WorldWideScience

Sample records for pspc spectral reduction

  1. Streptococcus pneumoniae PspC Subgroup Prevalence in Invasive Disease and Differences in Contribution to Complement Evasion.

    Science.gov (United States)

    van der Maten, Erika; van den Broek, Bryan; de Jonge, Marien I; Rensen, Kim J W; Eleveld, Marc J; Zomer, Aldert L; Cremers, Amelieke J H; Ferwerda, Gerben; de Groot, Ronald; Langereis, Jeroen D; van der Flier, Michiel

    2018-04-01

    The pneumococcal capsular serotype is an important determinant of complement resistance and invasive disease potential, but other virulence factors have also been found to contribute. Pneumococcal surface protein C (PspC), a highly variable virulence protein that binds complement factor H to evade C3 opsonization, is divided into two subgroups: choline-bound subgroup I and LPxTG-anchored subgroup II. The prevalence of different PspC subgroups in invasive pneumococcal disease (IPD) and functional differences in complement evasion are unknown. The prevalence of PspC subgroups in IPD isolates was determined in a collection of 349 sequenced strains of Streptococcus pneumoniae isolated from adult patients. pspC deletion mutants and isogenic pspC switch mutants were constructed to study differences in factor H binding and complement evasion in relation to capsule thickness. Subgroup I pspC was far more prevalent in IPD isolates than subgroup II pspC The presence of capsule was associated with a greater ability of bound factor H to reduce complement opsonization. Pneumococcal subgroup I PspC bound significantly more factor H and showed more effective complement evasion than subgroup II PspC in isogenic encapsulated pneumococci. We conclude that variation in the PspC subgroups, independent of capsule serotypes, affects pneumococcal factor H binding and its ability to evade complement deposition. Copyright © 2018 American Society for Microbiology.

  2. Correction of X-ray diffraction profiles in linear-type PSPC by position factor

    International Nuclear Information System (INIS)

    Takahashi, Toshio

    1992-01-01

    PSPC (Position Sensitive Proportional Counter) makes it possible to obtain one-dimentional diffraction profiles without mechanical scanning. In a linear-type PSPC, the obtained profiles need correcting, because the position factor influences the intensity of the diffracted X-ray beam and the counting rate at each position on PSPC. The distances from the specimen are not the same at the center and at the edge of the detector, and the intensity decreases at the edge because of radiation and absorption. The counting rate varies with the incident angle of the diffracted beam at each position on PSPC. The position factor f i at channel i of the multichannel-analyser is given by f i = cos 4 α i ·exp{-μR(1/cosα i -1)} where R is the distance between the specimen and the center of PSPC, μ is the linear absorption coefficient and α i is the incident angle of the diffracted beam at channel i. The background profiles of silica gel powder were measured with CrKα and CuKα. The parameters of the model function were fitted to the profiles by the non-linear least squares method. The agreement between these parameters and the calculated values shows that the position factor can correct the measured profiles properly. (author)

  3. RNA-binding protein PSPC1 promotes the differentiation-dependent nuclear export of adipocyte RNAs

    DEFF Research Database (Denmark)

    Wang, Jiexin; Rajbhandari, Prashant; Damianov, Andrey

    2017-01-01

    A highly orchestrated gene expression program establishes the properties that define mature adipocytes, but the contribution of posttranscriptional factors to the adipocyte phenotype is poorly understood. Here we have shown that the RNA-binding protein PSPC1, a component of the paraspeckle complex...

  4. Spectral and Temporal Characteristics of X-Ray-Bright Stars in the Pleiades

    Science.gov (United States)

    Gagne, Marc; Caillault, Jean-Pierre; Stauffer, John R.

    1995-01-01

    We follow up our deep ROSAT imaging survey of the Pleiades (Stauffer et al. 1994) with an analysis of the spectral and temporal characteristics of the X-ray-bright stars in the Pleiades. Raymond & Smith (1977) one and two-temperature models have been used to fit the position-sensitive proportional counter (PSPC) pulse-height spectra of the dozen or so brightest sources associated with late-type Pleiades members. The best-fit temperatures suggest hot coronal temperatures for K, M, and rapidly rotating G stars, and cooler temperatures for F and slowly rotating G stars. In order to probe the many less X-ray-luminous stars, we have generated composite spectra by combining net counts from all Pleiades members according to spectral type and rotational velocity. Model fits to the composite spectra confirm the trend seen in the individual spectral fits. Particularly interesting is the apparent dependence of coronal temperature on L(sub x)/L(sub bol). A hardness-ratio analysis also confirms some of these trends. The PSPC data have also revealed a dozen or so strong X-ray flares with peak X-ray luminosities in excess of approx. 10(exp 30) ergs/sec. We have modeled the brightest of these flares with a simple quasi-static cooling loop model. The peak temperature and emission measure and the inferred electron density and plasma volume suggest a very large scale flaring event. The PSPC data were collected over a period of approx. 18 months, allowing us to search for source variability on timescales ranging from less than a day (in the case of flares) to more than a year between individual exposures. On approximately year-long timescales, roughly 25% of the late-type stars are variable. Since the Pleiades was also intensively monitored by the imaging instruments on the Einstein Observatory, we have examined X-ray luminosity variations on the 10 yr timescale between Einstein and ROSAT and find that up to 40% of the late-type stars are X-ray variable. Since there is only marginal

  5. Spectral Subtraction Approach for Interference Reduction of MIMO Channel Wireless Systems

    Directory of Open Access Journals (Sweden)

    Tomohiro Ono

    2005-08-01

    Full Text Available In this paper, a generalized spectral subtraction approach for reducing additive impulsive noise, narrowband signals, white Gaussian noise and DS-CDMA interferences in MIMO channel DS-CDMA wireless communication systems is investigated. The interference noise reduction or suppression is essential problem in wireless mobile communication systems to improve the quality of communication. The spectrum subtraction scheme is applied to the interference noise reduction problems for noisy MIMO channel systems. The interferences in space and time domain signals can effectively be suppressed by selecting threshold values, and the computational load with the FFT is not large. Further, the fading effects of channel are compensated by spectral modification with the spectral subtraction process. In the simulations, the effectiveness of the proposed methods for the MIMO channel DS-CDMA is shown to compare with the conventional MIMO channel DS-CDMA.

  6. Importance of spatial and spectral data reduction in the detection of internal defects in food products.

    Science.gov (United States)

    Zhang, Xuechen; Nansen, Christian; Aryamanesh, Nader; Yan, Guijun; Boussaid, Farid

    2015-04-01

    Despite the importance of data reduction as part of the processing of reflection-based classifications, this study represents one of the first in which the effects of both spatial and spectral data reductions on classification accuracies are quantified. Furthermore, the effects of approaches to data reduction were quantified for two separate classification methods, linear discriminant analysis (LDA) and support vector machine (SVM). As the model dataset, reflection data were acquired using a hyperspectral camera in 230 spectral channels from 401 to 879 nm (spectral resolution of 2.1 nm) from field pea (Pisum sativum) samples with and without internal pea weevil (Bruchus pisorum) infestation. We deployed five levels of spatial data reduction (binning) and eight levels of spectral data reduction (40 datasets). Forward stepwise LDA was used to select and include only spectral channels contributing the most to the separation of pixels from non-infested and infested field peas. Classification accuracies obtained with LDA and SVM were based on the classification of independent validation datasets. Overall, SVMs had significantly higher classification accuracies than LDAs (P food products with internal defects, and it highlights that spatial and spectral data reductions can (1) improve classification accuracies, (2) vastly decrease computer constraints, and (3) reduce analytical concerns associated with classifications of large and high-dimensional datasets.

  7. GBTIDL: Reduction and Analysis of GBT Spectral Line Data

    Science.gov (United States)

    Marganian, P.; Garwood, R. W.; Braatz, J. A.; Radziwill, N. M.; Maddalena, R. J.

    2013-03-01

    GBTIDL is an interactive package for reduction and analysis of spectral line data taken with the Robert C. Byrd Green Bank Telescope (GBT). The package, written entirely in IDL, consists of straightforward yet flexible calibration, averaging, and analysis procedures (the "GUIDE layer") modeled after the UniPOPS and CLASS data reduction philosophies, a customized plotter with many built-in visualization features, and Data I/O and toolbox functionality that can be used for more advanced tasks. GBTIDL makes use of data structures which can also be used to store intermediate results. The package consumes and produces data in GBT SDFITS format. GBTIDL can be run online and have access to the most recent data coming off the telescope, or can be run offline on preprocessed SDFITS files.

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

    Science.gov (United States)

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

    2017-03-01

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

  9. A new approach to passivity preserving model reduction : the dominant spectral zero method

    NARCIS (Netherlands)

    Ionutiu, R.; Rommes, J.; Antoulas, A.C.; Roos, J.; Costa, L.R.J.

    2010-01-01

    A new model reduction method for circuit simulation is presented, which preserves passivity by interpolating dominant spectral zeros. These are computed as poles of an associated Hamiltonian system, using an iterative solver: the subspace accelerated dominant pole algorithm (SADPA). Based on a

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

    Directory of Open Access Journals (Sweden)

    Fubiao Feng

    2017-03-01

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

  11. Metal artefact reduction in gemstone spectral imaging dual-energy CT with and without metal artefact reduction software

    International Nuclear Information System (INIS)

    Lee, Young Han; Song, Ho-Taek; Kim, Sungjun; Suh, Jin-Suck; Park, Kwan Kyu

    2012-01-01

    To assess the usefulness of gemstone spectral imaging (GSI) dual-energy CT (DECT) with/without metal artefact reduction software (MARs). The DECTs were performed using fast kV-switching GSI between 80 and 140 kV. The CT data were retro-reconstructed with/without MARs, by different displayed fields-of-view (DFOV), and with synthesised monochromatic energy in the range 40-140 keV. A phantom study of size and CT numbers was performed in a titanium plate and a stainless steel plate. A clinical study was performed in 26 patients with metallic hardware. All images were retrospectively reviewed in terms of the visualisation of periprosthetic regions and the severity of beam-hardening artefacts by using a five-point scale. The GSI-MARs reconstruction can markedly reduce the metal-related artefacts, and the image quality was affected by the prosthesis composition and DFOV. The spectral CT numbers of the prosthesis and periprosthetic regions showed different patterns on stainless steel and titanium plates. Dual-energy CT with GSI-MARs can reduce metal-related artefacts and improve the delineation of the prosthesis and periprosthetic region. We should be cautious when using GSI-MARs because the image quality was affected by the prosthesis composition, energy (in keV) and DFOV. The metallic composition and size should be considered in metallic imaging with GSI-MARs reconstruction. circle Metal-related artefacts can be troublesome on musculoskeletal computed tomography (CT). circle Gemstone spectral imaging (GSI) with dual-energy CT (DECT) offers a novel solution circle GSI and metallic artefact reduction software (GSI-MAR) can markedly reduce these artefacts. circle However image quality is influenced by the prosthesis composition and other parameters. circle We should be aware about potential overcorrection when using GSI-MARs. (orig.)

  12. The spectral effects of subsolidus reduction of olivine and pyroxene

    Science.gov (United States)

    Britt, D. T.

    1993-01-01

    The surfaces of atmosphereless bodies are subjected to a variety of chemical, thermal, accretionary, and shock processes related to their regolith environment. These processes are responsible for a number of alterations that occur in regoliths. Alterations include particle size commutation, implantation of solar wind gases, formation of agglutinates, spectral darkening, and, in the lunar case, the development of the very strong red continuum slope in the visible and near infrared spectra. A great deal of work has pointed to the role of agglutinates as the principal agent for darkening and reddening the lunar soil. The measures of regolith maturity are strongly linked to the accumulation of agglutinates. Recent work has suggested that the finest fractions of agglutinitic glass are major source of the spectral red slope. In particular, the red slope is most strongly associated with the agglutinitic glasses that are rich in blebs of sub-micron sized metal particles. It is thought that these metal particles, because of their size and scattering efficiently relative to the wavelength of light, are responsible for the red continuum slope. This fine fraction of metal particles is produced primarily by reduction of Fe(+2) from silicates. One mechanism for the reduction process is the reaction of solar implanted wind protons with the regolith soil during impact events. In this case the presence of hydrogen creates a reducing environment and the thermal pulse from the impact greatly speeds the reaction kinetics. To explore other reducing and thermal environments a series of experiments were done using samples in evacuated capsules buffered by Tantalum and heated to subsolidus temperatures.

  13. Application of digital waveform processing to position-sensitive proportional counter

    International Nuclear Information System (INIS)

    Takenaka, Yasuto; Uritani, Akira; Mori, Chizuo

    1995-01-01

    In a charge-division type position-sensitive proportional counter (PSPC) with an anode wire of small resistance, a reflected component from an opposite end and thermal noise involved in signals deteriorate the position resolution of the PSPC. A digital waveform processing method was applied to the reduction of these undesirable effects by skillfully utilizing their signal characteristics that can be observed as inversely correlative signals between two-output signals from both sides of the PSPC. The digital waveform processing could improve the position resolution compared to a conventional pulse height processing method with analog filters. When the digital waveform processing was applied to signals of an equivalent circuit simulating the PSPC, the position resolutions defined by the full width at half maximum were improved to about 30% of those of conventional analog pulse processing. In the case of an actual PSPC, the position resolutions by the digital waveform processing were improved by 4-10% as compared with those of conventional pulse height processing. (author)

  14. Spectral OCT with speckle contrast reduction for evaluation of the healing process after PRK and transepithelial PRK

    OpenAIRE

    Kaluzny, Bartlomiej J.; Szkulmowski, Maciej; Bukowska, Danuta M.; Wojtkowski, Maciej

    2014-01-01

    We evaluate Spectral OCT (SOCT) with a speckle contrast reduction technique using resonant scanner for assessment of corneal surface changes after excimer laser photorefractive keratectomy (PRK) and we compare healing process between conventional PRK and transepithelial PRK. The measurements were performed before and after the surgery. Obtained results show that SOCT with a resonant scanner speckle contrast reduction is capable of providing information regarding the healing process after PRK....

  15. Radiation dose reduction in parasinus CT by spectral shaping

    Energy Technology Data Exchange (ETDEWEB)

    May, Matthias S.; Brand, Michael; Lell, Michael M.; Uder, Michael; Wuest, Wolfgang [University Hospital Erlangen, Department of Radiology, Erlangen (Germany); Sedlmair, Martin; Allmendinger, Thomas [Siemens Healthcare GmbH, Forchheim (Germany)

    2017-02-15

    Spectral shaping aims to narrow the X-ray spectrum of clinical CT. The aim of this study was to determine the image quality and the extent of radiation dose reduction that can be achieved by tin prefiltration for parasinus CT. All scans were performed with a third generation dual-source CT scanner. A study protocol was designed using 100 kV tube voltage with tin prefiltration (200 mAs) that provides image noise levels comparable to a low-dose reference protocol using 100 kV without spectral shaping (25 mAs). One hundred consecutive patients were prospectively enrolled and randomly assigned to the study or control group. All patients signed written informed consent. The study protocol was approved by the local Institutional Review Board and applies to the HIPAA. Subjective and objective image quality (attenuation values, image noise, and contrast-to-noise ratio (CNR)) were assessed. Radiation exposure was assessed as volumetric CT dose index, and effective dose was estimated. Mann-Whitney U test was performed for radiation exposure and for image noise comparison. All scans were of diagnostic image quality. Image noise in air, in the retrobulbar fat, and in the eye globe was comparable between both groups (all p > 0.05). CNR{sub eye} {sub globe/air} did not differ significantly between both groups (p = 0.7). Radiation exposure (1.7 vs. 2.1 mGy, p < 0.01) and effective dose (0.055 vs. 0.066 mSv, p < 0.01) were significantly reduced in the study group. Radiation dose can be further reduced by 17% for low-dose parasinus CT by tin prefiltration maintaining diagnostic image quality. (orig.)

  16. Radiation dose reduction in parasinus CT by spectral shaping

    International Nuclear Information System (INIS)

    May, Matthias S.; Brand, Michael; Lell, Michael M.; Uder, Michael; Wuest, Wolfgang; Sedlmair, Martin; Allmendinger, Thomas

    2017-01-01

    Spectral shaping aims to narrow the X-ray spectrum of clinical CT. The aim of this study was to determine the image quality and the extent of radiation dose reduction that can be achieved by tin prefiltration for parasinus CT. All scans were performed with a third generation dual-source CT scanner. A study protocol was designed using 100 kV tube voltage with tin prefiltration (200 mAs) that provides image noise levels comparable to a low-dose reference protocol using 100 kV without spectral shaping (25 mAs). One hundred consecutive patients were prospectively enrolled and randomly assigned to the study or control group. All patients signed written informed consent. The study protocol was approved by the local Institutional Review Board and applies to the HIPAA. Subjective and objective image quality (attenuation values, image noise, and contrast-to-noise ratio (CNR)) were assessed. Radiation exposure was assessed as volumetric CT dose index, and effective dose was estimated. Mann-Whitney U test was performed for radiation exposure and for image noise comparison. All scans were of diagnostic image quality. Image noise in air, in the retrobulbar fat, and in the eye globe was comparable between both groups (all p > 0.05). CNR_e_y_e _g_l_o_b_e_/_a_i_r did not differ significantly between both groups (p = 0.7). Radiation exposure (1.7 vs. 2.1 mGy, p < 0.01) and effective dose (0.055 vs. 0.066 mSv, p < 0.01) were significantly reduced in the study group. Radiation dose can be further reduced by 17% for low-dose parasinus CT by tin prefiltration maintaining diagnostic image quality. (orig.)

  17. SpectralNET – an application for spectral graph analysis and visualization

    Directory of Open Access Journals (Sweden)

    Schreiber Stuart L

    2005-10-01

    Full Text Available Abstract Background Graph theory provides a computational framework for modeling a variety of datasets including those emerging from genomics, proteomics, and chemical genetics. Networks of genes, proteins, small molecules, or other objects of study can be represented as graphs of nodes (vertices and interactions (edges that can carry different weights. SpectralNET is a flexible application for analyzing and visualizing these biological and chemical networks. Results Available both as a standalone .NET executable and as an ASP.NET web application, SpectralNET was designed specifically with the analysis of graph-theoretic metrics in mind, a computational task not easily accessible using currently available applications. Users can choose either to upload a network for analysis using a variety of input formats, or to have SpectralNET generate an idealized random network for comparison to a real-world dataset. Whichever graph-generation method is used, SpectralNET displays detailed information about each connected component of the graph, including graphs of degree distribution, clustering coefficient by degree, and average distance by degree. In addition, extensive information about the selected vertex is shown, including degree, clustering coefficient, various distance metrics, and the corresponding components of the adjacency, Laplacian, and normalized Laplacian eigenvectors. SpectralNET also displays several graph visualizations, including a linear dimensionality reduction for uploaded datasets (Principal Components Analysis and a non-linear dimensionality reduction that provides an elegant view of global graph structure (Laplacian eigenvectors. Conclusion SpectralNET provides an easily accessible means of analyzing graph-theoretic metrics for data modeling and dimensionality reduction. SpectralNET is publicly available as both a .NET application and an ASP.NET web application from http://chembank.broad.harvard.edu/resources/. Source code is

  18. Spectral OCT with speckle contrast reduction for evaluation of the healing process after PRK and transepithelial PRK.

    Science.gov (United States)

    Kaluzny, Bartlomiej J; Szkulmowski, Maciej; Bukowska, Danuta M; Wojtkowski, Maciej

    2014-04-01

    We evaluate Spectral OCT (SOCT) with a speckle contrast reduction technique using resonant scanner for assessment of corneal surface changes after excimer laser photorefractive keratectomy (PRK) and we compare healing process between conventional PRK and transepithelial PRK. The measurements were performed before and after the surgery. Obtained results show that SOCT with a resonant scanner speckle contrast reduction is capable of providing information regarding the healing process after PRK. The main difference between the healing processes of PRK and TransPRK, assessed by SOCT, was the time to cover the stroma with epithelium, which was shorter in the TransPRK group.

  19. Spectral CT with monochromatic imaging and metal artifacts reduction software for artifacts reduction of ¹²⁵I radioactive seeds in liver brachytherapy.

    Science.gov (United States)

    Yang, Qiuxia; Peng, Sheng; Wu, Jing; Ban, Xiaohua; He, Mingyan; Xie, Chuanmiao; Zhang, Rong

    2015-11-01

    To investigate the optimal monochromatic energy for artifacts reduction from (125)I seeds as well as image improvement in the vicinity of seeds on monochromatic images with and without metal artifacts reduction software (MARS) and to compare this with traditional 120-kVp images, so as to evaluate the application value of gemstone spectral imaging for reducing artifacts from (125)I seeds in liver brachytherapy. A total of 45 tumors from 25 patients treated with (125)I seed brachytherapy in the liver were enrolled in this study. Multiphasic spectral computed tomography (CT) scanning was performed for each patient. After a delay time of 15 s of portal vein phase, a traditional 120-kVp scan was performed, focusing on several planes of (125)I seeds only. The artifact index (AI) in the vicinity of seeds and the standard deviation (SD) of the CT density of region of interest in the outside liver parenchyma were calculated. Artifact appearance was evaluated and classified on reconstructed monochromatic S and 120-kVp images. Image quality in the vicinity of seeds of three data sets were evaluated using a 1-5 scale scoring method. The Friedman rank-sum test was used to estimate the scoring results of image quality. The greatest noise in monochromatic images was found at 40 keV (SD = 27.38, AI = 206.40). The optimal monochromatic energy was found at 75 keV, which provided almost the least image noise (SD = 10.01) and good performance in artifact reduction (AI = 102.73). Image noise and AI reduction at 75 keV was decreased by 63.44 and 50.23%, compared with at 40 keV. Near-field thick artifacts were obvious in all 45 lesions, in 120-kVp images, and 75-keV images, but basically reduced in 75 keV MARS images and artifacts completely invisible in 7 lesions. The number of diagnosable images (score ≥3) was significantly more in the 75-keV MARS group (28/45), and the 75-keV group (22/45) than in the 120-kVp group (11/45) (p improve image quality, even to a state of being

  20. Stellar Spectral Classification with Locality Preserving Projections ...

    Indian Academy of Sciences (India)

    With the help of computer tools and algorithms, automatic stellar spectral classification has become an area of current interest. The process of stellar spectral classification mainly includes two steps: dimension reduction and classification. As a popular dimensionality reduction technique, Principal Component Analysis (PCA) ...

  1. ULTRAVIOLET RAMAN SPECTRAL SIGNATURE ACQUISITION: UV RAMAN SPECTRAL FINGERPRINTS.

    Energy Technology Data Exchange (ETDEWEB)

    SEDLACEK,III, A.J.FINFROCK,C.

    2002-09-01

    As a member of the science-support part of the ITT-lead LISA development program, BNL is tasked with the acquisition of UV Raman spectral fingerprints and associated scattering cross-sections for those chemicals-of-interest to the program's sponsor. In support of this role, the present report contains the first installment of UV Raman spectral fingerprint data on the initial subset of chemicals. Because of the unique nature associated with the acquisition of spectral fingerprints for use in spectral pattern matching algorithms (i.e., CLS, PLS, ANN) great care has been undertaken to maximize the signal-to-noise and to minimize unnecessary spectral subtractions, in an effort to provide the highest quality spectral fingerprints. This report is divided into 4 sections. The first is an Experimental section that outlines how the Raman spectra are performed. This is then followed by a section on Sample Handling. Following this, the spectral fingerprints are presented in the Results section where the data reduction process is outlined. Finally, a Photographs section is included.

  2. Is there Place for Perfectionism in the NIR Spectral Data Reduction?

    Science.gov (United States)

    Chilingarian, Igor

    2017-09-01

    "Despite the crucial importance of the near-infrared spectral domain for understanding the star formation and galaxy evolution, NIR observations and data reduction represent a significant challenge. The known complexity of NIR detectors is aggravated by the airglow emission in the upper atmosphere and the water absorption in the troposphere so that up until now, the astronomical community is divided on the issue whether ground based NIR spectroscopy has a future or should it move completely to space (JWST, Euclid, WFIRST). I will share my experience of pipeline development for low- and intermediate-resolution spectrographs operated at Magellan and MMT. The MMIRS data reduction pipeline became the first example of the sky subtraction quality approaching the limit set by the Poisson photon noise and demonstrated the feasibility of low-resolution (R=1200-3000) NIR spectroscopy from the ground even for very faint (J=24.5) continuum sources. On the other hand, the FIRE Bright Source Pipeline developed specifically for high signal-to-noise intermediate resolution stellar spectra proves that systematics in the flux calibration and telluric absorption correction can be pushed down to the (sub-)percent level. My conclusion is that even though substantial effort and time investment is needed to design and develop NIR spectroscopic pipelines for ground based instruments, it will pay off, if done properly, and open new windows of opportunity in the ELT era."

  3. Soft X-Ray Observations of a Complete Sample of X-Ray--selected BL Lacertae Objects

    Science.gov (United States)

    Perlman, Eric S.; Stocke, John T.; Wang, Q. Daniel; Morris, Simon L.

    1996-01-01

    We present the results of ROSAT PSPC observations of the X-ray selected BL Lacertae objects (XBLs) in the complete Einstein Extended Medium Sensitivity Survey (EM MS) sample. None of the objects is resolved in their respective PSPC images, but all are easily detected. All BL Lac objects in this sample are well-fitted by single power laws. Their X-ray spectra exhibit a variety of spectral slopes, with best-fit energy power-law spectral indices between α = 0.5-2.3. The PSPC spectra of this sample are slightly steeper than those typical of flat ratio-spectrum quasars. Because almost all of the individual PSPC spectral indices are equal to or slightly steeper than the overall optical to X-ray spectral indices for these same objects, we infer that BL Lac soft X-ray continua are dominated by steep-spectrum synchrotron radiation from a broad X-ray jet, rather than flat-spectrum inverse Compton radiation linked to the narrower radio/millimeter jet. The softness of the X-ray spectra of these XBLs revives the possibility proposed by Guilbert, Fabian, & McCray (1983) that BL Lac objects are lineless because the circumnuclear gas cannot be heated sufficiently to permit two stable gas phases, the cooler of which would comprise the broad emission-line clouds. Because unified schemes predict that hard self-Compton radiation is beamed only into a small solid angle in BL Lac objects, the steep-spectrum synchrotron tail controls the temperature of the circumnuclear gas at r ≤ 1018 cm and prevents broad-line cloud formation. We use these new ROSAT data to recalculate the X-ray luminosity function and cosmological evolution of the complete EMSS sample by determining accurate K-corrections for the sample and estimating the effects of variability and the possibility of incompleteness in the sample. Our analysis confirms that XBLs are evolving "negatively," opposite in sense to quasars, with Ve/Va = 0.331±0.060. The statistically significant difference between the values for X

  4. The Galah Survey: Classification and Diagnostics with t-SNE Reduction of Spectral Information

    Energy Technology Data Exchange (ETDEWEB)

    Traven, G.; Zwitter, T.; Žerjal, M. [Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, 1000 Ljubljana (Slovenia); Matijevič, G. [Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, D-14482 Potsdam (Germany); Kos, J.; Bland-Hawthorn, J.; De Silva, G.; Sharma, S. [Sydney Institute for Astronomy, School of Physics, A28, The University of Sydney, NSW 2006 (Australia); Asplund, M.; Freeman, K.; Lin, J.; Da Costa, G.; Duong, L. [Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 2611 (Australia); Casey, A. R. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Martell, S. L. [School of Physics, University of New South Wales, Sydney, NSW 2052 (Australia); Schlesinger, K. J. [Research School of Astronomy and Astrophysics, Mount Stromlo Observatory, Cotter Road, Weston Creek, ACT 2611 (Australia); Simpson, J. D. [Australian Astronomical Observatory, North Ryde, NSW 2113 (Australia); Zucker, D. B. [Australian Astronomical Observatory, P.O. Box 915, North Ryde, NSW 1670 (Australia); Anguiano, B. [Department of Physics and Astronomy, Macquarie University, North Ryde, NSW 2109 (Australia); Horner, J., E-mail: gregor.traven@fmf.uni-lj.si [Computational Engineering and Science Research Centre, University of Southern Queensland, Towoomba QLD 4350 (Australia); and others

    2017-02-01

    Galah is an ongoing high-resolution spectroscopic survey with the goal of disentangling the formation history of the Milky Way using the fossil remnants of disrupted star formation sites that are now dispersed around the Galaxy. It is targeting a randomly selected magnitude-limited ( V ≤ 14) sample of stars, with the goal of observing one million objects. To date, 300,000 spectra have been obtained. Not all of them are correctly processed by parameter estimation pipelines, and we need to know about them. We present a semi-automated classification scheme that identifies different types of peculiar spectral morphologies in an effort to discover and flag potentially problematic spectra and thus help to preserve the integrity of the survey results. To this end, we employ the recently developed dimensionality reduction technique t-SNE ( t -distributed stochastic neighbor embedding), which enables us to represent the complex spectral morphology in a two-dimensional projection map while still preserving the properties of the local neighborhoods of spectra. We find that the majority (178,483) of the 209,533 Galah spectra considered in this study represents normal single stars, whereas 31,050 peculiar and problematic spectra with very diverse spectral features pertaining to 28,579 stars are distributed into 10 classification categories: hot stars, cool metal-poor giants, molecular absorption bands, binary stars, H α /H β emission, H α /H β emission superimposed on absorption, H α /H β P-Cygni, H α /H β inverted P-Cygni, lithium absorption, and problematic. Classified spectra with supplementary information are presented in the catalog, indicating candidates for follow-up observations and population studies of the short-lived phases of stellar evolution.

  5. Quantifying metal artefact reduction using virtual monochromatic dual-layer detector spectral CT imaging in unilateral and bilateral total hip prostheses

    NARCIS (Netherlands)

    Wellenberg, R. H. H.; Boomsma, M. F.; van Osch, J. A. C.; Vlassenbroek, A.; Milles, J.; Edens, M. A.; Streekstra, G. J.; Slump, C. H.; Maas, M.

    2017-01-01

    To quantify the impact of prosthesis material and design on the reduction of metal artefacts in total hip arthroplasties using virtual monochromatic dual-layer detector Spectral CT imaging. The water-filled total hip arthroplasty phantom was scanned on a novel 128-slice Philips IQon dual-layer

  6. Spectral CT with metal artifacts reduction software for improvement of tumor visibility in the vicinity of gold fiducial markers.

    Science.gov (United States)

    Brook, Olga R; Gourtsoyianni, Sofia; Brook, Alexander; Mahadevan, Anand; Wilcox, Carol; Raptopoulos, Vassilios

    2012-06-01

    To evaluate spectral computed tomography (CT) with metal artifacts reduction software (MARS) for reduction of metal artifacts associated with gold fiducial seeds. Thirteen consecutive patients with 37 fiducial seeds implanted for radiation therapy of abdominal lesions were included in this HIPAA-compliant, institutional review board-approved prospective study. Six patients were women (46%) and seven were men (54%). The mean age was 61.1 years (median, 58 years; range, 29-78 years). Spectral imaging was used for arterial phase CT. Images were reconstructed with and without MARS in axial, coronal, and sagittal planes. Two radiologists independently reviewed reconstructions and selected the best image, graded the visibility of the tumor, and assessed the amount of artifacts in all planes. A linear-weighted κ statistic and Wilcoxon signed-rank test were used to assess interobserver variability. Histogram analysis with the Kolmogorov-Smirnov test was used for objective evaluation of artifacts reduction. Fiducial seeds were placed in pancreas (n = 5), liver (n = 7), periportal lymph nodes (n = 1), and gallbladder bed (n = 1). MARS-reconstructed images received a better grade than those with standard reconstruction in 60% and 65% of patients by the first and second radiologist, respectively. Tumor visibility was graded higher with standard versus MARS reconstruction (grade, 3.7 ± 1.0 vs 2.8 ± 1.1; P = .001). Reduction of blooming was noted on MARS-reconstructed images (P = .01). Amount of artifacts, for both any and near field, was significantly smaller on sagittal and coronal MARS-reconstructed images than on standard reconstructions (P MARS-reconstructed images than on standard reconstructions (P MARS than with standard reconstruction in 35 of 37 patients (P MARS improved tumor visibility in the vicinity of gold fiducial seeds.

  7. The Inhibitory Effects of Purple Sweet Potato Color on Hepatic Inflammation Is Associated with Restoration of NAD⁺ Levels and Attenuation of NLRP3 Inflammasome Activation in High-Fat-Diet-Treated Mice.

    Science.gov (United States)

    Wang, Xin; Zhang, Zi-Feng; Zheng, Gui-Hong; Wang, Ai-Min; Sun, Chun-Hui; Qin, Su-Ping; Zhuang, Juan; Lu, Jun; Ma, Dai-Fu; Zheng, Yuan-Lin

    2017-08-08

    Purple sweet potato color (PSPC), a class of naturally occurring anthocyanins, exhibits beneficial effects on metabolic syndrome. Sustained inflammation plays a crucial role in the pathogenesis of metabolic syndrome. Here we explored the effects of PSPC on high-fat diet (HFD)-induced hepatic inflammation and the mechanisms underlying these effects. Mice were divided into four groups: Control group, HFD group, HFD + PSPC group, and PSPC group. PSPC was administered by daily oral gavage at doses of 700 mg/kg/day for 20 weeks. Nicotinamide riboside (NR) was used to increase NAD⁺ levels. Our results showed that PSPC effectively ameliorated obesity and liver injuries in HFD-fed mice. Moreover, PSPC notably blocked hepatic oxidative stress in HFD-treated mice. Furthermore, PSPC dramatically restored NAD⁺ level to abate endoplasmic reticulum stress (ER stress) in HFD-treated mouse livers, which was confirmed by NR treatment. Consequently, PSPC remarkably suppressed the nuclear factor-κB (NF-κB) p65 nuclear translocation and nucleotide oligomerization domain protein1/2 (NOD1/2) signaling in HFD-treated mouse livers. Thereby, PSPC markedly diminished the NLR family, pyrin domain containing 3 (NLRP3) inflammasome activation, ultimately lowering the expressions of inflammation-related genes in HFD-treated mouse livers. In summary, PSPC protected against HFD-induced hepatic inflammation by boosting NAD⁺ level to inhibit NLRP3 inflammasome activation.

  8. A Spectral Algorithm for Envelope Reduction of Sparse Matrices

    Science.gov (United States)

    Barnard, Stephen T.; Pothen, Alex; Simon, Horst D.

    1993-01-01

    The problem of reordering a sparse symmetric matrix to reduce its envelope size is considered. A new spectral algorithm for computing an envelope-reducing reordering is obtained by associating a Laplacian matrix with the given matrix and then sorting the components of a specified eigenvector of the Laplacian. This Laplacian eigenvector solves a continuous relaxation of a discrete problem related to envelope minimization called the minimum 2-sum problem. The permutation vector computed by the spectral algorithm is a closest permutation vector to the specified Laplacian eigenvector. Numerical results show that the new reordering algorithm usually computes smaller envelope sizes than those obtained from the current standard algorithms such as Gibbs-Poole-Stockmeyer (GPS) or SPARSPAK reverse Cuthill-McKee (RCM), in some cases reducing the envelope by more than a factor of two.

  9. A comparison of dimension reduction methods with application to multi-spectral images of sand used in concrete

    DEFF Research Database (Denmark)

    Clemmensen, Line Katrine Harder; Hansen, M. E.; Ersbøll, Bjarne Kjær

    2010-01-01

    This paper presents a comparison of dimension reduction methods based on a novel machine vision application for estimating moisture content in sand used to make concrete. For the application in question it is very important to know the moisture content of the sand so as to ensure good-quality...... sand types were examined with 20-60 images for each type. To reduce the amount of data, features were extracted from the multi-spectral images; the features were summary statistics on single bands and pairs of bands as well as morphological summaries. The number of features (2,016) is high in relation...

  10. Antibacterial properties of 3-(phenylsulfonyl)-2-pyrazinecarbonitrile.

    Science.gov (United States)

    Rajamuthiah, Rajmohan; Jayamani, Elamparithi; Majed, Hiwa; Conery, Annie L; Kim, Wooseong; Kwon, Bumsup; Fuchs, Beth Burgwyn; Kelso, Michael J; Ausubel, Frederick M; Mylonakis, Eleftherios

    2015-11-15

    The emergence of multidrug-resistant bacterial strains has heightened the need for new antimicrobial agents based on novel chemical scaffolds that are able to circumvent current modes of resistance. We recently developed a whole-animal drug-screening methodology in pursuit of this goal and now report the discovery of 3-(phenylsulfonyl)-2-pyrazinecarbonitrile (PSPC) as a novel antibacterial effective against resistant nosocomial pathogens. The minimum inhibitory concentrations (MIC) of PSPC against Staphylococcus aureus and Enterococcus faecium were 4 μg/mL and 8 μg/mL, respectively, whereas the MICs were higher against the Gram-negative bacteria Klebsiella pneumoniae (64 μg/mL), Acinetobacter baumannii (32 μg/mL), Pseudomonas aeruginosa (>64 μg/mL), and Enterobacter spp. (>64 μg/mL). However, co-treatment of PSPC with the efflux pump inhibitor phenylalanine arginyl β-naphthylamide (PAβN) or with sub-inhibitory concentrations of the lipopeptide antibiotic polymyxin B reduced the MICs of PSPC against the Gram-negative strains by >4-fold. A sulfide analog of PSPC (PSPC-1S) showed no antibacterial activity, whereas the sulfoxide analog (PSPC-6S) showed identical activity as PSPC across all strains, confirming structure-dependent activity for PSPC and suggesting a target-based mechanism of action. PSPC displayed dose dependent toxicity to both Caenorhabditis elegans and HEK-293 mammalian cells, culminating with a survival rate of 16% (100 μg/mL) and 8.5% (64 μg/mL), respectively, at the maximum tested concentration. However, PSPC did not result in hemolysis of erythrocytes, even at a concentration of 64 μg/mL. Together these results support PSPC as a new chemotype suitable for further development of new antibiotics against Gram-positive and Gram-negative bacteria. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. Reduction of artifacts caused by orthopedic hardware in the spine in spectral detector CT examinations using virtual monoenergetic image reconstructions and metal-artifact-reduction algorithms

    Energy Technology Data Exchange (ETDEWEB)

    Grosse Hokamp, Nils; Neuhaus, V.; Abdullayev, N.; Laukamp, K.; Lennartz, S.; Mpotsaris, A.; Borggrefe, J. [University Hospital Cologne, Department of Diagnostic and Interventional Radiology, Cologne (Germany)

    2018-02-15

    Aim of this study was to assess the artifact reduction in patients with orthopedic hardware in the spine as provided by (1) metal-artifact-reduction algorithms (O-MAR) and (2) virtual monoenergetic images (MonoE) as provided by spectral detector CT (SDCT) compared to conventional iterative reconstruction (CI). In all, 28 consecutive patients with orthopedic hardware in the spine who underwent SDCT-examinations were included. CI, O-MAR and MonoE (40-200 keV) images were reconstructed. Attenuation (HU) and noise (SD) were measured in order to calculate signal-to-noise ratio (SNR) of paravertebral muscle and spinal canal. Subjective image quality was assessed by two radiologists in terms of image quality and extent of artifact reduction. O-MAR and high-keV MonoE showed significant decrease of hypodense artifacts in terms of higher attenuation as compared to CI (CI vs O-MAR, 200 keV MonoE: -396.5HU vs. -115.2HU, -48.1HU; both p ≤ 0.001). Further, artifacts as depicted by noise were reduced in O-MAR and high-keV MonoE as compared to CI in (1) paravertebral muscle and (2) spinal canal - CI vs. O-MAR/200 keV: (1) 34.7 ± 19.0 HU vs. 26.4 ± 14.4 HU, p ≤ 0.05/27.4 ± 16.1, n.s.; (2) 103.4 ± 61.3 HU vs. 72.6 ± 62.6 HU/60.9 ± 40.1 HU, both p ≤ 0.001. Subjectively both O-MAR and high-keV images yielded an artifact reduction in up to 24/28 patients. Both, O-MAR and high-keV MonoE reconstructions as provided by SDCT lead to objective and subjective artifact reduction, thus the combination of O-MAR and MonoE seems promising for further reduction. (orig.)

  12. Prognosis for advanced-stage primary peritoneal serous papillary carcinoma and serous ovarian cancer in Taiwan.

    Science.gov (United States)

    Chao, Kuan-Chong; Chen, Yi-Jen; Juang, Chi-Mou; Lau, Hei-Yu; Wen, Kuo-Chang; Sung, Pi-Lin; Fang, Feng-Ying; Twu, Nae-Fang; Yen, Ming-Shyen

    2013-03-01

    To compare the prognosis of patients with advanced-stage primary peritoneal serous papillary carcinoma (PSPC) or papillary serous ovarian cancer (PSOC). This was a retrospective case-control study and included two study groups: one with stage III/IV PSPC (n = 38) patients and the other with PSOC (n = 53) patients. Patients were matched for histologic subtype (serous tumor), tumor stage, tumor grade, residual disease at the end of debulking surgery (primary or interval), and age (±5 years). Mean age was significantly greater for patients with PSPC (63.03 ± 11.88 years) than for patients with PSOC (55.92 ± 12.56 years, p = 0.008). Optimal debulking surgery was performed initially in 71.9% of PSPC patients and 66.0% of PSOC patients. In addition, 93.9% of PSPC patients and 92.3% of PSOC patients were treated with platinum-paclitaxel chemotherapy. The frequency of high-grade tumors was significantly higher in the PSPC (100%) than in the PSOC group (68.3%; p statistic). PFS was similar for advanced-stage PSPC and PSOC patients. Since the PSPC patients tended to be older and have more high-grade tumors, OS was shorter for PSPC than for POSC patients. Thus, management of the two types of cancer should not differ. Copyright © 2013. Published by Elsevier B.V.

  13. Contrast Dose and Radiation Dose Reduction in Abdominal Enhanced Computerized Tomography Scans with Single-phase Dual-energy Spectral Computerized Tomography Mode for Children with Solid Tumors

    OpenAIRE

    Tong Yu; Jun Gao; Zhi-Min Liu; Qi-Feng Zhang; Yong Liu; Ling Jiang; Yun Peng

    2017-01-01

    Background: Contrast dose and radiation dose reduction in computerized tomography (CT) scan for adult has been explored successfully, but there have been few studies on the application of low-concentration contrast in pediatric abdominal CT examinations. This was a feasibility study on the use of dual-energy spectral imaging and adaptive statistical iterative reconstruction (ASiR) for the reduction of radiation dose and iodine contrast dose in pediatric abdominal CT patients with solid tumors...

  14. Spectral Signature of Radiative Forcing by East Asian Dust-Soot Mixture

    Science.gov (United States)

    Zhu, A.; Ramanathan, V.

    2007-12-01

    The Pacific Dust Experiment (PACDEX) provides the first detailed sampling of dust-soot mixtures from the western Pacific to the eastern Pacific Ocean. The data includes down and up spectral irradiance, mixing state of dust and soot, and other aerosol properties. This study attempts to simulate the radiative forcing by dust-soot mixtures during the experimental period. The MODTRAN band model was employed to investigate the spectral signatures of solar irradiance change induced by aerosols at moderate spectral resolutions. For the short wave band (300-1100nm) used in this study, the reduction of downward irradiance at surface by aerosols greatly enhances with increasing wavelength in the UV band (300-400nm), reaches a maximum in the blue band, then gradually decreases toward the red band. In the near-IR band (700-1100nm), irradiance reduction by aerosols shows great fluctuations in the band with center wavelength at around 940nm, 820nm, 720nm, 760nm, 690nm, where the aerosol effect is overwhelmed by the water vapor and O2 absorptions. The spectral pattern of irradiance reduction varies for different aerosol species. The maximum reduction lies at around 450nm for soot, and shifting to about 490nm for East Asian mineral dust. It's worth noting that although soot aerosols reduce more irradiance than East Asian dust in the UV and blue band, the impact of dust to the irradiance exceeds that by soot at the longer wavelength band (i.e. around 550nm). The reduction of irradiance by East Asian dust (soot) in the UV band, visible band, and near-IR accounts for about 6% (10%), 56% (64%), and 38% (26%) of total irradiance reduction. As large amount of soot aerosols are involved during the long range transport of East Asian dust, the optical properties of dust aerosols are modified with different mixing state with soot, the spectral pattern of the irradiance reduction will be changed. The study of aerosol forcing at moderate spectral resolutions has the potential application for

  15. In Situ Spectral Kinetics of Cr(VI) Reduction by c-Type Cytochromes in A Suspension of Living Shewanella putrefaciens 200

    Science.gov (United States)

    Liu, Tongxu; Li, Xiaomin; Li, Fangbai; Han, Rui; Wu, Yundang; Yuan, Xiu; Wang, Ying

    2016-07-01

    Although c-type cytochromes (c-Cyts) mediating metal reduction have been mainly investigated with in vitro purified proteins of dissimilatory metal reducing bacteria, the in vivo behavior of c-Cyts is still unclear given the difficulty in measuring the proteins of intact cells. Here, c-Cyts in living Shewanella putrefaciens 200 (SP200) was successfully quantified using diffuse-transmission UV/Vis spectroscopy due to the strong absorbance of hemes, and the in situ spectral kinetics of Cr(VI) reduction by c-Cyts were examined over time. The reduced product Cr(III) observed on the cell surface may play a role in inhibiting the Cr(VI) reduction and reducing the cell numbers with high concentrations (>200 μM) of Cr(VI) evidenced by the 16S rRNA analysis. A brief kinetic model was established with two predominant reactions, redox transformation of c-Cyts and Cr(VI) reduction by reduced c-Cyts, but the fitting curves were not well-matched with c-Cyts data. The Cr(III)-induced inhibitory effect to the cellular function of redox transformation of c-Cyts was then added to the model, resulting in substantially improved the model fitting. This study provides a case of directly examining the reaction properties of outer-membrane enzyme during microbial metal reduction processes under physiological conditions.

  16. Prognosis for advanced-stage primary peritoneal serous papillary carcinoma and serous ovarian cancer in Taiwan

    Directory of Open Access Journals (Sweden)

    Kuan-Chong Chao

    2013-03-01

    Conclusion: PFS was similar for advanced-stage PSPC and PSOC patients. Since the PSPC patients tended to be older and have more high-grade tumors, OS was shorter for PSPC than for POSC patients. Thus, management of the two types of cancer should not differ.

  17. Yeast Interacting Proteins Database: YOL069W, YIL144W [Yeast Interacting Proteins Database

    Lifescience Database Archive (English)

    Full Text Available complex (Ndc80p-Nuf2p-Spc24p-Spc25p); involved in chromosome segregation, spindle checkpoint activity and kinetochore clustering...vity, kinetochore assembly and clustering Rows with this prey as prey (2) Rows with this prey as bait (0) 12...-Nuf2p-Spc24p-Spc25p); involved in chromosome segregation, spindle checkpoint activity and kinetochore clustering...d coiled-coil protein involved in chromosome segregation, spindle checkpoint activity, kinetochore assembly and clustering

  18. Assessing the potential of spectral induced polarization to detect in situ changes in iron reduction

    Science.gov (United States)

    Rosier, C. L.; Price, A.; Sharma, S.; Atekwana, E. A.

    2016-12-01

    The near surface geophysical technique Spectral Induced Polarization (SIP), provides promise as an effective method measuring in situ biofilm formation/development. Yet, potential mechanisms responsible for observed shifts in SIP response due to biofilm are not clearly understood. In order to address possible mechanisms we assessed the influence of Shewanella oneidensis (MR1) cell density (colony forming units; CFU), biofilm production (Bradford assay) and iron reduction metabolism (colorimetric assay) on SIP response. Laboratory measurements were collected over three months on columns packed with either iron-coated or iron-free sands and amended with artificial ground water and acetate in order to stimulate biofilm production and microbial iron reduction. Additionally, scanning electron microscopy (SEM) was used to confirm the presence of S. oneidensis cells and biofilm. Our results suggest that during early/initial stage (75 days) of column incubation, SIP measurements revealed that phase and imaginary conductivity responses decreased as the concentration of reduced iron decreased below 2.0 mM. In contrast, we observed only a moderate increase in phase and imaginary conductivity ( 30%) within iron-free columns as a result of increases in S. oneidensis cells (CFU 1.5 x 1011) and biofilm production (7.0 mg ml-1). SEM analysis confirmed the presence of biofilm and cells within both iron-coated and iron-free columns. We hypothesize that the production of microbial metabolic byproducts is a potential mechanism explaining large phase shits observed in previous studies ( 50 mrads) rather than the conductivity of cells or biofilm. Our findings provide support for the following: i) ratio of cells to biofilm production only moderately influences both phase and imaginary conductivity response and ii) largest phase and imaginary conductivity response resulted from microbial metabolism (i.e. iron reduction) and potentially biofilm trapping of conductive materials (i

  19. Influence of spectral resolution, spectral range and signal-to-noise ratio of Fourier transform infra-red spectra on identification of high explosive substances

    Science.gov (United States)

    Banas, Krzysztof; Banas, Agnieszka M.; Heussler, Sascha P.; Breese, Mark B. H.

    2018-01-01

    In the contemporary spectroscopy there is a trend to record spectra with the highest possible spectral resolution. This is clearly justified if the spectral features in the spectrum are very narrow (for example infra-red spectra of gas samples). However there is a plethora of samples (in the liquid and especially in the solid form) where there is a natural spectral peak broadening due to collisions and proximity predominately. Additionally there is a number of portable devices (spectrometers) with inherently restricted spectral resolution, spectral range or both, which are extremely useful in some field applications (archaeology, agriculture, food industry, cultural heritage, forensic science). In this paper the investigation of the influence of spectral resolution, spectral range and signal-to-noise ratio on the identification of high explosive substances by applying multivariate statistical methods on the Fourier transform infra-red spectral data sets is studied. All mathematical procedures on spectral data for dimension reduction, clustering and validation were implemented within R open source environment.

  20. Dimension Reduction of Multi-Spectral Satellite Image Time Series to Improve Deforestation Monitoring

    Directory of Open Access Journals (Sweden)

    Meng Lu

    2017-10-01

    Full Text Available In recent years, sequential tests for detecting structural changes in time series have been adapted for deforestation monitoring using satellite data. The input time series of such sequential tests is typically a vegetation index (e.g., NDVI, which uses two or three bands and ignores all other bands. Being limited to a vegetation index will not benefit from the richer spectral information provided by newly launched satellites and will bring two bottle-necks for deforestation monitoring. Firstly, it is hard to select a suitable vegetation index a priori. Secondly, a single vegetation index is typically affected by seasonal signals, noise and other natural dynamics, which decrease its power for deforestation detection. A novel multispectral time series change monitoring method that combines dimension reduction methods with a sequential hypothesis test is proposed to address these limitations. For each location, the proposed method automatically chooses a “suitable” index for deforestation monitoring. To demonstrate our approach, we implemented it in two study areas: a dry tropical forest in Bolivia (time series length: 444 with strong seasonality and a moist tropical forest in Brazil (time series length: 225 with almost no seasonality. Our method significantly improves accuracy in the presence of strong seasonality, in particular the temporal lag between disturbance and its detection.

  1. Principal Components as a Data Reduction and Noise Reduction Technique

    Science.gov (United States)

    Imhoff, M. L.; Campbell, W. J.

    1982-01-01

    The potential of principal components as a pipeline data reduction technique for thematic mapper data was assessed and principal components analysis and its transformation as a noise reduction technique was examined. Two primary factors were considered: (1) how might data reduction and noise reduction using the principal components transformation affect the extraction of accurate spectral classifications; and (2) what are the real savings in terms of computer processing and storage costs of using reduced data over the full 7-band TM complement. An area in central Pennsylvania was chosen for a study area. The image data for the project were collected using the Earth Resources Laboratory's thematic mapper simulator (TMS) instrument.

  2. Image enhancement by spectral-error correction for dual-energy computed tomography.

    Science.gov (United States)

    Park, Kyung-Kook; Oh, Chang-Hyun; Akay, Metin

    2011-01-01

    Dual-energy CT (DECT) was reintroduced recently to use the additional spectral information of X-ray attenuation and aims for accurate density measurement and material differentiation. However, the spectral information lies in the difference between low and high energy images or measurements, so that it is difficult to acquire accurate spectral information due to amplification of high pixel noise in the resulting difference image. In this work, an image enhancement technique for DECT is proposed, based on the fact that the attenuation of a higher density material decreases more rapidly as X-ray energy increases. We define as spectral error the case when a pixel pair of low and high energy images deviates far from the expected attenuation trend. After analyzing the spectral-error sources of DECT images, we propose a DECT image enhancement method, which consists of three steps: water-reference offset correction, spectral-error correction, and anti-correlated noise reduction. It is the main idea of this work that makes spectral errors distributed like random noise over the true attenuation and suppressed by the well-known anti-correlated noise reduction. The proposed method suppressed noise of liver lesions and improved contrast between liver lesions and liver parenchyma in DECT contrast-enhanced abdominal images and their two-material decomposition.

  3. Purple Sweet Potato Color Ameliorates Cognition Deficits and Attenuates Oxidative Damage and Inflammation in Aging Mouse Brain Induced by D-Galactose

    Directory of Open Access Journals (Sweden)

    Qun Shan

    2009-01-01

    Full Text Available Purple sweet potato color (PSPC, a naturally occurring anthocyanin, has a powerful antioxidant activity in vitro and in vivo. This study explores whether PSPC has the neuroprotective effect on the aging mouse brain induced by D-galactose (D-gal. The mice administrated with PSPC (100 mg/kg.day, 4 weeks, from 9th week via oral gavage showed significantly improved behavior performance in the open field and passive avoidance test compared with D-gal-treated mice (500 mg/kg.day, 8 weeks. We further investigate the mechanism involved in neuroprotective effects of PSPC on mouse brain. Interestingly, we found, PSPC decreased the expression level of glial fibrillary acidic protein (GFAP, inducible nitric oxide synthase (iNOS, and cyclooxygenase-2 (COX-2, inhibited nuclear translocation of nuclear factor-kappaB (NF-κB, increased the activity of copper/zinc superoxide dismutase (Cu/Zn-SOD and catalase (CAT, and reduced the content of malondialdehyde (MDA, respectively. Our data suggested that PSPC attenuated D-gal-induced cognitive impairment partly via enhancing the antioxidant and anti-inflammatory capacity.

  4. Reduction of Musical Noise in Spectral Subtraction Method Using Subframe Phase Randomization

    Energy Technology Data Exchange (ETDEWEB)

    Seok, J.W.; Bae, K.S. [Kyungpook National University, Taegu (Korea)

    1999-06-01

    The Subframe phase randomization method is applied to the spectral subtraction method to reduce the musical noise in nonvoicing region after speech enhancement. The musical noise in the spectral subtraction method is the result of the narrowband tonal components that appearing somewhat periodically in the spectrogram of unvoiced and silence regions. Thus each synthesis frame in nonvoicing region is divided into several subframes to broaden the narrowband spectrum, and then phases of silence and unvoiced regions are randomized to eliminate the tonal components in the spectrum while keeping the shape of the amplitude spectrum. Performance assessments based on visual inspection of spectrogram, objective measure, and informal subjective listening tests demonstrate the superiority of the proposed algorithm. (author). 7 refs., 5 figs.

  5. Spectral stability of shifted states on star graphs

    Science.gov (United States)

    Kairzhan, Adilbek; Pelinovsky, Dmitry E.

    2018-03-01

    We consider the nonlinear Schrödinger (NLS) equation with the subcritical power nonlinearity on a star graph consisting of N edges and a single vertex under generalized Kirchhoff boundary conditions. The stationary NLS equation may admit a family of solitary waves parameterized by a translational parameter, which we call the shifted states. The two main examples include (i) the star graph with even N under the classical Kirchhoff boundary conditions and (ii) the star graph with one incoming edge and N  -  1 outgoing edges under a single constraint on coefficients of the generalized Kirchhoff boundary conditions. We obtain the general counting results on the Morse index of the shifted states and apply them to the two examples. In the case of (i), we prove that the shifted states with even N ≥slant 4 are saddle points of the action functional which are spectrally unstable under the NLS flow. In the case of (ii), we prove that the shifted states with the monotone profiles in the N  -  1 edges are spectrally stable, whereas the shifted states with non-monotone profiles in the N  -  1 edges are spectrally unstable, the two families intersect at the half-soliton states which are spectrally stable but nonlinearly unstable under the NLS flow. Since the NLS equation on a star graph with shifted states can be reduced to the homogeneous NLS equation on an infinite line, the spectral instability of shifted states is due to the perturbations breaking this reduction. We give a simple argument suggesting that the spectrally stable shifted states in the case of (ii) are nonlinearly unstable under the NLS flow due to the perturbations breaking the reduction to the homogeneous NLS equation.

  6. Optical crosstalk reduction using Amplified Spontaneous Emission (ASE)

    NARCIS (Netherlands)

    Chen, H.; Fontaine, N.K.; Ryf, R.; Alvarado, J.C.; van Weerdenburg, J.A.A.; Amezcua-Correa, R.; Okonkwo, C.; Koonen, A.M.J.

    2018-01-01

    We employ spectrally filtered amplified spontaneous emission as the signal carrier and matched local oscillator to mitigate optical crosstalk. We demonstrate polarization crosstalk reduction in single-mode fiber transmission and modal crosstalk reduction over multimode fiber.

  7. Are coronae of late type stars made of solar-like structures? The Fx-HR diagram and the pressure-temperature correlation

    OpenAIRE

    Peres, G.; Orlando, S.; Reale, F.

    2004-01-01

    We show that stellar coronae can be composed of X-ray emitting structures like those in the solar corona, using a large set of ROSAT/PSPC observations of late-type-stars, and a large set of solar X-ray data collected with Yohkoh/SXT. We have considered data on the solar corona at various phases of the cycle and various kinds of X-ray coronal structures, from flares to the background corona. The surface flux (F_x) vs. spectral hardness ratio (HR) diagram is a fundamental tool for our study. We...

  8. Contrast Dose and Radiation Dose Reduction in Abdominal Enhanced Computerized Tomography Scans with Single-phase Dual-energy Spectral Computerized Tomography Mode for Children with Solid Tumors.

