayer H 2O, with some structural groups showing more rapid H 2O loss than others. Loss of OH from the phyllosilicates is not always accompanied by a change in metal-OH overtone absorption bands. OH-bearing sulfates, such as jarosite and alunite, show no measurable change in spectral properties, suggesting that they should be spectrally detectable on Mars on the basis of diagnostic absorption bands in the 0.4-2.5 μm region. Fe 3+- and H 2O-bearing sulfates all showed changes in the appearance and/or reduction in depths of hydroxo-bridged Fe 3+ absorption bands, particularly at 0.43 μm. The spectral changes were often accompanied by visible color changes, suggesting that subsurface sulfates exposed to the martian surface environment may undergo measurable changes in reflectance spectra and color over short periods of time (days to weeks). Organic-bearing geological materials showed no measurable change in C sbnd H related absorption bands, while carbonates and hydroxides also showed no systematic changes in spectral properties. The addition of ultraviolet irradiation did not seem to affect mineral stability or rate of spectral change, with one exception (hexahydrite). In some cases, spectral changes could be related to the formation of specific new phases. The data also suggest that hydrated minerals detected on Mars to date retain their diagnostic spectral properties that allow their unique identification.

  19. Geochemical signature of land-based activities in Caribbean coral surface samples

    Science.gov (United States)

    Prouty, N.G.; Hughen, K.A.; Carilli, J.

    2008-01-01

    Anthropogenic threats, such as increased sedimentation, agrochemical run-off, coastal development, tourism, and overfishing, are of great concern to the Mesoamerican Caribbean Reef System (MACR). Trace metals in corals can be used to quantify and monitor the impact of these land-based activities. Surface coral samples from the MACR were investigated for trace metal signatures resulting from relative differences in water quality. Samples were analyzed at three spatial scales (colony, reef, and regional) as part of a hierarchical multi-scale survey. A primary goal of the paper is to elucidate the extrapolation of information between fine-scale variation at the colony or reef scale and broad-scale patterns at the regional scale. Of the 18 metals measured, five yielded statistical differences at the colony and/or reef scale, suggesting fine-scale spatial heterogeneity not conducive to regional interpretation. Five metals yielded a statistical difference at the regional scale with an absence of a statistical difference at either the colony or reef scale. These metals are barium (Ba), manganese (Mn), chromium (Cr), copper (Cu), and antimony (Sb). The most robust geochemical indicators of land-based activities are coral Ba and Mn concentrations, which are elevated in samples from the southern region of the Gulf of Honduras relative to those from the Turneffe Islands. These findings are consistent with the occurrence of the most significant watersheds in the MACR from southern Belize to Honduras, which contribute sediment-laden freshwater to the coastal zone primarily as a result of human alteration to the landscape (e.g., deforestation and agricultural practices). Elevated levels of Cu and Sb were found in samples from Honduras and may be linked to industrial shipping activities where copper-antimony additives are commonly used in antifouling paints. Results from this study strongly demonstrate the impact of terrestrial runoff and anthropogenic activities on coastal water

  20. Geochemical Signature of Land-based Activities in Caribbean Coral Surface Samples

    Science.gov (United States)

    Prouty, N. G.; Hughen, K.; Carilli, J.

    2007-12-01

    Anthropogenic threats to the Mesoamerican Caribbean Reef Ecoregion, resulting from increased sedimentation, agrochemical run-off, coastal development, tourism and overfishing, are of great concern for future coral reef health and sustainability. Abundances of trace metal in corals can be used to monitor and identify the impact of land-based activities on the reef itself. In this study we demonstrate that surface coral samples from four sites in the Mesoamerican Caribbean Reef Ecoregion, Turneffe Atoll, Sapodilla Cayes and Honduras Bay Islands (Utila and Cayos Cochinos), yield statistically different chemical signatures due to their water quality and relative distance from pollution sources. Specifically, samples from the Sapodilla Cayes and the Bay Islands of Honduras yield elevated Ba/Ca and Mn/Ca levels, indicative of greater exposure to sediment-laden runoff form the south. In a similar manner, elevated coral Pb/Ca and Zn/Ca, and Sb/Ca and Cu/Ca values can be linked to mining activities and the use of antifouling paints, respectively. In addition, site heterogeneity was investigated by analyzing replicate cores at a single site from different colonies. We show that regional variability within the Sapodilla Cayes Marine Reserve can be explained by relative location and orientation within the reef and distance from the continental shelf. Our results indicate good reproducibility for the majority of trace metals investigated (not including Sr/Ca or Mg/Ca), suggesting that local environmental changes such as seawater chemistry, and not climate, is the dominant influence on the metal/Ca ratios.

  1. A spectral formalism for computing three-dimensional deformations due to surface loads. 1: Theory

    Science.gov (United States)

    Mitrovica, J. X.; Davis, J. L.; Shapiro, I. I.

    1994-01-01

    We outline a complete spectral formalism for computing high spatial resolution three-dimensional deformations arising from the surface mass loading of a spherically symmetric planet. The main advantages of the formalism are that all surface mass loads are always described using a consistent mathematical representation and that calculations of deformation fields for various spatial resolutions can be performed by simpley altering the spherical harmonic degree truncation level of the procedure. The latter may be important when incorporating improved observational constraints on a particular surface mass load, when considering potential errors in the computed field associated with mass loading having a spatial scale unresolved by the observational constraints, or when treating a number of global surface mass loads constrained with different spatial resolutions. The advantages do not extend to traditional 'Green's function' approaches which involve surface element discretizations of the global mass loads. Another advantage of the spectral formalism, over the Green's function approach, is that a posteriori analyses of the computed deformation fields are easily performed. In developing the spectral formalism, we consider specific cases where the Earth's mantle is assumed to respond as an elastic, slightly anelastic, or linear viscoelastic medium. In the case of an elastic or slightly anelastic mantle rheology the spectral response equations incorporate frequency dependent Love numbers. The formalism can therefore be used, for example, to compute the potentially resonant deformational response associated with the free core nutation and Chandler wobble eigenfunctions. For completeness, the spectral response equations include both body forces, as arise from the gravitational attraction of the Sun and the Moon, and surface mass loads. In either case, and for both elastic and anelastic mantle rheologies, we outline a pseudo-spectral technique for computing the ocean

  2. Combining random forest and 2D correlation analysis to identify serum spectral signatures for neuro-oncology.

    Science.gov (United States)

    Smith, Benjamin R; Ashton, Katherine M; Brodbelt, Andrew; Dawson, Timothy; Jenkinson, Michael D; Hunt, Neil T; Palmer, David S; Baker, Matthew J

    2016-06-07

    Fourier transform infrared (FTIR) spectroscopy has long been established as an analytical technique for the measurement of vibrational modes of molecular systems. More recently, FTIR has been used for the analysis of biofluids with the aim of becoming a tool to aid diagnosis. For the clinician, this represents a convenient, fast, non-subjective option for the study of biofluids and the diagnosis of disease states. The patient also benefits from this method, as the procedure for the collection of serum is much less invasive and stressful than traditional biopsy. This is especially true of patients in whom brain cancer is suspected. A brain biopsy is very unpleasant for the patient, potentially dangerous and can occasionally be inconclusive. We therefore present a method for the diagnosis of brain cancer from serum samples using FTIR and machine learning techniques. The scope of the study involved 433 patients from whom were collected 9 spectra each in the range 600-4000 cm(-1). To begin the development of the novel method, various pre-processing steps were investigated and ranked in terms of final accuracy of the diagnosis. Random forest machine learning was utilised as a classifier to separate patients into cancer or non-cancer categories based upon the intensities of wavenumbers present in their spectra. Generalised 2D correlational analysis was then employed to further augment the machine learning, and also to establish spectral features important for the distinction between cancer and non-cancer serum samples. Using these methods, sensitivities of up to 92.8% and specificities of up to 91.5% were possible. Furthermore, ratiometrics were also investigated in order to establish any correlations present in the dataset. We show a rapid, computationally light, accurate, statistically robust methodology for the identification of spectral features present in differing disease states. With current advances in IR technology, such as the development of rapid discrete

  3. Spectral Approximation of an Oldroyd Liquid Draining down a Porous Vertical Surface

    Directory of Open Access Journals (Sweden)

    F. Talay Akyildiz

    2011-01-01

    Full Text Available Consideration is given to the free drainage of an Oldroyd four-constant liquid from a vertical porous surface. The governing systems of quasilinear partial differential equations are solved by the Fourier-Galerkin spectral method. It is shown that Fourier-Galerkin approximations are convergent with spectral accuracy. An efficient and accurate algorithm based on the Fourier-Galerkin approximations for the governing system of quasilinear partial differential equations is developed and implemented. Numerical results indicating the high accuracy and effectiveness of this algorithm are presented. The effect of the material parameters, elasticity, and porous medium constant on the centerline velocity and drainage rate is discussed.

  4. Spectral signatures of dissipative standing shocks and mass outflow in presence of Comptonization around a black hole

    CERN Document Server

    Mondal, Santanu; Debnath, Dipak

    2014-01-01

    Accretion flows having positive specific energy are known to produce outflows and winds which escape to a large distance. According to Two Component Advective Flow (TCAF) model, centrifugal pressure dominated region of the flow just outside the black hole horizon, with or without shocks, acts as the base of this outflow. Electrons from this region are depleted due to the wind and consequently, energy transfer rate due to inverse Comptonization of low energy photons are affected. Specifically, it becomes easier to cool this region and emerging spectrum is softened. Our main goal is to show spectral softening due to mass outflow in presence of Compton cooling. To achieve this, we modify Rankine-Hugoniot relationships at the shock front when post-shock region suffers mass loss due to winds and energy loss due to inverse Comptonization. We solve two-temperature equations governing an accretion flow around a black hole which include Coulomb exchange between protons and electrons and other major radiative processes...

  5. 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.

  6. Spectrally selective surfaces for ground and space-based instrumentation: support for a resource base

    Science.gov (United States)

    McCall, Susan H.; Sinclair, R. Lawrence; Pompea, Stephen M.; Breault, Robert P.

    1993-11-01

    The performance of space telescopes, space instruments, and space radiator systems depends critically upon the selection of appropriate spectrally selective surfaces. Many space programs have suffered severe performance limitations, schedule setbacks, and spent hundreds of thousands of dollars in damage control because of a lack of readily-accessible, accurate data on the properties of spectrally selective surfaces, particularly black surfaces. A Canadian effort is underway to develop a resource base (database and support service) to help alleviate this problem. The assistance of the community is required to make the resource base comprehensive and useful to the end users. The paper aims to describe the objectives of this project. In addition, a request for information and support is made for various aspects of the project. The resource base will be useful for both ground and space-based instrumentation.

  7. A 3-D Non-hydrostatic Numerical Study of Frontal Structures and Their Surface Signatures in Estuaries

    Science.gov (United States)

    Zhou, Z.; Honegger, D.; Hsu, T. J.; Shi, F.; Kirby, J. T., Jr.; Haller, M. C.

    2016-12-01

    The 3D nonhydrostatic surface- and terrain-following coastal model, NHwave, has been used to study shear instabilities and large coherent structures in estuaries during buoyant ebb flows and it was demonstrated that such modeling strategy is effective in providing the relationships between surface signatures and water column processes. In this study, NHwave is further used to help the understanding of the complex flow patterns and turbulent coherent structures during the flood condition in the Mouth of Columbia River (MCR). X-band marine radar imagery indicates strong surface velocity divergence at the MCR, which is associated with a landward-migrating, bottom-hopping saline current according to limited in-situ sensor data. We are able to demonstrate that NHwave can reproduce the strong surface velocity divergence during flood of MCR. The frontal zone of the modeled bottom-hopping density current can induce intense surface velocity divergence, which is of similar structure and magnitude to the observed radar signal. However, the numerical resolution is not sufficient to resolve shear instabilities due to the large domain size in the two horizontal directions in MCR. A detailed high-resolution simulation of a saline density current in an idealized channel with an internal Froude number and Reynolds number similar to the salt water intrusion at MCR is further carried out to understand the role of coherent structures in the frontal zone in determining the surface signatures and turbulent mixing.

  8. X-ray polarimetric signatures induced by spectral variability in the framework of the receding torus model

    Science.gov (United States)

    Marin, F.; Goosmann, R. W.; Petrucci, P.-O.

    2016-06-01

    Context. Obscuring circumnuclear dust is a well-established constituent of active galactic nuclei (AGN). Traditionally referred to as the receding dusty torus, its inner radius and angular extension should depend on the photo-ionizing luminosity of the central source. Aims: We quantify the expected time-dependent near-infrared (NIR), optical, ultraviolet (UV) and X-ray polarization of a receding dusty torus as a function of the variable X-ray flux level and spectral shape. Methods: Using a Monte Carlo approach, we simulate the radiative transfer between the multiple components of an AGN adopting model constraints from the bright Seyfert galaxy NGC 4151. We compare our model results to the observed NIR to UV polarization of the source and predict its X-ray polarization. Results: We find that the 2-8 keV polarization fraction of a standard AGN model varies from less then a few percent along polar viewing angles up to tens of percent at equatorial inclinations. At viewing angles around the type-1/type-2 transition, there is a different X-ray polarization variability in a static or a receding torus scenario. In the former case, the expected 2-8 keV polarization of NGC 4151 is found to be 1.21% ± 0.34% with a constant polarization position angle, while in the latter scenario it varies from 0.1% to 6% depending on the photon index of the primary radiation. Additionally, an orthogonal rotation of the polarization position angle with photon energy appears for very soft primary spectra. Conclusions: Future X-ray polarimetry missions will be able to test whether the receding model is valid for Seyfert galaxies seen at a viewing angle close to the torus horizon. The overall stability of the polarization position angle for photon indexes softer than Γ = 1.5 ensures that reliable measurements of X-ray polarization are possible. We derive a long-term observational strategy for NGC 4151 assuming observations with a small to medium-sized X-ray polarimetry satellite.

  9. Measurement of Wind Signatures on the Sea Surface using an L-band Polarimetric Radiometer

    DEFF Research Database (Denmark)

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

    2002-01-01

    A series of circle flights have been carried out over the wind driven sea, using the EMIRAD L-band polarimetric radiometer, described in J. Rotboll et al. (2001). Data are calibrated and corrected for aircraft attitude, and 360 degrees azimuth profiles are generated. The results show some variation...... over a full circle, typically about 1 K, and no clear, repeated azimuth signature from circle to circle is identified. Averaging reduces the variations, and frequency analysis of the profiles show an almost flat spectrum, which excludes a simple extrapolation of wind signatures, known at higher...

  10. The use of spectral skin reflectivity and laser doppler vibrometry data to determine the optimal site and wavelength to collect human vital sign signatures

    Science.gov (United States)

    Byrd, Kenneth A.; Kaur, Balvinder; Hodgkin, Van A.

    2012-06-01

    The carotid artery has been used extensively by researchers to demonstrate that Laser Doppler Vibrometry (LDV) is capable of exploiting vital sign signatures from cooperative human subjects at stando. Research indicates that, the carotid, although good for cooperative and non-traumatic scenarios, is one of the first vital signs to become absent or irregular when a casualty is hemorrhaging and in progress to circulatory (hypovolemic) shock. In an effort to determine the optimal site and wavelength to measure vital signs off human skin, a human subject data collection was executed whereby 14 subjects had their spectral skin reflectivity and vital signs measured at five collection sites (carotid artery, chest, back, right wrist and left wrist). In this paper, we present our findings on using LDV and re ectivity data to determine the optimal collection site and wavelength that should be used to sense pulse signals from quiet and relatively motionless human subjects at stando. In particular, we correlate maximum levels of re ectivity across the ensemble of 14 subjects with vital sign measurements made with an LDV at two ranges, for two scenarios.

  11. Study of the chemical evolution and spectral signatures of some interstellar precursor molecules of adenine, glycine alanine

    CERN Document Server

    Majumdar, Liton; Chakrabarti, Sandip K; Chakrabarti, Sonali; 10.1016/j.newast.2012.09.002

    2012-01-01

    We carry out a quantum chemical calculation to obtain the infrared and electronic absorption spectra of several complex molecules of the interstellar medium (ISM). These molecules are the precursors of adenine, glycine & alanine. They could be produced in the gas phase as well as in the ice phase. We carried out a hydro-chemical simulation to predict the abundances of these species in the gas as well as in the ice phase. Gas and grains are assumed to be interacting through the accretion of various species from the gas phase on to the grain surface and desorption (thermal evaporation and photo-evaporation) from the grain surface to the gas phase. Depending on the physical properties of the cloud, the calculated abundances varies. The influence of ice on vibrational frequencies of different pre-biotic molecules was obtained using Polarizable Continuum Model (PCM) model with the integral equation formalism variant (IEFPCM) as default SCRF method with a dielectric constant of 78.5. Time dependent density func...

  12. Development of a high spectral resolution surface albedo product for the ARM Southern Great Plains Central Facility

    Energy Technology Data Exchange (ETDEWEB)

    McFarlane, Sally A.; Gaustad, Krista L.; Mlawer, Eli J.; Long, Charles N.; Delamere, Jennifer

    2011-09-01

    We present a method for identifying dominant surface type and estimating high spectral resolution surface albedo at the Atmospheric Radiation Measurement (ARM) facility at the Southern Great Plains (SGP) site in Oklahoma for use in radiative transfer calculations. Given a set of 6-channel narrowband visible and near-infrared irradiance measurements from upward and downward looking multi-filter radiometers (MFRs), four different surface types (snow-covered, green vegetation, partial vegetation, non-vegetated) can be identified. A normalized difference vegetation index (NDVI) is used to distinguish between vegetated and non-vegetated surfaces, and a scaled NDVI index is used to estimate the percentage of green vegetation in partially vegetated surfaces. Based on libraries of spectral albedo measurements, a piecewise continuous function is developed to estimate the high spectral resolution surface albedo for each surface type given the MFR albedo values as input. For partially vegetated surfaces, the albedo is estimated as a linear combination of the green vegetation and non-vegetated surface albedo values. The estimated albedo values are evaluated through comparison to high spectral resolution albedo measurements taken during several Intensive Observational Periods (IOPs) and through comparison of the integrated spectral albedo values to observed broadband albedo measurements. The estimated spectral albedo values agree well with observations for the visible wavelengths constrained by the MFR measurements, but have larger biases and variability at longer wavelengths. Additional MFR channels at 1100 nm and/or 1600 nm would help constrain the high resolution spectral albedo in the near infrared region.

  13. Spatially Complete Global Spectral Surface Albedos: Value-Added Datasets Derived from Terra MODIS Land Products

    Science.gov (United States)

    Moody, Eric G.; King, Michael D.; Platnick, Steven; Schaaf, Crystal B.; Gao, Feng

    2004-01-01

    Land surface albedo is an important parameter in describing the radiative properties of the earth s surface as it represents the amount of incoming solar radiation that is reflected from the surface. The amount and type of vegetation of the surface dramatically alters the amount of radiation that is reflected; for example, croplands that contain leafy vegetation will reflect radiation very differently than blacktop associated with urban areas. In addition, since vegetation goes through a growth, or phenological, cycle, the amount of radiation that is reflected changes over the course of a year. As a result, albedo is both temporally and spatially dependant upon global location as there is a distribution of vegetated surface types and growing conditions. Land surface albedo is critical for a wide variety of earth system research projects including but not restricted to remote sensing of atmospheric aerosol and cloud properties from space, ground-based analysis of aerosol optical properties from surface-based sun/sky radiometers, biophysically-based land surface modeling of the exchange of energy, water, momentum, and carbon for various land use categories, and surface energy balance studies. These projects require proper representation of the surface albedo s spatial, spectral, and temporal variations, however, these representations are often lacking in datasets prior to the latest generation of land surface albedo products.

  14. On-line surface inspection using cylindrical lens-based spectral domain low-coherence interferometry.

    Science.gov (United States)

    Tang, Dawei; Gao, Feng; Jiang, X

    2014-08-20

    We present a spectral domain low-coherence interferometry (SD-LCI) method that is effective for applications in on-line surface inspection because it can obtain a surface profile in a single shot. It has an advantage over existing spectral interferometry techniques by using cylindrical lenses as the objective lenses in a Michelson interferometric configuration to enable the measurement of long profiles. Combined with a modern high-speed CCD camera, general-purpose graphics processing unit, and multicore processors computing technology, fast measurement can be achieved. By translating the tested sample during the measurement procedure, real-time surface inspection was implemented, which is proved by the large-scale 3D surface measurement in this paper. ZEMAX software is used to simulate the SD-LCI system and analyze the alignment errors. Two step height surfaces were measured, and the captured interferograms were analyzed using a fast Fourier transform algorithm. Both 2D profile results and 3D surface maps closely align with the calibrated specifications given by the manufacturer.

  15. Spectral analysis of quasi-stationary sea surface topography from GRACE mission

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zizhan; LU Yang

    2005-01-01

    During the last two decades satellite altimetry has offered an abundance of measurements of the sea surface resulting in the improvement of global mean sea surface height (MSSH) and marine geoid determination. On the other hand, with the launching of new generation gravity satellites, some high accuracy long-wavelength gravity models are available. These breakthroughs give us a great opportunity for new estimation of quasi-stationary sea surface topography (QSST). In this paper, the new gravity model GGM01C derived from GRACE mission is briefly presented, and a new global high precision and high-resolution QSST is determined based on the GGM01C model and the global MSSH. The spectral features of the QSST estimated by GGM01C and EGM96 gravity model to degree/order 200 are discussed by spectral analysis. As a result, the QSST is mainly composed of long waves, medium waves partially and short waves scarcely, its power spectral structures are different between the zonal direction and the meridional direction, there are great differences between the two models, which maybe explain why the ocean currents derived from the two gravity models by Tapley show different patterns.

  16. Effect of spectrally varying albedo of vegetation surfaces on shortwave radiation fluxes and direct aerosol forcing

    Directory of Open Access Journals (Sweden)

    L. Zhu

    2012-06-01

    Full Text Available This study develops an algorithm for the representation of large spectral variations of albedo over vegetation surfaces based on Moderate Resolution Imaging Spectrometer (MODIS observations at 7 discrete channels centered at 0.47, 0.55, 0.67, 0.86, 1.24, 1.63, and 2.11 μm. The MODIS 7-channel observations miss several major features of vegetation albedo including the vegetation red edge near 0.7 μm and vegetation absorption features at 1.48 and 1.92 μm. We characterize these features by investigating aerosol forcing in different spectral ranges. We show that the correction at 0.7 μm is the most sensitive and important due to the presence of the red edge and strong solar radiation; the other two corrections are less sensitive due to the weaker solar radiation and strong atmospheric water absorption. Four traditional approaches for estimating the reflectance spectrum and the MODIS enhanced vegetation albedo (MEVA are tested against various vegetation types: dry grass, green grass, conifer, and deciduous from the John Hopkins University (JHU spectral library; aspens from the US Geological Survey (USGS digital spectral library; and Amazon vegetation types. Compared to traditional approaches, MEVA improves the accuracy of the outgoing flux at the top of the atmosphere by over 60 W m−2 and aerosol forcing by over 10 W m−2. Specifically, for Amazon vegetation types, MEVA can improve the accuracy of daily averaged aerosol forcing at equator at equinox by 3.7 W m−2 (about 70% of the aerosol forcing calculated with high spectral resolution surface reflectance. These improvements indicate that MEVA can contribute to vegetation covered regional climate studies, and help to improve understanding of climate processes and climate change.

  17. Mars surface weathering products and spectral analogs: Palagonites and synthetic iron minerals

    Science.gov (United States)

    Golden, D. C.; Ming, D. W.; Morris, R. V.; Lauer, H. V., Jr.

    1992-01-01

    There are several hypotheses regarding the formation of Martian surface fines. These surface fines are thought to be products of weathering processes occurring on Mars. Four major weathering environments of igneous rocks on Mars have been proposed; (1) impact induced hydrothermal alterations; (2) subpermafrost igneous intrusion; (3) solid-gas surface reactions; and (4) subaerial igneous intrusion over permafrost. Although one or more of these processes may be important on the Martian surface, one factor in common for all these processes is the reaction of solid or molten basalt with water (solid, liquid, or gas). These proposed processes, with the exception of solid-gas surface reactions, are transient processes. The most likely product of transient hydrothermal processes are layer silicates, zeolites, hydrous iron oxides and palagonites. The long-term instability of hydrous clay minerals under present Martian conditions has been predicted; however, the persistence of such minerals due to slow kinetics of dehydration, or entrapment in permafrost, where the activity of water is high, can not be excluded. Anhydrous oxides of iron (e.g., hematite and maghemite) are thought to be stable under present Martian surface conditions. Oxidative weathering of sulfide minerals associated with Martian basalts has been proposed. Weathering of sulfide minerals leads to a potentially acidic permafrost and the formation of Fe(3) oxides and sulfates. Weathering of basalts under acidic conditions may lead to the formation of kaolinite through metastable halloysite and metahalloysite. Kaolinite, if present, is thought to be a thermodynamically stable phase at the Martian surface. Fine materials on Mars are important in that they influence the surface spectral properties; these fines are globally distributed on Mars by the dust storms and this fraction will have the highest surface area which should act as a sink for most of the absorbed volatiles near the surface of Mars. Therefore

  18. Modelling the passive microwave signature from land surfaces: a review of recent results and application to the SMOS & SMAP soil moisture retrieval algorithms

    Science.gov (United States)

    Two passive microwave missions are currently operating at L-band to monitor surface soil moisture (SM) over continental surfaces. The SMOS sensor, based on an innovative interferometric technology enabling multi-angular signatures of surfaces to be measured, was launched in November 2009....

  19. Spectral simulation of thermocapillary convection with a deformable free surface using boundary-fitted coordinates

    Science.gov (United States)

    Ahmed, Ikramuddin

    A Chebyshev-spectral collocation scheme has been developed to simulate thermocapillary convection processes in a differentially heated cavity with and without buoyancy effects. The time-dependent Navier- Stokes equations in primitive variables were solved with a semi-implicit scheme using the influence matrix technique. The deformable free surface was incorporated by means of a boundary-fitted coordinate (BFC) system. The BFC grid was generated by solving a system of elliptic equations. An iterative scheme based on finite difference methods was found to be sufficient for calculating a smooth distribution of grid-points for relatively low degrees of deformation of the free surface. The metrics of transformation, however, were calculated spectrally in order to achieve a high order of accuracy in the a posteriori mapping of the physical grid to the computational grid. The overall scheme was found to be efficient, economical, and capable of resolving the complex hydrodynamic and thermal structures in thermocapillarity driven flows with deformable free surfaces. The scheme was also modified to study problems with very high Marangoni numbers and non-deformable free surfaces, and later extended to three dimensions with periodic boundary conditions in order to explore the transitions to fully three dimensional phenomena that are anticipated in industrially relevant flow configurations.

  20. Spectral properties of Titan's impact craters imply chemical weathering of its surface

    Science.gov (United States)

    Barnes, J. W.; Sotin, C.; MacKenzie, S.; Soderblom, J. M.; Le Mouélic, S.; Kirk, R. L.; Stiles, B. W.; Malaska, M. J.; Le Gall, A.; Brown, R. H.; Baines, K. H.; Buratti, B.; Clark, R. N.; Nicholson, P. D.

    2015-01-01

    Abstract We examined the spectral properties of a selection of Titan's impact craters that represent a range of degradation states. The most degraded craters have rims and ejecta blankets with spectral characteristics that suggest that they are more enriched in water ice than the rims and ejecta blankets of the freshest craters on Titan. The progression is consistent with the chemical weathering of Titan's surface. We propose an evolutionary sequence such that Titan's craters expose an intimate mixture of water ice and organic materials, and chemical weathering by methane rainfall removes the soluble organic materials, leaving the insoluble organics and water ice behind. These observations support the idea that fluvial processes are active in Titan's equatorial regions. PMID:27656006

  1. Spectral Properties of ENVISAT ASAR and QuikSCAT Surface Winds in the North Sea

    DEFF Research Database (Denmark)

    Karagali, Ioanna; Larsén, Xiaoli Guo; Badger, Merete

    2013-01-01

    Spectra derived from ENVISAT Advanced Synthetic Aperture Radar (ASAR) and QuikSCAT near-surface ocean winds are investigated over the North Sea. The two sensors offer a wide range of spatial resolutions, from 600 m to 25 km, with different spatial coverage over the area of interest. This provides...... a unique opportunity to study the impact of the spatial resolution on the spectral properties of the wind over a wide range of length scales. Initially, a sub-domain in the North Sea is chosen, due to the overlap of 87 wind scenes from both sensors. The impact of the spatial resolution is manifested...... or lower. The lower power levels of coarser resolution wind products, particularly when comparing QuikSCAT to ENVISAT ASAR, strongly suggest that the effective resolution of the wind products should be high enough to resolve the spectral properties. Spectra computed from 87 wind maps are consistent...

  2. Group interpretation of the spectral parameter. The case of isothermic surfaces

    Science.gov (United States)

    Cieśliński, Jan L.; Kobus, Artur

    2017-03-01

    It is well known that in some cases the spectral parameter has a group interpretation. We discuss in detail the case of Gauss-Codazzi equations for isothermic surfaces immersed in E3. The algebra of Lie point symmetries is 4-dimensional and all these symmetries are also symmetries of the Gauss-Weingarten equations (which can be considered as so(3) -valued non-parametric linear problem). In order to obtain a non-removable spectral parameter one has to consider so(4 , 1) -valued linear problem which has a 3-dimensional algebra of Lie point symmetries. The missing symmetry introduces a non-removable parameter. In the second part of the paper we extend these results on the case of isothermic immersions in arbitrary multidimensional Euclidean spaces. In order to simplify calculations the problem was formulated in terms of a Clifford algebra.

  3. Effect of emissivity uncertainty on surface temperature retrieval over urban areas: Investigations based on spectral libraries

    Science.gov (United States)

    Chen, Feng; Yang, Song; Su, Z.; Wang, Kai

    2016-04-01

    Land surface emissivity (LSE) is a prerequisite for retrieving land surface temperature (LST) through single channel methods. According to error model, a 0.01 (1%) uncertainty of LSE may result in a 0.5 K error in LST under a moderate condition, while an obvious error (approximately 1 K) is possible under a warmer and less humid situation. Significant emissivity variations are presented among the anthropogenic materials in three spectral libraries, which raise a critical question that whether urban LSE can be estimated accurately to meet the needs for LST retrieval. Methods widely used for urban LSE estimation are investigated, including the classification-based method, the spectral-index based method, and the linear spectral mixture model (LSMM). Results indicate that the classification-based method may not be effectively applicable for urban LSE estimation, due mainly to the insignificant relation between the short-wave multispectral reflectance and the long-wave thermal emissivity shown by the spectra. Compared with the classification-based method, the LSMM shows relatively more accurate predictions, whereas, the performance of the LSMM largely depends on the determination of endmembers. Obvious uncertainties in LSE estimation likely appear if endmembers are determined improperly. Increasing the spectra for endmembers is a practical and beneficial means for LSMM when there is not a priori knowledge, which emphasizes the necessity of building a comprehensive spectral library of urban materials. Furthermore, the LST retrieval from a single channel of Landsat 8 is more challenging as compared with the retrieval from the channels of its predecessors-Landsat 4/5/7.

  4. Surface Compositional Units on Mercury from Spectral Reflectance at Ultraviolet to Near-infrared Wavelengths

    Science.gov (United States)

    Izenberg, N. R.; Holsclaw, G. M.; Domingue, D. L.; McClintock, W. E.; Klima, R. L.; Blewett, D. T.; Helbert, J.; Head, J. W.; Sprague, A. L.; Vilas, F.; Solomon, S. C.

    2012-12-01

    The Mercury Atmospheric and Surface Composition Spectrometer (MASCS) on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft has been acquiring reflectance spectra of Mercury's surface for over 16 months. The Visible and Infrared Spectrograph (VIRS) component of MASCS has accumulated a global data set of more than 2 million spectra over the wavelength range 300-1450 nm. We have derived a set of VIRS spectral units (VSUs) from the following spectral parameters: visible brightness (R575: reflectance at 575 nm); visible/near-infrared reflectance ratio (VISr: reflectance at 415 nm to that at 750 nm); and ultraviolet reflectance ratio (UVr: reflectance at 310 nm to that at 390 nm). Five broad, slightly overlapping VSUs may be distinguished from these parameters. "Average VSU" areas have spectral parameters close to mean global values. "Dark blue VSU" areas have spectra with low R575 and high UVr. "Red VSU" areas have spectra with low UVr and higher VISr and R575 than average. "Intermediate VSU" areas have spectra with higher VISr than VSU red, generally higher R575, and a wide range of UVr. "Bright VSU" areas have high R575 and VISr and intermediate UVr. Several units defined by morphological or multispectral criteria correspond to specific VSUs, including low-reflectance material (dark blue VSU), pyroclastic deposits (red VSU), and hollows (intermediate VSU), but these VSUs generally include other types of areas as well. VSU definitions are complementary to those obtained by unsupervised clustering analysis. The global distribution of VIRS spectral units provides new information on Mercury's geological evolution. Much of Mercury's northern volcanic plains show spectral properties ranging from those of average VSU to those of red VSU, as does a large region in the southern hemisphere centered near 50°S, 245°E. Dark blue VSU material is widely distributed, with concentrations south of the northern plains, around the Rembrandt and

  5. Thermal, spectral, and surface properties of LED light-polymerized bulk fill resin composites.

    Science.gov (United States)

    Pişkin, Mehmet Burçin; Atalı, Pınar Yılmaz; Figen, Aysel Kantürk

    2015-02-01

    The aim of this study was to evaluate the thermal, spectral, and surface properties of four different bulk fill materials – SureFil SDR (SDR, Dentsplay DETREY), QuixFil (QF, Dentsplay DETREY), X-tra base (XB, Voco) X-tra fil (XF, Voco) – polymerized by light-emitting diode (LED). Resin matrix, filler type, size and amount, and photoinitiator types influence the degree of conversion. LED-cured bulk fill composites achieved sufficient polymerization. Scanning electron microscope (SEM) analysis revealed different patterns of surface roughness, depending on the composite material. Bulk fill materials showed surface characteristics similar to those of nanohybrid composites. Based on the thermal analysis results, glass transition (T(g)) and initial degradation (T(i)) temperatures changed depending on the bulk fill resin composites.

  6. Quantitative roughness characterization of geological surfaces and implications for radar signature analysis

    DEFF Research Database (Denmark)

    Dierking, Wolfgang

    1999-01-01

    Stochastic surface models are useful for analyzing in situ roughness profiles and synthetic aperture radar (SAR) images of geological terrain. In this paper, two different surface models are discussed: surfaces with a stationary random roughness (conventional model) and surfaces with a power...

  7. 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

    Current pig house cleaning procedures are hazardous to the health of farm workers, and yet necessary if the spread of disease between batches of animals is to be satisfactorily controlled. Autonomous cleaning using robot technology offers salient benefits. This report addresses the feasibility...... 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...

  8. Nonlocal Symmetries, Spectral Parameter and Minimal Surfaces in AdS/CFT

    CERN Document Server

    Klose, Thomas; Münkler, Hagen

    2016-01-01

    We give a general account of nonlocal symmetries in symmetric space models and their relation to the AdS/CFT correspondence. In particular, we study a master symmetry which generates the spectral parameter and acts as a level-raising operator on the classical Yangian generators. The master symmetry extends to an infinite tower of symmetries with nonlocal Casimir elements as associated conserved charges. We discuss the algebraic properties of these symmetries and establish their role in explaining the recently observed one-parameter deformation of holographic Wilson loops. Finally, we provide a numerical framework, in which discretized minimal surfaces and their master symmetry deformation can be calculated.

  9. Characterizing Earthflow Surface Morphology With Statistical and Spectral Analyses of Airborne Laser Altimetry

    Science.gov (United States)

    McKean, J.; Roering, J.

    High-resolution laser altimetry can depict the topography of large landslides with un- precedented accuracy and allow better management of the hazards posed by such slides. The surface of most landslides is rougher, on a local scale of a few meters, than adjacent unfailed slopes. This characteristic can be exploited to automatically detect and map landslides in landscapes represented by high resolution DTMs. We have used laser altimetry measurements of local topographic roughness to identify and map the perimeter and internal features of a large earthflow in the South Island, New Zealand. Surface roughness was first quantified by statistically characterizing the local variabil- ity of ground surface orientations using both circular and spherical statistics. These measures included the circular resultant, standard deviation and dispersion, and the three-dimensional spherical resultant and ratios of the normalized eigenvalues of the direction cosines. The circular measures evaluate the amount of change in topographic aspect from pixel-to-pixel in the gridded data matrix. The spherical statistics assess both the aspect and steepness of each pixel. The standard deviation of the third di- rection cosine was also used alone to define the variability in just the steepness of each pixel. All of the statistical measures detect and clearly map the earthflow. Cir- cular statistics also emphasize small folds transverse to the movement in the most active zone of the slide. The spherical measures are more sensitive to the larger scale roughness in a portion of the slide that includes large intact limestone blocks. Power spectra of surface roughness were also calculated from two-dimensional Fourier transformations in local test areas. A small earthflow had a broad spectral peak at wavelengths between 10 and 30 meters. Shallower soil failures and surface erosion produced surfaces with a very sharp spectral peak at 12 meters wavelength. Unfailed slopes had an order of magnitude

  10. Applying Spectral Unmixing to Determine Surface Water Parameters in a Mining Environment

    Directory of Open Access Journals (Sweden)

    Veronika Kopačková

    2014-11-01

    Full Text Available Compared to natural waters, mine waters represent an extreme water type that is frequently heavily polluted. Although they have been traditionally monitored by in situ measurements of point samples taken at regular intervals, the emergence of a new generation of multispectral and hyperspectral (HS sensors means that image spectroscopy has the potential to become a modern method for monitoring polluted surface waters. This paper describes an approach employing linear Spectral Unmixing (LSU for analysis of hyperspectral image data to map the relative abundances of mine water components (dissolved Fe—Fediss, dissolved organic carbon—DOC, undissolved particles. The ground truth data (8 monitored ponds were used to validate the results of spectral mapping. The same approach applied to HS data was tested using the image data resampled to WorldView2 (WV2 spectral resolution. A key aspect of the image data processing was to define the proper pure image end members for the fundamental water types. The highest correlations detected between the studied water parameters and the fractional images using the HyMap and the resampled WV2 data, respectively, were: dissolved Fe (R2 = 0.74 and R2vw2 = 0.6, undissolved particles (R2 = 0.57 and R2vw2 = 0.49 and DOC (R2 = 0.42 and R2vw2 < 0.40. These fractional images were further classified to create semi-quantitative maps. In conclusion, the classification still benefited from the higher spectral resolution of the HyMap data; however the WV2 reflectance data can be suitable for mapping specific inherent optical properties (SIOPs, which significantly differ from one another from an optical point of view (e.g., mineral suspension, dissolved Fe and phytoplankton, but it seems difficult to differentiate among diverse suspension particles, especially when the waters have more complex properties (e.g., mineral particles, DOC together with tripton or other particles, etc..

  11. Directionality and maneuvering effects on a surface ship underwater acoustic signature.

    Science.gov (United States)

    Trevorrow, Mark V; Vasiliev, Boris; Vagle, Svein

    2008-08-01

    This work examines underwater source spectra of a small (560 tons, 40 m length), single-screw oceanographic vessel, focusing on directionality and effects of maneuvers. The measurements utilized a set of four, self-contained buoys with GPS positioning, each recording two calibrated hydrophones with effective acoustic bandwidth from 150 Hz to 5 kHz. In straight, constant-speed runs at speeds up to 6.2 m s(-1), the ship source spectra showed spectral levels in reasonable agreement with reference spectra. The broadband source level was observed to increase as approximately speed to the fourth power over the range of 2.6-6.1 m s(-1), partially biased at low speeds by nonpropulsion machinery signals. Source directionality patterns were extracted from variations in source spectra while the ship transited past the buoy field. The observed spectral source levels exhibited a broadside maximum, with bow and stern aspect reduced by approximately 12-9 dB, respectively, independent of frequency. An empirical model is proposed assuming that spectral source levels exhibit simultaneous variations in aspect angle, speed, and turn rate. After correction for source directionality and speed during turning maneuvers, an excess of up to 18 dB in one-third octave source levels was observed.

  12. Impact of soil moisture and winter wheat height from the Loess Plateau in Northwest China on surface spectral albedo

    Science.gov (United States)

    Li, Zhenchao; Yang, Jiaxi; Gao, Xiaoqing; Zheng, Zhiyuan; Yu, Ye; Hou, Xuhong; Wei, Zhigang

    2016-12-01

    The understanding of surface spectral radiation and reflected radiation characteristics of different surfaces in different climate zones aids in the interpretation of regional surface energy transfers and the development of land surface models. This study analysed surface spectral radiation variations and corresponding surface albedo characteristics at different wavelengths as well as the relationship between 5-cm soil moisture and surface albedo on typical sunny days during the winter wheat growth period. The analysis was conducted using observational Loess Plateau winter wheat data from 2015. The results show that the ratio of atmospheric downward radiation to global radiation on typical sunny days is highest for near-infrared wavelengths, followed by visible wavelengths and ultraviolet wavelengths, with values of 57.3, 38.7 and 4.0%, respectively. The ratio of reflected spectral radiation to global radiation varies based on land surface type. The visible radiation reflected by vegetated surfaces is far less than that reflected by bare ground, with surface albedos of 0.045 and 0.27, respectively. Thus, vegetated surfaces absorb more visible radiation than bare ground. The atmospheric downward spectral radiation to global radiation diurnal variation ratios vary for near-infrared wavelengths versus visible and ultraviolet wavelengths on typical sunny days. The near-infrared wavelengths ratio is higher in the morning and evening and lower at noon. The visible and ultraviolet wavelengths ratios are lower in the morning and evening and higher at noon. Visible and ultraviolet wavelength surface albedo is affected by 5-cm soil moisture, demonstrating a significant negative correlation. Excluding near-infrared wavelengths, correlations between surface albedo and 5-cm soil moisture pass the 99% confidence test at each wavelength. The correlation with 5-cm soil moisture is more significant at shorter wavelengths. However, this study obtained surface spectral radiation

  13. Development of a high spectral resolution surface albedo product for the ARM Southern Great Plains central facility

    Directory of Open Access Journals (Sweden)

    J. Delamere

    2011-09-01

    Full Text Available We present a method for identifying dominant surface type and estimating high spectral resolution surface albedo at the Atmospheric Radiation Measurement (ARM facility at the Southern Great Plains (SGP site in Oklahoma for use in radiative transfer calculations. Given a set of 6-channel narrowband visible and near-infrared irradiance measurements from upward and downward looking multi-filter radiometers (MFRs, four different surface types (snow-covered, green vegetation, partial vegetation, non-vegetated can be identified. A normalized difference vegetation index (NDVI is used to distinguish between vegetated and non-vegetated surfaces, and a scaled NDVI index is used to estimate the percentage of green vegetation in partially vegetated surfaces. Based on libraries of spectral albedo measurements, a piecewise continuous function is developed to estimate the high spectral resolution surface albedo for each surface type given the MFR albedo values as input. For partially vegetated surfaces, the albedo is estimated as a linear combination of the green vegetation and non-vegetated surface albedo values. The estimated albedo values are evaluated through comparison to high spectral resolution albedo measurements taken during several Intensive Observational Periods (IOPs and through comparison of the integrated spectral albedo values to observed broadband albedo measurements. The estimated spectral albedo values agree well with observations for the visible wavelengths constrained by the MFR measurements, but have larger biases and variability at longer wavelengths. Additional MFR channels at 1100 nm and/or 1600 nm would help constrain the high resolution spectral albedo in the near infrared region.

  14. The surface brightness of dark matter unique signatures of neutralino annihilation in the Galactic halo

    CERN Document Server

    Calcaneo-Roldan, C; Calcaneo-Roldan, Carlos; Moore, Ben

    2000-01-01

    We use high resolution numerical simulations of the formation of cold dark matter halos to simulate the background of decay products from neutralino annihilation, such as gamma-rays or neutrinos. Halos are non-spherical, have steep singular density profiles and contain many thousands of surviving dark matter substructure clumps. This leads to several unique signatures in the gamma-ray background that may be confirmed or rejected by the next generation of gamma-ray experiments. Most importantly, the diffuse background is enhanced by over two orders of magnitude due to annihilation within substructure halos. The largest dark substructures are easily visibly above the background and may account for the unidentified EGRET sources. A deep strip survey of the gamma-ray background would allow the shape of the Galactic halo to be quantified.

  15. Spectral locking in an extended area two-dimensional coherent grating surface emitting laser array

    Energy Technology Data Exchange (ETDEWEB)

    DeFreez, R.K.; Ximen, H.; Bossert, D.J.; Hunt, J.M.; Wilson, G.A.; Elliott, R.A.; Orloff, J. (Dept. of Applied Physics and Electrical Engineering, Oregon Graduate Center, Beaverton, OR (US)); Evans, G.A.; Carlson, N.W.; Lurie, M. (David Sarnoff Research Center, Princeton, NJ (US))

    1990-01-01

    The spectral properties of a monolithic pair of two-dimensional coherent grating surface emitting laser arrays optically coupled by means of total-internal-reflection (TIR) corner turning mirrors have been studied. Each of the pair consists of six groups of ten laterally {ital Y}-coupled, index-guided ridge lasers interspersed with second-order DBR grating sections in the longitudinal direction to provide feedback and surface emitting output coupling. The turning mirrors were formed by focused-ion-beam micromachining channels in the wafer angled at 45{degrees} to the laser waveguide. Locking of the emission spectra of the pair of GSE arrays and shifting of the spectrum of one of the pair by varying the drive current to one gain section in the other is demonstrated.

  16. Transport signatures of surface potentials on three-dimensional topological insulators

    Science.gov (United States)

    Roy, Sthitadhi; Das, Sourin

    2016-02-01

    The spin-momentum-locked nature of the robust surface states of three-dimensional topological insulators (3D TIs) makes them promising candidates for spintronics applications. Surface potentials which respect time-reversal symmetry can exist at the surface between a 3D TI and the trivial vacuum. These potentials can distort the spin texture of the surface states while retaining their gapless nature. In this work, the effect of all such surface potentials on the spin textures is studied. Since a tunnel magnetoresistance signal carries the information of the spin texture, it is proposed that spin-polarized tunneling of electrons to a 3D TI surface can be used to uniquely identify the surface potentials and quantitatively characterize them.

  17. Detection of organic residues on food processing equipment surfaces by spectral imaging method

    Science.gov (United States)

    Qin, Jianwei; Jun, Won; Kim, Moon S.; Chao, Kaunglin

    2010-04-01

    Organic residues on equipment surfaces in poultry processing plants can generate cross contamination and increase the risk of unsafe food for consumers. This research was aimed to investigate the potential of LED-induced fluorescence imaging technique for rapid inspection of organic residues on poultry processing equipment surfaces. High-power blue LEDs with a spectral output at 410 nm were used as the excitation source for a line-scanning hyperspectral imaging system. Common chicken residue samples including fat, blood, and feces from ceca, colon, duodenum, and small intestine were prepared on stainless steel sheets. Fluorescence emission images were acquired from 120 samples (20 for each type of residue) in the wavelength range of 500-700 nm. LED-induced fluorescence characteristics of the tested samples were determined. PCA (principal component analysis) was performed to analyze fluorescence spectral data. Two SIMCA (soft independent modeling of class analogy) models were developed to differentiate organic residues and stainless steel samples. Classification accuracies using 2-class ('stainless steel' and 'organic residue') and 4-class ('stainless steel', 'fat', 'blood', and 'feces') SIMCA models were 100% and 97.5%, respectively. An optimal single-band and a band-pair that are promising for rapid residue detection were identified by correlation analysis. The single-band approach using the selected wavelength of 666 nm could generate false negative errors for chicken blood inspection. Two-band ratio images using 503 and 666 nm (F503/F666) have great potential for detecting various chicken residues on stainless steel surfaces. This wavelength pair can be adopted for developing a LED-based hand-held fluorescence imaging device for inspecting poultry processing equipment surfaces.