    Science.gov (United States)

    Yu, Tong; Gao, Jun; Liu, Zhi-Min; Zhang, Qi-Feng; Liu, Yong; Jiang, Ling; Peng, Yun

    2017-04-05

    Contrast dose and radiation dose reduction in computerized tomography (CT) scan for adult has been explored successfully, but there have been few studies on the application of low-concentration contrast in pediatric abdominal CT examinations. This was a feasibility study on the use of dual-energy spectral imaging and adaptive statistical iterative reconstruction (ASiR) for the reduction of radiation dose and iodine contrast dose in pediatric abdominal CT patients with solid tumors. Forty-five patients with solid tumors who had initial CT (Group B) and follow-up CT (Group A) after chemotherapy were enrolled. The initial diagnostic CT scan (Group B) was performed using the standard two-phase enhanced CT with 320 mgI/ml concentration contrast, and the follow-up scan (Group A) was performed using a single-phase enhanced CT at 45 s after the beginning of the 270 mgI/ml contrast injection using spectral mode. Forty percent ASiR was used for the images in Group B and monochromatic images with energy levels ≥60 keV in Group A. In addition, filtered back-projection (FBP) reconstruction was used for monochromatic images hounsfield unit (HU). The abdominal organs of Groups A and B had similar degrees of absolute and relative enhancement (t = 0.36 and -1.716 for liver, -0.153 and -1.546 for pancreas, and 2.427 and 0.866 for renal cortex, all P> 0.05). Signal-to-noise ratio of the abdominal organs was significantly lower in Group A than in Group B (t = -8.11 for liver, -7.83 for pancreas, and -5.38 for renal cortex, all P 3, indicating clinically acceptable image quality. Single-phase, dual-energy spectral CT used for children with solid abdominal tumors can reduce contrast dose and radiation dose and can also maintain clinically acceptable image quality.

  9. Spectral gamuts and spectral gamut mapping

    Science.gov (United States)

    Rosen, Mitchell R.; Derhak, Maxim W.

    2006-01-01

    All imaging devices have two gamuts: the stimulus gamut and the response gamut. The response gamut of a print engine is typically described in CIE colorimetry units, a system derived to quantify human color response. More fundamental than colorimetric gamuts are spectral gamuts, based on radiance, reflectance or transmittance units. Spectral gamuts depend on the physics of light or on how materials interact with light and do not involve the human's photoreceptor integration or brain processing. Methods for visualizing a spectral gamut raise challenges as do considerations of how to utilize such a data-set for producing superior color reproductions. Recent work has described a transformation of spectra reduced to 6-dimensions called LabPQR. LabPQR was designed as a hybrid space with three explicit colorimetric axes and three additional spectral reconstruction axes. In this paper spectral gamuts are discussed making use of LabPQR. Also, spectral gamut mapping is considered in light of the colorimetric-spectral duality of the LabPQR space.

  10. Resolvent-based feedback control for turbulent friction drag reduction

    Science.gov (United States)

    Kawagoe, Aika; Nakashima, Satoshi; Luhar, Mitul; Fukagata, Koji

    2017-11-01

    Suboptimal control for turbulent friction drag reduction has been studied extensively. Nakashima et al. (accepted) extended resolvent analysis to suboptimal control, and for the control where the streamwise wall shear stress is used as an input (Case ST), they revealed the control effect across spectral space is mixed: there are regions of drag increase as well as reduction. This suggests that control performance may be improved if the control is applied for selective wavelengths, or if a new law is designed to suppress the spectral region leading to drag increase. In the present study, we first assess the effect of suboptimal control for selective wavelengths via DNS. The friction Reynolds number is set at 180. For Case ST, resolvent analysis predicts drag reduction at long streamwise wavelengths. DNS with control applied only for this spectral region, however, did not result in drag reduction. Then, we seek an effective control law using resolvent analysis and propose a new law. DNS results for this law are consistent with predictions from resolvent analysis, and about 10% drag reduction is attained. Further, we discuss how this law reduces the drag from a dynamical and theoretical point of view. This work was supported through Grant-in-Aid for Scientic Research (C) (No. 25420129) by Japan Society for the Promotion of Science (JSPS).

  11. Chandra Cluster Cosmology Project. II. Samples and X-Ray Data Reduction

    DEFF Research Database (Denmark)

    Vikhlinin, A.; Burenin, R. A.; Ebeling, H.

    2009-01-01

    We discuss the measurements of the galaxy cluster mass functions at z ≈ 0.05 and z ≈ 0.5 using high-quality Chandra observations of samples derived from the ROSAT PSPC All-Sky and 400 deg2 surveys. We provide a full reference for the data analysis procedures, present updated calibration of relati...... at a fixed mass threshold, e.g., by a factor of 5.0 ± 1.2 at M 500 = 2.5 × 1014 h –1 M sun between z = 0 and 0.5. This evolution reflects the growth of density perturbations, and can be used for the cosmological constraints complementing those from the distance-redshift relation....

  12. Impact of spectral nudging and domain size in studies of RCM response to parameter modification

    Energy Technology Data Exchange (ETDEWEB)

    Separovic, Leo; Laprise, Rene [Universite du Quebec a Montreal, Centre pour l' Etude et la Simulation du Climat a l' Echelle Regionale (ESCER), Montreal, QC (Canada); Universite du Quebec a Montreal (UQAM), Montreal, QC (Canada); Elia, Ramon de [Universite du Quebec a Montreal, Centre pour l' Etude et la Simulation du Climat a l' Echelle Regionale (ESCER), Montreal, QC (Canada); Consortium Ouranos, Montreal, QC (Canada)

    2012-04-15

    The paper aims at finding an RCM configuration that facilitates studies devoted to quantifying RCM response to parameter modification. When using short integration times, the response of the time-averaged variables to RCM modification tend to be blurred by the noise originating in the lack of predictability of the instantaneous atmospheric states. Two ways of enhancing the signal-to-noise ratio are studied in this work: spectral nudging and reduction of the computational domain size. The approach followed consists in the analysis of the sensitivity of RCM-simulated seasonal averages to perturbations of two parameters controlling deep convection and stratiform condensation, perturbed one at a time. Sensitivity is analyzed within different simulation configurations obtained by varying domain size and using the spectral nudging option. For each combination of these factors multiple members of identical simulations that differ exclusively in initial conditions are also generated to provide robust estimates of the sensitivities (the signal) and sample the noise. Results show that the noise magnitude is decreased both by reduction of domain size and the spectral nudging. However, the reduction of domain size alters some sensitivity signals. When spectral nudging is used significant alterations of the signal are not found. (orig.)

  13. X-ray Spectral Survey of WGACAT Quasars, II: Optical and Radio Properties of Quasars with Low Energy X-ray Cut-offs

    OpenAIRE

    Elvis, Martin; Fiore, Fabrizio; Giommi, Paolo; Padovani, Paolo

    1997-01-01

    We have selected quasars with X-ray colors suggestive of a low energy cut-off, from the ROSAT PSPC pointed archive. We examine the radio and optical properties of these 13 quasars. Five out of the seven quasars with good optical spectra show associated optical absorption lines, with two having high delta-v candidate systems. Two other cut-off quasars show reddening associated with the quasar. We conclude that absorption is highly likely to be the cause of the X-ray cut-offs, and that the abso...

  14. QEEG Spectral and Coherence Assessment of Autistic Children in Three Different Experimental Conditions

    Science.gov (United States)

    Machado, Calixto; Estévez, Mario; Leisman, Gerry; Melillo, Robert; Rodríguez, Rafael; DeFina, Phillip; Hernández, Adrián; Pérez-Nellar, Jesús; Naranjo, Rolando; Chinchilla, Mauricio; Garófalo, Nicolás; Vargas, José; Beltrán, Carlos

    2015-01-01

    We studied autistics by quantitative EEG spectral and coherence analysis during three experimental conditions: basal, watching a cartoon with audio (V-A), and with muted audio band (VwA). Significant reductions were found for the absolute power spectral density (PSD) in the central region for delta and theta, and in the posterior region for sigma…

  15. Purple sweet potato color alleviates D-galactose-induced brain aging in old mice by promoting survival of neurons via PI3K pathway and inhibiting cytochrome C-mediated apoptosis.

    Science.gov (United States)

    Lu, Jun; Wu, Dong-mei; Zheng, Yuan-lin; Hu, Bin; Zhang, Zi-feng

    2010-05-01

    Purple sweet potato color (PSPC), a class of naturally occurring anthocyanins, protects brain function against oxidative stress induced by D-galactose (D-gal) (Sigma-Aldrich, St. Louis, MO, USA). Our data showed that PSPC enhanced open-field activity, decreased step-through latency, and improved spatial learning and memory ability in D-gal-treated old mice by decreasing advanced glycation end-products' (AGEs) formation and the AGE receptor (RAGE) expression, and by elevating Cu,Zn-superoxide dismutase (Cu,Zn-SOD) (Sigma-Aldrich) and catalase (CAT) expression and activity. Cleavage of caspase-3 and increased terminal deoxynucleotidyl transferase (TdT)-mediated deoxyuridine triphosphate (dUTP) nick-end-labeling (TUNEL)-positive cells in D-gal-treated old mice were inhibited by PSPC, which might be attributed to its antioxidant property. PSPC also suppressed the activation of c-Jun NH(2)-terminal kinase (JNK) and the release of cytochrome c from mitochondria that counteracted the onset of neuronal apoptosis in D-gal-treated old mice. Furthermore, it was demonstrated that phosphoinositide 3-kinase (PI3K) activation was required for PSPC to promote the neuronal survival accompanied with phosphorylation and activation of Akt and p44/42 mitogen-activated protein kinase (MAPK) by using PI3K inhibitor LY294002 (Cell Signaling Technology, Inc., Beverly, MA, USA), implicating a neuronal survival mechanism. The present results suggest that neuronal survival promoted by PSPC may be a potentially effective method to enhance resistance of neurons to age-related disease.

  16. Spectral characterization and DNA binding properties of lanthanide(III)

    African Journals Online (AJOL)

    Spectral data of complexes suggest that the ligand binds metal ion through pyridine- nitrogen, azomethine-nitrogen and amido-oxygen donor atoms. Electrochemical behaviour of metal complexes was investigated by using cyclic voltammetry. The complexes undergo quasi-reversible one electron reduction. The binding ...

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

    Science.gov (United States)

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

    2009-11-01

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

  18. Reduction of variance in spectral estimates for correction of ultrasonic aberration.

    Science.gov (United States)

    Astheimer, Jeffrey P; Pilkington, Wayne C; Waag, Robert C

    2006-01-01

    A variance reduction factor is defined to describe the rate of convergence and accuracy of spectra estimated from overlapping ultrasonic scattering volumes when the scattering is from a spatially uncorrelated medium. Assuming that the individual volumes are localized by a spherically symmetric Gaussian window and that centers of the volumes are located on orbits of an icosahedral rotation group, the factor is minimized by adjusting the weight and radius of each orbit. Conditions necessary for the application of the variance reduction method, particularly for statistical estimation of aberration, are examined. The smallest possible value of the factor is found by allowing an unlimited number of centers constrained only to be within a ball rather than on icosahedral orbits. Computations using orbits formed by icosahedral vertices, face centers, and edge midpoints with a constraint radius limited to a small multiple of the Gaussian width show that a significant reduction of variance can be achieved from a small number of centers in the confined volume and that this reduction is nearly the maximum obtainable from an unlimited number of centers in the same volume.

  19. Yeast Interacting Proteins Database: YOL069W, YNL086W [Yeast Interacting Proteins Database

    Lifescience Database Archive (English)

    Full Text Available complex (Ndc80p-Nuf2p-Spc24p-Spc25p); involved in chromosome segregation, spindle checkpoint activity and kinetochore clustering...ved in chromosome segregation, spindle checkpoint activity and kinetochore clustering Rows with this bait as

  20. Evaluation of Clipping Based Iterative PAPR Reduction Techniques for FBMC Systems

    Directory of Open Access Journals (Sweden)

    Zsolt Kollár

    2014-01-01

    to conventional orthogonal frequency division multiplexing (OFDM technique. The low ACLR of the transmitted FBMC signal makes it especially favorable in cognitive radio applications, where strict requirements are posed on out-of-band radiation. Large dynamic range resulting in high peak-to-average power ratio (PAPR is characteristic of all sorts of multicarrier signals. The advantageous spectral properties of the high-PAPR FBMC signal are significantly degraded if nonlinearities are present in the transceiver chain. Spectral regrowth may appear, causing harmful interference in the neighboring frequency bands. This paper presents novel clipping based PAPR reduction techniques, evaluated and compared by simulations and measurements, with an emphasis on spectral aspects. The paper gives an overall comparison of PAPR reduction techniques, focusing on the reduction of the dynamic range of FBMC signals without increasing out-of-band radiation. An overview is presented on transmitter oriented techniques employing baseband clipping, which can maintain the system performance with a desired bit error rate (BER.

  1. Spectral integration in speech and non-speech sounds

    Science.gov (United States)

    Jacewicz, Ewa

    2005-04-01

    Spectral integration (or formant averaging) was proposed in vowel perception research to account for the observation that a reduction of the intensity of one of two closely spaced formants (as in /u/) produced a predictable shift in vowel quality [Delattre et al., Word 8, 195-210 (1952)]. A related observation was reported in psychoacoustics, indicating that when the components of a two-tone periodic complex differ in amplitude and frequency, its perceived pitch is shifted toward that of the more intense tone [Helmholtz, App. XIV (1875/1948)]. Subsequent research in both fields focused on the frequency interval that separates these two spectral components, in an attempt to determine the size of the bandwidth for spectral integration to occur. This talk will review the accumulated evidence for and against spectral integration within the hypothesized limit of 3.5 Bark for static and dynamic signals in speech perception and psychoacoustics. Based on similarities in the processing of speech and non-speech sounds, it is suggested that spectral integration may reflect a general property of the auditory system. A larger frequency bandwidth, possibly close to 3.5 Bark, may be utilized in integrating acoustic information, including speech, complex signals, or sound quality of a violin.

  2. On single-time reduction in quantum field theory

    International Nuclear Information System (INIS)

    Arkhipov, A.A.

    1984-01-01

    It is shown, how the causality and spectrality properties in qUantum field theory may help one to carry out a single-time reduction of the Bethe-Salpeter wave fUnction. The single-time reduction technique is not based on any concrete model of the quantum field theory. Axiomatic formulations underline the quantum field theory

  3. Spectral/ hp element methods: Recent developments, applications, and perspectives

    Science.gov (United States)

    Xu, Hui; Cantwell, Chris D.; Monteserin, Carlos; Eskilsson, Claes; Engsig-Karup, Allan P.; Sherwin, Spencer J.

    2018-02-01

    The spectral/ hp element method combines the geometric flexibility of the classical h-type finite element technique with the desirable numerical properties of spectral methods, employing high-degree piecewise polynomial basis functions on coarse finite element-type meshes. The spatial approximation is based upon orthogonal polynomials, such as Legendre or Chebychev polynomials, modified to accommodate a C 0 - continuous expansion. Computationally and theoretically, by increasing the polynomial order p, high-precision solutions and fast convergence can be obtained and, in particular, under certain regularity assumptions an exponential reduction in approximation error between numerical and exact solutions can be achieved. This method has now been applied in many simulation studies of both fundamental and practical engineering flows. This paper briefly describes the formulation of the spectral/ hp element method and provides an overview of its application to computational fluid dynamics. In particular, it focuses on the use of the spectral/ hp element method in transitional flows and ocean engineering. Finally, some of the major challenges to be overcome in order to use the spectral/ hp element method in more complex science and engineering applications are discussed.

  4. ROSAT Energy Spectra of Low-Mass X-Ray Binaries

    Science.gov (United States)

    Schulz, N. S.

    1999-01-01

    The 0.1-2.4 keV bandpass of the ROSAT Position Sensitive Proportional Counter (PSPC) offers an opportunity to study the very soft X-ray continuum of bright low-mass X-ray binaries (LMXBs). In 46 pointed observations, 23 LMXBs were observed with count rates between 0.4 and 165.4 counts s-1. The survey identified a total of 29 different luminosity levels, which are compared with observations and identified spectral states from other missions. The atoll source 4U 1705-44 was observed near Eddington luminosities in an unusually high intensity state. Spectral analysis provided a measure of the interstellar column density for all 49 observations. The sensitivity of spectral fits depends strongly on column density. Fits to highly absorbed spectra are merely insensitive toward any particular spectral model. Sources with column densities well below 1022 cm-2 are best fitted by power laws, while the blackbody model gives clearly worse fits to the data. Most single-component fits from sources with low column densities, however, are not acceptable at all. The inclusion of a blackbody component in eight sources can improve the fits significantly. The obtained emission radii of less than 5 km suggest emission from the neutron star surface. In 10 sources acceptable fits can only be achieved by including soft-line components. With a spectral resolution of the PSPC of 320-450 eV, between 0.6 and 1.2 keV unresolved broad-line features were detected around 0.65, 0.85, and 1.0 keV. The line fluxes range within 10-11 and 10-12 ergs cm-2 s-1, with equivalent widths between 24 and 210 eV. In LMC X-2, 2S 0918-549, and 4U 1254-690, line emission is indicated for the first time. The soft emission observed in 4U 0614+091 compares with recent ASCA results, with a new feature indicated at 1.31 keV. The deduced line fluxes in 4U 1820-30 and Cyg X-2 showed variability of a factor of 2 within timescales of 1-2 days. Average fluxes of line components in 4U 1820-30 varied by the same factor over a

  5. Yeast Interacting Proteins Database: YOL069W, YMR294W [Yeast Interacting Proteins Database

    Lifescience Database Archive (English)

    Full Text Available complex (Ndc80p-Nuf2p-Spc24p-Spc25p); involved in chromosome segregation, spindle checkpoint activity and kinetochore clustering...heckpoint activity and kinetochore clustering Rows with this bait as bait Rows with this bait as bait (3) Ro

  6. Kinetics of vinyl acetate emulsion polymerization in a pulsed tubular reactor: comparison between experimental and simulation results

    Directory of Open Access Journals (Sweden)

    Sayer C.

    2002-01-01

    Full Text Available A new reactor, the pulsed sieve plate column (PSPC, was developed to perform continuous emulsion polymerization reactions. This reactor combines the enhanced flexibility of tubular reactors with the mixing behavior provided by sieved plates and by the introduction of pulses that is important to prevent emulsion destabilization. The main objective of this work is to study the kinetics of vinyl acetate (VA emulsion polymerization reactions performed in this PSPC. Therefore, both experimental studies and reaction simulations were performed. Results showed that it is possible to obtain high conversions with rather low residence times in the PSPC.

  7. Spectral Characteristics of Salinized Soils during Microbial Remediation Processes.

    Science.gov (United States)

    Ma, Chuang; Shen, Guang-rong; Zhi, Yue-e; Wang, Zi-jun; Zhu, Yun; Li, Xian-hua

    2015-09-01

    In this study, the spectral reflectance of saline soils, the associated soil salt content (SSC) and the concentrations of salt ions were measured and analysed by tracing the container microbial remediation experiments for saline soil (main salt is sodium chloride) of Dongying City, Shandong Province. The sensitive spectral reflectance bands of saline soils to SSC, Cl- and Na+ in the process of microbial remediation were analysed. The average-dimension reduction of these bands was conducted by using a combination of correlation coefficient and decision coefficient, and by gradually narrowing the sampling interval method. Results showed that the tendency and magnitude of the average spectral reflectance in all bands of saline soils during the total remediation processes were nearly consistent with SSC and with Cl- coocentration, respectively. The degree of salinity of the soil, including SSC and salt ion concentrations, had a significant positive correlation with the spectral reflectance of all bands, particularly in the near-infrared band. The optimal spectral bands of SSC were 1370 to 1445 nm and 1447 to 1608 nm, whereas the optimal spectral bands of Cl- and Na+ were 1336 to 1461 nm and 1471 to 1561 nm, respectively. The relationship model among SSC, soil salt ion concentrations (Cl- and Na+) and soil spectral reflectance of the corresponding optimal spectral band was established. The largest R2 of relationship model between SSC and the average reflectance of associated optimal band reached to 0.95, and RMSEC and RMSEP were 1.076 and 0.591, respectively. Significant statistical analysis of salt factors and soil reflectance for different microbial remediation processes indicated that the spectral response characteristics and sensitivity of SSC to soil reflectance, which implied the feasibility of high spectrum test on soil microbial remediation monitoring, also provided the basis for quick nondestructive monitoring soil bioremediation process by soil spectral

  8. Spectral analysis of mammographic images using a multitaper method

    International Nuclear Information System (INIS)

    Wu Gang; Mainprize, James G.; Yaffe, Martin J.

    2012-01-01

    Purpose: Power spectral analysis in radiographic images is conventionally performed using a windowed overlapping averaging periodogram. This study describes an alternative approach using a multitaper technique and compares its performance with that of the standard method. This tool will be valuable in power spectrum estimation of images, whose content deviates significantly from uniform white noise. The performance of the multitaper approach will be evaluated in terms of spectral stability, variance reduction, bias, and frequency precision. The ultimate goal is the development of a useful tool for image quality assurance. Methods: A multitaper approach uses successive data windows of increasing order. This mitigates spectral leakage allowing one to calculate a reduced-variance power spectrum. The multitaper approach will be compared with the conventional power spectrum method in several typical situations, including the noise power spectra (NPS) measurements of simulated projection images of a uniform phantom, NPS measurement of real detector images of a uniform phantom for two clinical digital mammography systems, and the estimation of the anatomic noise in mammographic images (simulated images and clinical mammograms). Results: Examination of spectrum variance versus frequency resolution and bias indicates that the multitaper approach is superior to the conventional single taper methods in the prevention of spectrum leakage and variance reduction. More than four times finer frequency precision can be achieved with equivalent or less variance and bias. Conclusions: Without any shortening of the image data length, the bias is smaller and the frequency resolution is higher with the multitaper method, and the need to compromise in the choice of regions of interest size to balance between the reduction of variance and the loss of frequency resolution is largely eliminated.

  9. Optical network scaling: roles of spectral and spatial aggregation.

    Science.gov (United States)

    Arık, Sercan Ö; Ho, Keang-Po; Kahn, Joseph M

    2014-12-01

    As the bit rates of routed data streams exceed the throughput of single wavelength-division multiplexing channels, spectral and spatial traffic aggregation become essential for optical network scaling. These aggregation techniques reduce network routing complexity by increasing spectral efficiency to decrease the number of fibers, and by increasing switching granularity to decrease the number of switching components. Spectral aggregation yields a modest decrease in the number of fibers but a substantial decrease in the number of switching components. Spatial aggregation yields a substantial decrease in both the number of fibers and the number of switching components. To quantify routing complexity reduction, we analyze the number of multi-cast and wavelength-selective switches required in a colorless, directionless and contentionless reconfigurable optical add-drop multiplexer architecture. Traffic aggregation has two potential drawbacks: reduced routing power and increased switching component size.

  10. The Infrared Telescope Facility (IRTF) Spectral Library: Cool Stars

    Science.gov (United States)

    Rayner, John T.; Cushing, Michael C.; Vacca, William D.

    2009-12-01

    We present a 0.8-5 μm spectral library of 210 cool stars observed at a resolving power of R ≡ λ/Δλ ~ 2000 with the medium-resolution infrared spectrograph, SpeX, at the 3.0 m NASA Infrared Telescope Facility (IRTF) on Mauna Kea, Hawaii. The stars have well-established MK spectral classifications and are mostly restricted to near-solar metallicities. The sample not only contains the F, G, K, and M spectral types with luminosity classes between I and V, but also includes some AGB, carbon, and S stars. In contrast to some other spectral libraries, the continuum shape of the spectra is measured and preserved in the data reduction process. The spectra are absolutely flux calibrated using the Two Micron All Sky Survey photometry. Potential uses of the library include studying the physics of cool stars, classifying and studying embedded young clusters and optically obscured regions of the Galaxy, evolutionary population synthesis to study unresolved stellar populations in optically obscured regions of galaxies and synthetic photometry. The library is available in digital form from the IRTF Web site.

  11. Quantifying metal artefact reduction using virtual monochromatic dual-layer detector spectral CT imaging in unilateral and bilateral total hip prostheses

    Energy Technology Data Exchange (ETDEWEB)

    Wellenberg, R.H.H., E-mail: r.h.wellenberg@amc.uva.nl [Department of Radiology, Academic Medical Centre, Amsterdam (Netherlands); Boomsma, M.F., E-mail: m.f.boomsma@isala.nl [Department of Radiology, Isala, Zwolle (Netherlands); Osch, J.A.C. van, E-mail: j.a.c.van.osch@isala.nl [Department of Radiology, Isala, Zwolle (Netherlands); Vlassenbroek, A., E-mail: alain.vlassenbroek@philips.com [Philips Medical Systems, Brussels (Belgium); Milles, J., E-mail: julien.milles@philips.com [Philips Medical Systems, Eindhoven (Netherlands); Edens, M.A., E-mail: m.a.edens@isala.nl [Department of Innovation and Science, Isala, Zwolle (Netherlands); Streekstra, G.J., E-mail: g.j.streekstra@amc.uva.nl [Department of Radiology, Academic Medical Centre, Amsterdam (Netherlands); Slump, C.H., E-mail: c.h.slump@utwente.nl [MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede (Netherlands); Maas, M., E-mail: m.maas@amc.uva.nl [Department of Radiology, Academic Medical Centre, Amsterdam (Netherlands)

    2017-03-15

    Highlights: • Dual-layer detector CT reduces metal artefacts at high monochromatic energies (keV). • 130 keV images were optimal based on quantitative analysis on CNRs. • Optimal keVs varied from 74 to 150 keV for different hip prostheses configurations. • The Titanium alloy resulted in less severe artefacts compared to the Cobalt alloy. • Severe metal artefacts, caused by extensive photon-starvation, were not reduced. - Abstract: Purpose: To quantify the impact of prosthesis material and design on the reduction of metal artefacts in total hip arthroplasties using virtual monochromatic dual-layer detector Spectral CT imaging. Methods: The water-filled total hip arthroplasty phantom was scanned on a novel 128-slice Philips IQon dual-layer detector Spectral CT scanner at 120-kVp and 140-kVp at a standard computed tomography dose index of 20.0 mGy. Several unilateral and bilateral hip prostheses consisting of different metal alloys were inserted and combined which were surrounded by 18 hydroxyapatite calcium carbonate pellets representing bone. Images were reconstructed with iterative reconstruction and analysed at monochromatic energies ranging from 40 to 200 keV. CT numbers in Hounsfield Units (HU), noise measured as the standard deviation in HU, signal-to-noise-ratios (SNRs) and contrast-to-noise-ratios (CNRs) were analysed within fixed regions-of-interests placed in and around the pellets. Results: In 70 and 74 keV virtual monochromatic images the CT numbers of the pellets were similar to 120-kVp and 140-kVp polychromatic results, therefore serving as reference. A separation into three categories of metal artefacts was made (no, mild/moderate and severe) where pellets were categorized based on HU deviations. At high keV values overall image contrast was reduced. For mild/moderate artefacts, the highest average CNRs were attained with virtual monochromatic 130 keV images, acquired at 140-kVp. Severe metal artefacts were not reduced. In 130 keV images

  12. Lesion characterization in spectral photon-counting tomosynthesis

    Science.gov (United States)

    Cederström, Björn; Fredenberg, Erik; Berggren, Karl; Erhard, Klaus; Danielsson, Mats; Wallis, Matthew

    2017-03-01

    It has previously been shown that 2D spectral mammography can be used to discriminate between (likely benign) cystic and (potentially malignant) solid lesions in order to reduce unnecessary recalls in mammography. One limitation of the technique is, however, that the composition of overlapping tissue needs to be interpolated from a region surrounding the lesion. The purpose of this investigation was to demonstrate that lesion characterization can be done with spectral tomosynthesis, and to investigate whether the 3D information available in tomosynthesis can reduce the uncertainty from the interpolation of surrounding tissue. A phantom experiment was designed to simulate a cyst and a tumor, where the tumor was overlaid with a structure that made it mimic a cyst. In 2D, the two targets appeared similar in composition, whereas spectral tomosynthesis revealed the exact compositional difference. However, the loss of discrimination signal due to spread from the plane of interest was of the same strength as the reduction of anatomical noise. Results from a preliminary investigation on clinical tomosynthesis images of solid lesions yielded results that were consistent with the phantom experiments, but were still to some extent inconclusive. We conclude that lesion characterization is feasible in spectral tomosynthesis, but more data, as well as refinement of the calibration and discrimination algorithms, are needed to draw final conclusions about the benefit compared to 2D.

  13. The role of spectral detail in the binaural transfer function on perceived externalization in a reverberant environment

    DEFF Research Database (Denmark)

    Hassager, Henrik Gert; Gran, Fredrik; Dau, Torsten

    2016-01-01

    . For various filter bandwidths, the modified BRIRs were convolved with broadband noise and listeners judged the perceived position of the noise when virtualized over headphones. Only reductions in spectral details of the direct part obtained with filter bandwidths broader than one equivalent rectangular...... bandwidth affected externalization. Reductions in spectral details of the reverberant part had only little influence on externalization. In both conditions, externalization was not as pronounced at 0° as at 50°. To characterize the auditory processes that may be involved in the perception of externalization...

  14. Object-based assessment of burn severity in diseased forests using high-spatial and high-spectral resolution MASTER airborne imagery

    Science.gov (United States)

    Chen, Gang; Metz, Margaret R.; Rizzo, David M.; Dillon, Whalen W.; Meentemeyer, Ross K.

    2015-04-01

    Forest ecosystems are subject to a variety of disturbances with increasing intensities and frequencies, which may permanently change the trajectories of forest recovery and disrupt the ecosystem services provided by trees. Fire and invasive species, especially exotic disease-causing pathogens and insects, are examples of disturbances that together could pose major threats to forest health. This study examines the impacts of fire and exotic disease (sudden oak death) on forests, with an emphasis on the assessment of post-fire burn severity in a forest where trees have experienced three stages of disease progression pre-fire: early-stage (trees retaining dried foliage and fine twigs), middle-stage (trees losing fine crown fuels), and late-stage (trees falling down). The research was conducted by applying Geographic Object-Based Image Analysis (GEOBIA) to MASTER airborne images that were acquired immediately following the fire for rapid assessment and contained both high-spatial (4 m) and high-spectral (50 bands) resolutions. Although GEOBIA has gradually become a standard tool for analyzing high-spatial resolution imagery, high-spectral resolution data (dozens to hundreds of bands) can dramatically reduce computation efficiency in the process of segmentation and object-based variable extraction, leading to complicated variable selection for succeeding modeling. Hence, we also assessed two widely used band reduction algorithms, PCA (principal component analysis) and MNF (minimum noise fraction), for the delineation of image objects and the subsequent performance of burn severity models using either PCA or MNF derived variables. To increase computation efficiency, only the top 5 PCA and MNF and top 10 PCA and MNF components were evaluated, which accounted for 10% and 20% of the total number of the original 50 spectral bands, respectively. Results show that if no band reduction was applied the models developed for the three stages of disease progression had relatively

  15. Understanding Soliton Spectral Tunneling as a Spectral Coupling Effect

    DEFF Research Database (Denmark)

    Guo, Hairun; Wang, Shaofei; Zeng, Xianglong

    2013-01-01

    Soliton eigenstate is found corresponding to a dispersive phase profile under which the soliton phase changes induced by the dispersion and nonlinearity are instantaneously counterbalanced. Much like a waveguide coupler relying on a spatial refractive index profile that supports mode coupling...... between channels, here we suggest that the soliton spectral tunneling effect can be understood supported by a spectral phase coupler. The dispersive wave number in the spectral domain must have a coupler-like symmetric profile for soliton spectral tunneling to occur. We show that such a spectral coupler...

  16. THE INFRARED TELESCOPE FACILITY (IRTF) SPECTRAL LIBRARY: COOL STARS

    International Nuclear Information System (INIS)

    Rayner, John T.; Cushing, Michael C.; Vacca, William D.

    2009-01-01

    We present a 0.8-5 μm spectral library of 210 cool stars observed at a resolving power of R ≡ λ/Δλ ∼ 2000 with the medium-resolution infrared spectrograph, SpeX, at the 3.0 m NASA Infrared Telescope Facility (IRTF) on Mauna Kea, Hawaii. The stars have well-established MK spectral classifications and are mostly restricted to near-solar metallicities. The sample not only contains the F, G, K, and M spectral types with luminosity classes between I and V, but also includes some AGB, carbon, and S stars. In contrast to some other spectral libraries, the continuum shape of the spectra is measured and preserved in the data reduction process. The spectra are absolutely flux calibrated using the Two Micron All Sky Survey photometry. Potential uses of the library include studying the physics of cool stars, classifying and studying embedded young clusters and optically obscured regions of the Galaxy, evolutionary population synthesis to study unresolved stellar populations in optically obscured regions of galaxies and synthetic photometry. The library is available in digital form from the IRTF Web site.

  17. Piecewise spectrally band-pass for compressive coded aperture spectral imaging

    International Nuclear Information System (INIS)

    Qian Lu-Lu; Lü Qun-Bo; Huang Min; Xiang Li-Bin

    2015-01-01

    Coded aperture snapshot spectral imaging (CASSI) has been discussed in recent years. It has the remarkable advantages of high optical throughput, snapshot imaging, etc. The entire spatial-spectral data-cube can be reconstructed with just a single two-dimensional (2D) compressive sensing measurement. On the other hand, for less spectrally sparse scenes, the insufficiency of sparse sampling and aliasing in spatial-spectral images reduce the accuracy of reconstructed three-dimensional (3D) spectral cube. To solve this problem, this paper extends the improved CASSI. A band-pass filter array is mounted on the coded mask, and then the first image plane is divided into some continuous spectral sub-band areas. The entire 3D spectral cube could be captured by the relative movement between the object and the instrument. The principle analysis and imaging simulation are presented. Compared with peak signal-to-noise ratio (PSNR) and the information entropy of the reconstructed images at different numbers of spectral sub-band areas, the reconstructed 3D spectral cube reveals an observable improvement in the reconstruction fidelity, with an increase in the number of the sub-bands and a simultaneous decrease in the number of spectral channels of each sub-band. (paper)

  18. High performance multi-spectral interrogation for surface plasmon resonance imaging sensors.

    Science.gov (United States)

    Sereda, A; Moreau, J; Canva, M; Maillart, E

    2014-04-15

    Surface plasmon resonance (SPR) sensing has proven to be a valuable tool in the field of surface interactions characterization, especially for biomedical applications where label-free techniques are of particular interest. In order to approach the theoretical resolution limit, most SPR-based systems have turned to either angular or spectral interrogation modes, which both offer very accurate real-time measurements, but at the expense of the 2-dimensional imaging capability, therefore decreasing the data throughput. In this article, we show numerically and experimentally how to combine the multi-spectral interrogation technique with 2D-imaging, while finding an optimum in terms of resolution, accuracy, acquisition speed and reduction in data dispersion with respect to the classical reflectivity interrogation mode. This multi-spectral interrogation methodology is based on a robust five parameter fitting of the spectral reflectivity curve which enables monitoring of the reflectivity spectral shift with a resolution of the order of ten picometers, and using only five wavelength measurements per point. In fine, such multi-spectral based plasmonic imaging system allows biomolecular interaction monitoring in a linear regime independently of variations of buffer optical index, which is illustrated on a DNA-DNA model case. © 2013 Elsevier B.V. All rights reserved.

  19. Influence of a polyphenol-enriched protein powder on exercise-induced inflammation and oxidative stress in athletes: a randomized trial using a metabolomics approach.

    Directory of Open Access Journals (Sweden)

    David C Nieman

    Full Text Available Polyphenol supplementation was tested as a countermeasure to inflammation and oxidative stress induced by 3-d intensified training.Water soluble polyphenols from blueberry and green tea extracts were captured onto a polyphenol soy protein complex (PSPC. Subjects were recruited, and included 38 long-distance runners ages 19-45 years who regularly competed in road races. Runners successfully completing orientation and baseline testing (N = 35 were randomized to 40 g/d PSPC (N = 17 (2,136 mg/d gallic acid equivalents or placebo (N = 18 for 17 d using double-blinded methods and a parallel group design, with a 3-d running period inserted at day 14 (2.5 h/d, 70% VO2max. Blood samples were collected pre- and post-14 d supplementation, and immediately and 14 h after the third day of running in subjects completing all aspects of the study (N = 16 PSPC, N = 15 placebo, and analyzed using a metabolomics platform with GC-MS and LC-MS.Metabolites characteristic of gut bacteria metabolism of polyphenols were increased with PSPC and 3 d running (e.g., hippurate, 4-hydroxyhippurate, 4-methylcatechol sulfate, 1.8-, 1.9-, 2.5-fold, respectively, P<0.05, an effect which persisted for 14-h post-exercise. Fatty acid oxidation and ketogenesis were induced by exercise in both groups, with more ketones at 14-h post-exercise in PSPC (3-hydroxybutyrate, 1.8-fold, P<0.05. Established biomarkers for inflammation (CRP, cytokines and oxidative stress (protein carbonyls did not differ between groups.PSPC supplementation over a 17-d period did not alter established biomarkers for inflammation and oxidative stress but was linked to an enhanced gut-derived phenolic signature and ketogenesis in runners during recovery from 3-d heavy exertion.ClinicalTrials.gov, U.S. National Institutes of Health, identifier: NCT01775384.

  20. Measurement and analysis of neutron flux distribution of STACY heterogeneous core by position sensitive proportional counter. Contract research

    Energy Technology Data Exchange (ETDEWEB)

    Murazaki, Minoru; Uno, Yuichi; Miyoshi, Yoshinori [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2003-03-01

    We have measured neutron flux distribution around the core tank of STACY heterogeneous core by position sensitive proportional counter (PSPC) to develop the method to measure reactivity for subcritical systems. The neutron flux distribution data in the position accuracy of {+-}13 mm have been obtained in the range of uranium concentration of 50g/L to 210g/L both in critical and in subcritical state. The prompt neutron decay constant, {alpha}, was evaluated from the measurement data of pulsed neutron source experiments. We also calculated distribution of neutron flux and {sup 3}He reaction rates at the location of PSPC by using continuous energy Monte Carlo code MCNP. The measurement data was compared with the calculation results. As results of comparison, calculated values agreed generally with measurement data of PSPC with Cd cover in the region above half of solution height, but the difference between calculated value and measurement data was large in the region below half of solution height. On the other hand, calculated value agreed well with measurement data of PSPC without Cd cover. (author)

  1. Spectrum-to-Spectrum Searching Using a Proteome-wide Spectral Library*

    Science.gov (United States)

    Yen, Chia-Yu; Houel, Stephane; Ahn, Natalie G.; Old, William M.

    2011-01-01

    The unambiguous assignment of tandem mass spectra (MS/MS) to peptide sequences remains a key unsolved problem in proteomics. Spectral library search strategies have emerged as a promising alternative for peptide identification, in which MS/MS spectra are directly compared against a reference library of confidently assigned spectra. Two problems relate to library size. First, reference spectral libraries are limited to rediscovery of previously identified peptides and are not applicable to new peptides, because of their incomplete coverage of the human proteome. Second, problems arise when searching a spectral library the size of the entire human proteome. We observed that traditional dot product scoring methods do not scale well with spectral library size, showing reduction in sensitivity when library size is increased. We show that this problem can be addressed by optimizing scoring metrics for spectrum-to-spectrum searches with large spectral libraries. MS/MS spectra for the 1.3 million predicted tryptic peptides in the human proteome are simulated using a kinetic fragmentation model (MassAnalyzer version2.1) to create a proteome-wide simulated spectral library. Searches of the simulated library increase MS/MS assignments by 24% compared with Mascot, when using probabilistic and rank based scoring methods. The proteome-wide coverage of the simulated library leads to 11% increase in unique peptide assignments, compared with parallel searches of a reference spectral library. Further improvement is attained when reference spectra and simulated spectra are combined into a hybrid spectral library, yielding 52% increased MS/MS assignments compared with Mascot searches. Our study demonstrates the advantages of using probabilistic and rank based scores to improve performance of spectrum-to-spectrum search strategies. PMID:21532008

  2. Nonlocal low-rank and sparse matrix decomposition for spectral CT reconstruction

    Science.gov (United States)

    Niu, Shanzhou; Yu, Gaohang; Ma, Jianhua; Wang, Jing

    2018-02-01

    Spectral computed tomography (CT) has been a promising technique in research and clinics because of its ability to produce improved energy resolution images with narrow energy bins. However, the narrow energy bin image is often affected by serious quantum noise because of the limited number of photons used in the corresponding energy bin. To address this problem, we present an iterative reconstruction method for spectral CT using nonlocal low-rank and sparse matrix decomposition (NLSMD), which exploits the self-similarity of patches that are collected in multi-energy images. Specifically, each set of patches can be decomposed into a low-rank component and a sparse component, and the low-rank component represents the stationary background over different energy bins, while the sparse component represents the rest of the different spectral features in individual energy bins. Subsequently, an effective alternating optimization algorithm was developed to minimize the associated objective function. To validate and evaluate the NLSMD method, qualitative and quantitative studies were conducted by using simulated and real spectral CT data. Experimental results show that the NLSMD method improves spectral CT images in terms of noise reduction, artifact suppression and resolution preservation.

  3. UniPOPS: Unified data reduction suite

    Science.gov (United States)

    Maddalena, Ronald J.; Garwood, Robert W.; Salter, Christopher J.; Stobie, Elizabeth B.; Cram, Thomas R.; Morgan, Lorrie; Vance, Bob; Hudson, Jerome

    2015-03-01

    UniPOPS, a suite of programs and utilities developed at the National Radio Astronomy Observatory (NRAO), reduced data from the observatory's single-dish telescopes: the Tucson 12-m, the Green Bank 140-ft, and archived data from the Green Bank 300-ft. The primary reduction programs, 'line' (for spectral-line reduction) and 'condar' (for continuum reduction), used the People-Oriented Parsing Service (POPS) as the command line interpreter. UniPOPS unified previous analysis packages and provided new capabilities; development of UniPOPS continued within the NRAO until 2004 when the 12-m was turned over to the Arizona Radio Observatory (ARO). The submitted code is version 3.5 from 2004, the last supported by the NRAO.

  4. Impact of metal artifact reduction software on image quality of gemstone spectral imaging dual-energy cerebral CT angiography after intracranial aneurysm clipping

    Energy Technology Data Exchange (ETDEWEB)

    Dunet, Vincent; Bernasconi, Martine; Hajdu, Steven David; Meuli, Reto Antoine; Zerlauth, Jean-Baptiste [Lausanne University Hospital, Department of Diagnostic and Interventional Radiology, Lausanne (Switzerland); Daniel, Roy Thomas [Lausanne University Hospital, Department of Neurosurgery, Lausanne (Switzerland)

    2017-09-15

    We aimed to assess the impact of metal artifact reduction software (MARs) on image quality of gemstone spectral imaging (GSI) dual-energy (DE) cerebral CT angiography (CTA) after intracranial aneurysm clipping. This retrospective study was approved by the institutional review board, which waived patient written consent. From January 2013 to September 2016, single source DE cerebral CTA were performed in 45 patients (mean age: 60 ± 9 years, male 9) after intracranial aneurysm clipping and reconstructed with and without MARs. Signal-to-noise (SNR), contrast-to-noise (CNR), and relative CNR (rCNR) ratios were calculated from attenuation values measured in the internal carotid artery (ICA) and middle cerebral artery (MCA). Volume of clip and artifacts and relative clip blurring reduction (rCBR) ratios were also measured at each energy level with/without MARs. Variables were compared between GSI and GSI-MARs using the paired Wilcoxon signed-rank test. MARs significantly reduced metal artifacts at all energy levels but 130 and 140 keV, regardless of clips' location and number. The optimal rCBR was obtained at 110 and 80 keV, respectively, on GSI and GSI-MARs images, with up to 96% rCNR increase on GSI-MARs images. The best compromise between metal artifact reduction and rCNR was obtained at 70-75 and 65-70 keV for GSI and GSI-MARs images, respectively, with up to 15% rCBR and rCNR increase on GSI-MARs images. MARs significantly reduces metal artifacts on DE cerebral CTA after intracranial aneurysm clipping regardless of clips' location and number. It may be used to reduce radiation dose while increasing CNR. (orig.)

  5. Speech Enhancement by MAP Spectral Amplitude Estimation Using a Super-Gaussian Speech Model

    Directory of Open Access Journals (Sweden)

    Lotter Thomas

    2005-01-01

    Full Text Available This contribution presents two spectral amplitude estimators for acoustical background noise suppression based on maximum a posteriori estimation and super-Gaussian statistical modelling of the speech DFT amplitudes. The probability density function of the speech spectral amplitude is modelled with a simple parametric function, which allows a high approximation accuracy for Laplace- or Gamma-distributed real and imaginary parts of the speech DFT coefficients. Also, the statistical model can be adapted to optimally fit the distribution of the speech spectral amplitudes for a specific noise reduction system. Based on the super-Gaussian statistical model, computationally efficient maximum a posteriori speech estimators are derived, which outperform the commonly applied Ephraim-Malah algorithm.

  6. Michelson mode selector for spectral range stabilization in a self-sweeping fiber laser.

    Science.gov (United States)

    Tkachenko, A Yu; Vladimirskaya, A D; Lobach, I A; Kablukov, S I

    2018-04-01

    We report on spectral range stabilization in a self-sweeping laser by adding a narrowband fiber Bragg grating (FBG) to the output mirror in the Michelson configuration. The effects of FBG reflectivity and optical path difference in the Michelson interferometer on the laser spectral dynamics are investigated. Optimization of the interferometer allows us to demonstrate broadband (over 16 nm) self-sweeping operation and reduction of the start and stop wavelength fluctuations by two orders and one order of magnitude (∼100 and 15 times) for start and stop bounds, respectively (down to several picometers). The proposed approaches significantly improve quality of the spectral dynamics and facilitate application of the self-sweeping lasers.

  7. Power spectral analysis of heart rate in hyperthyroidism.

    Science.gov (United States)

    Cacciatori, V; Bellavere, F; Pezzarossa, A; Dellera, A; Gemma, M L; Thomaseth, K; Castello, R; Moghetti, P; Muggeo, M

    1996-08-01

    The aim of the present study was to evaluate the impact of hyperthyroidism on the cardiovascular system by separately analyzing the sympathetic and parasympathetic influences on heart rate. Heart rate variability was evaluated by autoregressive power spectral analysis. This method allows a reliable quantification of the low frequency (LF) and high frequency (HF) components of the heart rate power spectral density; these are considered to be under mainly sympathetic and pure parasympathetic control, respectively. In 10 newly diagnosed untreated hyperthyroid patients with Graves' disease, we analyzed power spectral density of heart rate cyclic variations at rest, while lying, and while standing. In addition, heart rate variations during deep breathing, lying and standing, and Valsalva's maneuver were analyzed. The results were compared to those obtained from 10 age-, sex-, and body mass index-matched control subjects. In 8 hyperthyroid patients, the same evaluation was repeated after the induction of stable euthyroidism by methimazole. Heart rate power spectral analysis showed a sharp reduction of HF components in hyperthyroid subjects compared to controls [lying, 13.3 +/- 4.1 vs. 32.0 +/- 5.6 normalized units (NU; P hyperthyroid subjects while both lying (11.3 +/- 4.5 vs. 3.5 +/- 1.1; P hyperthyroid patients than in controls (1.12 +/- 0.03 vs. 1.31 +/- 0.04; P activity and, thus, a relative hypersympathetic tone.

  8. Berkeley SuperNova Ia Program (BSNIP): Initial Spectral Analysis

    Science.gov (United States)

    Silverman, Jeffrey; Kong, J.; Ganeshalingam, M.; Li, W.; Filippenko, A. V.

    2011-01-01

    The Berkeley SuperNova Ia Program (BSNIP) has been observing nearby (z analysis of this dataset consists of accurately and robustly measuring the strength and position of various spectral features near maximum brightness. We determine the endpoints, pseudo-continuum, expansion velocity, equivalent width, and depth of each major feature observed in our wavelength range. For objects with multiple spectra near maximum brightness we investigate how these values change with time. From these measurements we also calculate velocity gradients and various flux ratios within a given spectrum which will allow us to explore correlations between spectral and photometric observables. Some possible correlations have been studied previously, but our dataset is unique in how self-consistent the data reduction and spectral feature measurements have been, and it is a factor of a few larger than most earlier studies. We will briefly summarize the contents of the full dataset as an introduction to our initial analysis. Some of our measurements of SN Ia spectral features, along with a few initial results from those measurements, will be presented. Finally, we will comment on our current progress and planned future work. We gratefully acknowledge the financial support of NSF grant AST-0908886, the TABASGO Foundation, and the Marc J. Staley Graduate Fellowship in Astronomy.

  9. Spectral evolution of GRBs with negative spectral lag using Fermi GBM observations

    Science.gov (United States)

    Chakrabarti, Arundhati; Chaudhury, Kishor; Sarkar, Samir K.; Bhadra, Arunava

    2018-06-01

    The positive spectral lag of Gamma Ray Bursts (GRBs) is often explained in terms of hard-to-soft spectral evolution of GRB pulses. While positive lags of GRBs is very common, there are few GRB pulses that exhibits negative spectral lags. In the present work we examine whether negative lags of GRBs also can be interpreted in terms of spectral evolution of GRB pulses or not. Using Fermi-GBM data, we identify two GRBs, GRB 090426C and GRB 150213A, with clean pulses that exhibit negative spectral lag. An indication of soft to hard transition has been noticed for the negative spectral lag events from the spectral evolution study. The implication of the present findings on the models of GRB spectral lags are discussed.

  10. Strong reduction of spectral heterogeneity in gold bipyramids for single-particle and single-molecule plasmon sensing.

    Science.gov (United States)

    Peters, S M E; Verheijen, M A; Prins, M W J; Zijlstra, P

    2016-01-15

    Single metal nanoparticles are attractive biomolecular sensors. Binding of analyte to a functional particle results in a plasmon shift that can be conveniently monitored in a far-field optical microscope. Heterogeneities in spectral properties of individual particles in an ensemble affect the reliability of a single-particle plasmon sensor, especially when plasmon shifts are monitored in real-time using a fixed irradiation wavelength. We compare the spectral heterogeneity of different plasmon sensor geometries (gold nanospheres, nanorods, and bipyramids) and correlate this to their size and aspect-ratio dispersion. We show that gold bipyramids exhibit a strongly reduced heterogeneity in aspect ratio and plasmon wavelength compared to commonly used gold nanorods. We show that this translates into a significantly improved homogeneity of the response to molecular binding without compromising single-molecule sensitivity.

  11. From spectral holeburning memory to spatial-spectral microwave signal processing

    International Nuclear Information System (INIS)

    Babbitt, Wm Randall; Barber, Zeb W; Harrington, Calvin; Mohan, R Krishna; Sharpe, Tia; Bekker, Scott H; Chase, Michael D; Merkel, Kristian D; Stiffler, Colton R; Traxinger, Aaron S; Woidtke, Alex J

    2014-01-01

    Many storage and processing systems based on spectral holeburning have been proposed that access the broad bandwidth and high dynamic range of spatial-spectral materials, but only recently have practical systems been developed that exceed the performance and functional capabilities of electronic devices. This paper reviews the history of the proposed applications of spectral holeburning and spatial-spectral materials, from frequency domain optical memory to microwave photonic signal processing systems. The recent results of a 20 GHz bandwidth high performance spectrum monitoring system with the additional capability of broadband direction finding demonstrates the potential for spatial-spectral systems to be the practical choice for solving demanding signal processing problems in the near future. (paper)

  12. An efficient spectral crystal plasticity solver for GPU architectures

    Science.gov (United States)

    Malahe, Michael

    2018-03-01

    We present a spectral crystal plasticity (CP) solver for graphics processing unit (GPU) architectures that achieves a tenfold increase in efficiency over prior GPU solvers. The approach makes use of a database containing a spectral decomposition of CP simulations performed using a conventional iterative solver over a parameter space of crystal orientations and applied velocity gradients. The key improvements in efficiency come from reducing global memory transactions, exposing more instruction-level parallelism, reducing integer instructions and performing fast range reductions on trigonometric arguments. The scheme also makes more efficient use of memory than prior work, allowing for larger problems to be solved on a single GPU. We illustrate these improvements with a simulation of 390 million crystal grains on a consumer-grade GPU, which executes at a rate of 2.72 s per strain step.

  13. Simulation of multivariate stationary stochastic processes using dimension-reduction representation methods

    Science.gov (United States)

    Liu, Zhangjun; Liu, Zenghui; Peng, Yongbo

    2018-03-01

    In view of the Fourier-Stieltjes integral formula of multivariate stationary stochastic processes, a unified formulation accommodating spectral representation method (SRM) and proper orthogonal decomposition (POD) is deduced. By introducing random functions as constraints correlating the orthogonal random variables involved in the unified formulation, the dimension-reduction spectral representation method (DR-SRM) and the dimension-reduction proper orthogonal decomposition (DR-POD) are addressed. The proposed schemes are capable of representing the multivariate stationary stochastic process with a few elementary random variables, bypassing the challenges of high-dimensional random variables inherent in the conventional Monte Carlo methods. In order to accelerate the numerical simulation, the technique of Fast Fourier Transform (FFT) is integrated with the proposed schemes. For illustrative purposes, the simulation of horizontal wind velocity field along the deck of a large-span bridge is proceeded using the proposed methods containing 2 and 3 elementary random variables. Numerical simulation reveals the usefulness of the dimension-reduction representation methods.

  14. Spectral Imaging by Upconversion

    DEFF Research Database (Denmark)

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

    2011-01-01

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

  15. Spectral analysis of an algebraic collapsing acceleration for the characteristics method

    International Nuclear Information System (INIS)

    Le Tellier, R.; Hebert, A.

    2005-01-01

    A spectral analysis of a diffusion synthetic acceleration called Algebraic Collapsing Acceleration (ACA) was carried out in the context of the characteristics method to solve the neutron transport equation. Two analysis were performed in order to assess the ACA performances. Both a standard Fourier analysis in a periodic and infinite slab-geometry and a direct spectral analysis for a finite slab-geometry were investigated. In order to evaluate its performance, ACA was compared with two competing techniques used to accelerate the convergence of the characteristics method, the Self-Collision Re-balancing technique and the Asymptotic Synthetic Acceleration. In the restricted framework of 1-dimensional slab-geometries, we conclude that ACA offers a good compromise between the reduction of the spectral radius of the iterative matrix and the resources to construct, store and solve the corrective system. A comparison on a monoenergetic 2-dimensional benchmark was performed and tends to confirm these conclusions. (authors)

  16. Examination of Spectral Transformations on Spectral Mixture Analysis

    Science.gov (United States)

    Deng, Y.; Wu, C.

    2018-04-01

    While many spectral transformation techniques have been applied on spectral mixture analysis (SMA), few study examined their necessity and applicability. This paper focused on exploring the difference between spectrally transformed schemes and untransformed scheme to find out which transformed scheme performed better in SMA. In particular, nine spectrally transformed schemes as well as untransformed scheme were examined in two study areas. Each transformed scheme was tested 100 times using different endmember classes' spectra under the endmember model of vegetation- high albedo impervious surface area-low albedo impervious surface area-soil (V-ISAh-ISAl-S). Performance of each scheme was assessed based on mean absolute error (MAE). Statistical analysis technique, Paired-Samples T test, was applied to test the significance of mean MAEs' difference between transformed and untransformed schemes. Results demonstrated that only NSMA could exceed the untransformed scheme in all study areas. Some transformed schemes showed unstable performance since they outperformed the untransformed scheme in one area but weakened the SMA result in another region.

  17. High-power direct diode laser output by spectral beam combining

    Science.gov (United States)

    Tan, Hao; Meng, Huicheng; Ruan, Xu; Du, Weichuan; Wang, Zhao

    2018-03-01

    We demonstrate a spectral beam combining scheme based on multiple mini-bar stacks, which have more diode laser combining elements, to increase the combined diode laser power and realize equal beam quality in both the fast and slow axes. A spectral beam combining diode laser output of 1130 W is achieved with an operating current of 75 A. When a 9.6 X de-magnifying telescope is introduced between the output mirror and the diffraction grating, to restrain cross-talk among diode laser emitters, a 710 W spectral beam combining diode laser output is achieved at the operating current of 70 A, and the beam quality on the fast and slow axes of the combined beam is about 7.5 mm mrad and 7.3 mm mrad respectively. The power reduction is caused by the existence of a couple resonator between the rear facet of the diode laser and the fast axis collimation lens, and it should be eliminated by using diode laser chips with higher front facet transmission efficiency and a fast axis collimation lens with lower residual reflectivity.

  18. Narrow spectral linewidth in InAs/InP quantum dot distributed feedback lasers

    Science.gov (United States)

    Duan, J.; Huang, H.; Lu, Z. G.; Poole, P. J.; Wang, C.; Grillot, F.

    2018-03-01

    This paper reports on the spectral linewidth of InAs/InP quantum dot distributed feedback lasers. Owing to a low inversion factor and a low linewidth enhancement factor, a narrow spectral linewidth of 160 kHz (80 kHz intrinsic linewidth) with a low sensitivity to temperature is demonstrated. When using anti-reflection coatings on both facets, narrow linewidth operation is extended to high powers, believed to be due to a reduction in the longitudinal spatial hole burning. These results confirm the high potential of quantum dot lasers for increasing transmission capacity in future coherent communication systems.

  19. Nanoengineering of photonic crystal fibers for supercontinuum spectral shaping

    DEFF Research Database (Denmark)

    Frosz, Michael Henoch; Sørensen, Thorkild; Bang, Ole

    2006-01-01

    ) on the location of the Stokes and anti-Stokes bands and gain bandwidth. An analysis shows that the Raman effect is responsible for reducing the four-wave mixing gain and a slight reduction in the corresponding frequency shift from the pump, when the frequency shift is much larger than the Raman shift. Using......Supercontinuum generation using picosecond pulses pumped into cobweb photonic crystal fibers is investigated. Dispersion profiles are calculated for several fiber designs and used to analytically investigate the influence of the fiber structural parameters (core size and wall thickness...... numerical simulations we find that four-wave mixing is the dominant physical mechanism for the pumping scheme considered, and that there is a trade-off between the spectral width and the spectral flatness of the supercontinuum. The balance of this trade-off is determined by nanometer-scale design...