  18. Measuring and modeling the effect of surface moisture on the spectral reflectance of coastal beach sand.

    Science.gov (United States)

    Nolet, Corjan; Poortinga, Ate; Roosjen, Peter; Bartholomeus, Harm; Ruessink, Gerben

    2014-01-01

    Surface moisture is an important supply limiting factor for aeolian sand transport, which is the primary driver of coastal dune development. As such, it is critical to account for the control of surface moisture on available sand for dune building. Optical remote sensing has the potential to measure surface moisture at a high spatio-temporal resolution. It is based on the principle that wet sand appears darker than dry sand: it is less reflective. The goals of this study are (1) to measure and model reflectance under controlled laboratory conditions as function of wavelength (λ) and surface moisture (θ) over the optical domain of 350-2500 nm, and (2) to explore the implications of our laboratory findings for accurately mapping the distribution of surface moisture under natural conditions. A laboratory spectroscopy experiment was conducted to measure spectral reflectance (1 nm interval) under different surface moisture conditions using beach sand. A non-linear increase of reflectance upon drying was observed over the full range of wavelengths. Two models were developed and tested. The first model is grounded in optics and describes the proportional contribution of scattering and absorption of light by pore water in an unsaturated sand matrix. The second model is grounded in soil physics and links the hydraulic behaviour of pore water in an unsaturated sand matrix to its optical properties. The optical model performed well for volumetric moisture content θ 0.97), but underestimated reflectance for θ between 24-30% (R2 > 0.92), most notable around the 1940 nm water absorption peak. The soil-physical model performed very well (R2 > 0.99) but is limited to 4% > θ < 24%. Results from a field experiment show that a short-wave infrared terrestrial laser scanner (λ = 1550 nm) can accurately relate surface moisture to reflectance (standard error 2.6%), demonstrating its potential to derive spatially extensive surface moisture maps of a natural coastal beach.

  19. Measuring and modeling the effect of surface moisture on the spectral reflectance of coastal beach sand.

    Directory of Open Access Journals (Sweden)

    Corjan Nolet

    Full Text Available Surface moisture is an important supply limiting factor for aeolian sand transport, which is the primary driver of coastal dune development. As such, it is critical to account for the control of surface moisture on available sand for dune building. Optical remote sensing has the potential to measure surface moisture at a high spatio-temporal resolution. It is based on the principle that wet sand appears darker than dry sand: it is less reflective. The goals of this study are (1 to measure and model reflectance under controlled laboratory conditions as function of wavelength (λ and surface moisture (θ over the optical domain of 350-2500 nm, and (2 to explore the implications of our laboratory findings for accurately mapping the distribution of surface moisture under natural conditions. A laboratory spectroscopy experiment was conducted to measure spectral reflectance (1 nm interval under different surface moisture conditions using beach sand. A non-linear increase of reflectance upon drying was observed over the full range of wavelengths. Two models were developed and tested. The first model is grounded in optics and describes the proportional contribution of scattering and absorption of light by pore water in an unsaturated sand matrix. The second model is grounded in soil physics and links the hydraulic behaviour of pore water in an unsaturated sand matrix to its optical properties. The optical model performed well for volumetric moisture content θ 0.97, but underestimated reflectance for θ between 24-30% (R2 > 0.92, most notable around the 1940 nm water absorption peak. The soil-physical model performed very well (R2 > 0.99 but is limited to 4% > θ < 24%. Results from a field experiment show that a short-wave infrared terrestrial laser scanner (λ = 1550 nm can accurately relate surface moisture to reflectance (standard error 2.6%, demonstrating its potential to derive spatially extensive surface moisture maps of a natural coastal beach.

  20. Surface area dependence of calcium isotopic reequilibration in carbonates: Implications for isotopic signatures in the weathering zone

    Science.gov (United States)

    Fernandez, N. M.; Druhan, J. L.; Potrel, A.; Jacobson, A. D.

    2016-12-01

    The concept of dynamic equilibrium carries the implicit assumption of continued isotopic exchange between a mineral and the surrounding fluid. While this effect has received much attention in the marine paleoproxy literature, it has been relatively overlooked in application to the terrestrial environment. In weathering systems, a potential consequence is that rapid reequilibration may alter or erase isotopic signatures generated during secondary mineral formation. The extent and timescale over which isotopic signatures are reset in these hydrologic systems is unknown. Using reactive transport modeling, we show isotopic reequilibration under conditions reflecting terrestrial hydrologic settings to be significant and dependent on the reactive surface area of the solid. In particular, we suggest that the non-traditional stable isotopes commonly used in application to carbonates (e.g., Ca, Mg, Sr) are sensitive to these effects due to their rapid reaction rates. We aim to characterize the dependence of Ca isotopic reequilibration on surface area during calcite precipitation via batch experiments conducted at ambient temperature over 48-hour time periods. Calcite precipitation was performed in a closed batch reactor utilizing a controlled free-drift method. The batch reactors contained mixed supersaturated solutions of CaCl2 and NaHCO3 at an initial pH of 8.54. Precipitation was initiated by seed inoculation of calcite crystals with two distinct, pre-constrained surface areas. All experiments achieved the same final state of chemical equilibrium, but as expected, the fastest approach to equilibrium occurred for experiments employing calcite seeds with the highest surface area. This implies that differences in equilibrated Ca isotope ratios (δ44/40Ca) should reflect differences in surface area. This prediction is upheld by models of the experiments, indicating a measureable difference in δ44Ca during calcite precipitation where the higher surface area corresponds to

  1. Spectral calibration for deriving surface mineralogy of Asteroid (25143) Itokawa from Hayabusa Near-Infrared Spectrometer (NIRS) Data

    CERN Document Server

    Bhatt, Megha; Corre, Lucille Le; Sanchez, Juan A; Dunn, Tasha; Izawa, Matthew R M; Li, Jian-Yang; Becker, Kris J; Weller, Lynn

    2015-01-01

    We present spectral calibration equations for determining mafic silicate composition of near-Earth asteroid (25143) Itokawa from visible/near-infrared spectra measured using the Near Infrared Spectrometer (NIRS), on board the Japanese Hayabusa spacecraft. Itokawa was the target of the Hayabusa sample return mission and has a surface composition similar to LL-type ordinary chondrites. Existing laboratory spectral calibrations use a spectral wavelength range that is wider (0.75-2.5 microns) than that of the NIRS instrument (0.85-2.1 microns) making them unfit for interpreting the Hayabusa spectral data currently archived in the Planetary Data System. We used laboratory measured near-infrared reflectance spectra of ordinary (H, L and LL) chondrites from the study of Dunn et al. (2010), which we resampled to the NIRS wavelength range. Using spectral parameters extracted from these resampled spectra we established a relationship between band parameters and their mafic silicate composition (olivine and low-Ca pyrox...

  2. Processes controlling the surface temperature signature of the Madden-Julian oscillation in the thermocline ridge of the Indian Ocean

    Energy Technology Data Exchange (ETDEWEB)

    Jayakumar, A.; Gnanaseelan, C. [Indian Institute of Tropical Meteorology, Pune (India); Vialard, Jerome; Lengaigne, M. [CNRS, UPMC, IRD, Case 100, Universite P. et M. Curie, Laboratoire d' Oceanographie Experimentation et Approches Numeriques, LOCEAN, Paris Cedex 05 (France); National Institute of Oceanography, Goa (India); McCreary, Julian P. [University of Hawaii, International Pacific Research Centre, Hawaii (United States); Praveen Kumar, B. [National Institute of Oceanography, Goa (India)

    2011-12-15

    During boreal winter, there is a prominent maximum of intraseasonal sea-surface temperature (SST) variability associated with the Madden-Julian Oscillation (MJO) along a Thermocline Ridge located in the southwestern Indian Ocean (5 S-10 S, 60 E-90 E; TRIO region). There is an ongoing debate about the relative importance of air-sea heat fluxes and oceanic processes in driving this intraseasonal SST variability. Furthermore, various studies have suggested that interannual variability of the oceanic structure in the TRIO region could modulate the amplitude of the MJO-driven SST response. In this study, we use observations and ocean general circulation model (OGCM) experiments to quantify these two effects over the 1997-2006 period. Observational analysis indicates that Ekman pumping does not contribute significantly (on average) to intraseasonal SST variability. It is, however, difficult to quantify the relative contribution of net heat fluxes and entrainment to SST intraseasonal variability from observations alone. We therefore use a suite of OGCM experiments to isolate the impacts of each process. During 1997-2006, wind stress contributed on average only about 20% of the intraseasonal SST variability (averaged over the TRIO region), while heat fluxes contributed about 70%, with forcing by shortwave radiation (75%) dominating the other flux components (25%). This estimate is consistent with an independent air-sea flux product, which indicates that shortwave radiation contributes 68% of intraseasonal heat flux variability. The time scale of the heat-flux perturbation, in addition to its amplitude, is also important in controlling the intraseasonal SST signature, with longer periods favouring a larger response. There are also strong year-to-year variations in the respective role of heat fluxes and wind stress. Of the five strong cooling events identified in both observations and the model (two in 1999 and one in 2000, 2001 and 2002), intraseasonal-wind stress dominates

  3. Spectral Analysis of Surface Features of Subaquaeous Pyroclastic Flow Deposits Around Santorini Volcano, Greece

    Science.gov (United States)

    Croff, K. L.; Sigurdsson, H.; Carey, S.; Alexandri, M.; Sakellariou, D.; Nomikou, P.

    2006-12-01

    Multibeam bathymetry mapping and seismic airgun surveys of the submarine region around the Santorini volcanic field in the Hellenic Arc (Greece) have revealed regions of terraced or step-like topography. These features may be related to the transport and deposition of submarine pyroclastic flows from the last major eruption of this volcano (~3600yrs. B.P.). The uppermost sediment sequence identified in seismic records has an average thickness of approximately 29 meters and may represent the pyroclastic flow deposits from this eruption. These terraced or step-like features are mainly located in areas that are approximately five kilometers offshore and at depths in the range of 200 to 800 meters. The seafloor in these areas has slope ratios on the order of 1:20. Profiles of the seafloor topography were sampled from seismic profiles that radiate from the Sanotrini caldera in five regions of interest. Spectral analysis of seafloor topography has been carried out to determine spectral characteristics of these features, including power spectrum, periodicity and amplitude of the waveforms, variance, and roughness of topography. The results are compared to surface features of the subaqueous pyroclastic deposits from the 1883 explosive eruption of Krakatau (Indonesia) and other areas with similar environments, to determine the parameters that are characteristic of this new feature of submarine volcaniclastic deposits.

  4. The impact of grid and spectral nudging on the variance of the near-surface wind speed

    DEFF Research Database (Denmark)

    Vincent, Claire Louise; Hahmann, Andrea N.

    2015-01-01

    variance in the Weather Research and Forecasting model is analyzed. Simulations are run on nested domains with horizontal grid spacing 15 and 5 km over the Baltic Sea region. For the 15 km domain, 36-hr simulations initialized each day are compared with 11-day simulations with either grid or spectral......Grid and spectral nudging are effective ways of preventing drift from large scale weather patterns in regional climate models. However, the effect of nudging on the wind-speed variance is unclear. In this study, the impact of grid and spectral nudging on near-surface and upper boundary layer wind...

  5. Spectral Analysis of Surface Wave for Empirical Elastic Design of Anchored Foundations

    Directory of Open Access Journals (Sweden)

    S. E. Chen

    2012-01-01

    Full Text Available Helical anchors are vital support components for power transmission lines. Failure of a single anchor can lead to the loss of an entire transmission line structure which results in the loss of power for downstream community. Despite being important, it is not practical to use conventional borehole method of subsurface exploration, which is labor intensive and costly, for estimating soil properties and anchor holding capacity. This paper describes the use of an empirical and elasticity-based design technique coupled with the spectral analysis of surface wave (SASW technique to provide subsurface information for anchor foundation designs. Based on small-strain wave propagation, SASW determines shear wave velocity profile which is then correlated to anchor holding capacity. A pilot project involving over 400 anchor installations has been performed and demonstrated that such technique is reliable and can be implemented into transmission line structure designs.

  6. Spatial Downscaling Research of Satellite Land Surface Temperature Based on Spectral Normalization Index

    Directory of Open Access Journals (Sweden)

    LI Xiaojun

    2017-03-01

    Full Text Available Aiming at the problem that the spatial and temporal resolution of land surface temperature (LST have the contradiction with each other, a new downscaling model was put forward, based on the TsHARP(an algorithm for sharpening thermal imagery downscaling method, this research makes improvements by selecting the better correlation of spectral index(normalized difference vegetation index, NDVI; normalized difference build-up index, NDBI; modified normalized difference water index, MNDWI; enhanced bare soil index, EBSI with LST, i.e., replaces the original NDVI with new spectral index according to the different surface land-cover types, to assess the accuracy of each downscaling method based on qualitative and quantitative analysis with synchronous Landsat 8 TIRS LST data. The results show that both models could effectively enhance the spatial resolution while simultaneously preserving the characteristics and spatial distribution of the original 1 km MODIS LST image, and also eliminate the “mosaic” effect in the original 1 km image, both models were proved to be effective and applicable in our study area; global scale analysis shows that the new model (RMSE:1.635℃ is better than the TsHARP method (RMSE:2.736℃ in terms of the spatial variability and accuracy of the results; the different land-cover types of downscaling statistical analysis shows that the TsHARP method has poor downscaling results in the low vegetation coverage area, especially for the bare land and building-up area(|MBE|>3℃, the new model has obvious advantages in the description of the low vegetation coverage area. Seasonal analysis shows that the downscaling results of two models in summer and autumn are superior to those in spring and winter, the new model downscaling results are better than the TsHARP method in the four seasons, in which the spring and winter downscaling improvement is better than summer and autumn.

  7. Surface Plasmon-Assisted Excitation of Atomic Visible Light Spectral Lines in the Impact of Highly Charged Ions 126Xeq+ on Solid Surfaces

    Institute of Scientific and Technical Information of China (English)

    张小安; 赵永涛; 李福利; 杨治虎; 肖国青; 詹文龙

    2003-01-01

    We measured the visible light spectral lines of sputtering atoms from solid surfaces of Al, Ti, Ni, Ta and Au which are impacted by 150keV126Xeq+ (6≤q≤30). It is found that intensities of the light spectral lines are greatly and suddenly enhanced when the charge state of the ion is raised up to a critical value. If assuming that potential energy released from the incidention due to capturing one electron is enough to excite a surface plasmon, we can estimate the critical charge states and obtain the results very well consistent with the measurements for the above-mentioned target materials. This means that a surface plasmon induced by one electron capture can enhance the excitation of atomic visible light spectral lines in the impact of a highly charged ion on a solid surface.

  8. High surface magnetic field in red giants as a new signature of planet engulfment?

    CERN Document Server

    Privitera, Giovanni; Eggenberger, Patrick; Georgy, Cyril; Ekström, Sylvia; Vidotto, Aline A; Bianda, Michele; Villaver, Eva; ud-Doula, Asif

    2016-01-01

    Context. Red-giant stars may engulf planets. This may increase the rotation rate of their convective envelope, which could lead to strong dynamo-triggered magnetic fields. Aims. We explore the possibility of generating magnetic fields in red giants that have gone through the process of a planet engulfment. We compare them with similar models that evolve without any planets. We discuss the impact of stellar wind magnetic braking on the evolution of the surface velocity of the parent star. Methods. With rotating stellar models with and without planets and an empirical relation between the Rossby number and the surface magnetic field, we deduce the evolution of the surface magnetic field along the red-giant branch. The effects of wind magnetic braking is explored using a relation deduced from MHD simulations. Results. The stellar evolution model of a 1.7 M$_\\odot$ without planet engulfment and that has a time-averaged rotation velocity during the Main-Sequence equal to 100 km s$^{-1}$, shows a surface magnetic f...

  9. Mineralogical, geochemical, and magnetic signatures of surface sediments from the Canadian Beaufort Shelf and Amundsen Gulf (Canadian Arctic)

    Science.gov (United States)

    Gamboa, Adriana; Montero-Serrano, Jean-Carlos; St-Onge, Guillaume; Rochon, André; Desiage, Pierre-Arnaud

    2017-02-01

    Mineralogical, geochemical, magnetic, and siliciclastic grain-size signatures of 34 surface sediment samples from the Mackenzie-Beaufort Sea Slope and Amundsen Gulf were studied in order to better constrain the redox status, detrital particle provenance, and sediment dynamics in the western Canadian Arctic. Redox-sensitive elements (Mn, Fe, V, Cr, Zn) indicate that modern sedimentary deposition within the Mackenzie-Beaufort Sea Slope and Amundsen Gulf took place under oxic bottom-water conditions, with more turbulent mixing conditions and thus a well-oxygenated water column prevailing within the Amundsen Gulf. The analytical data obtained, combined with multivariate statistical (notably, principal component and fuzzy c-means clustering analyses) and spatial analyses, allowed the division of the study area into four provinces with distinct sedimentary compositions: (1) the Mackenzie Trough-Canadian Beaufort Shelf with high phyllosilicate-Fe oxide-magnetite and Al-K-Ti-Fe-Cr-V-Zn-P contents; (2) Southwestern Banks Island, characterized by high dolomite-K-feldspar and Ca-Mg-LOI contents; (3) the Central Amundsen Gulf, a transitional zone typified by intermediate phyllosilicate-magnetite-K-feldspar-dolomite and Al-K-Ti-Fe-Mn-V-Zn-Sr-Ca-Mg-LOI contents; and (4) mud volcanoes on the Canadian Beaufort Shelf distinguished by poorly sorted coarse-silt with high quartz-plagioclase-authigenic carbonate and Si-Zr contents, as well as high magnetic susceptibility. Our results also confirm that the present-day sedimentary dynamics on the Canadian Beaufort Shelf is mainly controlled by sediment supply from the Mackenzie River. Overall, these insights provide a basis for future studies using mineralogical, geochemical, and magnetic signatures of Canadian Arctic sediments in order to reconstruct past variations in sediment inputs and transport pathways related to late Quaternary climate and oceanographic changes.

  10. Impacts of coal dust from an active mine on the spectral reflectance of Arctic surface snow in Svalbard, Norway

    Science.gov (United States)

    Khan, Alia L.; Dierssen, Heidi; Schwarz, Joshua P.; Schmitt, Carl; Chlus, Adam; Hermanson, Mark; Painter, Thomas H.; McKnight, Diane M.

    2017-02-01

    Light-absorbing particles (LAPs) in snow such as dust and black carbon influence the radiative forcing at the Earth's surface, which has major implications for global climate models. LAPs also significantly influence the melting of glaciers, sea ice, and seasonal snow. Here we present an in situ study of surface snow near an active coal mine in the Norwegian Arctic. We couple measurements of spectral hemispherical directional reflectance factor (HDRF) with measurements of LAPs characterized in two ways, as refractory black carbon using a Single Particle Soot Photometer and the total light absorption of LAPs measured with the Light Absorption Heating Method. The Snow Ice and Aerosol Radiation model was constrained by LAP measurements. Results were compared to observed spectral albedo measurements. Modeled and observed albedos were similar at the cleaner and more remote sites. However, the modeled spectral albedos do not fully account for the low spectral albedo measured next to the mine. LAP measurements also showed a large variation in particle sizes (tenths to tens of microns) related to transport distance of the particles from the mine. Here we find that LAPs from coal dust reduce the spectral HDRF by up to 84% next to the mine and 55% 0.5 km downwind of the mine. The coupling of extreme LAP observations (1 ng g-1 to 4863 ng g-1) with HDRF measurements from 350 to 2500 nm has facilitated the development of spectral band pairs, which could be used in the future to remotely assess LAPs in Arctic snow.

  11. Comparisons Between Model Predictions and Spectral Measurements of Charged and Neutral Particles on the Martian Surface

    Science.gov (United States)

    Kim, Myung-Hee Y.; Cucinotta, Francis A.; Zeitlin, Cary; Hassler, Donald M.; Ehresmann, Bent; Rafkin, Scot C. R.; Wimmer-Schweingruber, Robert F.; Boettcher, Stephan; Boehm, Eckart; Guo, Jingnan; hide

    2014-01-01

    Detailed measurements of the energetic particle radiation environment on the surface of Mars have been made by the Radiation Assessment Detector (RAD) on the Curiosity rover since August 2012. RAD is a particle detector that measures the energy spectrum of charged particles (10 to approx. 200 MeV/u) and high energy neutrons (approx 8 to 200 MeV). The data obtained on the surface of Mars for 300 sols are compared to the simulation results using the Badhwar-O'Neill galactic cosmic ray (GCR) environment model and the high-charge and energy transport (HZETRN) code. For the nuclear interactions of primary GCR through Mars atmosphere and Curiosity rover, the quantum multiple scattering theory of nuclear fragmentation (QMSFRG) is used. For describing the daily column depth of atmosphere, daily atmospheric pressure measurements at Gale Crater by the MSL Rover Environmental Monitoring Station (REMS) are implemented into transport calculations. Particle flux at RAD after traversing varying depths of atmosphere depends on the slant angles, and the model accounts for shielding of the RAD "E" dosimetry detector by the rest of the instrument. Detailed comparisons between model predictions and spectral data of various particle types provide the validation of radiation transport models, and suggest that future radiation environments on Mars can be predicted accurately. These contributions lend support to the understanding of radiation health risks to astronauts for the planning of various mission scenarios

  12. Spectral data of specular reflectance, narrow-angle transmittance and angle-resolved surface scattering of materials for solar concentrators.

    Science.gov (United States)

    Good, Philipp; Cooper, Thomas; Querci, Marco; Wiik, Nicolay; Ambrosetti, Gianluca; Steinfeld, Aldo

    2016-03-01

    The spectral specular reflectance of conventional and novel reflective materials for solar concentrators is measured with an acceptance angle of 17.5 mrad over the wavelength range 300-2500 nm at incidence angles 15-60° using a spectroscopic goniometry system. The same experimental setup is used to determine the spectral narrow-angle transmittance of semi-transparent materials for solar collector covers at incidence angles 0-60°. In addition, the angle-resolved surface scattering of reflective materials is recorded by an area-scan CCD detector over the spectral range 350-1050 nm. A comprehensive summary, discussion, and interpretation of the results are included in the associated research article "Spectral reflectance, transmittance, and angular scattering of materials for solar concentrators" in Solar Energy Materials and Solar Cells.

  13. Spectral data of specular reflectance, narrow-angle transmittance and angle-resolved surface scattering of materials for solar concentrators

    Directory of Open Access Journals (Sweden)

    Philipp Good

    2016-03-01

    Full Text Available The spectral specular reflectance of conventional and novel reflective materials for solar concentrators is measured with an acceptance angle of 17.5 mrad over the wavelength range 300−2500 nm at incidence angles 15–60° using a spectroscopic goniometry system. The same experimental setup is used to determine the spectral narrow-angle transmittance of semi-transparent materials for solar collector covers at incidence angles 0–60°. In addition, the angle-resolved surface scattering of reflective materials is recorded by an area-scan CCD detector over the spectral range 350–1050 nm. A comprehensive summary, discussion, and interpretation of the results are included in the associated research article “Spectral reflectance, transmittance, and angular scattering of materials for solar concentrators” in Solar Energy Materials and Solar Cells.

  14. Understanding wetland sub-surface hydrology using geologic and isotopic signatures

    Directory of Open Access Journals (Sweden)

    P. K. Sikdar

    2009-04-01

    Full Text Available This paper attempts to utilize hydrogeoloy and isotope composition of groundwater to understand the present hydrological processes prevalent in a freshwater wetland, source of wetland groundwater, surface water/groundwater interaction and mixing of groundwater of various depth zones in the aquifer. This study considers East Calcutta Wetlands (ECW – a freshwater peri-urban inland wetland ecosystem located at the lower part of the deltaic alluvial plain of South Bengal Basin and east of Kolkata city. This wetland is well known over the world for its resource recovery systems, developed by local people through ages, using wastewater from the city. Geological investigations reveal that the sub-surface geology is completely blanketed by the Quaternary sediments comprising a succession of silty clay, sand of various grades and sand mixed with occasional gravels and thin intercalations of silty clay. Aquifer within the depths of 80 m to 120 m has the maximum potential to supply water. Groundwater mainly flows from east to west and is being over-extracted to the tune of 65×103 m3/day. δ18O and δD values of shallow and deep groundwater are similar indicating resemblance in hydrostratigraphy and climate of the recharge areas. Groundwater originates mainly from monsoonal rain with some evaporation prior to or during infiltration and partly from bottom of ponds, canals and infiltration of groundwater withdrawn for irrigation. Relatively high tritium content of the shallow groundwater indicates local recharge, while the deeper groundwater with very low tritium is recharged mainly from distant areas. At places the deeper aquifer has relatively high tritium, indicating mixing of groundwater of shallow and deep aquifers. Metals such as copper, lead, arsenic, cadmium, aluminum, nickel and chromium are also present in groundwater of various depths. Therefore, aquifers of wetland and surrounding urban areas which are heavily

  15. Understanding wetland sub-surface hydrology using geologic and isotopic signatures

    Directory of Open Access Journals (Sweden)

    P. Sahu

    2009-07-01

    Full Text Available This paper attempts to utilize hydrogeology and isotope composition of groundwater to understand the present hydrological processes prevalent in a freshwater wetland, source of wetland groundwater, surface water/groundwater interaction and mixing of groundwater of various depth zones in the aquifer. This study considers East Calcutta Wetlands (ECW – a freshwater peri-urban inland wetland ecosystem located at the lower part of the deltaic alluvial plain of South Bengal Basin and east of Kolkata city. This wetland is well known over the world for its resource recovery systems, developed by local people through ages, using wastewater of the city. Geological investigations reveal that the sub-surface geology is completely blanketed by the Quaternary sediments comprising a succession of silty clay, sand of various grades and sand mixed with occasional gravels and thin intercalations of silty clay. At few places the top silty clay layer is absent due to scouring action of past channels. In these areas sand is present throughout the geological column and the areas are vulnerable to groundwater pollution. Groundwater mainly flows from east to west and is being over-extracted to the tune of 65×103 m3/day. δ18O and δD values of shallow and deep groundwater are similar indicating resemblance in hydrostratigraphy and climate of the recharge areas. Groundwater originates mainly from monsoonal rain with some evaporation prior to or during infiltration and partly from bottom of ponds, canals and infiltration of groundwater withdrawn for irrigation. Relatively high tritium content of the shallow groundwater indicates local recharge, while the deep groundwater with very low tritium is recharged mainly from distant areas. At places the deep aquifer has relatively high tritium, indicating mixing of groundwater of shallow and deep aquifers. Metals such as copper, lead, arsenic, cadmium, aluminium, nickel and chromium are also

  16. Comparison of TOMS retrievals and UVMRP measurements of surface spectral UV radiation in the United States

    Directory of Open Access Journals (Sweden)

    M. Xu

    2010-09-01

    Full Text Available Surface noontime spectral ultraviolet (UV irradiances during May-September of 2000–2004 from the total ozone mapping spectrometer (TOMS satellite retrievals are systematically compared with the ground measurements at 27 climatological sites maintained by the USDA UV-B Monitoring and Research Program. The TOMS retrievals are evaluated by two cloud screening methods and local air quality conditions to determine their bias dependencies on spectral bands, cloudiness, aerosol loadings, and air pollution. Under clear-sky conditions, TOMS retrieval biases vary from −3.4% (underestimation to 23.6% (overestimation. Averaged over all sites, the relative mean biases for 305, 311, 325, and 368 nm are respectively 15.4, 7.9, 7.6, and 7.0% (overestimation. The bias enhancement for 305 nm by approximately twice that of other bands likely results from absorption by gaseous pollutants (SO2, O3, and aerosols that are not included in the TOMS algorithm. For all bands, strong positive correlations of the TOMS biases are identified with aerosol optical depth, which explains nearly 50% of the variances of TOMS biases. The more restrictive in-situ cloud screening method reduces the biases by 3.4–3.9% averaged over all sites. This suggests that the TOMS biases from the in-situ cloud contamination may account for approximately 25% for 305 nm and 50% for other bands of the total bias. The correlation coefficients between total-sky and clear-sky biases across 27 sites are 0.92, 0.89, 0.83, and 0.78 for 305, 311, 325, and 368 nm, respectively. The results show that the spatial characteristics of the TOMS retrieval biases are systematic, representative of both clear and total-sky conditions.

  17. Multi-Spectral Satellite Imagery and Land Surface Modeling Supporting Dust Detection and Forecasting

    Science.gov (United States)

    Molthan, A.; Case, J.; Zavodsky, B.; Naeger, A. R.; LaFontaine, F.; Smith, M. R.

    2014-12-01

    Current and future multi-spectral satellite sensors provide numerous means and methods for identifying hazards associated with polluting aerosols and dust. For over a decade, the NASA Short-term Prediction Research and Transition (SPoRT) Center at Marshall Space Flight Center in Huntsville has focused on developing new applications from near real-time data sources in support of the operational weather forecasting community. The SPoRT Center achieves these goals by matching appropriate analysis tools, modeling outputs, and other products to forecast challenges, along with appropriate training and end-user feedback to ensure a successful transition. As a spinoff of these capabilities, the SPoRT Center has recently focused on developing collaborations to address challenges with the public health community, specifically focused on the identification of hazards associated with dust and pollution aerosols. Using multispectral satellite data from the SEVIRI instrument on the Meteosat series, the SPoRT team has leveraged EUMETSAT techniques for identifying dust through false color (RGB) composites, which have been used by the National Hurricane Center and other meteorological centers to identify, monitor, and predict the movement of dust aloft. Similar products have also been developed from the MODIS and VIIRS instruments onboard the Terra and Aqua, and Suomi-NPP satellites, respectively, and transitioned for operational forecasting use by offices within NOAA's National Weather Service. In addition, the SPoRT Center incorporates satellite-derived vegetation information and land surface modeling to create high-resolution analyses of soil moisture and other land surface conditions relevant to the lofting of wind-blown dust and identification of other, possible public-health vectors. Examples of land surface modeling and relevant predictions are shown in the context of operational decision making by forecast centers with potential future applications to public health arenas.

  18. Model to explain the effects of halide ions on the increase in surface enhanced Raman spectral intensity over time

    Science.gov (United States)

    Cole, Michael A.

    Understanding the mechanisms responsible for the large increase in spectral intensity when molecules are adsorbed to nanoparticle surfaces such as occurs during surface enhanced Raman (SER) spectroscopy will allow scientists to probe ever smaller scales, even allowing single molecule detection. One particular scenario that increased the SER scattering efficiency was the addition of halide ions to Rhodamine 6G (R6G)-ethanol solution. This thesis presents a theoretical model explaining the effects of halide ions on the SER spectral intensity of the Rhodamine 6G (R6G) molecule when co-adsorbed to a silver nanoparticle surface. Glaspell et al. 2005, found a linear correlation between the increase in spectral intensities of selected vibrational normal modes of R6G over time and the polarizabilities of co-adsorbed halide ions. When the R6G molecule co-adsorbs to the silver nanoparticle surface with the halide ions, the molecule is exposed to three external electric fields that add vectorially, creating a total external electric field. Modelling the fields from the halide ions and the silver nanoparticles as electric dipole fields introduces the polarizability of the halide ion linearly into the Raman spectral intensity equation. This model also shows that there is a necessary interaction between the halide ions and the silver nanoparticle surface in order to see the effects as described by Glaspell et al. Furthermore, we will present experimental results that show that there is a necessary interaction between the halide ions and the nanoparticle surface. Without this interaction there was no increase in the SER spectral intensity of R6G or pyridine molecules in solution with the halide ions but without the silver nanoparticles.

  19. Integrating seasonal optical and thermal infrared spectra to characterize urban impervious surfaces with extreme spectral complexity: a Shanghai case study

    Science.gov (United States)

    Wang, Wei; Yao, Xinfeng; Ji, Minhe

    2016-01-01

    Despite recent rapid advancement in remote sensing technology, accurate mapping of the urban landscape in China still faces a great challenge due to unusually high spectral complexity in many big cities. Much of this complication comes from severe spectral confusion of impervious surfaces with polluted water bodies and bright bare soils. This paper proposes a two-step land cover decomposition method, which combines optical and thermal spectra from different seasons to cope with the issue of urban spectral complexity. First, a linear spectral mixture analysis was employed to generate fraction images for three preliminary endmembers (high albedo, low albedo, and vegetation). Seasonal change analysis on land surface temperature induced from thermal infrared spectra and coarse component fractions obtained from the first step was then used to reduce the confusion between impervious surfaces and nonimpervious materials. This method was tested with two-date Landsat multispectral data in Shanghai, one of China's megacities. The results showed that the method was capable of consistently estimating impervious surfaces in highly complex urban environments with an accuracy of R2 greater than 0.70 and both root mean square error and mean average error less than 0.20 for all test sites. This strategy seemed very promising for landscape mapping of complex urban areas.

  20. Signature Balancing

    NARCIS (Netherlands)

    Noordkamp, H.W.; Brink, M. van den

    2006-01-01

    Signatures are an important part of the design of a ship. In an ideal situation, signatures must be as low as possible. However, due to budget constraints it is most unlikely to reach this ideal situation. The arising question is which levels of signatures are optimal given the different scenarios i

  1. Effect of spectral range in surface inactivation of Listeria innocua using broad-spectrum pulsed light.

    Science.gov (United States)

    Woodling, Sarah E; Moraru, Carmen I

    2007-04-01

    Pulsed light (PL) treatment is an alternative to traditional thermal treatment that has the potential to achieve several log-cycle reductions in the concentration of microorganisms. One issue that is still debated is related to what specifically causes cell death after PL treatments. The main objective of this work was to elucidate which portions of the PL range are responsible for bacterial inactivation. Stainless steel coupons with controlled surface properties were inoculated with a known concentration of Listeria innocua in the stationary growth phase and treated with 1 to 12 pulses of light at a pulse rate of 3 pulses per s and a pulse width of 360 micros. The effects of the full spectrum (lambda = 180 to 1,100 nm) were compared with the effects obtained when only certain regions of UV, visible, and near-infrared light were used. The effectiveness of the treatments was determined in parallel by the standard plate count and most-probable-number techniques. At a fluence of about 6 J/cm(2), the full-spectrum PL treatment resulted in a 4.08-log reduction of L. innocua on a Mill finish surface, the removal of lambda light resulted in no lethal effects on L. innocua. Overwhelmingly, the portions of the PL spectrum responsible for bacterial death are the UV-B and UV-C spectral ranges (X light (lambda > 400 nm). This work provides additional supporting evidence that cell death in PL treatment is due to exposure to UV light. Additionally, it was shown that even a minor modification of the light path or the UV light spectrum in PL treatments can have a significant negative impact on the treatment intensity and effectiveness.

  2. Study of land surface temperature and spectral emissivity using multi-sensor satellite data

    Indian Academy of Sciences (India)

    P K Srivastava; T J Majumdar; Amit K Bhattacharya

    2010-02-01

    In this study, an attempt has been made to estimate land surface temperatures (LST) and spectral emissivities over a hard rock terrain using multi-sensor satellite data. The study area, of about 6000 km2, is a part of Singhbhum–Orissa craton situated in the eastern part of India. TIR data from ASTER, MODIS and Landsat ETM+ have been used in the present study. Telatemp Model AG-42D Portable Infrared Thermometer was used for ground measurements to validate the results derived from satellite (MODIS/ASTER) data. LSTs derived using Landsat ETM+ data of two different dates have been compared with the satellite data (ASTER and MODIS) of those two dates. Various techniques, viz., temperature and emissivity separation (TES) algorithm, gray body adjustment approach in TES algorithm, Split-Window algorithms and Single Channel algorithm along with NDVI based emissivity approach have been used. LSTs derived from bands 31 and 32 of MODIS data using Split-Window algorithms with higher viewing angle (50°) (LST1 and LST2) are found to have closer agreement with ground temperature measurements (ground LST) over waterbody, Dalma forest and Simlipal forest, than that derived from ASTER data (TES with AST 13). However, over agriculture land, there is some uncertainty and difference between the measured and the estimated LSTs for both validation dates for all the derived LSTs. LST obtained using Single Channel algorithm with NDVI based emissivity method in channel 13 of ASTER data has yielded closer agreement with ground measurements recorded over vegetation and mixed lands of low spectral contrast. LST results obtained with TIR band 6 of Landsat ETM+ using Single Channel algorithm show close agreement over Dalma forest, Simlipal forest and waterbody with LSTs obtained using MODIS and ASTER data for a different date. Comparison of LSTs shows good agreement with ground measurements in thermally homogeneous area. However, results in agriculture area with less homogeneity show

  3. X-RAY SPECTRAL RESIDUALS IN NGC 5408 X-1: DIFFUSE EMISSION FROM STAR FORMATION, OR THE SIGNATURE OF A SUPER-EDDINGTON WIND?

    Energy Technology Data Exchange (ETDEWEB)

    Sutton, Andrew D [Astrophysics Office, NASA Marshall Space Flight Center, ZP12, Huntsville, Al 35812 (United States); Roberts, Timothy P. [Centre for Extragalactic Astronomy, Department of Physics, University of Durham, South Road, Durham, DH1 3LE (United Kingdom); Middleton, Matthew J, E-mail: andrew.d.sutton@nasa.gov [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge, CB3 0HA (United Kingdom)

    2015-11-20

    If ultraluminous X-ray sources (ULXs) are powered by accretion onto stellar remnant black holes, then many must be accreting at super-Eddington rates. It is predicted that such high accretion rates should give rise to massive, radiatively driven winds. However, observational evidence of a wind, in the form of absorption or emission features, has remained elusive. As such, the reported detection of X-ray spectral residuals in XMM-Newton spectra of NGC 5408 X-1, which could be related to absorption in a wind is potentially very exciting. However, it has previously been assumed by several authors that these features simply originate from background diffuse plasma emission related to star formation in the ULX’s host galaxy. In this work we utilize the spatial resolving power of Chandra to test whether we can rule out this latter interpretation. We demonstrate that the majority of the luminosity in these spectral features is emitted from a highly localized region close to the ULX, and appears point-like even with Chandra. It is therefore highly likely that the spectral features are associated with the ULX itself, and little of the flux in this spectral component originates from spatially extended emission in the host galaxy. This may be consistent with the suggestion of absorption in an optically thin phase of a super-Eddington wind. Alternatively, we could be seeing emission from collisionally ionized material close to the black hole, but critically this would be difficult to reconcile with models where the source inclination largely determines the observed X-ray spectral and timing properties.

  4. The Hubble Wide Field Camera 3 Test of Surfaces in the Outer Solar System: Spectral Variation on Kuiper Belt Objects

    CERN Document Server

    Fraser, Wesley C; Glass, Florian

    2015-01-01

    Here we present additional photometry of targets observed as part of the Hubble Wide Field Camera 3 Test of Surfaces in the Outer Solar System. 12 targets were re-observed with the Wide Field Camera 3 in optical and NIR wavebands designed to compliment those used during the first visit. Additionally, all observations originally presented by Fraser and Brown (2012) were reanalyzed through the same updated photometry pipeline. A reanalysis of the optical and NIR colour distribution reveals a bifurcated optical colour distribution and only two identifiable spectral classes, each of which occupies a broad range of colours and have correlated optical and NIR colours, in agreement with our previous findings. We report the detection of significant spectral variations on 5 targets which cannot be attributed to photometry errors, cosmic rays, point spread function or sensitivity variations, or other image artifacts capable of explaining the magnitude of the variation. The spectrally variable objects are found to have ...

  5. Spectral Reflectance Characteristics of Different Snow and Snow-Covered Land Surface Objects and Mixed Spectrum Fitting

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jia-hua; ZHOU Zheng-ming; WANG Pei-juan; YAO Feng-mei; Liming Yang

    2011-01-01

    The field spectroradiometer was used to measure spectra of different snow and snow-covered land surface objects in Beijing area.The result showed that for a pure snow spectrum,the snow reflectance peaks appeared from visible to 800 nm band locations; there was an obvious absorption valley of snow spectrum near 1 030 nm wavelength.Compared with fresh snow,the reflection peaks of the old snow and melting snow showed different degrees of decline in the ranges of 300~1 300,1 700~1 800 and 2 200~2 300 nm,the lowest was from the compacted snow and frozen ice.For the vegetation and snow mixed spectral characteristics,it was indicated that the spectral reflectance increased for the snow-covered land types (including pine leaf with snow and pine leaf on snow background),due to the influence of snow background in the range of 350~1 300 nm.However,the spectrum reflectance of mixed pixel remained a vegetation spectral characteristic.In the end,based on the spectrum analysis of snow,vegetation,and mixed snow/vegetation pixels,the mixed spectral fitting equations were established,and the results showed that there was good correlation between spectral curves by simulation fitting and observed ones (correlation coefficient R2 =0.950 9).

  6. Spectral reflectance characteristics of different snow and snow-covered land surface objects and mixed spectrum fitting.

    Science.gov (United States)

    Zhang, Jia-Hua; Zhou, Zheng-Ming; Wang, Pei-Juan; Yao, Feng-Mei; Liming, Yang

    2011-09-01

    The field spectroradiometer was used to measure spectra of different snow and snow-covered land surface objects in Beijing area. The result showed that for a pure snow spectrum, the snow reflectance peaks appeared from visible to 800 nm band locations; there was an obvious absorption valley of snow spectrum near 1 030 nm wavelength. Compared with fresh snow, the reflection peaks of the old snow and melting snow showed different degrees of decline in the ranges of 300-1 300, 1 700-1 800 and 2 200-2 300 nm, the lowest was from the compacted snow and frozen ice. For the vegetation and snow mixed spectral characteristics, it was indicated that the spectral reflectance increased for the snow-covered land types (including pine leaf with snow and pine leaf on snow background), due to the influence of snow background in the range of 350-1 300 nm. However, the spectrum reflectance of mixed pixel remained a vegetation spectral characteristic. In the end, based on the spectrum analysis of snow, vegetation, and mixed snow/vegetation pixels, the mixed spectral fitting equations were established, and the results showed that there was good correlation between spectral curves by simulation fitting and observed ones (correlation coefficient R2 = 0.950 9).

  7. A comparison of surface topography characterization technologies for use in comparing spent bullet and cartridge case signatures

    Energy Technology Data Exchange (ETDEWEB)

    Batishko, C.R.; Hickman, B.J.; Cuta, F.M.

    1992-11-01

    The Pacific Northwest Laboratory was tasked by the US Department of Energy to provide technical assistance to the Federal Bureau of Investigation in evaluating and ranking technologies potentially useful in high-speed comparison of unique spent bullet and cartridge case surface signatures. Information sources included vendor input, current relevant literature, vendor phone contacts, other FBI resources, relevant PNL reports, and personal contact with numerous PNL technical staff. A comprehensive list of technologies was reduced to a list of 38 by grouping very similar methodologies, and further reduced to a short list of six by applying a set of five minimum functional requirements. A total of 14 primary criteria, many having secondary criteria, were subsequently used to evaluate each technology. The ranked short list results are reported and supported in this document, and their scores normalized to a hypothetical ideal system are as follows: (1) confocal microscopy 82.13; (2) laser dynamic focusing 72.04; (3)moire interferometry V70.94; (4)fringe field capacitance;(5)laser triangulation 66.18; (6)structured/sectioned light 65.55. Information available within the time/budget constraints which was used for the evaluation and ranking was not sufficiently detailed to evaluate specific implementations of the technologies. Each of the technologies in the short list was judged potentially capable of meeting the minimum requirements. Clever, novel engineering solutions resulting in a more cost-effective system, or a closer fit to the ``ideal system,`` could result in a reordering of the short list when actual technical proposals are evaluated. Therefore, it is recommended that a Request for Proposal not be limited to only the highest ranked technology, but include all six technologies in the short list.

  8. A comparison of surface topography characterization technologies for use in comparing spent bullet and cartridge case signatures

    Energy Technology Data Exchange (ETDEWEB)

    Batishko, C.R.; Hickman, B.J.; Cuta, F.M.

    1992-11-01

    The Pacific Northwest Laboratory was tasked by the US Department of Energy to provide technical assistance to the Federal Bureau of Investigation in evaluating and ranking technologies potentially useful in high-speed comparison of unique spent bullet and cartridge case surface signatures. Information sources included vendor input, current relevant literature, vendor phone contacts, other FBI resources, relevant PNL reports, and personal contact with numerous PNL technical staff. A comprehensive list of technologies was reduced to a list of 38 by grouping very similar methodologies, and further reduced to a short list of six by applying a set of five minimum functional requirements. A total of 14 primary criteria, many having secondary criteria, were subsequently used to evaluate each technology. The ranked short list results are reported and supported in this document, and their scores normalized to a hypothetical ideal system are as follows: (1) confocal microscopy 82.13; (2) laser dynamic focusing 72.04; (3)moire interferometry V70.94; (4)fringe field capacitance;(5)laser triangulation 66.18; (6)structured/sectioned light 65.55. Information available within the time/budget constraints which was used for the evaluation and ranking was not sufficiently detailed to evaluate specific implementations of the technologies. Each of the technologies in the short list was judged potentially capable of meeting the minimum requirements. Clever, novel engineering solutions resulting in a more cost-effective system, or a closer fit to the ideal system,'' could result in a reordering of the short list when actual technical proposals are evaluated. Therefore, it is recommended that a Request for Proposal not be limited to only the highest ranked technology, but include all six technologies in the short list.

  9. Areal-averaged and Spectrally-resolved Surface Albedo from Ground-based Transmission Data Alone: Toward an Operational Retrieval

    Energy Technology Data Exchange (ETDEWEB)

    Kassianov, Evgueni I.; Barnard, James C.; Flynn, Connor J.; Riihimaki, Laura D.; Michalsky, Joseph; Hodges, G. B.

    2014-08-22

    We present here a simple retrieval of the areal-averaged and spectrally resolved surface albedo using only ground-based measurements of atmospheric transmission under fully overcast conditions. Our retrieval is based on a one-line equation and widely accepted assumptions regarding the weak spectral dependence of cloud optical properties in the visible and near-infrared spectral range. The feasibility of our approach for the routine determinations of albedo is demonstrated for different landscapes with various degrees of heterogeneity using three sets of measurements:(1) spectrally resolved atmospheric transmission from Multi-Filter Rotating Shadowband Radiometer (MFRSR) at wavelength 415, 500, 615, 673, and 870 nm, (2) tower-based measurements of local surface albedo at the same wavelengths, and (3) areal-averaged surface albedo at four wavelengths (470, 560, 670 and 860 nm) from collocated and coincident Moderate Resolution Imaging Spectroradiometer (MODIS) observations. These integrated datasets cover both long (2008-2013) and short (April-May, 2010) periods at the ARM Southern Great Plains (SGP) site and the NOAA Table Mountain site, respectively. The calculated root mean square error (RMSE), which is defined here as the root mean squared difference between the MODIS-derived surface albedo and the retrieved area-averaged albedo, is quite small (RMSE≤0.01) and comparable with that obtained previously by other investigators for the shortwave broadband albedo. Good agreement between the tower-based daily averages of surface albedo for the completely overcast and non-overcast conditions is also demonstrated. This agreement suggests that our retrieval originally developed for the overcast conditions likely will work for non-overcast conditions as well.