  20. Spectral properties of plant leaves pertaining to urban landscape design of broad-spectrum solar ultraviolet radiation reduction

    Science.gov (United States)

    Yoshimura, Haruka; Zhu, Hui; Wu, Yunying; Ma, Ruijun

    2010-03-01

    Human exposure to harmful ultraviolet (UV) radiation has important public health implications. Actual human exposure to solar UV radiation depends on ambient UV irradiance, and the latter is influenced by ground reflection. In urban areas with higher reflectivity, UV exposure occurs routinely. To discover the solar UV radiation regulation mechanism of vegetation, the spectral reflectance and transmittance of plant leaves were measured with a spectrophotometer. Typically, higher plants have low leaf reflectance (around 5%) and essentially zero transmittance throughout the UV region regardless of plant species and seasonal change. Accordingly, incident UV radiation decreases to 5% by being reflected and is reduced to zero by passing through a leaf. Therefore, stratified structures of vegetation are working as another terminator of UV rays, protecting whole terrestrial ecosystems, while vegetation at waterfronts contributes to protect aquatic ecosystems. It is possible to protect the human population from harmful UV radiation by urban landscape design of tree shade and the botanical environment. Even thin but uniformly distributed canopy is effective in attenuating UV radiation. To intercept diffuse radiation, UV screening by vertical structures such as hedges should be considered. Reflectivity of vegetation is around 2%, as foliage surfaces reduce incident UV radiation via reflection, while also eliminating it by transmittance. Accordingly, vegetation reduces incident UV radiation to around 2% by reflection. Vegetation influence on ambient UV radiation is broad-spectrum throughout the UV region. Only trees provide cool UV protective shade. Urban landscapes aimed at abating urban heat islands integrated with a reduction of human UV over-exposure would contribute to mitigation of climate change.

  1. Modeling Fire Severity in Black Spruce Stands in the Alaskan Boreal Forest Using Spectral and Non-Spectral Geospatial Data

    Science.gov (United States)

    Barrett, K.; Kasischke, E. S.; McGuire, A. D.; Turetsky, M. R.; Kane, E. S.

    2010-01-01

    Biomass burning in the Alaskan interior is already a major disturbance and source of carbon emissions, and is likely to increase in response to the warming and drying predicted for the future climate. In addition to quantifying changes to the spatial and temporal patterns of burned areas, observing variations in severity is the key to studying the impact of changes to the fire regime on carbon cycling, energy budgets, and post-fire succession. Remote sensing indices of fire severity have not consistently been well-correlated with in situ observations of important severity characteristics in Alaskan black spruce stands, including depth of burning of the surface organic layer. The incorporation of ancillary data such as in situ observations and GIS layers with spectral data from Landsat TM/ETM+ greatly improved efforts to map the reduction of the organic layer in burned black spruce stands. Using a regression tree approach, the R2 of the organic layer depth reduction models was 0.60 and 0.55 (pb0.01) for relative and absolute depth reduction, respectively. All of the independent variables used by the regression tree to estimate burn depth can be obtained independently of field observations. Implementation of a gradient boosting algorithm improved the R2 to 0.80 and 0.79 (pb0.01) for absolute and relative organic layer depth reduction, respectively. Independent variables used in the regression tree model of burn depth included topographic position, remote sensing indices related to soil and vegetation characteristics, timing of the fire event, and meteorological data. Post-fire organic layer depth characteristics are determined for a large (N200,000 ha) fire to identify areas that are potentially vulnerable to a shift in post-fire succession. This application showed that 12% of this fire event experienced fire severe enough to support a change in post-fire succession. We conclude that non-parametric models and ancillary data are useful in the modeling of the surface

  2. Multi-Group Reductions of LTE Air Plasma Radiative Transfer in Cylindrical Geometries

    Science.gov (United States)

    Scoggins, James; Magin, Thierry Edouard Bertran; Wray, Alan; Mansour, Nagi N.

    2013-01-01

    Air plasma radiation in Local Thermodynamic Equilibrium (LTE) within cylindrical geometries is studied with an application towards modeling the radiative transfer inside arc-constrictors, a central component of constricted-arc arc jets. A detailed database of spectral absorption coefficients for LTE air is formulated using the NEQAIR code developed at NASA Ames Research Center. The database stores calculated absorption coefficients for 1,051,755 wavelengths between 0.04 µm and 200 µm over a wide temperature (500K to 15 000K) and pressure (0.1 atm to 10.0 atm) range. The multi-group method for spectral reduction is studied by generating a range of reductions including pure binning and banding reductions from the detailed absorption coefficient database. The accuracy of each reduction is compared to line-by-line calculations for cylindrical temperature profiles resembling typical profiles found in arc-constrictors. It is found that a reduction of only 1000 groups is sufficient to accurately model the LTE air radiation over a large temperature and pressure range. In addition to the reduction comparison, the cylindrical-slab formulation is compared with the finite-volume method for the numerical integration of the radiative flux inside cylinders with varying length. It is determined that cylindrical-slabs can be used to accurately model most arc-constrictors due to their high length to radius ratios.

  3. Coherent spectral amplitude coded label detection for DQPSK payload signals in packet-switched metropolitan area networks

    DEFF Research Database (Denmark)

    Osadchiy, Alexey Vladimirovich; Guerrero Gonzalez, Neil; Jensen, Jesper Bevensee

    2011-01-01

    We report on an experimental demonstration of a frequency swept local oscillator-based spectral amplitude coding (SAC) label detection for DQPSK signals after 40km of fiber transmission. Label detection was performed for a 10.7Gbaud DQPSK signal labeled with a SAC label composed of four......-frequency tones with 500MHz spectral separation. Successful label detection and recognition is achieved with the aid of digital signal processing that allows for substantial reduction of the complexity of the detection optical front-end....

  4. Spectral image reconstruction using an edge preserving spatio-spectral Wiener estimation.

    Science.gov (United States)

    Urban, Philipp; Rosen, Mitchell R; Berns, Roy S

    2009-08-01

    Reconstruction of spectral images from camera responses is investigated using an edge preserving spatio-spectral Wiener estimation. A Wiener denoising filter and a spectral reconstruction Wiener filter are combined into a single spatio-spectral filter using local propagation of the noise covariance matrix. To preserve edges the local mean and covariance matrix of camera responses is estimated by bilateral weighting of neighboring pixels. We derive the edge-preserving spatio-spectral Wiener estimation by means of Bayesian inference and show that it fades into the standard Wiener reflectance estimation shifted by a constant reflectance in case of vanishing noise. Simulation experiments conducted on a six-channel camera system and on multispectral test images show the performance of the filter, especially for edge regions. A test implementation of the method is provided as a MATLAB script at the first author's website.

  5. Spectral Quasi-Equilibrium Manifold for Chemical Kinetics.

    Science.gov (United States)

    Kooshkbaghi, Mahdi; Frouzakis, Christos E; Boulouchos, Konstantinos; Karlin, Iliya V

    2016-05-26

    The Spectral Quasi-Equilibrium Manifold (SQEM) method is a model reduction technique for chemical kinetics based on entropy maximization under constraints built by the slowest eigenvectors at equilibrium. The method is revisited here and discussed and validated through the Michaelis-Menten kinetic scheme, and the quality of the reduction is related to the temporal evolution and the gap between eigenvalues. SQEM is then applied to detailed reaction mechanisms for the homogeneous combustion of hydrogen, syngas, and methane mixtures with air in adiabatic constant pressure reactors. The system states computed using SQEM are compared with those obtained by direct integration of the detailed mechanism, and good agreement between the reduced and the detailed descriptions is demonstrated. The SQEM reduced model of hydrogen/air combustion is also compared with another similar technique, the Rate-Controlled Constrained-Equilibrium (RCCE). For the same number of representative variables, SQEM is found to provide a more accurate description.

  6. Gamma, x-ray reduction system. Volume I: gamma

    International Nuclear Information System (INIS)

    Zimmer, W.H.

    1976-01-01

    The starting premises for this data reduction system were (a) the individual researcher needs all the accuracy that can be achieved but he has neither the time nor the inclination to learn how to achieve it, and (b) if the data reduction system is to be centralized the people operating it will want to minimize conversation with the computer. This is a working system. All spectral data are stored on Data General 4234 discs after background normalization and strip. Storage is initiated from magnetic tapes loaded by detached pulse height analyzers or directly from Scorpio pulse height analyzers. The only restrictions placed on the individual researchers are that the pulse height analyzer energy scale be set up consistently, that a recovery standard be run at least once every day of use, and the total acquisition system be calibrated to its range of use. In many instances, and if desirable, the latter is provided as a service. At the time of writing this gamma data reduction system is actively being used to calculate net peak areas, activities with or without time correction, activations analysis results, counting precisions, and dynamic limits of detection for the spectral data output of 17 detached pulse height analyzers. To all modes of data reduction are applied background subtraction, random summing correction, detector recovery factor correction, peak interfernce correction (second-order product interference for activation analysis), geometry function correction, acquisition time decay corrections, external and internal sorber correction. All of this is accomplished and a customer report typed in a readable format after a halfline of noninteractive instruction

  7. Chest CT using spectral filtration: radiation dose, image quality, and spectrum of clinical utility

    Energy Technology Data Exchange (ETDEWEB)

    Braun, Franziska M.; Johnson, Thorsten R.C.; Sommer, Wieland H.; Thierfelder, Kolja M.; Meinel, Felix G. [University Hospital Munich, Institute for Clinical Radiology, Munich (Germany)

    2015-06-01

    To determine the radiation dose, image quality, and clinical utility of non-enhanced chest CT with spectral filtration. We retrospectively analysed 25 non-contrast chest CT examinations acquired with spectral filtration (tin-filtered Sn100 kVp spectrum) compared to 25 examinations acquired without spectral filtration (120 kV). Radiation metrics were compared. Image noise was measured. Contrast-to-noise-ratio (CNR) and figure-of-merit (FOM) were calculated. Diagnostic confidence for the assessment of various thoracic pathologies was rated by two independent readers. Effective chest diameters were comparable between groups (P = 0.613). In spectral filtration CT, median CTDI{sub vol}, DLP, and size-specific dose estimate (SSDE) were reduced (0.46 vs. 4.3 mGy, 16 vs. 141 mGy*cm, and 0.65 vs. 5.9 mGy, all P < 0.001). Spectral filtration CT had higher image noise (21.3 vs. 13.2 HU, P < 0.001) and lower CNR (47.2 vs. 75.3, P < 0.001), but was more dose-efficient (FOM 10,659 vs. 2,231/mSv, P < 0.001). Diagnostic confidence for parenchymal lung disease and osseous pathologies was lower with spectral filtration CT, but no significant difference was found for pleural pathologies, pulmonary nodules, or pneumonia. Non-contrast chest CT using spectral filtration appears to be sufficient for the assessment of a considerable spectrum of thoracic pathologies, while providing superior dose efficiency, allowing for substantial radiation dose reduction. (orig.)

  8. Spectrally selective glazings

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-08-01

    Spectrally selective glazing is window glass that permits some portions of the solar spectrum to enter a building while blocking others. This high-performance glazing admits as much daylight as possible while preventing transmission of as much solar heat as possible. By controlling solar heat gains in summer, preventing loss of interior heat in winter, and allowing occupants to reduce electric lighting use by making maximum use of daylight, spectrally selective glazing significantly reduces building energy consumption and peak demand. Because new spectrally selective glazings can have a virtually clear appearance, they admit more daylight and permit much brighter, more open views to the outside while still providing the solar control of the dark, reflective energy-efficient glass of the past. This Federal Technology Alert provides detailed information and procedures for Federal energy managers to consider spectrally selective glazings. The principle of spectrally selective glazings is explained. Benefits related to energy efficiency and other architectural criteria are delineated. Guidelines are provided for appropriate application of spectrally selective glazing, and step-by-step instructions are given for estimating energy savings. Case studies are also presented to illustrate actual costs and energy savings. Current manufacturers, technology users, and references for further reading are included for users who have questions not fully addressed here.

  9. Adaptive Spectral Doppler Estimation

    DEFF Research Database (Denmark)

    Gran, Fredrik; Jakobsson, Andreas; Jensen, Jørgen Arendt

    2009-01-01

    . The methods can also provide better quality of the estimated power spectral density (PSD) of the blood signal. Adaptive spectral estimation techniques are known to pro- vide good spectral resolution and contrast even when the ob- servation window is very short. The 2 adaptive techniques are tested......In this paper, 2 adaptive spectral estimation techniques are analyzed for spectral Doppler ultrasound. The purpose is to minimize the observation window needed to estimate the spectrogram to provide a better temporal resolution and gain more flexibility when designing the data acquisition sequence...... and compared with the averaged periodogram (Welch’s method). The blood power spectral capon (BPC) method is based on a standard minimum variance technique adapted to account for both averaging over slow-time and depth. The blood amplitude and phase estimation technique (BAPES) is based on finding a set...

  10. Modal spectral analysis of piping: Determination of the significant frequency range

    International Nuclear Information System (INIS)

    Geraets, L.H.

    1981-01-01

    This paper investigates the influence of the number of modes on the response of a piping system in a dynamic modal spectral analysis. It shows how the analysis can be limited to a specific frequency range of the pipe (independent of the frequency range of the response spectrum), allowing cost reduction without loss in accuracy. The 'missing mass' is taken into account through an original technique. (orig./HP)

  11. An Extended Spectral-Spatial Classification Approach for Hyperspectral Data

    Science.gov (United States)

    Akbari, D.

    2017-11-01

    In this paper an extended classification approach for hyperspectral imagery based on both spectral and spatial information is proposed. The spatial information is obtained by an enhanced marker-based minimum spanning forest (MSF) algorithm. Three different methods of dimension reduction are first used to obtain the subspace of hyperspectral data: (1) unsupervised feature extraction methods including principal component analysis (PCA), independent component analysis (ICA), and minimum noise fraction (MNF); (2) supervised feature extraction including decision boundary feature extraction (DBFE), discriminate analysis feature extraction (DAFE), and nonparametric weighted feature extraction (NWFE); (3) genetic algorithm (GA). The spectral features obtained are then fed into the enhanced marker-based MSF classification algorithm. In the enhanced MSF algorithm, the markers are extracted from the classification maps obtained by both SVM and watershed segmentation algorithm. To evaluate the proposed approach, the Pavia University hyperspectral data is tested. Experimental results show that the proposed approach using GA achieves an approximately 8 % overall accuracy higher than the original MSF-based algorithm.

  12. Spectral/hp element methods: Recent developments, applications, and perspectives

    DEFF Research Database (Denmark)

    Xu, Hui; Cantwell, Chris; Monteserin, Carlos

    2018-01-01

    regularity assumptions an exponential reduction in approximation error between numerical and exact solutions can be achieved. This method has now been applied in many simulation studies of both fundamental and practical engineering flows. This paper briefly describes the formulation of the spectral...... is based upon orthogonal polynomials, such as Legendre or Chebychev polynomials, modified to accommodate a C 0 - continuous expansion. Computationally and theoretically, by increasing the polynomial order p, high-precision solutions and fast convergence can be obtained and, in particular, under certain...

  13. Modeling of detective quantum efficiency considering scatter-reduction devices

    Energy Technology Data Exchange (ETDEWEB)

    Park, Ji Woong; Kim, Dong Woon; Kim, Ho Kyung [Pusan National University, Busan (Korea, Republic of)

    2016-05-15

    The reduction of signal-to-noise ratio (SNR) cannot be restored and thus has become a severe issue in digital mammography.1 Therefore, antiscatter grids are typically used in mammography. Scatter-cleanup performance of various scatter-reduction devices, such as air gaps,2 linear (1D) or cellular (2D) grids,3, 4 and slot-scanning devices,5 has been extensively investigated by many research groups. In the present time, a digital mammography system with the slotscanning geometry is also commercially available.6 In this study, we theoretically investigate the effect of scattered photons on the detective quantum efficiency (DQE) performance of digital mammography detectors by using the cascaded-systems analysis (CSA) approach. We show a simple DQE formalism describing digital mammography detector systems equipped with scatter reduction devices by regarding the scattered photons as additive noise sources. The LFD increased with increasing PMMA thickness, and the amounts of LFD indicated the corresponding SF. The estimated SFs were 0.13, 0.21, and 0.29 for PMMA thicknesses of 10, 20, and 30 mm, respectively. While the solid line describing the measured MTF for PMMA with 0 mm was the result of least-squares of regression fit using Eq. (14), the other lines were simply resulted from the multiplication of the fit result (for PMMA with 0 mm) with the (1-SF) estimated from the LFDs in the measured MTFs. Spectral noise-power densities over the entire frequency range were not much changed with increasing scatter. On the other hand, the calculation results showed that the spectral noise-power densities increased with increasing scatter. This discrepancy may be explained by that the model developed in this study does not account for the changes in x-ray interaction parameters for varying spectral shapes due to beam hardening with increasing PMMA thicknesses.

  14. Hyperspectral imaging of polymer banknotes for building and analysis of spectral library

    Science.gov (United States)

    Lim, Hoong-Ta; Murukeshan, Vadakke Matham

    2017-11-01

    The use of counterfeit banknotes increases crime rates and cripples the economy. New countermeasures are required to stop counterfeiters who use advancing technologies with criminal intent. Many countries started adopting polymer banknotes to replace paper notes, as polymer notes are more durable and have better quality. The research on authenticating such banknotes is of much interest to the forensic investigators. Hyperspectral imaging can be employed to build a spectral library of polymer notes, which can then be used for classification to authenticate these notes. This is however not widely reported and has become a research interest in forensic identification. This paper focuses on the use of hyperspectral imaging on polymer notes to build spectral libraries, using a pushbroom hyperspectral imager which has been previously reported. As an initial study, a spectral library will be built from three arbitrarily chosen regions of interest of five circulated genuine polymer notes. Principal component analysis is used for dimension reduction and to convert the information in the spectral library to principal components. A 99% confidence ellipse is formed around the cluster of principal component scores of each class and then used as classification criteria. The potential of the adopted methodology is demonstrated by the classification of the imaged regions as training samples.

  15. Spectral multitude and spectral dynamics reflect changing conjugation length in single molecules of oligophenylenevinylenes

    KAUST Repository

    Kobayashi, Hiroyuki; Tsuchiya, Kousuke; Ogino, Kenji; Vacha, Martin

    2012-01-01

    Single-molecule study of phenylenevinylene oligomers revealed distinct spectral forms due to different conjugation lengths which are determined by torsional defects. Large spectral jumps between different spectral forms were ascribed to torsional flips of a single phenylene ring. These spectral changes reflect the dynamic nature of electron delocalization in oligophenylenevinylenes and enable estimation of the phenylene torsional barriers. © 2012 The Owner Societies.

  16. Spectral Target Detection using Schroedinger Eigenmaps

    Science.gov (United States)

    Dorado-Munoz, Leidy P.

    Applications of optical remote sensing processes include environmental monitoring, military monitoring, meteorology, mapping, surveillance, etc. Many of these tasks include the detection of specific objects or materials, usually few or small, which are surrounded by other materials that clutter the scene and hide the relevant information. This target detection process has been boosted lately by the use of hyperspectral imagery (HSI) since its high spectral dimension provides more detailed spectral information that is desirable in data exploitation. Typical spectral target detectors rely on statistical or geometric models to characterize the spectral variability of the data. However, in many cases these parametric models do not fit well HSI data that impacts the detection performance. On the other hand, non-linear transformation methods, mainly based on manifold learning algorithms, have shown a potential use in HSI transformation, dimensionality reduction and classification. In target detection, non-linear transformation algorithms are used as preprocessing techniques that transform the data to a more suitable lower dimensional space, where the statistical or geometric detectors are applied. One of these non-linear manifold methods is the Schroedinger Eigenmaps (SE) algorithm that has been introduced as a technique for semi-supervised classification. The core tool of the SE algorithm is the Schroedinger operator that includes a potential term that encodes prior information about the materials present in a scene, and enables the embedding to be steered in some convenient directions in order to cluster similar pixels together. A completely novel target detection methodology based on SE algorithm is proposed for the first time in this thesis. The proposed methodology does not just include the transformation of the data to a lower dimensional space but also includes the definition of a detector that capitalizes on the theory behind SE. The fact that target pixels and

  17. [Review of digital ground object spectral library].

    Science.gov (United States)

    Zhou, Xiao-Hu; Zhou, Ding-Wu

    2009-06-01

    A higher spectral resolution is the main direction of developing remote sensing technology, and it is quite important to set up the digital ground object reflectance spectral database library, one of fundamental research fields in remote sensing application. Remote sensing application has been increasingly relying on ground object spectral characteristics, and quantitative analysis has been developed to a new stage. The present article summarized and systematically introduced the research status quo and development trend of digital ground object reflectance spectral libraries at home and in the world in recent years. Introducing the spectral libraries has been established, including desertification spectral database library, plants spectral database library, geological spectral database library, soil spectral database library, minerals spectral database library, cloud spectral database library, snow spectral database library, the atmosphere spectral database library, rocks spectral database library, water spectral database library, meteorites spectral database library, moon rock spectral database library, and man-made materials spectral database library, mixture spectral database library, volatile compounds spectral database library, and liquids spectral database library. In the process of establishing spectral database libraries, there have been some problems, such as the lack of uniform national spectral database standard and uniform standards for the ground object features as well as the comparability between different databases. In addition, data sharing mechanism can not be carried out, etc. This article also put forward some suggestions on those problems.

  18. Study on the Noise Reduction of Vehicle Exhaust NOX Spectra Based on Adaptive EEMD Algorithm

    Directory of Open Access Journals (Sweden)

    Kai Zhang

    2017-01-01

    Full Text Available It becomes a key technology to measure the concentration of the vehicle exhaust components with the transmission spectra. But in the conventional methods for noise reduction and baseline correction, such as wavelet transform, derivative, interpolation, polynomial fitting, and so forth, the basic functions of these algorithms, the number of decomposition layers, and the way to reconstruct the signal have to be adjusted according to the characteristics of different components in the transmission spectra. The parameter settings of the algorithms above are not transcendental, so with them, it is difficult to achieve the best noise reduction effect for the vehicle exhaust spectra which are sharp and drastic in the waveform. In this paper, an adaptive ensemble empirical mode decomposition (EEMD denoising model based on a special normalized index optimization is proposed and used in the spectral noise reduction of vehicle exhaust NOX. It is shown with the experimental results that the method can effectively improve the accuracy of the spectral noise reduction and simplify the denoising process and its operation difficulty.

  19. Measurement and analysis of neutron flux distribution of STACY heterogeneous core by position sensitive proportional counter. Contract research

    CERN Document Server

    Murazaki, M; Uno, Y

    2003-01-01

    We have measured neutron flux distribution around the core tank of STACY heterogeneous core by position sensitive proportional counter (PSPC) to develop the method to measure reactivity for subcritical systems. The neutron flux distribution data in the position accuracy of +-13 mm have been obtained in the range of uranium concentration of 50g/L to 210g/L both in critical and in subcritical state. The prompt neutron decay constant, alpha, was evaluated from the measurement data of pulsed neutron source experiments. We also calculated distribution of neutron flux and sup 3 He reaction rates at the location of PSPC by using continuous energy Monte Carlo code MCNP. The measurement data was compared with the calculation results. As results of comparison, calculated values agreed generally with measurement data of PSPC with Cd cover in the region above half of solution height, but the difference between calculated value and measurement data was large in the region below half of solution height. On the other hand, ...

  20. Application of advanced data reduction methods to gas turbine dynamic analysis

    International Nuclear Information System (INIS)

    Juhl, P.B.

    1978-01-01

    This paper discusses the application of advanced data reduction methods to the evaluation of dynamic data from gas turbines and turbine components. The use of the Fast Fourier Transform and of real-time spectrum analyzers is discussed. The use of power spectral density and probability density functions for analyzing random data is discussed. Examples of the application of these modern techniques to gas turbine testing are presented. The use of the computer to automate the data reduction procedures is discussed. (orig.) [de

  1. (LMRG): Microscope Resolution, Objective Quality, Spectral Accuracy and Spectral Un-mixing

    Science.gov (United States)

    Bayles, Carol J.; Cole, Richard W.; Eason, Brady; Girard, Anne-Marie; Jinadasa, Tushare; Martin, Karen; McNamara, George; Opansky, Cynthia; Schulz, Katherine; Thibault, Marc; Brown, Claire M.

    2012-01-01

    The second study by the LMRG focuses on measuring confocal laser scanning microscope (CLSM) resolution, objective lens quality, spectral imaging accuracy and spectral un-mixing. Affordable test samples for each aspect of the study were designed, prepared and sent to 116 labs from 23 countries across the globe. Detailed protocols were designed for the three tests and customized for most of the major confocal instruments being used by the study participants. One protocol developed for measuring resolution and objective quality was recently published in Nature Protocols (Cole, R. W., T. Jinadasa, et al. (2011). Nature Protocols 6(12): 1929–1941). The first study involved 3D imaging of sub-resolution fluorescent microspheres to determine the microscope point spread function. Results of the resolution studies as well as point spread function quality (i.e. objective lens quality) from 140 different objective lenses will be presented. The second study of spectral accuracy looked at the reflection of the laser excitation lines into the spectral detection in order to determine the accuracy of these systems to report back the accurate laser emission wavelengths. Results will be presented from 42 different spectral confocal systems. Finally, samples with double orange beads (orange core and orange coating) were imaged spectrally and the imaging software was used to un-mix fluorescence signals from the two orange dyes. Results from 26 different confocal systems will be summarized. Time will be left to discuss possibilities for the next LMRG study.

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

    Science.gov (United States)

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

    2018-01-01

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

  3. Spectral and spectral-frequency methods of investigating atmosphereless bodies of the Solar system

    International Nuclear Information System (INIS)

    Busarev, Vladimir V; Prokof'eva-Mikhailovskaya, Valentina V; Bochkov, Valerii V

    2007-01-01

    A method of reflectance spectrophotometry of atmosphereless bodies of the Solar system, its specificity, and the means of eliminating basic spectral noise are considered. As a development, joining the method of reflectance spectrophotometry with the frequency analysis of observational data series is proposed. The combined spectral-frequency method allows identification of formations with distinctive spectral features, and estimations of their sizes and distribution on the surface of atmospherelss celestial bodies. As applied to investigations of asteroids 21 Lutetia and 4 Vesta, the spectral frequency method has given us the possibility of obtaining fundamentally new information about minor planets. (instruments and methods of investigation)

  4. Estimation of spectral kurtosis

    Science.gov (United States)

    Sutawanir

    2017-03-01

    Rolling bearings are the most important elements in rotating machinery. Bearing frequently fall out of service for various reasons: heavy loads, unsuitable lubrications, ineffective sealing. Bearing faults may cause a decrease in performance. Analysis of bearing vibration signals has attracted attention in the field of monitoring and fault diagnosis. Bearing vibration signals give rich information for early detection of bearing failures. Spectral kurtosis, SK, is a parameter in frequency domain indicating how the impulsiveness of a signal varies with frequency. Faults in rolling bearings give rise to a series of short impulse responses as the rolling elements strike faults, SK potentially useful for determining frequency bands dominated by bearing fault signals. SK can provide a measure of the distance of the analyzed bearings from a healthy one. SK provides additional information given by the power spectral density (psd). This paper aims to explore the estimation of spectral kurtosis using short time Fourier transform known as spectrogram. The estimation of SK is similar to the estimation of psd. The estimation falls in model-free estimation and plug-in estimator. Some numerical studies using simulations are discussed to support the methodology. Spectral kurtosis of some stationary signals are analytically obtained and used in simulation study. Kurtosis of time domain has been a popular tool for detecting non-normality. Spectral kurtosis is an extension of kurtosis in frequency domain. The relationship between time domain and frequency domain analysis is establish through power spectrum-autocovariance Fourier transform. Fourier transform is the main tool for estimation in frequency domain. The power spectral density is estimated through periodogram. In this paper, the short time Fourier transform of the spectral kurtosis is reviewed, a bearing fault (inner ring and outer ring) is simulated. The bearing response, power spectrum, and spectral kurtosis are plotted to

  5. Spectral changes in conifers subjected to air pollution and water stress: Experimental studies

    Science.gov (United States)

    Westman, Walter E.; Price, Curtis V.

    1988-01-01

    The roles of leaf anatomy, moisture and pigment content, and number of leaf layers on spectral reflectance in healthy, pollution-stressed, and water-stressed conifer needles were examined experimentally. Jeffrey pine (Pinus jeffreyi) and giant sequoia (Sequoiadendron gigantea) were exposed to ozone and acid mist treatments in fumigation chambers; red pine (Pinus resinosa) needles were artificially dried. Infrared reflectance from stacked needles rose with free water loss. In an air-drying experiment, cell volume reductions induced by loss of turgor caused near-infrared reflectance (TM band 4) to drop after most free water was lost. Under acid mist fumigation, stunting of tissue development similarly reduced band 4 reflectance. Both artificial drying and pollutant fumigation caused a blue shift of the red edge of spectral reflectance curves in conifers, attributable to chlorophyll denaturation. Thematic mapper band ratio 4/3 fell and 5/4 rose with increasing pollution stress on artificial drying. Loss of water by air-drying, freeze-drying, or oven-drying enhanced spectral features, due in part to greater scattering and reduced water absorption. Grinding of the leaf tissue further enhanced the spectral features by increasing reflecting surfaces and path length. In a leaf-stacking experiment, an asymptote in visible and infrared reflectance was reached at 7-8 needle layers of red pine.

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

    Science.gov (United States)

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

    2016-11-01

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

  7. Spectral stratigraphy

    Science.gov (United States)

    Lang, Harold R.

    1991-01-01

    A new approach to stratigraphic analysis is described which uses photogeologic and spectral interpretation of multispectral remote sensing data combined with topographic information to determine the attitude, thickness, and lithology of strata exposed at the surface. The new stratigraphic procedure is illustrated by examples in the literature. The published results demonstrate the potential of spectral stratigraphy for mapping strata, determining dip and strike, measuring and correlating stratigraphic sequences, defining lithofacies, mapping biofacies, and interpreting geological structures.

  8. Spectral unmixing: estimating partial abundances

    CSIR Research Space (South Africa)

    Debba, Pravesh

    2009-01-01

    Full Text Available techniques is complicated when considering very similar spectral signatures. Iron-bearing oxide/hydroxide/sulfate minerals have similar spectral signatures. The study focuses on how could estimates of abundances of spectrally similar iron-bearing oxide...

  9. Improved classification accuracy of powdery mildew infection levels of wine grapes by spatial-spectral analysis of hyperspectral images.

    Science.gov (United States)

    Knauer, Uwe; Matros, Andrea; Petrovic, Tijana; Zanker, Timothy; Scott, Eileen S; Seiffert, Udo

    2017-01-01

    Hyperspectral imaging is an emerging means of assessing plant vitality, stress parameters, nutrition status, and diseases. Extraction of target values from the high-dimensional datasets either relies on pixel-wise processing of the full spectral information, appropriate selection of individual bands, or calculation of spectral indices. Limitations of such approaches are reduced classification accuracy, reduced robustness due to spatial variation of the spectral information across the surface of the objects measured as well as a loss of information intrinsic to band selection and use of spectral indices. In this paper we present an improved spatial-spectral segmentation approach for the analysis of hyperspectral imaging data and its application for the prediction of powdery mildew infection levels (disease severity) of intact Chardonnay grape bunches shortly before veraison. Instead of calculating texture features (spatial features) for the huge number of spectral bands independently, dimensionality reduction by means of Linear Discriminant Analysis (LDA) was applied first to derive a few descriptive image bands. Subsequent classification was based on modified Random Forest classifiers and selective extraction of texture parameters from the integral image representation of the image bands generated. Dimensionality reduction, integral images, and the selective feature extraction led to improved classification accuracies of up to [Formula: see text] for detached berries used as a reference sample (training dataset). Our approach was validated by predicting infection levels for a sample of 30 intact bunches. Classification accuracy improved with the number of decision trees of the Random Forest classifier. These results corresponded with qPCR results. An accuracy of 0.87 was achieved in classification of healthy, infected, and severely diseased bunches. However, discrimination between visually healthy and infected bunches proved to be challenging for a few samples

  10. Introduction to spectral theory

    CERN Document Server

    Levitan, B M

    1975-01-01

    This monograph is devoted to the spectral theory of the Sturm- Liouville operator and to the spectral theory of the Dirac system. In addition, some results are given for nth order ordinary differential operators. Those parts of this book which concern nth order operators can serve as simply an introduction to this domain, which at the present time has already had time to become very broad. For the convenience of the reader who is not familar with abstract spectral theory, the authors have inserted a chapter (Chapter 13) in which they discuss this theory, concisely and in the main without proofs, and indicate various connections with the spectral theory of differential operators.

  11. A hybrid spatial-spectral denoising method for infrared hyperspectral images using 2DPCA

    Science.gov (United States)

    Huang, Jun; Ma, Yong; Mei, Xiaoguang; Fan, Fan

    2016-11-01

    The traditional noise reduction methods for 3-D infrared hyperspectral images typically operate independently in either the spatial or spectral domain, and such methods overlook the relationship between the two domains. To address this issue, we propose a hybrid spatial-spectral method in this paper to link both domains. First, principal component analysis and bivariate wavelet shrinkage are performed in the 2-D spatial domain. Second, 2-D principal component analysis transformation is conducted in the 1-D spectral domain to separate the basic components from detail ones. The energy distribution of noise is unaffected by orthogonal transformation; therefore, the signal-to-noise ratio of each component is used as a criterion to determine whether a component should be protected from over-denoising or denoised with certain 1-D denoising methods. This study implements the 1-D wavelet shrinking threshold method based on Stein's unbiased risk estimator, and the quantitative results on publicly available datasets demonstrate that our method can improve denoising performance more effectively than other state-of-the-art methods can.

  12. [Analysis of sensitive spectral bands for burning status detection using hyper-spectral images of Tiangong-01].

    Science.gov (United States)

    Qin, Xian-Lin; Zhu, Xi; Yang, Fei; Zhao, Kai-Rui; Pang, Yong; Li, Zeng-Yuan; Li, Xu-Zhi; Zhang, Jiu-Xing

    2013-07-01

    To obtain the sensitive spectral bands for detection of information on 4 kinds of burning status, i. e. flaming, smoldering, smoke, and fire scar, with satellite data, analysis was conducted to identify suitable satellite spectral bands for detection of information on these 4 kinds of burning status by using hyper-spectrum images of Tiangong-01 (TG-01) and employing a method combining statistics and spectral analysis. The results show that: in the hyper-spectral images of TG-01, the spectral bands differ obviously for detection of these 4 kinds of burning status; in all hyper-spectral short-wave infrared channels, the reflectance of flaming is higher than that of all other 3 kinds of burning status, and the reflectance of smoke is the lowest; the reflectance of smoke is higher than that of all other 3 kinds of burning status in the channels corresponding to hyper-spectral visible near-infrared and panchromatic sensors. For spectral band selection, more suitable spectral bands for flaming detection are 1 000.0-1 956.0 and 2 020.0-2 400.0 nm; the suitable spectral bands for identifying smoldering are 930.0-1 000.0 and 1 084.0-2 400.0 nm; the suitable spectral bands for smoke detection is in 400.0-920.0 nm; for fire scar detection, it is suitable to select bands with central wavelengths of 900.0-930.0 and 1 300.0-2 400.0 nm, and then to combine them to construct a detection model.

  13. 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...

  14. Reduction in electromagnetic interference of switching converters using self-excitation-chaos

    DEFF Research Database (Denmark)

    Li, Qingnan; Xiong, Rui; He, Ou

    2008-01-01

    operating in chaos, the simulation results demonstrate that a reduction of spectral peak and consequent spreading of the spectrum can be shown, any desirable amount of reduction and consequent spreading of the spectrum can be obtained simply by varying the control parameter of the circuit and a optimization......We derived a second-order S-switching iterative map describing the dynamics of simple feedback Buck switching regulator operating in continuous mode. Analysis of this map shows that chaos and bifurcations may occur along with the changing of values of some system parameters. By making the converter...

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

    Science.gov (United States)

    Liu, Qiang; Wan, Xiaoxia; Xie, Dehong

    2014-06-01

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

  16. Spectral and energy efficiency analysis of uplink heterogeneous networks with small-cells on edge

    KAUST Repository

    Shakir, Muhammad Zeeshan

    2014-12-01

    This paper presents a tractable mathematical framework to analyze the spectral and energy efficiency of an operator initiated deployment of the small-cells (e.g., femtocells) where the small-cell base stations are deliberately positioned around the edge of the macrocell. The considered deployment facilitates the cell-edge mobile users in terms of their coverage, spectral, and energy efficiency and is referred to as cell-on-edge (COE) configuration. The reduction in energy consumption is achieved by considering fast power control where the mobile users transmit with adaptive power to compensate the path loss, shadowing and fading. In particular, we develop a moment generating function (MGF) based approach to derive analytical bounds on the area spectral efficiency and exact expressions for the energy efficiency of the mobile users in the considered COE configuration over generalized-K fading channels. Besides the COE configuration, the derived bounds are also shown to be useful in evaluating the performance of random small-cell deployments, e.g., uniformly distributed small-cells. Simulation results are presented to demonstrate the improvements in spectral and energy efficiency of the COE configuration with respect to macro-only networks and other unplanned deployment strategies. © 2014 Elsevier B.V. All rights reserved.

  17. Parallel Framework for Dimensionality Reduction of Large-Scale Datasets

    Directory of Open Access Journals (Sweden)

    Sai Kiranmayee Samudrala

    2015-01-01

    Full Text Available Dimensionality reduction refers to a set of mathematical techniques used to reduce complexity of the original high-dimensional data, while preserving its selected properties. Improvements in simulation strategies and experimental data collection methods are resulting in a deluge of heterogeneous and high-dimensional data, which often makes dimensionality reduction the only viable way to gain qualitative and quantitative understanding of the data. However, existing dimensionality reduction software often does not scale to datasets arising in real-life applications, which may consist of thousands of points with millions of dimensions. In this paper, we propose a parallel framework for dimensionality reduction of large-scale data. We identify key components underlying the spectral dimensionality reduction techniques, and propose their efficient parallel implementation. We show that the resulting framework can be used to process datasets consisting of millions of points when executed on a 16,000-core cluster, which is beyond the reach of currently available methods. To further demonstrate applicability of our framework we perform dimensionality reduction of 75,000 images representing morphology evolution during manufacturing of organic solar cells in order to identify how processing parameters affect morphology evolution.

  18. Bit-rate reduction strategies for noise suppression with a remote wireless microphone

    NARCIS (Netherlands)

    Cvijanovic, N.; Sadiq, O.; Srinivasan, S.

    2012-01-01

    In single channel non-stationary noise reduction it is paramount that a good noise reference is available in a timely manner to maintaina high quality speech signal. Using a remote wireless microphone placed close to a noise source, a good estimate of the noise power spectral density (PSD) can be

  19. Bit rate reduction strategies for noise suppression using a remote wireless microphone

    NARCIS (Netherlands)

    Cvijanovic, N.; Sadiq, O.; Srinivasan, S.

    2012-01-01

    In single-channel non-stationary noise reduction it is paramount that a good noise reference is available in a timely manner to maintain a high quality speech signal. Using a remote wireless microphone placed close to a noise source, a good estimate of the noise power spectral density (PSD) can be

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

    Directory of Open Access Journals (Sweden)

    Qu Lijia

    2009-03-01

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

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

    Science.gov (United States)

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

    2009-03-16

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

  2. Spectacle and SpecViz: New Spectral Analysis and Visualization Tools

    Science.gov (United States)

    Earl, Nicholas; Peeples, Molly; JDADF Developers

    2018-01-01

    A new era of spectroscopic exploration of our universe is being ushered in with advances in instrumentation and next-generation space telescopes. The advent of new spectroscopic instruments has highlighted a pressing need for tools scientists can use to analyze and explore these new data. We have developed Spectacle, a software package for analyzing both synthetic spectra from hydrodynamic simulations as well as real COS data with an aim of characterizing the behavior of the circumgalactic medium. It allows easy reduction of spectral data and analytic line generation capabilities. Currently, the package is focused on automatic determination of absorption regions and line identification with custom line list support, simultaneous line fitting using Voigt profiles via least-squares or MCMC methods, and multi-component modeling of blended features. Non-parametric measurements, such as equivalent widths, delta v90, and full-width half-max are available. Spectacle also provides the ability to compose compound models used to generate synthetic spectra allowing the user to define various LSF kernels, uncertainties, and to specify sampling.We also present updates to the visualization tool SpecViz, developed in conjunction with the JWST data analysis tools development team, to aid in the exploration of spectral data. SpecViz is an open source, Python-based spectral 1-D interactive visualization and analysis application built around high-performance interactive plotting. It supports handling general and instrument-specific data and includes advanced tool-sets for filtering and detrending one-dimensional data, along with the ability to isolate absorption regions using slicing and manipulate spectral features via spectral arithmetic. Multi-component modeling is also possible using a flexible model fitting tool-set that supports custom models to be used with various fitting routines. It also features robust user extensions such as custom data loaders and support for user

  3. Understanding A-type supergiants. I. Ultraviolet and visible spectral atlas of A-type supergiants

    CERN Document Server

    Verdugo, E; Gómez de Castro, A I

    1999-01-01

    This paper is the first of a series whose aim is to perform a systematic study of A-type supergiant atmospheres and winds. Here we present a spectral atlas of 41 A-supergiants observed by us in high and medium resolution in the visible and ultraviolet. The atlas consists of profiles of the H alpha , H beta , H gamma , H delta , H epsilon , Ca II (H and K), Na I (D1 and D2), Mg II/sub 4481/, Mg II uv1 and Fe II uv1, uv2, uv3, uv62, uv63, uv161 lines for 41 stars with spectral types ranging from B9 to A9 and luminosity classes Ia, Iab and Ib, and provides the basic data for a thoughtful study of these stars. The overall characteristics of the sample as well as the data reduction procedures are described. We also present some examples of spectral variability. Figures 1-3 are only available in electronic form at http://www.edpsciences.com. (27 refs).

  4. Spectral radius of graphs

    CERN Document Server

    Stevanovic, Dragan

    2015-01-01

    Spectral Radius of Graphs provides a thorough overview of important results on the spectral radius of adjacency matrix of graphs that have appeared in the literature in the preceding ten years, most of them with proofs, and including some previously unpublished results of the author. The primer begins with a brief classical review, in order to provide the reader with a foundation for the subsequent chapters. Topics covered include spectral decomposition, the Perron-Frobenius theorem, the Rayleigh quotient, the Weyl inequalities, and the Interlacing theorem. From this introduction, the

  5. Spectral L2/L1 norm: A new perspective for spectral kurtosis for characterizing non-stationary signals

    Science.gov (United States)

    Wang, Dong

    2018-05-01

    Thanks to the great efforts made by Antoni (2006), spectral kurtosis has been recognized as a milestone for characterizing non-stationary signals, especially bearing fault signals. The main idea of spectral kurtosis is to use the fourth standardized moment, namely kurtosis, as a function of spectral frequency so as to indicate how repetitive transients caused by a bearing defect vary with frequency. Moreover, spectral kurtosis is defined based on an analytic bearing fault signal constructed from either a complex filter or Hilbert transform. On the other hand, another attractive work was reported by Borghesani et al. (2014) to mathematically reveal the relationship between the kurtosis of an analytical bearing fault signal and the square of the squared envelope spectrum of the analytical bearing fault signal for explaining spectral correlation for quantification of bearing fault signals. More interestingly, it was discovered that the sum of peaks at cyclic frequencies in the square of the squared envelope spectrum corresponds to the raw 4th order moment. Inspired by the aforementioned works, in this paper, we mathematically show that: (1) spectral kurtosis can be decomposed into squared envelope and squared L2/L1 norm so that spectral kurtosis can be explained as spectral squared L2/L1 norm; (2) spectral L2/L1 norm is formally defined for characterizing bearing fault signals and its two geometrical explanations are made; (3) spectral L2/L1 norm is proportional to the square root of the sum of peaks at cyclic frequencies in the square of the squared envelope spectrum; (4) some extensions of spectral L2/L1 norm for characterizing bearing fault signals are pointed out.

  6. On reductions of the discrete Kadomtsev-Petviashvili-type equations

    Science.gov (United States)

    Fu, Wei; Nijhoff, Frank W.

    2017-12-01

    The reduction by restricting the spectral parameters k and k\\prime on a generic algebraic curve of degree N is performed for the discrete AKP, BKP and CKP equations, respectively. A variety of two-dimensional discrete integrable systems possessing a more general solution structure arise from the reduction, and in each case a unified formula for the generic positive integer N≥slant 2 is given to express the corresponding reduced integrable lattice equations. The obtained extended two-dimensional lattice models give rise to many important integrable partial difference equations as special degenerations. Some new integrable lattice models such as the discrete Sawada-Kotera, Kaup-Kupershmidt and Hirota-Satsuma equations in extended form are given as examples within the framework.

  7. Spectral methods. Fundamentals in single domains

    International Nuclear Information System (INIS)

    Canuto, C.

    2006-01-01

    Since the publication of ''Spectral Methods in Fluid Dynamics'' 1988, spectral methods have become firmly established as a mainstream tool for scientific and engineering computation. The authors of that book have incorporated into this new edition the many improvements in the algorithms and the theory of spectral methods that have been made since then. This latest book retains the tight integration between the theoretical and practical aspects of spectral methods, and the chapters are enhanced with material on the Galerkin with numerical integration version of spectral methods. The discussion of direct and iterative solution methods is also greatly expanded. (orig.)

  8. Vowel Inherent Spectral Change

    CERN Document Server

    Assmann, Peter

    2013-01-01

    It has been traditional in phonetic research to characterize monophthongs using a set of static formant frequencies, i.e., formant frequencies taken from a single time-point in the vowel or averaged over the time-course of the vowel. However, over the last twenty years a growing body of research has demonstrated that, at least for a number of dialects of North American English, vowels which are traditionally described as monophthongs often have substantial spectral change. Vowel Inherent Spectral Change has been observed in speakers’ productions, and has also been found to have a substantial effect on listeners’ perception. In terms of acoustics, the traditional categorical distinction between monophthongs and diphthongs can be replaced by a gradient description of dynamic spectral patterns. This book includes chapters addressing various aspects of vowel inherent spectral change (VISC), including theoretical and experimental studies of the perceptually relevant aspects of VISC, the relationship between ar...

  9. Spectral imaging spreads into new industrial and on-field applications

    Science.gov (United States)

    Bouyé, Clémentine; Robin, Thierry; d'Humières, Benoît

    2018-02-01

    Numerous recent innovative developments have led to a high reduction of hyperspectral and multispectral cameras cost and size. The achieved products - compact, reliable, low-cot, easy-to-use - meet end-user requirements in major fields: agriculture, food and beverages, pharmaceutics, machine vision, health. The booming of this technology in industrial and on-field applications is getting closer. Indeed, the Spectral Imaging market is at a turning point. A high growth rate of 20% is expected in the next 5 years. The number of cameras sold will increase from 3 600 in 2017 to more than 9 000 in 2022.

  10. Spectrally accurate contour dynamics

    International Nuclear Information System (INIS)

    Van Buskirk, R.D.; Marcus, P.S.

    1994-01-01

    We present an exponentially accurate boundary integral method for calculation the equilibria and dynamics of piece-wise constant distributions of potential vorticity. The method represents contours of potential vorticity as a spectral sum and solves the Biot-Savart equation for the velocity by spectrally evaluating a desingularized contour integral. We use the technique in both an initial-value code and a newton continuation method. Our methods are tested by comparing the numerical solutions with known analytic results, and it is shown that for the same amount of computational work our spectral methods are more accurate than other contour dynamics methods currently in use

  11. Assessing the role of spectral and intensity cues in spectral ripple detection and discrimination in cochlear-implant users.

    Science.gov (United States)

    Anderson, Elizabeth S; Oxenham, Andrew J; Nelson, Peggy B; Nelson, David A

    2012-12-01

    Measures of spectral ripple resolution have become widely used psychophysical tools for assessing spectral resolution in cochlear-implant (CI) listeners. The objective of this study was to compare spectral ripple discrimination and detection in the same group of CI listeners. Ripple detection thresholds were measured over a range of ripple frequencies and were compared to spectral ripple discrimination thresholds previously obtained from the same CI listeners. The data showed that performance on the two measures was correlated, but that individual subjects' thresholds (at a constant spectral modulation depth) for the two tasks were not equivalent. In addition, spectral ripple detection was often found to be possible at higher rates than expected based on the available spectral cues, making it likely that temporal-envelope cues played a role at higher ripple rates. Finally, spectral ripple detection thresholds were compared to previously obtained speech-perception measures. Results confirmed earlier reports of a robust relationship between detection of widely spaced ripples and measures of speech recognition. In contrast, intensity difference limens for broadband noise did not correlate with spectral ripple detection measures, suggesting a dissociation between the ability to detect small changes in intensity across frequency and across time.

  12. Spectral and cross-spectral analysis of uneven time series with the smoothed Lomb-Scargle periodogram and Monte Carlo evaluation of statistical significance

    Science.gov (United States)

    Pardo-Igúzquiza, Eulogio; Rodríguez-Tovar, Francisco J.

    2012-12-01

    Many spectral analysis techniques have been designed assuming sequences taken with a constant sampling interval. However, there are empirical time series in the geosciences (sediment cores, fossil abundance data, isotope analysis, …) that do not follow regular sampling because of missing data, gapped data, random sampling or incomplete sequences, among other reasons. In general, interpolating an uneven series in order to obtain a succession with a constant sampling interval alters the spectral content of the series. In such cases it is preferable to follow an approach that works with the uneven data directly, avoiding the need for an explicit interpolation step. The Lomb-Scargle periodogram is a popular choice in such circumstances, as there are programs available in the public domain for its computation. One new computer program for spectral analysis improves the standard Lomb-Scargle periodogram approach in two ways: (1) It explicitly adjusts the statistical significance to any bias introduced by variance reduction smoothing, and (2) it uses a permutation test to evaluate confidence levels, which is better suited than parametric methods when neighbouring frequencies are highly correlated. Another novel program for cross-spectral analysis offers the advantage of estimating the Lomb-Scargle cross-periodogram of two uneven time series defined on the same interval, and it evaluates the confidence levels of the estimated cross-spectra by a non-parametric computer intensive permutation test. Thus, the cross-spectrum, the squared coherence spectrum, the phase spectrum, and the Monte Carlo statistical significance of the cross-spectrum and the squared-coherence spectrum can be obtained. Both of the programs are written in ANSI Fortran 77, in view of its simplicity and compatibility. The program code is of public domain, provided on the website of the journal (http://www.iamg.org/index.php/publisher/articleview/frmArticleID/112/). Different examples (with simulated and

  13. Scaling analyses of the spectral dimension in 3-dimensional causal dynamical triangulations

    Science.gov (United States)

    Cooperman, Joshua H.

    2018-05-01

    The spectral dimension measures the dimensionality of a space as witnessed by a diffusing random walker. Within the causal dynamical triangulations approach to the quantization of gravity (Ambjørn et al 2000 Phys. Rev. Lett. 85 347, 2001 Nucl. Phys. B 610 347, 1998 Nucl. Phys. B 536 407), the spectral dimension exhibits novel scale-dependent dynamics: reducing towards a value near 2 on sufficiently small scales, matching closely the topological dimension on intermediate scales, and decaying in the presence of positive curvature on sufficiently large scales (Ambjørn et al 2005 Phys. Rev. Lett. 95 171301, Ambjørn et al 2005 Phys. Rev. D 72 064014, Benedetti and Henson 2009 Phys. Rev. D 80 124036, Cooperman 2014 Phys. Rev. D 90 124053, Cooperman et al 2017 Class. Quantum Grav. 34 115008, Coumbe and Jurkiewicz 2015 J. High Energy Phys. JHEP03(2015)151, Kommu 2012 Class. Quantum Grav. 29 105003). I report the first comprehensive scaling analysis of the small-to-intermediate scale spectral dimension for the test case of the causal dynamical triangulations of 3-dimensional Einstein gravity. I find that the spectral dimension scales trivially with the diffusion constant. I find that the spectral dimension is completely finite in the infinite volume limit, and I argue that its maximal value is exactly consistent with the topological dimension of 3 in this limit. I find that the spectral dimension reduces further towards a value near 2 as this case’s bare coupling approaches its phase transition, and I present evidence against the conjecture that the bare coupling simply sets the overall scale of the quantum geometry (Ambjørn et al 2001 Phys. Rev. D 64 044011). On the basis of these findings, I advance a tentative physical explanation for the dynamical reduction of the spectral dimension observed within causal dynamical triangulations: branched polymeric quantum geometry on sufficiently small scales. My analyses should facilitate attempts to employ the spectral

  14. Intersection numbers of spectral curves

    CERN Document Server

    Eynard, B.

    2011-01-01

    We compute the symplectic invariants of an arbitrary spectral curve with only 1 branchpoint in terms of integrals of characteristic classes in the moduli space of curves. Our formula associates to any spectral curve, a characteristic class, which is determined by the laplace transform of the spectral curve. This is a hint to the key role of Laplace transform in mirror symmetry. When the spectral curve is y=\\sqrt{x}, the formula gives Kontsevich--Witten intersection numbers, when the spectral curve is chosen to be the Lambert function \\exp{x}=y\\exp{-y}, the formula gives the ELSV formula for Hurwitz numbers, and when one chooses the mirror of C^3 with framing f, i.e. \\exp{-x}=\\exp{-yf}(1-\\exp{-y}), the formula gives the Marino-Vafa formula, i.e. the generating function of Gromov-Witten invariants of C^3. In some sense this formula generalizes ELSV, Marino-Vafa formula, and Mumford formula.

  15. Atmospheric parameters, spectral indexes and their relation to CPV spectral performance

    Energy Technology Data Exchange (ETDEWEB)

    Núñez, Rubén, E-mail: ruben.nunez@ies-def.upm.es; Antón, Ignacio, E-mail: ruben.nunez@ies-def.upm.es; Askins, Steve, E-mail: ruben.nunez@ies-def.upm.es; Sala, Gabriel, E-mail: ruben.nunez@ies-def.upm.es [Instituto de Energía Solar - Universidad Politécnica de Madrid, Instituto de Energía Solar, ETSI Telecomunicación, Ciudad Universitaria 28040 Madrid (Spain)

    2014-09-26

    Air Mass and atmosphere components (basically aerosol (AOD) and precipitable water (PW)) define the absorption of the sunlight that arrive to Earth. Radiative models such as SMARTS or MODTRAN use these parameters to generate an equivalent spectrum. However, complex and expensive instruments (as AERONET network devices) are needed to obtain AOD and PW. On the other hand, the use of isotype cells is a convenient way to characterize spectrally a place for CPV considering that they provide the photocurrent of the different internal subcells individually. Crossing data from AERONET station and a Tri-band Spectroheliometer, a model that correlates Spectral Mismatch Ratios and atmospheric parameters is proposed. Considering the amount of stations of AERONET network, this model may be used to estimate the spectral influence on energy performance of CPV systems close to all the stations worldwide.

  16. Calibration with near-continuous spectral measurements

    DEFF Research Database (Denmark)

    Nielsen, Henrik Aalborg; Rasmussen, Michael; Madsen, Henrik

    2001-01-01

    In chemometrics traditional calibration in case of spectral measurements express a quantity of interest (e.g. a concentration) as a linear combination of the spectral measurements at a number of wavelengths. Often the spectral measurements are performed at a large number of wavelengths and in thi...... by an example in which the octane number of gasoline is related to near infrared spectral measurements. The performance is found to be much better that for the traditional calibration methods....

  17. Calibrating spectral images using penalized likelihood

    NARCIS (Netherlands)

    Heijden, van der G.W.A.M.; Glasbey, C.

    2003-01-01

    A new method is presented for automatic correction of distortions and for spectral calibration (which band corresponds to which wavelength) of spectral images recorded by means of a spectrograph. The method consists of recording a bar-like pattern with an illumination source with spectral bands

  18. Spectral Learning for Supervised Topic Models.

    Science.gov (United States)

    Ren, Yong; Wang, Yining; Zhu, Jun

    2018-03-01

    Supervised topic models simultaneously model the latent topic structure of large collections of documents and a response variable associated with each document. Existing inference methods are based on variational approximation or Monte Carlo sampling, which often suffers from the local minimum defect. Spectral methods have been applied to learn unsupervised topic models, such as latent Dirichlet allocation (LDA), with provable guarantees. This paper investigates the possibility of applying spectral methods to recover the parameters of supervised LDA (sLDA). We first present a two-stage spectral method, which recovers the parameters of LDA followed by a power update method to recover the regression model parameters. Then, we further present a single-phase spectral algorithm to jointly recover the topic distribution matrix as well as the regression weights. Our spectral algorithms are provably correct and computationally efficient. We prove a sample complexity bound for each algorithm and subsequently derive a sufficient condition for the identifiability of sLDA. Thorough experiments on synthetic and real-world datasets verify the theory and demonstrate the practical effectiveness of the spectral algorithms. In fact, our results on a large-scale review rating dataset demonstrate that our single-phase spectral algorithm alone gets comparable or even better performance than state-of-the-art methods, while previous work on spectral methods has rarely reported such promising performance.

  19. Metallicity and the spectral energy distribution and spectral types of dwarf O-stars

    NARCIS (Netherlands)

    Mokiem, MR; Martin-Hernandez, NL; Lenorzer, A; de Koter, A; Tielens, AGGA

    We present a systematic study of the effect of metallicity on the stellar spectral energy distribution (SED) of 0 main sequence (dwarf) stars, focussing on the hydrogen and helium ionizing continua, and on the optical and near-IR lines used for spectral classification. The spectra are based on

  20. Metallicity and the spectral energy distribution and spectral types of dwarf O-stars

    NARCIS (Netherlands)

    Mokiem, M.R.; Martín-Hernández, N.L.; Lenorzer, A.; de Koter, A.; Tielens, A.G.G.M.