  10. Cell-surface marker signatures for the isolation of neural stem cells, glia and neurons derived from human pluripotent stem cells.

    Directory of Open Access Journals (Sweden)

    Shauna H Yuan

    Full Text Available BACKGROUND: Neural induction of human pluripotent stem cells often yields heterogeneous cell populations that can hamper quantitative and comparative analyses. There is a need for improved differentiation and enrichment procedures that generate highly pure populations of neural stem cells (NSC, glia and neurons. One way to address this problem is to identify cell-surface signatures that enable the isolation of these cell types from heterogeneous cell populations by fluorescence activated cell sorting (FACS. METHODOLOGY/PRINCIPAL FINDINGS: We performed an unbiased FACS- and image-based immunophenotyping analysis using 190 antibodies to cell surface markers on naïve human embryonic stem cells (hESC and cell derivatives from neural differentiation cultures. From this analysis we identified prospective cell surface signatures for the isolation of NSC, glia and neurons. We isolated a population of NSC that was CD184(+/CD271(-/CD44(-/CD24(+ from neural induction cultures of hESC and human induced pluripotent stem cells (hiPSC. Sorted NSC could be propagated for many passages and could differentiate to mixed cultures of neurons and glia in vitro and in vivo. A population of neurons that was CD184(-/CD44(-/CD15(LOW/CD24(+ and a population of glia that was CD184(+/CD44(+ were subsequently purified from cultures of differentiating NSC. Purified neurons were viable, expressed mature and subtype-specific neuronal markers, and could fire action potentials. Purified glia were mitotic and could mature to GFAP-expressing astrocytes in vitro and in vivo. CONCLUSIONS/SIGNIFICANCE: These findings illustrate the utility of immunophenotyping screens for the identification of cell surface signatures of neural cells derived from human pluripotent stem cells. These signatures can be used for isolating highly pure populations of viable NSC, glia and neurons by FACS. The methods described here will enable downstream studies that require consistent and defined neural

  11. Retrieval of soil erosion relevant parameters in the Western Australian wheat belt region from VNIR-SWIR and TIR spectral signatures

    OpenAIRE

    Andreas Eisele; Sabine Chabrillat; I. Lau; Kobayashi, C.; B. Wheaton; Carter, D.; Kashimura, O.; Kato, M.; Ong, C.; R. Hewson; Cudahy, T.; Hermann Kaufmann

    2011-01-01

    With the focus on new available hyperspectral imaging sensors sensitive within the thermal infrared (TIR) wavelength region, this study is testing the ability of the TIR in deriving soil erosion relevant parameters (e.g. texture, organic carbon content) from soil spectral measurements with the respect to commonly used VNIR-SWIR spectrometers. Therefore a study site was chosen located within an agricultural area in Western Australia, which is suffering from soil loss through wind erosion proce...

  12. Power spectral analysis of surface electromyography (EMG) at matched contraction levels of the first dorsal interosseous muscle in stroke survivors.

    Science.gov (United States)

    Li, Xiaoyan; Shin, Henry; Zhou, Ping; Niu, Xun; Liu, Jie; Rymer, William Zev

    2014-05-01

    The objective of this study was to help assess complex neural and muscular changes induced by stroke using power spectral analysis of surface electromyogram (EMG) signals. Fourteen stroke subjects participated in the study. They were instructed to perform isometric voluntary contractions by abducting the index finger. Surface EMG signals were collected from the paretic and contralateral first dorsal interosseous (FDI) muscles with forces ranging from 30% to 70% maximum voluntary contraction (MVC) of the paretic muscle. Power spectral analysis was performed to characterize features of the surface EMG in paretic and contralateral muscles at matched forces. A Linear Mixed Model was applied to identify the spectral changes in the hemiparetic muscle and to examine the relation between spectral parameters and contraction levels. Regression analysis was performed to examine the correlations between spectral characteristics and clinical features. Differences in power spectrum distribution patterns were observed in paretic muscles when compared with their contralateral pairs. Nine subjects showed increased mean power frequency (MPF) in the contralateral side (>15 Hz). No evident spectrum difference was observed in 3 subjects. Only 2 subjects had higher MPF in the paretic muscle than the contralateral muscle. Pooling all subjects' data, there was a significant reduction of MPF in the paretic muscle compared with the contralateral muscle (paretic: 168.7 ± 7.6 Hz, contralateral: 186.1 ± 8.7 Hz, mean ± standard error, F=36.56, ppower spectrum did not confirm a significant correlation between the MPF and contraction force in either hand (F=0.7, p>0.5). There was no correlation between spectrum difference and Fugl-Meyer or Chedoke scores, or ratio of paretic and contralateral MVC (p>0.2). There appears to be complex muscular and neural processes at work post stroke that may impact the surface EMG power spectrum. The majority of the tested stroke subjects had lower MPF in the

  13. Automated mapping of impervious surfaces in urban and suburban areas: Linear spectral unmixing of high spatial resolution imagery

    Science.gov (United States)

    Yang, Jian; He, Yuhong

    2017-02-01

    Quantifying impervious surfaces in urban and suburban areas is a key step toward a sustainable urban planning and management strategy. With the availability of fine-scale remote sensing imagery, automated mapping of impervious surfaces has attracted growing attention. However, the vast majority of existing studies have selected pixel-based and object-based methods for impervious surface mapping, with few adopting sub-pixel analysis of high spatial resolution imagery. This research makes use of a vegetation-bright impervious-dark impervious linear spectral mixture model to characterize urban and suburban surface components. A WorldView-3 image acquired on May 9th, 2015 is analyzed for its potential in automated unmixing of meaningful surface materials for two urban subsets and one suburban subset in Toronto, ON, Canada. Given the wide distribution of shadows in urban areas, the linear spectral unmixing is implemented in non-shadowed and shadowed areas separately for the two urban subsets. The results indicate that the accuracy of impervious surface mapping in suburban areas reaches up to 86.99%, much higher than the accuracies in urban areas (80.03% and 79.67%). Despite its merits in mapping accuracy and automation, the application of our proposed vegetation-bright impervious-dark impervious model to map impervious surfaces is limited due to the absence of soil component. To further extend the operational transferability of our proposed method, especially for the areas where plenty of bare soils exist during urbanization or reclamation, it is still of great necessity to mask out bare soils by automated classification prior to the implementation of linear spectral unmixing.

  14. Adaption of the MODIS aerosol retrieval algorithm by airborne spectral surface reflectance measurements over urban areas: a case study

    Directory of Open Access Journals (Sweden)

    E. Jäkel

    2015-07-01

    Full Text Available MODIS retrievals of the aerosol optical depth (AOD are biased over urban areas, where surface reflectance is not well characterized. Since the operational MODIS aerosol retrieval for dark targets assumes fixed spectral slopes to calculate the surface reflectance at 0.47 μm, the algorithm may fail in urban areas with different spectral characteristics of the surface reflectance. To investigate this bias we have implemented variable spectral slopes into the operational MODIS aerosol algorithms of Collection 5 (C5 and C6. The variation of slopes is based on airborne measurements of surface reflectances over the city of Zhongshan, China. AOD retrieval results of the operational and the modified algorithms were compared for a MODIS measurement over Zhongshan. For this case slightly lower AOD values were derived using the modified algorithm. The retrieval methods were additionally applied to MODIS data of the Beijing area for a period between 2010–2014 when also AERONET data were available. A reduction of the differences between the AOD retrieved using the modified C5 algorithm and AERONET was found, whereby the mean difference from 0.31 ± 0.11 for the operational C5 and 0.18 ± 0.12 for the operational C6 where reduced to a mean difference of 0.09 ± 0.18 by using the modified C5 retrieval. Furthermore, the sensitivity of the MODIS AOD retrieval for several surface types was investigated. Radiative transfer simulations were performed to model reflectances at top of atmosphere for predefined aerosol properties. The reflectances were used as input for the retrieval methods. It is shown that the operational MODIS AOD retrieval over land reproduces the AOD reference input of 0.85 for dark surface types [retrieved AOD = 0.87 (C5]. An overestimation of AOD = 0.99 is found for urban surfaces, whereby the modified C5 algorithm shows a good performance with a retrieved value of AOD = 0.86.

  15. Local Environment and Interactions of Liquid and Solid Interfaces Revealed by Spectral Line Shape of Surface Selective Nonlinear Vibrational Probe

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Shun-Li; Fu, Li; Chase, Zizwe A.; Gan, Wei; Wang, Hong-Fei

    2016-11-10

    Vibrational spectral lineshape contains important detailed information of molecular vibration and reports its specific interactions and couplings to its local environment. In this work, recently developed sub-1 cm-1 high-resolution broadband sum frequency generation vibrational spectroscopy (HR-BB-SFG-VS) was used to measure the -C≡N stretch vibration in the 4-n-octyl-4’-cyanobiphenyl (8CB) Langmuir or Langmuir-Blodgett (LB) monolayer as a unique vibrational probe, and the spectral lineshape analysis revealed the local environment and interactions at the air/water, air/glass, air/calcium fluoride and air/-quartz interfaces for the first time. The 8CB Langmuir or LB film is uniform and the vibrational spectral lineshape of its -C≡N group has been well characterized, making it a good choice as the surface vibrational probe. Lineshape analysis of the 8CB -C≡N stretch SFG vibrational spectra suggests the coherent vibrational dynamics and the structural and dynamic inhomogeneity of the -C≡N group at each interface are uniquely different. In addition, it is also found that there are significantly different roles for water molecules in the LB films on different substrate surfaces. These results demonstrated the novel capabilities of the surface nonlinear spectroscopy in characterization and in understanding the specific structures and chemical interactions at the liquid and solid interfaces in general.

  16. Polyhedral oligomeric silsesquioxane trisilanols as pigment surface modifiers for fluoropolymer based thickness sensitive spectrally selective (TSSS) paint coatings

    Energy Technology Data Exchange (ETDEWEB)

    Jerman, I.; Mihelcic, M.; Orel, B. [National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana (Slovenia); Verhovsek, D. [Cinkarna - METALURSKO KEMICNA INDUSTRIJA CELJE, d.d. Kidriceva 26, 3001 Celje (Slovenia); Kovac, J. [Jozef Stefan Institute, Jamova 39, 1000 Ljubljana (Slovenia)

    2011-02-15

    Thickness insensitive spectrally selective (TISS) paint coatings based on black pigment (PK 3060, Ferro Company) dispersed in a fluoropolymeric resin binder (Lumiflon, Asahi Company, Japan) have recently been made without added aluminium flakes and their properties have been reported for the first time. In this study we investigated in more detail the effect of trisilanol isobutyl (IB{sub 7} T{sub 7}(OH){sub 3}) polyhedral oligomeric silsesquioxane (trisilanol POSS) on the surface modification of PK 3060 pigment. Infrared spectral analysis of the surface modified pigment particles provided firm evidence for the formation of a POSS layer on the surface of the pigment particles, substantiated by the corresponding TEM and Energy Dispersive X-ray Spectroscopy (EDXS) measurements of functionalized and as-received pigments. SEM micrographs of the diluted dispersions in fluoropolymeric resin binder revealed uniform distribution of pigment particles with an average size of {proportional_to}300 nm and the beneficial effect of the pigment functionalization was assessed from the measured spectral selectivity of coatings of various thicknesses. (author)

  17. Impact of environmental factors on the spectral characteristics of lava surfaces:field spectrometry of basaltic lava flows on Tenerife, Canary Islands, Spain

    OpenAIRE

    Long Li; Carmen Solana; Frank Canters; Jonathan C.-W. Chan; Matthieu Kervyn

    2015-01-01

    We report on spectral reflectance measurements of basaltic lava flows on Tenerife Island, Spain. Lava flow surfaces of different ages, surface roughness and elevations were systematically measured using a field spectroradiometer operating in the range of 350–2500 nm. Surface roughness, oxidation and lichen coverage were documented at each measured site. Spectral properties vary with age and morphology of lava. Pre-historical lavas with no biological coverage show a prominent increase in spect...

  18. Areal-Averaged Spectral Surface Albedo from Ground-Based Transmission Data Alone: Toward an Operational Retrieval

    Directory of Open Access Journals (Sweden)

    Evgueni Kassianov

    2014-08-01

    Full Text Available We present here a simple retrieval of the areal-averaged spectral surface albedo using only ground-based measurements of atmospheric transmission under fully overcast conditions. Our retrieval is based on a one-line equation. The feasibility of our retrieval for routine determinations of albedo is demonstrated for different landscapes with various degrees of heterogeneity using three sets of measurements: (1 spectral atmospheric transmission from the Multi-Filter Rotating Shadowband Radiometer (MFRSR at five wavelengths (415, 500, 615, 673, and 870 nm; (2 tower-based measurements of local surface albedo at the same wavelengths; and (3 areal-averaged surface albedo at four wavelengths (470, 560, 670 and 860 nm from collocated and coincident Moderate Resolution Imaging Spectroradiometer (MODIS observations. These integrated datasets cover both temporally long (2008–2013 and short (April–May 2010 periods at the Atmospheric Radiation Measurement (ARM Southern Great Plains site and the National Oceanic and Atmospheric Administration (NOAA Table Mountain site, respectively. The calculated root mean square error (RMSE, defined here as the root mean squared difference between the MODIS-derived surface albedo and the retrieved areal-averaged albedo, is quite small (RMSE ≤ 0.015 and comparable with that obtained previously by other investigators for the shortwave broadband albedo. Good agreement between tower-based measurements of daily-averaged surface albedo for completely overcast and non-overcast conditions is also demonstrated.

  19. Optimization of spectral sensitivities of mosaic five-band camera for estimating chromophore densities from skin images including shading and surface reflections

    Science.gov (United States)

    Hirose, Misa; Akaho, Rina; Maita, Chikashi; Sugawara, Mai; Tsumura, Norimichi

    2016-06-01

    In this paper, the spectral sensitivities of a mosaic five-band camera were optimized using a numerical skin phantom to perform the separation of chromophore densities, shading and surface reflection. To simulate the numerical skin phantom, the spectral reflectance of skin was first calculated by Monte Carlo simulation of photon migration for different concentrations of melanin, blood and oxygen saturation levels. The melanin and hemoglobin concentration distributions used in the numerical skin phantom were obtained from actual skin images by independent component analysis. The calculated components were assigned as concentration distributions. The spectral sensitivities of the camera were then optimized using a nonlinear technique to estimate the spectral reflectance for skin separation. In this optimization, the spectral sensitivities were assumed to be normally distributed, and the sensor arrangement was identical to that of a conventional mosaic five-band camera. Our findings demonstrated that spectral estimation could be significantly improved by optimizing the spectral sensitivities.

  20. Initial analyses of surface spectral radiance between observations and Line-By-Line calculations

    Energy Technology Data Exchange (ETDEWEB)

    Brown, P.D.; Clough, S.A. [Atmospheric and Environmental Research, Inc., Cambridge, MA (United States); Miller, N.E.; Shippert, T.R.; Turner, D.D. [Pacific Northwest Lab., Richland, WA (United States)] [and others

    1996-04-01

    The evaluation an improvement of radiative transfer calculations are essential to attain improved performance of general circulation models (GCMs) for climate change applications. A Quality Measurement Experiment (QME) is being conducted to analyze the spectral residuals between the downwelling longwave radiance measured by the University of Wisconsin Atmospheric Emitted Radiance Interferometer (AERI) and spectral radiance calculated by the Line-By-Line Radiative Transfer Model (LBLRTM). The three critical components of this study are (1) the assessment of the quality of the high resolution AERI measurements, (2) the assessment of the ability to define the atmospheric state in the radiating column, and (3) the evaluation of the capability of LBLRTM. Validations have been performed on spectral radiance data, obtained from April 1994 through July 1994, through the analysis of the spectral interval and physical process. The results are archived as a function of time, enabling the retrieval of specific data and facilitating investigations and diurnal effects, seasonal effects, and longer-term trends. While the initial focus is restricted to clear-sky analyses, efforts are under way to include the effects of clouds and aerosols. Plans are well formulated for the extension of the current approach to the shortwave. An overview of the concept of the QME is described by Miller et al. (1994), and a detailed description of this study is provided by Clough et al. (1994).

  1. Red-Shift Effects in Surface Enhanced Raman Spectroscopy: Spectral or Intensity Dependence of the Near-Field?

    KAUST Repository

    Colas, Florent

    2016-06-06

    Optimum amplification in Surface Enhanced Raman Scattering (SERS) from individual nanoantennas is expected when the excitation is slightly blue-shifted with respect to the Localized Surface Plasmon Resonance (LSPR), so that the LSPR peak falls in the middle between the laser and the Stokes Raman emission. Recent experiments have shown when moving the excitation from the visible to the near-infrared that this rule of thumb is no more valid. The excitation has to be red-shifted with respect to the LSPR peak, up to 80nm, to obtain highest SERS. Such discrepancy is usually attributed to a Near-Field (NF) to Far-Field (FF) spectral shift. Here we critically discuss this hypothesis for the case of gold nanocylinders. By combining multi-wavelength excitation SERS experiments with numerical calculations, we show that the red-shift of the excitation energy does not originate from a spectral shift between the extinction (FF) and the near-field distribution (NF), which is found to be not larger than 10nm. Rather, it can be accounted for by looking at the peculiar spectral dependence of the near-field intensity on the cylinders diameter, characterized by an initial increase, up to 180nm diameter, followed by a decrease and a pronounced skewness.

  2. Spectral re-distribution and surface loss effects in Swift XRT (XMM-Newton EPIC) MOS CCDs

    CERN Document Server

    Short, A D; Turner, M J L

    2002-01-01

    In the course of testing and selecting the EPIC MOS CCDs for the XMM-Newton observatory, the developed a Monte-Carlo model of the CCD response. Among other things, this model was used to investigate surface loss effects evident at low energies. By fitting laboratory data, these losses were characterised as a simple function of X-ray interaction depth and this result enabled the spectral re-distribution itself to be modelled as a simple analytical function. Subsequently, this analytical function has been used to generate the response matrix for the EPIC MOS instruments and will now be employed to model the spectral re-distribution for the Swift XRT CCD.

  3. Fusion of spectral and shape features for identification of urban surface cover types using reflective and thermal hyperspectral data

    Science.gov (United States)

    Segl, K.; Roessner, S.; Heiden, U.; Kaufmann, H.

    The urban environment is characterized by an intense multifunctional use of available spaces, where the preservation of open green spaces is of special importance. For this purpose, area-wide urban biotope mapping based on CIR aerial photographs has been carried out for the large cities in Germany during the last 10 years. Because of dynamic urban development and high mapping costs, the municipal authorities are interested in effective methods for mapping urban surface cover types, which can be used for evaluation of ecological conditions in urban structures and supporting updates of biotope maps. Against this background, airborne hyperspectral remote sensing data of the DAIS 7915 instrument have been analyzed for a test site in the city of Dresden (Germany) with regard to their potential for automated material-oriented identification of urban surface cover types. Previous investigations have shown that the high spectral and spatial variabilities of these data require the development of special methods, which are capable of dealing with the resulting mixed-pixel problem in its specific characteristics in urban areas. Earlier, methodological developments led to an approach based on a combination of spectral classification and pixel-oriented unmixing techniques to facilitate sensible endmember selection based on the reflective bands of the DAIS instrument. This approach is now extended by a shape-based classification technique including the thermal bands of the DAIS instrument to improve the detection of buildings during the process of identifying seedling pixels, which represent the starting points for linear spectral unmixing. This new approach increases the reliability of differentiation between buildings and open spaces, leading to more accurate results for the spatial distribution of surface cover types. Thus, the new approach significantly enhances the exploitation of the information potential of the hyperspectral DAIS 7915 data for an area-wide identification

  4. Spectral Tagging

    Energy Technology Data Exchange (ETDEWEB)

    Smartt, Heidi A. [Sandia National Laboratories (United States)

    2003-05-01

    This research examines the feasibility of spectral tagging, which involves modifying the spectral signature of a target, e.g. by mixing an additive with the target's paint. The target is unchanged to the human eye, but the tag is revealed when viewed with a spectrometer. This project investigates a layer of security that is not obvious, and therefore easy to conceal. The result is a tagging mechanism that is difficult to counterfeit. Uniquely tagging an item is an area of need in safeguards and security and non-proliferation. The powdered forms of the minerals lapis lazuli and olivine were selected as the initial test tags due to their availability and uniqueness in the visible to near-infrared spectral region. They were mixed with paints and applied to steel. In order to verify the presence of the tags quantitatively, the data from the spectrometer was input into unmixing models and signal detection algorithms. The mixture with the best results was blue paint mixed with lapis lazuli and olivine. The tag had a 0% probability of false alarm and a 100% probability of detection. The research proved that spectral tagging is feasible, although certain tag/paint mixtures are more detectable than others.

  5. [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.

  6. ELECTRONIC SIGNATURES

    African Journals Online (AJOL)

    10332324

    'electronic signature' means data attached to, incorporated in, or logically ... See Cwele v S 2012 4 All SA 497 (SCA); Mohlabeng v Minister of Safety and Security ... ZAKZPHC 51 (2 September 2010); Delta Finance, a Division of Wesbank, ...

  7. The Signature Sequence Region of the Human Drug Transporter Organic Anion Transporting Polypeptide 1B1 Is Important for Protein Surface Expression

    Directory of Open Access Journals (Sweden)

    Jennina Taylor-Wells

    2014-01-01

    Full Text Available The organic anion transporting polypeptides (OATPs encompass a family of membrane transport proteins responsible for the uptake of xenobiotic compounds. Human organic anion transporting polypeptide 1B1 (OATP1B1 mediates the uptake of clinically relevant compounds such as statins and chemotherapeutic agents into hepatocytes, playing an important role in drug delivery and detoxification. The OATPs have a putative 12-transmembrane domain topology and a highly conserved signature sequence (human OATP1B1: DSRWVGAWWLNFL, spanning the extracellular loop 3/TM6 boundary. The presence of three conserved tryptophan residues at the TM interface suggests a structural role for the sequence. This was investigated by site-directed mutagenesis of selected amino acids within the sequence D251E, W254F, W258/259F, and N261A. Transport was measured using the substrate estrone-3-sulfate and surface expression detected by luminometry and confocal microscopy, facilitated by an extracellular FLAG epitope. Uptake of estrone-3-sulfate and the surface expression of D251E, W254F, and W258/259F were both significantly reduced from the wild type OATP1B1-FLAG in transfected HEK293T cells. Confocal microscopy revealed that protein was produced but was retained intracellularly. The uptake and expression of N261A were not significantly different. The reduction in surface expression and intracellular protein retention indicates a structural and/or membrane localization role for these signature sequence residues in the human drug transporter OATP1B1.

  8. The Signature Sequence Region of the Human Drug Transporter Organic Anion Transporting Polypeptide 1B1 Is Important for Protein Surface Expression.

    Science.gov (United States)

    Taylor-Wells, Jennina; Meredith, David

    2014-01-01

    The organic anion transporting polypeptides (OATPs) encompass a family of membrane transport proteins responsible for the uptake of xenobiotic compounds. Human organic anion transporting polypeptide 1B1 (OATP1B1) mediates the uptake of clinically relevant compounds such as statins and chemotherapeutic agents into hepatocytes, playing an important role in drug delivery and detoxification. The OATPs have a putative 12-transmembrane domain topology and a highly conserved signature sequence (human OATP1B1: DSRWVGAWWLNFL), spanning the extracellular loop 3/TM6 boundary. The presence of three conserved tryptophan residues at the TM interface suggests a structural role for the sequence. This was investigated by site-directed mutagenesis of selected amino acids within the sequence D251E, W254F, W258/259F, and N261A. Transport was measured using the substrate estrone-3-sulfate and surface expression detected by luminometry and confocal microscopy, facilitated by an extracellular FLAG epitope. Uptake of estrone-3-sulfate and the surface expression of D251E, W254F, and W258/259F were both significantly reduced from the wild type OATP1B1-FLAG in transfected HEK293T cells. Confocal microscopy revealed that protein was produced but was retained intracellularly. The uptake and expression of N261A were not significantly different. The reduction in surface expression and intracellular protein retention indicates a structural and/or membrane localization role for these signature sequence residues in the human drug transporter OATP1B1.

  9. CERTIFICATELESS SIGNATURE AND BLIND SIGNATURE

    Institute of Scientific and Technical Information of China (English)

    Zhang Lei; Zhang Futai

    2008-01-01

    Certificateless public key cryptography is a new paradigm introduced by AI-Riyami and Paterson. It eliminates the need of the certificates in traditional public key cryptosystems and the key escrow problem in IDentity-based Public Key Cryptography (ID-PKC). Due to the advantages of the certificateless public key cryptography,a new efficient certificateless pairing-based signature scheme is presented,which has some advantages over previous constructions in computational cost. Based on this new signature scheme,a certificateless blind signature scheme is proposed. The security of our schemes is proven based on the hardness of computational Diffie-Hellman problem.

  10. Effect of high energy proton irradiation on InAs/GaAs quantum dots: Enhancement of photoluminescence efficiency (up to {approx}7 times) with minimum spectral signature shift

    Energy Technology Data Exchange (ETDEWEB)

    Sreekumar, R.; Mandal, A. [Centre for Nanoelectronics, Department of Electrical Engineering, Indian Institute of Technology Bombay, Mumbai 400076, Maharashtra (India); Gupta, S.K. [Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai 400085, Maharashtra (India); Chakrabarti, S., E-mail: subho@ee.iitb.ac.in [Centre for Nanoelectronics, Department of Electrical Engineering, Indian Institute of Technology Bombay, Mumbai 400076, Maharashtra (India)

    2011-11-15

    Graphical abstract: Authors demonstrate enhancement in photoluminescence efficiency (7 times) in single layer InAs/GaAs quantum dots using proton irradiation without any post-annealing treatment via either varying proton energy (a) or fluence (b). The increase in PL efficiency is explained by a proposed model before (c) and after irradiation (d). Highlights: {yields} Proton irradiation improved PL efficiency in InAs/GaAs quantum dots (QDs). {yields} Proton irradiation favoured defect and strain annihilation in InAs/GaAs QDs. {yields} Reduction in defects/non-radiative recombination improved PL efficiency. {yields} Protons could be used to improve PL efficiency without spectral shift. {yields} QD based devices will be benefited by this technique to improve device performance. -- Abstract: We demonstrate 7-fold increase of photoluminescence efficiency in GaAs/(InAs/GaAs) quantum dot hetero-structure, employing high energy proton irradiation, without any post-annealing treatment. Protons of energy 3-5 MeV with fluence in the range (1.2-7.04) x 10{sup 12} ions/cm{sup 2} were used for irradiation. X-ray diffraction analysis revealed crystalline quality of the GaAs cap layer improves on proton irradiation. Photoluminescence study conducted at low temperature and low laser excitation density proved the presence of non-radiative recombination centers in the system which gets eliminated on proton irradiation. Shift in photoluminescence emission towards higher wavelength upon irradiation substantiated the reduction in strain field existed between GaAs cap layer and InAs/GaAs quantum dots. The enhancement in PL efficiency is thus attributed to the annihilation of defects/non-radiative recombination centers present in GaAs cap layer as well as in InAs/GaAs quantum dots induced by proton irradiation.

  11. Spectral analysis of atmospheric composition: application to surface ozone model-measurement comparisons

    Science.gov (United States)

    Bowdalo, Dene R.; Evans, Mathew J.; Sofen, Eric D.

    2016-07-01

    Models of atmospheric composition play an essential role in our scientific understanding of atmospheric processes and in providing policy strategies to deal with societally relevant problems such as climate change, air quality, and ecosystem degradation. The fidelity of these models needs to be assessed against observations to ensure that errors in model formulations are found and that model limitations are understood. A range of approaches are necessary for these comparisons. Here, we apply a spectral analysis methodology for this comparison. We use the Lomb-Scargle periodogram, a method similar to a Fourier transform, but better suited to deal with the gapped data sets typical of observational data. We apply this methodology to long-term hourly ozone observations and the equivalent model (GEOS-Chem) output. We show that the spectrally transformed observational data show a distinct power spectrum with regimes indicative of meteorological processes (weather, macroweather) and specific peaks observed at the daily and annual timescales together with corresponding harmonic peaks at one-half, one-third, etc., of these frequencies. Model output shows corresponding features. A comparison between the amplitude and phase of these peaks introduces a new comparison methodology between model and measurements. We focus on the amplitude and phase of diurnal and seasonal cycles and present observational/model comparisons and discuss model performance. We find large biases notably for the seasonal cycle in the mid-latitude Northern Hemisphere where the amplitudes are generally overestimated by up to 16 ppbv, and phases are too late on the order of 1-5 months. This spectral methodology can be applied to a range of model-measurement applications and is highly suitable for Multimodel Intercomparison Projects (MIPs).

  12. Adaption of the MODIS aerosol retrieval algorithm using airborne spectral surface reflectance measurements over urban areas: a case study

    Science.gov (United States)

    Jäkel, E.; Mey, B.; Levy, R.; Gu, X.; Yu, T.; Li, Z.; Althausen, D.; Heese, B.; Wendisch, M.

    2015-12-01

    MODIS (MOderate-resolution Imaging Spectroradiometer) retrievals of aerosol optical depth (AOD) are biased over urban areas, primarily because the reflectance characteristics of urban surfaces are different than that assumed by the retrieval algorithm. Specifically, the operational "dark-target" retrieval is tuned towards vegetated (dark) surfaces and assumes a spectral relationship to estimate the surface reflectance in blue and red wavelengths. From airborne measurements of surface reflectance over the city of Zhongshan, China, were collected that could replace the assumptions within the MODIS retrieval algorithm. The subsequent impact was tested upon two versions of the operational algorithm, Collections 5 and 6 (C5 and C6). AOD retrieval results of the operational and modified algorithms were compared for a specific case study over Zhongshan to show minor differences between them all. However, the Zhongshan-based spectral surface relationship was applied to a much larger urban sample, specifically to the MODIS data taken over Beijing between 2010 and 2014. These results were compared directly to ground-based AERONET (AErosol RObotic NETwork) measurements of AOD. A significant reduction of the differences between the AOD retrieved by the modified algorithms and AERONET was found, whereby the mean difference decreased from 0.27±0.14 for the operational C5 and 0.19±0.12 for the operational C6 to 0.10±0.15 and -0.02±0.17 by using the modified C5 and C6 retrievals. Since the modified algorithms assume a higher contribution by the surface to the total measured reflectance from MODIS, consequently the overestimation of AOD by the operational methods is reduced. Furthermore, the sensitivity of the MODIS AOD retrieval with respect to different surface types was investigated. Radiative transfer simulations were performed to model reflectances at top of atmosphere for predefined aerosol properties. The reflectance data were used as input for the retrieval methods. It

  13. 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.

  14. Effect of emissivity uncertainty on surface temperature retrieval over urban areas: Investigations based on spectral libraries

    NARCIS (Netherlands)

    Chen, F.; Yang, S.; Su, Zhongbo; Wang, K.

    2016-01-01

    Land surface emissivity (LSE) is a prerequisite for retrieving land surface temperature (LST) through single channel methods. According to error model, a 0.01 (1%) uncertainty of LSE may result in a 0.5 K error in LST under a moderate condition, while an obvious error (approximately 1 K) is possible

  15. Measuring and modeling the effect of surface moisture on the spectral reflectance of coastal beach sand

    NARCIS (Netherlands)

    Nolet, Corjan; Poortinga, Ate; Roosjen, Peter; Bartholomeus, Harm; Ruessink, Gerben

    2014-01-01

    Surface moisture is an important supply limiting factor for aeolian sand transport, which is the primary driver of coastal dune development. As such, it is critical to account for the control of surface moisture on available sand for dune building. Optical remote sensing has the potential to measure

  16. Infrared Spectral Observations While Drilling into a Frozen Lunar Simulant

    Science.gov (United States)

    Roush, Ted L.; Colaprete, Anthony; Thompson, Sarah; Cook, Amanda; Kleinhenz, Julie

    2014-01-01

    Past and continuing observations indicate an enrichment of volatile materials in lunar polar regions. While these volatiles may be located near the surface, access to them will likely require subsurface sampling, during which it is desirable to monitor the volatile content. In a simulation of such activities, a multilayer lunar simulant was prepared with differing water content, and placed inside a thermal vacuum chamber at Glenn Research Center (GRC). The soil profile was cooled using liquid nitrogen. In addition to the soil, a drill and infrared (IR) spectrometer (1600-3400 nm) were also located in the GRC chamber. We report the spectral observations obtained during a sequence where the drill was repeatedly inserted and extracted, to different depths, at the same location. We observe an overall increase in the spectral signature of water ice over the duration of the test. Additionally, we observe variations in the water ice spectral signature as the drill encounters different layers.

  17. Retrieval of Areal-averaged Spectral Surface Albedo from Transmission Data Alone: Computationally Simple and Fast Approach

    Energy Technology Data Exchange (ETDEWEB)

    Kassianov, Evgueni I.; Barnard, James C.; Flynn, Connor J.; Riihimaki, Laura D.; Michalsky, Joseph; Hodges, G. B.

    2014-10-25

    We introduce and evaluate a simple retrieval of areal-averaged surface albedo using ground-based measurements of atmospheric transmission alone at five wavelengths (415, 500, 615, 673 and 870nm), under fully overcast conditions. Our retrieval is based on a one-line semi-analytical equation and widely accepted assumptions regarding the weak spectral dependence of cloud optical properties, such as cloud optical depth and asymmetry parameter, in the visible and near-infrared spectral range. To illustrate the performance of our retrieval, we use as input measurements of spectral atmospheric transmission from Multi-Filter Rotating Shadowband Radiometer (MFRSR). These MFRSR data are collected at two well-established continental sites in the United States supported by the U.S. Department of Energy’s (DOE’s) Atmospheric Radiation Measurement (ARM) Program and National Oceanic and Atmospheric Administration (NOAA). The areal-averaged albedos obtained from the MFRSR are compared with collocated and coincident Moderate Resolution Imaging Spectroradiometer (MODIS) white-sky albedo. In particular, these comparisons are made at four MFRSR wavelengths (500, 615, 673 and 870nm) and for four seasons (winter, spring, summer and fall) at the ARM site using multi-year (2008-2013) MFRSR and MODIS data. Good agreement, on average, for these wavelengths results in small values (≤0.01) of the corresponding root mean square errors (RMSEs) for these two sites. The obtained RMSEs are comparable with those obtained previously for the shortwave albedos (MODIS-derived versus tower-measured) for these sites during growing seasons. We also demonstrate good agreement between tower-based daily-averaged surface albedos measured for “nearby” overcast and non-overcast days. Thus, our retrieval originally developed for overcast conditions likely can be extended for non-overcast days by interpolating between overcast retrievals.

  18. Spectral Dependent Degradation of the Solar Diffuser on Suomi-NPP VIIRS Due to Surface Roughness-Induced Rayleigh Scattering

    Directory of Open Access Journals (Sweden)

    Xi Shao

    2016-03-01

    Full Text Available The Visible Infrared Imaging Radiometer Suite (VIIRS onboard Suomi National Polar Orbiting Partnership (SNPP uses a solar diffuser (SD as its radiometric calibrator for the reflective solar band calibration. The SD is made of Spectralon™ (one type of fluoropolymer and was chosen because of its controlled reflectance in the Visible/Near-Infrared/Shortwave-Infrared region and its near-Lambertian reflectance property. On-orbit changes in VIIRS SD reflectance as monitored by the Solar Diffuser Stability Monitor showed faster degradation of SD reflectance for 0.4 to 0.6 µm channels than the longer wavelength channels. Analysis of VIIRS SD reflectance data show that the spectral dependent degradation of SD reflectance in short wavelength can be explained with a SD Surface Roughness (length scale << wavelength based Rayleigh Scattering (SRRS model due to exposure to solar UV radiation and energetic particles. The characteristic length parameter of the SD surface roughness is derived from the long term reflectance data of the VIIRS SD and it changes at approximately the tens of nanometers level over the operational period of VIIRS. This estimated roughness length scale is consistent with the experimental result from radiation exposure of a fluoropolymer sample and validates the applicability of the Rayleigh scattering-based model. The model is also applicable to explaining the spectral dependent degradation of the SDs on other satellites. This novel approach allows us to better understand the physical processes of the SD degradation, and is complementary to previous mathematics based models.

  19. Mapping Chemical and Structural Composition of Pharmaceutical and Biological Samples by Raman, Surface-Enhanced Raman and Fluorescence Spectral Imaging

    Science.gov (United States)

    Chourpa, Igor; Cohen-Jonathan, Simone; Dubois, Pierre

    Raman spectroscopy is an analytical technique recognised for its structural and conformational specificity. The efficient discrimination of molecular species by Raman is particularly potent for multidimensional microscopic imaging of complex biological environment, as demonstrated in the present book. The commonly admitted problem of Raman, low sensitivity, can often be circumvented due to high output instruments and via approaches like RRS (resonance Raman scattering), SERS (surface-enhanced Raman scattering), TERS (tip-enhanced Raman scattering) or CARS (coherent anti-Stokes Raman scattering). In contrast to the latter, RRS and SERS are realizable with less sophisticated set-up based on common Raman systems. Although more invasive than RRS, SERS provides better sensitivity and quenching of fluorescence. SERRS (surface-enhanced resonance Raman scattering) spectroscopy can be used in coupling with fluorescence and competes in selectivity and sensitivity with spectrofluorimetry. In the chapter below, we use recent applications made in our group to illustrate the use of Raman and SERRS spectral imaging for characterization of biological samples (animal subcutaneous tissue, human cancer cells) and pharmaceutical samples (microparticles for drug delivery, fibres for wound dressing). After a brief description of experimental details on spectral imaging, the chapter will focus on results concerning (i) biocompatible pharmaceutical materials made of alginates and (ii) anticancer drugs in pharmaceutical forms and in biological systems.

  20. Modeling and Predicting the Effect of Surface Oxidation on the Normal Spectral Emissivity of Aluminum 5052 at 800 K to 910 K

    Science.gov (United States)

    Shi, Deheng; Zou, Fenghui; Zhu, Zunlue; Sun, Jinfeng

    2016-01-01

    In this study, we tried to develop a model to predict the effect of surface oxidization on the normal spectral emissivity of aluminum 5052 at a temperature range of 800 to 910 K and wavelength of 1.5 \\upmu m. In experiments, specimens were heated in air for 6 h at certain temperatures. Two platinum-rhodium thermocouples were symmetrically welded onto the front surface of the specimens near the measuring area for accurate monitoring of the temperature at the specimen surface. The temperatures measured by the two thermocouples had an uncertainty of 1 K. The normal spectral emissivity values were measured over the 6-h heating period at temperatures from 800 K to 910 K in increments of 10 K. Strong oscillations in the normal spectral emissivity were observed at each temperature. These oscillations were determined to form by the interference between the radiation stemming from the oxide layer and radiation from the substrate. The present measurements were compared with previous experimental results, and the variation in the normal spectral emissivity at given temperatures was evaluated. The uncertainty of the normal spectral emissivity caused only by the surface oxidization was found to be approximately 12.1 % to 21.8 %, and the corresponding uncertainty in the temperature caused only by the surface oxidization was approximately 9.1 K to 15.2 K. The model can reproduce the normal spectral emissivity well, including the strong oscillations that occur during the initial heating period.

  1. Assessment of Surface Soil Moisture Using High-Resolution Multi-Spectral Imagery and Artificial Neural Networks

    Directory of Open Access Journals (Sweden)

    Leila Hassan-Esfahani

    2015-03-01

    Full Text Available Many crop production management decisions can be informed using data from high-resolution aerial images that provide information about crop health as influenced by soil fertility and moisture. Surface soil moisture is a key component of soil water balance, which addresses water and energy exchanges at the surface/atmosphere interface; however, high-resolution remotely sensed data is rarely used to acquire soil moisture values. In this study, an artificial neural network (ANN model was developed to quantify the effectiveness of using spectral images to estimate surface soil moisture. The model produces acceptable estimations of surface soil moisture (root mean square error (RMSE = 2.0, mean absolute error (MAE = 1.8, coefficient of correlation (r = 0.88, coefficient of performance (e = 0.75 and coefficient of determination (R2 = 0.77 by combining field measurements with inexpensive and readily available remotely sensed inputs. The spatial data (visual spectrum, near infrared, infrared/thermal are produced by the AggieAir™ platform, which includes an unmanned aerial vehicle (UAV that enables users to gather aerial imagery at a low price and high spatial and temporal resolutions. This study reports the development of an ANN model that translates AggieAir™ imagery into estimates of surface soil moisture for a large field irrigated by a center pivot sprinkler system.

  2. Spectral luminescent properties of bacteriochlorin and aluminum phthalocyanine nanoparticles as hydroxyapatite implant surface coating

    Directory of Open Access Journals (Sweden)

    Yu. S. Maklygina

    2016-01-01

    Full Text Available The development and the spectral research of unique coating as crystalline nanoparticles of IR photosensitizers were performed for the creation of hydroxyapatite implants with photobactericidal properties. It has been proved that by the interaction of nanoparticles covering implant with the polar solvent, which simulates the interaction of the implant with the biocomponents in vivo (fast proliferating and with immunocompetent cells, photosensitizers nanoparticles change the spectroscopic properties, becoming fluorescent and phototoxic. Thus, the developed coating based on crystalline photosensitizer nanoparticles with studied specific properties should have antibacterial, anti-inflammatory effect by the photodynamic treatment in the near implant area. This research opens the prospect of the local prevention of inflammatory and autoimmune reactions in the area of implantation. The results of the study suggest a promising this technology in order to create implants with photobactericidal properties.

  3. Geochemistry of organic carbon and nitrogen in surface sediments of coastal Bohai Bay inferred from their ratios and stable isotopic signatures.

    Science.gov (United States)

    Gao, Xuelu; Yang, Yuwei; Wang, Chuanyuan

    2012-06-01

    Total organic carbon (TOC), total nitrogen (TN) and their δ(13)C and δ(15)N values were determined for 42 surface sediments from coastal Bohai Bay in order to determine the concentration and identify the source of organic matter. The sampling sites covered both the marine region of coastal Bohai Bay and the major rivers it connects with. More abundant TOC and TN in sediments from rivers than from the marine region reflect the situation that most of the terrestrial organic matter is deposited before it meets the sea. The spatial variation in δ(13)C and δ(15)N signatures implies that the input of organic matter from anthropogenic activities has a more significant influence on its distribution than that from natural processes. Taking the area as a whole, surface sediments in the marine region of coastal Bohai Bay are dominated by marine derived organic carbon, which on average accounts for 62±11% of TOC.

  4. Impact of Environmental Factors on the Spectral Characteristics of Lava Surfaces: Field Spectrometry of Basaltic Lava Flows on Tenerife, Canary Islands, Spain

    Directory of Open Access Journals (Sweden)

    Long Li

    2015-12-01

    Full Text Available We report on spectral reflectance measurements of basaltic lava flows on Tenerife Island, Spain. Lava flow surfaces of different ages, surface roughness and elevations were systematically measured using a field spectroradiometer operating in the range of 350–2500 nm. Surface roughness, oxidation and lichen coverage were documented at each measured site. Spectral properties vary with age and morphology of lava. Pre-historical lavas with no biological coverage show a prominent increase in spectral reflectance in the 400–760 nm range and a decrease in the 2140–2210 nm range. Pāhoehoe surfaces have higher reflectance values than ʻaʻā ones and attain a maximum reflectance at wavelengths < 760 nm. Lichen-covered lavas are characterized by multiple lichen-related absorption and reflection features. We demonstrate that oxidation and lichen growth are two major factors controlling spectra of Tenerife lava surfaces and, therefore, propose an oxidation index and a lichen index to quantify surface alterations of lava flows: (1 the oxidation index is based on the increase of the slope of the spectral profile from blue to red as the field-observed oxidation level strengthens; and (2 the lichen index is based on the spectral reflectance in the 1660–1725 nm range, which proves to be highly correlated with lichen coverage documented in the field. The two spectral indices are applied to Landsat ETM+ and Hyperion imagery of the study area for mapping oxidation and lichen coverage on lava surfaces, respectively. Hyperion is shown to be capable of discriminating different volcanic surfaces, i.e., tephra vs. lava and oxidized lava vs. lichen-covered lava. Our study highlights the value of field spectroscopic measurements to aid interpretation of lava flow characterization using satellite images and of the effects of environmental factors on lava surface evolution over time, and, therefore, has the potential to contribute to the mapping as well as dating

  5. Surface temperature measurement of the plasma facing components with the multi-spectral infrared thermography diagnostics in tokamaks

    Science.gov (United States)

    Zhang, C.; Gauthier, E.; Pocheau, C.; Balorin, C.; Pascal, J. Y.; Jouve, M.; Aumeunier, M. H.; Courtois, X.; Loarer, Th.; Houry, M.

    2017-03-01

    For the long-pulse high-confinement discharges in tokamaks, the equilibrium of plasma requires a contact with the first wall materials. The heat flux resulting from this interaction is of the order of 10 MW/m2 for steady state conditions and up to 20 MW/m2 for transient phases. The monitoring on surface temperatures of the plasma facing components (PFCs) is a major concern to ensure safe operation and to optimize performances of experimental operations on large fusion facilities. Furthermore, this measurement is also required to study the physics associated to the plasma material interactions and the heat flux deposition process. In tokamaks, infrared (IR) thermography systems are routinely used to monitor the surface temperature of the PFCs. This measurement requires an accurate knowledge of the surface emissivity. However, and particularly for metallic materials such as tungsten, this emissivity value can vary over a wide range with both the surface condition and the temperature itself, which makes instantaneous measurement challenging. In this context, the multi-spectral infrared method appears as a very promising alternative solution. Indeed, the system has the advantage to carry out a non-intrusive measurement on thermal radiation while evaluating surface temperature without requiring a mandatory surface emissivity measurement. In this paper, a conceptual design for the multi-spectral infrared thermography is proposed. The numerical study of the multi-channel system based on the Levenberg-Marquardt (LM) nonlinear curve fitting is applied. The numerical results presented in this paper demonstrate the design allows for measurements over a large temperature range with a relative error of less than 10%. Furthermore, laboratory experiments have been performed from 200 °C to 740 °C to confirm the feasibility for temperature measurements on stainless steel and tungsten. In these experiments, the unfolding results from the multi-channel detection provide good

  6. Combined retrieval of Arctic liquid water cloud and surface snow properties using airborne spectral solar remote sensing

    Science.gov (United States)

    Ehrlich, André; Bierwirth, Eike; Istomina, Larysa; Wendisch, Manfred

    2017-09-01

    The passive solar remote sensing of cloud properties over highly reflecting ground is challenging, mostly due to the low contrast between the cloud reflectivity and that of the underlying surfaces (sea ice and snow). Uncertainties in the retrieved cloud optical thickness τ and cloud droplet effective radius reff, C may arise from uncertainties in the assumed spectral surface albedo, which is mainly determined by the generally unknown effective snow grain size reff, S. Therefore, in a first step the effects of the assumed snow grain size are systematically quantified for the conventional bispectral retrieval technique of τ and reff, C for liquid water clouds. In general, the impact of uncertainties of reff, S is largest for small snow grain sizes. While the uncertainties of retrieved τ are independent of the cloud optical thickness and solar zenith angle, the bias of retrieved reff, C increases for optically thin clouds and high Sun. The largest deviations between the retrieved and true original values are found with 83 % for τ and 62 % for reff, C. In the second part of the paper a retrieval method is presented that simultaneously derives all three parameters (τ, reff, C, reff, S) and therefore accounts for changes in the snow grain size. Ratios of spectral cloud reflectivity measurements at the three wavelengths λ1 = 1040 nm (sensitive to reff, S), λ2 = 1650 nm (sensitive to τ), and λ3 = 2100 nm (sensitive to reff, C) are combined in a trispectral retrieval algorithm. In a feasibility study, spectral cloud reflectivity measurements collected by the Spectral Modular Airborne Radiation measurement sysTem (SMART) during the research campaign Vertical Distribution of Ice in Arctic Mixed-Phase Clouds (VERDI, April/May 2012) were used to test the retrieval procedure. Two cases of observations above the Canadian Beaufort Sea, one with dense snow-covered sea ice and another with a distinct snow-covered sea ice edge are analysed. The retrieved values of τ, reff

  7. Combined retrieval of Arctic liquid water cloud and surface snow properties using airborne spectral solar remote sensing

    Directory of Open Access Journals (Sweden)

    A. Ehrlich

    2017-09-01

    Full Text Available The passive solar remote sensing of cloud properties over highly reflecting ground is challenging, mostly due to the low contrast between the cloud reflectivity and that of the underlying surfaces (sea ice and snow. Uncertainties in the retrieved cloud optical thickness τ and cloud droplet effective radius reff, C may arise from uncertainties in the assumed spectral surface albedo, which is mainly determined by the generally unknown effective snow grain size reff, S. Therefore, in a first step the effects of the assumed snow grain size are systematically quantified for the conventional bispectral retrieval technique of τ and reff, C for liquid water clouds. In general, the impact of uncertainties of reff, S is largest for small snow grain sizes. While the uncertainties of retrieved τ are independent of the cloud optical thickness and solar zenith angle, the bias of retrieved reff, C increases for optically thin clouds and high Sun. The largest deviations between the retrieved and true original values are found with 83 % for τ and 62 % for reff, C.In the second part of the paper a retrieval method is presented that simultaneously derives all three parameters (τ, reff, C, reff, S and therefore accounts for changes in the snow grain size. Ratios of spectral cloud reflectivity measurements at the three wavelengths λ1 = 1040 nm (sensitive to reff, S, λ2 = 1650 nm (sensitive to τ, and λ3 = 2100 nm (sensitive to reff, C are combined in a trispectral retrieval algorithm. In a feasibility study, spectral cloud reflectivity measurements collected by the Spectral Modular Airborne Radiation measurement sysTem (SMART during the research campaign Vertical Distribution of Ice in Arctic Mixed-Phase Clouds (VERDI, April/May 2012 were used to test the retrieval procedure. Two cases of observations above the Canadian Beaufort Sea, one with dense snow-covered sea ice and another with a distinct snow-covered sea ice

  8. Red-Edge Spectral Reflectance as an Indicator of Surface Moisture Content in an Alaskan Peatland Ecosystem

    Science.gov (United States)

    McPartland, M.; Kane, E. S.; Turetsky, M. R.; Douglass, T.; Falkowski, M. J.; Montgomery, R.; Edwards, J.

    2015-12-01

    Arctic and boreal peatlands serve as major reservoirs of terrestrial organic carbon (C) because Net Primary Productivity (NPP) outstrips C loss from decomposition over long periods of time. Peatland productivity varies as a function of water table position and surface moisture content, making C storage in these systems particularly vulnerable to the climate warming and drying predicted for high latitudes. Detailed spatial knowledge of how aboveground vegetation communities respond to changes in hydrology would allow for ecosystem response to environmental change to be measured at the landscape scale. This study leverages remotely sensed data along with field measurements taken at the Alaska Peatland Experiment (APEX) at the Bonanza Creek Long Term Ecological Research site to examine relationships between plant solar reflectance and surface moisture. APEX is a decade-long experiment investigating the effects of hydrologic change on peatland ecosystems using water table manipulation treatments (raised, lowered, and control). Water table levels were manipulated throughout the 2015 growing season, resulting in a maximum separation of 35 cm between raised and lowered treatment plots. Water table position, soil moisture content, depth to seasonal ice, soil temperature, photosynthetically active radiation (PAR), CO2 and CH4 fluxes were measured as predictors of C loss through decomposition and NPP. Vegetation was surveyed for percent cover of plant functional types. Remote sensing data was collected during peak growing season, when the separation between treatment plots was at maximum difference. Imagery was acquired via a SenseFly eBee airborne platform equipped with a Canon S110 red-edge camera capable of detecting spectral reflectance from plant tissue at 715 nm band center to within centimeters of spatial resolution. Here, we investigate empirical relationships between spectral reflectance, water table position, and surface moisture in relation to peat carbon balance.

  9. Real-time surface tracking system using common-path spectral domain optical coherence tomography

    Science.gov (United States)

    Kim, Keo-Sik; Park, Hyoung-Jun; Kang, Hyun Seo; Kang, Jin U.; Song, Chul-Gyu

    2012-11-01

    An enhanced surface tracking system based on optical coherence tomography (OCT) modality has been developed and tested for use in a surgical guidance system. A surface detection algorithm based on a Savitzky-Golay filter of A-scan data and thresholding was applied to real-time depth tracking. The algorithm output controlled a motorized stage to adjust the probe position according to the sample's topological variance in real-time. As a result, the root mean square error (RMSE: 4.2 μm) of our algorithm was relatively lower than the conventional method (RMSE: 16.6 μm). Also, OCT images obtained using the algorithm showed a significantly extended imaging range and active surface tracking in real time. Consequently, the devised method demonstrated potential for use in systems for guiding surgical robots and endoscopic OCT.

  10. Detection of small surface vessels in near, medium, and far infrared spectral bands

    Science.gov (United States)

    Dulski, R.; Milewski, S.; Kastek, M.; Trzaskawka, P.; Szustakowski, M.; Ciurapinski, W.; Zyczkowski, M.

    2011-11-01

    Protection of naval bases and harbors requires close co-operation between security and access control systems covering land areas and those monitoring sea approach routes. The typical location of naval bases and harbors - usually next to a large city - makes it difficult to detect and identify a threat in the dense regular traffic of various sea vessels (i.e. merchant ships, fishing boats, tourist ships). Due to the properties of vessel control systems, such as AIS (Automatic Identification System), and the effectiveness of radar and optoelectronic systems against different targets it seems that fast motor boats called RIB (Rigid Inflatable Boat) could be the most serious threat to ships and harbor infrastructure. In the paper the process and conditions for the detection and identification of high-speed boats in the areas of ports and naval bases in the near, medium and far infrared is presented. Based on the results of measurements and recorded thermal images the actual temperature contrast delta T (RIB / sea) will be determined, which will further allow to specify the theoretical ranges of detection and identification of the RIB-type targets for an operating security system. The data will also help to determine the possible advantages of image fusion where the component images are taken in different spectral ranges. This will increase the probability of identifying the object by the multi-sensor security system equipped additionally with the appropriate algorithms for detecting, tracking and performing the fusion of images from the visible and infrared cameras.

  11. Free-surface Multiples and full-waveform inversion spectral resolution

    NARCIS (Netherlands)

    Kazei, V.V.; Kashtan, B.M.; Troyan, V.N.; Mulder, W.A.

    2015-01-01

    Low frequencies play a crucial role in the convergence of full-waveform inversion to the correct model in most of its current implementations. However, the lower the frequencies, the bigger are the amplitudes of the surface waves, causing the inversion to be driven by the latter. If they are not bla

  12. High-conductivity silicon based spectrally selective plasmonic surfaces for sensing in the infrared region

    Science.gov (United States)

    Gorgulu, K.; Gok, A.; Yilmaz, M.; Topalli, K.; Okyay, A. K.

    2017-02-01

    Plasmonic perfect absorbers have found a wide range of applications in imaging, sensing, and light harvesting and emitting devices. Traditionally, metals are used to implement plasmonic structures. For sensing applications, it is desirable to integrate nanophotonic active surfaces with biasing and amplification circuitry to achieve monolithic low cost solutions. Commonly used plasmonic metals such as Au and Ag are not compatible with standard silicon complementary metal-oxide-semiconductor (CMOS) technology. Here we demonstrate plasmonic perfect absorbers based on high conductivity silicon. Standard optical lithography and reactive ion etching techniques were used for the patterning of the samples. We present computational and experimental results of surface plasmon resonances excited on a silicon surface at normal and oblique incidences. We experimentally demonstrate our absorbers as ultra-low cost, CMOS-compatible and efficient refractive index sensing surfaces. The experimental results reveal that the structure exhibits a sensitivity of around 11 000 nm/RIU and a figure of merit of up to 2.5. We also show that the sensing performance of the structure can be improved by increasing doping density.

  13. Physical characterization, spectral response and remotely sensed mapping of Mediterranean soil surface crusts

    NARCIS (Netherlands)

    Jong, S.M. de; Addink, E.A.; Duijsing, D.; Beek, L.P.H. van

    2011-01-01

    Soil surface crusting and sealing are frequent but unfavorable processes in Mediterranean areas. Soil crust and seals form on bare soil subject to high-intensity rainfall, resulting in a hard, impenetrable layer that impedes infiltration and hampers the germination and establishment of plants. The a

  14. Comparison of the surface ion density of silica gel evaluated via spectral induced polarization versus acid-base titration

    Science.gov (United States)

    Hao, Na; Moysey, Stephen M. J.; Powell, Brian A.; Ntarlagiannis, Dimitrios

    2016-12-01

    Surface complexation models are widely used with batch adsorption experiments to characterize and predict surface geochemical processes in porous media. In contrast, the spectral induced polarization (SIP) method has recently been used to non-invasively monitor in situ subsurface chemical reactions in porous media, such as ion adsorption processes on mineral surfaces. Here we compare these tools for investigating surface site density changes during pH-dependent sodium adsorption on a silica gel. Continuous SIP measurements were conducted using a lab scale column packed with silica gel. A constant inflow of 0.05 M NaCl solution was introduced to the column while the influent pH was changed from 7.0 to 10.0 over the course of the experiment. The SIP measurements indicate that the pH change caused a 38.49 ± 0.30 μS cm- 1 increase in the imaginary conductivity of the silica gel. This increase is thought to result from deprotonation of silanol groups on the silica gel surface caused by the rise in pH, followed by sorption of Na+ cations. Fitting the SIP data using the mechanistic model of Leroy et al. (Leroyet al., 2008), which is based on the triple layer model of a mineral surface, we estimated an increase in the silica gel surface site density of 26.9 × 1016 sites m- 2. We independently used a potentiometric acid-base titration data for the silica gel to calibrate the triple layer model using the software FITEQL and observed a total increase in the surface site density for sodium sorption of 11.2 × 1016 sites m- 2, which is approximately 2.4 times smaller than the value estimated using the SIP model. By simulating the SIP response based on the calibrated surface complexation model, we found a moderate association between the measured and estimated imaginary conductivity (R2 = 0.65). These results suggest that the surface complexation model used here does not capture all mechanisms contributing to polarization of the silica gel captured by the SIP data.

  15. Martian Surface Temperature and Spectral Response from the MSL REMS Ground Temperature Sensor

    Science.gov (United States)

    Martin-Torres, Javier; Martínez-Frías, Jesús; Zorzano, María-Paz; Serrano, María; Mendaza, Teresa; Hamilton, Vicky; Sebastián, Eduardo; Armiens, Carlos; Gómez-Elvira, Javier; REMS Team

    2013-04-01

    The Rover Environmental Monitoring Station (REMS) on the Mars Science Laboratory (MSL) offers the opportunity to explore the near surface atmospheric conditions and, in particular will shed new light into the heat budget of the Martian surface. This is important for studies of the atmospheric boundary layer (ABL), as the ground and air temperatures measured directly by REMS control the coupling of the atmosphere with the surface [Zurek et al., 1992]. This coupling is driven by solar insolation. The ABL plays an important role in the general circulation and the local atmospheric dynamics of Mars. One of the REMS sensors, the ground temperature sensor (GTS), provides the data needed to study the thermal inertia properties of the regolith and rocks beneath the MSL rover. The GTS includes thermopile detectors, with infrared bands of 8-14 µm and 16-20 µm [Gómez-Elvira et al., 2012]. These sensors are clustered in a single location on the MSL mast and the 8-14 µm thermopile sounds the surface temperature. The infrared radiation reaching the thermopile is proportional to the emissivity of the surface minerals across these thermal wavelengths. We have developed a radiative transfer retrieval method for the REMS GTS using a database of thermal infrared laboratory spectra of analogue minerals and their mixtures. [Martín Redondo et al. 2009, Martínez-Frías et al. 2012 - FRISER-IRMIX database]. This method will be used to assess the perfomance of the REMS GTS as well as determine, through the error analysis, the surface temperature and emissivity values where MSL is operating. Comparisons with orbiter data will be performed. References Gómez-Elvira et al. [2012], REMS: The Environmental Sensor Suite for the Mars Science Laboratory Rover, Space Science Reviews, Volume 170, Issue 1-4, pp. 583-640. Martín-Redondo et al. [2009] Journal of Environmental Monitoring 11:, pp. 1428-1432. Martínez-Frías et al. [2012] FRISER-IRMIX database http

  16. The spectral emittance and stability of coatings and textured surfaces for thermophotovoltaic (TPV) radiator applications

    Energy Technology Data Exchange (ETDEWEB)

    Cockeram, B.V.; Hollenbeck, J.L.

    2000-11-01

    Coatings or surface modifications are needed to improve the surface emissivity of materials under consideration for TPV radiator applications to a value of 0.8 or higher. Vacuum plasma spray coatings (ZrO{sub 2} + 18% TiO{sub 2} + 10% Y{sub 2}O{sub 3}, ZrC, Fe{sub 2}TiO{sub 5}, ZrTiO{sub 4}, ZrO{sub 2} + 8% Y{sub 2}O{sub 3} + 2% HfO{sub 2}, and Al{sub 2}O{sub 3} + TiO{sub 2}) and a chemical vapor deposited coating of rhenium whiskers were used to increase the surface emissivity of refractory metal and nickel-base materials. Emittance measurements following 4000 hours of vacuum annealing at 1100 C show that only the ZrO{sub 2} + 18% TiO{sub 2} + 10% Y{sub 2}O{sub 3}, ZrC, and Al{sub 2}O{sub 3} + TiO{sub 2} coatings have the desired thermal stability, and maintain emissivity values higher than 0.8. These coatings are graybody emitters, and provide a high emissivity value in the wavelength range that is relevant to the TPV cells. The highest emissivity values were observed for the Al{sub 2}O{sub 3} + TiO{sub 2} coatings, with post-anneal values higher than graphite.

  17. Design concepts of monolithic metamorphic vertical-cavity surface-emitting lasers for the 1300–1550 nm spectral range

    Energy Technology Data Exchange (ETDEWEB)

    Egorov, A. Yu., E-mail: anton@beam.ioffe.ru; Karachinsky, L. Ya.; Novikov, I. I.; Babichev, A. V.; Nevedomskiy, V. N. [Russian Academy of Sciences, Ioffe Institute (Russian Federation); Bugrov, V. E. [ITMO University (Russian Federation)

    2015-11-15

    Possible design concepts for long-wavelength vertical-cavity surface-emitting lasers for the 1300–1550 nm spectral range on GaAs substrates are suggested. It is shown that a metamorphic GaAs–InGaAs heterostructure with a thin buffer layer providing rapid transition from the lattice constant of GaAs to that of In{sub x}Ga{sub 1–x}As with an indium fraction of x < 0.3 can be formed by molecular-beam epitaxy. Analysis by transmission electron microscopy demonstrated the effective localization of mismatch dislocations in the thin buffer layer and full suppression of their penetration into the overlying InGaAs metamorphic layer.

  18. Topographic power spectral density study of the effect of surface treatment processes on niobium for superconducting radio frequency accelerator cavities

    Energy Technology Data Exchange (ETDEWEB)

    Charles Reece, Hui Tian, Michael Kelley, Chen Xu

    2012-04-01

    Microroughness is viewed as a critical issue for attaining optimum performance of superconducting radio frequency accelerator cavities. The principal surface smoothing methods are buffered chemical polish (BCP) and electropolish (EP). The resulting topography is characterized by atomic force microscopy (AFM). The power spectral density (PSD) of AFM data provides a more thorough description of the topography than a single-value roughness measurement. In this work, one dimensional average PSD functions derived from topography of BCP and EP with different controlled starting conditions and durations have been fitted with a combination of power law, K correlation, and shifted Gaussian models to extract characteristic parameters at different spatial harmonic scales. While the simplest characterizations of these data are not new, the systematic tracking of scale-specific roughness as a function of processing is new and offers feedback for tighter process prescriptions more knowledgably targeted at beneficial niobium topography for superconducting radio frequency applications.

  19. Estimate of Small Stiffness and Damping Ratio in Residual Soil Using Spectral Analysis of Surface Wave Method

    Directory of Open Access Journals (Sweden)

    Bawadi Nor Faizah

    2016-01-01

    Full Text Available Research in the important parameters for modeling the dynamic behavior of soils has led to rapid development of the small strain stiffness and damping ratio for use in the seismic method. It is because, the experimental determination of the damping ratio is problematic, especially for hard soils sample. Many researchers have proved that the surface wave method is a reliable tool to determine shear wave velocity and damping ratio profiles at a site with very small strains level. Surface wave methods based on Rayleigh waves propagation and the resulting attenuation curve can become erroneous when higher modes contribute to the soil’s response. In this study, two approaches has been used to determine the shear strain amplitude and damping ratio of residual soils at small strain level using Spectral Analysis of Surface Wave (SASW method. One is to derive shear strain amplitude from the frequency-response curve and the other is to derive damping ratio from travel-time data. Then, the results are compared to the conventional method.

  20. Fast Inversion of Air-Coupled Spectral Analysis of Surface Wave (SASW Using in situ Particle Displacement

    Directory of Open Access Journals (Sweden)

    Yifeng Lu

    2015-11-01

    Full Text Available Spectral Analysis of Surface Wave (SASW is widely used in nondestructive subsurface profiling for geological sites. The air-coupled SASW is an extension from conventional SASW methods by replacing ground-mounted accelerometers with non-contact microphones, which acquire a leaky surface wave instead of ground vibration. The air-coupled SASW is a good candidate for fast inspection in shallow geological studies. Especially for pavement maintenance, minimum traffic interference might be induced. One issue that restrains SASW from fast inspection is the traditional slow inversion which relies on guess-and-check iteration techniques including a forward analysis. In this article, a fast inversion analysis algorithm is proposed to estimate the shear velocity profile without performing conventional forward simulation. By investigating the attenuation of particle displacement along penetrating depths, a weighted combination relationship is derived to connect the dispersion curve with the shear velocity profile directly. Using this relationship, the shear velocity profile could be estimated from a given/measured dispersion curve. The proposed procedure allows the surface wave-based method to be fully automatic and even operated in real-time for geological site and pavement assessment. The method is verified by the forward analysis with stiffness matrix method. It is also proved by comparing with other published results using various inversion methods.

  1. Integration of Field and Laboratory Spectral Data with Multi-Resolution Remote Sensed Imagery for Asphalt Surface Differentiation

    Directory of Open Access Journals (Sweden)

    Alessandro Mei

    2014-03-01

    Full Text Available The ability to classify asphalt surfaces is an important goal for the selection of suitable non-variant targets as pseudo-invariant targets during the calibration/validation of remotely-sensed images. In addition, the possibility to recognize different types of asphalt surfaces on the images can help optimize road network management. This paper presents a multi-resolution study to improve asphalt surface differentiation using field spectroradiometric data, laboratory analysis and remote sensing imagery. Multispectral Infrared and Visible Imaging Spectrometer (MIVIS airborne data and multispectral images, such as Quickbird and Ikonos, were used. From scatter plots obtained by field data using λ = 460 and 740 nm, referring to MIVIS Bands 2 and 16 and Quickbird and Ikonos Bands 1 and 4, pixels corresponding to asphalt covering were identified, and the slope of their interpolation lines, assumed as asphalt lines, was calculated. These slopes, used as threshold values in the Spectral Angle Mapper (SAM classifier, obtained an overall accuracy of 95% for Ikonos, 98% for Quickbird and 93% for MIVIS. Laboratory investigations confirm the existence of the asphalt line also for new asphalts, too.

  2. Classification of signature-only signature models

    Institute of Scientific and Technical Information of China (English)

    CAO ZhengJun; LIU MuLan

    2008-01-01

    We introduce a set of criterions for classifying signature-only signature models. By the criterions, we classify signature models into 5 basic types and 69 general classes. Theoretically, 21141 kinds of signature models can be derived by appro-priately combining different general classes. The result comprises almost existing signature models. It will be helpful for exploring new signature models. To the best of our knowledge, it is the first time for investigation of the problem of classifica-tion of signature-only signature models.

  3. Airborne Spectral BRDF of Various Surface Types (Ocean, Vegetation, Snow, Desert, Wetlands, Cloud Decks, Smoke Layers) for Remote Sensing Applications

    Science.gov (United States)

    Gatebe, Charles K.; King, Michael D.

    2016-01-01

    In this paper we describe measurements of the bidirectional reflectance-distribution function (BRDF) acquired over a 30-year period (1984-2014) by the National Aeronautics and Space Administration's (NASA's) Cloud Absorption Radiometer (CAR). Our BRDF database encompasses various natural surfaces that are representative of many land cover or ecosystem types found throughout the world. CAR's unique measurement geometry allows a comparison of measurements acquired from different satellite instruments with various geometrical configurations, none of which are capable of obtaining such a complete and nearly instantaneous BRDF. This database is therefore of great value in validating many satellite sensors and assessing corrections of reflectances for angular effects. These data can also be used to evaluate the ability of analytical models to reproduce the observed directional signatures, to develop BRDF models that are suitable for sub-kilometer-scale satellite observations over both homogeneous and heterogeneous landscape types, and to test future spaceborne sensors. All of these BRDF data are publicly available and accessible in hierarchical data format (http:car.gsfc.nasa.gov/).

  4. DEMON-type algorithms for determination of hydro-acoustic signatures of surface ships and of divers

    Science.gov (United States)

    Slamnoiu, G.; Radu, O.; Rosca, V.; Pascu, C.; Damian, R.; Surdu, G.; Curca, E.; Radulescu, A.

    2016-08-01

    With the project “System for detection, localization, tracking and identification of risk factors for strategic importance in littoral areas”, developed in the National Programme II, the members of the research consortium intend to develop a functional model for a hydroacoustic passive subsystem for determination of acoustic signatures of targets such as fast boats and autonomous divers. This paper presents some of the results obtained in the area of hydroacoustic signal processing by using DEMON-type algorithms (Detection of Envelope Modulation On Noise). For evaluation of the performance of various algorithm variations we have used both audio recordings of the underwater noise generated by ships and divers in real situations and also simulated noises. We have analysed the results of processing these signals using four DEMON algorithm structures as presented in the reference literature and a fifth DEMON algorithm structure proposed by the authors of this paper. The algorithm proposed by the authors generates similar results to those obtained by applying the traditional algorithms but requires less computing resources than those and at the same time it has proven to be more resilient to random noise influence.

  5. Science of Land Target Spectral Signatures

    Science.gov (United States)

    2013-04-03

    parametric th dme o s • Extreme Value Theory – Fisher-Tippett theorem is the “Central Limit Theorem” for tail distributions. – Can model both CFAR detector...assumption that the signal generation kinetics for polymer coated evanescent wave sensor systems is solely based on Fickian diffusion of the analyte...was published by Phillips et al [43] showing that also surrounding flow conditions of the sensor contribute significantly to the diffusion kinetics

  6. Surface Plasmon Enhanced Sensitive Detection for Possible Signature of Majorana Fermions via a Hybrid Semiconductor Quantum Dot-Metal Nanoparticle System.

    Science.gov (United States)

    Chen, Hua-Jun; Zhu, Ka-Di

    2015-08-27

    In the present work, we theoretically propose an optical scheme to detect the possible signature of Majorana fermions via the optical pump-probe spectroscopy, which is very different from the current tunneling measurement based on electrical methods. The scheme consists of a metal nanoparticle and a semiconductor quantum dot coupled to a hybrid semiconductor/superconductor heterostructures. The results show that the probe absorption spectrum of the quantum dot presents a distinct splitting due to the existence of Majorana fermions. Owing to surface plasmon enhanced effect, this splitting will be more obvious, which makes Majorana fermions more easy to be detectable. The technique proposed here open the door for new applications ranging from robust manipulation of Majorana fermions to quantum information processing based on Majorana fermions.

  7. Spectral gamma-ray signature of fluvial deposits: a case study from the Late Permian Rio do Rasto Formation, Parana Basin, Brazil; Assinatura gamaespectrometrica de depositos fluviais: estudo de caso na Formacao do Rio do Rasto, Permiano Superior da Bacia do Parana

    Energy Technology Data Exchange (ETDEWEB)

    Sowek, Guilherme Arruda, E-mail: arruda@ufpr.br [Universidade Federal do Parana (UFPR), Curitiba, PR (Brazil). Programa de Pos-graduacao em Geologia; Ferreira, Francisco Jose Fonseca; Vesely, Fernando Farias, E-mail: francisco.ferreira@ufpr.br, E-mail: vesely@ufpr.br [Universidade Federal do Parana (UFPR), Curitiba, PR (Brazil). Dept. de Geologia. Setor de Ciencias da Terra; Berton, Fabio, E-mail: fabioberton1@yahoo.com.br [Universidade Federal do Parana (UFPR), Curitiba, PR (Brazil)

    2013-09-15

    Fluvial channel-fill deposits form highly heterogeneous hydrocarbon reservoirs. The study of outcrop analogs can help in the characterization of these heterogeneities, which are usually not detected by subsurface geophysical methods. The aim of this research is to compare outcrop log signatures with grain size trends and depositional elements of the fluvial deposits of the Late Permian Rio do Rasto Formation. A series of vertical gamma-ray logs were assembled in two outcrops in order to: 1) characterize log-facies in a succession composed of alternated flood plain, channel fill and eolian strata; 2) define within-channel spectral gamma-ray variability of a mixed-load composite point bar deposit and its relationship with grain size trends and lithofacies; 3) correlate log signatures observed in the outcrop sections with deep exploratory wells drilled several tens of kilometers from the study area. The results of this study show that gamma-ray logs have good correlation with grain size trends and that different depositional elements have distinct signatures. On the other hand, point bar deposits exhibit strong lateral changes in log signature due variations in grain size and mud content within lateral accretion strata. Although frequent, the classic bell-shaped log motif was not always detected, which means that the amount of fluvial channel-fill deposits recognized in subsurface can be underestimated. Similar log signatures were detected in the boreholes, at least in the closest ones, helping in paleoenvironmental interpretation in the subsurface. (author)

  8. High-Resolution Mapping of Urban Surface Water Using ZY-3 Multi-Spectral Imagery

    Directory of Open Access Journals (Sweden)

    Fangfang Yao

    2015-09-01

    Full Text Available Accurate information of urban surface water is important for assessing the role it plays in urban ecosystem services under the content of urbanization and climate change. However, high-resolution monitoring of urban water bodies using remote sensing remains a challenge because of the limitation of previous water indices and the dark building shadow effect. To address this problem, we proposed an automated urban water extraction method (UWEM which combines a new water index, together with a building shadow detection method. Firstly, we trained the parameters of UWEM using ZY-3 imagery of Qingdao, China. Then we verified the algorithm using five other sub-scenes (Aksu, Fuzhou, Hanyang, Huangpo and Huainan ZY-3 imagery. The performance was compared with that of the Normalized Difference Water Index (NDWI. Results indicated that UWEM performed significantly better at the sub-scenes with kappa coefficients improved by 7.87%, 32.35%, 12.64%, 29.72%, 14.29%, respectively, and total omission and commission error reduced by 61.53%, 65.74%, 83.51%, 82.44%, and 74.40%, respectively. Furthermore, UWEM has more stable performances than NDWI’s in a range of thresholds near zero. It reduces the over- and under-estimation issues which often accompany previous water indices when mapping urban surface water under complex environmental conditions.

  9. A spectral invariant representation of spectral reflectance

    Science.gov (United States)

    Ibrahim, Abdelhameed; Tominaga, Shoji; Horiuchi, Takahiko

    2011-03-01

    Spectral image acquisition as well as color image is affected by several illumination factors such as shading, gloss, and specular highlight. Spectral invariant representations for these factors were proposed for the standard dichromatic reflection model of inhomogeneous dielectric materials. However, these representations are inadequate for other characteristic materials like metal. This paper proposes a more general spectral invariant representation for obtaining reliable spectral reflectance images. Our invariant representation is derived from the standard dichromatic reflection model for dielectric materials and the extended dichromatic reflection model for metals. We proof that the invariant formulas for spectral images of natural objects preserve spectral information and are invariant to highlights, shading, surface geometry, and illumination intensity. It is proved that the conventional spectral invariant technique can be applied to metals in addition to dielectric objects. Experimental results show that the proposed spectral invariant representation is effective for image segmentation.

  10. Infrared spectral investigations of UV irradiated nucleobases adsorbed on mineral surfaces

    Science.gov (United States)

    Fornaro, Teresa; Brucato, John Robert; Pace, Emanuele; Guidi, Mariangela Cestelli; Branciamore, Sergio; Pucci, Amaranta

    2013-09-01

    The interaction between electromagnetic radiation and bio-molecules in heterogeneous environments is a prebiotically relevant process. Minerals may have a pivotal role in the prebiotic evolution of complex chemical systems, mediating the effects of electromagnetic radiation, influencing the photostability of bio-molecules, catalyzing important chemical reactions and/or protecting molecules against degradation. In particular, nucleobases are relevant bio-molecules to investigate both in the prebiotic context, because they are coding components of nucleic acids, and from the standpoint of the survival of biological systems in space conditions. Several studies on the photodynamics of nucleobases suggest that their structure could have been naturally selected for the ability to dissipate electronic energy through ultrafast photophysical decay. Considering the putative involvement of minerals in the prebiotic chemistry, it is necessary to study the photostability of nucleobases under space conditions in the presence of mineral matrices, to investigate both the prebiotic processes that might have had a role in the development of the first living entities on Earth and the physical and chemical processes occurring in extraterrestrial environments. We focused our study on the characterization of the nature of the interaction between nucleobases and the surface of the minerals magnesium oxide and forsterite by infrared vibrational spectroscopy. We observed that most of the characteristic bands of pure nucleobases vanished when adsorbed on magnesium oxide. On the contrary, in the case of adenine and uracil adsorbed on forsterite, very intense nucleobase absorption peaks appeared. This phenomenon pertains to the surface selection rules changes related to molecular orientation. Moreover, based on the vibrational shifts, we deduced the molecular interaction sites with the mineral surfaces. Furthermore, we investigated the photostability of nucleobases adsorbed on such minerals

  11. Avoided Crossing Patterns and Spectral Gaps of Surface Plasmon Modes in Gold Nano-Structures

    CERN Document Server

    Kolomenskii, Alexandre; Hembd, Jeshurun; Kolomenski, Andrei; Noel, John; Teizer, Winfried; Schuessler, Hans

    2010-01-01

    The transmission of ultrashort (7 fs) broadband laser pulses through periodic gold nano-structures is studied. The distribution of the transmitted light intensity over wavelength and angle shows an efficient coupling of the incident p-polarized light to two counter-propagating surface plasmon (SP) modes. As a result of the mode interaction, the avoided crossing patterns exhibit energy and momentum gaps, which depend on the configuration of the nano-structure and the wavelength. Variations of the widths of the SP resonances and an abrupt change of the mode interaction in the vicinity of the avoided crossing region are observed. These features are explained by the model of two coupled modes and a coupling change due to switching from the high frequency dark mode to the low frequency bright mode for increasing wavelength of the excitation light. PACS numbers: 73.20.Mf, 42.70.Qs, 42.25.-p,

  12. Spectral analysis of the low energy Auger emission from a (0 0 0 1) ruthenium surface

    Energy Technology Data Exchange (ETDEWEB)

    Czyzewski, Jerzy J.; Krajniak, Janusz

    2003-04-30

    The low energy Auger emission from a Ru(0 0 0 1) surface have been analysed by means of a cylindrical mirror analyser (CMA) within the range of the electron energy (E) from 27 to 37 eV as a function of the primary electron energy (E{sub p}), which was set from 170 to 450 eV in 20 eV steps. Three Auger transitions at following energies: 31.7, 33.8 and 36.4 eV, have been found due to application of the backscattering generation factor idea. Obtained results for the Auger transitions were verified by means of XPS results published by Fuggle et al. [Surf. Sci. 52 (1975) 521].

  13. Processes controlling the surface temperature signature of the Madden–Julian Oscillation in the thermocline ridge of the Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Jayakumar, A.; Vialard, J.; Lengaigne, M.; Gnanaseelan, C.; McCreary, J.P.; PraveenKumar, B.

    During boreal winter, there is a prominent maximum of intraseasonal sea-surface temperature (SST) variability associated with the Madden–Julian Oscillation (MJO) along a Thermocline Ridge located in the southwestern Indian Ocean (5 degrees S–10...

  14. Signature of a three-dimensional photonic band gap observed on silicon inverse woodpile photonic crystals

    CERN Document Server

    Huisman, Simon R; Woldering, Léon A; Leistikow, Merel D; Mosk, Allard P; Vos, Willem L

    2010-01-01

    We have studied the reflectivity of CMOS-compatible three-dimensional silicon inverse woodpile photonic crystals at near-infrared frequencies. Polarization-resolved reflectivity spectra were obtained from two orthogonal crystal surfaces corresponding to 1.88 pi sr solid angle. The spectra reveal broad peaks with high reflectivity up to 67 % that are independent of the spatial position on the crystals. The spectrally overlapping reflectivity peaks for all directions and polarizations form the signature of a broad photonic band gap with a relative bandwidth up to 16 %. This signature is supported with stopgaps in plane wave bandstructure calculations and with the frequency region of the expected band gap.

  15. Surface spectral function of momentum-dependent pairing potentials in a topological insulator: application to CuxBi2Se3.

    Science.gov (United States)

    Chen, Liang; Wan, Shaolong

    2013-05-29

    We propose three possible momentum-dependent pairing potentials as candidates for topological superconductors (for example CuxBi2Se3), and calculate the surface spectral function and surface density of states with these pairing potentials. We find that the first two can give the same spectral functions as the fully gapped and node-contacted pairing potentials given by Fu and Berg (2010 Phys. Rev. Lett. 105 097001), and that the third one can obtain a topological non-trivial case in which there exists a flat Andreev bound state and which preserves the threefold rotation symmetry. We hope our proposals and results will be assessed by future experiment.

  16. Urban Surface Temperature Time Series Estimation at the Local Scale by Spatial-Spectral Unmixing of Satellite Observations

    Directory of Open Access Journals (Sweden)

    Zina Mitraka

    2015-04-01

    Full Text Available The study of urban climate requires frequent and accurate monitoring of land surface temperature (LST, at the local scale. Since currently, no space-borne sensor provides frequent thermal infrared imagery at high spatial resolution, the scientific community has focused on synergistic methods for retrieving LST that can be suitable for urban studies. Synergistic methods that combine the spatial structure of visible and near-infrared observations with the more frequent, but low-resolution surface temperature patterns derived by thermal infrared imagery provide excellent means for obtaining frequent LST estimates at the local scale in cities. In this study, a new approach based on spatial-spectral unmixing techniques was developed for improving the spatial resolution of thermal infrared observations and the subsequent LST estimation. The method was applied to an urban area in Crete, Greece, for the time period of one year. The results were evaluated against independent high-resolution LST datasets and found to be very promising, with RMSE less than 2 K in all cases. The developed approach has therefore a high potential to be operationally used in the near future, exploiting the Copernicus Sentinel (2 and 3 observations, to provide high spatio-temporal resolution LST estimates in cities.

  17. Electron dynamics in the normal state of cuprates: Spectral function, Fermi surface and ARPES data

    Science.gov (United States)

    Zubov, E. E.

    2016-11-01

    An influence of the electron-phonon interaction on excitation spectrum and damping in a narrow band electron subsystem of cuprates has been investigated. Within the framework of the t-J model an approach to solving a problem of account of both strong electron correlations and local electron-phonon binding with characteristic Einstein mode ω0 in the normal state has been presented. In approximation Hubbard-I it was found an exact solution for the polaron bands. We established that in the low-dimensional system with a pure kinematic part of Hamiltonian a complicated excitation spectrum is realized. It is determined mainly by peculiarities of the lattice Green's function. In the definite area of the electron concentration and hopping integrals a correlation gap may be possible on the Fermi level. Also, in specific cases it is observed a doping evolution of the Fermi surface. We found that the strong electron-phonon binding enforces a degree of coherence of electron-polaron excitations near the Fermi level and spectrum along the nodal direction depends on wave vector module weakly. It corresponds to ARPES data. A possible origin of the experimentally observed kink in the nodal direction of cuprates is explained by fine structure of the polaron band to be formed near the mode -ω0.

  18. Metabolic Signatures of Oxidative Stress and Their Relationship with Erythrocyte Membrane Surface Roughness Among Workers of Manual Materials Handling (MMH).

    Science.gov (United States)

    Ghosh, Subrata; Acharyya, Muktish; Majumder, Titlee; Bagchi, Anandi

    2015-12-01

    Brickfield workers in India perform manual materials handling (MMH) and as a result, are at a high risk of developing oxidative stress. This results in an alteration of the various markers of metabolic oxidative stress at the cellular level. Since red blood cell (RBC) is the central point where oxygen, glucose-6-phosphate dehydrogenase (G-6-PD), and glutathione (GSH) are involved, the surface roughness and its alteration and modeling with respect to workers exposed to MMH may be considered as helpful determinants in predicting early damage to the cell and restoring better health to the exposed population, that is, the worker exposed to stress. Hence, nanometric analysis of the surface roughness of the RBC may serve as an early indicator of the stress-related damage in these individuals. The purpose of the study was to identify early red blood corpuscular surface damage profile in terms of linear modeling correlating various biochemical parameters. Linear modeling has been aimed to be developed in order to demonstrate how individual oxidative stress markers such as malondialdehyde (MDA), G-6-PD, and reduced GSH are related to the RBC surface roughness [root mean square (RMS)]. Conventional analysis of these biochemical responses were evaluated in MMH laborers (age varying between 18 years and 21 years) and a comparable control group of the same age group (with sedentary lifestyles). Peak expiratory flow rate (PEFR) and RBC surface analysis by atomic-force microscopy (AFM) and correlated scanning probe microscopy (SPM-analytical software) with corresponding image analysis were performed immediately after completion of standardized exercise (MMH) at the brickfield. A number of correlated significances and regressive linear models were developed among MDA, G-6-PD, GSH, and RBC surface roughness. It appears that these linear models might be instrumental in predicting early oxidative damages related to specific occupational hazards.

  19. Muscle fatigue in women with primary biliary cirrhosis: Spectral analysis of surface electromyography

    Institute of Scientific and Technical Information of China (English)

    Maria Rosa Biagini; Alessandro Tozzi; Antonello Grippo; Andrea Galli; Stefano Milani; Aldo Amantini

    2006-01-01

    AIM: To evaluate the myoelectric manifestations of peripheral fatigability in patients with primary biliary cirrhosis in comparison to healthy subjects. METHODS: Sixteen women with primary biliary cirrhosis without comorbidity and 13 healthy women matched for age and body mass index (BMI) completed the self reported questionnaire fatigue impact scale. All subjects underwent surface electromyography assessment of peripheral fatigability. Anterior tibial muscle isometric voluntary contraction was executed for 20 s at 80% of maximal voluntary isometric contraction. During the exercise electromyographic signal series were recorded and root mean square (expression of central drive) as well as mean and median of electromyographic signal frequency spectrum (estimates of muscle fatigability) were computed. Each subject executed the trial two times. EMG parameters were normalized, then linear regression was applied and slopes were calculated. RESULTS: Seven patients were fatigued (median fatigue impact scale score: 38, range: 26-66) and 9 were not fatigued (median fatigue impact scale score: 7, range: 0-17). The maximal voluntary isometric contraction was similar in patients (82, 54-115 N) and controls (87,74-101 N), and in patients with high (81, 54-115 N) and low fatigue impact scale scores (86, 65-106 N). Root mean square as well as mean and median of frequency spectrum slopes were compared with the Mann-Whitney U test, and no significant difference was found between fatigued and non-fatigued patients and controls. CONCLUSION: No instrumental evidence of peripheral fatigability can be found in women with primary biliary cirrhosis but no comorbidity, suggesting that fatigue in such patients may be of central origin.

  20. Using Coupled Nonnegative Matrix Factorization (cnmf) Un-Mixing for High Spectral and Spatial Resolution Data Fusion to Estimate Urban Impervious Surface and Urban Ecological Environment

    Science.gov (United States)

    Wang, T.; Zhang, H.; Lin, H.

    2017-09-01

    surfaces has increasingly roused widely interests of researchers in monitoring urban development and determining the overall environmental health of a watershed. However, studies on the impervious surface using multi-spectral imageries is insufficient and inaccurate due to the complexity of urban infrastructures base on the need to further recognize these impervious surface materials in a finer scale. Hyperspectral imageries have been proved to be sensitive to subtle spectral differences thus capable to exquisitely discriminate these similar materials while limited to the low spatial resolution. Coupled nonnegative matrix factorization (CNMF) unmixing method is one of the most physically straightforward and easily complemented hyperspectral pan-sharpening methods that could produce fused data with both high spectral and spatial resolution. This paper aimed to exploit the latent capacity and tentative validation of CNMF on the killer application of mapping urban impervious surfaces in complexed metropolitan environments like Hong Kong. Experiments showed that the fusion of high spectral and spatial resolution image could provide more accurate and comprehensive information on urban impervious surface estimation.

  1. Modelling the Passive Microwave Signature from Land Surfaces: A Review of Recent Results and Application to the L-Band SMOS SMAP Soil Moisture Retrieval Algorithms

    Science.gov (United States)

    Wigneron, J.-P.; Jackson, T. J.; O'Neill, P.; De Lannoy, G.; De Rosnay, P.; Walker, J. P.; Ferrazzoli, P.; Mironov, V.; Bircher, S.; Grant, J. P.; hide

    2017-01-01

    Two passive microwave missions are currently operating at L-band to monitor surface soil moisture (SM) over continental surfaces. The SMOS sensor, based on an innovative interferometric technology enabling multi-angular signatures of surfaces to be measured, was launched in November 2009. The SMAP sensor, based on a large mesh reflector 6 m in diameter providing a conically scanning antenna beam with a surface incidence angle of 40deg, was launched in January of 2015. Over the last decade, an intense scientific activity has focused on the development of the SM retrieval algorithms for the two missions. This activity has relied on many field (mainly tower-based) and airborne experimental campaigns, and since 2010-2011, on the SMOS and Aquarius space-borne L-band observations. It has relied too on the use of numerical, physical and semi-empirical models to simulate the microwave brightness temperature of natural scenes for a variety of scenarios in terms of system configurations (polarization, incidence angle) and soil, vegetation and climate conditions. Key components of the inversion models have been evaluated and new parameterizations of the effects of the surface temperature, soil roughness, soil permittivity, and vegetation extinction and scattering have been developed. Among others, global maps of select radiative transfer parameters have been estimated very recently. Based on this intense activity, improvements of the SMOS and SMAP SM inversion algorithms have been proposed. Some of them have already been implemented, whereas others are currently being investigated. In this paper, we present a review of the significant progress which has been made over the last decade in this field of research with a focus on L-band, and a discussion on possible applications to the SMOS and SMAP soil moisture retrieval approaches.

  2. Laser irradiation induced spectral evolution of the Laser irradiation induced spectral evolution of the surface-enhanced Raman scattering(SERS)of 4-tert-butylbenzylmercaptan on gold nanoparticles assembly

    Institute of Scientific and Technical Information of China (English)

    TONG LianMing; ZHU Tao; LIU ZhongFan

    2007-01-01

    The spectral evolution of the surface-enhanced Raman scattering (SERS) of 4-tert-butylbenzylmer-captan(4-tBBM)on gold nanopanlcles assembly under laser irradiation is reported.The reIative intensities of typical peaks in the spectrum of 4-tBBM gradually change with irradiation time.Comparison of the rate of spectral changes under several experimental conditions indicates that the surface plasmon resonance(SPR)induced heat in the gold nanoparticles assembly is the origin of the spectraI evolution.During the process of self-assembly,4-tBBM molecules do not form a compact ordered monolayer because of the spatial hindrance of the 4-tert-butyl end group.The heat induced by laser irradiation drives the 4-tBBM molecules to rearrange to a more stable orientation.

  3. A Feasibility Study for Measuring Accurate Chest Compression Depth and Rate on Soft Surfaces Using Two Accelerometers and Spectral Analysis

    Directory of Open Access Journals (Sweden)

    Sofía Ruiz de Gauna

    2016-01-01

    Full Text Available Background. Cardiopulmonary resuscitation (CPR feedback devices are being increasingly used. However, current accelerometer-based devices overestimate chest displacement when CPR is performed on soft surfaces, which may lead to insufficient compression depth. Aim. To assess the performance of a new algorithm for measuring compression depth and rate based on two accelerometers in a simulated resuscitation scenario. Materials and Methods. Compressions were provided to a manikin on two mattresses, foam and sprung, with and without a backboard. One accelerometer was placed on the chest and the second at the manikin’s back. Chest displacement and mattress displacement were calculated from the spectral analysis of the corresponding acceleration every 2 seconds and subtracted to compute the actual sternal-spinal displacement. Compression rate was obtained from the chest acceleration. Results. Median unsigned error in depth was 2.1 mm (4.4%. Error was 2.4 mm in the foam and 1.7 mm in the sprung mattress (p<0.001. Error was 3.1/2.0 mm and 1.8/1.6 mm with/without backboard for foam and sprung, respectively (p<0.001. Median error in rate was 0.9 cpm (1.0%, with no significant differences between test conditions. Conclusion. The system provided accurate feedback on chest compression depth and rate on soft surfaces. Our solution compensated mattress displacement, avoiding overestimation of compression depth when CPR is performed on soft surfaces.

  4. Experimental study of the surface thermal signature of gravity currents: application to the assessment of lava flow effusion rate

    Science.gov (United States)

    Garel, F.; Kaminski, E.; Tait, S.; Limare, A.

    2011-12-01

    During an effusive volcanic eruption, the crisis management is mainly based on the prediction of lava flows advance and its velocity. As the spreading of lava flows is mainly controlled by its rheology and the eruptive mass flux, the key question is how to evaluate them during the eruption (rather than afterwards.) A relationship between the heat flux lost by the lava at its surface and the eruption rate is likely to exist, based on the first-order argument that higher eruption rates should correspond to larger power radiated by a lava flow. The semi-empirical formula developed by Harris and co-workers (e.g. Harris et al., Bull. Volc. 2007) is currently used to estimate lava flow rate from satellite surveys yielding the surface temperatures and area of the lava flow field. However, this approach is derived from a static thermal budget of the lava flow and does not explicitly model the time-evolution of the surface thermal signal. Here we propose laboratory experiments and theoretical studies of the cooling of a viscous axisymmetric gravity current fed at constant flux rate. We first consider the isoviscous case, for which the spreading is well-know. The experiments using silicon oil and the theoretical model both reveal the establishment of a steady surface thermal structure after a transient time. The steady state is a balance between surface cooling and heat advection in the flow. The radiated heat flux in the steady regime, a few days for a basaltic lava flow, depends mainly on the effusion rate rather than on the viscosity. In this regime, one thermal survey of the radiated power could provide a consistent estimate of the flow rate if the external cooling conditions (wind) are reasonably well constrained. We continue to investigate the relationship between the thermal radiated heat flux and the effusion rate by using in the experiments fluids with temperature-dependent viscosity (glucose syrup) or undergoing solidification while cooling (PEG wax). We observe a

  5. Laser irradiation induced spectral evolution of the surface-enhanced Raman scattering(SERS) of 4-tert-butylbenzylmercaptan on gold nanoparticles assembly

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The spectral evolution of the surface-enhanced Raman scattering (SERS) of 4-tert-butylbenzylmer-captan (4-tBBM) on gold nanoparticles assembly under laser irradiation is reported. The relative intensities of typical peaks in the spectrum of 4-tBBM gradually change with irradiation time. Comparison of the rate of spectral changes under several experimental conditions indicates that the surface plasmon resonance (SPR) induced heat in the gold nanoparticles assembly is the origin of the spectral evolution. During the process of self-assembly, 4-tBBM molecules do not form a compact ordered monolayer because of the spatial hindrance of the 4-tert-butyl end group. The heat induced by laser irradiation drives the 4-tBBM molecules to rearrange to a more stable orientation.