    2004-01-01

    We present a systematic study of the effect of metallicity on the stellar spectral energy distribution (SED) of O main sequence (dwarf) stars, focussing on the hydrogen and helium ionizing continua, and on the optical and near-IR lines used for spectral classification. The spectra are based on

  1. The green hemoproteins of bovine erythrocytes. II. Spectral, ligand-binding, and electrochemical properties.

    Science.gov (United States)

    DeFilippi, L J; Hultquist, D E

    1978-05-10

    The two green hemoproteins isolated from bovine erythrocytes (form I and form II) have been characterized as to spectral, electrochemical, and chemical properties. The absorption spectra of the isolated hemoproteins are typical of high spin ferric states. Reduction of the hemoproteins yields high spin ferrohemoproteins. Complexation of the ferrohemoproteins with CO and the ferrihemoproteins with cyanide yields low spin complexes, demonstrating the presence of an exchangeable weak field ligand in both the ferrous and ferric states of the hemoproteins. The differences in position and intensity of the absorption peaks of the visible spectra allow the two forms to be distinguished from one another. The midpoint potential of forms I and II were found to be +0.075 and +0.019 V, respectively, at pH 6.4 and +0.038 and -0.005 V, respectively, at pH 7.0. This is consistent with the gaining of 1 proton/electron during the reduction. The Nernst plot reveals an unusual 0.5-electron transfer, whereas a quantitative titration demonstrates a 1-electron transfer. Form I binds cyanide more tightly than form II (KD of 84 and 252 micrometer, respectively). The observed spectral, electrochemical, and ligand-binding differences between forms I and II can be explained in terms of a greater electron-withdrawing ability of the side chains of the heme of form I relative to the heme of form II.

  2. Analysis of Beamformer Directed Single-Channel Noise Reduction System for Hearing Aid Applications

    DEFF Research Database (Denmark)

    Jensen, Jesper; Pedersen, Michael Syskind

    2015-01-01

    We study multi-microphone noise reduction systems consisting of a beamformer and a single-channel (SC) noise reduction stage. In particular, we present and analyse a maximum likelihood (ML) method for jointly estimating the target and noise power spectral densities (psd's) entering the SC filter....... We show that the estimators are minimum variance and unbiased, and provide closed-form expressions for their mean-square error (MSE). Furthermore, we show that the MSE of the noise psd estimator is particularly simple: it is independent of target signal characteristics, frequency, and microphone...

  3. Generation of a new spectral format, the lifetime synchronous spectrum (LiSS), using phase-resolved fluorescence spectroscopy

    International Nuclear Information System (INIS)

    Shaver, J.M.; McGown, L.B.

    1994-01-01

    A new fluorescence spectral format is introduced in which fluorescence lifetime is shown as a function of synchronously scanned wavelength to generate a Lifetime Synchronous Spectrum (LiSS). Lifetimes are determined in the frequency domain with the use of Phase-Resolved Fluorescence Spectroscopy (PRFS) to obtain the phase of the fluorescence signal. Theory and construction of the LiSS are presented and experimental results are shown for solutions of single components and simple binary and ternary mixtures. These results show how the lifetime information in the LiSS augments the steady-state intensity information of a standard synchronous spectrum, providing unique information for identification of components and resolution of overlapping spectral peaks. The LiSS technique takes advantage of noise reduction inherent in the extraction of lifetime from PRFS in addition to standard spectral smoothing techniques. The precision of phase determination through PRFS is found to be comparable to that of direct phase measurements at normal fluorescence intensities and superior for low-intensity signals

  4. Spectral filtering for plant production

    Energy Technology Data Exchange (ETDEWEB)

    Young, R.E.; McMahon, M.J.; Rajapakse, N.C.; Becoteau, D.R.

    1994-12-31

    Research to date suggests that spectral filtering can be an effective alternative to chemical growth regulators for altering plant development. If properly implemented, it can be nonchemical and environmentally friendly. The aqueous CuSO{sub 4}, and CuCl{sub 2} solutions in channelled plastic panels have been shown to be effective filters, but they can be highly toxic if the solutions contact plants. Some studies suggest that spectral filtration limited to short EOD intervals can also alter plant development. Future research should be directed toward confirmation of the influence of spectral filters and exposure times on a broader range of plant species and cultivars. Efforts should also be made to identify non-noxious alternatives to aqueous copper solutions and/or to incorporate these chemicals permanently into plastic films and panels that can be used in greenhouse construction. It would also be informative to study the impacts of spectral filters on insect and microbal populations in plant growth facilities. The economic impacts of spectral filtering techniques should be assessed for each delivery methodology.

  5. Evaluating the capabilities of vegetation spectral indices on chlorophyll content estimation at Sentinel-2 spectral resolutions

    Science.gov (United States)

    Sun, Qi; Jiao, Quanjun; Dai, Huayang

    2018-03-01

    Chlorophyll is an important pigment in green plants for photosynthesis and obtaining the energy for growth and development. The rapid, nondestructive and accurate estimation of chlorophyll content is significant for understanding the crops growth, monitoring the disease and insect, and assessing the yield of crops. Sentinel-2 equipped with the Multi-Spectral Instrument (MSI), which will provide images with high spatial, spectral and temporal resolution. It covers the VNIR/SWIR spectral region in 13 bands and incorporates two new spectral bands in the red-edge region and a spatial resolution of 20nm, which can be used to derive vegetation indices using red-edge bands. In this paper, we will focus on assessing the potential of vegetation spectral indices for retrieving chlorophyll content from Sentinel-2 at different angles. Subsequently, we used in-situ spectral data and Sentinel-2 data to test the relationship between VIs and chlorophyll content. The REP, MTCI, CIred-edge, CIgreen, Macc01, TCARI/OSAVI [705,750], NDRE1 and NDRE2 were calculated. NDRE2 index displays a strongly similar result for hyperspectral and simulated Sentinel-2 spectral bands (R2 =0.53, R2 =0.51, for hyperspectral and Sentinel-2, respectively). At different observation angles, NDRE2 has the smallest difference in performance (R2 = 0.51, R2 =0.64, at 0° and 15° , respectively).

  6. Spectral and Power-Efficiency Trade-off in Fixed-Grid Optical Networks

    Directory of Open Access Journals (Sweden)

    Sridhar Iyer

    2017-09-01

    Full Text Available The improvement of spectral efficiency in the MLR networks can be obtained by the reduction of sub-band spacing, or by minimizing the spacing of the sub-bands that operate at varied data rates. However, due to the presence of physical layer impairments, minimization in sub-band spacing leads to adverse effects on the channel(s transmission reach. As a result there occurs an increase in the consumed power due to the requirement of increase in regeneration of the signal. In the current work we propose an improved DWDM grating in view of obtaining higher spectral efficiency. For a system, with and without Forward Error Correction capabilities (i for various SLR solutions, we find and compare power consumption values of the components with respect to the total traffic, and (ii for different MLR and SLR solutions, for a fixed QoT, we evaluate the minimum values of the sub-band and the channel spacing, and also evaluate and compare the power-efficiency with the distance of transmission.

  7. On Longitudinal Spectral Coherence

    DEFF Research Database (Denmark)

    Kristensen, Leif

    1979-01-01

    It is demonstrated that the longitudinal spectral coherence differs significantly from the transversal spectral coherence in its dependence on displacement and frequency. An expression for the longitudinal coherence is derived and it is shown how the scale of turbulence, the displacement between ...... observation sites and the turbulence intensity influence the results. The limitations of the theory are discussed....

  8. Speech recognition from spectral dynamics

    Indian Academy of Sciences (India)

    Carrier nature of speech; modulation spectrum; spectral dynamics ... the relationships between phonetic values of sounds and their short-term spectral envelopes .... the number of free parameters that need to be estimated from training data.

  9. Meson spectral functions at finite temperature

    International Nuclear Information System (INIS)

    Wetzorke, I.; Karsch, F.; Laermann, E.; Petreczky, P.; Stickan, S.

    2001-10-01

    The Maximum Entropy Method provides a Bayesian approach to reconstruct the spectral functions from discrete points in Euclidean time. The applicability of the approach at finite temperature is probed with the thermal meson correlation function. Furthermore the influence of fuzzing/smearing techniques on the spectral shape is investigated. We present first results for meson spectral functions at several temperatures below and above T c . The correlation functions were obtained from quenched calculations with Clover fermions on large isotropic lattices of the size (24 - 64) 3 x 16. We compare the resulting pole masses with the ones obtained from standard 2-exponential fits of spatial and temporal correlation functions at finite temperature and in the vacuum. The deviation of the meson spectral functions from free spectral functions is examined above the critical temperature. (orig.)

  10. Meson spectral functions at finite temperature

    International Nuclear Information System (INIS)

    Wetzorke, I.; Karsch, F.; Laermann, E.; Petreczky, P.; Stickan, S.

    2002-01-01

    The Maximum Entropy Method provides a Bayesian approach to reconstruct the spectral functions from discrete points in Euclidean time. The applicability of the approach at finite temperature is probed with the thermal meson correlation function. Furthermore the influence of fuzzing/smearing techniques on the spectral shape is investigated. We present first results for meson spectral functions at several temperatures below and above T c . The correlation functions were obtained from quenched calculations with Clover fermions on large isotropic lattices of the size (24 - 64) 3 x 16. We compare the resulting pole masses with the ones obtained from standard 2-exponential fits of spatial and temporal correlation functions at finite temperature and in the vacuum. The deviation of the meson spectral functions from free spectral functions is examined above the critical temperature

  11. Meson spectral functions at finite temperature

    Energy Technology Data Exchange (ETDEWEB)

    Wetzorke, I.; Karsch, F.; Laermann, E.; Petreczky, P.; Stickan, S

    2002-03-01

    The Maximum Entropy Method provides a Bayesian approach to reconstruct the spectral functions from discrete points in Euclidean time. The applicability of the approach at finite temperature is probed with the thermal meson correlation function. Furthermore the influence of fuzzing/smearing techniques on the spectral shape is investigated. We present first results for meson spectral functions at several temperatures below and above T{sub c}. The correlation functions were obtained from quenched calculations with Clover fermions on large isotropic lattices of the size (24 - 64){sup 3} x 16. We compare the resulting pole masses with the ones obtained from standard 2-exponential fits of spatial and temporal correlation functions at finite temperature and in the vacuum. The deviation of the meson spectral functions from free spectral functions is examined above the critical temperature.

  12. Meson spectral functions at finite temperature

    Energy Technology Data Exchange (ETDEWEB)

    Wetzorke, I.; Karsch, F.; Laermann, E.; Petreczky, P.; Stickan, S. [Bielefeld Univ. (Germany). Fakultaet fuer Physik

    2001-10-01

    The Maximum Entropy Method provides a Bayesian approach to reconstruct the spectral functions from discrete points in Euclidean time. The applicability of the approach at finite temperature is probed with the thermal meson correlation function. Furthermore the influence of fuzzing/smearing techniques on the spectral shape is investigated. We present first results for meson spectral functions at several temperatures below and above T{sub c}. The correlation functions were obtained from quenched calculations with Clover fermions on large isotropic lattices of the size (24 - 64){sup 3} x 16. We compare the resulting pole masses with the ones obtained from standard 2-exponential fits of spatial and temporal correlation functions at finite temperature and in the vacuum. The deviation of the meson spectral functions from free spectral functions is examined above the critical temperature. (orig.)

  13. The development of a modified spectral ripple test.

    Science.gov (United States)

    Aronoff, Justin M; Landsberger, David M

    2013-08-01

    Poor spectral resolution can be a limiting factor for hearing impaired listeners, particularly for complex listening tasks such as speech understanding in noise. Spectral ripple tests are commonly used to measure spectral resolution, but these tests contain a number of potential confounds that can make interpretation of the results difficult. To measure spectral resolution while avoiding those confounds, a modified spectral ripple test with dynamically changing ripples was created, referred to as the spectral-temporally modulated ripple test (SMRT). This paper describes the SMRT and provides evidence that it is sensitive to changes in spectral resolution.

  14. Comparing auditory filter bandwidths, spectral ripple modulation detection, spectral ripple discrimination, and speech recognition: Normal and impaired hearing.

    Science.gov (United States)

    Davies-Venn, Evelyn; Nelson, Peggy; Souza, Pamela

    2015-07-01

    Some listeners with hearing loss show poor speech recognition scores in spite of using amplification that optimizes audibility. Beyond audibility, studies have suggested that suprathreshold abilities such as spectral and temporal processing may explain differences in amplified speech recognition scores. A variety of different methods has been used to measure spectral processing. However, the relationship between spectral processing and speech recognition is still inconclusive. This study evaluated the relationship between spectral processing and speech recognition in listeners with normal hearing and with hearing loss. Narrowband spectral resolution was assessed using auditory filter bandwidths estimated from simultaneous notched-noise masking. Broadband spectral processing was measured using the spectral ripple discrimination (SRD) task and the spectral ripple depth detection (SMD) task. Three different measures were used to assess unamplified and amplified speech recognition in quiet and noise. Stepwise multiple linear regression revealed that SMD at 2.0 cycles per octave (cpo) significantly predicted speech scores for amplified and unamplified speech in quiet and noise. Commonality analyses revealed that SMD at 2.0 cpo combined with SRD and equivalent rectangular bandwidth measures to explain most of the variance captured by the regression model. Results suggest that SMD and SRD may be promising clinical tools for diagnostic evaluation and predicting amplification outcomes.

  15. Comparing auditory filter bandwidths, spectral ripple modulation detection, spectral ripple discrimination, and speech recognition: Normal and impaired hearinga)

    Science.gov (United States)

    Davies-Venn, Evelyn; Nelson, Peggy; Souza, Pamela

    2015-01-01

    Some listeners with hearing loss show poor speech recognition scores in spite of using amplification that optimizes audibility. Beyond audibility, studies have suggested that suprathreshold abilities such as spectral and temporal processing may explain differences in amplified speech recognition scores. A variety of different methods has been used to measure spectral processing. However, the relationship between spectral processing and speech recognition is still inconclusive. This study evaluated the relationship between spectral processing and speech recognition in listeners with normal hearing and with hearing loss. Narrowband spectral resolution was assessed using auditory filter bandwidths estimated from simultaneous notched-noise masking. Broadband spectral processing was measured using the spectral ripple discrimination (SRD) task and the spectral ripple depth detection (SMD) task. Three different measures were used to assess unamplified and amplified speech recognition in quiet and noise. Stepwise multiple linear regression revealed that SMD at 2.0 cycles per octave (cpo) significantly predicted speech scores for amplified and unamplified speech in quiet and noise. Commonality analyses revealed that SMD at 2.0 cpo combined with SRD and equivalent rectangular bandwidth measures to explain most of the variance captured by the regression model. Results suggest that SMD and SRD may be promising clinical tools for diagnostic evaluation and predicting amplification outcomes. PMID:26233047

  16. ANALYZING SPECTRAL CHARACTERISTICS OF SHADOW AREA FROM ADS-40 HIGH RADIOMETRIC RESOLUTION AERIAL IMAGES

    Directory of Open Access Journals (Sweden)

    Y.-T. Hsieh

    2016-06-01

    Full Text Available The shadows in optical remote sensing images are regarded as image nuisances in numerous applications. The classification and interpretation of shadow area in a remote sensing image are a challenge, because of the reduction or total loss of spectral information in those areas. In recent years, airborne multispectral aerial image devices have been developed 12-bit or higher radiometric resolution data, including Leica ADS-40, Intergraph DMC. The increased radiometric resolution of digital imagery provides more radiometric details of potential use in classification or interpretation of land cover of shadow areas. Therefore, the objectives of this study are to analyze the spectral properties of the land cover in the shadow areas by ADS-40 high radiometric resolution aerial images, and to investigate the spectral and vegetation index differences between the various shadow and non-shadow land covers. According to research findings of spectral analysis of ADS-40 image: (i The DN values in shadow area are much lower than in nonshadow area; (ii DN values received from shadowed areas that will also be affected by different land cover, and it shows the possibility of land cover property retrieval as in nonshadow area; (iii The DN values received from shadowed regions decrease in the visible band from short to long wavelengths due to scattering; (iv The shadow area NIR of vegetation category also shows a strong reflection; (v Generally, vegetation indexes (NDVI still have utility to classify the vegetation and non-vegetation in shadow area. The spectral data of high radiometric resolution images (ADS-40 is potential for the extract land cover information of shadow areas.

  17. Spectral properties of generalized eigenparameter dependent ...

    African Journals Online (AJOL)

    Jost function, spectrum, the spectral singularities, and the properties of the principal vectors corresponding to the spectral singularities of L, if. ∞Σn=1 n(∣1 - an∣ + ∣bnl) < ∞. Mathematics Subject Classication (2010): 34L05, 34L40, 39A70, 47A10, 47A75. Key words: Discrete equations, eigenparameter, spectral analysis, ...

  18. Planck 2013 results. IX. HFI spectral response

    CERN Document Server

    Ade, P A R; Armitage-Caplan, C; Arnaud, M; Ashdown, M; Atrio-Barandela, F; Aumont, J; Baccigalupi, C; Banday, A J; Barreiro, R B; Battaner, E; Benabed, K; Benoît, A; Benoit-Lévy, A; Bernard, J -P; Bersanelli, M; Bielewicz, P; Bobin, J; Bock, J J; Bond, J R; Borrill, J; Bouchet, F R; Boulanger, F; Bridges, M; Bucher, M; Burigana, C; Cardoso, J -F; Catalano, A; Challinor, A; Chamballu, A; Chary, R -R; Chen, X; Chiang, L -Y; Chiang, H C; Christensen, P R; Church, S; Clements, D L; Colombi, S; Colombo, L P L; Combet, C; Comis, B; Couchot, F; Coulais, A; Crill, B P; Curto, A; Cuttaia, F; Danese, L; Davies, R D; de Bernardis, P; de Rosa, A; de Zotti, G; Delabrouille, J; Delouis, J -M; Désert, F -X; Dickinson, C; Diego, J M; Dole, H; Donzelli, S; Doré, O; Douspis, M; Dupac, X; Efstathiou, G; Enßlin, T A; Eriksen, H K; Falgarone, E; Finelli, F; Forni, O; Frailis, M; Franceschi, E; Galeotta, S; Ganga, K; Giard, M; Giraud-Héraud, Y; González-Nuevo, J; Górski, K M; Gratton, S; Gregorio, A; Gruppuso, A; Hansen, F K; Hanson, D; Harrison, D; Henrot-Versillé, S; Hernández-Monteagudo, C; Herranz, D; Hildebrandt, S R; Hivon, E; Hobson, M; Holmes, W A; Hornstrup, A; Hovest, W; Huffenberger, K M; Hurier, G; Jaffe, T R; Jaffe, A H; Jones, W C; Juvela, M; Keihänen, E; Keskitalo, R; Kisner, T S; Kneissl, R; Knoche, J; Knox, L; Kunz, M; Kurki-Suonio, H; Lagache, G; Lamarre, J -M; Lasenby, A; Laureijs, R J; Lawrence, C R; Leahy, J P; Leonardi, R; Leroy, C; Lesgourgues, J; Liguori, M; Lilje, P B; Linden-Vørnle, M; López-Caniego, M; Lubin, P M; Macías-Pérez, J F; Maffei, B; Mandolesi, N; Maris, M; Marshall, D J; Martin, P G; Martínez-González, E; Masi, S; Matarrese, S; Matthai, F; Mazzotta, P; McGehee, P; Melchiorri, A; Mendes, L; Mennella, A; Migliaccio, M; Mitra, S; Miville-Deschênes, M -A; Moneti, A; Montier, L; Morgante, G; Mortlock, D; Munshi, D; Murphy, J A; Naselsky, P; Nati, F; Natoli, P; Netterfield, C B; Nørgaard-Nielsen, H U; North, C; Noviello, F; Novikov, D; Novikov, I; Osborne, S; Oxborrow, C A; Paci, F; Pagano, L; Pajot, F; Paoletti, D; Pasian, F; Patanchon, G; Perdereau, O; Perotto, L; Perrotta, F; Piacentini, F; Piat, M; Pierpaoli, E; Pietrobon, D; Plaszczynski, S; Pointecouteau, E; Polenta, G; Ponthieu, N; Popa, L; Poutanen, T; Pratt, G W; Prézeau, G; Prunet, S; Puget, J -L; Rachen, J P; Reinecke, M; Remazeilles, M; Renault, C; Ricciardi, S; Riller, T; Ristorcelli, I; Rocha, G; Rosset, C; Roudier, G; Rusholme, B; Santos, D; Savini, G; Shellard, E P S; Spencer, L D; Starck, J -L; Stolyarov, V; Stompor, R; Sudiwala, R; Sureau, F; Sutton, D; Suur-Uski, A -S; Sygnet, J -F; Tauber, J A; Tavagnacco, D; Terenzi, L; Tomasi, M; Tristram, M; Tucci, M; Umana, G; Valenziano, L; Valiviita, J; Van Tent, B; Vielva, P; Villa, F; Vittorio, N; Wade, L A; Wandelt, B D; Yvon, D; Zacchei, A; Zonca, A

    2014-01-01

    The Planck High Frequency Instrument (HFI) spectral response was determined through a series of ground based tests conducted with the HFI focal plane in a cryogenic environment prior to launch. The main goal of the spectral transmission tests was to measure the relative spectral response (including out-of-band signal rejection) of all HFI detectors. This was determined by measuring the output of a continuously scanned Fourier transform spectrometer coupled with all HFI detectors. As there is no on-board spectrometer within HFI, the ground-based spectral response experiments provide the definitive data set for the relative spectral calibration of the HFI. The spectral response of the HFI is used in Planck data analysis and component separation, this includes extraction of CO emission observed within Planck bands, dust emission, Sunyaev-Zeldovich sources, and intensity to polarization leakage. The HFI spectral response data have also been used to provide unit conversion and colour correction analysis tools. Ver...

  19. CRISS power spectral density

    International Nuclear Information System (INIS)

    Vaeth, W.

    1979-04-01

    The correlation of signal components at different frequencies like higher harmonics cannot be detected by a normal power spectral density measurement, since this technique correlates only components at the same frequency. This paper describes a special method for measuring the correlation of two signal components at different frequencies: the CRISS power spectral density. From this new function in frequency analysis, the correlation of two components can be determined quantitatively either they stem from one signal or from two diverse signals. The principle of the method, suitable for the higher harmonics of a signal as well as for any other frequency combinations is shown for the digital frequency analysis technique. Two examples of CRISS power spectral densities demonstrates the operation of the new method. (orig.) [de

  20. Onboard spectral imager data processor

    Science.gov (United States)

    Otten, Leonard J.; Meigs, Andrew D.; Franklin, Abraham J.; Sears, Robert D.; Robison, Mark W.; Rafert, J. Bruce; Fronterhouse, Donald C.; Grotbeck, Ronald L.

    1999-10-01

    Previous papers have described the concept behind the MightySat II.1 program, the satellite's Fourier Transform imaging spectrometer's optical design, the design for the spectral imaging payload, and its initial qualification testing. This paper discusses the on board data processing designed to reduce the amount of downloaded data by an order of magnitude and provide a demonstration of a smart spaceborne spectral imaging sensor. Two custom components, a spectral imager interface 6U VME card that moves data at over 30 MByte/sec, and four TI C-40 processors mounted to a second 6U VME and daughter card, are used to adapt the sensor to the spacecraft and provide the necessary high speed processing. A system architecture that offers both on board real time image processing and high-speed post data collection analysis of the spectral data has been developed. In addition to the on board processing of the raw data into a usable spectral data volume, one feature extraction technique has been incorporated. This algorithm operates on the basic interferometric data. The algorithm is integrated within the data compression process to search for uploadable feature descriptions.

  1. Using GIS servers and interactive maps in spectral data sharing and administration: Case study of Ahvaz Spectral Geodatabase Platform (ASGP)

    Science.gov (United States)

    Karami, Mojtaba; Rangzan, Kazem; Saberi, Azim

    2013-10-01

    With emergence of air-borne and space-borne hyperspectral sensors, spectroscopic measurements are gaining more importance in remote sensing. Therefore, the number of available spectral reference data is constantly increasing. This rapid increase often exhibits a poor data management, which leads to ultimate isolation of data on disk storages. Spectral data without precise description of the target, methods, environment, and sampling geometry cannot be used by other researchers. Moreover, existing spectral data (in case it accompanied with good documentation) become virtually invisible or unreachable for researchers. Providing documentation and a data-sharing framework for spectral data, in which researchers are able to search for or share spectral data and documentation, would definitely improve the data lifetime. Relational Database Management Systems (RDBMS) are main candidates for spectral data management and their efficiency is proven by many studies and applications to date. In this study, a new approach to spectral data administration is presented based on spatial identity of spectral samples. This method benefits from scalability and performance of RDBMS for storage of spectral data, but uses GIS servers to provide users with interactive maps as an interface to the system. The spectral files, photographs and descriptive data are considered as belongings of a geospatial object. A spectral processing unit is responsible for evaluation of metadata quality and performing routine spectral processing tasks for newly-added data. As a result, by using internet browser software the users would be able to visually examine availability of data and/or search for data based on descriptive attributes associated to it. The proposed system is scalable and besides giving the users good sense of what data are available in the database, it facilitates participation of spectral reference data in producing geoinformation.

  2. Wind Noise Reduction using Non-negative Sparse Coding

    DEFF Research Database (Denmark)

    Schmidt, Mikkel N.; Larsen, Jan; Hsiao, Fu-Tien

    2007-01-01

    We introduce a new speaker independent method for reducing wind noise in single-channel recordings of noisy speech. The method is based on non-negative sparse coding and relies on a wind noise dictionary which is estimated from an isolated noise recording. We estimate the parameters of the model ...... and discuss their sensitivity. We then compare the algorithm with the classical spectral subtraction method and the Qualcomm-ICSI-OGI noise reduction method. We optimize the sound quality in terms of signal-to-noise ratio and provide results on a noisy speech recognition task....

  3. Precise Multi-Spectral Dermatological Imaging

    DEFF Research Database (Denmark)

    Gomez, David Delgado; Carstensen, Jens Michael; Ersbøll, Bjarne Kjær

    2004-01-01

    In this work, an integrated imaging system to obtain accurate and reproducible multi-spectral dermatological images is proposed. The system is made up of an integrating sphere, light emitting diodes and a generic monochromatic camera. The system can collect up to 10 different spectral bands....... These spectral bands vary from ultraviolet to near infrared. The welldefined and diffuse illumination of the optically closed scene aims to avoid shadows and specular reflections. Furthermore, the system has been developed to guarantee the reproducibility of the collected images. This allows for comparative...

  4. Jet Noise Reduction by Microjets - A Parametric Study

    Science.gov (United States)

    Zaman, K. B. M. Q.

    2010-01-01

    The effect of injecting tiny secondary jets (microjets ) on the radiated noise from a subsonic primary jet is studied experimentally. The microjets are injected on to the primary jet near the nozzle exit with variable port geometry, working fluid and driving pressure. A clear noise reduction is observed that improves with increasing jet pressure. It is found that smaller diameter ports with higher driving pressure, but involving less thrust and mass fraction, can produce better noise reduction. A collection of data from the present as well as past experiments is examined in an attempt to correlate the noise reduction with the operating parameters. The results indicate that turbulent mixing noise reduction, as monitored by OASPL at a shallow angle, correlates with the ratio of jet to primary jet driving pressures normalized by the ratio of corresponding diameters (p d /pjD). With gaseous injection, the spectral amplitudes decrease at lower frequencies while an increase is noted at higher frequencies. It is apparent that this amplitude crossover is at least partly due to shock-associated noise from the underexpanded jets themselves. Such crossover is not seen with water injection since the flow in that case is incompressible and there is no shock-associated noise. Centerline velocity data show that larger noise reduction is accompanied by faster jet decay as well as significant reduction in turbulence intensities. While a physical understanding of the dependence of noise reduction on p d /pjD remains unclear, given this correlation, an analysis explains the observed dependence of the effect on various other parameters.

  5. A comprehensive spectral theory of zonal-mode dynamics in trapped electron mode turbulence

    International Nuclear Information System (INIS)

    Terry, P.W.; Gatto, R.; Baver, D.A.; Fernandez, E.

    2005-01-01

    A comprehensive, self-consistent theory for spectral dynamics in trapped electron mode (TEM) turbulence offers critical new understanding and insights into zonal-mode physics. This theory shows that 1) zonal mode structure, anisotropy, excitation, and temporal behavior arise at and from the interface of nonlinear advection and linear wave properties; 2) waves induce a marked spectral energy-transfer anisotropy that preferentially drives zonal modes relative to non zonal modes; 3) triplet correlations involving density (as opposed to those involving only flow) mediate the dominant energy transfer at long wavelengths; 4) energy transfer becomes inverse in the presence of wave anisotropy, where otherwise it is forward; 5) zonal-mode excitation is accompanied by excitation of a spectrum of damped eigenmodes, making zonal modes nonlinearly damped; and 6) the combination of anisotropic transfer to zonal modes and their nonlinear damping make this the dominant saturation mechanism for TEM turbulence. This accounts for the reduction of turbulence level by zonal modes, not zonal-flow ExB shearing. (author)

  6. 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

  7. Curvature Effect and the Spectral Softening Phenomenon Detected ...

    Indian Academy of Sciences (India)

    soft spectral evolution, indicating that this spectral softening is not a rare phenomenon .... of time, there exists a temporal steep decay phase accompanied by spectral softening. (d) In most cases, the temporal power law index α and the spectral.

  8. Spectral properties of 441 radio pulsars

    Science.gov (United States)

    Jankowski, F.; van Straten, W.; Keane, E. F.; Bailes, M.; Barr, E. D.; Johnston, S.; Kerr, M.

    2018-02-01

    We present a study of the spectral properties of 441 pulsars observed with the Parkes radio telescope near the centre frequencies of 728, 1382 and 3100 MHz. The observations at 728 and 3100 MHz were conducted simultaneously using the dual-band 10-50 cm receiver. These high-sensitivity, multifrequency observations provide a systematic and uniform sample of pulsar flux densities. We combine our measurements with spectral data from the literature in order to derive the spectral properties of these pulsars. Using techniques from robust regression and information theory, we classify the observed spectra in an objective, robust and unbiased way into five morphological classes: simple or broken power law, power law with either low- or high-frequency cut-off and log-parabolic spectrum. While about 79 per cent of the pulsars that could be classified have simple power-law spectra, we find significant deviations in 73 pulsars, 35 of which have curved spectra, 25 with a spectral break and 10 with a low-frequency turn-over. We identify 11 gigahertz-peaked spectrum (GPS) pulsars, with 3 newly identified in this work and 8 confirmations of known GPS pulsars; 3 others show tentative evidence of GPS, but require further low-frequency measurements to support this classification. The weighted mean spectral index of all pulsars with simple power-law spectra is -1.60 ± 0.03. The observed spectral indices are well described by a shifted log-normal distribution. The strongest correlations of spectral index are with spin-down luminosity, magnetic field at the light-cylinder and spin-down rate. We also investigate the physical origin of the observed spectral features and determine emission altitudes for three pulsars.

  9. THE DATA REDUCTION PIPELINE FOR THE APACHE POINT OBSERVATORY GALACTIC EVOLUTION EXPERIMENT

    International Nuclear Information System (INIS)

    Nidever, David L.; Holtzman, Jon A.; Prieto, Carlos Allende; Mészáros, Szabolcs; Beland, Stephane; Bender, Chad; Desphande, Rohit; Bizyaev, Dmitry; Burton, Adam; García Pérez, Ana E.; Hearty, Fred R.; Majewski, Steven R.; Skrutskie, Michael F.; Sobeck, Jennifer S.; Wilson, John C.; Fleming, Scott W.; Muna, Demitri; Nguyen, Duy; Schiavon, Ricardo P.; Shetrone, Matthew

    2015-01-01

    The Apache Point Observatory Galactic Evolution Experiment (APOGEE), part of the Sloan Digital Sky Survey III, explores the stellar populations of the Milky Way using the Sloan 2.5-m telescope linked to a high resolution (R ∼ 22,500), near-infrared (1.51–1.70 μm) spectrograph with 300 optical fibers. For over 150,000 predominantly red giant branch stars that APOGEE targeted across the Galactic bulge, disks and halo, the collected high signal-to-noise ratio (>100 per half-resolution element) spectra provide accurate (∼0.1 km s −1 ) RVs, stellar atmospheric parameters, and precise (≲0.1 dex) chemical abundances for about 15 chemical species. Here we describe the basic APOGEE data reduction software that reduces multiple 3D raw data cubes into calibrated, well-sampled, combined 1D spectra, as implemented for the SDSS-III/APOGEE data releases (DR10, DR11 and DR12). The processing of the near-IR spectral data of APOGEE presents some challenges for reduction, including automated sky subtraction and telluric correction over a 3°-diameter field and the combination of spectrally dithered spectra. We also discuss areas for future improvement

  10. THE DATA REDUCTION PIPELINE FOR THE APACHE POINT OBSERVATORY GALACTIC EVOLUTION EXPERIMENT

    Energy Technology Data Exchange (ETDEWEB)

    Nidever, David L. [Department of Astronomy, University of Michigan, Ann Arbor, MI 48109 (United States); Holtzman, Jon A. [New Mexico State University, Las Cruces, NM 88003 (United States); Prieto, Carlos Allende; Mészáros, Szabolcs [Instituto de Astrofísica de Canarias, Via Láctea s/n, E-38205 La Laguna, Tenerife (Spain); Beland, Stephane [Laboratory for Atmospheric and Space Sciences, University of Colorado at Boulder, Boulder, CO (United States); Bender, Chad; Desphande, Rohit [Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA 16802 (United States); Bizyaev, Dmitry [Apache Point Observatory and New Mexico State University, P.O. Box 59, sunspot, NM 88349-0059 (United States); Burton, Adam; García Pérez, Ana E.; Hearty, Fred R.; Majewski, Steven R.; Skrutskie, Michael F.; Sobeck, Jennifer S.; Wilson, John C. [Department of Astronomy, University of Virginia, Charlottesville, VA 22904-4325 (United States); Fleming, Scott W. [Computer Sciences Corporation, 3700 San Martin Dr, Baltimore, MD 21218 (United States); Muna, Demitri [Department of Astronomy and the Center for Cosmology and Astro-Particle Physics, The Ohio State University, Columbus, OH 43210 (United States); Nguyen, Duy [Department of Astronomy and Astrophysics, University of Toronto, Toronto, Ontario, M5S 3H4 (Canada); Schiavon, Ricardo P. [Gemini Observatory, 670 N. A’Ohoku Place, Hilo, HI 96720 (United States); Shetrone, Matthew, E-mail: dnidever@umich.edu [University of Texas at Austin, McDonald Observatory, Fort Davis, TX 79734 (United States)

    2015-12-15

    The Apache Point Observatory Galactic Evolution Experiment (APOGEE), part of the Sloan Digital Sky Survey III, explores the stellar populations of the Milky Way using the Sloan 2.5-m telescope linked to a high resolution (R ∼ 22,500), near-infrared (1.51–1.70 μm) spectrograph with 300 optical fibers. For over 150,000 predominantly red giant branch stars that APOGEE targeted across the Galactic bulge, disks and halo, the collected high signal-to-noise ratio (>100 per half-resolution element) spectra provide accurate (∼0.1 km s{sup −1}) RVs, stellar atmospheric parameters, and precise (≲0.1 dex) chemical abundances for about 15 chemical species. Here we describe the basic APOGEE data reduction software that reduces multiple 3D raw data cubes into calibrated, well-sampled, combined 1D spectra, as implemented for the SDSS-III/APOGEE data releases (DR10, DR11 and DR12). The processing of the near-IR spectral data of APOGEE presents some challenges for reduction, including automated sky subtraction and telluric correction over a 3°-diameter field and the combination of spectrally dithered spectra. We also discuss areas for future improvement.

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

    International Nuclear Information System (INIS)

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

    1984-01-01

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

  12. The Sturm-Liouville inverse spectral problem with boundary conditions depending on the spectral parameter

    Directory of Open Access Journals (Sweden)

    Cornelis van der Mee

    2005-01-01

    Full Text Available We present the complete version including proofs of the results announced in [van der Mee C., Pivovarchik V.: A Sturm-Liouville spectral problem with boundary conditions depending on the spectral parameter. Funct. Anal. Appl. 36 (2002, 315–317 [Funkts. Anal. Prilozh. 36 (2002, 74–77 (Russian

  13. Spectrally-engineered solar thermal photovoltaic devices

    Science.gov (United States)

    Lenert, Andrej; Bierman, David; Chan, Walker; Celanovic, Ivan; Soljacic, Marin; Wang, Evelyn N.; Nam, Young Suk; McEnaney, Kenneth; Kraemer, Daniel; Chen, Gang

    2018-03-27

    A solar thermal photovoltaic device, and method of forming same, includes a solar absorber and a spectrally selective emitter formed on either side of a thermally conductive substrate. The solar absorber is configured to absorb incident solar radiation. The solar absorber and the spectrally selective emitter are configured with an optimized emitter-to-absorber area ratio. The solar thermal photovoltaic device also includes a photovoltaic cell in thermal communication with the spectrally selective emitter. The spectrally selective emitter is configured to permit high emittance for energies above a bandgap of the photovoltaic cell and configured to permit low emittance for energies below the bandgap.

  14. Spacetime Discontinuous Galerkin FEM: Spectral Response

    International Nuclear Information System (INIS)

    Abedi, R; Omidi, O; Clarke, P L

    2014-01-01

    Materials in nature demonstrate certain spectral shapes in terms of their material properties. Since successful experimental demonstrations in 2000, metamaterials have provided a means to engineer materials with desired spectral shapes for their material properties. Computational tools are employed in two different aspects for metamaterial modeling: 1. Mircoscale unit cell analysis to derive and possibly optimize material's spectral response; 2. macroscale to analyze their interaction with conventional material. We compare two different approaches of Time-Domain (TD) and Frequency Domain (FD) methods for metamaterial applications. Finally, we discuss advantages of the TD method of Spacetime Discontinuous Galerkin finite element method (FEM) for spectral analysis of metamaterials

  15. Spectral quality requirements for effluent identification

    Science.gov (United States)

    Czerwinski, R. N.; Seeley, J. A.; Wack, E. C.

    2005-11-01

    We consider the problem of remotely identifying gaseous materials using passive sensing of long-wave infrared (LWIR) spectral features at hyperspectral resolution. Gaseous materials are distinguishable in the LWIR because of their unique spectral fingerprints. A sensor degraded in capability by noise or limited spectral resolution, however, may be unable to positively identify contaminants, especially if they are present in low concentrations or if the spectral library used for comparisons includes materials with similar spectral signatures. This paper will quantify the relative importance of these parameters and express the relationships between them in a functional form which can be used as a rule of thumb in sensor design or in assessing sensor capability for a specific task. This paper describes the simulation of remote sensing datacontaining a gas cloud.In each simulation, the spectra are degraded in spectral resolution and through the addition of noise to simulate spectra collected by sensors of varying design and capability. We form a trade space by systematically varying the number of sensor spectral channels and signal-to-noise ratio over a range of values. For each scenario, we evaluate the capability of the sensor for gas identification by computing the ratio of the F-statistic for the truth gas tothe same statistic computed over the rest of the library.The effect of the scope of the library is investigated as well, by computing statistics on the variability of the identification capability as the library composition is varied randomly.

  16. Information-efficient spectral imaging sensor

    Science.gov (United States)

    Sweatt, William C.; Gentry, Stephen M.; Boye, Clinton A.; Grotbeck, Carter L.; Stallard, Brian R.; Descour, Michael R.

    2003-01-01

    A programmable optical filter for use in multispectral and hyperspectral imaging. The filter splits the light collected by an optical telescope into two channels for each of the pixels in a row in a scanned image, one channel to handle the positive elements of a spectral basis filter and one for the negative elements of the spectral basis filter. Each channel for each pixel disperses its light into n spectral bins, with the light in each bin being attenuated in accordance with the value of the associated positive or negative element of the spectral basis vector. The spectral basis vector is constructed so that its positive elements emphasize the presence of a target and its negative elements emphasize the presence of the constituents of the background of the imaged scene. The attenuated light in the channels is re-imaged onto separate detectors for each pixel and then the signals from the detectors are combined to give an indication of the presence or not of the target in each pixel of the scanned scene. This system provides for a very efficient optical determination of the presence of the target, as opposed to the very data intensive data manipulations that are required in conventional hyperspectral imaging systems.

  17. Spectral theory of linear operators and spectral systems in Banach algebras

    CERN Document Server

    Müller, Vladimir

    2003-01-01

    This book is dedicated to the spectral theory of linear operators on Banach spaces and of elements in Banach algebras. It presents a survey of results concerning various types of spectra, both of single and n-tuples of elements. Typical examples are the one-sided spectra, the approximate point, essential, local and Taylor spectrum, and their variants. The theory is presented in a unified, axiomatic and elementary way. Many results appear here for the first time in a monograph. The material is self-contained. Only a basic knowledge of functional analysis, topology, and complex analysis is assumed. The monograph should appeal both to students who would like to learn about spectral theory and to experts in the field. It can also serve as a reference book. The present second edition contains a number of new results, in particular, concerning orbits and their relations to the invariant subspace problem. This book is dedicated to the spectral theory of linear operators on Banach spaces and of elements in Banach alg...

  18. Developement of the method for realization of spectral irradiance scale featuring system of spectral comparisons

    International Nuclear Information System (INIS)

    Skerovic, V; Zarubica, V; Aleksic, M; Zekovic, L; Belca, I

    2010-01-01

    Realization of the scale of spectral responsivity of the detectors in the Directorate of Measures and Precious Metals (DMDM) is based on silicon detectors traceable to LNE-INM. In order to realize the unit of spectral irradiance in the laboratory for photometry and radiometry of the Bureau of Measures and Precious Metals, the new method based on the calibration of the spectroradiometer by comparison with standard detector has been established. The development of the method included realization of the System of Spectral Comparisons (SSC), together with the detector spectral responsivity calibrations by means of a primary spectrophotometric system. The linearity testing and stray light analysis were preformed to characterize the spectroradiometer. Measurement of aperture diameter and calibration of transimpedance amplifier were part of the overall experiment. In this paper, the developed method is presented and measurement results with the associated measurement uncertainty budget are shown.

  19. Developement of the method for realization of spectral irradiance scale featuring system of spectral comparisons

    Energy Technology Data Exchange (ETDEWEB)

    Skerovic, V; Zarubica, V; Aleksic, M [Directorate of measures and precious metals, Optical radiation Metrology department, Mike Alasa 14, 11000 Belgrade (Serbia); Zekovic, L; Belca, I, E-mail: vladanskerovic@dmdm.r [Faculty of Physics, Department for Applied physics and metrology, Studentski trg 12-16, 11000 Belgrade (Serbia)

    2010-10-15

    Realization of the scale of spectral responsivity of the detectors in the Directorate of Measures and Precious Metals (DMDM) is based on silicon detectors traceable to LNE-INM. In order to realize the unit of spectral irradiance in the laboratory for photometry and radiometry of the Bureau of Measures and Precious Metals, the new method based on the calibration of the spectroradiometer by comparison with standard detector has been established. The development of the method included realization of the System of Spectral Comparisons (SSC), together with the detector spectral responsivity calibrations by means of a primary spectrophotometric system. The linearity testing and stray light analysis were preformed to characterize the spectroradiometer. Measurement of aperture diameter and calibration of transimpedance amplifier were part of the overall experiment. In this paper, the developed method is presented and measurement results with the associated measurement uncertainty budget are shown.

  20. Cochlear implant users' spectral ripple resolution.

    Science.gov (United States)

    Jeon, Eun Kyung; Turner, Christopher W; Karsten, Sue A; Henry, Belinda A; Gantz, Bruce J

    2015-10-01

    This study revisits the issue of the spectral ripple resolution abilities of cochlear implant (CI) users. The spectral ripple resolution of recently implanted CI recipients (implanted during the last 10 years) were compared to those of CI recipients implanted 15 to 20 years ago, as well as those of normal-hearing and hearing-impaired listeners from previously published data from Henry, Turner, and Behrens [J. Acoust. Soc. Am. 118, 1111-1121 (2005)]. More recently, implanted CI recipients showed significantly better spectral ripple resolution. There is no significant difference in spectral ripple resolution for these recently implanted subjects compared to hearing-impaired (acoustic) listeners. The more recently implanted CI users had significantly better pre-operative speech perception than previously reported CI users. These better pre-operative speech perception scores in CI users from the current study may be related to better performance on the spectral ripple discrimination task; however, other possible factors such as improvements in internal and external devices cannot be excluded.

  1. Spectral dimension in causal set quantum gravity

    International Nuclear Information System (INIS)

    Eichhorn, Astrid; Mizera, Sebastian

    2014-01-01

    We evaluate the spectral dimension in causal set quantum gravity by simulating random walks on causal sets. In contrast to other approaches to quantum gravity, we find an increasing spectral dimension at small scales. This observation can be connected to the nonlocality of causal set theory that is deeply rooted in its fundamentally Lorentzian nature. Based on its large-scale behaviour, we conjecture that the spectral dimension can serve as a tool to distinguish causal sets that approximate manifolds from those that do not. As a new tool to probe quantum spacetime in different quantum gravity approaches, we introduce a novel dimensional estimator, the causal spectral dimension, based on the meeting probability of two random walkers, which respect the causal structure of the quantum spacetime. We discuss a causal-set example, where the spectral dimension and the causal spectral dimension differ, due to the existence of a preferred foliation. (paper)

  2. A Simple Spectral Observer

    Directory of Open Access Journals (Sweden)

    Lizeth Torres

    2018-05-01

    Full Text Available The principal aim of a spectral observer is twofold: the reconstruction of a signal of time via state estimation and the decomposition of such a signal into the frequencies that make it up. A spectral observer can be catalogued as an online algorithm for time-frequency analysis because is a method that can compute on the fly the Fourier transform (FT of a signal, without having the entire signal available from the start. In this regard, this paper presents a novel spectral observer with an adjustable constant gain for reconstructing a given signal by means of the recursive identification of the coefficients of a Fourier series. The reconstruction or estimation of a signal in the context of this work means to find the coefficients of a linear combination of sines a cosines that fits a signal such that it can be reproduced. The design procedure of the spectral observer is presented along with the following applications: (1 the reconstruction of a simple periodical signal, (2 the approximation of both a square and a triangular signal, (3 the edge detection in signals by using the Fourier coefficients, (4 the fitting of the historical Bitcoin market data from 1 December 2014 to 8 January 2018 and (5 the estimation of a input force acting upon a Duffing oscillator. To round out this paper, we present a detailed discussion about the results of the applications as well as a comparative analysis of the proposed spectral observer vis-à-vis the Short Time Fourier Transform (STFT, which is a well-known method for time-frequency analysis.

  3. Spectral characterization of natural backgrounds

    Science.gov (United States)

    Winkelmann, Max

    2017-10-01

    As the distribution and use of hyperspectral sensors is constantly increasing, the exploitation of spectral features is a threat for camouflaged objects. To improve camouflage materials at first the spectral behavior of backgrounds has to be known to adjust and optimize the spectral reflectance of camouflage materials. In an international effort, the NATO CSO working group SCI-295 "Development of Methods for Measurements and Evaluation of Natural Background EO Signatures" is developing a method how this characterization of backgrounds has to be done. It is obvious that the spectral characterization of a background will be quite an effort. To compare and exchange data internationally the measurements will have to be done in a similar way. To test and further improve this method an international field trial has been performed in Storkow, Germany. In the following we present first impressions and lessons learned from this field campaign and describe the data that has been measured.

  4. Substitution dynamical systems spectral analysis

    CERN Document Server

    Queffélec, Martine

    2010-01-01

    This volume mainly deals with the dynamics of finitely valued sequences, and more specifically, of sequences generated by substitutions and automata. Those sequences demonstrate fairly simple combinatorical and arithmetical properties and naturally appear in various domains. As the title suggests, the aim of the initial version of this book was the spectral study of the associated dynamical systems: the first chapters consisted in a detailed introduction to the mathematical notions involved, and the description of the spectral invariants followed in the closing chapters. This approach, combined with new material added to the new edition, results in a nearly self-contained book on the subject. New tools - which have also proven helpful in other contexts - had to be developed for this study. Moreover, its findings can be concretely applied, the method providing an algorithm to exhibit the spectral measures and the spectral multiplicity, as is demonstrated in several examples. Beyond this advanced analysis, many...

  5. A study of the temporal and spectral characteristics of gamma ray bursts

    International Nuclear Information System (INIS)

    Norris, J.

    1983-05-01

    Gamma-ray burst data obtained from the ISEE-3 Gamma Ray Burst Spectrometer and the Solar Maximum Mission's Hard X-ray Burst Spectrometer (HXRBS) were analyzed to yield information on burst temporal and spectral characteristics. A Monte Carlo approach was used to simulate the HXRBS response to candidate spectral models. At energies above about 100 keV, the spectra are well fit by exponential forms. At lower energies, 30 keV to 60 keV, depressions below the model continua are apparent in some bursts. The depressions are not instrumental or data-reduction artifacts. The event selection criterion of the ISEE-3 experiment is based on the time to accumulate a present number of photons rather than the photon count per unit time and is consequently independent of event duration for a given burst intensity, unlike most conventional systems. As a result, a significantly greater percentage of fast, narrow events have been detected. The ratio of count rates from two ISEE-3 detectors indicates that bursts with durations or aprox. one second have much softer spectra than longer bursts

  6. Camouflage in thermal IR: spectral design

    Science.gov (United States)

    Pohl, Anna; Fagerström, Jan; Kariis, Hans; Lindell, Roland; Hallberg, Tomas; Högström, Herman

    2016-10-01

    In this work a spectral designed coating from SPECTROGON is evaluated. Spectral design in this case means that the coating has a reflectivity equal to one at 3-5 and 8-12 microns were sensors operate and a much lower reflectivity in the other wave length regions. Three boxes are evaluated: one metallic, one black-body and one with a spectral designed surface, all with a 15 W radiator inside the box. It is shown that the box with the spectral designed surface can combine the two good characteristics of the other boxes: low signature from the metallic box and reasonable inside temperature from the black-body box. The measurements were verified with calculations using RadThermIR.

  7. Light distribution system comprising spectral conversion means

    DEFF Research Database (Denmark)

    2012-01-01

    , longer wavelength,a spectral conversion characteristics of the spectral conversion fibre being essentially determined by the spectral absorption and emission properties of the photoluminescent agent, the amount of photo- luminescent agent,and the distribution of the photoluminescent agent in the spectral......System (200, 300) for the distribution of white light, having a supply side (201, 301, 401) and a delivery side (202, 302, 402), the system being configured for guiding light with a multitude of visible wavelengths in a propagation direction P from the supply side to the distribution side...... of providing a light distribution system and a method of correcting the spectral transmission characteristics of a light distribution system are disclosed....

  8. Parametric Explosion Spectral Model

    Energy Technology Data Exchange (ETDEWEB)

    Ford, S R; Walter, W R

    2012-01-19

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

  9. [Modeling and Simulation of Spectral Polarimetric BRDF].

    Science.gov (United States)

    Ling, Jin-jiang; Li, Gang; Zhang, Ren-bin; Tang, Qian; Ye, Qiu

    2016-01-01

    Under the conditions of the polarized light, The reflective surface of the object is affected by many factors, refractive index, surface roughness, and so the angle of incidence. For the rough surface in the different wavelengths of light exhibit different reflection characteristics of polarization, a spectral polarimetric BRDF based on Kirchhof theory is proposee. The spectral model of complex refraction index is combined with refraction index and extinction coefficient spectral model which were got by using the known complex refraction index at different value. Then get the spectral model of surface roughness derived from the classical surface roughness measuring method combined with the Fresnel reflection function. Take the spectral model of refraction index and roughness into the BRDF model, then the spectral polarimetirc BRDF model is proposed. Compare the simulation results of the refractive index varies with wavelength, roughness is constant, the refraction index and roughness both vary with wavelength and origin model with other papers, it shows that, the spectral polarimetric BRDF model can show the polarization characteristics of the surface accurately, and can provide a reliable basis for the application of polarization remote sensing, and other aspects of the classification of substances.

  10. Spectral Line Shapes in Plasmas and Gases

    International Nuclear Information System (INIS)

    Oks, E.; Dalimier, D.; Stamm, R.; Stehle, CH.; Gonzalez, M.A.

    2011-01-01

    The subject of spectral line shapes (SLS), a.k.a. spectral line broadening, which embraces both shapes and shifts of spectral lines, is of both fundamental and practical importance. On the fundamental side, the study of the spectral line profiles reveals the underlying atomic and molecular interactions. On the practical side, the spectral line profiles are employed as powerful diagnostic tools for various media, such as neutral gases, technological gas discharges, magnetically confined plasmas for fusion, laser- and Z-pinch-produced plasmas (for fusion and other purposes), astrophysical plasmas (most importantly, solar plasmas), and planetary atmospheres. The research area covered by this special issue includes both the SLS dominated by various electric fields (including electron and ion micro fields in strongly ionized plasmas) and the SLS controlled by neutral particles. In the physical slang, the former is called plasma broadening while the latter is called neutral broadening (of course, the results of neutral broadening apply also to the spectral line broadening in neutral gases)

  11. Special function solutions of a spectral problem for a nonlinear quantum oscillator

    International Nuclear Information System (INIS)

    Schulze-Halberg, A; Morris, J R

    2012-01-01

    We construct exact solutions of a spectral problem involving the Schrödinger equation for a nonlinear, one-parameter oscillator potential. In contrast to a previous analysis of the problem (Carinena et al 2007 Ann. Phys. 322 434–59), where solutions were given through a Rodrigues-type formula, our approach leads to closed-form representations of the solutions in terms of special functions, not containing any derivative operators. We show normalizability and orthogonality of our solutions, as well as correct reduction of the problem to the harmonic oscillator model, if the parameter in the potential gets close to zero. (paper)

  12. SPECTRAL SMILE CORRECTION IN CRISM HYPERSPECTRAL IMAGES

    Science.gov (United States)

    Ceamanos, X.; Doute, S.

    2009-12-01

    The Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) is affected by a common artifact in "push-broom" sensors, the so-called "spectral smile". As a consequence, both central wavelength and spectral width of the spectral response vary along the across-track dimension, thus giving rise to a shifting and smoothing of spectra (see Fig. 1 (left)). In fact, both effects are greater for spectra on the edges, while they are minimum for data acquired by central detectors, the so-called "sweet spot". The prior artifacts become particularly critical for Martian observations which contain steep spectra such as CO2 ice-rich polar images. Fig. 1 (right) shows the horizontal brightness gradient which appears in every band corresponding to a steep portion of spectra. The correction of CRISM spectral smile is addressed using a two-step method which aims at modifying data sensibly in order to mimic the optimal CRISM response. First, all spectra, which are previously interpolated by cubic splines, are resampled to the "sweet spot" wavelengths in order to overcome the spectra shift. Secondly, the non-uniform spectral width is overcome by mimicking an increase of spectral resolution thanks to a spectral sharpening. In order to minimize noise, only bands particularly suffering from smile are selected. First, bands corresponding to the outliers of the Minimum Noise Transformation (MNF) eigenvector, which corresponds to the MNF band related to smile (MNF-smile), are selected. Then, a spectral neighborhood Θi, which takes into account the local spectral convexity or concavity, is defined for every selected band in order to maximize spectral shape preservation. The proposed sharpening technique takes into account both the instrument parameters and the observed spectra. First, every reflectance value belonging to a Θi is reevaluated by a sharpening which depends on a ratio of the spectral width of the current detector and the "sweet spot" one. Then, the optimal degree of

  13. Shedding Light on the Oxygen Reduction Reaction Mechanism in Ether-Based Electrolyte Solutions: A Study Using Operando UV-Vis Spectroscopy.

    Science.gov (United States)

    Hirshberg, Daniel; Sharon, Daniel; Afri, Michal; Lavi, Ronit; Frimer, Aryeh A; Metoki, Noa; Eliaz, Noam; Kwak, Won-Jin; Sun, Yang-Kook; Aurbach, Doron

    2018-04-04

    Using UV-vis spectroscopy in conjunction with various electrochemical techniques, we have developed a new effective operando methodology for investigating the oxygen reduction reactions (ORRs) and their mechanisms in nonaqueous solutions. We can follow the in situ formation and presence of superoxide moieties during ORR as a function of solvent, cations, anions, and additives in the solution. Thus, using operando UV-vis spectroscopy, we found evidence for the formation of superoxide radical anions during oxygen reduction in LiTFSI/diglyme electrolyte solutions. Nitro blue tetrazolium (NBT) was used to indicate the presence of superoxide moieties based on its unique spectral response. Indeed, the spectral response of NBT containing solutions undergoing ORR could provide a direct indication for the level of association of the Li cations with the electrolyte anions.

  14. Buckling feedback of the spectral calculations

    International Nuclear Information System (INIS)

    Jing Xingqing; Shan Wenzhi; Luo Jingyu

    1992-01-01

    This paper studies the problems about buckling feedback of spectral calculations in physical calculations of the reactor and presents a useful method by which the buckling feedback of spectral calculations is implemented. The effect of the buckling feedback in spectra and the broad group cross section, convergence of buckling feedback iteration and the effect of the spectral zones dividing are discussed in the calculations. This method has been used for the physical design of HTR-10 MW Test Module

  15. Spectral Slope as an Indicator of Pasture Quality

    Directory of Open Access Journals (Sweden)

    Rachel Lugassi

    2014-12-01

    Full Text Available In this study, we develop a spectral method for assessment of pasture quality based only on the spectral information obtained with a small number of wavelengths. First, differences in spectral behavior were identified across the near infrared–shortwave infrared spectral range that were indicative of changes in chemical properties. Then, slopes across different spectral ranges were calculated and correlated with the changes in crude protein (CP, neutral detergent fiber (NDF and metabolic energy concentration (MEC. Finally, partial least squares (PLS regression analysis was applied to identify the optimal spectral ranges for accurate assessment of CP, NDF and MEC. Six spectral domains and a set of slope criteria for real-time evaluation of pasture quality were suggested. The evaluation of three level categories (low, medium, high for these three parameters showed a success rate of: 73%–96% for CP, 72%–87% for NDF and 60%–85% for MEC. Moreover, only one spectral range, 1748–1764 nm, was needed to provide a good estimation of CP, NDF and MEC. Importantly, five of the six selected spectral regions were not affected by water absorbance. With some modifications, this rationale can be applied to further analyses of pasture quality from airborne sensors.

  16. Efficiency enhancement of ZnO nanostructure assisted Si solar cell based on fill factor enlargement and UV-blue spectral down-shifting

    International Nuclear Information System (INIS)

    Gholizadeh, A; Reyhani, A; Mortazavi, S Z; Parvin, P

    2017-01-01

    ZnO nanostructures (including nano-plates and nano-rods (NRs)) are grown in various temperatures and Ar/O 2 flow rates using thermal chemical vapor deposition, which affect the structure, nano-plate/NR population, and the quality of ZnO nanostructures. X-ray diffraction (XRD) attests that the peak intensity of the crystallographic plane (1 0 0) is correlated to nano-plate abundance. Moreover, optical properties elucidate that the population of nano-plates in samples strongly affect the band gap, binding energy of the exciton, and UV–visible (UV–vis) absorption and spectral luminescence emissions. In fact, the exciton binding energy reduces from ∼100 to 80 meV when the population of nano-plates increases in samples. Photovoltaic characteristics based on the drop-casting on Si solar cells reveals three dominant factors, namely, the equivalent series resistance, decreasing reflectance, and down-shifting, in order to scale up the absolute efficiency by 3%. As a consequence, the oxygen vacancies in ZnO nanostructures give rise to the down-shifting and increase of free-carriers, leading to a reduction in the equivalent series resistance and an enlargement of fill factor. To obtain a larger I sc , reduction of spectral reflectance is essential; however, the down-shifting process is shown to be dominant by lessening the surface electron-hole recombination rate over the UV–blue spectral range. (paper)

  17. Efficiency enhancement of ZnO nanostructure assisted Si solar cell based on fill factor enlargement and UV-blue spectral down-shifting

    Science.gov (United States)

    Gholizadeh, A.; Reyhani, A.; Parvin, P.; Mortazavi, S. Z.

    2017-05-01

    ZnO nanostructures (including nano-plates and nano-rods (NRs)) are grown in various temperatures and Ar/O2 flow rates using thermal chemical vapor deposition, which affect the structure, nano-plate/NR population, and the quality of ZnO nanostructures. X-ray diffraction (XRD) attests that the peak intensity of the crystallographic plane (1 0 0) is correlated to nano-plate abundance. Moreover, optical properties elucidate that the population of nano-plates in samples strongly affect the band gap, binding energy of the exciton, and UV-visible (UV-vis) absorption and spectral luminescence emissions. In fact, the exciton binding energy reduces from ~100 to 80 meV when the population of nano-plates increases in samples. Photovoltaic characteristics based on the drop-casting on Si solar cells reveals three dominant factors, namely, the equivalent series resistance, decreasing reflectance, and down-shifting, in order to scale up the absolute efficiency by 3%. As a consequence, the oxygen vacancies in ZnO nanostructures give rise to the down-shifting and increase of free-carriers, leading to a reduction in the equivalent series resistance and an enlargement of fill factor. To obtain a larger I sc, reduction of spectral reflectance is essential; however, the down-shifting process is shown to be dominant by lessening the surface electron-hole recombination rate over the UV-blue spectral range.

  18. Spectrally-Selective Photonic Structures for PV Applications

    Directory of Open Access Journals (Sweden)

    Benedikt Bläsi

    2010-01-01

    Full Text Available We review several examples of how spectrally-selective photonic structures may be used to improve solar cell systems. Firstly, we introduce different spectrally-selective structures that are based on interference effects. Examples shown include Rugate filter, edge filter and 3D photonic crystals such as artificial opals. In the second part, we discuss several examples of photovoltaic (PV concepts that utilize spectral selectivity such as fluorescence collectors, upconversion systems, spectrum splitting concepts and the intermediate reflector concept. The potential of spectrally selective filters in the context of solar cells is discussed.

  19. Multi-Configuration Matched Spectral Filter Core, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — OPTRA proposes an open-architecture spectral gas sensor based on compressive sensing concepts employed for both spatial and spectral domains. Our matched spectral...

  20. Adinkras, Dessins, Origami, and Supersymmetry Spectral Triples

    OpenAIRE

    Marcolli, Matilde; Zolman, Nick

    2016-01-01

    We investigate the spectral geometry and spectral action functionals associated to 1D Supersymmetry Algebras, using the classification of these superalgebras in terms of Adinkra graphs and the construction of associated dessin d'enfant and origami curves. The resulting spectral action functionals are computed in terms of the Selberg (super) trace formula.

  1. Partial Discharge Spectral Characterization in HF, VHF and UHF Bands Using Particle Swarm Optimization.

    Science.gov (United States)

    Robles, Guillermo; Fresno, José Manuel; Martínez-Tarifa, Juan Manuel; Ardila-Rey, Jorge Alfredo; Parrado-Hernández, Emilio

    2018-03-01

    The measurement of partial discharge (PD) signals in the radio frequency (RF) range has gained popularity among utilities and specialized monitoring companies in recent years. Unfortunately, in most of the occasions the data are hidden by noise and coupled interferences that hinder their interpretation and renders them useless especially in acquisition systems in the ultra high frequency (UHF) band where the signals of interest are weak. This paper is focused on a method that uses a selective spectral signal characterization to feature each signal, type of partial discharge or interferences/noise, with the power contained in the most representative frequency bands. The technique can be considered as a dimensionality reduction problem where all the energy information contained in the frequency components is condensed in a reduced number of UHF or high frequency (HF) and very high frequency (VHF) bands. In general, dimensionality reduction methods make the interpretation of results a difficult task because the inherent physical nature of the signal is lost in the process. The proposed selective spectral characterization is a preprocessing tool that facilitates further main processing. The starting point is a clustering of signals that could form the core of a PD monitoring system. Therefore, the dimensionality reduction technique should discover the best frequency bands to enhance the affinity between signals in the same cluster and the differences between signals in different clusters. This is done maximizing the minimum Mahalanobis distance between clusters using particle swarm optimization (PSO). The tool is tested with three sets of experimental signals to demonstrate its capabilities in separating noise and PDs with low signal-to-noise ratio and separating different types of partial discharges measured in the UHF and HF/VHF bands.

  2. The X-Shooter spectral library

    NARCIS (Netherlands)

    Chen, Y. P.; Trager, S. C.; Peletier, R. F.; Lançon, A.; Prugniel, Ph.; Koleva, M.

    2012-01-01

    We are building a new spectral library with the X-Shooter instrument on ESO's VLT: XSL, the X-Shooter Spectral Library. We present our progress in building XSL, which covers the wavelength range from the near-UV to the near-IR with a resolution of R˜10000. As of now we have collected spectra for

  3. A New Measurement of the Spectral Lag of Gamma-Ray Bursts and its Implications for Spectral Evolution Behaviors

    Energy Technology Data Exchange (ETDEWEB)

    Shao, Lang; Wang, Fu-Ri; Cheng, Ye-Hao; Zhang, Xi; Yu, Bang-Yao; Xi, Bao-Jia; Wang, Xue; Feng, Huan-Xue; Zhang, Meng, E-mail: lshao@hebtu.edu.cn [Department of Space Sciences and Astronomy, Hebei Normal University, Shijiazhuang 050024 (China); Zhang, Bin-Bin [Instituto de Astrofísica de Andalucá (IAA-CSIC), P.O. Box 03004, E-18080 Granada (Spain); Wu, Xue-Feng [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China); Xu, Dong [Key Laboratory of Space Astronomy and Technology, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)

    2017-08-01

    We carry out a systematical study of the spectral lag properties of 50 single-pulsed gamma-ray bursts (GRBs) detected by the Fermi Gamma-Ray Burst Monitor. By dividing the light curves into multiple consecutive energy channels, we provide a new measurement of the spectral lag that is independent of energy channel selections. We perform a detailed statistical study of our new measurements. We find two similar power-law energy dependencies of both the pulse arrival time and pulse width. Our new results on the power-law indices would favor the relativistic geometric effects for the origin of spectral lag. However, a complete theoretical framework that can fully account for the diverse energy dependencies of both arrival time and pulse width revealed in this work is still lacking. We also study the spectral evolution behaviors of the GRB pulses. We find that a GRB pulse with negligible spectral lag would usually have a shorter pulse duration and would appear to have a “hardness-intensity tracking” behavior, and a GRB pulse with a significant spectral lag would usually have a longer pulse duration and would appear to have a “hard-to-soft” behavior.

  4. Learning theory of distributed spectral algorithms

    International Nuclear Information System (INIS)

    Guo, Zheng-Chu; Lin, Shao-Bo; Zhou, Ding-Xuan

    2017-01-01

    Spectral algorithms have been widely used and studied in learning theory and inverse problems. This paper is concerned with distributed spectral algorithms, for handling big data, based on a divide-and-conquer approach. We present a learning theory for these distributed kernel-based learning algorithms in a regression framework including nice error bounds and optimal minimax learning rates achieved by means of a novel integral operator approach and a second order decomposition of inverse operators. Our quantitative estimates are given in terms of regularity of the regression function, effective dimension of the reproducing kernel Hilbert space, and qualification of the filter function of the spectral algorithm. They do not need any eigenfunction or noise conditions and are better than the existing results even for the classical family of spectral algorithms. (paper)

  5. The Open Spectral Database: an open platform for sharing and searching spectral data.

    Science.gov (United States)

    Chalk, Stuart J

    2016-01-01

    A number of websites make available spectral data for download (typically as JCAMP-DX text files) and one (ChemSpider) that also allows users to contribute spectral files. As a result, searching and retrieving such spectral data can be time consuming, and difficult to reuse if the data is compressed in the JCAMP-DX file. What is needed is a single resource that allows submission of JCAMP-DX files, export of the raw data in multiple formats, searching based on multiple chemical identifiers, and is open in terms of license and access. To address these issues a new online resource called the Open Spectral Database (OSDB) http://osdb.info/ has been developed and is now available. Built using open source tools, using open code (hosted on GitHub), providing open data, and open to community input about design and functionality, the OSDB is available for anyone to submit spectral data, making it searchable and available to the scientific community. This paper details the concept and coding, internal architecture, export formats, Representational State Transfer (REST) Application Programming Interface and options for submission of data. The OSDB website went live in November 2015. Concurrently, the GitHub repository was made available at https://github.com/stuchalk/OSDB/, and is open for collaborators to join the project, submit issues, and contribute code. The combination of a scripting environment (PHPStorm), a PHP Framework (CakePHP), a relational database (MySQL) and a code repository (GitHub) provides all the capabilities to easily develop REST based websites for ingestion, curation and exposure of open chemical data to the community at all levels. It is hoped this software stack (or equivalent ones in other scripting languages) will be leveraged to make more chemical data available for both humans and computers.

  6. Ensemble empirical mode decomposition based fluorescence spectral noise reduction for low concentration PAHs

    Science.gov (United States)

    Wang, Shu-tao; Yang, Xue-ying; Kong, De-ming; Wang, Yu-tian

    2017-11-01

    A new noise reduction method based on ensemble empirical mode decomposition (EEMD) is proposed to improve the detection effect for fluorescence spectra. Polycyclic aromatic hydrocarbons (PAHs) pollutants, as a kind of important current environmental pollution source, are highly oncogenic. Using the fluorescence spectroscopy method, the PAHs pollutants can be detected. However, instrument will produce noise in the experiment. Weak fluorescent signals can be affected by noise, so we propose a way to denoise and improve the detection effect. Firstly, we use fluorescence spectrometer to detect PAHs to obtain fluorescence spectra. Subsequently, noises are reduced by EEMD algorithm. Finally, the experiment results show the proposed method is feasible.

  7. SPECTRAL ANALYSIS OF EXCHANGE RATES

    Directory of Open Access Journals (Sweden)

    ALEŠA LOTRIČ DOLINAR

    2013-06-01

    Full Text Available Using spectral analysis is very common in technical areas but rather unusual in economics and finance, where ARIMA and GARCH modeling are much more in use. To show that spectral analysis can be useful in determining hidden periodic components for high-frequency finance data as well, we use the example of foreign exchange rates

  8. SPECTRAL SETS AND TILES IN CARTESIAN PRODUCTS OVER ...

    Indian Academy of Sciences (India)

    41

    Spectral set conjecture: A Borel set Ω ⊂ Rd of positive and finite. Lebesgue measure is a spectral set if and only if it ... Ω ⊂ G of positive and finite Haar measure is a spectral set if and only if it is a translational tile. ... Key words and phrases. p-adic number field, Cartesian product, tile, spectral set. This work was supported by ...

  9. Photovoltaic spectral responsivity measurements

    Energy Technology Data Exchange (ETDEWEB)

    Emery, K.; Dunlavy, D.; Field, H.; Moriarty, T. [National Renewable Energy Lab., Golden, CO (United States)

    1998-09-01

    This paper discusses the various elemental random and nonrandom error sources in typical spectral responsivity measurement systems. The authors focus specifically on the filter and grating monochrometer-based spectral responsivity measurement systems used by the Photovoltaic (PV) performance characterization team at NREL. A variety of subtle measurement errors can occur that arise from a finite photo-current response time, bandwidth of the monochromatic light, waveform of the monochromatic light, and spatial uniformity of the monochromatic and bias lights; the errors depend on the light source, PV technology, and measurement system. The quantum efficiency can be a function of he voltage bias, light bias level, and, for some structures, the spectral content of the bias light or location on the PV device. This paper compares the advantages and problems associated with semiconductor-detector-based calibrations and pyroelectric-detector-based calibrations. Different current-to-voltage conversion and ac photo-current detection strategies employed at NREL are compared and contrasted.

  10. Spectral dimension of quantum geometries

    International Nuclear Information System (INIS)

    Calcagni, Gianluca; Oriti, Daniele; Thürigen, Johannes

    2014-01-01

    The spectral dimension is an indicator of geometry and topology of spacetime and a tool to compare the description of quantum geometry in various approaches to quantum gravity. This is possible because it can be defined not only on smooth geometries but also on discrete (e.g., simplicial) ones. In this paper, we consider the spectral dimension of quantum states of spatial geometry defined on combinatorial complexes endowed with additional algebraic data: the kinematical quantum states of loop quantum gravity (LQG). Preliminarily, the effects of topology and discreteness of classical discrete geometries are studied in a systematic manner. We look for states reproducing the spectral dimension of a classical space in the appropriate regime. We also test the hypothesis that in LQG, as in other approaches, there is a scale dependence of the spectral dimension, which runs from the topological dimension at large scales to a smaller one at short distances. While our results do not give any strong support to this hypothesis, we can however pinpoint when the topological dimension is reproduced by LQG quantum states. Overall, by exploring the interplay of combinatorial, topological and geometrical effects, and by considering various kinds of quantum states such as coherent states and their superpositions, we find that the spectral dimension of discrete quantum geometries is more sensitive to the underlying combinatorial structures than to the details of the additional data associated with them. (paper)

  11. Extracting attosecond delays from spectrally overlapping interferograms

    Science.gov (United States)

    Jordan, Inga; Wörner, Hans Jakob

    2018-02-01

    Attosecond interferometry is becoming an increasingly popular technique for measuring the dynamics of photoionization in real time. Whereas early measurements focused on atomic systems with very simple photoelectron spectra, the technique is now being applied to more complex systems including isolated molecules and solids. The increase in complexity translates into an augmented spectral congestion, unavoidably resulting in spectral overlap in attosecond interferograms. Here, we discuss currently used methods for phase retrieval and introduce two new approaches for determining attosecond photoemission delays from spectrally overlapping photoelectron spectra. We show that the previously used technique, consisting in the spectral integration of the areas of interest, does in general not provide reliable results. Our methods resolve this problem, thereby opening the technique of attosecond interferometry to complex systems and fully exploiting its specific advantages in terms of spectral resolution compared to attosecond streaking.

  12. Abundance estimation of spectrally similar minerals

    CSIR Research Space (South Africa)

    Debba, Pravesh

    2009-07-01

    Full Text Available This paper evaluates a spectral unmixing method for estimating the partial abundance of spectrally similar minerals in complex mixtures. The method requires formulation of a linear function of individual spectra of individual minerals. The first...

  13. Adaption of an array spectroradiometer for total ozone column retrieval using direct solar irradiance measurements in the UV spectral range

    Science.gov (United States)

    Zuber, Ralf; Sperfeld, Peter; Riechelmann, Stefan; Nevas, Saulius; Sildoja, Meelis; Seckmeyer, Gunther

    2018-04-01

    A compact array spectroradiometer that enables precise and robust measurements of solar UV spectral direct irradiance is presented. We show that this instrument can retrieve total ozone column (TOC) accurately. The internal stray light, which is often the limiting factor for measurements in the UV spectral range and increases the uncertainty for TOC analysis, is physically reduced so that no other stray-light reduction methods, such as mathematical corrections, are necessary. The instrument has been extensively characterised at the Physikalisch-Technische Bundesanstalt (PTB) in Germany. During an international total ozone measurement intercomparison at the Izaña Atmospheric Observatory in Tenerife, the high-quality applicability of the instrument was verified with measurements of the direct solar irradiance and subsequent TOC evaluations based on the spectral data measured between 12 and 30 September 2016. The results showed deviations of the TOC of less than 1.5 % from most other instruments in most situations and not exceeding 3 % from established TOC measurement systems such as Dobson or Brewer.

  14. Salinity and spectral reflectance of soils

    Science.gov (United States)

    Szilagyi, A.; Baumgardner, M. F.

    1991-01-01

    The basic spectral response related to the salt content of soils in the visible and reflective IR wavelengths is analyzed in order to explore remote sensing applications for monitoring processes of the earth system. The bidirectional reflectance factor (BRF) was determined at 10 nm of increments over the 520-2320-nm spectral range. The effect of salts on reflectance was analyzed on the basis of 162 spectral measurements. MSS and TM bands were simulated within the measured spectral region. A strong relationship was found in variations of reflectance and soil characteristics pertaining to salinization and desalinization. Although the individual MSS bands had high R-squared values and 75-79 percent of soil/treatment combinations were separable, there was a large number of soil/treatment combinations not distinguished by any of the four highly correlated MSS bands under consideration.

  15. Implications of sensor design for coral reef detection: Upscaling ground hyperspectral imagery in spatial and spectral scales

    Science.gov (United States)

    Caras, Tamir; Hedley, John; Karnieli, Arnon

    2017-12-01

    Remote sensing offers a potential tool for large scale environmental surveying and monitoring. However, remote observations of coral reefs are difficult especially due to the spatial and spectral complexity of the target compared to sensor specifications as well as the environmental implications of the water medium above. The development of sensors is driven by technological advances and the desired products. Currently, spaceborne systems are technologically limited to a choice between high spectral resolution and high spatial resolution, but not both. The current study explores the dilemma of whether future sensor design for marine monitoring should prioritise on improving their spatial or spectral resolution. To address this question, a spatially and spectrally resampled ground-level hyperspectral image was used to test two classification elements: (1) how the tradeoff between spatial and spectral resolutions affects classification; and (2) how a noise reduction by majority filter might improve classification accuracy. The studied reef, in the Gulf of Aqaba (Eilat), Israel, is heterogeneous and complex so the local substrate patches are generally finer than currently available imagery. Therefore, the tested spatial resolution was broadly divided into four scale categories from five millimeters to one meter. Spectral resolution resampling aimed to mimic currently available and forthcoming spaceborne sensors such as (1) Environmental Mapping and Analysis Program (EnMAP) that is characterized by 25 bands of 6.5 nm width; (2) VENμS with 12 narrow bands; and (3) the WorldView series with broadband multispectral resolution. Results suggest that spatial resolution should generally be prioritized for coral reef classification because the finer spatial scale tested (pixel size mind, while the focus in this study was on the technologically limited spaceborne design, aerial sensors may presently provide an opportunity to implement the suggested setup.

  16. Digital staining for histopathology multispectral images by the combined application of spectral enhancement and spectral transformation.

    Science.gov (United States)

    Bautista, Pinky A; Yagi, Yukako

    2011-01-01

    In this paper we introduced a digital staining method for histopathology images captured with an n-band multispectral camera. The method consisted of two major processes: enhancement of the original spectral transmittance and the transformation of the enhanced transmittance to its target spectral configuration. Enhancement is accomplished by shifting the original transmittance with the scaled difference between the original transmittance and the transmittance estimated with m dominant principal component (PC) vectors;the m-PC vectors were determined from the transmittance samples of the background image. Transformation of the enhanced transmittance to the target spectral configuration was done using an nxn transformation matrix, which was derived by applying a least square method to the enhanced and target spectral training data samples of the different tissue components. Experimental results on the digital conversion of a hematoxylin and eosin (H&E) stained multispectral image to its Masson's trichrome stained (MT) equivalent shows the viability of the method.

  17. Semiconductor Laser Multi-Spectral Sensing and Imaging

    Directory of Open Access Journals (Sweden)

    Han Q. Le

    2010-01-01

    Full Text Available Multi-spectral laser imaging is a technique that can offer a combination of the laser capability of accurate spectral sensing with the desirable features of passive multispectral imaging. The technique can be used for detection, discrimination, and identification of objects by their spectral signature. This article describes and reviews the development and evaluation of semiconductor multi-spectral laser imaging systems. Although the method is certainly not specific to any laser technology, the use of semiconductor lasers is significant with respect to practicality and affordability. More relevantly, semiconductor lasers have their own characteristics; they offer excellent wavelength diversity but usually with modest power. Thus, system design and engineering issues are analyzed for approaches and trade-offs that can make the best use of semiconductor laser capabilities in multispectral imaging. A few systems were developed and the technique was tested and evaluated on a variety of natural and man-made objects. It was shown capable of high spectral resolution imaging which, unlike non-imaging point sensing, allows detecting and discriminating objects of interest even without a priori spectroscopic knowledge of the targets. Examples include material and chemical discrimination. It was also shown capable of dealing with the complexity of interpreting diffuse scattered spectral images and produced results that could otherwise be ambiguous with conventional imaging. Examples with glucose and spectral imaging of drug pills were discussed. Lastly, the technique was shown with conventional laser spectroscopy such as wavelength modulation spectroscopy to image a gas (CO. These results suggest the versatility and power of multi-spectral laser imaging, which can be practical with the use of semiconductor lasers.

  18. Semiconductor laser multi-spectral sensing and imaging.

    Science.gov (United States)

    Le, Han Q; Wang, Yang

    2010-01-01

    Multi-spectral laser imaging is a technique that can offer a combination of the laser capability of accurate spectral sensing with the desirable features of passive multispectral imaging. The technique can be used for detection, discrimination, and identification of objects by their spectral signature. This article describes and reviews the development and evaluation of semiconductor multi-spectral laser imaging systems. Although the method is certainly not specific to any laser technology, the use of semiconductor lasers is significant with respect to practicality and affordability. More relevantly, semiconductor lasers have their own characteristics; they offer excellent wavelength diversity but usually with modest power. Thus, system design and engineering issues are analyzed for approaches and trade-offs that can make the best use of semiconductor laser capabilities in multispectral imaging. A few systems were developed and the technique was tested and evaluated on a variety of natural and man-made objects. It was shown capable of high spectral resolution imaging which, unlike non-imaging point sensing, allows detecting and discriminating objects of interest even without a priori spectroscopic knowledge of the targets. Examples include material and chemical discrimination. It was also shown capable of dealing with the complexity of interpreting diffuse scattered spectral images and produced results that could otherwise be ambiguous with conventional imaging. Examples with glucose and spectral imaging of drug pills were discussed. Lastly, the technique was shown with conventional laser spectroscopy such as wavelength modulation spectroscopy to image a gas (CO). These results suggest the versatility and power of multi-spectral laser imaging, which can be practical with the use of semiconductor lasers.

  19. Vowel reduction in word-final position by early and late Spanish-English bilinguals.

    Directory of Open Access Journals (Sweden)

    Emily Byers

    Full Text Available Vowel reduction is a prominent feature of American English, as well as other stress-timed languages. As a phonological process, vowel reduction neutralizes multiple vowel quality contrasts in unstressed syllables. For bilinguals whose native language is not characterized by large spectral and durational differences between tonic and atonic vowels, systematically reducing unstressed vowels to the central vowel space can be problematic. Failure to maintain this pattern of stressed-unstressed syllables in American English is one key element that contributes to a "foreign accent" in second language speakers. Reduced vowels, or "schwas," have also been identified as particularly vulnerable to the co-articulatory effects of adjacent consonants. The current study examined the effects of adjacent sounds on the spectral and temporal qualities of schwa in word-final position. Three groups of English-speaking adults were tested: Miami-based monolingual English speakers, early Spanish-English bilinguals, and late Spanish-English bilinguals. Subjects performed a reading task to examine their schwa productions in fluent speech when schwas were preceded by consonants from various points of articulation. Results indicated that monolingual English and late Spanish-English bilingual groups produced targeted vowel qualities for schwa, whereas early Spanish-English bilinguals lacked homogeneity in their vowel productions. This extends prior claims that schwa is targetless for F2 position for native speakers to highly-proficient bilingual speakers. Though spectral qualities lacked homogeneity for early Spanish-English bilinguals, early bilinguals produced schwas with near native-like vowel duration. In contrast, late bilinguals produced schwas with significantly longer durations than English monolinguals or early Spanish-English bilinguals. Our results suggest that the temporal properties of a language are better integrated into second language phonologies than

  20. Classification of Error-Diffused Halftone Images Based on Spectral Regression Kernel Discriminant Analysis

    Directory of Open Access Journals (Sweden)

    Zhigao Zeng

    2016-01-01

    Full Text Available This paper proposes a novel algorithm to solve the challenging problem of classifying error-diffused halftone images. We firstly design the class feature matrices, after extracting the image patches according to their statistics characteristics, to classify the error-diffused halftone images. Then, the spectral regression kernel discriminant analysis is used for feature dimension reduction. The error-diffused halftone images are finally classified using an idea similar to the nearest centroids classifier. As demonstrated by the experimental results, our method is fast and can achieve a high classification accuracy rate with an added benefit of robustness in tackling noise.

  1. Spectral Imaging of Portolan Charts

    Science.gov (United States)

    France, Fenella G.; Wilson, Meghan A.; Ghez, Anita

    2018-05-01

    Spectral imaging of Portolan Charts, early nautical charts, provided extensive new information about their construction and creation. The origins of the portolan chart style have been a continual source of perplexity to numerous generations of cartographic historians. The spectral imaging system utilized incorporates a 50 megapixel mono-chrome camera with light emitting diode (LED) illumination panels that cover the range from 365 nm to 1050 nm to capture visible and non-visible information. There is little known about how portolan charts evolved, and what influenced their creation. These early nautical charts began as working navigational tools of medieval mariners, initially made in the 1300s in Italy, Portugal and Spain; however the origin and development of the portolan chart remained shrouded in mystery. Questions about these early navigational charts included whether colorants were commensurate with the time period and geographical location, and if different, did that give insight into trade routes, or possible later additions to the charts? For example; spectral data showed the red pigment on both the 1320 portolan chart and the 1565 Galapagos Islands matched vermillion, an opaque red pigment used since antiquity. The construction of these charts was also of great interest. Spectral imaging with a range of illumination modes revealed the presence of a "hidden circle" often referred to in relation to their construction. This paper will present in-depth analysis of how spectral imaging of the Portolans revealed similarities and differences, new hidden information and shed new light on construction and composition.

  2. Computer-assisted spectral design and synthesis

    Science.gov (United States)

    Vadakkumpadan, Fijoy; Wang, Qiqi; Sun, Yinlong

    2005-01-01

    In this paper, we propose a computer-assisted approach for spectral design and synthesis. This approach starts with some initial spectrum, modifies it interactively, evaluates the change, and decides the optimal spectrum. Given a requested change as function of wavelength, we model the change function using a Gaussian function. When there is the metameric constraint, from the Gaussian function of request change, we propose a method to generate the change function such that the result spectrum has the same color as the initial spectrum. We have tested the proposed method with different initial spectra and change functions, and implemented an interactive graphics environment for spectral design and synthesis. The proposed approach and graphics implementation for spectral design and synthesis can be helpful for a number of applications such as lighting of building interiors, textile coloration, and pigment development of automobile paints, and spectral computer graphics.

  3. Intermediate spectral theory and quantum dynamics

    CERN Document Server

    de Oliveira, Cesar R

    2008-01-01

    The spectral theory of linear operators plays a key role in the mathematical formulation of quantum theory. Furthermore, such a rigorous mathematical foundation leads to a more profound insight into the nature of quantum mechanics. This textbook provides a concise and comprehensible introduction to the spectral theory of (unbounded) self-adjoint operators and its application in quantum dynamics. The book places emphasis on the symbiotic relationship of these two domains by (1) presenting the basic mathematics of nonrelativistic quantum mechanics of one particle, i.e., developing the spectral theory of self-adjoint operators in infinite-dimensional Hilbert spaces from the beginning, and (2) giving an overview of many of the basic functional aspects of quantum theory, from its physical principles to the mathematical models. The book is intended for graduate (or advanced undergraduate) students and researchers interested in mathematical physics. It starts with linear operator theory, spectral questions and self-...

  4. Land Cover Classification Using Integrated Spectral, Temporal, and Spatial Features Derived from Remotely Sensed Images

    Directory of Open Access Journals (Sweden)

    Yongguang Zhai

    2018-03-01

    Full Text Available Obtaining accurate and timely land cover information is an important topic in many remote sensing applications. Using satellite image time series data should achieve high-accuracy land cover classification. However, most satellite image time-series classification methods do not fully exploit the available data for mining the effective features to identify different land cover types. Therefore, a classification method that can take full advantage of the rich information provided by time-series data to improve the accuracy of land cover classification is needed. In this paper, a novel method for time-series land cover classification using spectral, temporal, and spatial information at an annual scale was introduced. Based on all the available data from time-series remote sensing images, a refined nonlinear dimensionality reduction method was used to extract the spectral and temporal features, and a modified graph segmentation method was used to extract the spatial features. The proposed classification method was applied in three study areas with land cover complexity, including Illinois, South Dakota, and Texas. All the Landsat time series data in 2014 were used, and different study areas have different amounts of invalid data. A series of comparative experiments were conducted on the annual time-series images using training data generated from Cropland Data Layer. The results demonstrated higher overall and per-class classification accuracies and kappa index values using the proposed spectral-temporal-spatial method compared to spectral-temporal classification methods. We also discuss the implications of this study and possibilities for future applications and developments of the method.

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

    International Nuclear Information System (INIS)

    Gran, Jarle

    2005-01-01

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

  6. Low Delay Noise Reduction and Dereverberation for Hearing Aids

    Directory of Open Access Journals (Sweden)

    Heinrich W. Löllmann

    2009-01-01

    Full Text Available A new system for single-channel speech enhancement is proposed which achieves a joint suppression of late reverberant speech and background noise with a low signal delay and low computational complexity. It is based on a generalized spectral subtraction rule which depends on the variances of the late reverberant speech and background noise. The calculation of the spectral variances of the late reverberant speech requires an estimate of the reverberation time (RT which is accomplished by a maximum likelihood (ML approach. The enhancement with this blind RT estimation achieves almost the same speech quality as by using the actual RT. In comparison to commonly used post-filters in hearing aids which only perform a noise reduction, a significantly better objective and subjective speech quality is achieved. The proposed system performs time-domain filtering with coefficients adapted in the non-uniform (Bark-scaled frequency-domain. This allows to achieve a high speech quality with low signal delay which is important for speech enhancement in hearing aids or related applications such as hands-free communication systems.

  7. Emissivity compensated spectral pyrometry—algorithm and sensitivity analysis

    International Nuclear Information System (INIS)

    Hagqvist, Petter; Sikström, Fredrik; Christiansson, Anna-Karin; Lennartson, Bengt

    2014-01-01

    In order to solve the problem of non-contact temperature measurements on an object with varying emissivity, a new method is herein described and evaluated. The method uses spectral radiance measurements and converts them to temperature readings. It proves to be resilient towards changes in spectral emissivity and tolerates noisy spectral measurements. It is based on an assumption of smooth changes in emissivity and uses historical values of spectral emissivity and temperature for estimating current spectral emissivity. The algorithm, its constituent steps and accompanying parameters are described and discussed. A thorough sensitivity analysis of the method is carried out through simulations. No rigorous instrument calibration is needed for the presented method and it is therefore industrially tractable. (paper)

  8. Effects of spectral smearing on performance of the spectral ripple and spectro-temporal ripple tests.

    Science.gov (United States)

    Narne, Vijaya Kumar; Sharma, Mridula; Van Dun, Bram; Bansal, Shalini; Prabhu, Latika; Moore, Brian C J

    2016-12-01

    The main aim of this study was to use spectral smearing to evaluate the efficacy of a spectral ripple test (SRt) using stationary sounds and a recent variant with gliding ripples called the spectro-temporal ripple test (STRt) in measuring reduced spectral resolution. In experiment 1 the highest detectable ripple density was measured using four amounts of spectral smearing (unsmeared, mild, moderate, and severe). The thresholds worsened with increasing smearing and were similar for the SRt and the STRt across the three conditions with smearing. For unsmeared stimuli, thresholds were significantly higher (better) for the STRt than for the SRt. An amplitude fluctuation at the outputs of simulated (gammatone) auditory filters centered above 6400 Hz was identified as providing a potential detection cue for the STRt stimuli. Experiment 2 used notched noise with energy below and above the passband of the SRt and STRt stimuli to reduce confounding cues in the STRt. Thresholds were almost identical for the STRt and SRt for both unsmeared and smeared stimuli, indicating that the confounding cue for the STRt was eliminated by the notched noise. Thresholds obtained with notched noise present could be predicted reasonably accurately using an excitation-pattern model.

  9. Spectral Compressive Sensing with Polar Interpolation

    DEFF Research Database (Denmark)

    Fyhn, Karsten; Dadkhahi, Hamid; F. Duarte, Marco

    2013-01-01

    . In this paper, we introduce a greedy recovery algorithm that leverages a band-exclusion function and a polar interpolation function to address these two issues in spectral compressive sensing. Our algorithm is geared towards line spectral estimation from compressive measurements and outperforms most existing...

  10. USGS Digital Spectral Library splib06a

    Science.gov (United States)

    Clark, Roger N.; Swayze, Gregg A.; Wise, Richard A.; Livo, K. Eric; Hoefen, Todd M.; Kokaly, Raymond F.; Sutley, Stephen J.

    2007-01-01

    Introduction We have assembled a digital reflectance spectral library that covers the wavelength range from the ultraviolet to far infrared along with sample documentation. The library includes samples of minerals, rocks, soils, physically constructed as well as mathematically computed mixtures, plants, vegetation communities, microorganisms, and man-made materials. The samples and spectra collected were assembled for the purpose of using spectral features for the remote detection of these and similar materials. Analysis of spectroscopic data from laboratory, aircraft, and spacecraft instrumentation requires a knowledge base. The spectral library discussed here forms a knowledge base for the spectroscopy of minerals and related materials of importance to a variety of research programs being conducted at the U.S. Geological Survey. Much of this library grew out of the need for spectra to support imaging spectroscopy studies of the Earth and planets. Imaging spectrometers, such as the National Aeronautics and Space Administration (NASA) Airborne Visible/Infra Red Imaging Spectrometer (AVIRIS) or the NASA Cassini Visual and Infrared Mapping Spectrometer (VIMS) which is currently orbiting Saturn, have narrow bandwidths in many contiguous spectral channels that permit accurate definition of absorption features in spectra from a variety of materials. Identification of materials from such data requires a comprehensive spectral library of minerals, vegetation, man-made materials, and other subjects in the scene. Our research involves the use of the spectral library to identify the components in a spectrum of an unknown. Therefore, the quality of the library must be very good. However, the quality required in a spectral library to successfully perform an investigation depends on the scientific questions to be answered and the type of algorithms to be used. For example, to map a mineral using imaging spectroscopy and the mapping algorithm of Clark and others (1990a, 2003b

  11. Maximum spectral demands in the near-fault region

    Science.gov (United States)

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

    2008-01-01

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

  12. Spectral features in the cosmic ray fluxes

    Science.gov (United States)

    Lipari, Paolo

    2018-01-01

    The cosmic ray energy distributions contain spectral features, that is narrow energy regions where the slope of the spectrum changes rapidly. The identification and study of these features is of great importance to understand the astrophysical mechanisms of acceleration and propagation that form the spectra. In first approximation a spectral feature is often described as a discontinuous change in slope, however very valuable information is also contained in its width, that is the length of the energy interval where the change in spectral index develops. In this work we discuss the best way to define and parameterize the width a spectral feature, and for illustration discuss some of the most prominent known structures.

  13. Spectral State Evolution of 4U 1820-30: the Stability of the Spectral Index of Comptonization Tail

    Science.gov (United States)

    Titarchuk, Lev G.; Seifina, Elena; Frontera, Filippo

    2013-01-01

    We analyze the X-ray spectra and their timing properties of the compact Xray binary 4U 1820-30. We establish spectral transitions in this source seen with BeppoSAX and the Rossi X-ray Timing Explorer (RXTE). During the RXTE observations (1996 - 2009), the source were approximately approximately 75% of its time in the soft state making the lower banana and upper banana transitions combined with long-term low-high state transitions. We reveal that all of the X-ray spectra of 4U 1820-30 are fit by a composition of a thermal (blackbody) component, a Comptonization component (COMPTB) and a Gaussian-line component. Thus using this spectral analysis we find that the photon power-law index Gamma of the Comptonization component is almost unchangeable (Gamma approximately 2) while the electron temperature kTe changes from 2.9 to 21 keV during these spectral events. We also establish that for these spectral events the normalization of COMPTB component (which is proportional to mass accretion rate ?M) increases by factor 8 when kTe decreases from 21 keV to 2.9 keV. Before this index stability effect was also found analyzing X-ray data for Z-source GX 340+0 and for atolls, 4U 1728-34, GX 3+1. Thus, we can suggest that this spectral stability property is a spectral signature of an accreting neutron star source. On the other hand in a black hole binary G monotonically increases with ?Mand ultimately its value saturates at large ?M.

  14. Total spectral distributions from Hawking radiation

    Energy Technology Data Exchange (ETDEWEB)

    Broda, Boguslaw [University of Lodz, Department of Theoretical Physics, Faculty of Physics and Applied Informatics, Lodz (Poland)

    2017-11-15

    Taking into account the time dependence of the Hawking temperature and finite evaporation time of the black hole, the total spectral distributions of the radiant energy and of the number of particles have been explicitly calculated and compared to their temporary (initial) blackbody counterparts (spectral exitances). (orig.)

  15. Spectral zone selection methodology for pebble bed reactors

    International Nuclear Information System (INIS)

    Mphahlele, Ramatsemela; Ougouag, Abderrafi M.; Ivanov, Kostadin N.; Gougar, Hans D.

    2011-01-01

    A methodology is developed for determining boundaries of spectral zones for pebble bed reactors. A spectral zone is defined as a region made up of a number of nodes whose characteristics are collectively similar and that are assigned the same few-group diffusion constants. The spectral zones are selected in such a manner that the difference (error) between the reference transport solution and the diffusion code solution takes a minimum value. This is achieved by choosing spectral zones through optimally minimizing this error. The objective function for the optimization algorithm is the total reaction rate error, which is defined as the sum of the leakage, absorption and fission reaction rates errors in each zone. The selection of these spectral zones is such that the core calculation results based on diffusion theory are within an acceptable tolerance as compared to a proper transport reference solution. Through this work, a consistent approach for identifying spectral zones that yield more accurate diffusion results is introduced.

  16. Spectral analysis and filter theory in applied geophysics

    CERN Document Server

    Buttkus, Burkhard

    2000-01-01

    This book is intended to be an introduction to the fundamentals and methods of spectral analysis and filter theory and their appli­ cations in geophysics. The principles and theoretical basis of the various methods are described, their efficiency and effectiveness eval­ uated, and instructions provided for their practical application. Be­ sides the conventional methods, newer methods arediscussed, such as the spectral analysis ofrandom processes by fitting models to the ob­ served data, maximum-entropy spectral analysis and maximum-like­ lihood spectral analysis, the Wiener and Kalman filtering methods, homomorphic deconvolution, and adaptive methods for nonstation­ ary processes. Multidimensional spectral analysis and filtering, as well as multichannel filters, are given extensive treatment. The book provides a survey of the state-of-the-art of spectral analysis and fil­ ter theory. The importance and possibilities ofspectral analysis and filter theory in geophysics for data acquisition, processing an...

  17. Comparisons of spectral characteristics of wind noise between omnidirectional and directional microphones.

    Science.gov (United States)

    Chung, King

    2012-06-01

    Wind noise reduction is a topic of ongoing research and development for hearing aids and cochlear implants. The purposes of this study were to examine spectral characteristics of wind noise generated by directional (DIR) and omnidirectional (OMNI) microphones on different styles of hearing aids and to derive wind noise reduction strategies. Three digital hearing aids (BTE, ITE, and ITC) were fitted to Knowles Electronic Manikin for Acoustic Research. They were programmed to have linear amplification and matching frequency responses between the DIR and OMNI modes. Flow noise recordings were made from 0° to 360° azimuths at flow velocities of 4.5, 9.0, and 13.5 m/s in a quiet wind tunnel. Noise levels were analyzed in one-third octave bands from 100 to 8000 Hz. Comparison of wind noise revealed that DIR generally produced higher noise levels than OMNI for all hearing aids, but it could result in lower levels than OMNI at some frequencies and head angles. Wind noise reduction algorithms can be designed to detect noise levels of DIR and OMNI outputs in each frequency channel, remove the constraint to switch to OMNI in low-frequency channel(s) only, and adopt the microphone mode with lower noise levels to take advantage of the microphone differences.

  18. Diagnostic spectral characteristics of damouritization in granite type uranium deposit

    International Nuclear Information System (INIS)

    He Jianguo; Mao Yuxian; Li Jianzhong; Wang Changliang; Feng Mingyue; Rong Jiashu; Zhu Minqiang; Rao Minghui

    2008-01-01

    Spectral characteristics of different alteration type in uranium deposit are the prerequisite of selecting remote sensing spectral bands for uranium reconnaissance and exploration. It is also a basis for mapping alteration zone using imaging spectral data. Taking the No. 201 uranium deposit as example, the paper is focused on the spectral characteristics researching of damouritization in granite type uranium deposite. Through extracting diagnostic spectral feature of damourite and analyzing the reason causing absorption valley, it was found that spectral characteristics of damouritization in Chinese uranium deposit is different from that of illite in the spectral library published abroad. (authors)

  19. Diagnostic spectral characteristics of damouritization in granite type uranium deposit

    Energy Technology Data Exchange (ETDEWEB)

    Jianguo, He; Yuxian, Mao; Jianzhong, Li; Changliang, Wang; Mingyue, Feng; Jiashu, Rong [Beijing Research Inst. of Uranium Geology, Beijing (China); Minqiang, Zhu; Minghui, Rao [East China Univ. of Technology, Fuzhou (China)

    2008-07-15

    Spectral characteristics of different alteration type in uranium deposit are the prerequisite of selecting remote sensing spectral bands for uranium reconnaissance and exploration. It is also a basis for mapping alteration zone using imaging spectral data. Taking the No. 201 uranium deposit as example, the paper is focused on the spectral characteristics researching of damouritization in granite type uranium deposite. Through extracting diagnostic spectral feature of damourite and analyzing the reason causing absorption valley, it was found that spectral characteristics of damouritization in Chinese uranium deposit is different from that of illite in the spectral library published abroad. (authors)

  20. FSD: Frequency Space Differential measurement of CMB spectral distortions

    Science.gov (United States)

    Mukherjee, Suvodip; Silk, Joseph; Wandelt, Benjamin D.

    2018-04-01

    Although the Cosmic Microwave Background agrees with a perfect blackbody spectrum within the current experimental limits, it is expected to exhibit certain spectral distortions with known spectral properties. We propose a new method, Frequency Space Differential (FSD) to measure the spectral distortions in the CMB spectrum by using the inter-frequency differences of the brightness temperature. The difference between the observed CMB temperature at different frequencies must agree with the frequency derivative of the blackbody spectrum, in the absence of any distortion. However, in the presence of spectral distortions, the measured inter-frequency differences would also exhibit deviations from blackbody which can be modeled for known sources of spectral distortions like y & μ. Our technique uses FSD information for the CMB blackbody, y, μ or any other sources of spectral distortions to model the observed signal. Successful application of this method in future CMB missions can provide an alternative method to extract spectral distortion signals and can potentially make it feasible to measure spectral distortions without an internal blackbody calibrator.

  1. SPECTRAL TYPING OF LATE-TYPE STELLAR COMPANIONS TO YOUNG STARS FROM LOW-DISPERSION NEAR-INFRARED INTEGRAL FIELD UNIT DATA

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, Lewis C.; Beichman, Charles A.; Burruss, Rick; Ligon, E. Robert; Lockhart, Thomas G.; Roberts, Jennifer E.; Shao, Michael [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Rice, Emily L.; Brenner, Douglas; Oppenheimer, Ben R. [American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024 (United States); Crepp, Justin R.; Dekany, Richard G.; Hillenbrand, Lynne A.; Hinkley, Sasha [California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 (United States); King, David; Parry, Ian R. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 OHA (United Kingdom); Metchev, Stanimir [Department of Physics and Astronomy, State University of New York, Stony Brook, NY 11794-3800 (United States); Pueyo, Laurent; Sivaramakrishnan, Anand; Soummer, Remi, E-mail: lewis.c.roberts@jpl.nasa.gov [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); and others

    2012-07-15

    We used the Project 1640 near-infrared coronagraph and integral field spectrograph to observe 19 young solar-type stars. Five of these stars are known binary stars and we detected the late-type secondaries and were able to measure their JH spectra with a resolution of R {approx} 30. The reduced, extracted, and calibrated spectra were compared to template spectra from the IRTF spectral library. With this comparison, we test the accuracy and consistency of spectral-type determination with the low-resolution near-infrared spectra from P1640. Additionally, we determine effective temperature and surface gravity of the companions by fitting synthetic spectra calculated with the PHOENIX model atmosphere code. We also present several new epochs of astrometry of each of the systems. Together, these data increase our knowledge and understanding of the stellar make up of these systems. In addition to the astronomical results, the analysis presented helps validate the Project 1640 data reduction and spectral extraction processes and the utility of low-resolution, near-infrared spectra for characterizing late-type companions in multiple systems.

  2. 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

  3. Enzyme activity measurement via spectral evolution profiling and PARAFAC

    DEFF Research Database (Denmark)

    Baum, Andreas; Meyer, Anne S.; Garcia, Javier Lopez

    2013-01-01

    The recent advances in multi-way analysis provide new solutions to traditional enzyme activity assessment. In the present study enzyme activity has been determined by monitoring spectral changes of substrates and products in real time. The method relies on measurement of distinct spectral...... fingerprints of the reaction mixture at specific time points during the course of the whole enzyme catalyzed reaction and employs multi-way analysis to detect the spectral changes. The methodology is demonstrated by spectral evolution profiling of Fourier Transform Infrared (FTIR) spectral fingerprints using...

  4. Thin film optical coatings for the ultraviolet spectral region

    Science.gov (United States)

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

    2017-11-01

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

  5. Spectral decomposition of tent maps using symmetry considerations

    International Nuclear Information System (INIS)

    Ordonez, G.E.; Driebe, D.J.

    1996-01-01

    The spectral decompostion of the Frobenius-Perron operator of maps composed of many tents is determined from symmetry considerations. The eigenstates involve Euler as well as Bernoulli polynomials. The authors have introduced some new techniques, based on symmetry considerations, enabling the construction of spectral decompositions in a much simpler way than previous construction algorithms, Here we utilize these techniques to construct the spectral decomposition for one- dimensional maps of the unit interval composed of many tents. The construction uses the knowledge of the spectral decomposition of the r-adic map, which involves Bernoulli polynomials and their duals. It will be seen that the spectral decomposition of the tent maps involves both Bernoulli polynomials and Euler polynomials along with the appropriate dual states

  6. A spectral/B-spline method for the Navier-Stokes equations in unbounded domains

    CERN Document Server

    Dufresne, L

    2003-01-01

    The numerical method presented in this paper aims at solving the incompressible Navier-Stokes equations in unbounded domains. The problem is formulated in cylindrical coordinates and the method is based on a Galerkin approximation scheme that makes use of vector expansions that exactly satisfy the continuity constraint. More specifically, the divergence-free basis vector functions are constructed with Fourier expansions in the theta and z directions while mapped B-splines are used in the semi-infinite radial direction. Special care has been taken to account for the particular analytical behaviors at both end points r=0 and r-> infinity. A modal reduction algorithm has also been implemented in the azimuthal direction, allowing for a relaxation of the CFL constraint on the timestep size and a possibly significant reduction of the number of DOF. The time marching is carried out using a mixed quasi-third order scheme. Besides the advantages of a divergence-free formulation and a quasi-spectral convergence, the lo...

  7. Multi-spectral confocal microendoscope for in-vivo imaging

    Science.gov (United States)

    Rouse, Andrew Robert

    The concept of in-vivo multi-spectral confocal microscopy is introduced. A slit-scanning multi-spectral confocal microendoscope (MCME) was built to demonstrate the technique. The MCME employs a flexible fiber-optic catheter coupled to a custom built slit-scan confocal microscope fitted with a custom built imaging spectrometer. The catheter consists of a fiber-optic imaging bundle linked to a miniature objective and focus assembly. The design and performance of the miniature objective and focus assembly are discussed. The 3mm diameter catheter may be used on its own or routed though the instrument channel of a commercial endoscope. The confocal nature of the system provides optical sectioning with 3mum lateral resolution and 30mum axial resolution. The prism based multi-spectral detection assembly is typically configured to collect 30 spectral samples over the visible chromatic range. The spectral sampling rate varies from 4nm/pixel at 490nm to 8nm/pixel at 660nm and the minimum resolvable wavelength difference varies from 7nm to 18nm over the same spectral range. Each of these characteristics are primarily dictated by the dispersive power of the prism. The MCME is designed to examine cellular structures during optical biopsy and to exploit the diagnostic information contained within the spectral domain. The primary applications for the system include diagnosis of disease in the gastro-intestinal tract and female reproductive system. Recent data from the grayscale imaging mode are presented. Preliminary multi-spectral results from phantoms, cell cultures, and excised human tissue are presented to demonstrate the potential of in-vivo multi-spectral imaging.

  8. Spectral backward radiation profile

    International Nuclear Information System (INIS)

    Kwon, Sung Duck; Lee, Keun Hyun; Kim, Bo Ra; Yoon, Suk Soo

    2004-01-01

    Ultrasonic backward radiation profile is frequency-dependent when incident region has deptional gradient of acoustical properties or multi-layers. Until now, we have measured the profiles of principal frequencies of used transducers so that it was not easy to understand the change of the frequency component and spectrum of backward radiation from the profile. We tried to measure the spectral backward radiation profiles using DFP(digital filer package) Lecroy DSO. The very big changes in the shape and pattern of spectral backward radiation profiles leads to the conclusion that this new try could be very effective tool to evaluate frequency dependent surface area.

  9. Rayleigh imaging in spectral mammography

    Science.gov (United States)

    Berggren, Karl; Danielsson, Mats; Fredenberg, Erik

    2016-03-01

    Spectral imaging is the acquisition of multiple images of an object at different energy spectra. In mammography, dual-energy imaging (spectral imaging with two energy levels) has been investigated for several applications, in particular material decomposition, which allows for quantitative analysis of breast composition and quantitative contrast-enhanced imaging. Material decomposition with dual-energy imaging is based on the assumption that there are two dominant photon interaction effects that determine linear attenuation: the photoelectric effect and Compton scattering. This assumption limits the number of basis materials, i.e. the number of materials that are possible to differentiate between, to two. However, Rayleigh scattering may account for more than 10% of the linear attenuation in the mammography energy range. In this work, we show that a modified version of a scanning multi-slit spectral photon-counting mammography system is able to acquire three images at different spectra and can be used for triple-energy imaging. We further show that triple-energy imaging in combination with the efficient scatter rejection of the system enables measurement of Rayleigh scattering, which adds an additional energy dependency to the linear attenuation and enables material decomposition with three basis materials. Three available basis materials have the potential to improve virtually all applications of spectral imaging.

  10. Impact of reduction of tinnitus intensity on patients' quality of life.

    Science.gov (United States)

    Drexler, Daniel; López-Paullier, Matías; Rodio, Silvana; González, Manuela; Geisinger, Darío; Pedemonte, Marisa

    2016-01-01

    Assess the impact of a reduction of tinnitus intensity achieved through sound stimulation during sleep on the improvement in the patients' quality of life. Acoustic stimuli consisted of a highly customized sound that reproduced the spectral and intensity characteristics of the tinnitus in each patient. This stimulus was uploaded into a portable electronic device and delivered through customized ear buds during sleep, every night for three months. Twelve patients with subjective idiopathic chronic tinnitus were studied. Results were assessed through: (1) the measurement in dB SPL of tinnitus intensity reduction over time; (2) the results of three psychometric tests: Tinnitus handicap inventory (THI), Tinnitus reaction questionnaire (TRQ), Tinnitus functional index (TFI); and (3) a Visual analog scale (VAS) for tinnitus annoyance. After three months of treatment, we observed an average decrease in tinnitus intensity of 14.1 dB SPL (p < 0.001), implying a 62% reduction of the perceived sound. This improvement was followed by a statistically significant decrease of TRQ (78%), THI (65%), and TFI (77%). These results suggested that the intensity reduction achieved through the protocol used in this study had a direct impact on the improvement in the patients' quality of life.

  11. Spectral functions from hadronic τ decays

    International Nuclear Information System (INIS)

    Davier, Michel

    2002-01-01

    Hadronic decays of the τ lepton provide a clean environment to study hadron dynamics in an energy regime dominated by romances, with the interesting information captured in the spectral functions. Recent results on exclusive channels are reviewed. Inclusive spectral functions are the basis for QCD analyses, delivering an accurate determination of the strong coupling constant and quantitative information on nonpertubative contributions. the τ vector spectral functions for the 2π and 4π final states are used together with e p+ e p- data in order to compute vacuum polarization integrals occurring in the calculations of the anomalous magnetic moment of the muon and the running of the electromagnetic coupling

  12. Adiabatic theorem and spectral concentration

    International Nuclear Information System (INIS)

    Nenciu, G.

    1981-01-01

    The spectral concentration of arbitrary order, for the Stark effect is proved to exist for a large class of Hamiltonians appearing in nonrelativistic and relativistic quantum mechanics. The results are consequences of an abstract theorem about the spectral concentration for self-ad oint operators. A general form of the adiabatic theorem of quantum mechanics, generalizing an earlier result of the author as well as some results of Lenard, is also proved [ru

  13. Method for estimating effects of unknown correlations in spectral irradiance data on uncertainties of spectrally integrated colorimetric quantities

    Science.gov (United States)

    Kärhä, Petri; Vaskuri, Anna; Mäntynen, Henrik; Mikkonen, Nikke; Ikonen, Erkki

    2017-08-01

    Spectral irradiance data are often used to calculate colorimetric properties, such as color coordinates and color temperatures of light sources by integration. The spectral data may contain unknown correlations that should be accounted for in the uncertainty estimation. We propose a new method for estimating uncertainties in such cases. The method goes through all possible scenarios of deviations using Monte Carlo analysis. Varying spectral error functions are produced by combining spectral base functions, and the distorted spectra are used to calculate the colorimetric quantities. Standard deviations of the colorimetric quantities at different scenarios give uncertainties assuming no correlations, uncertainties assuming full correlation, and uncertainties for an unfavorable case of unknown correlations, which turn out to be a significant source of uncertainty. With 1% standard uncertainty in spectral irradiance, the expanded uncertainty of the correlated color temperature of a source corresponding to the CIE Standard Illuminant A may reach as high as 37.2 K in unfavorable conditions, when calculations assuming full correlation give zero uncertainty, and calculations assuming no correlations yield the expanded uncertainties of 5.6 K and 12.1 K, with wavelength steps of 1 nm and 5 nm used in spectral integrations, respectively. We also show that there is an absolute limit of 60.2 K in the error of the correlated color temperature for Standard Illuminant A when assuming 1% standard uncertainty in the spectral irradiance. A comparison of our uncorrelated uncertainties with those obtained using analytical methods by other research groups shows good agreement. We re-estimated the uncertainties for the colorimetric properties of our 1 kW photometric standard lamps using the new method. The revised uncertainty of color temperature is a factor of 2.5 higher than the uncertainty assuming no correlations.

  14. Spectral concentration in the nonrelativistic limit

    International Nuclear Information System (INIS)

    Gesztesy, F.; Grosse, H.; Thaller, B.

    1982-01-01

    First order relativistic corrections to the Schroedinger operator according to Foldy and Wouthuysen are rigorously discussed in the framework of singular perturbation theory. For Coulomb plus short-range interactions we investigate the corresponding spectral properties and prove spectral concentration and existence of first order pseudoeigenvalues in the nonrelativistic limit. (Author)

  15. Spectral Methods in Numerical Plasma Simulation

    DEFF Research Database (Denmark)

    Coutsias, E.A.; Hansen, F.R.; Huld, T.

    1989-01-01

    An introduction is given to the use of spectral methods in numerical plasma simulation. As examples of the use of spectral methods, solutions to the two-dimensional Euler equations in both a simple, doubly periodic region, and on an annulus will be shown. In the first case, the solution is expanded...

  16. THE SPECTRAL INDEX PROPERTIES OF FERMI BLAZARS

    Energy Technology Data Exchange (ETDEWEB)

    Fan, J. H.; Yang, J. H.; Yuan, Y. H.; Wang, J.; Gao, Y., E-mail: jhfan_cn@yahoo.com.cn [Center for Astrophysics, Guangzhou University, Guangzhou 510006 (China)

    2012-12-20

    In this paper, a sample of 451 blazars (193 flat spectrum radio quasars (FSRQs), 258 BL Lacertae objects) with corresponding X-ray and Fermi {gamma}-ray data is compiled to investigate the correlation both between the X-ray spectral index and the {gamma}-ray spectral index and between the spectral index and the luminosity, and to compare the spectral indexes {alpha}{sub X}, {alpha}{sub {gamma}}, {alpha}{sub X{gamma}}, and {alpha}{sub {gamma}X{gamma}} for different subclasses. We also investigated the correlation between the X-ray and the {gamma}-ray luminosity. The following results have been obtained. Our analysis indicates that an anti-correlation exists between the X-ray and the {gamma}-ray spectral indexes for the whole sample. However, when we considered the subclasses of blazars (FSRQs, the low-peaked BL Lacertae objects (LBLs) and the high-peaked BL Lacertae objects (HBLs)) separately, there is not a clear relationship for each subclass. Based on the Fermi-detected sources, we can say that the HBLs are different from FSRQs, while the LBLs are similar to FSRQs.