  6. Alterations in Spectral Attributes of Surface Electromyograms after Utilization of a Foot Drop Stimulator during Post-Stroke Gait

    Directory of Open Access Journals (Sweden)

    Rakesh Pilkar

    2017-08-01

    Full Text Available BackgroundA foot drop stimulator (FDS is a rehabilitation intervention that stimulates the common peroneal nerve to facilitate ankle dorsiflexion at the appropriate time during post-stroke hemiplegic gait. Time–frequency analysis (TFA of non-stationary surface electromyograms (EMG and spectral variables such as instantaneous mean frequency (IMNF can provide valuable information on the long-term effects of FDS intervention in terms of changes in the motor unit (MU recruitment during gait, secondary to improved dorsiflexion.ObjectiveThe aim of this study was to apply a wavelet-based TFA approach to assess the changes in neuromuscular activation of the tibialis anterior (TA, soleus (SOL, and gastrocnemius (GA muscles after utilization of an FDS during gait post-stroke.MethodsSurface EMG were collected bilaterally from the TA, SOL, and GA muscles from six participants (142.9 ± 103.3 months post-stroke while walking without the FDS at baseline and 6 months post-FDS utilization. Continuous wavelet transform was performed to get the averaged time–frequency distribution of band pass filtered (20–300 Hz EMGs during multiple walking trials. IMNFs were computed during normalized gait and were averaged during the stance and swing phases. Percent changes in the energies associated with each frequency band of 25 Hz between 25 and 300 Hz were computed and compared between visits.ResultsAveraged time–frequency representations of the affected TA, SOL, and GA EMG show altered spectral attributes post-FDS utilization during normalized gait. The mean IMNF values for the affected TA were significantly lower than the unaffected TA at baseline (p = 0.026 and follow-up (p = 0.038 during normalized stance. The mean IMNF values significantly increased (p = 0.017 for the affected GA at follow-up during normalized swing. The frequency band of 250–275 Hz significantly increased in the energies post-FDS utilization for all muscles

  7. Characterization of radar (GPR) signatures and physical properties of a near-surface granular stratigraphy in the Valley of Queretaro, Mexico

    Science.gov (United States)

    Cerca, M.; Carreon-Freyre, D.

    2007-05-01

    Coupled use of GPR surveying with three different frequencies (300, 900, and 2000 MHz) and physical attributes determinations in a granular near-surface sequence gives insights into the effects of water content and type to the velocity of EM wave propagation (permittivity). Using known depth reflectors in the estimation of velocities for each frequency allowed obtaining vertical differences in velocity. Characteristic radar signatures were obtained for each of the 5 layers composing the horizontally stratified near-surface sequence studied. The sequence is composed of a cover of organic (0 - 0.5 m) and carbonated (0.5 - 1.0 m) soils over a pyroclastic (1 - 4.5 m), sandy gravel (4.5 - 5.6 m), silty sand (5.6 - 7.5 m), and welded tuff (7.5 - ? m). Selected physical attributes measured in detail each 15 cm of the sequence included grain size, relative strength, bulk dry density, water content (gravimetric and volumetric), specific density, and electrical conductivity. The correlation of physical properties with radargrams show the potential of GPR for characterizing layers with a similar set of interrelated physical attributes. However, the analysis of radar signatures assumes a certain degree of homogeneity in the attributes of a layer and the record of certain attributes depends, at least partially, of the frequency. For instance, small voids at the base of the carbonate soil were recorded as air wave hyperboles only with the 900 MHz frequency. Since no significant water content contrasts are observed in the sequence, the difference in the estimation of velocities of propagation from water content measurements using the Topp equation and the velocities obtained with the known reflector method can be associated to the contribution of dielectric losses. Thus, any model representing the bulk permittivity of clay bearing sequences should consider the effects of conductive losses. In our case, these effects can be related to the presence of different clay materials that

  8. Signature of coexistence of superconductivity and ferromagnetism in two-dimensional NbSe2 triggered by surface molecular adsorption

    Science.gov (United States)

    Zhu, Xiaojiao; Guo, Yuqiao; Cheng, Hao; Dai, Jun; An, Xingda; Zhao, Jiyin; Tian, Kangzhen; Wei, Shiqiang; Cheng Zeng, Xiao; Wu, Changzheng; Xie, Yi

    2016-04-01

    Ferromagnetism is usually deemed incompatible with superconductivity. Consequently, the coexistence of superconductivity and ferromagnetism is usually observed only in elegantly designed multi-ingredient structures in which the two competing electronic states originate from separate structural components. Here we report the use of surface molecular adsorption to induce ferromagnetism in two-dimensional superconducting NbSe2, representing the freestanding case of the coexistence of superconductivity and ferromagnetism in one two-dimensional nanomaterial. Surface-structural modulation of the ultrathin superconducting NbSe2 by polar reductive hydrazine molecules triggers a slight elongation of the covalent Nb-Se bond, which weakens the covalent interaction and enhances the ionicity of the tetravalent Nb with unpaired electrons, yielding ferromagnetic ordering. The induced ferromagnetic momentum couples with conduction electrons generating unique correlated effects of intrinsic negative magnetoresistance and the Kondo effect. We anticipate that the surface molecular adsorption will be a powerful tool to regulate spin ordering in the two-dimensional paradigm.

  9. The gravitational signature of internal flows in giant planets: Comparing the thermal wind approach with barotropic potential-surface methods

    Science.gov (United States)

    Kaspi, Y.; Davighi, J. E.; Galanti, E.; Hubbard, W. B.

    2016-09-01

    The upcoming Juno and Cassini gravity measurements of Jupiter and Saturn, respectively, will allow probing the internal dynamics of these planets through accurate analysis of their gravity spectra. To date, two general approaches have been suggested for relating the flow velocities and gravity fields. In the first, barotropic potential surface models, which naturally take into account the oblateness of the planet, are used to calculate the gravity field. However, barotropicity restricts the flows to be constant along cylinders parallel to the rotation axis. The second approach, calculated in the reference frame of the rotating planet, assumes that due to the large scale and rapid rotation of these planets, the winds are to leading order in geostrophic balance. Therefore, thermal wind balance relates the wind shear to the density gradients. While this approach can take into account any internal flow structure, it is limited to only calculating the dynamical gravity contributions, and has traditionally assumed spherical symmetry. This study comes to relate the two approaches both from a theoretical perspective, showing that they are analytically identical in the barotropic limit, and numerically, through systematically comparing the different model solutions for the gravity harmonics. For the barotropic potential surface models we employ two independent solution methods - the potential-theory and Maclaurin spheroid methods. We find that despite the sphericity assumption, in the barotropic limit the thermal wind solutions match well the barotropic oblate potential-surface solutions.

  10. Surface gravity waves and their acoustic signatures, 1-30 Hz, on the mid-Pacific sea floor.

    Science.gov (United States)

    Farrell, W E; Munk, Walter

    2013-10-01

    In 1999, Duennebier et al. deployed a hydrophone and geophone below the conjugate depth in the abyssal Pacific, midway between Hawaii and California. Real time data were transmitted for 3 yr over an abandoned ATT cable. These data have been analyzed in the frequency band 1 to 30 Hz. Between 1 and 6 Hz, the bottom data are interpreted as acoustic radiation from surface gravity waves, an extension to higher frequencies of a non-linear mechanism proposed by Longuet-Higgins in 1950 to explain microseisms. The inferred surface wave spectrum for wave lengths between 6 m and 17 cm is saturated (wind-independent) and roughly consistent with the traditional Phillips κ(-4) wave number spectrum. Shorter ocean waves have a strong wind dependence and a less steep wave number dependence. Similar features are found in the bottom record between 6 and 30 Hz. But this leads to an enigma: The derived surface spectrum inferred from the Longuet-Higgins mechanism with conventional assumptions for the dispersion relation is associated with mean square slopes that greatly exceed those derived from glitter. Regardless of the generation mechanism, the measured bottom intensities between 10 and 30 Hz are well below minimum noise standards reported in the literature.

  11. Signature of coexistence of superconductivity and ferromagnetism in two-dimensional NbSe2 triggered by surface molecular adsorption.

    Science.gov (United States)

    Zhu, Xiaojiao; Guo, Yuqiao; Cheng, Hao; Dai, Jun; An, Xingda; Zhao, Jiyin; Tian, Kangzhen; Wei, Shiqiang; Cheng Zeng, Xiao; Wu, Changzheng; Xie, Yi

    2016-04-04

    Ferromagnetism is usually deemed incompatible with superconductivity. Consequently, the coexistence of superconductivity and ferromagnetism is usually observed only in elegantly designed multi-ingredient structures in which the two competing electronic states originate from separate structural components. Here we report the use of surface molecular adsorption to induce ferromagnetism in two-dimensional superconducting NbSe2, representing the freestanding case of the coexistence of superconductivity and ferromagnetism in one two-dimensional nanomaterial. Surface-structural modulation of the ultrathin superconducting NbSe2 by polar reductive hydrazine molecules triggers a slight elongation of the covalent Nb-Se bond, which weakens the covalent interaction and enhances the ionicity of the tetravalent Nb with unpaired electrons, yielding ferromagnetic ordering. The induced ferromagnetic momentum couples with conduction electrons generating unique correlated effects of intrinsic negative magnetoresistance and the Kondo effect. We anticipate that the surface molecular adsorption will be a powerful tool to regulate spin ordering in the two-dimensional paradigm.

  12. Rapid detection and characterization of surface CO2 leakage through the real-time measurement of δ13C signatures in CO2 flux from the ground

    Science.gov (United States)

    Krevor, Samuel; Benson, Sally; Rella, Chris; Perrin, Jean-Christophe; Esposito, Ariel; Crosson, Eric

    2010-05-01

    The surface monitoring of CO2 over geologic sequestration sites will be an essential tool in the monitoring and verification of sequestration projects. Surface monitoring is the only tool that currently provides the opportunity to detect and quantify leakages on the order of 1000 tons/year CO2. Near-surface detection and quantification can be made complicated, however, due to large temporal and spatial variations in natural background CO2 fluxes from biological processes. In addition, current surface monitoring technologies, such as the use of IR spectroscopy in eddy covariance towers and aerial surveys, radioactive or noble gas isotopic tracers, and flux chamber gas measurements can generally accomplish one or two of the necessary tasks of leak detection, identification, and quantification, at both large spatial scales and high spatial resolution. It would be useful, however, to combine the utility of these technologies so that a much simplified surface monitoring program can be deployed. Carbon isotopes of CO2 provide an opportunity to distinguish between natural biogenic CO2 fluxes from the ground and CO2 leaking from a sequestration reservoir that has ultimate origins in a process giving it a distinct isotopic signature such as natural gas processing. Until recently, measuring isotopic compositions of gases was a time-consuming and expensive process utilizing mass-spectrometry, not practical for deployment in a high-resolution survey of a potential leakage site at the surface. Recent developments in commercially available instruments utilizing wavelength scanned cavity ringdown spectroscopy (WS-CRDS) and Fourier transform infrared spectroscopy (FT-IR) have made it possible to rapidly measure the isotopic composition of gases including the 13C and 12C isotopic composition of CO2 in a field setting. A portable stable carbon isotope ratio analyzer for carbon dioxide, based on wavelength scanned cavity ringdown spectroscopy, has been used to rapidly detect and

  13. The research of air pollution based on spectral features in leaf surface of Ficus microcarpa in Guangzhou, China.

    Science.gov (United States)

    Wang, Jie; Xu, Ruisong; Ma, Yueliang; Miao, Li; Cai, Rui; Chen, Yu

    2008-07-01

    Nowadays development of industry and traffic are the main contributor to city air pollution in the city of GuangZhou, China. Conventional methods for investigating atmosphere potentially harmful element pollution based on sampling and chemical analysis are time and labor consuming and relatively expensive. Reflectance spectroscopy within the visible-near-infrared region of vegetation in city has been widely used to predict atmosphere constituents due to its rapidity, convenience and accuracy. The objective of this study was to examine the possibility of using leaves reflectance spectra of vegetation as a rapid method to simultaneously assess pollutant (S, Cd, Cu, Hg, Pb, XCl, XF) in the atmosphere of the Guangzhou area. This article has studied the spectral features of polluted leaf surface of Ficus microcarpa in 1985 and 1998. According to the analysis, comprehensive assessment for the change of atmospheric condition and degrees of pollution were given. This conclusion was confirmed by the monitored data got from chemical analysis. Future study with real remote sensing data and field measurements were strongly recommended.

  14. High performance spectral-phase surface plasmon resonance biosensors based on single- and double-layer schemes

    Science.gov (United States)

    Wang, Cheng; Ho, Ho-Pui; Shum, Ping

    2013-03-01

    We have investigated the surface plasmon resonance (SPR) phase change across a range of excitation wavelengths (i.e. spectral-phase) using the Fresnel's equations and Transfer Matrix technique with emphasis on optimizing refractive index sensing performance. Having evaluated the phase change characteristics upon varying different sets of parameters, our results indicate the possibility of achieving extremely high resolution within a wide range of sample refractive index (1.3330-1.3505) at a fixed angle of incidence. We also demonstrate that the double-layer (silver/gold or copper/gold) configuration holds very promising characteristics for SPR sensing, and it is possible to achieve a detection limit of 7.9×10-9 RIU (refractive index unit) if one uses a phase measurement resolution of 2×10-4 rad. Among all the factors, material of the metal film and its thickness are found to affect performance most. This work provides a comprehensive analysis of the interplay between various system parameters.

  15. Sublimation of Ices Containing Organics and/or Minerals and Implications for Icy Bodies Surface Structure and Spectral Properties

    Science.gov (United States)

    Poch, O.; Pommerol, A.; Jost, B.; Yoldi, Z.; Carrasco, N.; Szopa, C.; Thomas, N.

    2015-12-01

    The surfaces of many objects in the Solar System comprise substantial quantities of water ice either in pure form or mixed with minerals and/or organic molecules. Sublimation is a process responsible for shaping and changing the reflectance properties of these objects. We present laboratory data on the evolution of the structure and the visible and near-infrared spectral reflectance of icy surfaces made of mixtures of water ice and non-volatile components (complex organic matter and silicates), as they undergo sublimation of the water ice under low temperature and pressure conditions (Poch et al., under review). We prepared icy surfaces which are potential analogues of ices found on comets, icy satellites or trans-neptunian objects (TNOs). The experiments were carried out in the SCITEAS simulation setup recently built as part of the Laboratory for Outflow Studies of Sublimating Materials (LOSSy) at the University of Bern (Pommerol et al., 2015a). As the water ice sublimated, we observed in situ the formation of a sublimation lag deposit, or sublimation mantle, made of the non-volatiles at the top of the samples. The texture (porosity, internal cohesiveness etc.), the activity (outbursts and ejection of mantle fragments) and the spectro-photometric properties of this mantle are found to differ strongly depending on the chemical nature of the non-volatiles, the size of their particles, the way they are mixed with the volatile component and the dust/ice mass ratio. The results also indicate how the band depths of the sub-surface water ice evolve during the build-up of the sublimation mantle. These data provide useful references for interpreting remote-sensing observations of Rosetta (see Pommerol et al., 2015b), and also New Horizons. Poch, O., et al., under review in IcarusPommerol, A., et al., 2015a, Planet. Space Sci. 109-110, 106-122. http://dx.doi.org/10.1016/j.pss.2015.02.004Pommerol, A., et al., 2015b, Astronomy and Astrophysics, in press. http://dx.doi.org/10.1051/0004-6361/201525977

  16. RING PROXY SIGNATURES

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Proxy signatures have been used to enable the transfer of digital signing power within some context and ring signatures can be used to provide the anonymity of a signer. By combining the functionalities of proxy signatures and ring signatures, this paper introduces a new concept, named ring proxy signature, which is a proxy signature generated by an anonymous member from a set of potential signers. The paper also constructs the first concrete ring proxy signature scheme based on the provably secure Schnorr's signatures and two ID-based ring proxy signature schemes. The security analysis is provided as well.

  17. Cross-spectral study of the spatial relationships in the North Pacific sea-surface temperature anomaly field. Report No. 23

    Energy Technology Data Exchange (ETDEWEB)

    Middleton, J.W.

    1980-03-01

    Cross-spectral analysis is used to examine the dependence of the temporal covariation of sea-surface temperature (SST) anomalies at pairs of spatially separated points in the North Pacific on (1) the time scale of the variations, (2) the relative displacement of the points and (3) their location within the North Pacific basin. Spatial scales considered here range from 1000 kilometers up to the width of the basin. The study focuses on cross-spectral estimates for the interannual frequency band, 0.125-0.75 yr/sup -1/ although estimates for three other bands spanning higher frequencies are also examined.

  18. Surface deformation and seismic signatures associated with the eruption cycle of Lone Star Geyser, Yellowstone National Park

    Science.gov (United States)

    Gomez, F. G.; Johnson, H. E., III; LeWinter, A. L.; Finnegan, D. C.; Sandvol, E. A.; Nayak, A.; Hurwitz, S.

    2014-12-01

    Geysers are important subjects for studying processes involved with multi-phase eruptions. As part of a larger field effort, this study applies imaging geodesy and seismology to study eruptive cycles of the Lone Star Geyser in Yellowstone National Park. Lone Star Geyser is an ideal candidate for such study, as it erupts with a nearly regular period of approximately 3 hours. The geyser includes a 5 m diameter cone that rises 2 meters above the sinter terrace, and the entire system can be viewed from a nearby hillside. Fieldwork was accomplished during April 2014. Ground-based interferometric radar (GBIR) and terrestrial laser scanning (TLS) were used to image possible surface deformations associated with Lone Star Geyer's eruption cycles. Additional observations were provided by global positioning system (GPS) measurements and six broad-band seismometers deployed in the immediate vicinity of the geyser. The GBIR and TLS were deployed approximately 65 meters from the sinter cone of the geyser. The GBIR involves a ku-band radar (1.7 cm wavelength) that is sensitive to approximately half-millimeter changes in the line-of-sight distance. Radar images were acquired every minute for 3 or more eruptions per day. Temporally redundant, overlapping interferograms were used to improve the sensitivity and interpolate a minute-wise time series of line-of-sight displacement, and efforts were made to account for possible path-delay effects resulting from water vapor around the geyser cone. Repeat (every minute) high-speed TLS scans were acquired for multiple eruption cycles over the course of two-days. Resulting measurement point spacing on the sinter cone was ~3cm. The TLS point-clouds were geo-referenced using static surveyed reflectors and scanner positions. In addition to measuring ground deformation, filtering and classification of the TLS point cloud was used to construct a mask that allows radar interferometry to exclude non-ground areas (vegetation, snow, sensors

  19. Surface layer proteins from virulent Clostridium difficile ribotypes exhibit signatures of positive selection with consequences for innate immune response.

    Science.gov (United States)

    Lynch, Mark; Walsh, Thomas A; Marszalowska, Izabela; Webb, Andrew E; MacAogain, Micheál; Rogers, Thomas R; Windle, Henry; Kelleher, Dermot; O'Connell, Mary J; Loscher, Christine E

    2017-03-23

    Clostridium difficile is a nosocomial pathogen prevalent in hospitals worldwide and increasingly common in the community. Sequence differences have been shown to be present in the Surface Layer Proteins (SLPs) from different C. difficile ribotypes (RT) however whether these differences influence severity of infection is still not clear. We used a molecular evolutionary approach to analyse SLPs from twenty-six C. difficile RTs representing different slpA sequences. We demonstrate that SLPs from RT 027 and 078 exhibit evidence of positive selection (PS). We compared the effect of these SLPs to those purified from RT 001 and 014, which did not exhibit PS, and demonstrate that the presence of sites under positive selection correlates with ability to activate macrophages. SLPs from RTs 027 and 078 induced a more potent response in macrophages, with increased levels of IL-6, IL-12p40, IL-10, MIP-1α, MIP-2 production relative to RT 001 and 014. Furthermore, RTs 027 and 078 induced higher expression of CD40, CD80 and MHC II on macrophages with decreased ability to phagocytose relative to LPS. These results tightly link sequence differences in C. difficile SLPs to disease susceptibility and severity, and suggest that positively selected sites in the SLPs may play a role in driving the emergence of hyper-virulent strains.

  20. Organochlorine pesticides in the atmosphere and surface water from the equatorial Indian Ocean: enantiomeric signatures, sources, and fate.

    Science.gov (United States)

    Huang, Yumei; Xu, Yue; Li, Jun; Xu, Weihai; Zhang, Gan; Cheng, Zhineng; Liu, Junwen; Wang, Yan; Tian, Chongguo

    2013-01-01

    Nineteen pairs of gaseous and surface seawater samples were collected along the cruise from Malaysia to the south of Bay of Bengal passing by Sri Lanka between April 12 and May 4, 2011 on the Chinese research vessel Shiyan I to investigate the latest OCP pollution status over the equatorial Indian Ocean. Significant decrease of α-HCH and γ-HCH was found in the air and dissolved water phase owing to global restriction for decades. Substantially high levels of p,p'-DDT, o,p'-DDT, trans-chlordane (TC), and cis-chlordane (CC) were observed in the water samples collected near Sri Lanka, indicating fresh continental riverine input of these compounds. Fugacity fractions suggest equilibrium of α-HCH at most sampling sites, while net volatilization for DDT isomers, TC and CC in most cases. Enantiomer fractions (EFs) of α-HCH and o,p'-DDT in the air and water samples were determined to trace the source of these compounds in the air. Racemic or close to racemic composition was found for atmospheric α-HCH and o,p'-DDT, while significant depletion of (+) enantiomer was found in the water phase, especially for o,p'-DDT (EFs = 0.310 ± 0.178). 24% of α-HCH in the lower air over the open sea of the equatorial Indian Ocean is estimated to be volatilized from local seawater, indicating that long-range transport is the main source.

  1. Comparison between Spectral perturbation and Spectral relaxation approach for unsteady heat and mass transfer by MHD mixed convection flow over an impulsively stretched vertical surface with chemical reaction effect

    Directory of Open Access Journals (Sweden)

    T. M. Agbaje

    2015-06-01

    Full Text Available In this study, the spectral perturbation method (SPM is utilized to solve the momentum, heat and mass transfer equations describing the unsteady MHD mixed convection flow over an impulsively stretched vertical surface in the presence of chemical reaction effect. The governing partial differential equations are reduced into a set of coupled non similar equations and then solved numerically using the SPM. The SPM combines the standard perturbation method idea with the Chebyshev pseudo-spectral collocation method. In order to demonstrate the accuracy and efficiency of the proposed method, the spectral perturbation (SPM numerical results are compared with numerical results generated using the spectral relaxation method (SRM and a good agreement between the two methods is observed up to a minimum of eight decimal digits. Several simulation are conducted to ascertain the accuracy of the SPM and the SRM. The computational speed of the SPM is demonstrated by comparing the SPM computational time with the SRM computational time. A residual error analysis is also conducted for the SPM and the SRM in order to further assess the accuracy of the SPM. The study shows that the spectral perturbation method (SPM is more efficient in terms of computational speed when compared with the SRM. The study also shows that the SPM can be used as an efficient and reliable tool for solving strongly nonlinear boundary value partial differential equation problems that are defined under the Williams and Rhyne [3] transformation. In addition, the study shows that accurate results can be obtained using the perturbation method and thus, the conclusions earlier drawn by researchers regarding the accuracy of perturbation methods is corrected.

  2. About group digital signatures

    National Research Council Canada - National Science Library

    Adriana Cristina Enache

    2012-01-01

    ...).A group digital signature is a digital signature with enhanced privacy features that allows members of a given group to anonymously sign messages on behalf of the group, producing a group signature...

  3. Temporal Lorentzian spectral triples

    Science.gov (United States)

    Franco, Nicolas

    2014-09-01

    We present the notion of temporal Lorentzian spectral triple which is an extension of the notion of pseudo-Riemannian spectral triple with a way to ensure that the signature of the metric is Lorentzian. A temporal Lorentzian spectral triple corresponds to a specific 3 + 1 decomposition of a possibly noncommutative Lorentzian space. This structure introduces a notion of global time in noncommutative geometry. As an example, we construct a temporal Lorentzian spectral triple over a Moyal-Minkowski spacetime. We show that, when time is commutative, the algebra can be extended to unbounded elements. Using such an extension, it is possible to define a Lorentzian distance formula between pure states with a well-defined noncommutative formulation.

  4. Real time gamma-ray signature identifier

    Science.gov (United States)

    Rowland, Mark [Alamo, CA; Gosnell, Tom B [Moraga, CA; Ham, Cheryl [Livermore, CA; Perkins, Dwight [Livermore, CA; Wong, James [Dublin, CA

    2012-05-15

    A real time gamma-ray signature/source identification method and system using principal components analysis (PCA) for transforming and substantially reducing one or more comprehensive spectral libraries of nuclear materials types and configurations into a corresponding concise representation/signature(s) representing and indexing each individual predetermined spectrum in principal component (PC) space, wherein an unknown gamma-ray signature may be compared against the representative signature to find a match or at least characterize the unknown signature from among all the entries in the library with a single regression or simple projection into the PC space, so as to substantially reduce processing time and computing resources and enable real-time characterization and/or identification.

  5. Atomic Spectral Methods for Ab Initio Molecular Electronic Energy Surfaces: Transitioning From Small-Molecule to Biomolecular-Suitable Approaches.

    Science.gov (United States)

    Mills, Jeffrey D; Ben-Nun, Michal; Rollin, Kyle; Bromley, Michael W J; Li, Jiabo; Hinde, Robert J; Winstead, Carl L; Sheehy, Jeffrey A; Boatz, Jerry A; Langhoff, Peter W

    2016-08-25

    Continuing attention has addressed incorportation of the electronically dynamical attributes of biomolecules in the largely static first-generation molecular-mechanical force fields commonly employed in molecular-dynamics simulations. We describe here a universal quantum-mechanical approach to calculations of the electronic energy surfaces of both small molecules and large aggregates on a common basis which can include such electronic attributes, and which also seems well-suited to adaptation in ab initio molecular-dynamics applications. In contrast to the more familiar orbital-product-based methodologies employed in traditional small-molecule computational quantum chemistry, the present approach is based on an "ex-post-facto" method in which Hamiltonian matrices are evaluated prior to wave function antisymmetrization, implemented here in the support of a Hilbert space of orthonormal products of many-electron atomic spectral eigenstates familiar from the van der Waals theory of long-range interactions. The general theory in its various forms incorporates the early semiempirical atoms- and diatomics-in-molecules approaches of Moffitt, Ellison, Tully, Kuntz, and others in a comprehensive mathematical setting, and generalizes the developments of Eisenschitz, London, Claverie, and others addressing electron permutation symmetry adaptation issues, completing these early attempts to treat van der Waals and chemical forces on a common basis. Exact expressions are obtained for molecular Hamiltonian matrices and for associated energy eigenvalues as sums of separate atomic and interaction-energy terms, similar in this respect to the forms of classical force fields. The latter representation is seen to also provide a long-missing general definition of the energies of individual atoms and of their interactions within molecules and matter free from subjective additional constraints. A computer code suite is described for calculations of the many-electron atomic eigenspectra and

  6. Incorporating Endmember Variability into Linear Unmixing of Coarse Resolution Imagery: Mapping Large-Scale Impervious Surface Abundance Using a Hierarchically Object-Based Spectral Mixture Analysis

    Directory of Open Access Journals (Sweden)

    Chengbin Deng

    2015-07-01

    Full Text Available As an important indicator of anthropogenic impacts on the Earth’s surface, it is of great necessity to accurately map large-scale urbanized areas for various science and policy applications. Although spectral mixture analysis (SMA can provide spatial distribution and quantitative fractions for better representations of urban areas, this technique is rarely explored with 1-km resolution imagery. This is due mainly to the absence of image endmembers associated with the mixed pixel problem. Consequently, as the most profound source of error in SMA, endmember variability has rarely been considered with coarse resolution imagery. These issues can be acute for fractional land cover mapping due to the significant spectral variations of numerous land covers across a large study area. To solve these two problems, a hierarchically object-based SMA (HOBSMA was developed (1 to extrapolate local endmembers for regional spectral library construction; and (2 to incorporate endmember variability into linear spectral unmixing of MODIS 1-km imagery for large-scale impervious surface abundance mapping. Results show that by integrating spatial constraints from object-based image segments and endmember extrapolation techniques into multiple endmember SMA (MESMA of coarse resolution imagery, HOBSMA improves the discriminations between urban impervious surfaces and other land covers with well-known spectral confusions (e.g., bare soil and water, and particularly provides satisfactory representations of urban fringe areas and small settlements. HOBSMA yields promising abundance results at the km-level scale with relatively high precision and small bias, which considerably outperforms the traditional simple mixing model and the aggregated MODIS land cover classification product.

  7. Power spectral density function and spatial autocorrelation of the ambient vibration full-wavefield generated by a distribution of spatially correlated surface sources

    Science.gov (United States)

    Lunedei, Enrico; Albarello, Dario

    2016-03-01

    Synthetic dispersion curves are here computed in the frame of an ambient-vibration full-wavefield model, which relies on the description of both ambient-vibration ground displacement and its sources as stochastic fields defined on the Earth's surface, stationary in time and homogeneous in space. In this model, previously developed for computing synthetic Horizontal-to-Vertical Spectral Ratio curves, the power spectral density function and the spatial autocorrelation of the displacement are naturally described as functions of the power spectral density function of the generating forces and of the subsoil properties (via the relevant Green's function), by also accounting for spatial correlation of these forces. Dispersion curves are computed from the displacement power spectral density function and from the spatial autocorrelation according with the well-known f-k and SPAC techniques, respectively. Two examples illustrate the way this new ambient-vibration model works, showing its possible use in better understanding the role of the surface waves in forming the dispersion curves, as well as its capability to capture some remarkable experimental findings.

  8. Narrow terahertz attenuation signatures in Bacillus thuringiensis.

    Science.gov (United States)

    Zhang, Weidong; Brown, Elliott R; Viveros, Leamon; Burris, Kellie P; Stewart, C Neal

    2014-10-01

    Terahertz absorption signatures from culture-cultivated Bacillus thuringiensis were measured with a THz photomixing spectrometer operating from 400 to 1200 GHz. We observe two distinct signatures centered at ∼955 and 1015 GHz, and attribute them to the optically coupled particle vibrational resonance (surface phonon-polariton) of Bacillus spores. This demonstrates the potential of the THz attenuation signatures as "fingerprints" for label-free biomolecular detection.

  9. Signatures of nonthermal melting

    Directory of Open Access Journals (Sweden)

    Tobias Zier

    2015-09-01

    Full Text Available Intense ultrashort laser pulses can melt crystals in less than a picosecond but, in spite of over thirty years of active research, for many materials it is not known to what extent thermal and nonthermal microscopic processes cause this ultrafast phenomenon. Here, we perform ab-initio molecular-dynamics simulations of silicon on a laser-excited potential-energy surface, exclusively revealing nonthermal signatures of laser-induced melting. From our simulated atomic trajectories, we compute the decay of five structure factors and the time-dependent structure function. We demonstrate how these quantities provide criteria to distinguish predominantly nonthermal from thermal melting.

  10. Automated Classification of Land Cover Using Landsat 8 Oli Surface Reflectance Product and Spectral Pattern Analysis Concept - Case Study in Hanoi, Vietnam

    Science.gov (United States)

    Nguyen Dinh, Duong

    2016-06-01

    Recently USGS released provisional Landsat 8 Surface Reflectance product, which allows conducting land cover mapping over large composed of number of image scenes without necessity of atmospheric correction. In this study, the authors present a new concept for automated classification of land cover. This concept is based on spectral patterns analysis of reflected bands and can be automated using predefined classification rule set constituted of spectral pattern shape, total reflected radiance index (TRRI) and ratios of spectral bands. Given a pixel vector B6 = {b1,b2,b3,b4,b5,b6} where b1, b2,...,b6 denote bands 2, 3, ...,7 of OLI sensor respectively. By using the pixel vector B6 we can construct spectral reflectance curve. Each spectral curve is featured by a shape, which can be described in simplified form of an analogue pattern, which is consisted of 15 digits of 0, 1 and 2 showing mutual relative position of spectral vertices. Value of comparison between band i and j is 2 if bj > bi, 1 if bj = bi and 0 if bj < bi. Simplified spectral pattern is defined by 15 digits as m1,2m1,3m1,4m1,5m1,6m2,3m2,4m2,5m2,6m3,4m3,5m3,6m4,5m4,6m5,6 where mi,j is result of comparison of reflectance between bi and bj and has values of 0, 1 and 2. After construction of SSP for each pixel in the input image, the original image will be decomposed to component images, which contain pixels with the same SRCS pattern. The decomposition can be written analytically by equation A = Σnk=1Ck where A stands for original image with 6 spectral bands, n is number of component images decomposed from A and Ck is component image. For this study, we use Landsat 8 OLI reflectance image LC81270452013352LGN00 and LC81270452015182LGN00. For the decomposition, we use only six reflective bands. Each land cover class is defined by SSP code, threshold values for TRRI and band ratios. Automated classification of land cover was realized with 8 classes: forest, shrub, grass, water, wetland, develop land, barren

  11. Incorporating Endmember Variability into Linear Unmixing of Coarse Resolution Imagery: Mapping Large-Scale Impervious Surface Abundance Using a Hierarchically Object-Based Spectral Mixture Analysis

    OpenAIRE

    Chengbin Deng

    2015-01-01

    As an important indicator of anthropogenic impacts on the Earth’s surface, it is of great necessity to accurately map large-scale urbanized areas for various science and policy applications. Although spectral mixture analysis (SMA) can provide spatial distribution and quantitative fractions for better representations of urban areas, this technique is rarely explored with 1-km resolution imagery. This is due mainly to the absence of image endmembers associated with the mixed pixel problem. Con...

  12. Singular equivariant spectral asymptotics of Schroedinger operators in R{sup n} and resonances of Schottky surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Weich, Tobias

    2014-06-13

    This work consists of four self-containedly presented parts. In the first part we prove equivariant spectral asymptotics for h-pseudo-differential operators for compact orthogonal group actions generalizing results of El-Houakmi and Helffer (1991) and Cassanas (2006). Using recent results for certain oscillatory integrals with singular critical sets (Ramacher 2010) we can deduce a weak equivariant Weyl law. Furthermore, we can prove a complete asymptotic expansion for the Gutzwiller trace formula without any additional condition on the group action by a suitable generalization of the dynamical assumptions on the Hamilton flow. In the second and third part we study resonance chains which have been observed in many different physical and mathematical scattering problems. In the second part we present a mathematical rigorous study of the resonance chains on three funneled Schottky surfaces. We prove the analyticity of the generalized zeta function which provide the central mathematical tool for understanding the resonance chains. Furthermore we prove for a fixed ratio between the funnel lengths and in the limit of large lengths that after a suitable rescaling the resonances in a bounded domain align equidistantly along certain lines. The position of these lines is given by the zeros of an explicit polynomial which only depends on the ratio of the funnel lengths. In the third part we provide a unifying approach to these resonance chains by generalizing dynamical zeta functions. By means of a detailed numerical study we show that these generalized zeta functions explain the mechanism that creates the chains of quantum resonance and classical Ruelle resonances for 3-disk systems as well as geometric resonances on Schottky surfaces. We also present a direct system-intrinsic definition of the continuous lines on which the resonances are strung together as a projection of an analytic variety. Additionally, this approach shows that the existence of resonance chains is

  13. A predictive model for the spectral "bioalbedo" of snow

    Science.gov (United States)

    Cook, J. M.; Hodson, A. J.; Taggart, A. J.; Mernild, S. H.; Tranter, M.

    2017-01-01

    We present the first physical model for the spectral "bioalbedo" of snow, which predicts the spectral reflectance of snowpacks contaminated with variable concentrations of red snow algae with varying diameters and pigment concentrations and then estimates the effect of the algae on snowmelt. The biooptical model estimates the absorption coefficient of individual cells; a radiative transfer scheme calculates the spectral reflectance of snow contaminated with algal cells, which is then convolved with incoming spectral irradiance to provide albedo. Albedo is then used to drive a point-surface energy balance model to calculate snowpack melt rate. The model is used to investigate the sensitivity of snow to algal biomass and pigmentation, including subsurface algal blooms. The model is then used to recreate real spectral albedo data from the High Sierra (CA, USA) and broadband albedo data from Mittivakkat Gletscher (SE Greenland). Finally, spectral "signatures" are identified that could be used to identify biology in snow and ice from remotely sensed spectral reflectance data. Our simulations not only indicate that algal blooms can influence snowpack albedo and melt rate but also highlight that "indirect" feedback related to their presence are a key uncertainty that must be investigated.

  14. Evaluating and modeling the effects of surface sampling factors on the recovery of organic chemical attribution signatures using the accelerated diffusion sampler and solvent extraction

    Energy Technology Data Exchange (ETDEWEB)

    Mo, Kai-For; Heredia-Langner, Alejandro; Fraga, Carlos G.

    2017-03-01

    In this study, an experimental design matrix was created and executed in order to test the effects of various real-world factors on the ability of the (1) accelerated diffusion sampler with solid phase micro-extraction (ADS-SPME) and (2) solvent extraction to capture organic chemical attribution signatures (CAS) from dimethyl methylphosphonate (DMMP) spiked onto painted wall board (PWB) surfaces. The DMMP CAS organic impurities sampled by ADS-SPME and solvent extraction were analyzed by gas chromatography/mass spectrometry (GC/MS). The number of detected DMMP CAS impurities and their respective GC/MS peak areas were determined as a function of DMMP stock, DMMP spiked volume, exposure time, SPME sampling time, and ADS headspace pressure. Based on the statistical analysis of experimental results, several general conclusions are made: (1) ADS-SPME with vacuum (i.e., reduced pressure) increased the amount of detected CAS impurity, as measured by GC/MS peak area, by a factor of 1.7 to 1.9 for PWB under certain experimental conditions, (2) the amount of detected CAS impurity was most influenced by spiked volume, stock, and ADS headspace pressure, (3) the ADS had no measurable effect on the number of detected DMMP impurities, that is, the ADS (with and without reduced pressure) had no practical effect on the DMMP impurity profile collected from spiked PWB, and (4) solvent extraction out performed ADS-SPME in terms of consistently capturing all or most of the targeted DMMP impurities from spiked PWB.

  15. Evaluating and modeling the effects of surface sampling factors on the recovery of organic chemical attribution signatures using the accelerated diffusion sampler and solvent extraction.

    Science.gov (United States)

    Mo, Kai-For; Heredia-Langner, Alejandro; Fraga, Carlos G

    2017-03-01

    In this study, an experimental design matrix was created and executed to test the effects of various real-world factors on the ability of (1) the accelerated diffusion sampler with solid phase micro-extraction (ADS-SPME) and (2) solvent extraction to capture organic chemical attribution signatures (CAS) from dimethyl methylphosphonate (DMMP) spiked onto painted wall board (PWB) surfaces. The DMMP CAS organic impurities sampled by ADS-SPME and solvent extraction were analyzed by gas chromatography/mass spectrometry (GC/MS). The number of detected DMMP CAS impurities and their respective GC/MS peak areas were determined as a function of DMMP stock, DMMP spiked volume, exposure time, SPME sampling time, and ADS headspace pressure. Based on the statistical analysis of experimental results, several general conclusions are made: (1) the amount of CAS impurity detected using ADS-SPME and GC/MS was most influenced by spiked volume, stock, and ADS headspace pressure, (2) reduced ADS headspace pressure increased the amount of detected CAS impurity, as measured by GC/MS peak area, by up to a factor of 1.7-1.9 compared to ADS at ambient headspace pressure, (3) the ADS had no measurable effect on the number of detected DMMP impurities, that is, ADS (with and without reduced pressure) had no practical effect on the DMMP impurity profile collected from spiked PWB, and (4) solvent extraction out performed ADS-SPME in terms of consistently capturing all or most of the targeted DMMP impurities from spiked PWB.

  16. Infrared ship signature analysis and optimisation

    NARCIS (Netherlands)

    Neele, F.P.

    2005-01-01

    The last decade has seen an increase in the awareness of the infrared signature of naval ships. New ship designs show that infrared signature reduction measures are being incorporated, such as exhaust gas cooling systems, relocation of the exhausts and surface cooling systems. Hull and superstructur

  17. Sum frequency generation vibrational spectroscopy (SFG-VS) for complex molecular surfaces and interfaces: Spectral lineshape measurement and analysis plus some controversial issues

    Science.gov (United States)

    Wang, Hong-Fei

    2016-12-01

    Sum-frequency generation vibrational spectroscopy (SFG-VS) was first developed in the 1980s and it has been proven a uniquely sensitive and surface/interface selective spectroscopic probe for characterization of the structure, conformation and dynamics of molecular surfaces and interfaces. In recent years, there have been many progresses in the development of methodology and instrumentation in the SFG-VS toolbox that have significantly broadened the application to complex molecular surfaces and interfaces. In this review, after presenting a unified view on the theory and methodology focusing on the SFG-VS spectral lineshape, as well as the new opportunities in SFG-VS applications with such developments, some of the controversial issues that have been puzzling the community are discussed. The aim of this review is to present to the researchers and students interested in molecular surfaces and interfacial sciences up-to-date perspectives complementary to the existing textbooks and reviews on SFG-VS.

  18. Sum frequency generation vibrational spectroscopy (SFG-VS) for complex molecular surfaces and interfaces: Spectral lineshape measurement and analysis plus some controversial issues

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hong-Fei

    2016-12-01

    Sum-frequency generation vibrational spectroscopy (SFG-VS) was first developed in the 1980s and it has been proven a uniquely sensitive and surface/interface selective spectroscopic probe for characterization of the structure, conformation and dynamics of molecular surfaces and interfaces. In recent years, there has been significant progress in the development of methodology and instrumentation in the SFG-VS toolbox that has significantly broadened the application to complex molecular surfaces and interfaces. In this review, after presenting a unified view on the theory and methodology focusing on the SFG-VS spectral lineshape, as well as the new opportunities in SFG-VS applications with such developments, some of the controversial issues that have been puzzling the community are to be discussed. The aim of this review is to present to the researchers and students interested in molecular surfaces and interfacial sciences up-to-date perspectives complementary to the existing textbooks and reviews on SFG-VS.

  19. Polarization signatures of airborne particulates

    Science.gov (United States)

    Raman, Prashant; Fuller, Kirk A.; Gregory, Don A.

    2013-07-01

    Exploratory research has been conducted with the aim of completely determining the polarization signatures of selected particulates as a function of wavelength. This may lead to a better understanding of the interaction between electromagnetic radiation and such materials, perhaps leading to the point detection of bio-aerosols present in the atmosphere. To this end, a polarimeter capable of measuring the complete Mueller matrix of highly scattering samples in transmission and reflection (with good spectral resolution from 300 to 1100 nm) has been developed. The polarization properties of Bacillus subtilis (surrogate for anthrax spore) are compared to ambient particulate matter species such as pollen, dust, and soot. Differentiating features in the polarization signatures of these samples have been identified, thus demonstrating the potential applicability of this technique for the detection of bio-aerosol in the ambient atmosphere.

  20. Comparing robust and physics-based sea surface temperature retrievals for high resolution, multi-spectral thermal sensors using one or multiple looks

    Energy Technology Data Exchange (ETDEWEB)

    Borel, C.C.; Clodius, W.B.; Szymanski, J.J.; Theiler, J.P.

    1999-04-04

    With the advent of multi-spectral thermal imagers such as EOS's ASTER high spatial resolution thermal imagery of the Earth's surface will soon be a reality. Previous high resolution sensors such as Landsat 5 had only one spectral channel in the thermal infrared and its utility to determine absolute sea surface temperatures was limited to 6-8 K for water warmer than 25 deg C. This inaccuracy resulted from insufficient knowledge of the atmospheric temperature and water vapor, inaccurate sensor calibration, and cooling effects of thin high cirrus clouds. The authors will present two studies of algorithms and compare their performance. The first algorithm they call robust since it retrieves sea surface temperatures accurately over a fairly wide range of atmospheric conditions using linear combinations of nadir and off-nadir brightness temperatures. The second they call physics-based because it relies on physics-based models of the atmosphere. It attempts to come up with a unique sea surface temperature which fits one set of atmospheric parameters.

  1. Development of a new spectral library classifier for airborne hyperspectral images on heterogeneous environments

    OpenAIRE

    Mende, Andre; Heiden, Uta; Bachmann, Martin; Hoja, Danielle; Buchroithner, Manfred

    2011-01-01

    The classification of hyperspectral images on heterogeneous environments without prior knowledge about the study area is a challenging task. Finding potential pure spectral signatures or endmembers (EM) of the various surface materials within an image is essential for obtaining accurate classification results. Automated endmember selection techniques, in many cases, return an unlabelled result without a relationship to a known material. This study demonstrates the potential of an automated sp...

  2. Spectral characteristic of infrared radiations of some acupoint and non-acupoint areas in human arm surface

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Using infrared spectrum detective device, we experiment onNeiguan, Laogong and Hegu acupoints of seven adult volunteers as well as contrastive points beside ones. We get 63 infrared spectrums. The experiment outcome tells us that the differences of the intensities among individuals are great, and so are the differences between acupoint and non-acupoint areas. However, the differences of spectral character are small, which indicates that infrared radiations of human body are based on the same biophysical fundament.

  3. Spectral function of the K/Si(1 1 1):B surface state: the bipolaronic CDW scenario

    Energy Technology Data Exchange (ETDEWEB)

    Tournier-Colletta, C., E-mail: tournier@lpm.u-nancy.f [Institut Jean Lamour, UMR 7198, Nancy Universite/CNRS, B.P. 239 F-54506, Vandoeuvre-les-Nancy (France); Cardenas, L.; Fagot-Revurat, Y.; Kierren, B.; Malterre, D. [Institut Jean Lamour, UMR 7198, Nancy Universite/CNRS, B.P. 239 F-54506, Vandoeuvre-les-Nancy (France)

    2010-07-15

    Very recently, new LEED, STM and ARPES measurements on the (1/3)ML K/Si(1 1 1):B interface have shed the light on the role of phonons and force to reconsider the nature of the ground state, formerly proposed to be a Mott insulator. In this paper, we present simulations of the one-electron spectral function A(E). These are based on the atomic Holstein-Hubbard model, which is relevant in the strong electron-phonon coupling limit. The exact spectral function has been analysed carefully with special attention on the gap behaviour as a function of the on-site repulsion. We show that the spectral funcion is the same for opposite values of the effective on-site repulsion. The observed reconstruction favours the negative-U{sub eff} case, which corresponds to a bipolaronic charge-ordered ground state. Finally, the ARPES lineshape is reproduced correctly with fitting parameters in agreement with the literature.