  17. Rectangular spectral collocation

    KAUST Repository

    Driscoll, Tobin A.; Hale, Nicholas

    2015-01-01

    Boundary conditions in spectral collocation methods are typically imposed by removing some rows of the discretized differential operator and replacing them with others that enforce the required conditions at the boundary. A new approach based upon

  18. A Bayesian approach to spectral quantitative photoacoustic tomography

    International Nuclear Information System (INIS)

    Pulkkinen, A; Kaipio, J P; Tarvainen, T; Cox, B T; Arridge, S R

    2014-01-01

    A Bayesian approach to the optical reconstruction problem associated with spectral quantitative photoacoustic tomography is presented. The approach is derived for commonly used spectral tissue models of optical absorption and scattering: the absorption is described as a weighted sum of absorption spectra of known chromophores (spatially dependent chromophore concentrations), while the scattering is described using Mie scattering theory, with the proportionality constant and spectral power law parameter both spatially-dependent. It is validated using two-dimensional test problems composed of three biologically relevant chromophores: fat, oxygenated blood and deoxygenated blood. Using this approach it is possible to estimate the Grüneisen parameter, the absolute chromophore concentrations, and the Mie scattering parameters associated with spectral photoacoustic tomography problems. In addition, the direct estimation of the spectral parameters is compared to estimates obtained by fitting the spectral parameters to estimates of absorption, scattering and Grüneisen parameter at the investigated wavelengths. It is shown with numerical examples that the direct estimation results in better accuracy of the estimated parameters. (papers)

  19. Solar Spectral Irradiance Changes During Cycle 24

    Science.gov (United States)

    Marchenko, Sergey; Deland, Matthew

    2014-01-01

    We use solar spectra obtained by the Ozone Monitoring Instrument (OMI) on board the Aura satellite to detect and follow long-term (years) and short-term (weeks) changes in the solar spectral irradiance (SSI) in the 265-500 nm spectral range. During solar Cycle 24, in the relatively line-free regions the SSI changed by approximately 0.6% +/- 0.2% around 265 nm. These changes gradually diminish to 0.15% +/- 0.20% at 500 nm. All strong spectral lines and blends, with the notable exception of the upper Balmer lines, vary in unison with the solar "continuum." Besides the lines with strong chromospheric components, the most involved species include Fe I blends and all prominent CH, NH, and CN spectral bands. Following the general trend seen in the solar "continuum," the variability of spectral lines also decreases toward longer wavelengths. The long-term solar cycle SSI changes are closely, to within the quoted 0.1%-0.2% uncertainties, matched by the appropriately adjusted short-term SSI variations derived from the 27 day rotational modulation cycles. This further strengthens and broadens the prevailing notion about the general scalability of the UV SSI variability to the emissivity changes in the Mg II 280 nm doublet on timescales from weeks to years. We also detect subtle deviations from this general rule: the prominent spectral lines and blends at lambda approximately or greater than 350 nm show slightly more pronounced 27 day SSI changes when compared to the long-term (years) trends. We merge the solar data from Cycle 21 with the current Cycle 24 OMI and GOME-2 observations and provide normalized SSI variations for the 170-795 nm spectral region.

  20. SOSPEX, an interactive tool to explore SOFIA spectral cubes

    Science.gov (United States)

    Fadda, Dario; Chambers, Edward T.

    2018-01-01

    We present SOSPEX (SOFIA SPectral EXplorer), an interactive tool to visualize and analyze spectral cubes obtained with the FIFI-LS and GREAT instruments onboard the SOFIA Infrared Observatory. This software package is written in Python 3 and it is available either through Github or Anaconda.Through this GUI it is possible to explore directly the spectral cubes produced by the SOFIA pipeline and archived in the SOFIA Science Archive. Spectral cubes are visualized showing their spatial and spectral dimensions in two different windows. By selecting a part of the spectrum, the flux from the corresponding slice of the cube is visualized in the spatial window. On the other hand, it is possible to define apertures on the spatial window to show the corresponding spectral energy distribution in the spectral window.Flux isocontours can be overlapped to external images in the spatial window while line names, atmospheric transmission, or external spectra can be overplotted on the spectral window. Atmospheric models with specific parameters can be retrieved, compared to the spectra and applied to the uncorrected FIFI-LS cubes in the cases where the standard values give unsatisfactory results. Subcubes can be selected and saved as FITS files by cropping or cutting the original cubes. Lines and continuum can be fitted in the spectral window saving the results in Jyson files which can be reloaded later. Finally, in the case of spatially extended observations, it is possible to compute spectral momenta as a function of the position to obtain velocity dispersion maps or velocity diagrams.

  1. Spectral imaging toolbox: segmentation, hyperstack reconstruction, and batch processing of spectral images for the determination of cell and model membrane lipid order.

    Science.gov (United States)

    Aron, Miles; Browning, Richard; Carugo, Dario; Sezgin, Erdinc; Bernardino de la Serna, Jorge; Eggeling, Christian; Stride, Eleanor

    2017-05-12

    Spectral imaging with polarity-sensitive fluorescent probes enables the quantification of cell and model membrane physical properties, including local hydration, fluidity, and lateral lipid packing, usually characterized by the generalized polarization (GP) parameter. With the development of commercial microscopes equipped with spectral detectors, spectral imaging has become a convenient and powerful technique for measuring GP and other membrane properties. The existing tools for spectral image processing, however, are insufficient for processing the large data sets afforded by this technological advancement, and are unsuitable for processing images acquired with rapidly internalized fluorescent probes. Here we present a MATLAB spectral imaging toolbox with the aim of overcoming these limitations. In addition to common operations, such as the calculation of distributions of GP values, generation of pseudo-colored GP maps, and spectral analysis, a key highlight of this tool is reliable membrane segmentation for probes that are rapidly internalized. Furthermore, handling for hyperstacks, 3D reconstruction and batch processing facilitates analysis of data sets generated by time series, z-stack, and area scan microscope operations. Finally, the object size distribution is determined, which can provide insight into the mechanisms underlying changes in membrane properties and is desirable for e.g. studies involving model membranes and surfactant coated particles. Analysis is demonstrated for cell membranes, cell-derived vesicles, model membranes, and microbubbles with environmentally-sensitive probes Laurdan, carboxyl-modified Laurdan (C-Laurdan), Di-4-ANEPPDHQ, and Di-4-AN(F)EPPTEA (FE), for quantification of the local lateral density of lipids or lipid packing. The Spectral Imaging Toolbox is a powerful tool for the segmentation and processing of large spectral imaging datasets with a reliable method for membrane segmentation and no ability in programming required. The

  2. Identification of meat products by shotgun spectral matching

    DEFF Research Database (Denmark)

    Ohana, D.; Dalebout, H.; Marissen, R. J.

    2016-01-01

    A new method, based on shotgun spectral matching of peptide tandem mass spectra, was successfully applied to the identification of different food species. The method was demonstrated to work on raw as well as processed samples from 16 mammalian and 10 bird species by counting spectral matches...... to spectral libraries in a reference database with one spectral library per species. A phylogenetic tree could also be constructed directly from the spectra. Nearly all samples could be correctly identified at the species level, and 100% at the genus level. The method does not use any genomic information...

  3. Spectral representations of neutron-star equations of state

    International Nuclear Information System (INIS)

    Lindblom, Lee

    2010-01-01

    Methods are developed for constructing spectral representations of cold (barotropic) neutron-star equations of state. These representations are faithful in the sense that every physical equation of state has a representation of this type and conversely every such representation satisfies the minimal thermodynamic stability criteria required of any physical equation of state. These spectral representations are also efficient, in the sense that only a few spectral coefficients are generally required to represent neutron-star equations of state quiet accurately. This accuracy and efficiency is illustrated by constructing spectral fits to a large collection of 'realistic' neutron-star equations of state.

  4. Spectral beam combining of diode lasers with high efficiency

    DEFF Research Database (Denmark)

    Müller, André; Vijayakumar, Deepak; Jensen, Ole Bjarlin

    2012-01-01

    Based on spectral beam combining we obtain 16 W of output power, combining two 1063 nm DBR-tapered diode lasers. The spectral separation within the combined beam can be used for subsequent sum-frequency generation.......Based on spectral beam combining we obtain 16 W of output power, combining two 1063 nm DBR-tapered diode lasers. The spectral separation within the combined beam can be used for subsequent sum-frequency generation....

  5. A spectral multiscale hybridizable discontinuous Galerkin method for second order elliptic problems

    KAUST Repository

    Efendiev, Yalchin R.

    2015-08-01

    We design a multiscale model reduction framework within the hybridizable discontinuous Galerkin finite element method. Our approach uses local snapshot spaces and local spectral decomposition following the concept of Generalized Multiscale Finite Element Methods. We propose several multiscale finite element spaces on the coarse edges that provide a reduced dimensional approximation for numerical traces within the HDG framework. We provide a general framework for systematic construction of multiscale trace spaces. Using local snapshots, we avoid high dimensional representation of trace spaces and use some local features of the solution space in constructing a low dimensional trace space. We investigate the solvability and numerically study the performance of the proposed method on a representative number of numerical examples.

  6. M3 spectral analysis of lunar swirls and the link between optical maturation and surface hydroxyl formation at magnetic anomalies

    Science.gov (United States)

    Kramer, G.Y.; Besse, S.; Dhingra, D.; Nettles, J.; Klima, R.; Garrick-Bethell, I.; Clark, Roger N.; Combe, J.-P.; Head, J. W.; Taylor, L.A.; Pieters, C.M.; Boardman, J.; McCord, T.B.

    2011-01-01

    from all three focus regions support the hypothesis that the magnetic anomalies deflect solar wind ions away from the swirls and onto off-swirl surfaces. Nanophase iron (npFe0) is largely responsible for the spectral characteristics we attribute to space weathering and maturation, and is created by vaporization/deposition by micrometeorite impacts and sputtering/reduction by solar wind ions. On the swirls, the decreased proton flux slows the spectral effects of space weathering (relative to nonswirl regions) by limiting the npFe0 production mechanism almost exclusively to micrometeoroid impact vaporization/deposition. Immediately adjacent to the swirls, maturation is accelerated by the increased flux of protons deflected from the swirls.

  7. Spectral Discrimination of Vegetation Classes in Ice-Free Areas of Antarctica

    Directory of Open Access Journals (Sweden)

    María Calviño-Cancela

    2016-10-01

    Full Text Available Detailed monitoring of vegetation changes in ice-free areas of Antarctica is crucial to determine the effects of climate warming and increasing human presence in this vulnerable ecosystem. Remote sensing techniques are especially suitable in this distant and rough environment, with high spectral and spatial resolutions needed owing to the patchiness and similarity between vegetation elements. We analyze the reflectance spectra of the most representative vegetation elements in ice-free areas of Antarctica to assess the potential for discrimination. This research is aimed as a basis for future aircraft/satellite research for long-term vegetation monitoring. The study was conducted in the Barton Peninsula, King George Island. The reflectance of ground patches of different types of vegetation or bare ground (c. 0.25 m 2 , n = 30 patches per class was recorded with a spectrophotometer measuring between 340 nm to 1025 nm at a resolution of 0.38 n m . We used Linear Discriminant Analysis (LDA to classify the cover classes according to reflectance spectra, after reduction of the number of bands using Principal Component Analysis (PCA. The first five principal components explained an accumulated 99.4% of the total variance and were added to the discriminant function. The LDA classification resulted in c. 92% of cases correctly classified (a hit ratio 11.9 times greater than chance. The most important region for discrimination was the visible and near ultraviolet (UV, with the relative importance of spectral bands steeply decreasing in the Near Infra-Red (NIR region. Our study shows the feasibility of discriminating among representative taxa of Antarctic vegetation using their spectral patterns in the near UV, visible and NIR. The results are encouraging for hyperspectral vegetation mapping in Antarctica, which could greatly facilitate monitoring vegetation changes in response to a changing environment, reducing the costs and environmental impacts of

  8. Estimating the Spectral Width of a Narrowband Optical Signal

    DEFF Research Database (Denmark)

    Lading, Lars; Skov Jensen, A.

    1980-01-01

    Methods for estimating the spectral width of a narrowband optical signal are investigated. Spectral analysis and Fourier spectroscopy are compared. Optimum and close-to-optimum estimators are developed under the constraint of having only one photodetector.......Methods for estimating the spectral width of a narrowband optical signal are investigated. Spectral analysis and Fourier spectroscopy are compared. Optimum and close-to-optimum estimators are developed under the constraint of having only one photodetector....

  9. Spectral line polarimetry with a channeled polarimeter.

    Science.gov (United States)

    van Harten, Gerard; Snik, Frans; Rietjens, Jeroen H H; Martijn Smit, J; Keller, Christoph U

    2014-07-01

    Channeled spectropolarimetry or spectral polarization modulation is an accurate technique for measuring the continuum polarization in one shot with no moving parts. We show how a dual-beam implementation also enables spectral line polarimetry at the intrinsic resolution, as in a classic beam-splitting polarimeter. Recording redundant polarization information in the two spectrally modulated beams of a polarizing beam-splitter even provides the possibility to perform a postfacto differential transmission correction that improves the accuracy of the spectral line polarimetry. We perform an error analysis to compare the accuracy of spectral line polarimetry to continuum polarimetry, degraded by a residual dark signal and differential transmission, as well as to quantify the impact of the transmission correction. We demonstrate the new techniques with a blue sky polarization measurement around the oxygen A absorption band using the groundSPEX instrument, yielding a polarization in the deepest part of the band of 0.160±0.010, significantly different from the polarization in the continuum of 0.2284±0.0004. The presented methods are applicable to any dual-beam channeled polarimeter, including implementations for snapshot imaging polarimetry.

  10. Scaling plant ultraviolet spectral responses from laboratory action spectra to field spectral weighting factors

    International Nuclear Information System (INIS)

    Flint, S.D.; Caldwell, M.M.

    1996-01-01

    Biological spectral weighting functions (BSWF) play a key role in calculating the increase of biologically effective solar ultraviolet-B radiation (UV-BBE) due to ozone reduction, assessing current latitudinal gradients of UV-B BE . and comparing solar UV-B BE with that from lamps and filters in plant experiments. Plant UV action spectra (usually determined with monochromatic radiation in the laboratory with exposure periods on the order of hours) are often used as BSWF. The realism of such spectra for plants growing day after day in polychromatic solar radiation in the field is questionable. We tested the widely used generalized plant action spectrum since preliminary data from an action spectrum being developed with monochromatic radiation for a cultivated oat variety indicate reasonable agreement with the generalized spectrum. These tests involved exposing plants to polychromatic radiation either from a high-pressure xenon arc lamp in growth chambers or in the field under solar radiation with supplemental UV-B lamps. Different broad-spectrum combinations were achieved by truncating the spectrum at successively longer UV wavelengths with various filters. In the growth chamber experiments, the generalized plant spectrum appeared to predict plant growth responses at short (<310nm) wavelengths but not at longer wavelengths. The field experiment reinforced these conclusions, showing (in addition to the expected direct UV-B effects) both direct UV-A effects and UV-A mitigation of UV-B effects. (author)

  11. SPAM- SPECTRAL ANALYSIS MANAGER (DEC VAX/VMS 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

  12. Biologically-inspired data decorrelation for hyper-spectral imaging

    Directory of Open Access Journals (Sweden)

    Ghita Ovidiu

    2011-01-01

    Full Text Available Abstract Hyper-spectral data allows the construction of more robust statistical models to sample the material properties than the standard tri-chromatic color representation. However, because of the large dimensionality and complexity of the hyper-spectral data, the extraction of robust features (image descriptors is not a trivial issue. Thus, to facilitate efficient feature extraction, decorrelation techniques are commonly applied to reduce the dimensionality of the hyper-spectral data with the aim of generating compact and highly discriminative image descriptors. Current methodologies for data decorrelation such as principal component analysis (PCA, linear discriminant analysis (LDA, wavelet decomposition (WD, or band selection methods require complex and subjective training procedures and in addition the compressed spectral information is not directly related to the physical (spectral characteristics associated with the analyzed materials. The major objective of this article is to introduce and evaluate a new data decorrelation methodology using an approach that closely emulates the human vision. The proposed data decorrelation scheme has been employed to optimally minimize the amount of redundant information contained in the highly correlated hyper-spectral bands and has been comprehensively evaluated in the context of non-ferrous material classification

  13. method for ranging and noise reduction of low coherence interferometry LCI and optical coherence tomography OCT signals by parallel detection of spectral bands

    NARCIS (Netherlands)

    Boer, JF De; Tearney, G. J.; Bouma, BE

    2008-01-01

    Apparatus and method for increasing the sensitivity in the detection of optical coherence tomography and loW coher ence interferometry (“LCI”) signals by detecting a parallel set of spectral bands, each band being a unique combination of optical frequencies. The LCI broad bandwidth source is split

  14. Relative spectral response calibration using Ti plasma lines

    Science.gov (United States)

    Teng, FEI; Congyuan, PAN; Qiang, ZENG; Qiuping, WANG; Xuewei, DU

    2018-04-01

    This work introduces the branching ratio (BR) method for determining relative spectral responses, which are needed routinely in laser induced breakdown spectroscopy (LIBS). Neutral and singly ionized Ti lines in the 250–498 nm spectral range are investigated by measuring laser-induced micro plasma near a Ti plate and used to calculate the relative spectral response of an entire LIBS detection system. The results are compared with those of the conventional relative spectral response calibration method using a tungsten halogen lamp, and certain lines available for the BR method are selected. The study supports the common manner of using BRs to calibrate the detection system in LIBS setups.

  15. In situ time-resolved X-ray near-edge absorption spectroscopy of selenite reduction by siderite

    International Nuclear Information System (INIS)

    Badaut, V.; Schlegel, M.L.; Descostes, M.; Moutiers, G.

    2012-01-01

    The reduction oxidation-reaction between aqueous selenite (SeO 3 2- ) and siderite (FeCO 3 (s)) was monitored by in situ, time-resolved X-ray absorption near-edge structure (XANES) spectroscopy at the selenium K edge in a controlled electrochemical environment. Spectral evolutions showed that more than 60% of selenite was reduced at the siderite surface after 20 h of experiment, at which time the reaction was still incomplete. Fitting of XANES spectra by linear combination of reference spectra showed that selenite reaction with siderite is essentially a two-step process, selenite ions being immobilized on siderite surface prior to their reduction. A kinetic model of the reduction step is proposed, allowing to identify the specific contribution of surface reduction. These results have strong implications for the retention of selenite by corrosion products in nuclear waste repositories and in a larger extent for the fate of selenium in the environment. (authors)

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

    Science.gov (United States)

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

    2003-06-01

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

  17. Spectral Textile Detection in the VNIR/SWIR Band

    Science.gov (United States)

    2015-03-01

    which have spectral similarities to background vegetation , are generally more difficult to detect than animal fibers such as wool and artificial fibers...effectiveness at long ranges, and spectral dismount detection currently relies on detecting skin pixels. In scenarios where skin is not exposed, spectral...training set. Classifiers with optimized parameters are used to classify contact data with artificially added noise and remotely-sensed hyperspectral data

  18. On Holo-Hilbert spectral analysis: a full informational spectral representation for nonlinear and non-stationary data

    OpenAIRE

    Huang, Norden E.; Hu, Kun; Yang, Albert C. C.; Chang, Hsing-Chih; Jia, Deng; Liang, Wei-Kuang; Yeh, Jia Rong; Kao, Chu-Lan; Juan, Chi-Hung; Peng, Chung Kang; Meijer, Johanna H.; Wang, Yung-Hung; Long, Steven R.; Wu, Zhauhua

    2016-01-01

    The Holo-Hilbert spectral analysis (HHSA) method is introduced to cure the deficiencies of traditional spectral analysis and to give a full informational representation of nonlinear and non-stationary data. It uses a nested empirical mode decomposition and Hilbert–Huang transform (HHT) approach to identify intrinsic amplitude and frequency modulations often present in nonlinear systems. Comparisons are first made with traditional spectrum analysis, which usually achieved its results through c...

  19. A Search for Hydrodynamical Interaction Between the ISM and Radio Jets in IC4296

    Science.gov (United States)

    Mackie, Glen

    1998-01-01

    The ROSAT HRI Data set on IC 4296 has been reduced and analysed. A draft paper on the small-scale structure of x-ray emission and its relation to the radio emission has been written. Mackie left the Smithsonian Astrophysical Observatory in September 1997 and in January 1998 he joined the staff at Carter Observatory, New Zealand. Mackie is currently (May 1998) upgrading computer software at Carter to run IRAF-PROS and XSPEC x-ray software packages in order to reduce and analyze archival ROSAT PSPC data on IC 4296. The PSPC results are needed to investigate the hot gas temperature and abundance properties that will be used in conjunction with the radio jet properties to determine the hydrodynamical interaction status of IC 4296, and finalize the results of a research paper.

  20. Spectral/hp element methods for CFD

    CERN Document Server

    Karniadakis, George Em

    1999-01-01

    Traditionally spectral methods in fluid dynamics were used in direct and large eddy simulations of turbulent flow in simply connected computational domains. The methods are now being applied to more complex geometries, and the spectral/hp element method, which incorporates both multi-domain spectral methods and high-order finite element methods, has been particularly successful. This book provides a comprehensive introduction to these methods. Written by leaders in the field, the book begins with a full explanation of fundamental concepts and implementation issues. It then illustrates how these methods can be applied to advection-diffusion and to incompressible and compressible Navier-Stokes equations. Drawing on both published and unpublished material, the book is an important resource for experienced researchers and for those new to the field.

  1. Spectral analysis by correlation

    International Nuclear Information System (INIS)

    Fauque, J.M.; Berthier, D.; Max, J.; Bonnet, G.

    1969-01-01

    The spectral density of a signal, which represents its power distribution along the frequency axis, is a function which is of great importance, finding many uses in all fields concerned with the processing of the signal (process identification, vibrational analysis, etc...). Amongst all the possible methods for calculating this function, the correlation method (correlation function calculation + Fourier transformation) is the most promising, mainly because of its simplicity and of the results it yields. The study carried out here will lead to the construction of an apparatus which, coupled with a correlator, will constitute a set of equipment for spectral analysis in real time covering the frequency range 0 to 5 MHz. (author) [fr

  2. Spectral, Electrochemical, Fluorescence, Kinetic and Anti-microbial Studies of Acyclic Schiff-base Gadolinium(III) Complexes

    International Nuclear Information System (INIS)

    Vijayaraj, A.; Prabu, R.; Suresh, R.; Narayanan, V.; Sangeetha Kumari, R.; Kaviyarasan, V.

    2012-01-01

    A new series of acyclic mononuclear gadolinium(III) complexes have been prepared by Schiff-base condensation derived from 5-methylsalicylaldehyde, diethylenetriamine, tris(2-aminoethyl) amine, triethylenetetramine, N,N-bis(3-aminopropyl)ethylene diamine, N,N-bis(aminopropyl) piperazine, and gadolinium nitrate. All the complexes were characterized by elemental and spectral analyses. Electronic spectra of the complexes show azomethine (CH=N) within the range of 410-420 nm. The fluorescence efficiency of Gd(III) ion in the cavity was completely quenched by the higher chain length ligands. Electrochemical studies of the complexes show irreversible one electron reduction process around -2.15 to -1.60 V. The reduction potential of gadolinium(III) complexes shifts towards anodic directions respectively upon increasing the chain length. The catalytic activity of the gadolinium(III) complexes on the hydrolysis of 4-nitrophenylphosphate was determined. All gadolinium(III) complexes were screened for antibacterial activity

  3. Spectral, Electrochemical, Fluorescence, Kinetic and Anti-microbial Studies of Acyclic Schiff-base Gadolinium(III) Complexes

    Energy Technology Data Exchange (ETDEWEB)

    Vijayaraj, A.; Prabu, R.; Suresh, R.; Narayanan, V.; Sangeetha Kumari, R.; Kaviyarasan, V. [Univ. of Madras, Madras (India)

    2012-11-15

    A new series of acyclic mononuclear gadolinium(III) complexes have been prepared by Schiff-base condensation derived from 5-methylsalicylaldehyde, diethylenetriamine, tris(2-aminoethyl) amine, triethylenetetramine, N,N-bis(3-aminopropyl)ethylene diamine, N,N-bis(aminopropyl) piperazine, and gadolinium nitrate. All the complexes were characterized by elemental and spectral analyses. Electronic spectra of the complexes show azomethine (CH=N) within the range of 410-420 nm. The fluorescence efficiency of Gd(III) ion in the cavity was completely quenched by the higher chain length ligands. Electrochemical studies of the complexes show irreversible one electron reduction process around -2.15 to -1.60 V. The reduction potential of gadolinium(III) complexes shifts towards anodic directions respectively upon increasing the chain length. The catalytic activity of the gadolinium(III) complexes on the hydrolysis of 4-nitrophenylphosphate was determined. All gadolinium(III) complexes were screened for antibacterial activity.

  4. Optimization of compressive 4D-spatio-spectral snapshot imaging

    Science.gov (United States)

    Zhao, Xia; Feng, Weiyi; Lin, Lihua; Su, Wu; Xu, Guoqing

    2017-10-01

    In this paper, a modified 3D computational reconstruction method in the compressive 4D-spectro-volumetric snapshot imaging system is proposed for better sensing spectral information of 3D objects. In the design of the imaging system, a microlens array (MLA) is used to obtain a set of multi-view elemental images (EIs) of the 3D scenes. Then, these elemental images with one dimensional spectral information and different perspectives are captured by the coded aperture snapshot spectral imager (CASSI) which can sense the spectral data cube onto a compressive 2D measurement image. Finally, the depth images of 3D objects at arbitrary depths, like a focal stack, are computed by inversely mapping the elemental images according to geometrical optics. With the spectral estimation algorithm, the spectral information of 3D objects is also reconstructed. Using a shifted translation matrix, the contrast of the reconstruction result is further enhanced. Numerical simulation results verify the performance of the proposed method. The system can obtain both 3D spatial information and spectral data on 3D objects using only one single snapshot, which is valuable in the agricultural harvesting robots and other 3D dynamic scenes.

  5. Spectral Band Characterization for Hyperspectral Monitoring of Water Quality

    Science.gov (United States)

    Vermillion, Stephanie C.; Raqueno, Rolando; Simmons, Rulon

    2001-01-01

    A method for selecting the set of spectral characteristics that provides the smallest increase in prediction error is of interest to those using hyperspectral imaging (HSI) to monitor water quality. The spectral characteristics of interest to these applications are spectral bandwidth and location. Three water quality constituents of interest that are detectable via remote sensing are chlorophyll (CHL), total suspended solids (TSS), and colored dissolved organic matter (CDOM). Hyperspectral data provides a rich source of information regarding the content and composition of these materials, but often provides more data than an analyst can manage. This study addresses the spectral characteristics need for water quality monitoring for two reasons. First, determination of the greatest contribution of these spectral characteristics would greatly improve computational ease and efficiency. Second, understanding the spectral capabilities of different spectral resolutions and specific regions is an essential part of future system development and characterization. As new systems are developed and tested, water quality managers will be asked to determine sensor specifications that provide the most accurate and efficient water quality measurements. We address these issues using data from the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) and a set of models to predict constituent concentrations.

  6. On the spectral composition of global radiation

    Energy Technology Data Exchange (ETDEWEB)

    Major, G

    1983-01-01

    The global radiation is recorded at several stations on the Earth. The information about its spectral composition is poor. In this paper the spectral composition means the ratio of spectral global radiation measured by coloured glass filter domes to the total global radiation. From the measuements made by Klein and Goldberg it follows that the monthly ratios vary significantly from place to place, while the variations from month to month at one place are significant only at the station which lies near to the North Pole. The Budapest data proved the dominant effect of cloudiness on the spectral composition of global radiation. This effect is in good statistical relationship with the relative global radiation. The regression constant tabulated in this paper do not contain the error of zero point elevation which is due to the overheating of glass filters by the absorbed solar radiation.

  7. Digital spectral analysis parametric, non-parametric and advanced methods

    CERN Document Server

    Castanié, Francis

    2013-01-01

    Digital Spectral Analysis provides a single source that offers complete coverage of the spectral analysis domain. This self-contained work includes details on advanced topics that are usually presented in scattered sources throughout the literature.The theoretical principles necessary for the understanding of spectral analysis are discussed in the first four chapters: fundamentals, digital signal processing, estimation in spectral analysis, and time-series models.An entire chapter is devoted to the non-parametric methods most widely used in industry.High resolution methods a

  8. Low-Cost Spectral Sensor Development Description.

    Energy Technology Data Exchange (ETDEWEB)

    Armijo, Kenneth Miguel; Yellowhair, Julius

    2014-11-01

    Solar spectral data for all parts of the US is limited due in part to the high cost of commercial spectrometers. Solar spectral information is necessary for accurate photovoltaic (PV) performance forecasting, especially for large utility-scale PV installations. A low-cost solar spectral sensor would address the obstacles and needs. In this report, a novel low-cost, discrete- band sensor device, comprised of five narrow-band sensors, is described. The hardware is comprised of commercial-off-the-shelf components to keep the cost low. Data processing algorithms were developed and are being refined for robustness. PV module short-circuit current ( I sc ) prediction methods were developed based on interaction-terms regression methodology and spectrum reconstruction methodology for computing I sc . The results suggest the computed spectrum using the reconstruction method agreed well with the measured spectrum from the wide-band spectrometer (RMS error of 38.2 W/m 2 -nm). Further analysis of computed I sc found a close correspondence of 0.05 A RMS error. The goal is for ubiquitous adoption of the low-cost spectral sensor in solar PV and other applications such as weather forecasting.

  9. Vowel reduction in word-final position by early and late Spanish-English bilinguals

    Science.gov (United States)

    2017-01-01

    Vowel reduction is a prominent feature of American English, as well as other stress-timed languages. As a phonological process, vowel reduction neutralizes multiple vowel quality contrasts in unstressed syllables. For bilinguals whose native language is not characterized by large spectral and durational differences between tonic and atonic vowels, systematically reducing unstressed vowels to the central vowel space can be problematic. Failure to maintain this pattern of stressed-unstressed syllables in American English is one key element that contributes to a “foreign accent” in second language speakers. Reduced vowels, or “schwas,” have also been identified as particularly vulnerable to the co-articulatory effects of adjacent consonants. The current study examined the effects of adjacent sounds on the spectral and temporal qualities of schwa in word-final position. Three groups of English-speaking adults were tested: Miami-based monolingual English speakers, early Spanish-English bilinguals, and late Spanish-English bilinguals. Subjects performed a reading task to examine their schwa productions in fluent speech when schwas were preceded by consonants from various points of articulation. Results indicated that monolingual English and late Spanish-English bilingual groups produced targeted vowel qualities for schwa, whereas early Spanish-English bilinguals lacked homogeneity in their vowel productions. This extends prior claims that schwa is targetless for F2 position for native speakers to highly-proficient bilingual speakers. Though spectral qualities lacked homogeneity for early Spanish-English bilinguals, early bilinguals produced schwas with near native-like vowel duration. In contrast, late bilinguals produced schwas with significantly longer durations than English monolinguals or early Spanish-English bilinguals. Our results suggest that the temporal properties of a language are better integrated into second language phonologies than spectral

  10. Spectral evolution of galaxies: current views

    International Nuclear Information System (INIS)

    Bruzual, A.G.

    1985-01-01

    A summary of current views on the interpretation of the various evolutionary tests aimed at detecting spectral evolution in galaxies is presented. It is concluded that the evolution taking place in known galaxy samples is a slow process (perhaps consistent with no evolution at all), and that the early phases of rapid spectral evolution in early-type galaxies have not yet been detected. (author)

  11. Normal form theory and spectral sequences

    OpenAIRE

    Sanders, Jan A.

    2003-01-01

    The concept of unique normal form is formulated in terms of a spectral sequence. As an illustration of this technique some results of Baider and Churchill concerning the normal form of the anharmonic oscillator are reproduced. The aim of this paper is to show that spectral sequences give us a natural framework in which to formulate normal form theory. © 2003 Elsevier Science (USA). All rights reserved.

  12. Online Multi-Spectral Meat Inspection

    DEFF Research Database (Denmark)

    Nielsen, Jannik Boll; Larsen, Anders Boesen Lindbo

    2013-01-01

    We perform an explorative study on multi-spectral image data from a prototype device developed for fast online quality inspection of meat products. Because the camera setup is built for speed, we sacrifice exact pixel correspondences between the different bands of the multi-spectral images. Our...... work is threefold as we 1) investigate the color distributions and construct a model to describe pork loins, 2) classify the different components in pork loins (meat, fat, membrane), and 3) detect foreign objects on the surface of pork loins. Our investigation shows that the color distributions can...

  13. Berlin Reflectance Spectral Library (BRSL)

    Science.gov (United States)

    Henckel, D.; Arnold, G.; Kappel, D.; Moroz, L. V.; Markus, K.

    2017-09-01

    The Berlin Reflectance Spectral Library (BRSL) provides a collection of reflectance spectra between 0.3 and 17 µm. It was originally dedicated to support space missions to small solar system bodies. Meanwhile the library includes selections of biconical reflectance spectra for spectral data analysis of other planetary bodies as well. The library provides reference spectra of well-characterized terrestrial analogue materials and meteorites for interpretation of remote sensing reflectance spectra of planetary surfaces. We introduce the BRSL, summarize the data available, and access to use them for further relevant applications.

  14. Spectral ellipsometry of nanodiamond composite

    International Nuclear Information System (INIS)

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

    2006-01-01

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

  15. Towards spectral geometric methods for Euclidean quantum gravity

    Science.gov (United States)

    Panine, Mikhail; Kempf, Achim

    2016-04-01

    The unification of general relativity with quantum theory will also require a coming together of the two quite different mathematical languages of general relativity and quantum theory, i.e., of differential geometry and functional analysis, respectively. Of particular interest in this regard is the field of spectral geometry, which studies to which extent the shape of a Riemannian manifold is describable in terms of the spectra of differential operators defined on the manifold. Spectral geometry is hard because it is highly nonlinear, but linearized spectral geometry, i.e., the task to determine small shape changes from small spectral changes, is much more tractable and may be iterated to approximate the full problem. Here, we generalize this approach, allowing, in particular, nonequal finite numbers of shape and spectral degrees of freedom. This allows us to study how well the shape degrees of freedom are encoded in the eigenvalues. We apply this strategy numerically to a class of planar domains and find that the reconstruction of small shape changes from small spectral changes is possible if enough eigenvalues are used. While isospectral nonisometric shapes are known to exist, we find evidence that generically shaped isospectral nonisometric shapes, if existing, are exceedingly rare.

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

    International Nuclear Information System (INIS)

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

    2013-01-01

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

  17. WE-FG-207B-12: Quantitative Evaluation of a Spectral CT Scanner in a Phantom Study: Results of Spectral Reconstructions

    International Nuclear Information System (INIS)

    Duan, X; Arbique, G; Guild, J; Anderson, J; Yagil, Y

    2016-01-01

    Purpose: To evaluate the quantitative image quality of spectral reconstructions of phantom data from a spectral CT scanner. Methods: The spectral CT scanner (IQon Spectral CT, Philips Healthcare) is equipped with a dual-layer detector and generates conventional 80-140 kVp images and variety of spectral reconstructions, e.g., virtual monochromatic (VM) images, virtual non-contrast (VNC) images, iodine maps, and effective atomic number (Z) images. A cylindrical solid water phantom (Gammex 472, 33 cm diameter and 5 cm thick) with iodine (2.0-20.0 mg I/ml) and calcium (50-600 mg/ml) rod inserts was scanned at 120 kVp and 27 mGy CTDIvol. Spectral reconstructions were evaluated by comparing image measurements with theoretical values calculated from nominal rod compositions provided by the phantom manufacturer. The theoretical VNC was calculated using water and iodine basis material decomposition, and the theoretical Z was calculated using two common methods, the chemical formula method (Z1) and the dual-energy ratio method (Z2). Results: Beam-hardening-like artifacts between high-attenuation calcium rods (≥300 mg/ml, >800 HU) influenced quantitative measurements, so the quantitative analysis was only performed on iodine rods using the images from the scan with all the calcium rods removed. The CT numbers of the iodine rods in the VM images (50∼150 keV) were close to theoretical values with average difference of 2.4±6.9 HU. Compared with theoretical values, the average difference for iodine concentration, VNC CT number and effective Z of iodine rods were −0.10±0.38 mg/ml, −0.1±8.2 HU, 0.25±0.06 (Z1) and −0.23±0.07 (Z2). Conclusion: The results indicate that the spectral CT scanner generates quantitatively accurate spectral reconstructions at clinically relevant iodine concentrations. Beam-hardening-like artifacts still exist when high-attenuation objects are present and their impact on patient images needs further investigation. YY is an employee of Philips

  18. WE-FG-207B-12: Quantitative Evaluation of a Spectral CT Scanner in a Phantom Study: Results of Spectral Reconstructions

    Energy Technology Data Exchange (ETDEWEB)

    Duan, X; Arbique, G; Guild, J; Anderson, J [UT Southwestern Medical Center, Dallas, TX (United States); Yagil, Y [Philips Healthcare, Haifa (Israel)

    2016-06-15

    Purpose: To evaluate the quantitative image quality of spectral reconstructions of phantom data from a spectral CT scanner. Methods: The spectral CT scanner (IQon Spectral CT, Philips Healthcare) is equipped with a dual-layer detector and generates conventional 80-140 kVp images and variety of spectral reconstructions, e.g., virtual monochromatic (VM) images, virtual non-contrast (VNC) images, iodine maps, and effective atomic number (Z) images. A cylindrical solid water phantom (Gammex 472, 33 cm diameter and 5 cm thick) with iodine (2.0-20.0 mg I/ml) and calcium (50-600 mg/ml) rod inserts was scanned at 120 kVp and 27 mGy CTDIvol. Spectral reconstructions were evaluated by comparing image measurements with theoretical values calculated from nominal rod compositions provided by the phantom manufacturer. The theoretical VNC was calculated using water and iodine basis material decomposition, and the theoretical Z was calculated using two common methods, the chemical formula method (Z1) and the dual-energy ratio method (Z2). Results: Beam-hardening-like artifacts between high-attenuation calcium rods (≥300 mg/ml, >800 HU) influenced quantitative measurements, so the quantitative analysis was only performed on iodine rods using the images from the scan with all the calcium rods removed. The CT numbers of the iodine rods in the VM images (50∼150 keV) were close to theoretical values with average difference of 2.4±6.9 HU. Compared with theoretical values, the average difference for iodine concentration, VNC CT number and effective Z of iodine rods were −0.10±0.38 mg/ml, −0.1±8.2 HU, 0.25±0.06 (Z1) and −0.23±0.07 (Z2). Conclusion: The results indicate that the spectral CT scanner generates quantitatively accurate spectral reconstructions at clinically relevant iodine concentrations. Beam-hardening-like artifacts still exist when high-attenuation objects are present and their impact on patient images needs further investigation. YY is an employee of Philips

  19. Dimensionality reduction of collective motion by principal manifolds

    Science.gov (United States)

    Gajamannage, Kelum; Butail, Sachit; Porfiri, Maurizio; Bollt, Erik M.

    2015-01-01

    While the existence of low-dimensional embedding manifolds has been shown in patterns of collective motion, the current battery of nonlinear dimensionality reduction methods is not amenable to the analysis of such manifolds. This is mainly due to the necessary spectral decomposition step, which limits control over the mapping from the original high-dimensional space to the embedding space. Here, we propose an alternative approach that demands a two-dimensional embedding which topologically summarizes the high-dimensional data. In this sense, our approach is closely related to the construction of one-dimensional principal curves that minimize orthogonal error to data points subject to smoothness constraints. Specifically, we construct a two-dimensional principal manifold directly in the high-dimensional space using cubic smoothing splines, and define the embedding coordinates in terms of geodesic distances. Thus, the mapping from the high-dimensional data to the manifold is defined in terms of local coordinates. Through representative examples, we show that compared to existing nonlinear dimensionality reduction methods, the principal manifold retains the original structure even in noisy and sparse datasets. The principal manifold finding algorithm is applied to configurations obtained from a dynamical system of multiple agents simulating a complex maneuver called predator mobbing, and the resulting two-dimensional embedding is compared with that of a well-established nonlinear dimensionality reduction method.

  20. Feasibility of spectral shaping for detection and quantification of coronary calcifications in ultra-low dose CT

    Energy Technology Data Exchange (ETDEWEB)

    Vonder, Marleen; Pelgrim, Gert Jan; Vliegenthart, Rozemarijn [University of Groningen, University Medical Center Groningen, Department of Radiology, Groningen (Netherlands); University of Groningen, University Medical Center Groningen, Center for Medical Imaging North-East Netherlands (CMI-NEN), Groningen (Netherlands); Huijsse, Sevrin E.M.; Greuter, Marcel J.W. [University of Groningen, University Medical Center Groningen, Department of Radiology, Groningen (Netherlands); Meyer, Mathias; Henzler, Thomas [Heidelberg University, Institute of Clinical Radiology and Nuclear Medicine, Medical Faculty Mannheim, University Medical Center Mannheim, Heidelberg (Germany); Flohr, Thomas G. [Siemens Healthcare GmbH, Computed Tomography, Forchheim (Germany); Oudkerk, Matthijs [University of Groningen, University Medical Center Groningen, Center for Medical Imaging North-East Netherlands (CMI-NEN), Groningen (Netherlands)

    2017-05-15

    To evaluate detectability and quantification of coronary calcifications for CT with a tin filter for spectral shaping. Phantom inserts with 100 small and 9 large calcifications, and a moving artificial artery with 3 calcifications (speed 0-30 mm/s) were placed in a thorax phantom simulating different patient sizes. The phantom was scanned in high-pitch spiral mode at 100 kVp with tin filter (Sn100 kVp), and at a reference of 120 kVp, with electrocardiographic (ECG) gating. Detectability and quantification of calcifications were analyzed for standard (130 HU) and adapted thresholds. Sn100 kVp yielded lower detectability of calcifications (9 % versus 12 %, p = 0.027) and lower Agatston scores (p < 0.008), irrespective of calcification, patient size and speed. Volume scores of the moving calcifications for Sn100 kVp at speed 10-30 mm/s were lower (p < 0.001), while mass scores were similar (p = 0.131). For Sn100 kVp with adapted threshold of 117 HU, detectability (p = 1.000) and Agatston score (p > 0.206) were similar to 120 kVp. Spectral shaping resulted in median dose reduction of 62.3 % (range 59.0-73.4 %). Coronary calcium scanning with spectral shaping yields lower detectability of calcifications and lower Agatston scores compared to 120 kVp scanning, for which a HU threshold correction should be developed. (orig.)

  1. On Pythagoras Theorem for Products of Spectral Triples

    OpenAIRE

    D'Andrea, Francesco; Martinetti, Pierre

    2013-01-01

    We discuss a version of Pythagoras theorem in noncommutative geometry. Usual Pythagoras theorem can be formulated in terms of Connes' distance, between pure states, in the product of commutative spectral triples. We investigate the generalization to both non pure states and arbitrary spectral triples. We show that Pythagoras theorem is replaced by some Pythagoras inequalities, that we prove for the product of arbitrary (i.e. non-necessarily commutative) spectral triples, assuming only some un...

  2. Spectral Action for Torsion with and without Boundaries

    DEFF Research Database (Denmark)

    Iochum, B.; Levy, Cyril Olivier; Vassilevich, D.

    2012-01-01

    We derive a commutative spectral triple and study the spectral action for a rather general geometric setting which includes the (skew-symmetric) torsion and the chiral bag conditions on the boundary. The spectral action splits into bulk and boundary parts. In the bulk, we clarify certain issues...... of the boundary conditions, and show that θ = 0 is a critical point of the action in any dimension and at all orders of the expansion....

  3. The effect of host star spectral energy distribution and ice-albedo feedback on the climate of extrasolar planets.

    Science.gov (United States)

    Shields, Aomawa L; Meadows, Victoria S; Bitz, Cecilia M; Pierrehumbert, Raymond T; Joshi, Manoj M; Robinson, Tyler D

    2013-08-01

    Planetary climate can be affected by the interaction of the host star spectral energy distribution with the wavelength-dependent reflectivity of ice and snow. In this study, we explored this effect with a one-dimensional (1-D), line-by-line, radiative transfer model to calculate broadband planetary albedos as input to a seasonally varying, 1-D energy balance climate model. A three-dimensional (3-D) general circulation model was also used to explore the atmosphere's response to changes in incoming stellar radiation, or instellation, and surface albedo. Using this hierarchy of models, we simulated planets covered by ocean, land, and water-ice of varying grain size, with incident radiation from stars of different spectral types. Terrestrial planets orbiting stars with higher near-UV radiation exhibited a stronger ice-albedo feedback. We found that ice extent was much greater on a planet orbiting an F-dwarf star than on a planet orbiting a G-dwarf star at an equivalent flux distance, and that ice-covered conditions occurred on an F-dwarf planet with only a 2% reduction in instellation relative to the present instellation on Earth, assuming fixed CO(2) (present atmospheric level on Earth). A similar planet orbiting the Sun at an equivalent flux distance required an 8% reduction in instellation, while a planet orbiting an M-dwarf star required an additional 19% reduction in instellation to become ice-covered, equivalent to 73% of the modern solar constant. The reduction in instellation must be larger for planets orbiting cooler stars due in large part to the stronger absorption of longer-wavelength radiation by icy surfaces on these planets in addition to stronger absorption by water vapor and CO(2) in their atmospheres, which provides increased downwelling longwave radiation. Lowering the IR and visible-band surface ice and snow albedos for an M-dwarf planet increased the planet's climate stability against changes in instellation and slowed the descent into global ice

  4. Introduction to finite and spectral element methods using Matlab

    CERN Document Server

    Pozrikidis, Constantine

    2014-01-01

    The Finite Element Method in One Dimension. Further Applications in One Dimension. High-Order and Spectral Elements in One Dimension. The Finite Element Method in Two Dimensions. Quadratic and Spectral Elements in Two Dimensions. Applications in Mechanics. Viscous Flow. Finite and Spectral Element Methods in Three Dimensions. Appendices. References. Index.

  5. Neural networks for the dimensionality reduction of GOME measurement vector in the estimation of ozone profiles

    International Nuclear Information System (INIS)

    Del Frate, F.; Iapaolo, M.; Casadio, S.; Godin-Beekmann, S.; Petitdidier, M.

    2005-01-01

    Dimensionality reduction can be of crucial importance in the application of inversion schemes to atmospheric remote sensing data. In this study the problem of dimensionality reduction in the retrieval of ozone concentration profiles from the radiance measurements provided by the instrument Global Ozone Monitoring Experiment (GOME) on board of ESA satellite ERS-2 is considered. By means of radiative transfer modelling, neural networks and pruning algorithms, a complete procedure has been designed to extract the GOME spectral ranges most crucial for the inversion. The quality of the resulting retrieval algorithm has been evaluated by comparing its performance to that yielded by other schemes and co-located profiles obtained with lidar measurements

  6. Electrophysiological measurements of spectral sensitivities: a review

    Directory of Open Access Journals (Sweden)

    R.D. DeVoe

    1997-02-01

    Full Text Available Spectral sensitivities of visual systems are specified as the reciprocals of the intensities of light (quantum fluxes needed at each wavelength to elicit the same criterion amplitude of responses. This review primarily considers the methods that have been developed for electrophysiological determinations of criterion amplitudes of slow-wave responses from single retinal cells. Traditional flash methods can require tedious dark adaptations and may yield erroneous spectral sensitivity curves which are not seen in such modifications as ramp methods. Linear response methods involve interferometry, while constant response methods involve manual or automatic adjustments of continuous illumination to keep response amplitudes constant during spectral scans. In DC or AC computerized constant response methods, feedback to determine intensities at each wavelength is derived from the response amplitudes themselves. Although all but traditional flash methods have greater or lesser abilities to provide on-line determinations of spectral sensitivities, computerized constant response methods are the most satisfactory due to flexibility, speed and maintenance of a constant adaptation level

  7. Spectral properties of the massless relativistic quartic oscillator

    Science.gov (United States)

    Durugo, Samuel O.; Lőrinczi, József

    2018-03-01

    An explicit solution of the spectral problem of the non-local Schrödinger operator obtained as the sum of the square root of the Laplacian and a quartic potential in one dimension is presented. The eigenvalues are obtained as zeroes of special functions related to the fourth order Airy function, and closed formulae for the Fourier transform of the eigenfunctions are derived. These representations allow to derive further spectral properties such as estimates of spectral gaps, heat trace and the asymptotic distribution of eigenvalues, as well as a detailed analysis of the eigenfunctions. A subtle spectral effect is observed which manifests in an exponentially tight approximation of the spectrum by the zeroes of the dominating term in the Fourier representation of the eigenfunctions and its derivative.

  8. A Spectral Emissivity Library of Spoil Substrates

    Czech Academy of Sciences Publication Activity Database

    Pivovarník, Marek; Pikl, Miroslav; Frouz, J.; Zemek, František; Kopačková, V.; Notesco, G.; Ben Dor, E.

    2016-01-01

    Roč. 1, č. 2 (2016) E-ISSN 2306-5729 R&D Projects: GA MŠk(CZ) LO1415 Institutional support: RVO:86652079 Keywords : post-mining sites * spectral emissivity * spectral library * spoil substrates Subject RIV: EH - Ecology, Behaviour OBOR OECD: Environmental sciences (social aspects to be 5.7)

  9. Toward optimal spatial and spectral quality in widefield infrared spectromicroscopy of IR labelled single cells.

    Science.gov (United States)

    Mattson, Eric C; Unger, Miriam; Clède, Sylvain; Lambert, François; Policar, Clotilde; Imtiaz, Asher; D'Souza, Roshan; Hirschmugl, Carol J

    2013-10-07

    Advancements in widefield infrared spectromicroscopy have recently been demonstrated following the commissioning of IRENI (InfraRed ENvironmental Imaging), a Fourier Transform infrared (FTIR) chemical imaging beamline at the Synchrotron Radiation Center. The present study demonstrates the effects of magnification, spatial oversampling, spectral pre-processing and deconvolution, focusing on the intracellular detection and distribution of an exogenous metal tris-carbonyl derivative 1 in a single MDA-MB-231 breast cancer cell. We demonstrate here that spatial oversampling for synchrotron-based infrared imaging is critical to obtain accurate diffraction-limited images at all wavelengths simultaneously. Resolution criteria and results from raw and deconvoluted images for two Schwarzschild objectives (36×, NA 0.5 and 74×, NA 0.65) are compared to each other and to prior reports for raster-scanned, confocal microscopes. The resolution of the imaging data can be improved by deconvolving the instrumental broadening that is determined with the measured PSFs, which is implemented with GPU programming architecture for fast hyperspectral processing. High definition, rapidly acquired, FTIR chemical images of respective spectral signatures of the cell 1 and shows that 1 is localized next to the phosphate- and Amide-rich regions, in agreement with previous infrared and luminescence studies. The infrared image contrast, localization and definition are improved after applying proven spectral pre-processing (principal component analysis based noise reduction and RMie scattering correction algorithms) to individual pixel spectra in the hyperspectral cube.

  10. Behaviour of spectral entropy, spectral edge frequency 90%, and alpha and beta power parameters during low-dose propofol infusion.

    LENUS (Irish Health Repository)

    Mahon, P

    2012-02-03

    BACKGROUND: In this study we analyse the behaviour, potential clinical application and optimal cortical sampling location of the spectral parameters: (i) relative alpha and beta power; (ii) spectral edge frequency 90%; and (iii) spectral entropy as monitors of moderate propofol-induced sedation. METHODS: Multi-channel EEG recorded from 12 ASA 1 (American Society of Anesthesiologists physical status 1) patients during low-dose, target effect-site controlled propofol infusion was used for this analysis. The initial target effect-site concentration was 0.5 microg ml(-1) and increased at 4 min intervals in increments of 0.5 to 2 microg ml(-1). EEG parameters were calculated for 2 s epochs in the frequency ranges 0.5-32 and 0.5-47 Hz. All parameters were calculated in the channels: P4-O2, P3-O1, F4-C4, F3-C3, F3-F4, and Fp1-Fp2. Sedation was assessed clinically using the OAA\\/S (observer\\'s assessment of alertness\\/sedation) scale. RESULTS: Relative beta power and spectral entropy increased with increasing propofol effect-site concentration in both the 0.5-47 Hz [F(18, 90) = 3.455, P<0.05 and F(18, 90) = 3.33, P<0.05, respectively] and 0.5-32 Hz frequency range. This effect was significant in each individual channel (P<0.05). No effect was seen of increasing effect-site concentration on relative power in the alpha band. Averaged across all channels, spectral entropy did not outperform relative beta power in either the 0.5-32 Hz [Pk=0.79 vs 0.814 (P>0.05)] or 0.5-47 Hz range [Pk=0.81 vs 0.82 (P>0.05)]. The best performing indicator in any single channel was spectral entropy in the frequency range 0.5-47 Hz in the frontal channel F3-F4 (Pk=0.85). CONCLUSIONS: Relative beta power and spectral entropy when considered over the propofol effect-site range studied here increase in value, and correlate well with clinical assessment of sedation.

  11. Effective spectral function for quasielastic scattering on nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Bodek, A.; Coopersmith, B. [University of Rochester, Department of Physics and Astronomy, Rochester, NY (United States); Christy, M.E. [Hampton University, Hampton, VA (United States)

    2014-10-15

    Spectral functions that are used in neutrino event, generators to model quasielastic (QE) scattering from nuclear targets include Fermi gas, Local Thomas Fermi gas (LTF), Bodek-Ritchie Fermi gas with high momentum tail, and the Benhar-Fantoni two dimensional spectral function. We find that the ν dependence of predictions of these spectral functions for the QE differential cross sections (d{sup 2}σ/dQ{sup 2}dν) are in disagreement with the prediction of the ψ' superscaling function which is extracted from fits to quasielastic electron scattering data on nuclear targets. It is known that spectral functions do not fully describe quasielastic scattering because they only model the initial state. Final state interactions distort the shape of the differential cross section at the peak and increase the cross section at the tails of the distribution. We show that the kinematic distributions predicted by the ψ' superscaling formalism can be well described with a modified effective spectral function (ESF). By construction, models using ESF in combination with the transverse enhancement contribution correctly predict electron QE scattering data. (orig.)

  12. Effective spectral function for quasielastic scattering on nuclei

    International Nuclear Information System (INIS)

    Bodek, A.; Coopersmith, B.; Christy, M.E.

    2014-01-01

    Spectral functions that are used in neutrino event, generators to model quasielastic (QE) scattering from nuclear targets include Fermi gas, Local Thomas Fermi gas (LTF), Bodek-Ritchie Fermi gas with high momentum tail, and the Benhar-Fantoni two dimensional spectral function. We find that the ν dependence of predictions of these spectral functions for the QE differential cross sections (d 2 σ/dQ 2 dν) are in disagreement with the prediction of the ψ' superscaling function which is extracted from fits to quasielastic electron scattering data on nuclear targets. It is known that spectral functions do not fully describe quasielastic scattering because they only model the initial state. Final state interactions distort the shape of the differential cross section at the peak and increase the cross section at the tails of the distribution. We show that the kinematic distributions predicted by the ψ' superscaling formalism can be well described with a modified effective spectral function (ESF). By construction, models using ESF in combination with the transverse enhancement contribution correctly predict electron QE scattering data. (orig.)

  13. Spectral Inverse Quantum (Spectral-IQ Method for Modeling Mesoporous Systems: Application on Silica Films by FTIR

    Directory of Open Access Journals (Sweden)

    Mihai V. Putz

    2012-11-01

    Full Text Available The present work advances the inverse quantum (IQ structural criterion for ordering and characterizing the porosity of the mesosystems based on the recently advanced ratio of the particle-to-wave nature of quantum objects within the extended Heisenberg uncertainty relationship through employing the quantum fluctuation, both for free and observed quantum scattering information, as computed upon spectral identification of the wave-numbers specific to the maximum of absorption intensity record, and to left-, right- and full-width at the half maximum (FWHM of the concerned bands of a given compound. It furnishes the hierarchy for classifying the mesoporous systems from more particle-related (porous, tight or ionic bindings to more wave behavior (free or covalent bindings. This so-called spectral inverse quantum (Spectral-IQ particle-to-wave assignment was illustrated on spectral measurement of FT-IR (bonding bands’ assignment for samples synthesized within different basic environment and different thermal treatment on mesoporous materials obtained by sol-gel technique with n-dodecyl trimethyl ammonium bromide (DTAB and cetyltrimethylammonium bromide (CTAB and of their combination as cosolvents. The results were analyzed in the light of the so-called residual inverse quantum information, accounting for the free binding potency of analyzed samples at drying temperature, and were checked by cross-validation with thermal decomposition techniques by endo-exo thermo correlations at a higher temperature.

  14. Sparse spectral deconvolution algorithm for noncartesian MR spectroscopic imaging.

    Science.gov (United States)

    Bhave, Sampada; Eslami, Ramin; Jacob, Mathews

    2014-02-01

    To minimize line shape distortions and spectral leakage artifacts in MR spectroscopic imaging (MRSI). A spatially and spectrally regularized non-Cartesian MRSI algorithm that uses the line shape distortion priors, estimated from water reference data, to deconvolve the spectra is introduced. Sparse spectral regularization is used to minimize noise amplification associated with deconvolution. A spiral MRSI sequence that heavily oversamples the central k-space regions is used to acquire the MRSI data. The spatial regularization term uses the spatial supports of brain and extracranial fat regions to recover the metabolite spectra and nuisance signals at two different resolutions. Specifically, the nuisance signals are recovered at the maximum resolution to minimize spectral leakage, while the point spread functions of metabolites are controlled to obtain acceptable signal-to-noise ratio. The comparisons of the algorithm against Tikhonov regularized reconstructions demonstrates considerably reduced line-shape distortions and improved metabolite maps. The proposed sparsity constrained spectral deconvolution scheme is effective in minimizing the line-shape distortions. The dual resolution reconstruction scheme is capable of minimizing spectral leakage artifacts. Copyright © 2013 Wiley Periodicals, Inc.