  4. Herschel / HIFI spectral line survey of the Orion Bar - Temperature and density differentiation near the PDR surface

    CERN Document Server

    Nagy, Z; Ossenkopf-Okada, V; van der Tak, F F S; Bergin, E A; Gerin, M; Joblin, C; Roellig, M; Simon, R; Stutzki, J

    2016-01-01

    Photon Dominated Regions (PDRs) are interfaces between the mainly ionized and mainly molecular material around young massive stars. Analysis of the physical and chemical structure of such regions traces the impact of far-ultraviolet radiation of young massive stars on their environment. We present results on the physical and chemical structure of the prototypical high UV-illumination edge-on Orion Bar PDR from an unbiased spectral line survey with a wide spectral coverage. A spectral scan from 480-1250 GHz and 1410-1910 GHz at 1.1 MHz resolution was obtained by the HIFI instrument onboard the Herschel Space Observatory. For molecules with multiple transitions we used rotational diagrams to obtain excitation temperatures and column densities. For species with a single detected transition we used an optically thin LTE approximation. In case of species with available collisional rates, we also performed a non-LTE analysis to obtain kinetic temperatures, H2 volume densities, and column densities. About 120 lines ...

  5. Reevaluating Surface Composition of Asteroid (4) Vesta by Comparing HED Spectral Data with Dawn Framing Camera (FC) Observations

    Science.gov (United States)

    Giebner, T.; Jaumann, R.; Schröder, S.

    2016-08-01

    This master's thesis project tries to reevaluate previous findings on asteroid (4) Vesta's surface composition by using DAWN FC Filter image ratios in a new way in order to identify HED (howardite, eucrite, diogenite) lithologies on the surface.

  6. A tool for manual endmember selection and spectral unmixing

    Science.gov (United States)

    Bateson, C. Ann; Curtiss, Brian

    1993-01-01

    Sampling a continuous radiance spectrum in many narrow contiguous spectral bands results in a high covariance between the bands. Hence, the true dimensionality of imaging spectrometer data is not determined by the number of spectral bands, but by the number of spectrally unique signatures whose mixtures reproduce the spectral variance observed in an image. Methods to unmix high dimensional multispectral data use principal components analysis to reduce the dimensionality. The variance of the spectral data is modeled as a linear combination of a finite set of endmembers in the space of the eigen-vectors that account for most of the variance. The number and characteristics of these endmembers are determined not only by the number and characteristics of the spectrally unique materials on the surface but also by processes (e.g., illumination, atmospheric scattering and absorption) affecting the signal received by the sensor. Selection of endmember spectra has typically been from a library. However, since most libraries are incomplete and do not account for the processes mentioned above, we have devised a computer display that allows researchers to explore interactively the eigenvector space of a representative and mean-corrected subset of the image data in search of extreme spectra to designate as endmembers. This display, which is based on parallel coordinates, is unique in the area of multidimensional visualization in that it includes not only a passive view of higher dimensional data but also the capability to interact and move geometrical objects in higher dimensional spaces.

  7. Efficient Threshold Signature Scheme

    Directory of Open Access Journals (Sweden)

    Sattar J Aboud

    2012-01-01

    Full Text Available In this paper, we introduce a new threshold signature RSA-typed scheme. The proposed scheme has the characteristics of un-forgeable and robustness in random oracle model. Also, signature generation and verification is entirely non-interactive. In addition, the length of the entity signature participate is restricted by a steady times of the length of the RSA signature modulus. Also, the signing process of the proposed scheme is more efficient in terms of time complexity and interaction.

  8. Satellite spectral data and archaeological reconnaissance in western Greece

    Science.gov (United States)

    Cooper, Frederick A.; Bauer, M. E.; Cullen, Brenda C.

    1991-01-01

    A Macro-geographical reconnaissance of the Western Peloponnesos adopts spectral signatures taken by Landsat-5 Thematic Mapper as a new instrument of archaeological survey in Greece. Ancient records indicate that indigenous resources contributed to the prosperity of the region. Natural resources and Ancient, Medieval, and Pre-modern Folklife in the Western Peloponnesos describes the principal lines of research. For a supervised classification of attested ancient resources, a variety of biophysical surface features were pinpointed: stone quarries, coal mines, forests of oak and silver fir, terracotta-producing clay beds, crops, and various wild but exploited shrubs such as flax.

  9. Effect of the surface oxidization and nitridation on the normal spectral emissivity of titanium alloys Ti-6Al-4V at 800-1100 K at a wavelength of 1.5 μm

    Science.gov (United States)

    Zhu, Wenjie; Shi, Deheng; Zhu, Zunlue; Sun, Jinfeng

    2016-05-01

    This work strived to model the effect of surface oxidization and nitridation on the normal spectral emissivity of Ti-6Al-4V alloys at a temperature range of 800-1100 K and a wavelength of 1.5 μm. In experiments, the detector was as close to perpendicular to the surface of the specimens as possible so that only the normal spectral emissivity was measured. Two thermocouples were symmetrically welded near the measuring area for accurate measuring and monitoring of the temperature at the surface of the specimen. The specimens were heated for 6 h at a certain temperature. During this period, the normal spectral emissivity values were measured once every 1 min during the initial 180 min, and once every 2 min thereafter. The measurements were made at certain temperatures from 800 to 1100 K in intervals of 20 K. One strong oscillation in the normal spectral emissivity was observed at each temperature. The oscillations were formed by the interference between the radiation stemming from the oxidization and nitridation layer on the specimen surface and radiation from the substrate. The uncertainty in the normal spectral emissivity caused only by the surface oxidization and nitridation was found to be approximately 9.5-22.8%, and the corresponding uncertainty in the temperature generated only by the surface oxidization and nitridation was approximately 6.9-15.5 K. The model can reproduce well the normal spectral emissivity, including the strong oscillation that occurred during the initial heating period.

  10. A spectral method for retrieving cloud optical thickness and effective radius from surface-based transmittance measurements

    Directory of Open Access Journals (Sweden)

    P. J. McBride

    2011-01-01

    Full Text Available We introduce a new multispectral method for the retrieval of optical thickness and effective radius from cloud transmittance, which is less sensitive to effective radius than cloud reflectance. Based on data from the moderate spectral resolution observations of the Solar Spectral Flux Radiometer (SSFR and Shortwave Spectroradiometer (SWS, we use the spectral shape of transmitted radiance as a means of retrieving effective radius from cloud transmittance. The observations were taken during the International Chemistry Experiment in the Arctic Lower Troposphere and at the Southern Great Plains (SGP site of the Atmospheric Radiation Measurement (ARM Climate Research Facility. The spectral shape was quantified by fitting a slope to the normalized transmittance between 1565 nm and 1634 nm. The retrieval was performed by comparing the observed slope at 1565 nm and the transmittance at 515 nm with a pre-calculated library (lookup table. An estimate of the retrieval uncertainty was provided by propagating the uncertainty of the observations through the best-fit algorithm. We compare the new retrieval with an algorithm that uses transmittance at two wavelengths, a method often used with cloud reflectance. The liquid water path (LWP is derived from the retrieved optical thickness and effective radius, assuming a cloud with effective radius varying linearly with altitude above cloud base, and compared to the retrieved liquid water path from a microwave radiometer. Retrievals from two MODIS overpasses of the SGP were also compared. The data taken from the SGP was under thicker cloud than the case used from ICEALOT, with average optical thickness of 44 and 22, respectively. For the time period with the thicker clouds, the dual-wavelength method and the slope method retrieved nearly indistinguishable results. The dual-wavelength method, however, resulted in slightly higher average relative effective radius uncertainty of 12.9 μm±12.8%, as compared to 12.8

  11. Thermophotovoltaic Spectral Control

    Energy Technology Data Exchange (ETDEWEB)

    DM DePoy; PM Fourspring; PF Baldasaro; JF Beausang; EJ Brown; MW Dashiel; KD Rahner; TD Rahmlow; JE Lazo-Wasem; EJ Gratrix; B Wemsman

    2004-06-09

    Spectral control is a key technology for thermophotovoltaic (TPV) direct energy conversion systems because only a fraction (typically less than 25%) of the incident thermal radiation has energy exceeding the diode bandgap energy, E{sub g}, and can thus be converted to electricity. The goal for TPV spectral control in most applications is twofold: (1) Maximize TPV efficiency by minimizing transfer of low energy, below bandgap photons from the radiator to the TPV diode. (2) Maximize TPV surface power density by maximizing transfer of high energy, above bandgap photons from the radiator to the TPV diode. TPV spectral control options include: front surface filters (e.g. interference filters, plasma filters, interference/plasma tandem filters, and frequency selective surfaces), back surface reflectors, and wavelength selective radiators. System analysis shows that spectral performance dominates diode performance in any practical TPV system, and that low bandgap diodes enable both higher efficiency and power density when spectral control limitations are considered. Lockheed Martin has focused its efforts on front surface tandem filters which have achieved spectral efficiencies of {approx}83% for E{sub g} = 0.52 eV and {approx}76% for E{sub g} = 0.60 eV for a 950 C radiator temperature.

  12. Quantum threshold group signature

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    In most situations, the signer is generally a single person. However, when the message is written on behalf of an organization, a valid message may require the approval or consent of several persons. Threshold signature is a solution to this problem. Generally speaking, as an authority which can be trusted by all members does not exist, a threshold signature scheme without a trusted party appears more attractive. Following some ideas of the classical Shamir’s threshold signature scheme, a quantum threshold group signature one is proposed. In the proposed scheme, only t or more of n persons in the group can generate the group signature and any t-1 or fewer ones cannot do that. In the verification phase, any t or more of n signature receivers can verify the message and any t-1 or fewer receivers cannot verify the validity of the signature.

  13. About group digital signatures

    Directory of Open Access Journals (Sweden)

    Adriana Cristina Enache

    2012-09-01

    Full Text Available

    Group signatures try to combine security (no framing, no cheating and privacy(anonymity, unlinkability.A group digital signature is a digital signature with enhanced privacy features that allows members of a given group to anonymously sign messages on behalf of the group, producing a group signature. However, in the case of dispute the identity of the signature's originator can be revealed by a designated entity (group manager. The present paper describes the main concepts about group signatures, along with a brief state of the art and shows a personal cryptographic library implemented in Java that includes two group signatures.

  14. Changes in the spectral index of skin-surface laser Doppler signals of nude mice following the injection of CT26 tumor cells.

    Science.gov (United States)

    Liu, Ju-Chi; Hsiu, Hsin; Hsu, Yi-Ping; Tsai, Hung-Chi; Kuo, Chung-Hsien

    2016-01-01

    This study investigated microcirculatory-blood-flow responses in nude mice following the injection of CT26 tumor cells by analyzing the frequency content of skin blood-flow signals recorded on the skin surface. CT26 cells were injected subcutaneously (10^4/100 μl) into the right back flank of each 7-week-old mouse. Three-minute laser Doppler flowmetry (LDF) signals were measured in 60 nude mice. The data sequences were obtained at 1, 2, and 3 weeks after injecting CT26 cells. Mouse tissue samples were cut into sections and examined microscopically to determine the condition of cancer metastasis. Spectral analysis performed after 1 week revealed a significant decrease in the relative energy contribution of the endothelium-related frequency band, and significant increases in those of the myogenic and respiration-related frequency bands of the LDF signals in the metastasis group (n=12). To the best of our knowledge, this is the first study demonstrating the feasibility of evaluating metastasis in animal subjects based on changes in noninvasively measured LDF parameters. Changes in the LDF spectral indexes can be attributed to differences in the microcirculatory regulatory activities. The present measurements performed on the skin surface provide a noninvasive and real-time method for evaluating the microcirculatory responses induced by implanting CT26 tumor cells.

  15. Herschel/HIFI spectral line survey of the Orion Bar. Temperature and density differentiation near the PDR surface

    Science.gov (United States)

    Nagy, Z.; Choi, Y.; Ossenkopf-Okada, V.; van der Tak, F. F. S.; Bergin, E. A.; Gerin, M.; Joblin, C.; Röllig, M.; Simon, R.; Stutzki, J.

    2017-02-01

    Context. Photon dominated regions (PDRs) are interfaces between the mainly ionized and mainly molecular material around young massive stars. Analysis of the physical and chemical structure of such regions traces the impact of far-ultraviolet radiation of young massive stars on their environment. Aims: We present results on the physical and chemical structure of the prototypical high UV-illumination edge-on Orion Bar PDR from an unbiased spectral line survey with a wide spectral coverage which includes lines of many important gas coolants such as [Cii], [Ci], and CO and other key molecules such as H2CO, H2O, HCN, HCO+, and SO. Methods: A spectral scan from 480-1250 GHz and 1410-1910 GHz at 1.1 MHz resolution was obtained by the HIFI instrument on board the Herschel Space Observatory. We obtained physical parameters for the observed molecules. For molecules with multiple transitions we used rotational diagrams to obtain excitation temperatures and column densities. For species with a single detected transition we used an optically thin LTE approximation. In the case of species with available collisional rates, we also performed a non-LTE analysis to obtain kinetic temperatures, H2 volume densities, and column densities. Results: About 120 lines corresponding to 29 molecules (including isotopologues) have been detected in the Herschel/HIFI line survey, including 11 transitions of CO, 7 transitions of 13CO, 6 transitions of C18O, 10 transitions of H2CO, and 6 transitions of H2O. The rotational temperatures are in the range between 22 and 146 K and the column densities are in the range between 1.8 × 1012 cm-2 and 4.5 × 1017 cm-2. For species with at least three detected transitions and available collisional excitation rates we derived a best fit kinetic temperature and H2 volume density. Most species trace kinetic temperatures in the range between 100 and 150 K and H2 volume densities in the range between 105 and 106 cm-3. The species with temperatures and

  16. Examining spectral variations in localized lunar dark mantle deposits

    Science.gov (United States)

    Jawin, Erica; Besse, Sebastien; Gaddis, Lisa R.; Sunshine, Jessica; Head, James W.; Mazrouei, Sara

    2015-01-01

    The localized lunar dark mantle deposits (DMDs) in Alphonsus, J. Herschel, and Oppenheimer craters were analyzed using visible-near-infrared spectroscopy data from the Moon Mineralogy Mapper. Spectra of these localized DMDs were analyzed for compositional and mineralogical variations within the deposits and were compared with nearby mare basalt units. Spectra of the three localized DMDs exhibited mafic absorption features indicating iron-rich compositions, although the DMDs were spectrally distinct from nearby mare basalts. All of the DMDs contained spectral signatures of glassy materials, suggesting the presence of volcanic glass in varying concentrations across the individual deposits. In addition, the albedo and spectral signatures were variable within the Alphonsus and Oppenheimer crater DMDs, suggesting variable deposit thickness and/or variations in the amount of mixing with the local substrate. Two previously unidentified localized DMDs were discovered to the northeast of Oppenheimer crater. The identification of high concentrations of volcanic glass in multiple localized DMDs in different locations suggests that the distribution of volcanic glass across the lunar surface is much more widespread than has been previously documented. The presence of volcanic glass implies an explosive, vulcanian eruption style for localized DMDs, as this allows volcanic glass to rapidly quench, inhibiting crystallization, compared to the larger hawaiian-style eruptions typical of regional DMD emplacement where black beads indicate a higher degree of crystallization. Improved understanding of the local and global distributions of volcanic glass in lunar DMDs will further constrain lunar degassing and compositional evolution throughout lunar volcanic history.

  17. Hilbert-Huang spectral analysis for characterizing the intrinsic time-scales of variability in decennial time-series of surface solar radiation

    Science.gov (United States)

    Bengulescu, Marc; Blanc, Philippe; Wald, Lucien

    2016-04-01

    An analysis of the variability of the surface solar irradiance (SSI) at different local time-scales is presented in this study. Since geophysical signals, such as long-term measurements of the SSI, are often produced by the non-linear interaction of deterministic physical processes that may also be under the influence of non-stationary external forcings, the Hilbert-Huang transform (HHT), an adaptive, noise-assisted, data-driven technique, is employed to extract locally - in time and in space - the embedded intrinsic scales at which a signal oscillates. The transform consists of two distinct steps. First, by means of the Empirical Mode Decomposition (EMD), the time-series is "de-constructed" into a finite number - often small - of zero-mean components that have distinct temporal scales of variability, termed hereinafter the Intrinsic Mode Functions (IMFs). The signal model of the components is an amplitude modulation - frequency modulation (AM - FM) one, and can also be thought of as an extension of a Fourier series having both time varying amplitude and frequency. Following the decomposition, Hilbert spectral analysis is then employed on the IMFs, yielding a time-frequency-energy representation that portrays changes in the spectral contents of the original data, with respect to time. As measurements of surface solar irradiance may possibly be contaminated by the manifestation of different type of stochastic processes (i.e. noise), the identification of real, physical processes from this background of random fluctuations is of interest. To this end, an adaptive background noise null hypothesis is assumed, based on the robust statistical properties of the EMD when applied to time-series of different classes of noise (e.g. white, red or fractional Gaussian). Since the algorithm acts as an efficient constant-Q dyadic, "wavelet-like", filter bank, the different noise inputs are decomposed into components having the same spectral shape, but that are translated to the

  18. The Variability of Solar Spectral Irradiance and Solar Surface Indices Through the Solar Activity Cycles 21-23

    Science.gov (United States)

    Deniz Goker, Umit

    2016-07-01

    A study of variations of solar spectral irradiance (SSI) in the wavelength ranges 121.5 nm-300.5 nm for the period 1981-2009 is presented. We used various data for ultraviolet (UV) spectral lines and international sunspot number (ISSN) from interactive data centers as SME (NSSDC), UARS (GDAAC), SORCE (LISIRD) and SIDC, respectively. We developed a special software for extracting the data and reduced this data by using the MATLAB. In this respect, we revealed negative correlations of intensities of UV (289.5 nm-300.5 nm) emission lines originating in the solar chromosphere with the ISSN index during the unusually prolonged minimum between the solar cycles (SCs) 23 and 24. We also compared our results with the ground-based telescopes as Solar Irradiance Platform, Stanford Data (SFO), Kodaikanal Data (KKL) and NGDC Homepage (Rome and Learmonth Solar Observatories). We studied the variations of total solar irradiance (TSI), magnetic field, sunspots/sunspot groups, Ca II K-flux, faculae and plage areas data with these ground-based telescopes, respectively. We reduced the selected data using the Phyton programming language and plot with the IDL programme. Therefore, we found that there was a decrease in the area of bright faculae and chromospheric plages while the percentage of dark faculae and plage decrease, as well. However, these decreases mainly occurred in small sunspots, contrary to this, these terms in large sunspot groups were comparable to previous SCs or even larger. Nevertheless, negative correlations between ISSN and SSI data indicate that these emissions are in close connection with the classes of sunspots/sunspot groups and "PLAGE" regions. Finally, we applied the time series of the chemical elements correspond to the wavelengths 121.5 nm-300.5 nm and compared with the ISSN data. We found an unexpected increasing in the 298.5 nm for the Fe II element. The variability of Fe II (298.5 nm) is in close connection with the plage regions and the sizes of the

  19. Global point signature for shape analysis of carpal bones

    Science.gov (United States)

    Chaudhari, Abhijit J.; Leahy, Richard M.; Wise, Barton L.; Lane, Nancy E.; Badawi, Ramsey D.; Joshi, Anand A.

    2014-02-01

    We present a method based on spectral theory for the shape analysis of carpal bones of the human wrist. We represent the cortical surface of the carpal bone in a coordinate system based on the eigensystem of the two-dimensional Helmholtz equation. We employ a metric—global point signature (GPS)—that exploits the scale and isometric invariance of eigenfunctions to quantify overall bone shape. We use a fast finite-element-method to compute the GPS metric. We capitalize upon the properties of GPS representation—such as stability, a standard Euclidean (ℓ2) metric definition, and invariance to scaling, translation and rotation—to perform shape analysis of the carpal bones of ten women and ten men from a publicly-available database. We demonstrate the utility of the proposed GPS representation to provide a means for comparing shapes of the carpal bones across populations.

  20. New spectral methods in cloud and aerosol remote sensing applications

    Science.gov (United States)

    Schmidt, K. Sebastian; McBride, Patrick; Pilewskie, Peter; Feingold, Graham; Jiang, Hongli

    2010-05-01

    We present new remote sensing techniques that rely on spectral observations of clouds and aerosols in the solar wavelength range. As a first example, we show how the effects of heterogeneous clouds, aerosols of changing optical properties, and the surface within one pixel can be distinguished by means of their spectral signatures. This example is based on data from the Gulf of Mexico Atmospheric Composition and Climate Study (GoMACCS, Houston, Texas, 2006), Large Eddy Simulations (LES) of polluted boundary layer clouds, and 3-dimensional radiative transfer calculations. In a second example, we show that the uncertainty of cloud retrievals can be improved considerably by exploiting the spectral information around liquid water absorption features in the near-infrared wavelength range. This is illustrated with spectral transmittance data from the NOAA International Chemistry Experiment in the Arctic LOwer Troposphere (ICEALOT, 2008). In contrast to reflected radiance, transmitted radiance is only weakly sensitive to cloud effective drop radius, and only cloud optical thickness can be obtained from the standard dual-channel technique. We show that effective radius and liquid water path can also be retrieved with the new spectral approach, and validate our results with microwave liquid water path measurements.

  1. Surface Roughness and Critical Exponent Analyses of Boron-Doped Diamond Films Using Atomic Force Microscopy Imaging: Application of Autocorrelation and Power Spectral Density Functions

    Science.gov (United States)

    Gupta, S.; Vierkant, G. P.

    2014-09-01

    The evolution of the surface roughness of growing metal or semiconductor thin films provides much needed information about their growth kinetics and corresponding mechanism. While some systems show stages of nucleation, coalescence, and growth, others exhibit varying microstructures for different process conditions. In view of these classifications, we report herein detailed analyses based on atomic force microscopy (AFM) characterization to extract the surface roughness and growth kinetics exponents of relatively low boron-doped diamond (BDD) films by utilizing the analytical power spectral density (PSD) and autocorrelation function (ACF) as mathematical tools. The machining industry has applied PSD for a number of years for tool design and analysis of wear and machined surface quality. Herein, we present similar analyses at the mesoscale to study the surface morphology as well as quality of BDD films grown using the microwave plasma-assisted chemical vapor deposition technique. PSD spectra as a function of boron concentration (in gaseous phase) are compared with those for samples grown without boron. We find that relatively higher boron concentration yields higher amplitudes of the longer-wavelength power spectral lines, with amplitudes decreasing in an exponential or power-law fashion towards shorter wavelengths, determining the roughness exponent ( α ≈ 0.16 ± 0.03) and growth exponent ( β ≈ 0.54), albeit indirectly. A unique application of the ACF, which is widely used in signal processing, was also applied to one-dimensional or line analyses (i.e., along the x- and y-axes) of AFM images, revealing surface topology datasets with varying boron concentration. Here, the ACF was used to cancel random surface "noise" and identify any spatial periodicity via repetitive ACF peaks or spatially correlated noise. Periodicity at shorter spatial wavelengths was observed for no doping and low doping levels, while smaller correlations were observed for relatively

  2. Spectral Methods

    CERN Document Server

    Shen, Jie; Wang, Li-Lian

    2011-01-01

    Along with finite differences and finite elements, spectral methods are one of the three main methodologies for solving partial differential equations on computers. This book provides a detailed presentation of basic spectral algorithms, as well as a systematical presentation of basic convergence theory and error analysis for spectral methods. Readers of this book will be exposed to a unified framework for designing and analyzing spectral algorithms for a variety of problems, including in particular high-order differential equations and problems in unbounded domains. The book contains a large

  3. Generalized Group Signature Scheme

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The concept of generalized group signature scheme will bepresent. Based on the generalized secret sharing scheme proposed by Lin and Ha rn, a non-interactive approach is designed for realizing such generalized group signature scheme. Using the new scheme, the authorized subsets of the group in w hich the group member can cooperate to produce the valid signature for any messa ge can be randomly specified

  4. Signatures of photon-axion conversion in the thermal spectra and polarization of neutron stars

    CERN Document Server

    Perna, Rosalba; Verde, Licia; van Adelsberg, Matthew; Jimenez, Raul

    2012-01-01

    Conversion of photons into axions under the presence of a strong magnetic field can dim the radiation from magnetized astrophysical objects. Here we perform a detailed calculation aimed at quantifying the signatures of photon-axion conversion in the spectra, light curves, and polarization of neutron stars (NSs). We take into account the energy and angle-dependence of the conversion probability and the surface thermal emission from NSs. The latter is computed from magnetized atmosphere models that include the effect of photon polarization mode conversion due to vacuum polarization. The resulting spectral models, inclusive of the general-relativistic effects of gravitational redshift and light deflection, allow us to make realistic predictions for the effects of photon to axion conversion on observed NS spectra, light curves, and polarization signals. We identify unique signatures of the conversion, such as an increase of the effective area of a hot spot as it rotates away from the observer line of sight. For a...

  5. Unconditionally Secure Quantum Signatures

    Directory of Open Access Journals (Sweden)

    Ryan Amiri

    2015-08-01

    Full Text Available Signature schemes, proposed in 1976 by Diffie and Hellman, have become ubiquitous across modern communications. They allow for the exchange of messages from one sender to multiple recipients, with the guarantees that messages cannot be forged or tampered with and that messages also can be forwarded from one recipient to another without compromising their validity. Signatures are different from, but no less important than encryption, which ensures the privacy of a message. Commonly used signature protocols—signatures based on the Rivest–Adleman–Shamir (RSA algorithm, the digital signature algorithm (DSA, and the elliptic curve digital signature algorithm (ECDSA—are only computationally secure, similar to public key encryption methods. In fact, since these rely on the difficulty of finding discrete logarithms or factoring large primes, it is known that they will become completely insecure with the emergence of quantum computers. We may therefore see a shift towards signature protocols that will remain secure even in a post-quantum world. Ideally, such schemes would provide unconditional or information-theoretic security. In this paper, we aim to provide an accessible and comprehensive review of existing unconditionally securesecure signature schemes for signing classical messages, with a focus on unconditionally secure quantum signature schemes.

  6. Radar Signature Calculation Facility

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: The calculation, analysis, and visualization of the spatially extended radar signatures of complex objects such as ships in a sea multipath environment and...

  7. Blind Collective Signature Protocol

    Directory of Open Access Journals (Sweden)

    Nikolay A. Moldovyan

    2011-06-01

    Full Text Available Using the digital signature (DS scheme specified by Belarusian DS standard there are designed the collective and blind collective DS protocols. Signature formation is performed simultaneously by all of the assigned signers, therefore the proposed protocols can be used also as protocols for simultaneous signing a contract. The proposed blind collective DS protocol represents a particular implementation of the blind multisignature schemes that is a novel type of the signature schemes. The proposed protocols are the first implementations of the multisignature schemes based on Belarusian signature standard.

  8. Extended short-wavelength spectral response of organic/(silver nanoparticles/Si nanoholes nanocomposite films) hybrid solar cells due to localized surface plasmon resonance

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Zhixin [National Laboratory of Solid State Microstructures and Jiangsu Provincial Key Laboratory of Photonic and Electronic Materials Sciences and Technology, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China); Xu, Ling, E-mail: xuling@nju.edu.cn [National Laboratory of Solid State Microstructures and Jiangsu Provincial Key Laboratory of Photonic and Electronic Materials Sciences and Technology, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China); Zhang, Wengping; Ge, Zhaoyun; Xu, Jun [National Laboratory of Solid State Microstructures and Jiangsu Provincial Key Laboratory of Photonic and Electronic Materials Sciences and Technology, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China); Su, Weining; Yu, Yao [National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093 (China); Ma, Zhongyuan; Chen, Kunji [National Laboratory of Solid State Microstructures and Jiangsu Provincial Key Laboratory of Photonic and Electronic Materials Sciences and Technology, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China)

    2015-04-15

    Highlights: • The silver nanoparticles (AgNPs)/Si nanoholes (SiNHs) nanocomposite films were fabricated. • An enhancement of total absorption in the AgNPs/SiNHs nanocomposite films at the short wavelength was exhibited. • Prototype solar cell device with AgNPs exhibits an increase of the power conversion efficiency by a factor of 2–3. - Abstract: In this letter, we investigated spectral and opto-electronic conversion properties of the inorganic/organic hybrid cells by using silver nanoparticles (AgNPs)/Si nanoholes (SiNHs) nanocomposite films, which were fabricated by the modified metal-assisted electroless etching (EE) method. It was found that the optical absorption spectra of the films with AgNPs demonstrate a clear peak and show the enhancement of total absorption at the short wavelength. The results of current–voltage (I–V) measurements show that solar cells with AgNPs exhibit an increase of the power conversion efficiency by a factor of 2–3, in comparison with those of the samples without AgNPs. Moreover, higher external quantum efficiency (EQE) values in AgNPs-decorated solar cells were confirmed in the short-wavelength spectral region (400–700 nm), which were essential to achieve high-performance photovoltaic cells. We thought these were mainly attributed to the localized surface plasmon resonance (LSPR) effects and increased light scattering of AgNPs.

  9. Determining activities of radionuclides from coincidence signatures

    Science.gov (United States)

    Warren, Glen A.; Smith, L. Eric; Aalseth, Craig E.; Ellis, Edward; Hossbach, Todd W.; Valsan, Andrei B.

    2006-05-01

    The spectral analysis of simultaneously observed photons in separate detectors may provide an invaluable tool for radioisotope identification applications. A general recursive method to determine the activity of an isotope from the observed coincidence signature rate is discussed. The method coherently accounts for effects of true coincidence summing within a single detector and detection efficiencies. A verification of the approach with computer simulations is also discussed.

  10. Effect of Surface Oxidization on the Spectral Normal Emissivity of Aluminum 3A21 at the Wavelength of 1.5 m Over the Temperature Range from 800 K to 910 K

    Science.gov (United States)

    Shi, Deheng; Zou, Fenghui; Wang, Shuai; Zhu, Zunlue; Sun, Jinfeng

    2015-04-01

    This study explores the dependence of the spectral emissivity on the temperature ranging from 800 K to 910 K for an oxidizing surface of aluminum 3A21. In this experiment, the infrared radiation stemming from the specimen is received by an InGaAs photodiode detector, which operates at the wavelength of 1.5 m with a bandwidth of about 20 nm. The temperature of the specimen surface is determined by averaging the two R-type platinum-rhodium thermocouples, which are tightly welded on the specimen surface. The spectral emissivity is reported before the first measurement over the temperature range from 800 K to 910 K. The variation of the spectral emissivity with the heating time is evaluated at a given temperature. The variation of the spectral emissivity with temperature is discussed for a given heating time. Oscillations of the spectral emissivity have been observed, which are affirmed to be connected with the thickness of the oxidization layer on the specimen surface, and formed by the interference effect between the radiation coming from the oxidization layer and the radiation stemming from the substrate. The effect of surface oxidization on the spectral emissivity of aluminum 3A21 is evaluated, and compared with that of SPHC steel. Analytical expressions of the spectral emissivity of aluminum 3A21 versus the temperature are derived at some given heating times. A conclusion is obtained that the experimental results obtained at a given heating time from 800 K to 910 K abide by the same functional form.

  11. The temporal evolution of exposed water ice-rich areas on the surface of 67P/Churyumov-Gerasimenko: spectral analysis.

    Science.gov (United States)

    Raponi, A.; Ciarniello, M.; Capaccioni, F.; Filacchione, G.; Tosi, F.; De Sanctis, M. C.; Capria, M. T.; Barucci, M. A.; Longobardo, A.; Palomba, E.; Kappel, D.; Arnold, G.; Mottola, S.; Rousseau, B.; Rinaldi, G.; Erard, S.; Bockelee-Morvan, D.; Leyrat, C.

    2016-11-01

    Water ice-rich patches have been detected on the surface of comet 67P/Churyumov-Gerasimenko by the VIRTIS hyperspectral imager on-board the Rosetta spacecraft, since the orbital insertion in late August 2014. Among those, three icy patches have been selected, and VIRTIS data have been used to analyse their properties and temporal evolution while the comet was moving towards the Sun. We performed an extensive analysis of the spectral parameters, and we applied the Hapke radiative transfer model to retrieve the abundance and grain size of water ice, as well as the mixing modalities of water ice and the ubiquitous dark refractory terrains of the surface. Study of the spatial distribution of the spectral parameters within the ice-rich patches has revealed that water ice follows different patterns associated to a bimodal distribution of the grains: 50 μm sized and 2000 μm sized, respectively in intimate and areal mixture with the dark material. In all three cases we identified different stages of the evolution of abundance of ice in the selected patches after the first detections at about 3.5 AU heliocentric distance; the spatial extension and intensity of the water ice spectral features reached a maximum after 60-100 days at about 3.0 AU, was followed by an approximately equally timed decrease, and the features were no longer visible when observed again at about 2.2 AU, before perihelion. The exposure of deeper layers is consistent with their occurrence in "active" areas where falls or landslides could have caused the occasional exposure of water ice-rich layers. After the initial exposure of the ice, the activity of the affected area increases thus causing dust removal powered by sublimation, which provides a positive feedback on the exposure itself. The process develops as the solar flux increases, and it reaches a turning point when the exposure rate is outweighed by the sublimation rate, until the complete sublimation of the patch. It is interesting to note that

  12. Technology of Electronic Signatur

    OpenAIRE

    2004-01-01

    An electronic signature uses a hash of message and an asymetrical algorithm of encryption for its generation. During verification of message on receiver side the hash of original message must be identical with the hash of received message. Electronic message is secured autentization of author and integrity of transmission date. By electronic signature it is possible to sign everything what is in digital form.

  13. Revocable Ring Signature

    Institute of Scientific and Technical Information of China (English)

    Dennis Y. W. Liu; Joseph K. Liu; Yi Mu; Willy Susilo; Duncan S. Wong

    2007-01-01

    Group signature allows the anonymity of a real signer in a group to be revoked by a trusted party called group manager. It also gives the group manager the absolute power of controlling the formation of the group. Ring signature, on the other hand, does not allow anyone to revoke the signer anonymity, while allowing the real signer to forma group (also known as a ring) arbitrarily without being controlled by any other party. In this paper, we propose a new variant for ring signature, called Revocable Ring Signature. The signature allows a real signer to form a ring arbitrarily while allowing a set of authorities to revoke the anonymity of the real signer. This new variant inherits the desirable properties from both group signature and ring signature in such a way that the real signer will be responsible for what it has signed as the anonymity is revocable by authorities while the real signer still has the freedom on ring formation. We provide a formal security model for revocable ring signature and propose an efficient construction which is proven secure under our security model.

  14. Digital Signature Management.

    Science.gov (United States)

    Hassler, Vesna; Biely, Helmut

    1999-01-01

    Describes the Digital Signature Project that was developed in Austria to establish an infrastructure for applying smart card-based digital signatures in banking and electronic-commerce applications. Discusses the need to conform to international standards, an international certification infrastructure, and security features for a public directory…

  15. Coupling of WRF meteorological model to WAM spectral wave model through sea surface roughness at the Balearic Sea: impact on wind and wave forecasts

    Science.gov (United States)

    Tolosana-Delgado, R.; Soret, A.; Jorba, O.; Baldasano, J. M.; Sánchez-Arcilla, A.

    2012-04-01

    Meteorological models, like WRF, usually describe the earth surface characteristics by tables that are function of land-use. The roughness length (z0) is an example of such approach. However, over sea z0 is modeled by the Charnock (1955) relation, linking the surface friction velocity u*2 with the roughness length z0 of turbulent air flow, z0 = α-u2* g The Charnock coefficient α may be considered a measure of roughness. For the sea surface, WRF considers a constant roughness α = 0.0185. However, there is evidence that sea surface roughness should depend on wave energy (Donelan, 1982). Spectral wave models like WAM, model the evolution and propagation of wave energy as a function of wind, and include a richer sea surface roughness description. Coupling WRF and WAM is thus a common way to improve the sea surface roughness description of WRF. WAM is a third generation wave model, solving the equation of advection of wave energy subject to input/output terms of: wind growth, energy dissipation and resonant non-linear wave-wave interactions. Third generation models work on the spectral domain. WAM considers the Charnock coefficient α a complex yet known function of the total wind input term, which depends on the wind velocity and on the Charnock coefficient again. This is solved iteratively (Janssen et al., 1990). Coupling of meteorological and wave models through a common Charnock coefficient is operationally done in medium-range met forecasting systems (e.g., at ECMWF) though the impact of coupling for smaller domains is not yet clearly assessed (Warner et al, 2010). It is unclear to which extent the additional effort of coupling improves the local wind and wave fields, in comparison to the effects of other factors, like e.g. a better bathymetry and relief resolution, or a better circulation information which might have its influence on local-scale meteorological processes (local wind jets, local convection, daily marine wind regimes, etc.). This work, within the

  16. [Research on the spectral feature and identification of the surface vegetation stressed by stored CO2 underground leakage].

    Science.gov (United States)

    Chen, Yun-Hao; Jiang, Jin-Bao; Steven, Michael D; Gong, A-Du; Li, Yi-Fan

    2012-07-01

    With the global climate warming, reducing greenhouse gas emissions becomes a focused problem for the world. The carbon capture and storage (CCS) techniques could mitigate CO2 into atmosphere, but there is a risk in case that the CO2 leaks from underground. The objective of this paper is to study the chlorophyll contents (SPAD value), relative water contents (RWC) and leaf spectra changing features of beetroot under CO2 leakage stress through field experiment. The result shows that the chlorophyll contents and RWC of beetroot under CO2 leakage stress become lower than the control beetroot', and the leaf reflectance increases in the 550 nm region and decreases in the 680nm region. A new vegetation index (R550/R680) was designed for identifying beetroot under CO2 leakage stress, and the result indicates that the vegetation index R550/R680 could identify the beetroots after CO2 leakage for 7 days. The index has strong sensitivity, stability and identification for monitoring the beetroots under CO2 stress. The result of this paper has very important meaning and application values for selecting spots of CCS project, monitoring and evaluating land-surface ecology under CO2 stress and monitoring the leakage spots by using remote sensing.

  17. Spectral Analysis

    CERN Document Server

    Cecconi, Jaures

    2011-01-01

    G. Bottaro: Quelques resultats d'analyse spectrale pour des operateurs differentiels a coefficients constants sur des domaines non bornes.- L. Garding: Eigenfuction expansions.- C. Goulaouic: Valeurs propres de problemes aux limites irreguliers: applications.- G. Grubb: Essential spectra of elliptic systems on compact manifolds.- J.Cl. Guillot: Quelques resultats recents en Scattering.- N. Schechter: Theory of perturbations of partial differential operators.- C.H. Wilcox: Spectral analysis of the Laplacian with a discontinuous coefficient.

  18. Particle size and compositional retrievals of the Chaiten volcanic ash from spaceborne, high spectral resolution infrared AIRS and IASI measurements

    Science.gov (United States)

    Prata, F.; Gangale, G.; Clarisse, L.

    2008-12-01

    The eruption of Chaiten volcano in early May 2008 produced copious amounts of ash and little SO2 gas. The ash clouds could be detected very well by several satellite instruments, but was unusual in that true- colour daytime MODIS satellite imagery showed the ash to be quite light in colour and difficult to distinguish from ordinary meteorological clouds. High spectral resolution infrared spectrometer and interferometer measurements from AIRS and IASI were analysed to investigate the spectral signature of the Chaiten ash clouds and compare these with ash clouds from other volcanoes, which generally appear much darker in visible imagery. It was found that the Chaiten ash had a distinctive spectral signature between 800 to 1200 wavenumbers and that this correlated very well with the signature expected from rhyolitic ash. A radiative transfer code and an ash microphysical model were used to retrieve the mean particle size of fine ash in the Chaiten clouds and best fits were found for rhyolitic particles with small (less than 2 micron) radii. These results suggest that infrared spectra may be used to retrieve both compositional and particle size information in ash clouds. Based on the spectral signatures found for these ash clouds, a new ash detection algorithm was designed and found to have improved sensitivity to thin (low opacity) ash clouds and low sensitivity to surface effects. The new algorithm offers the possibility of tracking ash clouds for longer periods of time and over greater distances. Results from both the AIRS and IASI measurements are presented for the May ash clouds from Chaitén volcano and compared with the signatures of ash clouds from andesitic volcanic clouds and quartz dominated windblown dust.

  19. An archaeal genomic signature

    Science.gov (United States)

    Graham, D. E.; Overbeek, R.; Olsen, G. J.; Woese, C. R.

    2000-01-01

    Comparisons of complete genome sequences allow the most objective and comprehensive descriptions possible of a lineage's evolution. This communication uses the completed genomes from four major euryarchaeal taxa to define a genomic signature for the Euryarchaeota and, by extension, the Archaea as a whole. The signature is defined in terms of the set of protein-encoding genes found in at least two diverse members of the euryarchaeal taxa that function uniquely within the Archaea; most signature proteins have no recognizable bacterial or eukaryal homologs. By this definition, 351 clusters of signature proteins have been identified. Functions of most proteins in this signature set are currently unknown. At least 70% of the clusters that contain proteins from all the euryarchaeal genomes also have crenarchaeal homologs. This conservative set, which appears refractory to horizontal gene transfer to the Bacteria or the Eukarya, would seem to reflect the significant innovations that were unique and fundamental to the archaeal "design fabric." Genomic protein signature analysis methods may be extended to characterize the evolution of any phylogenetically defined lineage. The complete set of protein clusters for the archaeal genomic signature is presented as supplementary material (see the PNAS web site, www.pnas.org).

  20. A spectral formalism for computing three-dimensional deformations due to surface loads. 2: Present-day glacial isostatic adjustment

    Science.gov (United States)

    Mitrovica, J. X.; Davis, J. L.; Shapiro, I. I.

    1994-01-01

    Using a spherically symmetric, self-gravitating, linear viscoelastic Earth model, we predict present-day three-dimensional surface deformation rates and baseline evolutions arising as a consequence of the late Pleistocene glacial cycles. In general, we use realistic models for the space-time geometry of the final late Pleistocene deglaciation event and incorporate a gravitationally self-consistent ocean meltwater redistribution. The predictions of horizontal velocity presented differ significantly, in both their amplitude and their spatial variation, from those presented in earlier analysis of others which adopted simplified models of both the late Pleistocene ice history and the Earth rheology. An important characteristic of our predicted velocity fields is that the melting of the Laurentide ice sheet over Canada is capable of contributing appreciably to the adjustment in Europe. The sensitivity of the predictions to variations in mantle rheology is investigated by considering a number of different Earth models, and by computing appropriate Frechet kernels. These calculations suggest that the sensitivity of the deformations to the Earth's rheology is significant and strongly dependent on the location of the site relative to the ancient ice sheet. The effects on the predictions of three-dimensional deformation rates of altering the ice history or adopting approximate models for the ocean meltwater redistribution have also been considered and found to be important (the former especially so). Finally, for a suite of Earth models we provide predictions of the velocity of a number of baselines in North America and Europe. We find that, in general, both radial and tangential motions contribute significantly to baseline length changes, and that these contributions are a strong function of the Earth model. We have, furthermore, found a set of Earth models which, together with the ICE-3G deglaciation chronology, produce predictions of baseline length changes that are

  1. Pore-scale spectral induced polarization (SIP) signaturesassociated with FeS biomineral transformations

    Energy Technology Data Exchange (ETDEWEB)

    Slater, Lee; Ntarlagiannis, Dimitrios; Personna, Yves R.; Hubbard, Susan

    2007-10-01

    The authors measured Spectral Induced Polarization (SIP) signatures in sand columns during (1) FeS biomineralization produced by sulfate reducing bacteria (D. vulgaris) under anaerboci conditions, and (2) subsequent biomineral dissolution upon return to an aerobic state. The low-frequency (0.1-10 Hz peak) relaxations produced during biomineralization can be modeled with a Cole-Cole formulation, from which the evolution of the polarization magnitude and relaxation length scale can be estimated. They find that the modeled time constant is consistent with the polarizable elements being biomineral encrused pores. Evolution of the model parameters is consistent with FeS surface area increases and pore-size reduction during biomineral growth, and subsequent biomineral dissolution (FeS surface area decreases and pore expansion) upon return to the aerobic state. They conclude that SIP signatures are diagnostic of pore-scale geometrical changes associated with FeS biomineralization by sulfate reducing bacteria.

  2. Theoretical foundations of NRL spectral target detection algorithms.

    Science.gov (United States)

    Schaum, Alan

    2015-11-01

    The principal spectral detection algorithms developed at the Naval Research Laboratory (NRL) over the past 20 years for use in operational systems are described. These include anomaly detectors, signature-based methods, and techniques for anomalous change detection. Newer derivations are provided that have motivated more recent work. Mathematical methods facilitating the use of forward models for the prediction of spectral signature statistics are described and a detection algorithm is derived for ocean surveillance that is based on principles of clairvoyant fusion.

  3. Machine Fault Signature Analysis

    Directory of Open Access Journals (Sweden)

    Pratesh Jayaswal

    2008-01-01

    Full Text Available The objective of this paper is to present recent developments in the field of machine fault signature analysis with particular regard to vibration analysis. The different types of faults that can be identified from the vibration signature analysis are, for example, gear fault, rolling contact bearing fault, journal bearing fault, flexible coupling faults, and electrical machine fault. It is not the intention of the authors to attempt to provide a detailed coverage of all the faults while detailed consideration is given to the subject of the rolling element bearing fault signature analysis.

  4. Spectral polarimetric light-scattering by particulate media: 1. Theory of spectral Vector Radiative Transfer

    Science.gov (United States)

    Ceolato, Romain; Riviere, Nicolas

    2016-07-01

    Spectral polarimetric light-scattering by particulate media has recently attracted growing interests for various applications due to the production of directional broadband light sources. Here the spectral polarimetric light-scattering signatures of particulate media are simulated using a numerical model based on the spectral Vector Radiative Transfer Equation (VRTE). A microphysical analysis is conducted to understand the dependence of the light-scattering signatures upon the microphysical parameters of particles. We reveal that depolarization from multiple scattering results in remarkable spectral and directional features, which are simulated by our model over a wide spectral range from visible to near-infrared. We propose to use these features to improve the inversion of the scattering problem in the fields of remote sensing, astrophysics, material science, or biomedical.

  5. Reflectance signature on sunlit crown of conifers

    Institute of Scientific and Technical Information of China (English)

    王锦地; 李小文; 项月琴

    1997-01-01

    Based on the field measurements of the reflected radiation distribution on sunlit crown surface and crown structure, the analytical approximation model of path-scattering of light in a homogeneous layer is applied to the calculation of the reflectance signature of sunlit crown. The reflectance on the sunlit crown surface is considered as the weighted sum of the direct-to-hemisphere reflectance and the hemisphere-to-hemisphere reflectance. The validation results show that the calculated reflectance signature fits the field measurement very well This paper presents details of the validation and the feasibility of the model application to nonuniform medium, such as tree crown canopies.

  6. Tight control of light trapping in surface addressable photonic crystal membranes: application to spectrally and spatially selective optical devices (Conference Presentation)

    Science.gov (United States)

    Letartre, Xavier; Blanchard, Cédric; Grillet, Christian; Jamois, Cécile; Leclercq, Jean-Louis; Viktorovitch, Pierre

    2016-04-01

    Surface addressable Photonic Crystal Membranes (PCM) are 1D or 2D photonic crystals formed in a slab waveguides where Bloch modes located above the light line are exploited. These modes are responsible for resonances in the reflection spectrum whose bandwidth can be adjusted at will. These resonances result from the coupling between a guided mode of the membrane and a free-space mode through the pattern of the photonic crystal. If broadband, these structures represent an ideal mirror to form compact vertical microcavity with 3D confinement of photons and polarization selectivity. Among numerous devices, low threshold VCSELs with remarkable and tunable modal properties have been demonstrated. Narrow band PCMs (or high Q resonators) have also been extensively used for surface addressable optoelectronic devices where an active material is embedded into the membrane, leading to the demonstration of low threshold surface emitting lasers, nonlinear bistables, optical traps... In this presentation, we will describe the main physical rules which govern the lifetime of photons in these resonant modes. More specifically, it will be emphasized that the Q factor of the PCM is determined, to the first order, by the integral overlap between the electromagnetic field distributions of the guided and free space modes and of the dielectric periodic perturbation which is applied to the homogeneous membrane to get the photonic crystal. It turns out that the symmetries of these distributions are of prime importance for the strength of the resonance. It will be shown that, by molding in-plane or vertical symmetries of Bloch modes, spectrally and spatially selective light absorbers or emitters can be designed. First proof of concept devices will be also presented.

  7. Three-dimensional simulations of near-surface convection in main-sequence stars. IV. Effect of small-scale magnetic flux concentrations on centre-to-limb variation and spectral lines

    CERN Document Server

    Beeck, Benjamin; Cameron, Robert H; Reiners, Ansgar

    2015-01-01

    Magnetic fields affect the local structure of the photosphere of stars. They can considerably influence the radiative properties near the optical surface, flow velocities, and the temperature and pressure profiles. We aim at understanding qualitatively the influence of small magnetic flux concentrations in unipolar plage regions on the centre-to-limb variation of the intensity and its contrast and on the shape of spectral line profiles in cool main-sequence stars. We analyse the bolometric and continuum intensity and its angular dependence of 24 radiative magnetohydrodynamic simulations of the near-surface layers of main-sequence stars with six different sets of stellar parameters (spectral types F to early M) and four different average magnetic field strengths (including the non-magnetic case). We also calculated disc-integrated profiles of three spectral lines. The small magnetic flux concentrations formed in the magnetic runs of simulations have a considerable impact on the intensity and its centre-to-limb...

  8. Are there molecular signatures?

    Energy Technology Data Exchange (ETDEWEB)

    Bennett, W.P.

    1995-10-01

    This report describes molecular signatures and mutational spectrum analysis. The mutation spectrum is defined as the type and location of DNA base change. There are currently about five well documented cases. Mutations and radon-associated tumors are discussed.

  9. THE ELECTRONIC SIGNATURE

    Directory of Open Access Journals (Sweden)

    Voiculescu Madalina Irena

    2009-05-01

    Full Text Available Article refers to significance and the digital signature in electronic commerce. Internet and electronic commerce open up many new opportunities for the consumer, yet, the security (or perceived lack of security of exchanging personal and financial data

  10. Advanced Missile Signature Center

    Data.gov (United States)

    Federal Laboratory Consortium — The Advanced Missile Signature Center (AMSC) is a national facility supporting the Missile Defense Agency (MDA) and other DoD programs and customers with analysis,...

  11. Technology of Electronic Signatur

    Directory of Open Access Journals (Sweden)

    Jaroslav Sadovsky

    2004-01-01

    Full Text Available An electronic signature uses a hash of message and an asymetrical algorithm of encryption for its generation. During verification of message on receiver side the hash of original message must be identical with the hash of received message. Electronic message is secured autentization of author and integrity of transmission date. By electronic signature it is possible to sign everything what is in digital form.

  12. Stateless Transitive Signature Schemes

    Institute of Scientific and Technical Information of China (English)

    MA Chun-guang; CAI Man-chun; YANG Yi-xian

    2004-01-01

    A new practical method is introduced to transform the stateful transitive signature scheme to stateless one without the loss of security. According to the approach, two concrete stateless transitive signature schemes based on Factoring and RSA are presented respectively. Under the assumption of the hardness of factoring and one-more- RSA-inversion problem, both two schemes are secure under the adaptive chosen-message attacks in random oracle model.

  13. Derivation of the canopy conductance from surface temperature and spectral indices for estimating evapotranspiration in semiarid vegetation; Monitorizacion de conductancia en vegetacion semiarida a partir de indices espectrales y temperatura de supeficie

    Energy Technology Data Exchange (ETDEWEB)

    Morillas, L.; Garcia, M.; Zarco-Tejada, P.; Ladron de Guevara, M.; Villagarcia, L.; Were, A.; Domingo, F.

    2009-07-01

    This work evaluates the possibilities for estimating stomata conductance (C) and leaf transpiration (Trf) at the ecosystem scale from radiometric indices and surface temperature. The relationships found between indices and the transpiration component of the water balance in a semiarid tussock ecosystem in SE Spain are discussed. Field data were collected from spring 2008 until winter 2009 in order to observe the annual variability of the relationships and the behaviour of spectral indices and surface temperature. (Author) 11 refs.

  14. Subpixel measurement of mangrove canopy closure via spectral mixture analysis

    Institute of Scientific and Technical Information of China (English)

    Minhe JI; Jing FENG

    2011-01-01

    Canopy closure can vary spatially within a remotely sensed image pixel,but Boolean logic inherent in traditional classification methods only works at the wholepixel level.This study attempted to decompose mangrove closure information from spectrally-mixed pixels through spectral mixture analysis (SMA) for coastal wetland management.Endmembers of different surface categories were established through signature selection and training,and memberships of a pixel with respect to the surface categories were determined via a spectral mixture model.A case study involving DigitalGlobe's Quickbird highresolution multispectral imagery of Beilun Estuary,China was used to demonstrate this approach.Mangrove canopy closure was first quantified as percent coverage through the model and then further grouped into eight ordinal categories.The model results were verified using Quickbird panchromatic data from the same acquisition.An overall accuracy of 84.4% (Kappa = 0.825) was achieved,indicating good application potential of the approach in coastal resource inventory and ecosystem management.

  15. Spectral Ranking

    CERN Document Server

    Vigna, Sebastiano

    2009-01-01

    This note tries to attempt a sketch of the history of spectral ranking, a general umbrella name for techniques that apply the theory of linear maps (in particular, eigenvalues and eigenvectors) to matrices that do not represent geometric transformations, but rather some kind of relationship between entities. Albeit recently made famous by the ample press coverage of Google's PageRank algorithm, spectral ranking was devised more than fifty years ago, almost exactly in the same terms, and has been studied in psychology and social sciences. I will try to describe it in precise and modern mathematical terms, highlighting along the way the contributions given by previous scholars.

  16. Qualitative Analysis of the Time-Frequency Signature Induced by a Reflected L-Band Signal from Time Evolving Sea Surfaces

    CERN Document Server

    Coatanhay, Arnaud

    2013-01-01

    Passive remote sensing techniques have become more and more popular for detection and characterization purposes. The advantage of using the Global Navigation Satellite Systems (GNSS) are the well known signals emitted and the availability in most areas on Earth. In the present paper, L-Band signals (including GNSS signals) are considered for oceanographic purposes. The main interest in this contribution is the analysis of the signal reflected by an evolving sea surface using time-frequency transforms. The features which occur in this domain are examined in relation to the physical phenomena: interaction of the electromagnetic waves with the moving sea surface.

  17. Observational Signatures of Binary Supermassive Black Holes

    CERN Document Server

    Roedig, Constanze; Miller, M Coleman

    2014-01-01

    Observations indicate that most massive galaxies contain a supermassive black hole, and theoretical studies suggest that when such galaxies have a major merger, the central black holes will form a binary and eventually coalesce. Here we discuss two spectral signatures of such binaries that may help distinguish them from ordinary AGN. These signatures are expected when the mass ratio between the holes is not extreme and the system is fed by a circumbinary disk. One such signature is a notch in the thermal continuum that has been predicted by other authors; we point out that it should be accompanied by a spectral revival at shorter wavelengths and also discuss its dependence on binary properties such as mass, mass ratio, and separation. In particular, we note that the wavelength $\\lambda_n$ at which the notch occurs depends on these three parameters in such a way as to make the number of systems displaying these notches $\\propto \\lambda_n^{16/3}$; longer wavelength searches are therefore strongly favored. A sec...

  18. Time-resolved spectral characterization of ring cavity surface emitting and ridge-type distributed feedback quantum cascade lasers by step-scan FT-IR spectroscopy.

    Science.gov (United States)

    Brandstetter, Markus; Genner, Andreas; Schwarzer, Clemens; Mujagic, Elvis; Strasser, Gottfried; Lendl, Bernhard

    2014-02-10

    We present the time-resolved comparison of pulsed 2nd order ring cavity surface emitting (RCSE) quantum cascade lasers (QCLs) and pulsed 1st order ridge-type distributed feedback (DFB) QCLs using a step-scan Fourier transform infrared (FT-IR) spectrometer. Laser devices were part of QCL arrays and fabricated from the same laser material. Required grating periods were adjusted to account for the grating order. The step-scan technique provided a spectral resolution of 0.1 cm(-1) and a time resolution of 2 ns. As a result, it was possible to gain information about the tuning behavior and potential mode-hops of the investigated lasers. Different cavity-lengths were compared, including 0.9 mm and 3.2 mm long ridge-type and 0.97 mm (circumference) ring-type cavities. RCSE QCLs were found to have improved emission properties in terms of line-stability, tuning rate and maximum emission time compared to ridge-type lasers.

  19. Combined Spectral and Spatial Modeling of Corn Yield Based on Aerial Images and Crop Surface Models Acquired with an Unmanned Aircraft System

    Directory of Open Access Journals (Sweden)

    Jakob Geipel

    2014-10-01

    Full Text Available Precision Farming (PF management strategies are commonly based on estimations of within-field yield potential, often derived from remotely-sensed products, e.g., Vegetation Index (VI maps. These well-established means, however, lack important information, like crop height. Combinations of VI-maps and detailed 3D Crop Surface Models (CSMs enable advanced methods for crop yield prediction. This work utilizes an Unmanned Aircraft System (UAS to capture standard RGB imagery datasets for corn grain yield prediction at three early- to mid-season growth stages. The imagery is processed into simple VI-orthoimages for crop/non-crop classification and 3D CSMs for crop height determination at different spatial resolutions. Three linear regression models are tested on their prediction ability using site-specific (i unclassified mean heights, (ii crop-classified mean heights and (iii a combination of crop-classified mean heights with according crop coverages. The models show determination coefficients \\({R}^{2}\\ of up to 0.74, whereas model (iii performs best with imagery captured at the end of stem elongation and intermediate spatial resolution (0.04m\\(\\cdot\\px\\(^{-1}\\.Following these results, combined spectral and spatial modeling, based on aerial images and CSMs, proves to be a suitable method for mid-season corn yield prediction.

  20. Study on spectral parameters and the support vector machine in surface enhanced Raman spectroscopy of serum for the detection of colon cancer

    Science.gov (United States)

    Li, Xiaozhou; Yang, Tianyue; Li, Siqi; Yao, Jun; Song, Youtao; Wang, Deli; Ding, Jianhua

    2015-11-01

    Surface enhanced Raman spectroscopy (SERS) has been recognized as an effective tool for the analysis of tissue samples and biofluids. In this work, a total of 27 spectral parameters were chosen and compared using SERS. Four parameters with the highest prediction ability were selected for further support vector machine (SVM) analysis. As a comparison, principal component analysis (PCA) was used on the same dataset for feature extraction. SVM was used with the above two data reduction methods separately to differentiate colon cancer and the control groups. Serum taken from 52 colon cancer patients and 60 healthy volunteers were collected and tested by SERS. The accuracy for Parameter-SVM was 95.0%, the sensitivity was 96.2%, and the specificity was 95.5%, which was much higher than the results using only one parameter, while for PCA-SVM, the results are 93.3%, 92.3%, and 92.9%, respectively. These results demonstrate that the SERS analysis method can be used to identify serum differences between colon cancer patients and normal people.

  1. Radiative transfer modeling of surface chemical deposits

    Science.gov (United States)

    Reichardt, Thomas A.; Kulp, Thomas J.

    2016-05-01

    Remote detection of a surface-bound chemical relies on the recognition of a pattern, or "signature," that is distinct from the background. Such signatures are a function of a chemical's fundamental optical properties, but also depend upon its specific morphology. Importantly, the same chemical can exhibit vastly different signatures depending on the size of particles composing the deposit. We present a parameterized model to account for such morphological effects on surface-deposited chemical signatures. This model leverages computational tools developed within the planetary and atmospheric science communities, beginning with T-matrix and ray-tracing approaches for evaluating the scattering and extinction properties of individual particles based on their size and shape, and the complex refractive index of the material itself. These individual-particle properties then serve as input to the Ambartsumian invariant imbedding solution for the reflectance of a particulate surface composed of these particles. The inputs to the model include parameters associated with a functionalized form of the particle size distribution (PSD) as well as parameters associated with the particle packing density and surface roughness. The model is numerically inverted via Sandia's Dakota package, optimizing agreement between modeled and measured reflectance spectra, which we demonstrate on data acquired on five size-selected silica powders over the 4-16 μm wavelength range. Agreements between modeled and measured reflectance spectra are assessed, while the optimized PSDs resulting from the spectral fitting are then compared to PSD data acquired from independent particle size measurements.

  2. Salts and radiation products on the surface of Europa

    CERN Document Server

    Brown, M E

    2013-01-01

    The surface of Europa could contain the compositional imprint of a underlying interior ocean, but competing hypotheses differ over whether spectral observations from the Galileo spacecraft show the signature of ocean evaporates or simply surface radiation products unrelated to the interior. Using adaptive optics at the W.M. Keck Observatory, we have obtained spatially resolved spectra of most of the disk of Europa at a spectral resolution ~40 times higher than seen by the Galileo spacecraft. These spectra show a previously undetected distinct signature of magnesium sulfate salts on Europa, but the magnesium sulfate is confined to the trailing hemisphere and spatially correlated with the presence of radiation products like sulfuric acid and SO2. On the leading, less irradiated, hemisphere, our observations rule out the presence of many of the proposed sulfate salts, but do show the presence of distorted water ice bands. Based on the association of the potential MgSO4, detection on the trailing side with other ...

  3. Weather and Atmospheric Effects on the Measurement and Use of Electro-Optical Signature Data

    Science.gov (United States)

    2017-02-01

    Atmospheric Effects on the Measurement and Use of Electro-Optical Signature Data RCC 469-17 February 2017 3 Table 1. General Sub- Region Terms of the...Atmospheric Effects on the Measurement and Use of Electro-Optical Signature Data RCC 469-17 February 2017 6 eye in all quantities. Multiple human eye ...on the Measurement and Use of Electro-Optical Signature Data RCC 469-17 February 2017 7 Table 4. Relative Spectral Response of the Eye λ

  4. Spectral modeling of water ice-rich areas on Ceres' surface from Dawn-VIR data analysis: abundance and grain size retrieval

    Science.gov (United States)

    Raponi, Andrea; De Sanctis, Maria Cristina; Ciarniello, Mauro; Tosi, Federico; Combe, Jean-Philippe; Frigeri, Alessandro; Zambon, Francesca; Ammannito, Eleonora; Giacomo Carrozzo, Filippo; Magni, Gianfranco; Capria, Maria Teresa; Formisano, Michelangelo; Longobardo, Andrea; Palomba, Ernesto; Pieters, Carle; Russell, Christopher T.; Raymond, Carol; Dawn/VIR Team

    2016-10-01

    Dawn spacecraft orbits around Ceres since early 2015 acquiring a huge amount of data at different spatial resolutions during the several phases of the mission. VIR, the visible and InfraRed spectrometer onboard Dawn [1] allowed to detect the principal mineralogical phases present on Ceres: a large abundance of dark component, NH4-phillosilicates and carbonates.Water has been detected in small areas on Ceres' surface by the Dawn-VIR instrument. The most obvious finding is located in Oxo crater [2]. Further detections of water have been made during the Survey observation phase (1.1 km/pixel) and High-Altitude Mapping Orbit (400 m/px) [3]. During the LAMO phase (Low Altitude Mapping Orbit), the data with increased spatial resolution (100 m/px) coming from both regions have improved the detection of water, highlighting clear diagnostic water ice absorption features. In this study, we focused on spectral modeling of VIR spectra of Oxo and another crater (lon = 227°, lat 57°), near Messor crater.The Hapke radiative transfer model [4] has been applied in order to retrieve the water ice properties. We consider two types of mixtures: areal and intimate mixing. In areal mixing, the surface is modelled as patches of pure water ice, with each photon scattered within one patch. In intimate mixing, the particles of water ice are in contact with particles of the dark terrain, and both are involved in the scattering of a single photon. The best fit with the measured spectra has been derived with the areal mixture. The water ice abundance obtained is up to 15-20% within the field of view, and the grain size retrieved is of the order of 100-200 μm. Phyllosilicates and carbonates, which are ubiquitous on Ceres surface [5], have been also detected and modeled in correspondence with the icy regions. The water ice is typically located near and within the shadows projected by the crater rims. Further analysis is required to study the thermal state of the ice and its origin

  5. Vibration signature analysis of multistage gear transmission

    Science.gov (United States)

    Choy, F. K.; Tu, Y. K.; Savage, M.; Townsend, D. P.

    1989-01-01

    An analysis is presented for multistage multimesh gear transmission systems. The analysis predicts the overall system dynamics and the transmissibility to the gear box or the enclosed structure. The modal synthesis approach of the analysis treats the uncoupled lateral/torsional model characteristics of each stage or component independently. The vibration signature analysis evaluates the global dynamics coupling in the system. The method synthesizes the interaction of each modal component or stage with the nonlinear gear mesh dynamics and the modal support geometry characteristics. The analysis simulates transient and steady state vibration events to determine the resulting torque variations, speeds, changes, rotor imbalances, and support gear box motion excitations. A vibration signature analysis examines the overall dynamic characteristics of the system, and the individual model component responses. The gear box vibration analysis also examines the spectral characteristics of the support system.

  6. Cyanobacterial signature genes.

    Science.gov (United States)

    Martin, Kirt A; Siefert, Janet L; Yerrapragada, Sailaja; Lu, Yue; McNeill, Thomas Z; Moreno, Pedro A; Weinstock, George M; Widger, William R; Fox, George E

    2003-01-01

    A comparison of 8 cyanobacterial genomes reveals that there are 181 shared genes that do not have obvious orthologs in other bacteria. These signature genes define aspects of the genotype that are uniquely cyanobacterial. Approximately 25% of these genes have been associated with some function. These signature genes may or may not be involved in photosynthesis but likely they will be in many cases. In addition, several examples of widely conserved gene order involving two or more signature genes were observed. This suggests there may be regulatory processes that have been preserved throughout the long history of the cyanobacterial phenotype. The results presented here will be especially useful because they identify which of the many genes of unassigned function are likely to be of the greatest interest.

  7. Uncertainty in hydrological signatures

    Science.gov (United States)

    McMillan, Hilary; Westerberg, Ida

    2015-04-01

    Information that summarises the hydrological behaviour or flow regime of a catchment is essential for comparing responses of different catchments to understand catchment organisation and similarity, and for many other modelling and water-management applications. Such information types derived as an index value from observed data are known as hydrological signatures, and can include descriptors of high flows (e.g. mean annual flood), low flows (e.g. mean annual low flow, recession shape), the flow variability, flow duration curve, and runoff ratio. Because the hydrological signatures are calculated from observed data such as rainfall and flow records, they are affected by uncertainty in those data. Subjective choices in the method used to calculate the signatures create a further source of uncertainty. Uncertainties in the signatures may affect our ability to compare different locations, to detect changes, or to compare future water resource management scenarios. The aim of this study was to contribute to the hydrological community's awareness and knowledge of data uncertainty in hydrological signatures, including typical sources, magnitude and methods for its assessment. We proposed a generally applicable method to calculate these uncertainties based on Monte Carlo sampling and demonstrated it for a variety of commonly used signatures. The study was made for two data rich catchments, the 50 km2 Mahurangi catchment in New Zealand and the 135 km2 Brue catchment in the UK. For rainfall data the uncertainty sources included point measurement uncertainty, the number of gauges used in calculation of the catchment spatial average, and uncertainties relating to lack of quality control. For flow data the uncertainty sources included uncertainties in stage/discharge measurement and in the approximation of the true stage-discharge relation by a rating curve. The resulting uncertainties were compared across the different signatures and catchments, to quantify uncertainty

  8. Practical quantum digital signature

    Science.gov (United States)

    Yin, Hua-Lei; Fu, Yao; Chen, Zeng-Bing

    2016-03-01

    Guaranteeing nonrepudiation, unforgeability as well as transferability of a signature is one of the most vital safeguards in today's e-commerce era. Based on fundamental laws of quantum physics, quantum digital signature (QDS) aims to provide information-theoretic security for this cryptographic task. However, up to date, the previously proposed QDS protocols are impractical due to various challenging problems and most importantly, the requirement of authenticated (secure) quantum channels between participants. Here, we present the first quantum digital signature protocol that removes the assumption of authenticated quantum channels while remaining secure against the collective attacks. Besides, our QDS protocol can be practically implemented over more than 100 km under current mature technology as used in quantum key distribution.

  9. Spectral Predictors

    Energy Technology Data Exchange (ETDEWEB)

    Ibarria, L; Lindstrom, P; Rossignac, J

    2006-11-17

    Many scientific, imaging, and geospatial applications produce large high-precision scalar fields sampled on a regular grid. Lossless compression of such data is commonly done using predictive coding, in which weighted combinations of previously coded samples known to both encoder and decoder are used to predict subsequent nearby samples. In hierarchical, incremental, or selective transmission, the spatial pattern of the known neighbors is often irregular and varies from one sample to the next, which precludes prediction based on a single stencil and fixed set of weights. To handle such situations and make the best use of available neighboring samples, we propose a local spectral predictor that offers optimal prediction by tailoring the weights to each configuration of known nearby samples. These weights may be precomputed and stored in a small lookup table. We show that predictive coding using our spectral predictor improves compression for various sources of high-precision data.

  10. Computer simulation of absolute and contrast infrared signatures from missile noses

    Science.gov (United States)

    Tofani, Alessandro

    1992-03-01

    A computer simulation was performed to obtain an estimate of the infrared radiant intensity and radiative contrast produced by missile noses. The temperature distribution on the nose was computed by taking into account the effects of aerodynamic and solar heating, sky irradiance, and radiative cooling. The corresponding absolute and contrast signatures were obtained by considering the influence of both atmosphere and target geometry, for six target classes, including cruise missiles, tactical ballistic missiles, and air-to-air and surface-to-surface missiles. Both radiant intensity and radiative contrast were computed as a function of missile altitude or missile distance for all targets. A comparison of radiative quantities in the 3- to 5-micron and 8- to 12-micron bands shows that usually the spectral region that gives the strongest signal is not the one that gives the highest contrast.

  11. Spectral Signatures of the Pentagonal Water Cluster in Bacteriorhodopsin

    Energy Technology Data Exchange (ETDEWEB)

    Baer, M; Mathias, G; Kuo, I W; Tobias, D J; Mundy, C J; Marx, D

    2008-07-25

    The exchange of protons between basic and acidic groups within proteins often involves transient protonation of amino acids and water molecules embedded in the protein matrix. One of the best studied proteins in this respect is Bacteriorohodopsin (BR), which works in the membrane of Halobacterium salinarium as a light-driven proton pump. The pumping process is triggered in the initial bR state by a photon absorption of an all-trans retinylidene chromophore, which is linked via a protonated Schiff base (pRSB) to the sidechain of Lys216. The subsequent photocycle comprises a series of intermediate states J, K, L, M, N and O, which are characterized by conformational and absorbance changes of the chromophore accompanying several elementary proton transfer processes. Upon completion of the photocycle one net proton has been transferred from the cyctoplasmic to the extracellular side against the proton gradient across the membrane. These proton exchange reactions can be monitored by time resolved infrared (IR) spectroscopy of the BR wild type and site specific mutants, which allow the localization of absorbance changes within the protein. Furthermore, these measurements have revealed the fundamental importance of internal water molecules in these processes as supported by recent large-scale QM/MM molecular dynamics studies of anharmonic IR spectra.

  12. Collider signatures of hylogenesis

    Science.gov (United States)

    Demidov, S. V.; Gorbunov, D. S.; Kirpichnikov, D. V.

    2015-02-01

    We consider collider signatures of the hylogenesis—a variant of the antibaryonic dark matter model. We obtain bounds on the model parameters from results of the first LHC run. Also we suggest several new channels relevant for probing the antibaryonic dark matter at LHC.

  13. Collider signatures of Hylogenesis

    CERN Document Server

    Demidov, S V; Kirpichnikov, D V

    2014-01-01

    We consider collider signatures of the hylogenesis --- a variant of antibaryonic dark matter model. We obtain bounds on the model parameters from results of the first LHC run. Also we suggest several new channels relevant for probing the antibaryonic dark matter at LHC.

  14. Signature transition and compactification

    CERN Document Server

    Mohseni, M

    2000-01-01

    It is shown that a change in the signature of the space-time metric together with compactification of internal dimensions could occure in a six-dimensional cosmological model. We also show that this is due to interaction with Maxwell fields having support in the internal part of the space-time.

  15. Statistical clumped isotope signatures

    NARCIS (Netherlands)

    Röckmann, T.; Popa, M. E.; Krol, M. C.; Hofmann, M. E. G.

    2016-01-01

    High precision measurements of molecules containing more than one heavy isotope may provide novel constraints on element cycles in nature. These so-called clumped isotope signatures are reported relative to the random (stochastic) distribution of heavy isotopes over all available isotopocules of a m

  16. Signatures of the Invisible

    CERN Multimedia

    Strom, D

    2003-01-01

    On the Net it is possible to take a look at art from afar via Virtual Museums. One such exhibition was recently in the New York Museum of Modern Art's branch, PS1. Entitled 'Signatures of the Invisible' it was a collaborative effort between artists and physicists (1/2 page).

  17. Exploring Habitability Markers, Biosignatures, and Their False Positives Using Spectral Models of Terrestrial Exoplanets

    Science.gov (United States)

    Schwieterman, Edward W.

    )2 feature in a variety of simulated atmospheres with different N2 abundances with both synthetic direct-imaging and transit transmission spectra. Third, I investigate observational indicators of planetary mechanisms that may generate abiotic oxygen (O2 or O3) on exoplanets, leading to potential "false positives" for life. Abiotic production of O2 from CO2 photolysis potentially leads to detectable amounts of CO as a byproduct. Oxygen build up from massive H-loss during a runaway greenhouse could leave behind more O2 than could be plausibly produced by biology. In this case density dependent O4 features would be strong and potentially indicative of this process. I investigate the strength and detectability of CO (at 2.35 and 4.6 mum) and O4 (at 0.345, 0.36, 0.38, 0.445, 0.475, 0.53, 0.57, 0.63, 1.06, and 1.27 mum) absorption for these abiotic oxygen scenarios in both transmission and direct-imaging spectroscopy. Finally, I present an interdisciplinary study of nonphotosynthetic pigments as alternative surface reflectance biosignatures, in contrast to direct photosynthetic signatures like the vegetation red edge. This study includes reflectance measurements of a variety of pigmented organisms in the laboratory, illustrating a wide range of spectral diversity. I also model the spectra of hypothetical planets containing nonphotosynthetic pigment biosignatures including the confounding spectral effects of the atmosphere. I find that these signatures could potentially be observable in disk-averaged spectra depending on the fraction of the planet containing the signature. Organisms with nonphotosynthetic pigments will produce reflectance signatures different than that of the commonly referenced vegetation red edge, and push us to broaden our understanding of what surface biosignatures might look like on Earth-like exoplanets once remote characterization of these worlds becomes possible.

  18. Quantum Gravity signatures in the Unruh effect

    CERN Document Server

    Alkofer, Natalia; Saueressig, Frank; Versteegen, Fleur

    2016-01-01

    We study quantum gravity signatures emerging from phenomenologically motivated multiscale models, spectral actions, and Causal Set Theory within the detector approach to the Unruh effect. We show that while the Unruh temperature is unaffected, Lorentz-invariant corrections to the two-point function leave a characteristic fingerprint in the induced emission rate of the accelerated detector. Generically, quantum gravity models exhibiting dynamical dimensional reduction exhibit a suppression of the Unruh rate at high energy while the rate is enhanced in Kaluza-Klein theories with compact extra dimensions. We quantify this behavior by introducing the "Unruh dimension" as the effective spacetime dimension seen by the Unruh effect and show that it is related, though not identical, to the spectral dimension used to characterize spacetime in quantum gravity. We comment on the physical origins of these effects and their relevance for black hole evaporation.

  19. Quantum gravity signatures in the Unruh effect

    Science.gov (United States)

    Alkofer, Natalia; D'Odorico, Giulio; Saueressig, Frank; Versteegen, Fleur

    2016-11-01

    We study quantum gravity signatures emerging from phenomenologically motivated multiscale models, spectral actions, and causal set theory within the detector approach to the Unruh effect. We show that while the Unruh temperature is unaffected, Lorentz-invariant corrections to the two-point function leave a characteristic fingerprint in the induced emission rate of the accelerated detector. Generically, quantum gravity models exhibiting dynamical dimensional reduction exhibit a suppression of the Unruh rate at high energy while the rate is enhanced in Kaluza-Klein theories with compact extra dimensions. We quantify this behavior by introducing the "Unruh dimension" as the effective spacetime dimension seen by the Unruh effect and show that it is related, though not identical, to the spectral dimension used to characterize spacetime in quantum gravity. We comment on the physical origins of these effects and their relevance for black hole evaporation.

  20. On Mechanism of Signature Inversion

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>The signature is associated with the invariance of a system with intrinsic quadrupole deformation under a rotation of 180° around a principal axis, and is defined in the cranking model. The signature

  1. Estimation of Soil Moisture Content from the Spectral Reflectance of Bare Soils in the 0.4–2.5 µm Domain

    Directory of Open Access Journals (Sweden)

    Sophie Fabre

    2015-02-01

    used to analyse the sensitivity of these methods to the sensor spectral resolution and the water vapour content knowledge. The spectral signatures of the database are then used to simulate the signal at the top of atmosphere with a radiative transfer model and to compute the integrated incident signal representing the spectral radiance measurements of the HYMAP airborne hyperspectral instrument. The sensor radiances are then corrected from the atmosphere by an atmospheric compensation tool to retrieve the surface reflectances. The SMC estimation methods are then applied on the retrieve spectral reflectances. The adaptation of the spectral index wavelengths to the HyMap sensor spectral bands and the application of the convex envelope and ISER models to boarder spectral bands lead to an error on the SMC estimation. The best performance is then obtained with the ISER model (RMSE of 2.9% and R2 of 0.96 while the four other methods lead to quite similar RMSE (from 6.4% to 7.8% and R² (between 0.79 and 0.83 values. In the atmosphere compensation processing, an error on the water vapour content is introduced. The most robust methods to water vapour content variations are WISOIL, NINSON, NINSOL and ISER model. The convex envelope model and NSMI index require an accurate estimation of the water vapour content in the atmosphere.

  2. Two Improved Digital Signature Schemes

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In this paper, two improved digital signature schemes are presented based on the design of directed signaturescheme [3]. The peculiarity of the system is that only if the scheme is specific recipient, the signature is authenticated.Since the scheme adds the screen of some information parameters, the difficulty of deciphered keys and the security ofdigital signature system are increased.

  3. Synthesis, spectral and surface investigation of NaSrBO{sub 3}: Sm{sup 3+} phosphor for full color down conversion in LEDs

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Vinay, E-mail: vinaykdhiman@yahoo.com [School of Physics, Shri Mata Vaishno Devi University, Katra 182320 (J and K) (India); Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein 9300 (South Africa); Bedyal, A.K. [School of Physics, Shri Mata Vaishno Devi University, Katra 182320 (J and K) (India); Pitale, Shreyas S.; Ntwaeaborwa, O.M.; Swart, H.C. [Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein 9300 (South Africa)

    2013-03-25

    Highlights: ► Suitability of present phosphors as a down conversion phosphor to fill the “yellow gap” has been explored. ► Special attention was given to check its utility to fill the 590–600 nm region (amber range). ► X-ray photoelectron spectroscopy was used to study the surface properties. ► A special analytical technique TOF-SIMS was used for studying the doping distribution. ► The images suggested a uniform distribution of the Sm{sup 3+} ions in the NaSrBO{sub 3}. -- Abstract: Orange–red emitting NaSrBO{sub 3}: Sm{sup 3+} phosphors were prepared by the combustion method using metal nitrates as precursors and urea as fuel. The particle sizes were in the range of 38–43 nm. The monoclinic structure that is in good agreement with the standard NaSrBO{sub 3} was confirmed by X-ray diffraction. Scanning electron microscopy (SEM) indicated that an agglomerated peanut like morphology was obtained. UV–VIS spectrocsopy, photoluminescence (PL) and cathodoluminescence (CL) spectroscopy were utilized to investigate the spectral properties of the phosphor. The chemical states and the distribution of the dopants in the host were analysed with X-ray photoelectron spectroscopy (XPS) and time of flight-secondary ion mass spectroscopy (TOF-SIMS), respectively. Under the excitation of near UV light, NaSrBO{sub 3}: Sm{sup 3+} exhibits the characteristic emissions resulting for the {sup 4}G{sub 5/2} → {sup 6}H{sub x/2} (x = 5, 7 and 9) transitions of Sm{sup 3+}, with a maximum intensity at 599 nm. In addition, the concentration of Sm{sup 3+} was varied in order to determine the optimum PL emission intensity. A maximum intensity was obtained from the sample with 2.0 mol% of Sm{sup 3+}. The potential applications of this phosphor, as a down conversion phosphor with an excitation wavelength of 395 nm and good CL intensity, are evaluated for the possible use as a high-color-purity phosphor in light emitting diodes (LEDs) that can fill the 590–600 nm gap and it

  4. Localized aliphatic organic material on the surface of Ceres

    Science.gov (United States)

    De Sanctis, M. C.; Ammannito, E.; McSween, H. Y.; Raponi, A.; Marchi, S.; Capaccioni, F.; Capria, M. T.; Carrozzo, F. G.; Ciarniello, M.; Fonte, S.; Formisano, M.; Frigeri, A.; Giardino, M.; Longobardo, A.; Magni, G.; McFadden, L. A.; Palomba, E.; Pieters, C. M.; Tosi, F.; Zambon, F.; Raymond, C. A.; Russell, C. T.

    2017-02-01

    Organic compounds occur in some chondritic meteorites, and their signatures on solar system bodies have been sought for decades. Spectral signatures of organics have not been unambiguously identified on the surfaces of asteroids, whereas they have been detected on cometary nuclei. Data returned by the Visible and InfraRed Mapping Spectrometer on board the Dawn spacecraft show a clear detection of an organic absorption feature at 3.4 micrometers on dwarf planet Ceres. This signature is characteristic of aliphatic organic matter and is mainly localized on a broad region of ~1000 square kilometers close to the ~50-kilometer Ernutet crater. The combined presence on Ceres of ammonia-bearing hydrated minerals, water ice, carbonates, salts, and organic material indicates a very complex chemical environment, suggesting favorable environments to prebiotic chemistry.

  5. Hybrid Baryon Signatures

    CERN Document Server

    Page, P R

    2000-01-01

    We discuss whether a low-lying hybrid baryon should be defined as a three quark - gluon bound state or as three quarks moving on an excited adiabatic potential. We show that the latter definition becomes exact, not only for very heavy quarks, but also for specific dynamics. We review the literature on the signatures of hybrid baryons, with specific reference to strong hadronic decays, electromagnetic couplings, diffractive production and production in psi decay.

  6. SMAWT Signature Test

    Science.gov (United States)

    1974-10-01

    were generally inversely proportional to the size assesments of the flash and smoke . Table 26 shows the percent of change in average judgments of...Average Time of Gunner’s View Obscuration by Smoke During Firings From the Wood Line .. .. ..... ..... ...... ..... .. 18 7. Average Obscuration Times...of Gunner’s View Obscuration by Smoke - Grass Line 19 8. Normalized Comparisons of the Relative Grades Assigned to Systems Signature Components

  7. Acid weathering of basalt and basaltic glass: 2. Effects of microscopic alteration textures on spectral properties

    Science.gov (United States)

    Smith, Rebecca J.; Horgan, Briony H. N.; Mann, Paul; Cloutis, Edward A.; Christensen, Philip R.

    2017-01-01

    Acid alteration has long been proposed for the Martian surface, and so it is important to understand how the resulting alteration textures affect surface spectra. Two basaltic materials of varying crystallinity were altered in two different H2SO4 solutions (pH 1 and pH 3) for 220 days. The unaltered and altered samples were studied in the visible and near infrared (VNIR) and thermal infrared (TIR), and select samples were chosen for scanning electron microscopy analysis. Materials altered in pH 3 solutions showed little to no physical alteration, and their spectral signatures changed very little. In contrast, all materials altered in pH 1 acid displayed silica-rich alteration textures, and the morphology differed based on starting material crystallinity. The more crystalline material displayed extensive alteration reaching into the sample interiors and had weaker silica spectral features. The glass sample developed alteration layers tens of microns thick, exhibiting amorphous silica-rich spectral features that completely obscured the substrate. Thus, the strong absorption coefficient of silica effectively decreases the penetration depth of TIR spectral measurements, causing silica abundances to be grossly overestimated in remote sensing data. Additionally, glass samples with silica layers exhibited distinct concave up blue spectral slopes in the VNIR. Spectra from the northern lowland plains of Mars are modeled with high abundances of amorphous silica and exhibit concave up blue spectral slopes and are thus consistent with acid altered basaltic glass. Therefore, we conclude that large regions of the Martian surface may have formed through the interaction of basaltic glass with strongly acidic fluids.

  8. Wheat signature modeling and analysis for improved training statistics

    Science.gov (United States)

    Nalepka, R. F. (Principal Investigator); Malila, W. A.; Cicone, R. C.; Gleason, J. M.

    1976-01-01

    The author has identified the following significant results. The spectral, spatial, and temporal characteristics of wheat and other signatures in LANDSAT multispectral scanner data were examined through empirical analysis and simulation. Irrigation patterns varied widely within Kansas; 88 percent of wheat acreage in Finney was irrigated and 24 percent in Morton, as opposed to less than 3 percent for western 2/3's of the State. The irrigation practice was definitely correlated with the observed spectral response; wheat variety differences produced observable spectral differences due to leaf coloration and different dates of maturation. Between-field differences were generally greater than within-field differences, and boundary pixels produced spectral features distinct from those within field centers. Multiclass boundary pixels contributed much of the observed bias in proportion estimates. The variability between signatures obtained by different draws of training data decreased as the sample size became larger; also, the resulting signatures became more robust and the particular decision threshold value became less important.

  9. Feedback at the Working Surface : A Joint X-ray and Low-Frequency Radio Spectral Study of the Cocoon Shock in Cygnus A

    NARCIS (Netherlands)

    Wise, Michael W.; Rafferty, D. A.; McKean, J. P.

    We report on preliminary results from a joint spectral analysis of the cocoon shock region in Cygnus A using deep archival Chandra data and new low-frequency radio data from LOFAR. Being both bright in X-rays and the most powerful radio source in the local universe, the FRII radio galaxy Cygnus A

  10. On Constructing Certificateless Proxy Signature from Certificateless Signature

    Institute of Scientific and Technical Information of China (English)

    WAN Zhong-mei; LAI Xue-jia; WENG Jian; HONG Xuan; LONG Yu; JIA Wei-wei

    2008-01-01

    In proxy signature schemes,an original signer A delegates its signing capability to a proxy signer B,in such a way that B can sign message on behalf of A.The recipient of the final message verifies at the same time that B computes the signature and that A has delegated its signing capability to B.Recently many identity-based (ID-based) proxy signature schemes have been proposed,however,the problem of key escrow is inherent in this setting.Certificateless cryptography can overcome the key escrow problem.In this paper,we present a general security model for certificateless proxy signature scheme.Then,we give a method to construct a secure certificateless proxy scheme from a secure certificateless signature scheme,and prove that the security of the construction can be reduced to the security of the original certificateless signature scheme.

  11. Molecular signatures of ribosomal evolution.

    Science.gov (United States)

    Roberts, Elijah; Sethi, Anurag; Montoya, Jonathan; Woese, Carl R; Luthey-Schulten, Zaida

    2008-09-16

    Ribosomal signatures, idiosyncrasies in the ribosomal RNA (rRNA) and/or proteins, are characteristic of the individual domains of life. As such, insight into the early evolution of the domains can be gained from a comparative analysis of their respective signatures in the translational apparatus. In this work, we identify signatures in both the sequence and structure of the rRNA and analyze their contributions to the universal phylogenetic tree using both sequence- and structure-based methods. Domain-specific ribosomal proteins can be considered signatures in their own right. Although it is commonly assumed that they developed after the universal ribosomal proteins, we present evidence that at least one may have been present before the divergence of the organismal lineages. We find correlations between the rRNA signatures and signatures in the ribosomal proteins showing that the rRNA signatures coevolved with both domain-specific and universal ribosomal proteins. Finally, we show that the genomic organization of the universal ribosomal components contains these signatures as well. From these studies, we propose the ribosomal signatures are remnants of an evolutionary-phase transition that occurred as the cell lineages began to coalesce and so should be reflected in corresponding signatures throughout the fabric of the cell and its genome.

  12. Signature CERN-URSS

    CERN Document Server

    Jentschke,W

    1975-01-01

    Le DG W.Jentschke souhaite la bienvenue à l'assemblée et aux invités pour la signature du protocole entre le Cern et l'URSS qui est un événement important. C'est en 1955 que 55 visiteurs soviétiques ont visité le Cern pour la première fois. Le premier DG au Cern, F.Bloch, et Mons.Amaldi sont aussi présents. Tandis que le discours anglais de W.Jentschke est traduit en russe, le discours russe de Mons.Morozov est traduit en anglais.

  13. The signature package on Witt spaces, II. Higher signatures

    CERN Document Server

    Albin, Pierre; Mazzeo, Rafe; Piazza, Paolo

    2009-01-01

    This is a sequel to the paper "The signature package on Witt spaces, I. Index classes" by the same authors. In the first part we investigated, via a parametrix construction, the regularity properties of the signature operator on a stratified Witt pseudomanifold, proving, in particular, that one can define a K-homology signature class. We also established the existence of an analytic index class for the signature operator twisted by a C^*_r\\Gamma Mischenko bundle and proved that the K-homology signature class is mapped to the signature index class by the assembly map. In this paper we continue our study, showing that the signature index class is invariant under rational Witt bordisms and stratified homotopies. We are also able to identify this analytic class with the topological analogue of the Mischenko symmetric signature recently defined by Banagl. Finally, we define Witt-Novikov higher signatures and show that our analytic results imply a purely topological theorem, namely that the Witt-Novikov higher sign...

  14. Identity-based threshold signature and mediated proxy signature schemes

    Institute of Scientific and Technical Information of China (English)

    YU Yong; YANG Bo; SUN Ying

    2007-01-01

    Proxy signature schemes allow an original signer to delegate his signing rights to a proxy signer. However, many proxy signature schemes have the defect which is the inability to solve the proxy revocation problem. In this article, we firstly propose an identity-based threshold signature scheme and show that it has the properties of unforgeability and robustness. In our threshold signature scheme, we adopt such a method that the private key associated with an identity rather than the master key is shared. Then, based on the threshold signature scheme, an identity-based mediated proxy signature scheme is proposed where a security mediator (SEM) is introduced to help a proxy signer to generate valid proxy signatures, examine whether a proxy signer signs according to the warrant, and check the revocation of a proxy signer. It is shown that the proposed scheme satisfies all the security requirements of a secure proxy signature. Moreover, a proxy signer must cooperate with the SEM to generate a valid proxy signature, which makes the new scheme have an effective and fast proxy revocation.

  15. SPAM- SPECTRAL ANALYSIS MANAGER (UNIX VERSION)

    Science.gov (United States)

    Solomon, J. E.

    1994-01-01

    The Spectral Analysis Manager (SPAM) was developed to allow easy qualitative analysis of multi-dimensional imaging spectrometer data. Imaging spectrometers provide sufficient spectral sampling to define unique spectral signatures on a per pixel basis. Thus direct material identification becomes possible for geologic studies. SPAM provides a variety of capabilities for carrying out interactive analysis of the massive and complex datasets associated with multispectral remote sensing observations. In addition to normal image processing functions, SPAM provides multiple levels of on-line help, a flexible command interpretation, graceful error recovery, and a program structure which can be implemented in a variety of environments. SPAM was designed to be visually oriented and user friendly with the liberal employment of graphics for rapid and efficient exploratory analysis of imaging spectrometry data. SPAM provides functions to enable arithmetic manipulations of the data, such as normalization, linear mixing, band ratio discrimination, and low-pass filtering. SPAM can be used to examine the spectra of an individual pixel or the average spectra over a number of pixels. SPAM also supports image segmentation, fast spectral signature matching, spectral library usage, mixture analysis, and feature extraction. High speed spectral signature matching is performed by using a binary spectral encoding algorithm to separate and identify mineral components present in the scene. The same binary encoding allows automatic spectral clustering. Spectral data may be entered from a digitizing tablet, stored in a user library, compared to the master library containing mineral standards, and then displayed as a timesequence spectral movie. The output plots, histograms, and stretched histograms produced by SPAM can be sent to a lineprinter, stored as separate RGB disk files, or sent to a Quick Color Recorder. SPAM is written in C for interactive execution and is available for two different

  16. Expressiveness considerations of XML signatures

    DEFF Research Database (Denmark)

    Jensen, Meiko; Meyer, Christopher

    2011-01-01

    more and more challenging. In this paper, we investigate this issue, describing how an attacker can still interfere with Web Services communication even in the presence of XML Signatures. Additionally, we discuss the interrelation of XML Signatures and XML Encryption, focussing on their security......XML Signatures are used to protect XML-based Web Service communication against a broad range of attacks related to man-in-the-middle scenarios. However, due to the complexity of the Web Services specification landscape, the task of applying XML Signatures in a robust and reliable manner becomes...

  17. Expressiveness considerations of XML signatures

    DEFF Research Database (Denmark)

    Jensen, Meiko; Meyer, Christopher

    2011-01-01

    XML Signatures are used to protect XML-based Web Service communication against a broad range of attacks related to man-in-the-middle scenarios. However, due to the complexity of the Web Services specification landscape, the task of applying XML Signatures in a robust and reliable manner becomes...... more and more challenging. In this paper, we investigate this issue, describing how an attacker can still interfere with Web Services communication even in the presence of XML Signatures. Additionally, we discuss the interrelation of XML Signatures and XML Encryption, focussing on their security...

  18. Set signatures and their applications

    Institute of Scientific and Technical Information of China (English)

    WU ChuanKun

    2009-01-01

    There are many constraints In the use of digital signatures. This paper proposes a new way of using digital signatures with some restrictions, i.e. set signatures. It works in such a way that when the signing algorithm Is given, one can use it to create a valid signature on a message if and only if the message belongs to a pre-defined set, and given the information about the signing algorithm, It is computationally Infeasible to create valid signatures on any other arbitrary messages outside of the set. This special property enables the signing algorithm to be made public, which seems to contradict with the traditional signature where a private key Is needed, which must be kept secret. What makes the problem challenging is that the signing algorithm does not reveal the secret signing key, and hence forging normal signatures for arbitrary messages is computationaUy Infeasible. In many cases, the signing algorithm does not reveal the elements in the authorized set. As an application of the new concept, set signatures for intelligent mobile agents committing "smaller than" condition Is studied, which shows the applicability of set signatures on small sets.

  19. Spectral triples and differential calculi related to the Kronecker foliation

    Science.gov (United States)

    Matthes, R.; Richter, O.; Rudolph, G.

    2003-04-01

    Following the ideas of Connes and Moscovici, we describe two spectral triples related to the Kronecker foliation, whose generalized Dirac operators are related to first and second order signature operators. We also consider the corresponding differential calculi Ω D, which are drastically different in the two cases. For the second order signature operator we calculate the Chern character of the spectral triple and the Dixmier trace of certain powers of its Dirac operator. As a side-remark, we give a description of a known calculus on the two-dimensional noncommutative torus in terms of generators and relations.