  15. Is spectral reflectance of the face a reliable biometric?

    Science.gov (United States)

    Uzair, Muhammad; Mahmood, Arif; Shafait, Faisal; Nansen, Christian; Mian, Ajmal

    2015-06-15

    Over a decade ago, Pan et al. [IEEE TPAMI 25, 1552 (2003)] performed face recognition using only the spectral reflectance of the face at six points and reported around 95% recognition rate. Since their database is private, no one has been able to replicate these results. Moreover, due to the unavailability of public datasets, there has been no detailed study in the literature on the viability of facial spectral reflectance for person identification. In this study, we introduce a new public database of facial spectral reflectance profiles measured with a high precision spectrometer. For each of the 40 subjects, spectral reflectance was measured at the same six points as Pan et al. [IEEE TPAMI 25, 1552 (2003)] in multiple sessions and with time lapse. Furthermore, we sample the facial spectral reflectance from two public hyperspectral face image datasets and analyzed the data using state of the art face classification techniques. The best performing classifier achieved the maximum rank-1 identification rate of 53.8%. We conclude that facial spectral reflectance alone is not a reliable biometric for unconstrained face recognition.

  16. Angle of arrival estimation using spectral interferometry

    International Nuclear Information System (INIS)

    Barber, Z.W.; Harrington, C.; Thiel, C.W.; Babbitt, W.R.; Krishna Mohan, R.

    2010-01-01

    We have developed a correlative signal processing concept based on a Mach-Zehnder interferometer and spatial-spectral (S2) materials that enables direct mapping of RF spectral phase as well as power spectral recording. This configuration can be used for precise frequency resolved time delay estimation between signals received by a phased antenna array system that in turn could be utilized to estimate the angle of arrival. We present an analytical theoretical model and a proof-of-principle demonstration of the concept of time difference of arrival estimation with a cryogenically cooled Tm:YAG crystal that operates on microwave signals modulated onto a stabilized optical carrier at 793 nm.

  17. Angle of arrival estimation using spectral interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Barber, Z.W.; Harrington, C.; Thiel, C.W.; Babbitt, W.R. [Spectrum Lab, Montana State University, Bozeman, MT 59717 (United States); Krishna Mohan, R., E-mail: krishna@spectrum.montana.ed [Spectrum Lab, Montana State University, Bozeman, MT 59717 (United States)

    2010-09-15

    We have developed a correlative signal processing concept based on a Mach-Zehnder interferometer and spatial-spectral (S2) materials that enables direct mapping of RF spectral phase as well as power spectral recording. This configuration can be used for precise frequency resolved time delay estimation between signals received by a phased antenna array system that in turn could be utilized to estimate the angle of arrival. We present an analytical theoretical model and a proof-of-principle demonstration of the concept of time difference of arrival estimation with a cryogenically cooled Tm:YAG crystal that operates on microwave signals modulated onto a stabilized optical carrier at 793 nm.

  18. KK -theory and spectral flow in von Neumann algebras

    DEFF Research Database (Denmark)

    Kaad, Jens; Nest, Ryszard; Rennie, Adam

    2012-01-01

    We present a definition of spectral flow for any norm closed ideal J in any von Neumann algebra N. Given a path of selfadjoint operators in N which are invertible in N/J, the spectral flow produces a class in Ko (J). Given a semifinite spectral triple (A, H, D) relative to (N, t) with A separable...

  19. Spectral colors capture and reproduction based on digital camera

    Science.gov (United States)

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

    2018-01-01

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

  20. Spectral Estimation of UV-Vis Absorbance Time Series for Water Quality Monitoring

    Directory of Open Access Journals (Sweden)

    Leonardo Plazas-Nossa

    2017-05-01

    Full Text Available Context: Signals recorded as multivariate time series by UV-Vis absorbance captors installed in urban sewer systems, can be non-stationary, yielding complications in the analysis of water quality monitoring. This work proposes to perform spectral estimation using the Box-Cox transformation and differentiation in order to obtain stationary multivariate time series in a wide sense. Additionally, Principal Component Analysis (PCA is applied to reduce their dimensionality. Method: Three different UV-Vis absorbance time series for different Colombian locations were studied: (i El-Salitre Wastewater Treatment Plant (WWTP in Bogotá; (ii Gibraltar Pumping Station (GPS in Bogotá; and (iii San-Fernando WWTP in Itagüí. Each UV-Vis absorbance time series had equal sample number (5705. The esti-mation of the spectral power density is obtained using the average of modified periodograms with rectangular window and an overlap of 50%, with the 20 most important harmonics from the Discrete Fourier Transform (DFT and Inverse Fast Fourier Transform (IFFT. Results: Absorbance time series dimensionality reduction using PCA, resulted in 6, 8 and 7 principal components for each study site respectively, altogether explaining more than 97% of their variability. Values of differences below 30% for the UV range were obtained for the three study sites, while for the visible range the maximum differences obtained were: (i 35% for El-Salitre WWTP; (ii 61% for GPS; and (iii 75% for San-Fernando WWTP. Conclusions: The Box-Cox transformation and the differentiation process applied to the UV-Vis absorbance time series for the study sites (El-Salitre, GPS and San-Fernando, allowed to reduce variance and to eliminate ten-dency of the time series. A pre-processing of UV-Vis absorbance time series is recommended to detect and remove outliers and then apply the proposed process for spectral estimation. Language: Spanish.

  1. Self-referencing, spectrally, or spatially encoded spectral interferometry for the complete characterization of attosecond electromagnetic pulses

    International Nuclear Information System (INIS)

    Cormier, Eric; Walmsley, Ian A.; Wyatt, Adam S.; Corner, Laura; Kosik, Ellen M.; DiMauro, Louis F.

    2005-01-01

    We propose a method for the complete characterization of attosecond duration electromagnetic pulses produced by high harmonic generation in an atomic gas. Our method is based on self-referencing spectral interferometry of two spectrally sheared extreme ultraviolet pulses, which is achieved by pumping the harmonic source with two sheared optical driving pulses. The resulting interferogram contains sufficient information to completely reconstruct the temporal behavior of the electric field. We demonstrate that such a method is feasible, and outline two possible experimental configurations

  2. The spectral dimension of random trees

    International Nuclear Information System (INIS)

    Destri, Claudio; Donetti, Luca

    2002-01-01

    We present a simple yet rigorous approach to the determination of the spectral dimension of random trees, based on the study of the massless limit of the Gaussian model on such trees. As a by-product, we obtain evidence in favour of a new scaling hypothesis for the Gaussian model on generic bounded graphs and in favour of a previously conjectured exact relation between spectral and connectivity dimensions on more general tree-like structures

  3. Heterodyne detection using spectral line pairing for spectral phase encoding optical code division multiple access and dynamic dispersion compensation.

    Science.gov (United States)

    Yang, Yi; Foster, Mark; Khurgin, Jacob B; Cooper, A Brinton

    2012-07-30

    A novel coherent optical code-division multiple access (OCDMA) scheme is proposed that uses spectral line pairing to generate signals suitable for heterodyne decoding. Both signal and local reference are transmitted via a single optical fiber and a simple balanced receiver performs sourceless heterodyne detection, canceling speckle noise and multiple-access interference (MAI). To validate the idea, a 16 user fully loaded phase encoded system is simulated. Effects of fiber dispersion on system performance are studied as well. Both second and third order dispersion management is achieved by using a spectral phase encoder to adjust phase shifts of spectral components at the optical network unit (ONU).

  4. Selective data reduction in gas chromatography/infrared spectrometry

    International Nuclear Information System (INIS)

    Pyo, Dong Jin; Shin, Hyun Du

    2001-01-01

    As gas chromatography/infrared spectrometry (GC/IR) becomes routinely available, methods must be developed to deal with the large amount of data produced. We demonstrate computer methods that quickly search through a large data file, locating those spectra that display a spectral feature of interest. Based on a modified library search routine, these selective data reduction methods retrieve all or nearly all of the compounds of interest, while rejection the vast majority of unrelated compounds. To overcome the shifting problem of IR spectra, a search method of moving the average pattern was designed. In this moving pattern search, the average pattern of a particular functional group was not held stationary, but was allowed to be moved a little bit right and left

  5. A divisive spectral method for network community detection

    International Nuclear Information System (INIS)

    Cheng, Jianjun; Li, Longjie; Yao, Yukai; Chen, Xiaoyun; Leng, Mingwei; Lu, Weiguo

    2016-01-01

    Community detection is a fundamental problem in the domain of complex network analysis. It has received great attention, and many community detection methods have been proposed in the last decade. In this paper, we propose a divisive spectral method for identifying community structures from networks which utilizes a sparsification operation to pre-process the networks first, and then uses a repeated bisection spectral algorithm to partition the networks into communities. The sparsification operation makes the community boundaries clearer and sharper, so that the repeated spectral bisection algorithm extract high-quality community structures accurately from the sparsified networks. Experiments show that the combination of network sparsification and a spectral bisection algorithm is highly successful, the proposed method is more effective in detecting community structures from networks than the others. (paper: interdisciplinary statistical mechanics)

  6. Hybrid spectral CT reconstruction.

    Directory of Open Access Journals (Sweden)

    Darin P Clark

    Full Text Available Current photon counting x-ray detector (PCD technology faces limitations associated with spectral fidelity and photon starvation. One strategy for addressing these limitations is to supplement PCD data with high-resolution, low-noise data acquired with an energy-integrating detector (EID. In this work, we propose an iterative, hybrid reconstruction technique which combines the spectral properties of PCD data with the resolution and signal-to-noise characteristics of EID data. Our hybrid reconstruction technique is based on an algebraic model of data fidelity which substitutes the EID data into the data fidelity term associated with the PCD reconstruction, resulting in a joint reconstruction problem. Within the split Bregman framework, these data fidelity constraints are minimized subject to additional constraints on spectral rank and on joint intensity-gradient sparsity measured between the reconstructions of the EID and PCD data. Following a derivation of the proposed technique, we apply it to the reconstruction of a digital phantom which contains realistic concentrations of iodine, barium, and calcium encountered in small-animal micro-CT. The results of this experiment suggest reliable separation and detection of iodine at concentrations ≥ 5 mg/ml and barium at concentrations ≥ 10 mg/ml in 2-mm features for EID and PCD data reconstructed with inherent spatial resolutions of 176 μm and 254 μm, respectively (point spread function, FWHM. Furthermore, hybrid reconstruction is demonstrated to enhance spatial resolution within material decomposition results and to improve low-contrast detectability by as much as 2.6 times relative to reconstruction with PCD data only. The parameters of the simulation experiment are based on an in vivo micro-CT experiment conducted in a mouse model of soft-tissue sarcoma. Material decomposition results produced from this in vivo data demonstrate the feasibility of distinguishing two K-edge contrast agents with

  7. Hybrid spectral CT reconstruction

    Science.gov (United States)

    Clark, Darin P.

    2017-01-01

    Current photon counting x-ray detector (PCD) technology faces limitations associated with spectral fidelity and photon starvation. One strategy for addressing these limitations is to supplement PCD data with high-resolution, low-noise data acquired with an energy-integrating detector (EID). In this work, we propose an iterative, hybrid reconstruction technique which combines the spectral properties of PCD data with the resolution and signal-to-noise characteristics of EID data. Our hybrid reconstruction technique is based on an algebraic model of data fidelity which substitutes the EID data into the data fidelity term associated with the PCD reconstruction, resulting in a joint reconstruction problem. Within the split Bregman framework, these data fidelity constraints are minimized subject to additional constraints on spectral rank and on joint intensity-gradient sparsity measured between the reconstructions of the EID and PCD data. Following a derivation of the proposed technique, we apply it to the reconstruction of a digital phantom which contains realistic concentrations of iodine, barium, and calcium encountered in small-animal micro-CT. The results of this experiment suggest reliable separation and detection of iodine at concentrations ≥ 5 mg/ml and barium at concentrations ≥ 10 mg/ml in 2-mm features for EID and PCD data reconstructed with inherent spatial resolutions of 176 μm and 254 μm, respectively (point spread function, FWHM). Furthermore, hybrid reconstruction is demonstrated to enhance spatial resolution within material decomposition results and to improve low-contrast detectability by as much as 2.6 times relative to reconstruction with PCD data only. The parameters of the simulation experiment are based on an in vivo micro-CT experiment conducted in a mouse model of soft-tissue sarcoma. Material decomposition results produced from this in vivo data demonstrate the feasibility of distinguishing two K-edge contrast agents with a spectral

  8. Synthesis and inversion of Stokes spectral profiles. Thesis

    International Nuclear Information System (INIS)

    Murphy, G.A.

    1990-01-01

    Observations of Stokes spectral profiles enable the magnetic fields on the Sun's surface to be determined. Inversion is the process whereby the profiles are reduced to magnetic field vectors. One of the most robust, accurate and rapid methods available for inversion uses the least-squares fitting of analytical Stokes profiles. As this technique is suitable for the automated reduction of large sets of data, it has been adopted for use with the Advanced Stokes Polarimeter, presently under development. The limitations of inversion by analytical profile fitting have not been firmly established. Confident analysis of magnet field vectors depends upon the precise interpretation of reduced data. In this work, a framework is introduced which allows such an assessment to be made. The magnetofluid-static sunspot models presented here provide a self-consistent range of physical conditions similar to those in sunspots. Inversion can then be carried out on Stokes profiles synthesized from these known realistic conditions. The capabilities of an inversion technique can be evaluated by comparison between the models and the deduced values

  9. Nightside studies of coherent HF Radar spectral width behaviour

    Directory of Open Access Journals (Sweden)

    E. E. Woodfield

    2002-09-01

    Full Text Available A previous case study found a relationship between high spectral width measured by the CUTLASS Finland HF radar and elevated electron temperatures observed by the EISCAT and ESR incoherent scatter radars in the post-midnight sector of magnetic local time. This paper expands that work by briefly re-examining that interval and looking in depth at two further case studies. In all three cases a region of high HF spectral width (>200 ms-1 exists poleward of a region of low HF spectral width (<200 ms-1. Each case, however, occurs under quite different geomagnetic conditions. The original case study occurred during an interval with no observed electrojet activity, the second study during a transition from quiet to active conditions with a clear band of ion frictional heating indicating the location of the flow reversal boundary, and the third during an isolated sub-storm. These case studies indicate that the relationship between elevated electron temperature and high HF radar spectral width appears on closed field lines after 03:00 magnetic local time (MLT on the nightside. It is not clear whether the same relationship would hold on open field lines, since our analysis of this relationship is restricted in latitude. We find two important properties of high spectral width data on the nightside. Firstly the high spectral width values occur on both open and closed field lines, and secondly that the power spectra which exhibit high widths are both single-peak and multiple-peak. In general the regions of high spectral width (>200 ms-1 have more multiple-peak spectra than the regions of low spectral widths whilst still maintaining a majority of single-peak spectra. We also find that the region of ion frictional heating is collocated with many multiple-peak HF spectra. Several mechanisms for the generation of high spectral width have been proposed which would produce multiple-peak spectra, these are discussed in relation to the data presented here. Since the

  10. Nightside studies of coherent HF Radar spectral width behaviour

    Directory of Open Access Journals (Sweden)

    E. E. Woodfield

    Full Text Available A previous case study found a relationship between high spectral width measured by the CUTLASS Finland HF radar and elevated electron temperatures observed by the EISCAT and ESR incoherent scatter radars in the post-midnight sector of magnetic local time. This paper expands that work by briefly re-examining that interval and looking in depth at two further case studies. In all three cases a region of high HF spectral width (>200 ms-1 exists poleward of a region of low HF spectral width (<200 ms-1. Each case, however, occurs under quite different geomagnetic conditions. The original case study occurred during an interval with no observed electrojet activity, the second study during a transition from quiet to active conditions with a clear band of ion frictional heating indicating the location of the flow reversal boundary, and the third during an isolated sub-storm. These case studies indicate that the relationship between elevated electron temperature and high HF radar spectral width appears on closed field lines after 03:00 magnetic local time (MLT on the nightside. It is not clear whether the same relationship would hold on open field lines, since our analysis of this relationship is restricted in latitude. We find two important properties of high spectral width data on the nightside. Firstly the high spectral width values occur on both open and closed field lines, and secondly that the power spectra which exhibit high widths are both single-peak and multiple-peak. In general the regions of high spectral width (>200 ms-1 have more multiple-peak spectra than the regions of low spectral widths whilst still maintaining a majority of single-peak spectra. We also find that the region of ion frictional heating is collocated with many multiple-peak HF spectra. Several mechanisms for the generation of high spectral width have been proposed which would produce multiple-peak spectra, these are discussed in relation to

  11. Explosion Amplitude Reduction due to Fractures in Water-Saturated and Dry Granite

    Science.gov (United States)

    Stroujkova, A. F.; Leidig, M.; Bonner, J. L.

    2013-12-01

    Empirical observations made at the Semipalatinsk Test Site suggest that nuclear tests in the fracture zones left by previous explosions ('repeat shots') show reduced seismic amplitudes compared to the nuclear tests in virgin rocks. Likely mechanisms for the amplitude reduction in the repeat shots include increased porosity and reduced strength and elastic moduli, leading to pore closing and frictional sliding. Presence of pore water significantly decreases rock compressibility and strength, thus affecting seismic amplitudes. A series of explosion experiments were conducted in order to define the physical mechanism responsible for the amplitude reduction and to quantify the degree of the amplitude reduction in fracture zones of previously detonated explosions. Explosions in water-saturated granite were conducted in central New Hampshire in 2011 and 2012. Additional explosions in dry granite were detonated in Barre, VT in 2013. The amplitude reduction is different between dry and water-saturated crystalline rocks. Significant reduction in seismic amplitudes (by a factor of 2-3) in water-saturated rocks was achieved only when the repeat shot was detonated in the extensive damage zone created by a significantly larger (by a factor of 5) explosion. In case where the first and the second explosions were similar in yield, the amplitude reduction was relatively modest (5-20%). In dry rocks the amplitude reduction reached a factor of 2 even in less extensive damage zones. In addition there are differences in frequency dependence of the spectral amplitude ratios between explosions in dry and water-saturated rocks. Thus the amplitude reduction is sensitive to the extent of the damage zone as well as the pore water content.

  12. Spectral interferometric length measurement and tomography

    International Nuclear Information System (INIS)

    Pinkl, W.

    1998-01-01

    This work presents a new method for optical length measurement using the principles of spectral interferometry. Results of thickness measurements on glass plates, the human cornea in vivo and human finger and toe nails in vivo and in vitro are discussed. It could be demonstrated that the absorption coefficient of red and green ink can be measured depth sensitive. Another chapter describes a new technique to measure a thickness profile of a sample within the illuminating beam. It could be demonstrated that a thickness profile over a distance of a few millimeters can be measured with one single measurement. At the Institute of Medical Physics of the University of Vienna a method to measure intraocular distances by the means of interferometry has been developed during the last ten years. Basing on this method (dual beam interferometry) an optical in vivo tomography experiment could be established. A thickness map of the retina of a human eye in vivo can be easily measured. The dual beam technique uses a Michelson interferometer with a moving mirror to adjust the length of the interferometer arms. The mirror is moved by a stepper motor. This movement induces vibrations, misalignment and other disadvantages. So mechanically moved parts as reasons for possible errors should be eliminated. This work shows one possible solution - using the principle of spectral interferometry. A spectral interferometry experiment is a static experiment, no moving parts are used. A spectral interferometry experiment has been used to measure the thickness of glass plates and stacks of glass plates. Using two light sources of different wavelengths spectral absorption properties of a sample can be measured depth sensitive. This could be demonstrated with stacks of glass plates and the use of red and green ink between two plates. The obtained results are compared to the results of a computer simulation. To demonstrate the ability of spectral interferometry to measure the thickness of biologic

  13. Particulate characterization by PIXE multivariate spectral analysis

    International Nuclear Information System (INIS)

    Antolak, Arlyn J.; Morse, Daniel H.; Grant, Patrick G.; Kotula, Paul G.; Doyle, Barney L.; Richardson, Charles B.

    2007-01-01

    Obtaining particulate compositional maps from scanned PIXE (proton-induced X-ray emission) measurements is extremely difficult due to the complexity of analyzing spectroscopic data collected with low signal-to-noise at each scan point (pixel). Multivariate spectral analysis has the potential to analyze such data sets by reducing the PIXE data to a limited number of physically realizable and easily interpretable components (that include both spectral and image information). We have adapted the AXSIA (automated expert spectral image analysis) program, originally developed by Sandia National Laboratories to quantify electron-excited X-ray spectroscopy data, for this purpose. Samples consisting of particulates with known compositions and sizes were loaded onto Mylar and paper filter substrates and analyzed by scanned micro-PIXE. The data sets were processed by AXSIA and the associated principal component spectral data were quantified by converting the weighting images into concentration maps. The results indicate automated, nonbiased, multivariate statistical analysis is useful for converting very large amounts of data into a smaller, more manageable number of compositional components needed for locating individual particles-of-interest on large area collection media

  14. Automatic spectral imaging protocol selection and iterative reconstruction in abdominal CT with reduced contrast agent dose: initial experience.

    Science.gov (United States)

    Lv, Peijie; Liu, Jie; Chai, Yaru; Yan, Xiaopeng; Gao, Jianbo; Dong, Junqiang

    2017-01-01

    To evaluate the feasibility, image quality, and radiation dose of automatic spectral imaging protocol selection (ASIS) and adaptive statistical iterative reconstruction (ASIR) with reduced contrast agent dose in abdominal multiphase CT. One hundred and sixty patients were randomly divided into two scan protocols (n = 80 each; protocol A, 120 kVp/450 mgI/kg, filtered back projection algorithm (FBP); protocol B, spectral CT imaging with ASIS and 40 to 70 keV monochromatic images generated per 300 mgI/kg, ASIR algorithm. Quantitative parameters (image noise and contrast-to-noise ratios [CNRs]) and qualitative visual parameters (image noise, small structures, organ enhancement, and overall image quality) were compared. Monochromatic images at 50 keV and 60 keV provided similar or lower image noise, but higher contrast and overall image quality as compared with 120-kVp images. Despite the higher image noise, 40-keV images showed similar overall image quality compared to 120-kVp images. Radiation dose did not differ between the two protocols, while contrast agent dose in protocol B was reduced by 33 %. Application of ASIR and ASIS to monochromatic imaging from 40 to 60 keV allowed contrast agent dose reduction with adequate image quality and without increasing radiation dose compared to 120 kVp with FBP. • Automatic spectral imaging protocol selection provides appropriate scan protocols. • Abdominal CT is feasible using spectral imaging and 300 mgI/kg contrast agent. • 50-keV monochromatic images with 50 % ASIR provide optimal image quality.

  15. Spectral correlations in Anderson insulating wires

    Science.gov (United States)

    Marinho, M.; Micklitz, T.

    2018-01-01

    We calculate the spectral level-level correlation function of Anderson insulating wires for all three Wigner-Dyson classes. A measurement of its Fourier transform, the spectral form factor, is within reach of state-of-the-art cold atom quantum quench experiments, and we find good agreement with recent numerical simulations of the latter. Our derivation builds on a representation of the level-level correlation function in terms of a local generating function which may prove useful in other contexts.

  16. Multi spectral scaling data acquisition system

    International Nuclear Information System (INIS)

    Behere, Anita; Patil, R.D.; Ghodgaonkar, M.D.; Gopalakrishnan, K.R.

    1997-01-01

    In nuclear spectroscopy applications, it is often desired to acquire data at high rate with high resolution. With the availability of low cost computers, it is possible to make a powerful data acquisition system with minimum hardware and software development, by designing a PC plug-in acquisition board. But in using the PC processor for data acquisition, the PC can not be used as a multitasking node. Keeping this in view, PC plug-in acquisition boards with on-board processor find tremendous applications. Transputer based data acquisition board has been designed which can be configured as a high count rate pulse height MCA or as a Multi Spectral Scaler. Multi Spectral Scaling (MSS) is a new technique, in which multiple spectra are acquired in small time frames and are then analyzed. This paper describes the details of this multi spectral scaling data acquisition system. 2 figs

  17. Archiving Spectral Libraries in the Planetary Data System

    Science.gov (United States)

    Slavney, S.; Guinness, E. A.; Scholes, D.; Zastrow, A.

    2017-12-01

    Spectral libraries are becoming popular candidates for archiving in PDS. With the increase in the number of individual investigators funded by programs such as NASA's PDART, the PDS Geosciences Node is receiving many requests for support from proposers wishing to archive various forms of laboratory spectra. To accommodate the need for a standardized approach to archiving spectra, the Geosciences Node has designed the PDS Spectral Library Data Dictionary, which contains PDS4 classes and attributes specifically for labeling spectral data, including a classification scheme for samples. The Reflectance Experiment Laboratory (RELAB) at Brown University, which has long been a provider of spectroscopy equipment and services to the science community, has provided expert input into the design of the dictionary. Together the Geosciences Node and RELAB are preparing the whole of the RELAB Spectral Library, consisting of many thousands of spectra collected over the years, to be archived in PDS. An online interface for searching, displaying, and downloading selected spectra is planned, using the Spectral Library metadata recorded in the PDS labels. The data dictionary and online interface will be extended to include spectral libraries submitted by other data providers. The Spectral Library Data Dictionary is now available from PDS at https://pds.nasa.gov/pds4/schema/released/. It can be used in PDS4 labels for reflectance spectra as well as for Raman, XRF, XRD, LIBS, and other types of spectra. Ancillary data such as images, chemistry, and abundance data are also supported. To help generate PDS4-compliant labels for spectra, the Geosciences Node provides a label generation program called MakeLabels (http://pds-geosciences.wustl.edu/tools/makelabels.html) which creates labels from a template, and which can be used for any kind of PDS4 label. For information, contact the Geosciences Node at geosci@wunder.wustl.edu.

  18. From dispersion relations to spectral dimension - and back again

    International Nuclear Information System (INIS)

    Sotiriou, Thomas P.; Visser, Matt; Weinfurtner, Silke

    2011-01-01

    The so-called spectral dimension is a scale-dependent number associated with both geometries and field theories that has recently attracted much attention, driven largely, though not exclusively, by investigations of causal dynamical triangulations and Horava gravity as possible candidates for quantum gravity. We advocate the use of the spectral dimension as a probe for the kinematics of these (and other) systems in the region where spacetime curvature is small, and the manifold is flat to a good approximation. In particular, we show how to assign a spectral dimension (as a function of so-called diffusion time) to any arbitrarily specified dispersion relation. We also analyze the fundamental properties of spectral dimension using extensions of the usual Seeley-DeWitt and Feynman expansions and by using saddle point techniques. The spectral dimension turns out to be a useful, robust, and powerful probe, not only of geometry, but also of kinematics.

  19. Spectral band discrimination for species observed from hyperspectral remote sensing

    CSIR Research Space (South Africa)

    Dudeni, N

    2009-08-01

    Full Text Available across the spectrum. Spectral matching is often achieved by means of matching algorithms such as the Spectral Angle Mapper (SAM), Spectral information divergence (SID) and mixed measures of SAM and SID using either the tangent or the sine trigonometric...

  20. On spectral resolutions of differential vector-operators

    International Nuclear Information System (INIS)

    Ashurov, R.R.; Sokolov, M.S.

    2004-04-01

    We show that spectral resolutions of differential vector-operators may be represented as a specific direct sum integral operator with a kernel written in terms of generalized vector-operator eigenfunctions. Then we prove that a generalized eigenfunction measurable with respect to the spectral parameter may be decomposed using a set of analytical defining systems of coordinate operators. (author)

  1. Hyperspectral image classifier based on beach spectral feature

    International Nuclear Information System (INIS)

    Liang, Zhang; Lianru, Gao; Bing, Zhang

    2014-01-01

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

  2. [Study on the arc spectral information for welding quality diagnosis].

    Science.gov (United States)

    Li, Zhi-Yong; Gu, Xiao-Yan; Li, Huan; Yang, Li-Jun

    2009-03-01

    Through collecting the spectral signals of TIG and MIG welding arc with spectrometer, the arc light radiations were analyzed based on the basic theory of plasma physics. The radiation of welding arc distributes over a broad range of frequency, from infrared to ultraviolet. The arc spectrum is composed of line spectra and continuous spectra. Due to the variation of metal density in the welding arc, there is great difference between the welding arc spectra of TIG and MIG in both their intensity and distribution. The MIG welding arc provides more line spectra of metal and the intensity of radiation is greater than TIG. The arc spectrum of TIG welding is stable during the welding process, disturbance factors that cause the spectral variations can be reflected by the spectral line related to the corresponding element entering the welding arc. The arc spectrum of MIG welding will fluctuate severely due to droplet transfer, which produces "noise" in the line spectrum aggregation zone. So for MIG welding, the spectral zone lacking spectral line is suitable for welding quality diagnosis. According to the characteristic of TIG and MIG, special spectral zones were selected for welding quality diagnosis. For TIG welding, the selected zone is in ultraviolet zone (230-300 nm). For MIG welding, the selected zone is in visible zone (570-590 nm). With the basic theory provided for welding quality diagnosis, the integral intensity of spectral signal in the selected zone of welding process with disturbing factor was studied to prove the theory. The results show that the welding quality and disturbance factors can be diagnosed with good signal to noise ratio in the selected spectral zone compared with signal in other spectral zone. The spectral signal can be used for real-time diagnosis of the welding quality.

  3. Spectral structure of mesoscale winds over the water

    DEFF Research Database (Denmark)

    Larsén, Xiaoli Guo; Vincent, Claire Louise; Larsen, Søren Ejling

    2013-01-01

    to describe the spectral slope transition as well as the limit for application of the Taylor hypothesis. The stability parameter calculated from point measurements, the bulk Richardson number, is found insufficient to represent the various atmospheric structures that have their own spectral behaviours under...... spectra show universal characteristics, in agreement with the findings in literature, including the energy amplitude and the −5/3 spectral slope in the mesoscale range transitioning to a slope of −3 for synoptic and planetary scales. The integral time-scale of the local weather is found to be useful...... different stability conditions, such as open cells and gravity waves. For stationary conditions, the mesoscale turbulence is found to bear some characteristics of two-dimensional isotropy, including (1) very minor vertical variation of spectra; (2) similar spectral behaviour for the along- and across...

  4. General spectral flow formula for fixed maximal domain

    DEFF Research Database (Denmark)

    Booss-Bavnbek, Bernhelm; Zhu, Chaofeng

    2005-01-01

    of the resulting continuous family of (unbounded) self-adjoint Fredholm operators in terms of the Maslov index of two related curves of Lagrangian spaces. One curve is given by the varying domains, the other by the Cauchy data spaces. We provide rigorous definitions of the underlying concepts of spectral theory......We consider a continuous curve of linear elliptic formally self-adjoint differential operators of first order with smooth coefficients over a compact Riemannian manifold with boundary together with a continuous curve of global elliptic boundary value problems. We express the spectral flow...... and symplectic analysis and give a full (and surprisingly short) proof of our General Spectral Flow Formula for the case of fixed maximal domain. As a side result, we establish local stability of weak inner unique continuation property (UCP) and explain its role for parameter dependent spectral theory....

  5. Spectral and spatial shaping of Smith-Purcell radiation

    Science.gov (United States)

    Remez, Roei; Shapira, Niv; Roques-Carmes, Charles; Tirole, Romain; Yang, Yi; Lereah, Yossi; Soljačić, Marin; Kaminer, Ido; Arie, Ady

    2017-12-01

    The Smith-Purcell effect, observed when an electron beam passes in the vicinity of a periodic structure, is a promising platform for the generation of electromagnetic radiation in previously unreachable spectral ranges. However, most of the studies of this radiation were performed on simple periodic gratings, whose radiation spectrum exhibits a single peak and its higher harmonics predicted by a well-established dispersion relation. Here, we propose a method to shape the spatial and spectral far-field distribution of the radiation using complex periodic and aperiodic gratings. We show, theoretically and experimentally, that engineering multiple peak spectra with controlled widths located at desired wavelengths is achievable using Smith-Purcell radiation. Our method opens the way to free-electron-driven sources with tailored angular and spectral responses, and gives rise to focusing functionality for spectral ranges where lenses are unavailable or inefficient.

  6. Characterization of Passive Spectral Regrowth in Radio Frequency Systems

    Science.gov (United States)

    2013-01-01

    as using RF absorber and Faraday cages around sensi- tive spots. To ensure maximum radiated isolation, each cable or component should be shielded...nonlinear effects of spectral-regrowth-generating phenomena on an RF signal. Detection of low-level passive spectral regrowth close in frequency to a...experimentally and analytically characterize the nonlinear effects of spectral- regrowth-generating phenomena on an RF signal. Detection of low-level passive

  7. On Pythagoras Theorem for Products of Spectral Triples

    Science.gov (United States)

    D'Andrea, Francesco; Martinetti, Pierre

    2013-05-01

    We discuss a version of Pythagoras theorem in noncommutative geometry. Usual Pythagoras theorem can be formulated in terms of Connes' distance, between pure states, in the product of commutative spectral triples. We investigate the generalization to both non-pure states and arbitrary spectral triples. We show that Pythagoras theorem is replaced by some Pythagoras inequalities, that we prove for the product of arbitrary (i.e. non-necessarily commutative) spectral triples, assuming only some unitality condition. We show that these inequalities are optimal, and we provide non-unital counter-examples inspired by K-homology.

  8. On spectral distribution of high dimensional covariation matrices

    DEFF Research Database (Denmark)

    Heinrich, Claudio; Podolskij, Mark

    In this paper we present the asymptotic theory for spectral distributions of high dimensional covariation matrices of Brownian diffusions. More specifically, we consider N-dimensional Itô integrals with time varying matrix-valued integrands. We observe n equidistant high frequency data points...... of the underlying Brownian diffusion and we assume that N/n -> c in (0,oo). We show that under a certain mixed spectral moment condition the spectral distribution of the empirical covariation matrix converges in distribution almost surely. Our proof relies on method of moments and applications of graph theory....

  9. Spectral entropy and haemodynamic response to surgery during ...

    African Journals Online (AJOL)

    Adele

    Spectral entropy and haemodynamic response to surgery during sevoflurane anaesthesia. Introduction. Apart from somatic responses, surgery also evokes autonomic responses, including haemodynamic responses. Spectral entropy has been validated as a means to monitor the hypnotic state during sevoflurane ...

  10. Spectral-luminosity evolution of active galactic nuclei (AGN)

    Science.gov (United States)

    Leiter, Darryl; Boldt, Elihu

    1992-01-01

    The origin of the cosmic X-ray and gamma-ray backgrounds is explained via the mechanism of AGN spectral-luminosity evolution. The spectral evolution of precursor active galaxies into AGN, and Newton-Raphson input and output parameters are discussed.

  11. Airborne spectral measurements of surface anisotropy during SCAR-B

    Science.gov (United States)

    Tsay, Si-Chee; King, Michael D.; Arnold, G. Thomas; Li, Jason Y.

    1998-12-01

    During the Smoke, Clouds, and Radiation-Brazil (SCAR-B) deployment, angular distributions of spectral reflectance for vegetated surfaces and smoke layers were measured using the scanning cloud absorption radiometer (CAR) mounted on the University of Washington C-131A research aircraft. The CAR contains 13 narrowband spectral channels between 0.3 and 2.3 μm with a 190° scan aperture (5° before zenith to 5° past nadir) and 1° instantaneous field of view. The bidirectional reflectance is obtained by flying a clockwise circular orbit above the surface, resulting in a ground track ˜3 km in diameter within about 2 min. Although the CAR measurements are contaminated by minor atmospheric effects, results show distinct spectral characteristics for various types of surfaces. Spectral bidirectional reflectances of three simple and well-defined surfaces are presented: cerrado (August 18, 1995) and dense forest (August 25, 1995), both measured in Brazil under nearly clear-sky conditions, and thick smoke layers over dense forest (September 6 and 11, 1995). The bidirectional reflectances of cerrado and dense forest revealed fairly symmetric patterns along the principal plane, with varying maximal strengths and widths spectrally in the backscattering direction. In the shortwave-infrared region the aerosol effect is very small due to low spectral optical depth. Also, these backscattering maxima can be seen on the bidirectional reflectance of smoke layer over dense forest. These detailed measurements of the angular distribution of spectral reflectance can be parameterized by a few independent variables and utilized to retrieve either surface characteristics or aerosol microphysical and optical properties (e.g., size distribution and single-scattering parameters), if proper physical and radiation models are used. The spectral-hemispherical albedo of these surfaces is obtained directly by integrating all angular measurements and is compared with the measured nadir reflectance

  12. SPECTRAL FILTRATION OF IMAGES BY MEANS OF DISPERSIVE SYSTEMS

    Directory of Open Access Journals (Sweden)

    I. M. Gulis

    2016-01-01

    Full Text Available Instruments for spectral filtration of images are an important element of the systems used in remote sensing, medical diagnostics, in-process measurements. The aim of this study is analysis of the functional features and characteristics of the proposed two image monochromator versions which are based on dispersive spectral filtering. The first is based on the use of a dispersive monochromator, where collimating and camera lenses form a telescopic system, the dispersive element of which is within the intermediate image plane. The second version is based on an imaging double monochromator with dispersion subtraction by back propagation. For the telescopic system version, the spectral and spatial resolutions are estimated, the latter being limited by aberrations and diffraction from the entrance slit. The device has been numerically simulated and prototyped. It is shown that for the spectral bandwidth 10 nm (visible spectral range, the aberration-limited spot size is from 10–20 μm at the image center to about 30 μm at the image periphery for the image size 23–27 mm. The monochromator with dispersion subtraction enables one to vary the spectral resolution (up to 1 nm and higher by changing the intermediate slit width. But the distinctive feature is a significant change in the selected central wavelength over the image field. The considered designs of dispersive image monochromators look very promising due to the particular advantages over the systems based on tunable filters as regards the spectral resolution, fast tuning, and the spectral contrast. The monochromator based on a telescopic system has a simple design and a rather large image field but it also has a limited light throughput due to small aperture size. The monochromator with dispersion subtraction has higher light throughput, can provide high spectral resolution when recording a full data cube in a series of measuring acts for different dispersive element positions. 

  13. Interferometric filters for spectral discrimination in high-spectral-resolution lidar: performance comparisons between Fabry-Perot interferometer and field-widened Michelson interferometer.

    Science.gov (United States)

    Cheng, Zhongtao; Liu, Dong; Yang, Yongying; Yang, Liming; Huang, Hanlu

    2013-11-10

    Thanks to wavelength flexibility, interferometric filters such as Fabry-Perot interferometers (FPIs) and field-widened Michelson interferometers (FWMIs) have shown great convenience for spectrally separating the molecule and aerosol scattering components in the high-spectral-resolution lidar (HSRL) return signal. In this paper, performance comparisons between the FPI and FWMI as a spectroscopic discrimination filter in HSRL are performed. We first present a theoretical method for spectral transmission analysis and quantitative evaluation on the spectral discrimination. Then the process in determining the parameters of the FPI and FWMI for the performance comparisons is described. The influences from the incident field of view (FOV), the cumulative wavefront error induced by practical imperfections, and the frequency locking error on the spectral discrimination performance of the two filters are discussed in detail. Quantitative analyses demonstrate that FPI can produce higher transmittance while the remarkable spectral discrimination is one of the most appealing advantages of FWMI. As a result of the field-widened design, the FWMI still performs well even under the illumination with large FOV while the FPI is only qualified for a small incident angle. The cumulative wavefront error attaches a great effect on the spectral discrimination performance of the interferometric filters. We suggest if a cumulative wavefront error is less than 0.05 waves RMS, it is beneficial to employ the FWMI; otherwise, FPI may be more proper. Although the FWMI shows much more sensitivity to the frequency locking error, it can outperform the FPI given a locking error less than 0.1 GHz is achieved. In summary, the FWMI is very competent in HSRL applications if these practical engineering and control problems can be solved, theoretically. Some other estimations neglected in this paper can also be carried out through the analytical method illustrated herein.

  14. Spectral asymmetry for bag boundary conditions

    International Nuclear Information System (INIS)

    Beneventano, C G; Santangelo, E M; Wipf, A

    2002-01-01

    We give an expression, in terms of boundary spectral functions, for the spectral asymmetry of the Euclidean Dirac operator in two dimensions, when its domain is determined by local boundary conditions and the manifold is of product type. As an application, we explicitly evaluate the asymmetry in the case of a finite-length cylinder and check that the outcome is consistent with our general result. Finally, we study the asymmetry in a disc, which is a non-product case, and propose an interpretation

  15. Establishment and correction of an Echelle cross-prism spectrogram reduction model

    Science.gov (United States)

    Zhang, Rui; Bayanheshig; Li, Xiaotian; Cui, Jicheng

    2017-11-01

    The accuracy of an echelle cross-prism spectrometer depends on the matching degree between the spectrum reduction model and the actual state of the spectrometer. However, the error of adjustment can change the actual state of the spectrometer and result in a reduction model that does not match. This produces an inaccurate wavelength calibration. Therefore, the calibration of a spectrogram reduction model is important for the analysis of any echelle cross-prism spectrometer. In this study, the spectrogram reduction model of an echelle cross-prism spectrometer was established. The image position laws of a spectrometer that varies with the system parameters were simulated to the influence of the changes in prism refractive index, focal length and so on, on the calculation results. The model was divided into different wavebands. The iterative method, least squares principle and element lamps with known characteristic wavelength were used to calibrate the spectral model in different wavebands to obtain the actual values of the system parameters. After correction, the deviation of actual x- and y-coordinates and the coordinates calculated by the model are less than one pixel. The model corrected by this method thus reflects the system parameters in the current spectrometer state and can assist in accurate wavelength extraction. The instrument installation and adjustment would be guided in model-repeated correction, reducing difficulty of equipment, respectively.

  16. 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)

  17. Basic Functional Analysis Puzzles of Spectral Flow

    DEFF Research Database (Denmark)

    Booss-Bavnbek, Bernhelm

    2011-01-01

    We explain an array of basic functional analysis puzzles on the way to general spectral flow formulae and indicate a direction of future topological research for dealing with these puzzles.......We explain an array of basic functional analysis puzzles on the way to general spectral flow formulae and indicate a direction of future topological research for dealing with these puzzles....

  18. Time-resolved spectral measurements above 80 A

    International Nuclear Information System (INIS)

    Kauffman, R.L.; Ceglio, N.; Medecki, H.

    1983-01-01

    We have made time-resolved spectral measurements above 80 A from laser-produced plasmas. These are made using a transmission grating spectrograph whose primary components are a cylindrically-curved x-ray mirror for light collection, a transmission grating for spectral dispersions, and an x-ray streak camera for temporal resolution. A description of the instrument and an example of the data are given

  19. Spectral functions of hadrons in lattice QCD

    International Nuclear Information System (INIS)

    Nakahara, Y.; Asakawa, M.; Hatsuda, T.

    2000-01-01

    Using the maximum entropy method, spectral functions of the pseudo-scalar and vector mesons are extracted from lattice Monte Carlo data of the imaginary time Green's functions. The resonance and continuum structures as well as the ground state peaks are successfully obtained. Error analysis of the resultant spectral functions is also given on the basis of the Bayes probability theory. (author)

  20. Hadronic spectral functions in nuclear matter

    International Nuclear Information System (INIS)

    Post, M.; Leupold, S.; Mosel, U.

    2004-01-01

    We study the in-medium properties of mesons (π,η,ρ) and baryon resonances in cold nuclear matter within a coupled-channel analysis. The meson self energies are generated by particle-hole excitations. Thus multi-peak spectra are obtained for the mesonic spectral functions. In turn this leads to medium-modifications of the baryon resonances. Special care is taken to respect the analyticity of the spectral functions and to take into account effects from short-range correlations both for positive and negative parity states. Our model produces sensible results for pion and Δ dynamics in nuclear matter. We find a strong interplay of the ρ meson and the D 13 (1520), which moves spectral strength of the ρ spectrum to smaller invariant masses and leads to a broadening of the baryon resonance. The optical potential for the η meson resulting from our model is rather attractive whereas the in-medium properties modifications of the S 11 (1535) are found to be quite small

  1. Characterization of stochastic spatially and spectrally partially coherent electromagnetic pulsed beams

    International Nuclear Information System (INIS)

    Ding Chaoliang; Lue Baida; Pan Liuzhan

    2009-01-01

    The unified theory of coherence and polarization proposed by Wolf is extended from stochastic stationary electromagnetic beams to stochastic spatially and spectrally partially coherent electromagnetic pulsed beams. Taking the stochastic electromagnetic Gaussian Schell-model pulsed (GSMP) beam as a typical example of stochastic spatially and spectrally partially coherent electromagnetic pulsed beams, the expressions for the spectral density, spectral degree of polarization and spectral degree of coherence of stochastic electromagnetic GSMP beams propagating in free space are derived. Some special cases are analyzed. The illustrative examples are given and the results are interpreted physically.

  2. Spectral theorem in noncommutative field theories: Jacobi dynamics

    International Nuclear Information System (INIS)

    Géré, Antoine; Wallet, Jean-Christophe

    2015-01-01

    Jacobi operators appear as kinetic operators of several classes of noncommutative field theories (NCFT) considered recently. This paper deals with the case of bounded Jacobi operators. A set of tools mainly issued from operator and spectral theory is given in a way applicable to the study of NCFT. As an illustration, this is applied to a gauge-fixed version of the induced gauge theory on the Moyal plane expanded around a symmetric vacuum. The characterization of the spectrum of the kinetic operator is given, showing a behavior somewhat similar to a massless theory. An attempt to characterize the noncommutative geometry related to the gauge fixed action is presented. Using a Dirac operator obtained from the kinetic operator, it is shown that one can construct an even, regular, weakly real spectral triple. This spectral triple does not define a noncommutative metric space for the Connes spectral distance. (paper)

  3. Chebyshev super spectral viscosity method for water hammer analysis

    Directory of Open Access Journals (Sweden)

    Hongyu Chen

    2013-09-01

    Full Text Available In this paper, a new fast and efficient algorithm, Chebyshev super spectral viscosity (SSV method, is introduced to solve the water hammer equations. Compared with standard spectral method, the method's advantage essentially consists in adding a super spectral viscosity to the equations for the high wave numbers of the numerical solution. It can stabilize the numerical oscillation (Gibbs phenomenon and improve the computational efficiency while discontinuities appear in the solution. Results obtained from the Chebyshev super spectral viscosity method exhibit greater consistency with conventional water hammer calculations. It shows that this new numerical method offers an alternative way to investigate the behavior of the water hammer in propellant pipelines.

  4. Experimental Monitoring of Cr(VI) Bio-reduction Using Electrochemical Geophysics

    International Nuclear Information System (INIS)

    Birsen Canan; Gary R. Olhoeft; William A. Smith

    2007-01-01

    Many Department of Energy (DOE) sites are contaminated with highly carcinogenic hexavalent chromium (Cr(VI)). In this research, we explore the feasibility of applying complex resistivity to the detection and monitoring of microbially-induced reduction of hexavalent chromium (Cr(VI)) to a less toxic form (Cr(III)). We hope to measure the change in ionic concentration that occurs during this reduction reaction. This form of reduction promises to be an attractive alternative to more expensive remedial treatment methods. The specific goal of this research is to define the minimum and maximum concentration of the chemical and biological compounds in contaminated samples for which the Cr(VI) - Cr(III) reduction processes could be detected via complex resistivity. There are three sets of experiments, each comprised of three sample columns. The first experiment compares three concentrations of Cr(VI) at the same bacterial cell concentration. The second experiment establishes background samples with, and without, Cr(VI) and bacterial cells. The third experiment examines the influence of three different bacterial cell counts on the same concentration of Cr(VI). A polarization relaxation mechanism was observed between 10 and 50 Hz. The polarization mechanism, unfortunately, was not unique to bio-chemically active samples. Spectral analysis of complex resistivity data, however, showed that the frequency where the phase minimum occurred was not constant for bio-chemically active samples throughout the experiment. A significant shifts in phase minima occurred between 10 to 20 Hz from the initiation to completion of Cr(VI) reduction. This phenomena was quantified using the Cole-Cole model and the Marquardt-Levenberg nonlinear least square minimization method. The data suggests that the relaxation time and the time constant of this relaxation are the Cole-Cole parameters most sensitive to changes in biologically-induced reduction of Cr(VI)

  5. Comparisons of spectrally-enhanced asymmetrically-clipped optical OFDM systems.

    Science.gov (United States)

    Lowery, Arthur James

    2016-02-22

    Asymmetrically clipped optical orthogonal frequency-division multiplexing (ACO-OFDM) is a technique that sacrifices spectral efficiency in order to transmit an orthogonally frequency-division multiplexed signal over a unipolar channel, such as a directly modulated direct-detection fiber or free-space channel. Several methods have been proposed to regain this spectral efficiency, including: asymmetrically clipped DC-biased optical OFDM (ADO-OFDM), enhanced U-OFDM (EU-OFDM), spectral and energy efficient OFDM (SEE-OFDM), Hybrid-ACO-OFDM and Layered-ACO-OFDM. This paper presents simulations up to high-order constellation sizes to show that Layered-ACO-OFDM offers the highest receiver sensitivity for a given optical power at spectral efficiencies above 3 bit/s/Hz. For comparison purposes, white Gaussian noise is added at the receiver, component nonlinearities are not considered, and the fiber is considered to be linear and dispersion-less. The simulations show that LACO-OFDM has a 7-dB sensitivity advantage over DC-biased OFDM (DCO-OFDM) for 1024-QAM at 87.5% of DCO-OFDM's spectral efficiency, at the same bit rate and optical power. This is approximately equivalent to a 4.4-dB advantage at the same spectral efficiency of 87.7% if 896-QAM were to be used for DCO-OFDM.

  6. An evaluation of three commercially available metal artifact reduction methods for CT imaging

    International Nuclear Information System (INIS)

    Huang, Jessie Y; Kerns, James R; Balter, Peter A; Followill, David S; Mirkovic, Dragan; Howell, Rebecca M; Kry, Stephen F; Nute, Jessica L; Liu, Xinming; Stingo, Francesco C

    2015-01-01

    Three commercial metal artifact reduction methods were evaluated for use in computed tomography (CT) imaging in the presence of clinically realistic metal implants: Philips O-MAR, GE’s monochromatic gemstone spectral imaging (GSI) using dual-energy CT, and GSI monochromatic imaging with metal artifact reduction software applied (MARs). Each method was evaluated according to CT number accuracy, metal size accuracy, and streak artifact severity reduction by using several phantoms, including three anthropomorphic phantoms containing metal implants (hip prosthesis, dental fillings and spinal fixation rods). All three methods showed varying degrees of success for the hip prosthesis and spinal fixation rod cases, while none were particularly beneficial for dental artifacts. Limitations of the methods were also observed. MARs underestimated the size of metal implants and introduced new artifacts in imaging planes beyond the metal implant when applied to dental artifacts, and both the O-MAR and MARs algorithms induced artifacts for spinal fixation rods in a thoracic phantom. Our findings suggest that all three artifact mitigation methods may benefit patients with metal implants, though they should be used with caution in certain scenarios. (paper)

  7. Rapid spectral and flux time variations in a solar burst observed at various dm-mm wavelengths and at hard x rays

    International Nuclear Information System (INIS)

    Zodivaz, A.M.; Kaufmann, P.; Correia, E.; Costa, J.E.R.; Takakura, T.; Cliver, E.W.; Tapping, K.F.; Air Force Geophysics Lab., Hanscom AFB, MA; National Research Council of Canada, Ottawa, Ontario)

    1986-01-01

    A solar burst was observed with high sensitivity and time resolution at cm-mm wavelengths by two different radio observatories (Itapetinga and Algonquin), with high spectral time resolution at dm-mm wavelengths by patrol instruments (Sagamore Hill), and at hard x rays (HXM Hinotori). At the onset of the major burst time structure there was a rapid rise in the spectral turnover frequency (from 5 to 15 GHz), in about 10s, coincident to a reduction of the spectral index in the optically thin part of the spectrum. The burst maxima were not time coincident at the optically thin radio frequencies and at the different hard x ray energy ranges. The profiles at higher radio frequencies exhibited better time coincidence to the high energy x rays. The hardest x ray spectrum (-3) coincided with peak radio emission at the higher frequency (44 GHz). The event appeared to be built up by a first major injection of softer particles followed by other injections of harder particles. Ultrafast time structures were identified as superimposed on the burst emission at the cm-mm high sensitivity data at x rays, with predominant repetition rates ranging from 2.0 to 3.5 Hz

  8. Logarithmic compression methods for spectral data

    Science.gov (United States)

    Dunham, Mark E.

    2003-01-01

    A method is provided for logarithmic compression, transmission, and expansion of spectral data. A log Gabor transformation is made of incoming time series data to output spectral phase and logarithmic magnitude values. The output phase and logarithmic magnitude values are compressed by selecting only magnitude values above a selected threshold and corresponding phase values to transmit compressed phase and logarithmic magnitude values. A reverse log Gabor transformation is then performed on the transmitted phase and logarithmic magnitude values to output transmitted time series data to a user.

  9. Spectrally interleaved, comb-mode-resolved spectroscopy using swept dual terahertz combs.

    Science.gov (United States)

    Hsieh, Yi-Da; Iyonaga, Yuki; Sakaguchi, Yoshiyuki; Yokoyama, Shuko; Inaba, Hajime; Minoshima, Kaoru; Hindle, Francis; Araki, Tsutomu; Yasui, Takeshi

    2014-01-22

    Optical frequency combs are innovative tools for broadband spectroscopy because a series of comb modes can serve as frequency markers that are traceable to a microwave frequency standard. However, a mode distribution that is too discrete limits the spectral sampling interval to the mode frequency spacing even though individual mode linewidth is sufficiently narrow. Here, using a combination of a spectral interleaving and dual-comb spectroscopy in the terahertz (THz) region, we achieved a spectral sampling interval equal to the mode linewidth rather than the mode spacing. The spectrally interleaved THz comb was realized by sweeping the laser repetition frequency and interleaving additional frequency marks. In low-pressure gas spectroscopy, we achieved an improved spectral sampling density of 2.5 MHz and enhanced spectral accuracy of 8.39 × 10(-7) in the THz region. The proposed method is a powerful tool for simultaneously achieving high resolution, high accuracy, and broad spectral coverage in THz spectroscopy.

  10. Spectrally interleaved, comb-mode-resolved spectroscopy using swept dual terahertz combs

    Science.gov (United States)

    Hsieh, Yi-Da; Iyonaga, Yuki; Sakaguchi, Yoshiyuki; Yokoyama, Shuko; Inaba, Hajime; Minoshima, Kaoru; Hindle, Francis; Araki, Tsutomu; Yasui, Takeshi

    2014-01-01

    Optical frequency combs are innovative tools for broadband spectroscopy because a series of comb modes can serve as frequency markers that are traceable to a microwave frequency standard. However, a mode distribution that is too discrete limits the spectral sampling interval to the mode frequency spacing even though individual mode linewidth is sufficiently narrow. Here, using a combination of a spectral interleaving and dual-comb spectroscopy in the terahertz (THz) region, we achieved a spectral sampling interval equal to the mode linewidth rather than the mode spacing. The spectrally interleaved THz comb was realized by sweeping the laser repetition frequency and interleaving additional frequency marks. In low-pressure gas spectroscopy, we achieved an improved spectral sampling density of 2.5 MHz and enhanced spectral accuracy of 8.39 × 10-7 in the THz region. The proposed method is a powerful tool for simultaneously achieving high resolution, high accuracy, and broad spectral coverage in THz spectroscopy.

  11. Effective Spectral Function for Quasielastic Scattering on Nuclei

    OpenAIRE

    Bodek, A.; Christy, M. E.; Coopersmith, B.

    2014-01-01

    Spectral functions that are used in neutrino event generators to model quasielastic (QE) scattering from nuclear targets include Fermi gas, Local Thomas Fermi gas (LTF), Bodek-Ritchie Fermi gas with high momentum tail, and the Benhar-Fantoni two dimensional spectral function. We find that the $\

  12. The X-shooter Spectral Library and Carbon stars

    NARCIS (Netherlands)

    Gonneau, A.; Lançon, A.; Trager, S. C.; Chen, Y.; Peletier, R.; Aringer, B.; Nowotny, W.; Cambrésy, L.; Martins, F.; Nuss, E.; Palacios, A.

    2013-01-01

    Until recently, most empirical stellar spectral libraries were limited to a certain wavelength range or combined data from different stars, taken by different instruments of which some have low spectral resolution, limiting for instance our ability to analyze galaxies jointly in the ultraviolet, the

  13. Spectral partitioning and swells in the black sea

    NARCIS (Netherlands)

    van Vledder, G.P.; Akpınar, Adem; Lynett, P.

    2016-01-01

    The swell climate of the Black Sea has been determined using a long-term 31-year wave hindcast with the thirdgeneration spectral wave model SWAN in combination with spectral partitioning. This technique enables decomposing wave spectra into individual wave systems representing wind seas or swells

  14. PARALLEL SPATIOTEMPORAL SPECTRAL CLUSTERING WITH MASSIVE TRAJECTORY DATA

    Directory of Open Access Journals (Sweden)

    Y. Z. Gu

    2017-09-01

    Full Text Available Massive trajectory data contains wealth useful information and knowledge. Spectral clustering, which has been shown to be effective in finding clusters, becomes an important clustering approaches in the trajectory data mining. However, the traditional spectral clustering lacks the temporal expansion on the algorithm and limited in its applicability to large-scale problems due to its high computational complexity. This paper presents a parallel spatiotemporal spectral clustering based on multiple acceleration solutions to make the algorithm more effective and efficient, the performance is proved due to the experiment carried out on the massive taxi trajectory dataset in Wuhan city, China.

  15. General spectral flow formula for fixed maximal domain

    DEFF Research Database (Denmark)

    Booss-Bavnbek, Bernhelm; Zhu, Chaofeng

    2005-01-01

    and symplectic analysis and give a full (and surprisingly short) proof of our General Spectral Flow Formula for the case of fixed maximal domain. As a side result, we establish local stability of weak inner unique continuation property (UCP) and explain its role for parameter dependent spectral theory....... of the resulting continuous family of (unbounded) self-adjoint Fredholm operators in terms of the Maslov index of two related curves of Lagrangian spaces. One curve is given by the varying domains, the other by the Cauchy data spaces. We provide rigorous definitions of the underlying concepts of spectral theory...

  16. Spectral long-range interaction of temporal incoherent solitons.

    Science.gov (United States)

    Xu, Gang; Garnier, Josselin; Picozzi, Antonio

    2014-02-01

    We study the interaction of temporal incoherent solitons sustained by a highly noninstantaneous (Raman-like) nonlinear response. The incoherent solitons exhibit a nonmutual interaction, which can be either attractive or repulsive depending on their relative initial distance. The analysis reveals that incoherent solitons exhibit a long-range interaction in frequency space, which is in contrast with the expected spectral short-range interaction described by the usual approach based on the Raman-like spectral gain curve. Both phenomena of anomalous interaction and spectral long-range behavior of incoherent solitons are described in detail by a long-range Vlasov equation.