  20. Special Nuclear Material Gamma-Ray Signatures for Reachback Analysts

    Energy Technology Data Exchange (ETDEWEB)

    Karpius, Peter Joseph [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Myers, Steven Charles [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-08-29

    These are slides on special nuclear material gamma-ray signatures for reachback analysts for an LSS Spectroscopy course. The closing thoughts for this presentation are the following: SNM materials have definite spectral signatures that should be readily recognizable to analysts in both bare and shielded configurations. One can estimate burnup of plutonium using certain pairs of peaks that are a few keV apart. In most cases, one cannot reliably estimate uranium enrichment in an analogous way to the estimation of plutonium burnup. The origin of the most intense peaks from some SNM items may be indirect and from ‘associated nuclides.' Indirect SNM signatures sometimes have commonalities with the natural gamma-ray background.

  1. Are leaf chemistry signatures preserved at the canopy level?

    Energy Technology Data Exchange (ETDEWEB)

    Borel, C.C.; Gerstl, S.A.W.

    1994-05-01

    Imaging spectrometers have the potential to be very useful in remote sensing of canopy chemistry constituents such as nitrogen and lignin. In this study under the HIRIS project the question of how leaf chemical composition which is reflected in leaf spectral features in the reflectance and transmittance is affected by canopy architecture was investigated. Several plants were modeled with high fidelity and a radiosity model was used to compute the canopy spectral signature over the visible and near infrared. We found that chemical constituent specific signatures such as absorptions are preserved and in the case of low absorption are actually enhanced. For moderately dense canopies the amount of a constituent depends also on the total leaf area.

  2. Forward-Secure Multisignature, Threshold Signature and Blind Signature Schemes

    Directory of Open Access Journals (Sweden)

    Jia Yu

    2010-06-01

    Full Text Available Forward-secure signatures are proposed to tackle the key exposure problem, in which the security of all signatures prior to key leakage is still kept even if the secret key leaks. In this paper, we construct two forward-secure multisignature schemes, one forward-secure threshold signature scheme, and one forward-secure blind signature scheme. Our constructions are based on the recently proposed forward-secure signature scheme from bilinear maps in [11]. Our constructions are very efficient and useful thanks to the elegant structure of the base scheme. Such schemes play an important role in many electronic applications such as cryptographic election systems, digital cash schemes, and e-cheques.

  3. Nonlinear spectral imaging of biological tissues

    Science.gov (United States)

    Palero, J. A.

    2007-07-01

    The work presented in this thesis demonstrates live high resolution 3D imaging of tissue in its native state and environment. The nonlinear interaction between focussed femtosecond light pulses and the biological tissue results in the emission of natural autofluorescence and second-harmonic signal. Because biological intrinsic emission is generally very weak and extends from the ultraviolet to the visible spectral range, a broad-spectral range and high sensitivity 3D spectral imaging system is developed. Imaging the spectral characteristics of the biological intrinsic emission reveals the structure and biochemistry of the cells and extra-cellular components. By using different methods in visualizing the spectral images, discrimination between different tissue structures is achieved without the use of any stain or fluorescent label. For instance, RGB real color spectral images of the intrinsic emission of mouse skin tissues show blue cells, green hair follicles, and purple collagen fibers. The color signature of each tissue component is directly related to its characteristic emission spectrum. The results of this study show that skin tissue nonlinear intrinsic emission is mainly due to the autofluorescence of reduced nicotinamide adenine dinucleotide (phosphate), flavins, keratin, melanin, phospholipids, elastin and collagen and nonlinear Raman scattering and second-harmonic generation in Type I collagen. In vivo time-lapse spectral imaging is implemented to study metabolic changes in epidermal cells in tissues. Optical scattering in tissues, a key factor in determining the maximum achievable imaging depth, is also investigated in this work.

  4. Towards a Standard Plant Species Spectral Library Protocol for Vegetation Mapping: A Case Study in the Shrubland of Doñana National Park

    Directory of Open Access Journals (Sweden)

    Marcos Jiménez

    2015-11-01

    Full Text Available One of the main applications of field spectroscopy is the generation of spectral libraries of Earth’s surfaces or materials to support mapping activities using imaging spectroscopy. To enhance the reliability of these libraries, spectral signature acquisition should be carried out following standard procedures and controlled experimental approaches. This paper presents a standard protocol for the creation of a spectral library for plant species. The protocol is based on characterizing the reflectance spectral response of different species in the spatiotemporal domain, by accounting for intra-species variation and inter-species similarity. A practical case study was conducted on the shrubland located in Doñana National Park (SW Spain. Spectral libraries of the five dominant shrub species were built (Erica scoparia, Halimium halimifolium, Ulex australis, Rosmarinus officinalis, and Stauracanthus genistoides. An estimation was made of the separability between species: on one hand, the Student’s t-test evaluates significant intra-species variability (p < 0.05 and on the other hand, spectral similarity value (SSV and spectral angle mapper (SAM algorithms obtain significant separability values for dominant species, although it was not possible to discriminate the legume species Ulex australis and Stauracanthus genistoides.

  5. Spectral Decomposition Algorithm (SDA)

    Data.gov (United States)

    National Aeronautics and Space Administration — Spectral Decomposition Algorithm (SDA) is an unsupervised feature extraction technique similar to PCA that was developed to better distinguish spectral features in...

  6. A Secure Threshold Group Signature Scheme

    Institute of Scientific and Technical Information of China (English)

    Wang Xiaoming; Fu Fangwei

    2003-01-01

    The threshold group signature is an important kind of signature. So far, many threshold group signature schemes have been proposed, but most of them suffer from conspiracy attack and are insecure. In this paper, a secure threshold group signature scheme is proposed. It can not only satisfy the properties of the threshold group signature, but also withstand the conspiracy attack

  7. Signatures de l'invisible

    CERN Multimedia

    CERN Press Office. Geneva

    2000-01-01

    "Signatures of the Invisible" is an unique collaboration between contemporary artists and contemporary physicists which has the potential to help redefine the relationship between science and art. "Signatures of the Invisible" is jointly organised by the London Institute - the world's largest college of art and design and CERN*, the world's leading particle physics laboratory. 12 leading visual artists:

  8. IAR signatures in the ionosphere: Modeling and observations at the Chibis-M microsatellite

    Science.gov (United States)

    Pilipenko, V.; Dudkin, D.; Fedorov, E.; Korepanov, V.; Klimov, S.

    2017-02-01

    A peculiar feature of geomagnetic variations at middle/low latitudes in the ULF band, just below the fundamental tone of the Schumann resonance, is the occurrence of a multi-band spectral resonant structure, observed by high-sensitivity induction magnetometers during nighttime. The occurrence of such spectral structure was commonly attributed to the Ionospheric Alfvén Resonator (IAR) in the upper ionosphere. Rather surprisingly, while ground observations of the IAR are ubiquitous, there are practically no reports on the IAR signatures from space missions. According to the new paradigm, the multi-band spectral structure excited by a lightning discharge is in fact produced by a regular sequence of an original pulse from a stroke and echo-pulses reflected from the IAR upper boundary. Upon the interaction of initial lightning-generated pulse with the anisotropic lower ionosphere, it partially penetrates into the ionosphere, travels up the ionosphere as an Alfvén pulse, and reflects back from the upper IAR boundary. The superposition of the initial pulse and echo-pulses produces spectra with multiple spectral peaks. Our modeling of Alfvénic pulse propagation in a system with the altitude profile of Alfven velocity modeling the realistic ionosphere has shown that IAR spectral signatures are to be evident only on the ground and above the IAR. Inside the IAR, the superposition of upward and downward propagating pulses produces a more complicated spectral pattern and the IAR spectral signatures deteriorate. We have used electric field data from the low-orbit Chibis-M microsatellite to search for IAR signatures in the ionosphere. We found evidence that the multi-band structure revealed by spectral analysis in the frequency range of interest is indeed the result of a sequence of lightning-produced pulses. According to the proposed conception it seems possible to comprehend why the IAR signatures are less evident in the ionosphere than on the ground.

  9. Identification of Chemical Attribution Signatures of Fentanyl Syntheses Using Multivariate Statistical Analysis of Orthogonal Analytical Data

    Energy Technology Data Exchange (ETDEWEB)

    Mayer, B. P. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Mew, D. A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); DeHope, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Spackman, P. E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Williams, A. M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-09-24

    Attribution of the origin of an illicit drug relies on identification of compounds indicative of its clandestine production and is a key component of many modern forensic investigations. The results of these studies can yield detailed information on method of manufacture, starting material source, and final product - all critical forensic evidence. In the present work, chemical attribution signatures (CAS) associated with the synthesis of the analgesic fentanyl, N-(1-phenylethylpiperidin-4-yl)-N-phenylpropanamide, were investigated. Six synthesis methods, all previously published fentanyl synthetic routes or hybrid versions thereof, were studied in an effort to identify and classify route-specific signatures. 160 distinct compounds and inorganic species were identified using gas and liquid chromatographies combined with mass spectrometric methods (GC-MS and LCMS/ MS-TOF) in conjunction with inductively coupled plasma mass spectrometry (ICPMS). The complexity of the resultant data matrix urged the use of multivariate statistical analysis. Using partial least squares discriminant analysis (PLS-DA), 87 route-specific CAS were classified and a statistical model capable of predicting the method of fentanyl synthesis was validated and tested against CAS profiles from crude fentanyl products deposited and later extracted from two operationally relevant surfaces: stainless steel and vinyl tile. This work provides the most detailed fentanyl CAS investigation to date by using orthogonal mass spectral data to identify CAS of forensic significance for illicit drug detection, profiling, and attribution.

  10. Coupling Modified Linear Spectral Mixture Analysis and Soil Conservation Service Curve Number (SCS-CN Models to Simulate Surface Runoff: Application to the Main Urban Area of Guangzhou, China

    Directory of Open Access Journals (Sweden)

    Jianhui Xu

    2016-11-01

    Full Text Available Land surface characteristics, including soil type, terrain slope, and antecedent soil moisture, have significant impacts on surface runoff during heavy precipitation in highly urbanized areas. In this study, a Linear Spectral Mixture Analysis (LSMA method is modified to extract high-precision impervious surface, vegetation, and soil fractions. In the modified LSMA method, the representative endmembers are first selected by combining a high-resolution image from Google Earth; the unmixing results of the LSMA are then post-processed to reduce errors of misclassification with Normalized Difference Built-up Index (NDBI and Normalized Difference Vegetation Index (NDVI. The modified LSMA is applied to the Landsat 8 Operational Land Imager (OLI image from 18 October 2015 of the main urban area of Guangzhou city. The experimental result indicates that the modified LSMA shows improved extraction performance compared with the conventional LSMA, as it can significantly reduce the bias and root-mean-square error (RMSE. The improved impervious surface, vegetation, and soil fractions are used to calculate the composite curve number (CN for each pixel according to the Soil Conservation Service curve number (SCS-CN model. The composite CN is then adjusted with regional data of the terrain slope and total 5-day antecedent precipitation. Finally, the surface runoff is simulated with the SCS-CN model by combining the adjusted CN and real precipitation data at 1 p.m., 4 May 2015.

  11. Materials and Surface Processes at Gale Crater and the Moons of Mars Derived from High Spatial and Spectral Resolution Orbital Datasets

    Science.gov (United States)

    Fraeman, Abigail Ann

    This thesis is a collection of studies that use orbital remote sensing data to investigate the composition and geologic histories of Mars' moons, Phobos and Deimos, and Mt. Sharp, the destination for the Curiosity Mars rover. A final chapter focuses on Curiosity data and terrestrial analog studies to supplement orbital predictions about Mt. Sharp. Disk-resolved hyperspectral observations of Phobos acquired at a range of lighting and viewing geometries are fit with a Hapke photometric function to solve for the single particle phase function and single scattering albedos of Phobos and also disk-resolved hyperspectral observations of Deimos. Fe2+ electronic absorptions diagnostic of olivine and pyroxene are not detected. A broad absorption centered on 0.65 microm within the red spectral units of both moons is seen, and this feature is also evident in telescopic, Pathfinder, and Phobos-2 observations of Phobos. A 2.8 μm metal-OH combination absorption on both moons is also detected, and this absorption is shallower in the Phobos blue unit than in the Phobos red unit and Deimos. The strength, position, and shape of both absorptions are similar to features seen on low-albedo primitive asteroids. Two end-member hypotheses could explain these spectral features: the presence of highly desiccated Fe-phyllosilicate minerals indigenous to the bodies, or Rayleigh scattering and absorption of small iron particles formed by exogenic space weathering processing, coupled with implantation of H from solar wind. Phobos' and Deimos' low reflectances, lack of mafic absorption features, and red spectral slopes are incompatible with even highly space weathered chondritic or basaltic compositions. These results, coupled with similarities to laboratory spectra of Tagish Lake (possible D-type asteroid analog) and CM carbonaceous chondrite meteorites, show that Phobos and Deimos have primitive compositions. If the moons formed in situ rather than by capture of primitive bodies, primitive

  12. (In,Ga,Al)P–GaP laser diodes grown on high-index GaAs surfaces emitting in the green, yellow and bright red spectral range

    Science.gov (United States)

    Ledentsov, N. N.; Shchukin, V. A.; Shernyakov, Yu M.; Kulagina, M. M.; Payusov, A. S.; Gordeev, N. Yu; Maximov, M. V.; Cherkashin, N. A.

    2017-02-01

    We report on low threshold current density (region. Extended waveguide concept results in a vertical beam divergence with a full width at half maximum of 15° for (611)A substrates. The lasing at the wavelength of 569 nm is realized at 85 K. In an orange–red laser diode structure low threshold current density (190 A cm‑2) in the orange spectral range (598 nm) is realized at 85 K. The latter devices demonstrated room temperature lasing at 628 nm at ∼2 kA cm‑2 and a total power above 3 W. The red laser diodes grown on (211)A substrates demonstrated a far field characteristic for vertically multimode lasing indicating a lower optical confinement factor for the fundamental mode as compared to the devices grown on (611)A. However, as expected from previous research, the temperature stability of the threshold current and the wavelength stability were significantly higher for (211)A-grown structures.

  13. Active spectral imaging nondestructive evaluation (SINDE) camera

    Energy Technology Data Exchange (ETDEWEB)

    Simova, E.; Rochefort, P.A., E-mail: eli.simova@cnl.ca [Canadian Nuclear Laboratories, Chalk River, Ontario (Canada)

    2016-06-15

    A proof-of-concept video camera for active spectral imaging nondestructive evaluation has been demonstrated. An active multispectral imaging technique has been implemented in the visible and near infrared by using light emitting diodes with wavelengths spanning from 400 to 970 nm. This shows how the camera can be used in nondestructive evaluation to inspect surfaces and spectrally identify materials and corrosion. (author)

  14. Spectral triangulation: a 3D method for locating single-walled carbon nanotubes in vivo.

    Science.gov (United States)

    Lin, Ching-Wei; Bachilo, Sergei M; Vu, Michael; Beckingham, Kathleen M; Bruce Weisman, R

    2016-05-21

    Nanomaterials with luminescence in the short-wave infrared (SWIR) region are of special interest for biological research and medical diagnostics because of favorable tissue transparency and low autofluorescence backgrounds in that region. Single-walled carbon nanotubes (SWCNTs) show well-known sharp SWIR spectral signatures and therefore have potential for noninvasive detection and imaging of cancer tumours, when linked to selective targeting agents such as antibodies. However, such applications face the challenge of sensitively detecting and localizing the source of SWIR emission from inside tissues. A new method, called spectral triangulation, is presented for three dimensional (3D) localization using sparse optical measurements made at the specimen surface. Structurally unsorted SWCNT samples emitting over a range of wavelengths are excited inside tissue phantoms by an LED matrix. The resulting SWIR emission is sampled at points on the surface by a scanning fibre optic probe leading to an InGaAs spectrometer or a spectrally filtered InGaAs avalanche photodiode detector. Because of water absorption, attenuation of the SWCNT fluorescence in tissues is strongly wavelength-dependent. We therefore gauge the SWCNT-probe distance by analysing differential changes in the measured SWCNT emission spectra. SWCNT fluorescence can be clearly detected through at least 20 mm of tissue phantom, and the 3D locations of embedded SWCNT test samples are found with sub-millimeter accuracy at depths up to 10 mm. Our method can also distinguish and locate two embedded SWCNT sources at distinct positions.

  15. BIM for existing facilities: feasibility of spectral image integration to 3D point cloud data

    Directory of Open Access Journals (Sweden)

    Amano Kinjiro

    2016-01-01

    Full Text Available Accurate geometrical and spatial information of the built environment can be accurately acquired and the resulting 3D point cloud data is required to be processed to construct the digital model, Building Information Modelling (BIM for existing facilities. Point cloud by laser scanning over the buildings and facilities has been commonly used, but the data requires external information so that any objects and materials can be correctly identified and classified. A number of advanced data processing methods have been developed, such as the use of colour information to attach semantic information. However, the accuracy of colour information depends largely on the scene environment where the image is acquired. The limited number of spectral channels on conventional RGB camera often fails to extract important information about surface material, despite spectral surface reflectance can represent a signature of the material. Hyperspectral imaging can, instead, provide precise representation of spatial and spectral information. By implementing such information to 3D point cloud, the efficiency of material detection and classification in BIM should be significantly improved. In this work, the feasibility of the image integration and discuss practical difficulties in the development.

  16. Structural origin of Si-2p core-level shifts from Si(100)-c[4x2] surface: A spectral x-ray photoelectron diffraction study

    Energy Technology Data Exchange (ETDEWEB)

    Chen, X.; Tonner, B.P. [Univ. of Wisconsin, Milwaukee, WI (United States); Denlinger, J. [Univ. of Wisconsin, Milwaukee, WI (United States)][Ernest Orlando Lawrence Berkeley National Lab., CA (United States)] [and others

    1997-04-01

    The authors have performed angle-resolved x-ray photoelectron diffraction (XPD) from a Si(100)-c(4x2) surface to study the structural origin of Si-2p core-level shifts. In the experiment, the highly resolved surface Si-2p core-level spectra were measured as a fine grid of hemisphere and photon energies, using the SpectroMicroscopy Facility {open_quotes}ultraESCA{close_quotes} instrument. By carefully decomposing the spectra into several surface peaks, the authors are able to obtain surface-atom resolved XPD patterns. Using a multiple scattering analysis, they derived a detailed atomic model for the Si(100)-c(4x2) surface. In this model, the asymmetric dimers were found tilted by 11.5 plus/minus 2.0 degrees with bond length of 2.32 plus/minus 0.05{angstrom}. By matching model XPD patterns to experiment, the authors can identify which atoms in the reconstructed surface are responsible for specific photoemission lines in the 2p spectrum.

  17. Signatures of AGN feedback

    Science.gov (United States)

    Wylezalek, Dominika; Zakamska, Nadia L.; MaNGA-GMOS Team

    2017-01-01

    Feedback from actively accreting SMBHs (Active Galactic Nuclei, AGN) is now widely considered to be the main driver in regulating the growth of massive galaxies. Observational proof for this scenario has, however, been hard to come by. Many attempts at finding a conclusive observational proof that AGN may be able to quench star formation and regulate the host galaxies' growth have shown that this problem is highly complex.I will present results from several projects that focus on understanding the power, reach and impact of feedback processes exerted by AGN. I will describe recent efforts in our group of relating feedback signatures to the specific star formation rate in their host galaxies, where our results are consistent with the AGN having a `negative' impact through feedback on the galaxies' star formation history (Wylezalek+2016a,b). Furthermore, I will show that powerful AGN-driven winds can be easily hidden and not be apparent in the integrated spectrum of the galaxy. This implies that large IFU surveys, such as the SDSS-IV MaNGA survey, might uncover many previously unknown AGN and outflows that are potentially very relevant for understanding the role of AGN in galaxy evolution (Wylezalek+2016c)!

  18. Quantum Spectral Symmetries

    Science.gov (United States)

    Hamhalter, Jan; Turilova, Ekaterina

    2017-02-01

    Quantum symmetries of spectral lattices are studied. Basic properties of spectral order on A W ∗-algebras are summarized. Connection between projection and spectral automorphisms is clarified by showing that, under mild conditions, any spectral automorphism is a composition of function calculus and Jordan ∗-automorphism. Complete description of quantum spectral symmetries on Type I and Type II A W ∗-factors are completely described.

  19. Characterizing riverbed sediment using high-frequency acoustics: 2. Scattering signatures of Colorado River bed sediment in Marble and Grand Canyons

    Science.gov (United States)

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

    2014-12-01

    In this, the second of a pair of papers on the statistical signatures of riverbed sediment in high-frequency acoustic backscatter, spatially explicit maps of the stochastic geometries (length and amplitude scales) of backscatter are related to patches of riverbed surfaces composed of known sediment types, as determined by georeferenced underwater video observations. Statistics of backscatter magnitudes alone are found to be poor discriminators between sediment types. However, the variance of the power spectrum and the intercept and slope from a power law spectral form (termed the spectral strength and exponent, respectively) successfully discriminate between sediment types. A decision tree approach was able to classify spatially heterogeneous patches of homogeneous sands, gravels (and sand-gravel mixtures), and cobbles/boulders with 95, 88, and 91% accuracy, respectively. Application to sites outside the calibration and surveys made at calibration sites at different times were plausible based on observations from underwater video. Analysis of decision trees built with different training data sets suggested that the spectral exponent was consistently the most important variable in the classification. In the absence of theory concerning how spatially variable sediment surfaces scatter high-frequency sound, the primary advantage of this data-driven approach to classify bed sediment over alternatives is that spectral methods have well-understood properties and make no assumptions about the distributional form of the fluctuating component of backscatter over small spatial scales.

  20. Characterizing riverbed sediment using high-frequency acoustics 2: scattering signatures of Colorado River bed sediment in Marble and Grand Canyons

    Science.gov (United States)

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

    2014-01-01

    In this, the second of a pair of papers on the statistical signatures of riverbed sediment in high-frequency acoustic backscatter, spatially explicit maps of the stochastic geometries (length- and amplitude-scales) of backscatter are related to patches of riverbed surfaces composed of known sediment types, as determined by geo-referenced underwater video observations. Statistics of backscatter magnitudes alone are found to be poor discriminators between sediment types. However, the variance of the power spectrum, and the intercept and slope from a power-law spectral form (termed the spectral strength and exponent, respectively) successfully discriminate between sediment types. A decision-tree approach was able to classify spatially heterogeneous patches of homogeneous sands, gravels (and sand-gravel mixtures), and cobbles/boulders with 95, 88, and 91% accuracy, respectively. Application to sites outside the calibration, and surveys made at calibration sites at different times, were plausible based on observations from underwater video. Analysis of decision trees built with different training data sets suggested that the spectral exponent was consistently the most important variable in the classification. In the absence of theory concerning how spatially variable sediment surfaces scatter high-frequency sound, the primary advantage of this data-driven approach to classify bed sediment over alternatives is that spectral methods have well understood properties and make no assumptions about the distributional form of the fluctuating component of backscatter over small spatial scales.

  1. Analysis of Cross-Seasonal Spectral Response from Kettle Holes: Application of Remote Sensing Techniques for Chlorophyll Estimation

    Directory of Open Access Journals (Sweden)

    Bernd Lennartz

    2012-11-01

    Full Text Available Kettle holes, small inland water bodies usually less than 1 ha in size, are subjected to pollution, drainage, and structural alteration by intensive land use practices. This study presents the analysis of spectral signatures from kettle holes based on in situ water sampling and reflectance measurements in application for chlorophyll estimation. Water samples and surface reflectance from kettle holes were collected from 6 ponds in 15 field campaigns (5 in 2007 and 10 in 2008, resulting in a total of 80 spectral datasets. We assessed the existing semi-empirical algorithms to determine chlorophyll content for different types of kettle holes using seasonal and cross-seasonal volume reflectance and derivative spectra. Based on this analysis and optical properties of water leaving reflectance from kettle holes, the following typology of the remote signal interpretation was proposed: Submerged vegetation, Phytoplankton dominated and Mixed type.

  2. Secure mediated certificateless signature scheme

    Institute of Scientific and Technical Information of China (English)

    YANG Chen; MA Wen-ping; WANG Xin-mei

    2007-01-01

    Ju et al proposed a certificateless signature scheme with instantaneous revocation by introducing security mediator (SEM) mechanism. This article presents a detailed cryptoanalysis of this scheme and shows that, in their proposed scheme, once a valid signature has been produced, the signer can recover his private key information and the instantaneous revocation property will be damaged. Furthermore, an improved mediated signature scheme, which can eliminate these disadvantages, is proposed, and security proof of the improved scheme under elliptic curve factorization problem (ECFP) assumption and bilinear computational diffie-hellman problem (BCDH) assumption is also proposed.

  3. SIGNATURES OF LONG-LIVED SPIRAL PATTERNS

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Garcia, Eric E. [Instituto Nacional de Astrofisica, Optica y Electronica (INAOE), Aptdo. Postal 51 y 216, 72000 Puebla, Pue. (Mexico); Gonzalez-Lopezlira, Rosa A., E-mail: ericmartinez@inaoep.mx, E-mail: martinez@astro.unam.mx, E-mail: r.gonzalez@crya.unam.mx [Centro de Radioastronomia y Astrofisica, UNAM, Campus Morelia, Michoacan, C.P. 58089 (Mexico)

    2013-03-10

    Azimuthal age/color gradients across spiral arms are a signature of long-lived spirals. From a sample of 19 normal (or weakly barred) spirals where we have previously found azimuthal age/color gradient candidates, 13 objects were further selected if a two-armed grand-design pattern survived in a surface density stellar mass map. Mass maps were obtained from optical and near-infrared imaging, by comparison with a Monte Carlo library of stellar population synthesis models that allowed us to obtain the mass-to-light ratio in the J band, (M/L){sub J}, as a function of (g - i) versus (i - J) color. The selected spirals were analyzed with Fourier methods in search of other signatures of long-lived modes related to the gradients, such as the gradient divergence toward corotation, and the behavior of the phase angle of the two-armed spiral in different wavebands, as expected from theory. The results show additional signatures of long-lived spirals in at least 50% of the objects.

  4. On psychoanalytic supervision as signature pedagogy.

    Science.gov (United States)

    Watkins, C Edward

    2014-04-01

    What is signature pedagogy in psychoanalytic education? This paper examines that question, considering why psychoanalytic supervision best deserves that designation. In focusing on supervision as signature pedagogy, I accentuate its role in building psychoanalytic habits of mind, habits of hand, and habits of heart, and transforming theory and self-knowledge into practical product. Other facets of supervision as signature pedagogy addressed in this paper include its features of engagement, uncertainty, formation, and pervasiveness, as well as levels of surface, deep, and implicit structure. Epistemological, ontological, and axiological in nature, psychoanalytic supervision engages trainees in learning to do, think, and value what psychoanalytic practitioners in the field do, think, and value: It is, most fundamentally, professional preparation for competent, "good work." In this paper, effort is made to shine a light on and celebrate the pivotal role of supervision in "making" or developing budding psychoanalysts and psychoanalytic psychotherapists. Now over a century old, psychoanalytic supervision remains unparalleled in (1) connecting and integrating conceptualization and practice, (2) transforming psychoanalytic theory and self-knowledge into an informed analyzing instrument, and (3) teaching, transmitting, and perpetuating the traditions, practice, and culture of psychoanalytic treatment.

  5. Spectral Properties of Chlorides and Other Oxidized Chlorine Compounds in Relation to Europa

    Science.gov (United States)

    Hanley, Jennifer; Dalton, J. B., III

    2010-10-01

    Galileo's Near-Infrared Mapping Spectrometer (NIMS) has revealed the surface of Europa to be mostly water ice. The non-icy spectra have been compared to those of various hydrated minerals, suggesting that the non-ice material has a heavily hydrated salt component. However, many relevant laboratory spectra are still not available, especially at the low temperatures and pressures of Europa. In particular, chlorides are predicted to exist in the interior, and if the non-ice material is of an endogenic source, hydrated chlorides might be present on the surface. Oxidation of chlorides would result in chlorates (ClO3-) and/or perchlorates (ClO4-) as well. Both chlorates and perchlorates would lower the freezing point of water significantly (down to 205 K in the case of Mg(ClO4)2), adding new constraints to the arguments for a liquid layer below the surface. Using an environmental chamber to create the relevant pressures and temperatures of Europa, we have acquired new spectra of some of these hydrated salts, specifically MgCl2, Mg(ClO3)2, NaClO4 and Mg(ClO4)2. These materials exhibit spectral features similar to those seen on NIMS observations of Europa's non-icy terrains. We will compare these spectra to those of water ice, hydrated sulfates, and the data. Preliminary analysis suggests that chlorate hydrates may contribute to the spectral signature of Europa's surface deposits.

  6. An Evaluation of Total Solar Reflectance and Spectral Band Ratioing Techniques for Estimating Soil Water Content

    Science.gov (United States)

    Reginato, R. J.; Vedder, J. F.; Idso, S. B.; Jackson, R. D.; Blanchard, M. B.; Goettelman, R.

    1977-01-01

    For several days in March of 1975, reflected solar radiation measurements were obtained from smooth and rough surfaces of wet, drying, and continually dry Avondale loam at Phoenix, Arizona, with pyranometers located 50 cm above the ground surface and a multispectral scanner flown at a 300-m height. The simple summation of the different band radiances measured by the multispectral scanner proved equally as good as the pyranometer data for estimating surface soil water content if the multispectral scanner data were standardized with respect to the intensity of incoming solar radiation or the reflected radiance from a reference surface, such as the continually dry soil. Without this means of standardization, multispectral scanner data are most useful in a spectral band ratioing context. Our results indicated that, for the bands used, no significant information on soil water content could be obtained by band ratioing. Thus the variability in soil water content should insignificantly affect soil-type discrimination based on identification of type-specific spectral signatures. Therefore remote sensing, conducted in the 0.4- to 1.0-micron wavelength region of the solar spectrum, would seem to be much More suited to identifying crop and soil types than to estimating of soil water content.

  7. A new adaptive method to filter terrestrial laser scanner point clouds using morphological filters and spectral information to conserve surface micro-topography

    Science.gov (United States)

    Rodríguez-Caballero, E.; Afana, A.; Chamizo, S.; Solé-Benet, A.; Canton, Y.

    2016-07-01

    Terrestrial laser scanning (TLS), widely known as light detection and ranging (LiDAR) technology, is increasingly used to provide highly detailed digital terrain models (DTM) with millimetric precision and accuracy. In order to generate a DTM, TLS data has to be filtered from undesired spurious objects, such as vegetation, artificial structures, etc., Early filtering techniques, successfully applied to airborne laser scanning (ALS), fail when applied to TLS data, as they heavily smooth the terrain surface and do not retain their real morphology. In this article, we present a new methodology for filtering TLS data based on the geometric and radiometric properties of the scanned surfaces. This methodology was built on previous morphological filters that select the minimum point height within a sliding window as the real surface. However, contrary to those methods, which use a fixed window size, the new methodology operates under different spatial scales represented by different window sizes, and can be adapted to different types and sizes of plants. This methodology has been applied to two study areas of differing vegetation type and density. The accuracy of the final DTMs was improved by ∼30% under dense canopy plants and over ∼40% on the open spaces between plants, where other methodologies drastically underestimated the real surface heights. This resulted in more accurate representation of the soil surface and microtopography than up-to-date techniques, eventually having strong implications in hydrological and geomorphological studies.

  8. Application of the Frequency Spectrum to Spectral Similarity Measures

    Directory of Open Access Journals (Sweden)

    Ke Wang

    2016-04-01

    Full Text Available Several frequency-based spectral similarity measures, derived from commonly-used ones, are developed for hyperspectral image classification based on the frequency domain. Since the frequency spectrum (magnitude spectrum of the original signature for each pixel from hyperspectral data can clearly reflect the spectral features of different types of land covers, we replace the original spectral signature with its frequency spectrum for calculating the existing spectral similarity measure. The frequency spectrum is symmetrical around the direct current (DC component; thus, we take one-half of the frequency spectrum from the DC component to the highest frequency component as the input signature. Furthermore, considering the fact that the low frequencies include most of the frequency energy, we can optimize the classification result by choosing the ratio of the frequency spectrum (from the DC component to the highest frequency component involved in the calculation. In our paper, the frequency-based measures based on the spectral gradient angle (SAM, spectral information divergence (SID, spectral correlation mapper (SCM, Euclidean distance (ED, normalized Euclidean distance (NED and SID × sin(SAM (SsS measures are called the F-SAM, F-SID, F-SCM, F-ED, F-NED and F-SsS, respectively. In the experiment, three commonly-used hyperspectral remote sensing images are employed as test data. The frequency-based measures proposed here are compared to the corresponding existing ones in terms of classification accuracy. The classification results by parameter optimization are also analyzed. The results show that, although not all frequency-based spectral similarity measures are better than the original ones, some frequency-based measures, such as the F-SsS and F-SID, exhibit a relatively better performance and have more robust applications than the other spectral similarity measures.

  9. Spectroscopic Signatures Related to a Sunquake

    CERN Document Server

    Matthews, Sarah A; Zharkov, Sergei; Green, Lucie M

    2015-01-01

    The presence of flare related acoustic emission (sunquakes) in some flares represents a severe challenge to our current understanding of flare energy transport processes. We present a comparison of new spectral observations from Hinode's EUV imaging Spectrometer (EIS) and the Interface Region Imaging Spectrograph (IRIS) of the atmosphere above a sunquake, and compare them to the spectra observed in a part of the flaring region with no acoustic signature. Evidence for the sunquake is determined using both time-distance and acoustic holography methods, and we find that, unlike many previous sunquake detections, the signal is rather dispersed, but that the time-distance and 6 and 7 mHz sources converge at the same spatial location. We also see some evidence for different evolution at different frequencies, with an earlier peak at 7 mHz than at 6 mHz. Using spectroscopic measurements we find that in this location at the time of the 7 mHz peak the spectral emission is significantly more intense, shows larger veloc...

  10. The Spectral Shift Function and Spectral Flow

    Science.gov (United States)

    Azamov, N. A.; Carey, A. L.; Sukochev, F. A.

    2007-11-01

    At the 1974 International Congress, I. M. Singer proposed that eta invariants and hence spectral flow should be thought of as the integral of a one form. In the intervening years this idea has lead to many interesting developments in the study of both eta invariants and spectral flow. Using ideas of [24] Singer’s proposal was brought to an advanced level in [16] where a very general formula for spectral flow as the integral of a one form was produced in the framework of noncommutative geometry. This formula can be used for computing spectral flow in a general semifinite von Neumann algebra as described and reviewed in [5]. In the present paper we take the analytic approach to spectral flow much further by giving a large family of formulae for spectral flow between a pair of unbounded self-adjoint operators D and D + V with D having compact resolvent belonging to a general semifinite von Neumann algebra {mathcal{N}} and the perturbation V in {mathcal{N}} . In noncommutative geometry terms we remove summability hypotheses. This level of generality is made possible by introducing a new idea from [3]. There it was observed that M. G. Krein’s spectral shift function (in certain restricted cases with V trace class) computes spectral flow. The present paper extends Krein’s theory to the setting of semifinite spectral triples where D has compact resolvent belonging to {mathcal{N}} and V is any bounded self-adjoint operator in {mathcal{N}} . We give a definition of the spectral shift function under these hypotheses and show that it computes spectral flow. This is made possible by the understanding discovered in the present paper of the interplay between spectral shift function theory and the analytic theory of spectral flow. It is this interplay that enables us to take Singer’s idea much further to create a large class of one forms whose integrals calculate spectral flow. These advances depend critically on a new approach to the calculus of functions of non

  11. Initial Semantics for Strengthened Signatures

    Directory of Open Access Journals (Sweden)

    André Hirschowitz

    2012-02-01

    Full Text Available We give a new general definition of arity, yielding the companion notions of signature and associated syntax. This setting is modular in the sense requested by Ghani and Uustalu: merging two extensions of syntax corresponds to building an amalgamated sum. These signatures are too general in the sense that we are not able to prove the existence of an associated syntax in this general context. So we have to select arities and signatures for which there exists the desired initial monad. For this, we follow a track opened by Matthes and Uustalu: we introduce a notion of strengthened arity and prove that the corresponding signatures have initial semantics (i.e. associated syntax. Our strengthened arities admit colimits, which allows the treatment of the λ-calculus with explicit substitution.

  12. Retail applications of signature verification

    Science.gov (United States)

    Zimmerman, Thomas G.; Russell, Gregory F.; Heilper, Andre; Smith, Barton A.; Hu, Jianying; Markman, Dmitry; Graham, Jon E.; Drews, Clemens

    2004-08-01

    The dramatic rise in identity theft, the ever pressing need to provide convenience in checkout services to attract and retain loyal customers, and the growing use of multi-function signature captures devices in the retail sector provides favorable conditions for the deployment of dynamic signature verification (DSV) in retail settings. We report on the development of a DSV system to meet the needs of the retail sector. We currently have a database of approximately 10,000 signatures collected from 600 subjects and forgers. Previous work at IBM on DSV has been merged and extended to achieve robust performance on pen position data available from commercial point of sale hardware, achieving equal error rates on skilled forgeries and authentic signatures of 1.5% to 4%.

  13. Initial Semantics for Strengthened Signatures

    CERN Document Server

    Hirschowitz, André; 10.4204/EPTCS.77.5

    2012-01-01

    We give a new general definition of arity, yielding the companion notions of signature and associated syntax. This setting is modular in the sense requested by Ghani and Uustalu: merging two extensions of syntax corresponds to building an amalgamated sum. These signatures are too general in the sense that we are not able to prove the existence of an associated syntax in this general context. So we have to select arities and signatures for which there exists the desired initial monad. For this, we follow a track opened by Matthes and Uustalu: we introduce a notion of strengthened arity and prove that the corresponding signatures have initial semantics (i.e. associated syntax). Our strengthened arities admit colimits, which allows the treatment of the \\lambda-calculus with explicit substitution.

  14. Growth, spectral, optical, thermal, surface analysis and third order nonlinear optical properties of an organic single crystal: 1-(2-Methyl-6-nitro-4-phenyl-3-quinolyl) ethanone.

    Science.gov (United States)

    Nirosha, M; Kalainathan, S; Sarveswari, S; Vijayakumar, V; Srikanth, A

    2015-02-25

    Single crystal of 1-(2-Methyl-6-nitro-4-phenyl-3-quinolyl) ethanone was grown using slow evaporation solution growth technique. Single crystal X-ray diffraction study reveals the lattice parameters of the grown crystal. The modes of vibration of different molecular groups present in 2M6NQE were identified by FTIR spectral analysis. Its optical behavior was examined through UV-vis-NIR absorption and PL emission spectrum. They signify that the crystal has transparency in the region between 383 and 1100 nm. The PL spectrum of the title compound shows green emission in the crystal. From the thermal analysis, 2M6NQE has found to be thermally stable up to 263°C, and the melting point of the material is 170°C. The estimations of third order non-linear optical properties like non-linear absorption coefficient (β), non-linear refractive index (n2) and susceptibility [χ(3)] were calculated using Z-scan technique. It has observed that, crystal exhibits reverse saturation absorption and self-defocusing performance. Etching study was carried out for the grown crystal using different solvents. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. The Broadband and Spectrally-Resolved H-band Eclipse of KELT-1b and the Role of Surface Gravity in Stratospheric Inversions in Hot Jupiters

    CERN Document Server

    Beatty, Thomas G; Pogge, Richard; Chung, Sun Mi; Bierlya, Allyson; Gaudi, B Scott; Latham, David W

    2016-01-01

    We present a high precision H-band emission spectrum of the transiting brown dwarf KELT-1b, which we spectrophotometrically observed during a single secondary eclipse using the LUCI1 multi-object spectrograph on the Large Binocular Telescope. Using a Gaussian-process regression model, we are able to clearly measure the broadband eclipse depth as Delta-H=1418+/-94ppm. We are also able to spectrally-resolve the H-band into five separate wavechannels and measure the eclipse spectrum of KELT-1b at R~50 with an average precision of +/-115ppm. We find that the day side has an average brightness temperature of 3250+/-50K, with significant variation as a function of wavelength. Based on our observations, and previous measurements of KELT-1b's eclipse at other wavelengths, we find that KELT-1b's day side appears identical to an isolated 3200K brown dwarf, and our modeling of the atmospheric emission shows a monotonically decreasing temperature-pressure profile. This is in contrast to hot Jupiters with similar day side...

  16. Resonance Raman Optical Activity and Surface Enhanced Resonance Raman Optical Activity analysis of Cytochrome C

    DEFF Research Database (Denmark)

    Johannessen, Christian; Abdali, Salim; White, Peter C.

    2007-01-01

    High quality Resonance Raman (RR) and resonance Raman Optical Activity (ROA) spectra of cytochrome c were obtained in order to perform full assignment of spectral features of the resonance ROA spectrum. The resonance ROA spectrum of cytochrome c revealed a distinct spectral signature pattern due...... to resonance enhanced skeletal porphyrin vibrations, more pronounced than any contribution from the protein back-bone. Combining the intrinsic resonance enhancement of cytochrome c with surface plasmon enhancement by colloidal silver particles, the Surface Enhanced Resonance Raman Scattering (SERRS) and Chiral...... Enhanced Raman Spectroscopy (ChERS) spectra of the protein were successfully obtained at very low concentration (as low as 1 µM). The assignment of spectral features was based on the information obtained from the RR and resonance ROA spectra. Excellent agreement between RR and SERRS spectra is reported...

  17. Contract Signature Using Quantum Information

    CERN Document Server

    De Sousa, P B M; Ramos, Rubens Viana; Sousa, Paulo Benicio Melo de

    2006-01-01

    This paper describes how to perform contract signature in a fair way using quantum information. The protocol proposed permits two partners, users of a communication network, to exchange their signatures with non-repudiation. For this, we assume that there is a trustable arbitrator, responsible for the authentication of the signers and that performs a central task in a quantum teleportation protocol of the XOR function between two classical bits.

  18. An arbitrated quantum signature scheme

    CERN Document Server

    Zeng, G; Zeng, Guihua; Keitel, Christoph H.

    2002-01-01

    The general principle for a quantum signature scheme is proposed and investigated based on ideas from classical signature schemes and quantum cryptography. The suggested algorithm is implemented by a symmetrical quantum key cryptosystem and Greenberger-Horne-Zeilinger (GHZ) triplet states and relies on the availability of an arbitrator. We can guarantee the unconditional security of the algorithm, mostly due to the correlation of the GHZ triplet states and the use of quantum one-time pads.

  19. Color signatures in Amorsolo paintings

    Science.gov (United States)

    Soriano, Maricor N.; Palomero, Cherry May; Cruz, Larry; Yambao, Clod Marlan Krister; Dado, Julie Mae; Salvador-Campaner, Janice May

    2010-02-01

    We present the results of a two-year project aimed at capturing quantifiable color signatures of oil paintings of Fernando Amorsolo, the Philippine's first National Artists. Color signatures are found by comparing CIE xy measurements of skin color in portraits and ground, sky and foliage in landscapes. The results are compared with results of visual examination and art historical data as well as works done by Amorsolo's contemporaries and mentors.

  20. Spectral modeling of Type II SNe

    Science.gov (United States)

    Dessart, Luc

    2015-08-01

    The red supergiant phase represents the final stage of evolution in the life of moderate mass (8-25Msun) massive stars. Hidden from view, the core changes considerably its structure, progressing through the advanced stages of nuclear burning, and eventually becomes degenerate. Upon reaching the Chandrasekhar mass, this Fe or ONeMg core collapses, leading to the formation of a proto neutron star. A type II supernova results if the shock that forms at core bounce, eventually wins over the envelope accretion and reaches the progenitor surface.The electromagnetic display of such core-collapse SNe starts with this shock breakout, and persists for months as the ejecta releases the energy deposited initially by the shock or continuously through radioactive decay. Over a timescale of weeks to months, the originally optically-thick ejecta thins out and turns nebular. SN radiation contains a wealth of information about the explosion physics (energy, explosive nucleosynthesis), the progenitor properties (structure and composition). Polarised radiation also offers signatures that can help constrain the morphology of the ejecta.In this talk, I will review the current status of type II SN spectral modelling, and emphasise that a proper solution requires a time dependent treatment of the radiative transfer problem. I will discuss the wealth of information that can be gleaned from spectra as well as light curves, from both the early times (photospheric phase) and late times (nebular phase). I will discuss the diversity of Type SNe properties and how they are related to the diversity of red supergiant stars from which they originate.SN radiation offers an alternate means of constraining the properties of red-supergiant stars. To wrap up, I will illustrate how SNe II-P can also be used as probes, for example to constrain the metallicity of their environment.

  1. Spectral element simulation of ultrafiltration

    DEFF Research Database (Denmark)

    Hansen, M.; Barker, Vincent A.; Hassager, Ole

    1998-01-01

    A spectral element method for simulating stationary 2-D ultrafiltration is presented. The mathematical model is comprised of the Navier-Stokes equations for the velocity field of the fluid and a transport equation for the concentration of the solute. In addition to the presence of the velocity...... vector in the transport equation, the system is coupled by the dependency of the fluid viscosity on the solute concentration and by a concentration-dependent boundary condition for the Navier-Stokes equations at the membrane surface. The spectral element discretization yields a nonlinear algebraic system....... The performance of the spectral element code when applied to several ultrafiltration problems is reported. (C) 1998 Elsevier Science Ltd. All rights reserved....

  2. The spectral optical properties and relative radiant heating contribution of dissolved and particulate matter in the surface waters across the Fram Strait

    DEFF Research Database (Denmark)

    Pavlov, A.K.; Granskog, M.A.; Stedmon, Colin

    The Fram Strait is the key region for exchange processes between Arctic Ocean and North Atlantic. With two major near-surface currents, the warm and salty West Spitsbergen Current and cold low-salinity East Greenland Current, its waters encompass two distinct oceanographic environments. During...

  3. Method based on artificial excitation of characteristic radiation by an electron beam for remote X-ray spectral elemental analysis of surface rocks on atmosphereless celestial bodies

    Science.gov (United States)

    Kolesnikov, E. K.

    2016-11-01

    This article, like our previous one [1], is devoted to advanced space technology concepts. It evaluates the potential for developing active systems to conduct a remote elemental analysis of surface rocks on an atmosphereless celestial body. The analysis is based on the spectrometry of characteristic X-rays (CXR) artificially excited in the surface soil layer. It has been proposed to use an electron beam injected from aboard a spacecraft orbiting the celestial body (or moving in a flyby trajectory) to excite the CXR elements contained in surface rocks. The focus is on specifying technical requirements to the parameters of payloads for a global mapping of the composition of lunar rocks from aboard of a low-orbiting lunar satellite. This article uses the results obtained in [2], our first study that shows the potential to develop an active system for a remote elemental analysis of lunar surface rocks using the above method. Although there has been interest in our research on the part of leading national academic institutions and space technology developers in the Soviet Union, the studies were discontinued because of the termination of the Soviet lunar program and the completion of the American Apollo program.

  4. The spectral optical properties and relative radiant heating contribution of dissolved and particulate matter in the surface waters across the Fram Strait

    DEFF Research Database (Denmark)

    Pavlov, A.K.; Granskog, M.A.; Stedmon, Colin

    The Fram Strait is the key region for exchange processes between Arctic Ocean and North Atlantic. With two major near-surface currents, the warm and salty West Spitsbergen Current and cold low-salinity East Greenland Current, its waters encompass two distinct oceanographic environments. During...