  17. Estimates of leaf area index from spectral reflectance of wheat under different cultural practices and solar angle

    Science.gov (United States)

    Asrar, G.; Kanemasu, E. T.; Yoshida, M.

    1985-01-01

    The influence of management practices and solar illumination angle on the leaf area index (LAI) was estimated from measurements of wheat canopy reflectance evaluated by two methods, a regression formula and an indirect technique. The date of planting and the time of irrigation in relation to the stage of plant growth were found to have significant effects on the development of leaves in spring wheat. A reduction in soil moisture adversely affected both the duration and magnitude of the maximum LAI for late planting dates. In general, water stress during vegetative stages resulted in a reduction in maximum LAI, while water stress during the reproductive period shortened the duration of green LAI in spring wheat. Canopy geometry and solar angle also affected the spectral properties of the canopies, and hence the estimated LAI. Increase in solar zenith angles resulted in a general increase in estimated LAI obtained from both methods.

  18. Recent progress of push-broom infrared hyper-spectral imager in SITP

    Science.gov (United States)

    Wang, Yueming; Hu, Weida; Shu, Rong; Li, Chunlai; Yuan, Liyin; Wang, Jianyu

    2017-02-01

    In the past decades, hyper-spectral imaging technologies were well developed in SITP, CAS. Many innovations for system design and key parts of hyper-spectral imager were finished. First airborne hyper-spectral imager operating from VNIR to TIR in the world was emerged in SITP. It is well known as OMIS(Operational Modular Imaging Spectrometer). Some new technologies were introduced to improve the performance of hyper-spectral imaging system in these years. A high spatial space-borne hyper-spectral imager aboard Tiangong-1 spacecraft was launched on Sep.29, 2011. Thanks for ground motion compensation and high optical efficiency prismatic spectrometer, a large amount of hyper-spectral imagery with high sensitivity and good quality were acquired in the past years. Some important phenomena were observed. To diminish spectral distortion and expand field of view, new type of prismatic imaging spectrometer based curved prism were proposed by SITP. A prototype of hyper-spectral imager based spherical fused silica prism were manufactured, which can operate from 400nm 2500nm. We also made progress in the development of LWIR hyper-spectral imaging technology. Compact and low F number LWIR imaging spectrometer was designed, manufactured and integrated. The spectrometer operated in a cryogenically-cooled vacuum box for background radiation restraint. The system performed well during flight experiment in an airborne platform. Thanks high sensitivity FPA and high performance optics, spatial resolution and spectral resolution and SNR of system are improved enormously. However, more work should be done for high radiometric accuracy in the future.

  19. Photoreceptor spectral sensitivity in the bumblebee, Bombus impatiens (Hymenoptera: Apidae.

    Directory of Open Access Journals (Sweden)

    Peter Skorupski

    Full Text Available The bumblebee Bombus impatiens is increasingly used as a model in comparative studies of colour vision, or in behavioural studies relying on perceptual discrimination of colour. However, full spectral sensitivity data on the photoreceptor inputs underlying colour vision are not available for B. impatiens. Since most known bee species are trichromatic, with photoreceptor spectral sensitivity peaks in the UV, blue and green regions of the spectrum, data from a related species, where spectral sensitivity measurements have been made, are often applied to B impatiens. Nevertheless, species differences in spectral tuning of equivalent photoreceptor classes may result in peaks that differ by several nm, which may have small but significant effects on colour discrimination ability. We therefore used intracellular recording to measure photoreceptor spectral sensitivity in B. impatiens. Spectral peaks were estimated at 347, 424 and 539 nm for UV, blue and green receptors, respectively, suggesting that this species is a UV-blue-green trichromat. Photoreceptor spectral sensitivity peaks are similar to previous measurements from Bombus terrestris, although there is a significant difference in the peak sensitivity of the blue receptor, which is shifted in the short wave direction by 12-13 nm in B. impatiens compared to B. terrestris.

  20. The broadband spectral energy distributions of SDSS blazars

    Science.gov (United States)

    Li, Huai-Zhen; Chen, Luo-En; Jiang, Yun-Guo; Yi, Ting-Feng

    2015-07-01

    We compiled the radio, optical and X-ray data of blazars from the Sloan Digital Sky Survey database, and presented the distribution of luminosities and broadband spectral indices. The distribution of luminosities shows that the averaged luminosity of flat spectrum radio quasars (FSRQs) is larger than that of BL Lacertae (BL Lac) objects. On the other hand, the broadband spectral energy distribution reveals that FSRQs and low energy peaked BL Lac objects have similar spectral properties, but high energy peaked BL Lac objects have a distinct spectral property. This may be due to the fact that different subclasses of blazars have different intrinsic environments and are at different cooling levels. Even so, a unified scheme is also revealed from the color-color diagram, which hints that there are similar physical processes operating in all objects under a range of intrinsic physical conditions or beaming parameters. Supported by the National Natural Science Foundation of China.

  1. Ultra-wideband spectral analysis using S2 technology

    International Nuclear Information System (INIS)

    Krishna Mohan, R.; Chang, T.; Tian, M.; Bekker, S.; Olson, A.; Ostrander, C.; Khallaayoun, A.; Dollinger, C.; Babbitt, W.R.; Cole, Z.; Reibel, R.R.; Merkel, K.D.; Sun, Y.; Cone, R.; Schlottau, F.; Wagner, K.H.

    2007-01-01

    This paper outlines the efforts to develop an ultra-wideband spectrum analyzer that takes advantage of the broad spectral response and fine spectral resolution (∼25 kHz) of spatial-spectral (S2) materials. The S2 material can process the full spectrum of broadband microwave transmissions, with adjustable time apertures (down to 100 μs) and fast update rates (up to 1 kHz). A cryogenically cooled Tm:YAG crystal that operates on microwave signals modulated onto a stabilized optical carrier at 793 nm is used as the core for the spectrum analyzer. Efforts to develop novel component technologies that enhance the performance of the system and meet the application requirements are discussed, including an end-to-end device model for parameter optimization. We discuss the characterization of new ultra-wide bandwidth S2 materials. Detection and post-processing module development including the implementation of a novel spectral recovery algorithm using field programmable gate array technology (FPGA) is also discussed

  2. Ultra-wideband spectral analysis using S2 technology

    Energy Technology Data Exchange (ETDEWEB)

    Krishna Mohan, R. [Spectrum Lab, Montana State University, Bozeman, MT 59717 (United States)]. E-mail: krishna@spectrum.montana.edu; Chang, T. [Spectrum Lab, Montana State University, Bozeman, MT 59717 (United States); Tian, M. [Spectrum Lab, Montana State University, Bozeman, MT 59717 (United States); Department of Physics, Montana State University, Bozeman, MT 59717 (United States); Bekker, S. [Spectrum Lab, Montana State University, Bozeman, MT 59717 (United States); Olson, A. [Spectrum Lab, Montana State University, Bozeman, MT 59717 (United States); Ostrander, C. [Spectrum Lab, Montana State University, Bozeman, MT 59717 (United States); Khallaayoun, A. [Spectrum Lab, Montana State University, Bozeman, MT 59717 (United States); Dollinger, C. [Spectrum Lab, Montana State University, Bozeman, MT 59717 (United States); Babbitt, W.R. [Spectrum Lab, Montana State University, Bozeman, MT 59717 (United States); Department of Physics, Montana State University, Bozeman, MT 59717 (United States); Cole, Z. [Spectrum Lab, Montana State University, Bozeman, MT 59717 (United States); S2 Corporation, Bozeman, MT 59718 (United States); Reibel, R.R. [Spectrum Lab, Montana State University, Bozeman, MT 59717 (United States); S2 Corporation, Bozeman, MT 59718 (United States); Merkel, K.D. [Spectrum Lab, Montana State University, Bozeman, MT 59717 (United States); S2 Corporation, Bozeman, MT 59718 (United States); Sun, Y. [Department of Physics, Montana State University, Bozeman, MT 59717 (United States); Cone, R. [Department of Physics, Montana State University, Bozeman, MT 59717 (United States); Schlottau, F. [University of Colorado, Boulder, CO 80309 (United States); Wagner, K.H. [University of Colorado, Boulder, CO 80309 (United States)

    2007-11-15

    This paper outlines the efforts to develop an ultra-wideband spectrum analyzer that takes advantage of the broad spectral response and fine spectral resolution ({approx}25 kHz) of spatial-spectral (S2) materials. The S2 material can process the full spectrum of broadband microwave transmissions, with adjustable time apertures (down to 100 {mu}s) and fast update rates (up to 1 kHz). A cryogenically cooled Tm:YAG crystal that operates on microwave signals modulated onto a stabilized optical carrier at 793 nm is used as the core for the spectrum analyzer. Efforts to develop novel component technologies that enhance the performance of the system and meet the application requirements are discussed, including an end-to-end device model for parameter optimization. We discuss the characterization of new ultra-wide bandwidth S2 materials. Detection and post-processing module development including the implementation of a novel spectral recovery algorithm using field programmable gate array technology (FPGA) is also discussed.

  3. [An improved low spectral distortion PCA fusion method].

    Science.gov (United States)

    Peng, Shi; Zhang, Ai-Wu; Li, Han-Lun; Hu, Shao-Xing; Meng, Xian-Gang; Sun, Wei-Dong

    2013-10-01

    Aiming at the spectral distortion produced in PCA fusion process, the present paper proposes an improved low spectral distortion PCA fusion method. This method uses NCUT (normalized cut) image segmentation algorithm to make a complex hyperspectral remote sensing image into multiple sub-images for increasing the separability of samples, which can weaken the spectral distortions of traditional PCA fusion; Pixels similarity weighting matrix and masks were produced by using graph theory and clustering theory. These masks are used to cut the hyperspectral image and high-resolution image into some sub-region objects. All corresponding sub-region objects between the hyperspectral image and high-resolution image are fused by using PCA method, and all sub-regional integration results are spliced together to produce a new image. In the experiment, Hyperion hyperspectral data and Rapid Eye data were used. And the experiment result shows that the proposed method has the same ability to enhance spatial resolution and greater ability to improve spectral fidelity performance.

  4. The spectral irradiance traceability chain at PTB

    International Nuclear Information System (INIS)

    Sperfeld, P.; Pape, S.; Nevas, S.

    2013-01-01

    Spectral irradiance is a fundamental radiometric unit. Its application to measurement results requires qualified traceability to basic units of the international system of units (Système international d’unités, SI). The Physikalisch-Technische Bundesanstalt (PTB) is amongst other national metrological institutes (NMIs) responsible for the realization, maintenance and dissemination of various radiometric and photometric units based on and traceable to national standards. The unit of spectral irradiance is realized and represented by a blackbody-radiator as the national primary standard of the PTB. Based on Planck’s radiation law, the irradiance is calculated and realized for any wavelength taking into account the exact knowledge of the radiation temperature and the geometrical parameters. Using a double-monochromator-based spectroradiometer system, secondary standard lamps can be calibrated by direct comparison to the blackbody-radiator (substitution method). These secondary standard lamps are then used at the PTB to calibrate standard lamps of customers. The customers themselves use these so-called transfer standards to calibrate their working standard lamps. These working standards are then used to calibrate own spectroradiometers or sources. This rather complex calibration chain is a common procedural method that for the customers generally leads to satisfying measurement results on site. Nevertheless, the standard lamps in use have to fulfill highest requirements concerning stability and reproducibility. Only this allows achieving comparably low transfer measurement uncertainties, which occur at each calibration step. Thus, the PTB is constantly investigating the improvement and further development of transfer standards and measurement methods for various spectral regions. The realization and dissemination of the spectral irradiance using the blackbody-radiator at the PTB is accomplished with worldwide approved minimized measurement uncertainties confirmed

  5. The spectral irradiance traceability chain at PTB

    Energy Technology Data Exchange (ETDEWEB)

    Sperfeld, P.; Pape, S.; Nevas, S. [Physikalisch-Technische Bundesanstalt, Bundesallee 10, 381160 Braunschweig (Germany)

    2013-05-10

    Spectral irradiance is a fundamental radiometric unit. Its application to measurement results requires qualified traceability to basic units of the international system of units (Systeme international d'unites, SI). The Physikalisch-Technische Bundesanstalt (PTB) is amongst other national metrological institutes (NMIs) responsible for the realization, maintenance and dissemination of various radiometric and photometric units based on and traceable to national standards. The unit of spectral irradiance is realized and represented by a blackbody-radiator as the national primary standard of the PTB. Based on Planck's radiation law, the irradiance is calculated and realized for any wavelength taking into account the exact knowledge of the radiation temperature and the geometrical parameters. Using a double-monochromator-based spectroradiometer system, secondary standard lamps can be calibrated by direct comparison to the blackbody-radiator (substitution method). These secondary standard lamps are then used at the PTB to calibrate standard lamps of customers. The customers themselves use these so-called transfer standards to calibrate their working standard lamps. These working standards are then used to calibrate own spectroradiometers or sources. This rather complex calibration chain is a common procedural method that for the customers generally leads to satisfying measurement results on site. Nevertheless, the standard lamps in use have to fulfill highest requirements concerning stability and reproducibility. Only this allows achieving comparably low transfer measurement uncertainties, which occur at each calibration step. Thus, the PTB is constantly investigating the improvement and further development of transfer standards and measurement methods for various spectral regions. The realization and dissemination of the spectral irradiance using the blackbody-radiator at the PTB is accomplished with worldwide approved minimized measurement uncertainties

  6. Dual-camera design for coded aperture snapshot spectral imaging.

    Science.gov (United States)

    Wang, Lizhi; Xiong, Zhiwei; Gao, Dahua; Shi, Guangming; Wu, Feng

    2015-02-01

    Coded aperture snapshot spectral imaging (CASSI) provides an efficient mechanism for recovering 3D spectral data from a single 2D measurement. However, since the reconstruction problem is severely underdetermined, the quality of recovered spectral data is usually limited. In this paper we propose a novel dual-camera design to improve the performance of CASSI while maintaining its snapshot advantage. Specifically, a beam splitter is placed in front of the objective lens of CASSI, which allows the same scene to be simultaneously captured by a grayscale camera. This uncoded grayscale measurement, in conjunction with the coded CASSI measurement, greatly eases the reconstruction problem and yields high-quality 3D spectral data. Both simulation and experimental results demonstrate the effectiveness of the proposed method.

  7. The even and the odd spectral flows on the N=2 superconformal algebras

    International Nuclear Information System (INIS)

    Gato-Rivera, B.

    1998-01-01

    There are two different spectral flows on the N=2 superconformal algebras (four in the case of the topological algebra). The usual spectral flow, first considered by Schwimmer and Seiberg, is an even transformation, whereas the spectral flow previously considered by the author and Rosado is an odd transformation. We show that the even spectral flow is generated by the odd spectral flow, and therefore only the latter is fundamental. We also analyze thoroughly the four ''topological'' spectral flows, writing two of them here for the first time. Whereas the even and the odd spectral flows have quasi-mirrored properties acting on the antiperiodic or the periodic algebras, the topological even and odd spectral flows have drastically different properties acting on the topological algebra. The other two topological spectral flows have mixed even and odd properties. We show that the even and the even-odd topological spectral flows are generated by the odd and the odd-even topological spectral flows, and therefore only the latter are fundamental. (orig.)

  8. Spectrally selective paint coatings. Preparation and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Crnjak Orel, Z.C.; Klanjsek Gunde, M. [National Institute of Chemistry, Hajdrihova 19, SI-1000 Ljubljana (Slovenia)

    2001-06-01

    Preparation and characterization of spectrally selective paint coating for photothermal solar energy conversion are discussed. The applied methods for preparation of paints with described measurements and calculations of black-pigmented coatings were reviewed. The article represents not only possible future applications but also past and current applications of spectrally selective paint coating which are used all over the world since the 1980s. Spectrally selective paint coatings based on combinations of two types of resins, various types of pigments and three types of silica, were prepared. The influence of pigment type and pigment volume concentration (PVC) was studied by applying the Kubelka-Munk (K-M) theory. The relation between the degrees of dispersion and distribution of pigment particles across the paint layer is discussed in terms of K-M coefficients.

  9. Characterization of the titanium Kβ spectral profile

    International Nuclear Information System (INIS)

    Chantler, C T; Smale, L F; Kinnane, M N; Illig, A J; Kimpton, J A; Crosby, D N

    2013-01-01

    Transition metals have Kα and Kβ characteristic radiation possessing complex asymmetric spectral profiles. Instrumental broadening normally encountered in x-ray experiments shifts features of profiles used for calibration, such as peak energy, by many times the quoted accuracies. We measure and characterize the titanium Kβ spectral profile. The peak energy of the titanium Kβ spectral profile is found to be 4931.966 ± 0.022 eV prior to instrumental broadening. This 4.5 ppm result decreases the uncertainty over the past literature by a factor of 2.6 and is 2.4 standard deviations from the previous standard. The spectrum is analysed and the resolution-free lineshape is extracted and listed for use in other experiments. We also incorporate improvement in analysis applied to earlier results for V Kβ. (paper)

  10. Relationship between behavioral and physiological spectral-ripple discrimination.

    Science.gov (United States)

    Won, Jong Ho; Clinard, Christopher G; Kwon, Seeyoun; Dasika, Vasant K; Nie, Kaibao; Drennan, Ward R; Tremblay, Kelly L; Rubinstein, Jay T

    2011-06-01

    Previous studies have found a significant correlation between spectral-ripple discrimination and speech and music perception in cochlear implant (CI) users. This relationship could be of use to clinicians and scientists who are interested in using spectral-ripple stimuli in the assessment and habilitation of CI users. However, previous psychoacoustic tasks used to assess spectral discrimination are not suitable for all populations, and it would be beneficial to develop methods that could be used to test all age ranges, including pediatric implant users. Additionally, it is important to understand how ripple stimuli are processed in the central auditory system and how their neural representation contributes to behavioral performance. For this reason, we developed a single-interval, yes/no paradigm that could potentially be used both behaviorally and electrophysiologically to estimate spectral-ripple threshold. In experiment 1, behavioral thresholds obtained using the single-interval method were compared to thresholds obtained using a previously established three-alternative forced-choice method. A significant correlation was found (r = 0.84, p = 0.0002) in 14 adult CI users. The spectral-ripple threshold obtained using the new method also correlated with speech perception in quiet and noise. In experiment 2, the effect of the number of vocoder-processing channels on the behavioral and physiological threshold in normal-hearing listeners was determined. Behavioral thresholds, using the new single-interval method, as well as cortical P1-N1-P2 responses changed as a function of the number of channels. Better behavioral and physiological performance (i.e., better discrimination ability at higher ripple densities) was observed as more channels added. In experiment 3, the relationship between behavioral and physiological data was examined. Amplitudes of the P1-N1-P2 "change" responses were significantly correlated with d' values from the single-interval behavioral

  11. Spectral Theory of Chemical Bonding

    National Research Council Canada - National Science Library

    Langhoff, P. W; Boatz, J. A; Hinde, R. J; Sheehy, J. A

    2004-01-01

    .... Wave function antisymmetry in the aggregate atomic spectral-product basis is enforced by unitary transformation performed subsequent to formation of the Hamiltonian matrix, greatly simplifying its construction...

  12. Fourier spectral simulations for wake fields in conducting cavities

    International Nuclear Information System (INIS)

    Min, M.; Chin, Y.-H.; Fischer, P.F.; Chae, Y.-Chul; Kim, K.-J.

    2007-01-01

    We investigate Fourier spectral time-domain simulations applied to wake field calculations in two-dimensional cylindrical structures. The scheme involves second-order explicit leap-frogging in time and Fourier spectral approximation in space, which is obtained from simply replacing the spatial differentiation operator of the YEE scheme by the Fourier differentiation operator on nonstaggered grids. This is a first step toward investigating high-order computational techniques with the Fourier spectral method, which is relatively simple to implement.

  13. A spectral/B-spline method for the Navier-Stokes equations in unbounded domains

    International Nuclear Information System (INIS)

    Dufresne, L.; Dumas, G.

    2003-01-01

    The numerical method presented in this paper aims at solving the incompressible Navier-Stokes equations in unbounded domains. The problem is formulated in cylindrical coordinates and the method is based on a Galerkin approximation scheme that makes use of vector expansions that exactly satisfy the continuity constraint. More specifically, the divergence-free basis vector functions are constructed with Fourier expansions in the θ and z directions while mapped B-splines are used in the semi-infinite radial direction. Special care has been taken to account for the particular analytical behaviors at both end points r=0 and r→∞. A modal reduction algorithm has also been implemented in the azimuthal direction, allowing for a relaxation of the CFL constraint on the timestep size and a possibly significant reduction of the number of DOF. The time marching is carried out using a mixed quasi-third order scheme. Besides the advantages of a divergence-free formulation and a quasi-spectral convergence, the local character of the B-splines allows for a great flexibility in node positioning while keeping narrow bandwidth matrices. Numerical tests show that the present method compares advantageously with other similar methodologies using purely global expansions

  14. Variational Multi-Scale method with spectral approximation of the sub-scales.

    KAUST Repository

    Dia, Ben Mansour

    2015-01-07

    A variational multi-scale method where the sub-grid scales are computed by spectral approximations is presented. It is based upon an extension of the spectral theorem to non necessarily self-adjoint elliptic operators that have an associated base of eigenfunctions which are orthonormal in weighted L2 spaces. We propose a feasible VMS-spectral method by truncation of this spectral expansion to a nite number of modes.

  15. Performance Evaluation of Spectral Clustering Algorithm using Various Clustering Validity Indices

    OpenAIRE

    M. T. Somashekara; D. Manjunatha

    2014-01-01

    In spite of the popularity of spectral clustering algorithm, the evaluation procedures are still in developmental stage. In this article, we have taken benchmarking IRIS dataset for performing comparative study of twelve indices for evaluating spectral clustering algorithm. The results of the spectral clustering technique were also compared with k-mean algorithm. The validity of the indices was also verified with accuracy and (Normalized Mutual Information) NMI score. Spectral clustering algo...

  16. Evidence of across-channel processing for spectral-ripple discrimination in cochlear implant listeners.

    Science.gov (United States)

    Won, Jong Ho; Jones, Gary L; Drennan, Ward R; Jameyson, Elyse M; Rubinstein, Jay T

    2011-10-01

    Spectral-ripple discrimination has been used widely for psychoacoustical studies in normal-hearing, hearing-impaired, and cochlear implant listeners. The present study investigated the perceptual mechanism for spectral-ripple discrimination in cochlear implant listeners. The main goal of this study was to determine whether cochlear implant listeners use a local intensity cue or global spectral shape for spectral-ripple discrimination. The effect of electrode separation on spectral-ripple discrimination was also evaluated. Results showed that it is highly unlikely that cochlear implant listeners depend on a local intensity cue for spectral-ripple discrimination. A phenomenological model of spectral-ripple discrimination, as an "ideal observer," showed that a perceptual mechanism based on discrimination of a single intensity difference cannot account for performance of cochlear implant listeners. Spectral modulation depth and electrode separation were found to significantly affect spectral-ripple discrimination. The evidence supports the hypothesis that spectral-ripple discrimination involves integrating information from multiple channels. © 2011 Acoustical Society of America

  17. USGS Spectral Library Version 7

    Science.gov (United States)

    Kokaly, Raymond F.; Clark, Roger N.; Swayze, Gregg A.; Livo, K. Eric; Hoefen, Todd M.; Pearson, Neil C.; Wise, Richard A.; Benzel, William M.; Lowers, Heather A.; Driscoll, Rhonda L.; Klein, Anna J.

    2017-04-10

    We have assembled a library of spectra measured with laboratory, field, and airborne spectrometers. The instruments used cover wavelengths from the ultraviolet to the far infrared (0.2 to 200 microns [μm]). Laboratory samples of specific minerals, plants, chemical compounds, and manmade materials were measured. In many cases, samples were purified, so that unique spectral features of a material can be related to its chemical structure. These spectro-chemical links are important for interpreting remotely sensed data collected in the field or from an aircraft or spacecraft. This library also contains physically constructed as well as mathematically computed mixtures. Four different spectrometer types were used to measure spectra in the library: (1) Beckman™ 5270 covering the spectral range 0.2 to 3 µm, (2) standard, high resolution (hi-res), and high-resolution Next Generation (hi-resNG) models of Analytical Spectral Devices (ASD) field portable spectrometers covering the range from 0.35 to 2.5 µm, (3) Nicolet™ Fourier Transform Infra-Red (FTIR) interferometer spectrometers covering the range from about 1.12 to 216 µm, and (4) the NASA Airborne Visible/Infra-Red Imaging Spectrometer AVIRIS, covering the range 0.37 to 2.5 µm. Measurements of rocks, soils, and natural mixtures of minerals were made in laboratory and field settings. Spectra of plant components and vegetation plots, comprising many plant types and species with varying backgrounds, are also in this library. Measurements by airborne spectrometers are included for forested vegetation plots, in which the trees are too tall for measurement by a field spectrometer. This report describes the instruments used, the organization of materials into chapters, metadata descriptions of spectra and samples, and possible artifacts in the spectral measurements. To facilitate greater application of the spectra, the library has also been convolved to selected spectrometer and imaging spectrometers sampling and

  18. High-performance Negative Database for Massive Data Management System of The Mingantu Spectral Radioheliograph

    Science.gov (United States)

    Shi, Congming; Wang, Feng; Deng, Hui; Liu, Yingbo; Liu, Cuiyin; Wei, Shoulin

    2017-08-01

    As a dedicated synthetic aperture radio interferometer in China, the MingantU SpEctral Radioheliograph (MUSER), initially known as the Chinese Spectral RadioHeliograph (CSRH), has entered the stage of routine observation. More than 23 million data records per day need to be effectively managed to provide high-performance data query and retrieval for scientific data reduction. In light of these massive amounts of data generated by the MUSER, in this paper, a novel data management technique called the negative database (ND) is proposed and used to implement a data management system for the MUSER. Based on the key-value database, the ND technique makes complete utilization of the complement set of observational data to derive the requisite information. Experimental results showed that the proposed ND can significantly reduce storage volume in comparison with a relational database management system (RDBMS). Even when considering the time needed to derive records that were absent, its overall performance, including querying and deriving the data of the ND, is comparable with that of a relational database management system (RDBMS). The ND technique effectively solves the problem of massive data storage for the MUSER and is a valuable reference for the massive data management required in next-generation telescopes.

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

    Science.gov (United States)

    Liu, Huanjun; Zhang, Xiaokang; Zhang, Xinle

    2016-04-01

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

  20. SPECTRAL RECONSTRUCTION BASED ON SVM FOR CROSS CALIBRATION

    Directory of Open Access Journals (Sweden)

    H. Gao

    2017-05-01

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

  1. 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.

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

    International Nuclear Information System (INIS)

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

    2008-01-01

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

  3. A system for time-resolved x-ray diffraction and its application to muscle contraction

    International Nuclear Information System (INIS)

    Amemiya, Yoshiyuki; Hashizume, Hiroo.

    1979-01-01

    A data-collection system has been built which permits time-resolved studies of X-ray diffraction diagrams obtained from contracting muscle on millisecond time scale. The system consists of a linear delay-line position sensitive proportional counter (PSPC), a special data transfer unit and an on-line computer. The PSPC used with a mirror-monochromator camera can detect equatorial reflections from stimulated muscle in a total exposure time of a few seconds. Time-resolved data-collection is achieved by stimulating muscle at a regular time interval, dividing a complete cycle of muscle contraction into many successive time slices and accumulating in computer memory X-ray data for each time slice from many repeated cycles of stimulation. The performances of the system have been demonstrated by recording equatorial reflections from frog skeletal muscle during isometric and isotonic twitch with a time resolution of 25 ms. (author)

  4. Hybrid Spectral Micro-CT: System Design, Implementation, and Preliminary Results

    CERN Document Server

    Bennett, James R; Xu, Qiong; Yu, Hengyong; Walsh, Michael; Butler, Anthony; Butler, Phillip; Cao, Guohua; Mohs, Aaron; Wang, Ge

    2014-01-01

    Spectral CT has proven an important development in biomedical imaging, and there have been several publications in the past years demonstrating its merits in pre-clinical and clinical applications. In 2012, Xu et al. reported that near-term implementation of spectral micro-CT could be enhanced by a hybrid architecture: a narrow-beam spectral "interior" imaging chain integrated with a traditional wide-beam "global" imaging chain. This hybrid integration coupled with compressive sensing (CS)-based interior tomography demonstrated promising results for improved contrast resolution, and decreased system cost and radiation dose. The motivation for the current study is implementation and evaluation of the hybrid architecture with a first-of-its-kind hybrid spectral micro-CT system. Preliminary results confirm improvements in both contrast and spatial resolution. This technology is shown to merit further investigation and potential application in future spectral CT scanner design.

  5. Development of spectral analysis math models and software program and spectral analyzer, digital converter interface equipment design

    Science.gov (United States)

    Hayden, W. L.; Robinson, L. H.

    1972-01-01

    Spectral analyses of angle-modulated communication systems is studied by: (1) performing a literature survey of candidate power spectrum computational techniques, determining the computational requirements, and formulating a mathematical model satisfying these requirements; (2) implementing the model on UNIVAC 1230 digital computer as the Spectral Analysis Program (SAP); and (3) developing the hardware specifications for a data acquisition system which will acquire an input modulating signal for SAP. The SAP computational technique uses extended fast Fourier transform and represents a generalized approach for simple and complex modulating signals.

  6. Hyper-Spectral Imager in visible and near-infrared band for lunar ...

    Indian Academy of Sciences (India)

    India's first lunar mission, Chandrayaan-1, will have a Hyper-Spectral Imager in the visible and near-infrared spectral ... mapping of the Moon's crust in a large number of spectral channels. The planned .... In-flight verification may be done.

  7. Characterization of spectral compression of OFDM symbols using optical time lenses

    DEFF Research Database (Denmark)

    Røge, Kasper Meldgaard; Guan, Pengyu; Kjøller, Niels-Kristian

    2015-01-01

    We present a detailed investigation of a double-time-lens subsystem for spectral compression of OFDM symbols. We derive optimized parameter settings by simulations and experimental characterization. The required chirp for OFDM spectral compression is very large.......We present a detailed investigation of a double-time-lens subsystem for spectral compression of OFDM symbols. We derive optimized parameter settings by simulations and experimental characterization. The required chirp for OFDM spectral compression is very large....

  8. All-optical OFDM demultiplexing by spectral magnification and band-pass filtering.

    Science.gov (United States)

    Palushani, E; Mulvad, H C Hansen; Kong, D; Guan, P; Galili, M; Oxenløwe, L K

    2014-01-13

    We propose a simple OFDM receiver allowing for the use of standard WDM receivers to receive spectrally advanced OFDM signals. We propose to spectrally magnify the optical-OFDM super-channels using a spectral telescope consisting of two time-lenses, which enables reduced inter-carrier-interference in subcarrier detection by simple band-pass filtering. A demonstration on an emulated 100 Gbit/s DPSK optical-OFDM channel shows improved sensitivities after 4-times spectral magnification.

  9. Thermal infrared spectral analysis of compacted fine-grained mineral mixtures: implications for spectral interpretation of lithified sedimentary materials on Mars

    Science.gov (United States)

    Pan, C.; Rogers, D.

    2012-12-01

    Characterizing the thermal infrared (TIR) spectral mixing behavior of compacted fine-grained mineral assemblages is necessary for facilitating quantitative mineralogy of sedimentary surfaces from spectral measurements. Previous researchers have demonstrated that TIR spectra from igneous and metamorphic rocks as well as coarse-grained (>63 micron) sand mixtures combine in proportion to their volume abundance. However, the spectral mixing behavior of compacted, fine-grained mineral mixtures that would be characteristic of sedimentary depositional environments has received little attention. Here we characterize the spectral properties of pressed pellet samples of pestle and centrifuged to obtain less than 10 micron size. Pure phases and mixtures of two, three and four components were made in varying proportions by volume. All of the samples were pressed into pellets at 15000PSI to minimize volume scattering. Thermal infrared spectra of pellets were measured in the Vibrational Spectroscopy Laboratory at Stony Brook University with a Thermo Fisher Nicolet 6700 Fourier transform infrared Michelson interferometer from ~225 to 2000 cm-1. Our preliminary results indicate that some pelletized samples have contributions from volume scattering, which leads to non-linear spectral combinations. It is not clear if the transparency features (which arise from multiple surface reflections of incident photons) are due to minor clinging fines on an otherwise specular pellet surface or to partially transmitted energy through optically thin grains in the compacted mixture. Inclusion of loose powder (analysis of TES and Mini-TES data of lithified sedimentary deposits.

  10. Regularized image denoising based on spectral gradient optimization

    International Nuclear Information System (INIS)

    Lukić, Tibor; Lindblad, Joakim; Sladoje, Nataša

    2011-01-01

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

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

    Science.gov (United States)

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

    2018-04-25

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

  12. BLAZAR SPECTRAL PROPERTIES AT 74 MHz

    Energy Technology Data Exchange (ETDEWEB)

    Massaro, F.; Funk, S. [SLAC National Laboratory and Kavli Institute for Particle Astrophysics and Cosmology, 2575 Sand Hill Road, Menlo Park, CA 94025 (United States); Giroletti, M. [INAF Istituto di Radioastronomia, via Gobetti 101, I-40129 Bologna (Italy); Paggi, A.; D' Abrusco, R. [Harvard-Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States); Tosti, G. [Dipartimento di Fisica, Università degli Studi di Perugia, I-06123 Perugia (Italy)

    2013-10-01

    Blazars are the most extreme class of active galactic nuclei. Despite a previous investigation at 102 MHz for a small sample of BL Lac objects and our recent analysis of blazars detected in the Westerbork Northern Sky Survey, a systematic study of the blazar spectral properties at frequencies below 100 MHz has been never carried out. In this paper, we present the first analysis of the radio spectral behavior of blazars based on the recent Very Large Array Low-frequency Sky Survey (VLSS) at 74 MHz. We search for blazar counterparts in the VLSS catalog, confirming that they are detected at 74 MHz. We then show that blazars present radio-flat spectra (i.e., radio spectral indices of ∼0.5) when evaluated, which also about an order of magnitude in frequency lower than previous analyses. Finally, we discuss the implications of our findings in the context of the blazars-radio galaxies connection since the low-frequency radio data provide a new diagnostic tool to verify the expectations of the unification scenario for radio-loud active galaxies.

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

    DEFF Research Database (Denmark)

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

    2017-01-01

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

  14. Terahertz Josephson spectral analysis and its applications

    Science.gov (United States)

    Snezhko, A. V.; Gundareva, I. I.; Lyatti, M. V.; Volkov, O. Y.; Pavlovskiy, V. V.; Poppe, U.; Divin, Y. Y.

    2017-04-01

    Principles of Hilbert-transform spectral analysis (HTSA) are presented and advantages of the technique in the terahertz (THz) frequency range are discussed. THz HTSA requires Josephson junctions with high values of characteristic voltages I c R n and dynamics described by a simple resistively shunted junction (RSJ) model. To meet these requirements, [001]- and [100]-tilt YBa2Cu3O7-x bicrystal junctions with deviations from the RSJ model less than 1% have been developed. Demonstrators of Hilbert-transform spectrum analyzers with various cryogenic environments, including integration into Stirling coolers, are described. Spectrum analyzers have been characterized in the spectral range from 50 GHz to 3 THz. Inside a power dynamic range of five orders, an instrumental function of the analyzers has been found to have a Lorentz form around a single frequency of 1.48 THz with a spectral resolution as low as 0.9 GHz. Spectra of THz radiation from optically pumped gas lasers and semiconductor frequency multipliers have been studied with these spectrum analyzers and the regimes of these radiation sources were optimized for a single-frequency operation. Future applications of HTSA will be related with quick and precise spectral characterization of new radiation sources and identification of substances in the THz frequency range.

  15. Validation of spectral gas radiation models under oxyfuel conditions

    Energy Technology Data Exchange (ETDEWEB)

    Becher, Johann Valentin

    2013-05-15

    Combustion of hydrocarbon fuels with pure oxygen results in a different flue gas composition than combustion with air. Standard computational-fluid-dynamics (CFD) spectral gas radiation models for air combustion are therefore out of their validity range in oxyfuel combustion. This thesis provides a common spectral basis for the validation of new spectral models. A literature review about fundamental gas radiation theory, spectral modeling and experimental methods provides the reader with a basic understanding of the topic. In the first results section, this thesis validates detailed spectral models with high resolution spectral measurements in a gas cell with the aim of recommending one model as the best benchmark model. In the second results section, spectral measurements from a turbulent natural gas flame - as an example for a technical combustion process - are compared to simulated spectra based on measured gas atmospheres. The third results section compares simplified spectral models to the benchmark model recommended in the first results section and gives a ranking of the proposed models based on their accuracy. A concluding section gives recommendations for the selection and further development of simplified spectral radiation models. Gas cell transmissivity spectra in the spectral range of 2.4 - 5.4 {mu}m of water vapor and carbon dioxide in the temperature range from 727 C to 1500 C and at different concentrations were compared in the first results section at a nominal resolution of 32 cm{sup -1} to line-by-line models from different databases, two statistical-narrow-band models and the exponential-wide-band model. The two statistical-narrow-band models EM2C and RADCAL showed good agreement with a maximal band transmissivity deviation of 3 %. The exponential-wide-band model showed a deviation of 6 %. The new line-by-line database HITEMP2010 had the lowest band transmissivity deviation of 2.2% and was therefore recommended as a reference model for the

  16. Spectral unmixing using the concept of pure variables

    DEFF Research Database (Denmark)

    Kucheryavskiy, Sergey V.

    2016-01-01

    This comprehensive book presents an interdisciplinary approach to demonstrate how and why data analysis, signal processing, and chemometrics are essential to resolving the spectral unmixing problem.......This comprehensive book presents an interdisciplinary approach to demonstrate how and why data analysis, signal processing, and chemometrics are essential to resolving the spectral unmixing problem....

  17. Using Image Texture and Spectral Reflectance Analysis to Detect Yellowness and Esca in Grapevines at Leaf-Level

    Directory of Open Access Journals (Sweden)

    Hania Al-Saddik

    2018-04-01

    Full Text Available Plant diseases are one of the main reasons behind major economic and production losses in the agricultural field. Current research activities enable large fields monitoring and plant disease detection using innovative and robust technologies. French grapevines have a reputation for producing premium quality wines, however, these major fruit crops are susceptible to many diseases, including Esca, Downy mildew, Powdery mildew, Yellowing, and many others. In this study, we focused on two main infections (Esca and Yellowing, and data were gathered from fields that were located in Aquitaine and Burgundy regions, France. Since plant diseases can be diagnosed from the properties of the leaf, we acquired both Red-Green-Blue (RGB digital image and hyperspectral reflectance data from infected and healthy leaves. Biophysical parameters that were produced by the PROSPECT model inversion together with texture parameters compiled from the literature were deduced. Then we investigated their relationship to damage caused by Yellowing and Esca. This study examined whether spectral and textural data can identify the two diseases through the use of Neural Networks. We obtained an overall accuracy of 99% for both of the diseases when textural and spectral data are combined. These results suggest that, first, biophysical parameters present a valid dimension reduction tool that could replace the use of complete hyperspectral data. Second, remote sensing using spectral reflectance and digital images can make an overall nondestructive, rapid, cost-effective, and reproducible technique to determine diseases in grapevines with a good level of accuracy.

  18. Spectral synchronicity in brain signals

    KAUST Repository

    de Jesus Euan Campos, Carolina; Ombao, Hernando; Ortega, Joaquí n

    2018-01-01

    This paper addresses the problem of identifying brain regions with similar oscillatory patterns detected from electroencephalograms. We introduce the hierarchical spectral merger (HSM) clustering method where the feature of interest is the spectral curve and the similarity metric used is the total variance distance. The HSM method is compared with clustering using features derived from independent-component analysis. Moreover, the HSM method is applied to 2 different electroencephalogram datasets. The first was recorded at resting state where the participant was not engaged in any cognitive task; the second was recorded during a spontaneous epileptic seizure. The results of the analyses using the HSM method demonstrate that clustering could evolve over the duration of the resting state and during epileptic seizure.

  19. Spectral synchronicity in brain signals

    KAUST Repository

    de Jesus Euan Campos, Carolina

    2018-05-04

    This paper addresses the problem of identifying brain regions with similar oscillatory patterns detected from electroencephalograms. We introduce the hierarchical spectral merger (HSM) clustering method where the feature of interest is the spectral curve and the similarity metric used is the total variance distance. The HSM method is compared with clustering using features derived from independent-component analysis. Moreover, the HSM method is applied to 2 different electroencephalogram datasets. The first was recorded at resting state where the participant was not engaged in any cognitive task; the second was recorded during a spontaneous epileptic seizure. The results of the analyses using the HSM method demonstrate that clustering could evolve over the duration of the resting state and during epileptic seizure.

  20. The potential of Sentinel-2 spectral configuration to assess rangeland quality

    CSIR Research Space (South Africa)

    Ramoelo, Abel

    2015-08-01

    Full Text Available was measured using the analytical spectral device (ASD) in concert with leaf sample collections for leaf N chemical analysis. ASD reflectance data were resampled to the spectral bands of Sentinel-2 using published spectral response functions. Random forest (RF...

  1. Technology for detecting spectral radiance by a snapshot multi-imaging spectroradiometer

    Science.gov (United States)

    Zuber, Ralf; Stührmann, Ansgar; Gugg-Helminger, Anton; Seckmeyer, Gunther

    2017-12-01

    Technologies to determine spectral sky radiance distributions have evolved in recent years and have enabled new applications in remote sensing, for sky radiance measurements, in biological/diagnostic applications and luminance measurements. Most classical spectral imaging radiance technologies are based on mechanical and/or spectral scans. However, these methods require scanning time in which the spectral radiance distribution might change. To overcome this limitation, different so-called snapshot spectral imaging technologies have been developed that enable spectral and spatial non-scanning measurements. We present a new setup based on a facet mirror that is already used in imaging slicing spectrometers. By duplicating the input image instead of slicing it and using a specially designed entrance slit, we are able to select nearly 200 (14 × 14) channels within the field of view (FOV) for detecting spectral radiance in different directions. In addition, a megapixel image of the FOV is captured by an additional RGB camera. This image can be mapped onto the snapshot spectral image. In this paper, the mechanical setup, technical design considerations and first measurement results of a prototype are presented. For a proof of concept, the device is radiometrically calibrated and a 10 mm × 10 mm test pattern measured within a spectral range of 380 nm-800 nm with an optical bandwidth of 10 nm (full width at half maximum or FWHM). To show its potential in the UV spectral region, zenith sky radiance measurements in the UV of a clear sky were performed. Hence, the prototype was equipped with an entrance optic with a FOV of 0.5° and modified to obtain a radiometrically calibrated spectral range of 280 nm-470 nm with a FWHM of 3 nm. The measurement results have been compared to modeled data processed by UVSPEC, which showed deviations of less than 30%. This is far from being ideal, but an acceptable result with respect to available state

  2. Quantum gravity boundary terms from the spectral action of noncommutative space.

    Science.gov (United States)

    Chamseddine, Ali H; Connes, Alain

    2007-08-17

    We study the boundary terms of the spectral action of the noncommutative space, defined by the spectral triple dictated by the physical spectrum of the standard model, unifying gravity with all other fundamental interactions. We prove that the spectral action predicts uniquely the gravitational boundary term required for consistency of quantum gravity with the correct sign and coefficient. This is a remarkable result given the lack of freedom in the spectral action to tune this term.

  3. Deconvolution of spectral line profile by FTS

    International Nuclear Information System (INIS)

    Lego, J.

    1977-01-01

    The possibility is studied of determining the components of the spectral line profile using Fourier transformation. The different types of the spectral line profiles are described and the conditions for their generation discussed. The main result is the discovery of the possibility to obtain the parameters of the different components directly from the interferogram without using the Fourier transformation. The method under discussion strongly simplifies evaluation while preserving or increasing accuracy. (author)

  4. Chemical exchange effects in spectral line shapes

    International Nuclear Information System (INIS)

    Diaz, M.A.; Veguillas, J.

    1990-01-01

    A theory of spectral-line shapes has been extended to the case in which relaxation broadening may be influenced by reactive interactions. This extension is valid for gaseous systems in the same way it is valid for condensed media, and particularly, for such chemical mechanisms as isomerizations. The dependence of the spectral rate on the chemical exchange rate is clarified. Finally, a discussion concerning the above aspects and their applications has been included. (author)

  5. Statistical Analysis of Spectral Properties and Prosodic Parameters of Emotional Speech

    Science.gov (United States)

    Přibil, J.; Přibilová, A.

    2009-01-01

    The paper addresses reflection of microintonation and spectral properties in male and female acted emotional speech. Microintonation component of speech melody is analyzed regarding its spectral and statistical parameters. According to psychological research of emotional speech, different emotions are accompanied by different spectral noise. We control its amount by spectral flatness according to which the high frequency noise is mixed in voiced frames during cepstral speech synthesis. Our experiments are aimed at statistical analysis of cepstral coefficient values and ranges of spectral flatness in three emotions (joy, sadness, anger), and a neutral state for comparison. Calculated histograms of spectral flatness distribution are visually compared and modelled by Gamma probability distribution. Histograms of cepstral coefficient distribution are evaluated and compared using skewness and kurtosis. Achieved statistical results show good correlation comparing male and female voices for all emotional states portrayed by several Czech and Slovak professional actors.

  6. Evolutionary Computing Methods for Spectral Retrieval

    Science.gov (United States)

    Terrile, Richard; Fink, Wolfgang; Huntsberger, Terrance; Lee, Seugwon; Tisdale, Edwin; VonAllmen, Paul; Tinetti, Geivanna

    2009-01-01

    A methodology for processing spectral images to retrieve information on underlying physical, chemical, and/or biological phenomena is based on evolutionary and related computational methods implemented in software. In a typical case, the solution (the information that one seeks to retrieve) consists of parameters of a mathematical model that represents one or more of the phenomena of interest. The methodology was developed for the initial purpose of retrieving the desired information from spectral image data acquired by remote-sensing instruments aimed at planets (including the Earth). Examples of information desired in such applications include trace gas concentrations, temperature profiles, surface types, day/night fractions, cloud/aerosol fractions, seasons, and viewing angles. The methodology is also potentially useful for retrieving information on chemical and/or biological hazards in terrestrial settings. In this methodology, one utilizes an iterative process that minimizes a fitness function indicative of the degree of dissimilarity between observed and synthetic spectral and angular data. The evolutionary computing methods that lie at the heart of this process yield a population of solutions (sets of the desired parameters) within an accuracy represented by a fitness-function value specified by the user. The evolutionary computing methods (ECM) used in this methodology are Genetic Algorithms and Simulated Annealing, both of which are well-established optimization techniques and have also been described in previous NASA Tech Briefs articles. These are embedded in a conceptual framework, represented in the architecture of the implementing software, that enables automatic retrieval of spectral and angular data and analysis of the retrieved solutions for uniqueness.

  7. Tomographic spectral imaging: microanalysis in 3D

    International Nuclear Information System (INIS)

    Kotula, P.G.; Keenan, M.R.; Michael, J.R.

    2003-01-01

    Full text: Spectral imaging, where a series of complete x-ray spectra are typically collected from a 2D area, holds great promise for comprehensive near-surface microanalysis. There are however numerous microanalysis problems where 3D chemical information is needed as well. In the SEM, some sort of sectioning (either mechanical or with a focused ion beam (FIB) tool) followed by x-ray mapping has, in the past, been utilized in an attempt to perform 3D microanalysis. Reliance on simple mapping has the potential to miss important chemical features as well as misidentify others. In this paper we will describe the acquisition of serial-section tomographic spectral images (TSI) with a dual-beam FIB/SEM equipped with an EDS system. We will also describe the application of a modified version of our multivariate statistical analysis algorithms to TSIs. Serial sectioning was performed with a FEI DB-235 FIB/SEM. Firstly, the specimen normal was tilted to the optic axis of the FIB column and a trench was milled into the surface of the specimen. A second trench was then milled perpendicular to the first to provide visibility of the entire analysis surface to the x-ray detector. In addition, several fiducial markers were milled into the surface to allow for alignment from slice to slice. The electron column is at an angle of 52 deg to the ion column so the electron beam can 'see' the analysis surface milled by the FIB with no additional specimen tilting or rotation. Likewise the x-ray detector is at a radial angle of 45 deg to the plane of the electron and ion columns (about the electron column) and a take-off-angle of 35 deg with respect to an untilted specimen so it can 'see' the analysis surface as well with no additional sample tilting or rotation. Spectral images were acquired from regions 40 μm wide and 20μm deep for each slice. Approximately 1μm/slice was milled and 10-12 total slices were cut. Spectral images were acquired with a Thermo NORAN Vantage (Digital imaging

  8. Opto-mechanical design of the MTG FCI spectral separation assembly

    Science.gov (United States)

    Riguet, François; Brousse, Emmanuel; Carel, Jean-Louis; Cottenye, Justine; Harmann, David; Joncour, Marc; Makhlouf, Houssine; Mouricaud, Daniel; Oussalah, Meihdi; Rodolfo, Jacques

    2015-09-01

    The Spectral Separation Assembly is a key component of the Flexible Combined Imager, an instrument that will be on-board Meteosat Third Generation. It splits the input beam coming from the telescope into five spectral groups, for a total of 16 channels, from 0.4 to 13.3 μm. It comprises a set of four dichroics separators followed by four collimating optics for the infrared spectral groups, which feed the cold imaging optics. The visible spectral group is directly imaged on a detector. This paper presents the optical design of the assembly, the mechanical mounting of the optical components, and the coatings developed for the dichroics, mirrors and lenses.

  9. Spectral and dual-energy X-ray imaging for medical applications

    Science.gov (United States)

    Fredenberg, Erik

    2018-01-01

    Spectral imaging is an umbrella term for energy-resolved X-ray imaging in medicine. The technique makes use of the energy dependence of X-ray attenuation to either increase the contrast-to-noise ratio, or to provide quantitative image data and reduce image artefacts by so-called material decomposition. Spectral imaging is not new, but has gained interest in recent years because of rapidly increasing availability of spectral and dual-energy CT and the dawn of energy-resolved photon-counting detectors. This review examines the current technological status of spectral and dual-energy imaging and a number of practical applications of the technology in medicine.

  10. All-optical OFDM demultiplexing by spectral magnification and band-pass filtering

    DEFF Research Database (Denmark)

    Palushani, Evarist; Mulvad, Hans Christian Hansen; Kong, Deming

    2014-01-01

    We propose a simple OFDM receiver allowing for the use of standard WDM receivers to receive spectrally advanced OFDM signals. We propose to spectrally magnify the optical-OFDM super-channels using a spectral telescope consisting of two time-lenses, which enables reduced inter-carrier-interference...

  11. Spectral methods in numerical plasma simulation

    International Nuclear Information System (INIS)

    Coutsias, E.A.; Hansen, F.R.; Huld, T.; Knorr, G.; Lynov, J.P.

    1989-01-01

    An introduction is given to the use of spectral methods in numerical plasma simulation. As examples of the use of spectral methods, solutions to the two-dimensional Euler equations in both a simple, doubly periodic region, and on an annulus will be shown. In the first case, the solution is expanded in a two-dimensional Fourier series, while a Chebyshev-Fourier expansion is employed in the second case. A new, efficient algorithm for the solution of Poisson's equation on an annulus is introduced. Problems connected to aliasing and to short wavelength noise generated by gradient steepening are discussed. (orig.)

  12. Spectral functions from Quantum Monte Carlo

    International Nuclear Information System (INIS)

    Silver, R.N.

    1989-01-01

    In his review, D. Scalapino identified two serious limitations on the application of Quantum Monte Carlo (QMC) methods to the models of interest in High T c Superconductivity (HTS). One is the ''sign problem''. The other is the ''analytic continuation problem'', which is how to extract electron spectral functions from QMC calculations of the imaginary time Green's functions. Through-out this Symposium on HTS, the spectral functions have been the focus for the discussion of normal state properties including the applicability of band theory, Fermi liquid theory, marginal Fermi liquids, and novel non-perturbative states. 5 refs., 1 fig

  13. Tensor-based Dictionary Learning for Spectral CT Reconstruction

    Science.gov (United States)

    Zhang, Yanbo; Wang, Ge

    2016-01-01

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

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

    Science.gov (United States)

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

    2017-01-01

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

  15. The MARS Photon Processing Cameras for Spectral CT

    CERN Document Server

    Doesburg, Robert Michael Nicholas; Butler, APH; Renaud, PF

    This thesis is about the development of the MARS camera: a stan- dalone portable digital x-ray camera with spectral sensitivity. It is built for use in the MARS Spectral system from the Medipix2 and Medipix3 imaging chips. Photon counting detectors and Spectral CT are introduced, and Medipix is identified as a powerful new imaging device. The goals and strategy for the MARS camera are discussed. The Medipix chip physical, electronic and functional aspects, and ex- perience gained, are described. The camera hardware, firmware and supporting PC software are presented. Reports of experimental work on the process of equalisation from noise, and of tests of charge sum- ming mode, conclude the main body of the thesis. The camera has been actively used since late 2009 in pre-clinical re- search. A list of publications that derive from the use of the camera and the MARS Spectral scanner demonstrates the practical benefits already obtained from this work. Two of the publications are first- author, eight are co-authore...

  16. Spectral Distortion in Lossy Compression of Hyperspectral Data

    Directory of Open Access Journals (Sweden)

    Bruno Aiazzi

    2012-01-01

    Full Text Available Distortion allocation varying with wavelength in lossy compression of hyperspectral imagery is investigated, with the aim of minimizing the spectral distortion between original and decompressed data. The absolute angular error, or spectral angle mapper (SAM, is used to quantify spectral distortion, while radiometric distortions are measured by maximum absolute deviation (MAD for near-lossless methods, for example, differential pulse code modulation (DPCM, or mean-squared error (MSE for lossy methods, for example, spectral decorrelation followed by JPEG 2000. Two strategies of interband distortion allocation are compared: given a target average bit rate, distortion may be set to be constant with wavelength. Otherwise, it may be allocated proportionally to the noise level of each band, according to the virtually lossless protocol. Comparisons with the uncompressed originals show that the average SAM of radiance spectra is minimized by constant distortion allocation to radiance data. However, variable distortion allocation according to the virtually lossless protocol yields significantly lower SAM in case of reflectance spectra obtained from compressed radiance data, if compared with the constant distortion allocation at the same compression ratio.

  17. Irregular conformal block, spectral curve and flow equations

    International Nuclear Information System (INIS)

    Choi, Sang Kwan; Rim, Chaiho; Zhang, Hong

    2016-01-01

    Irregular conformal block is motivated by the Argyres-Douglas type of N=2 super conformal gauge theory. We investigate the classical/NS limit of irregular conformal block using the spectral curve on a Riemann surface with irregular punctures, which is equivalent to the loop equation of irregular matrix model. The spectral curve is reduced to the second order (Virasoro symmetry, SU(2) for the gauge theory) and third order (W_3 symmetry, SU(3)) differential equations of a polynomial with finite degree. The conformal and W symmetry generate the flow equations in the spectral curve and determine the irregular conformal block, hence the partition function of the Argyres-Douglas theory ala AGT conjecture.

  18. Systematic Evaluation of Protein Reduction and Alkylation Reveals Massive Unspecific Side Effects by Iodine-containing Reagents.

    Science.gov (United States)

    Müller, Torsten; Winter, Dominic

    2017-07-01

    Reduction and alkylation of cysteine residues is part of virtually any proteomics workflow. Despite its frequent use, up to date no systematic investigation of the impact of different conditions on the outcome of proteomics studies has been performed. In this study, we compared common reduction reagents (dithiothreitol, tris-(2-carboxyethyl)-phosphine, and β-mercaptoethanol) and alkylation reagents (iodoacetamide, iodoacetic acid, acrylamide, and chloroacetamide). Using in-gel digests as well as SAX fractionated in-solution digests of cytosolic fractions of HeLa cells, we evaluated 13 different reduction and alkylation conditions resulting in considerably varying identification rates. We observed strong differences in offsite alkylation reactions at 7 amino acids as well as at the peptide N terminus, identifying single and double adducts of all reagents. Using dimethyl labeling, mass tolerant searches, and synthetic peptide experiments, we identified alkylation of methionine residues by iodine-containing alkylation reagents as one of the major factors for the differences. We observed differences of more than 9-fold in numbers of identified methionine-containing peptide spectral matches for in-gel digested samples between iodine- and noniodine-containing alkylation reagents. This was because of formation of carbamidomethylated and carboxymethylated methionine side chains and a resulting prominent neutral loss during ESI ionization or in MS/MS fragmentation, strongly decreasing identification rates of methionine-containing peptides. We achieved best results with acrylamide as alkylation reagent, whereas the highest numbers of peptide spectral matches were obtained when reducing with dithiothreitol and β-mercaptoethanol for the in-solution and the in-gel digested samples, respectively. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

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

    International Nuclear Information System (INIS)

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

    2014-01-01

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

  20. Multichannel spectral mode of the ALOHA up-conversion interferometer

    Science.gov (United States)

    Lehmann, L.; Darré, P.; Boulogne, H.; Delage, L.; Grossard, L.; Reynaud, F.

    2018-06-01

    In this paper, we propose a multichannel spectral configuration of the Astronomical Light Optical Hybrid Analysis (ALOHA) instrument dedicated to high-resolution imaging. A frequency conversion process is implemented in each arm of an interferometer to transfer the astronomical light to a shorter wavelength domain. Exploiting the spectral selectivity of this non-linear optical process, we propose to use a set of independent pump lasers in order to simultaneously study multiple spectral channels. This principle is experimentally demonstrated with a dual-channel configuration as a proof-of-principle.

  1. Spectral model for clear sky atmospheric longwave radiation

    Science.gov (United States)

    Li, Mengying; Liao, Zhouyi; Coimbra, Carlos F. M.

    2018-04-01

    An efficient spectrally resolved radiative model is used to calculate surface downwelling longwave (DLW) radiation (0 ∼ 2500 cm-1) under clear sky (cloud free) conditions at the ground level. The wavenumber spectral resolution of the model is 0.01 cm-1 and the atmosphere is represented by 18 non-uniform plane-parallel layers with pressure in each layer determined on a pressure-based coordinate system. The model utilizes the most up-to-date (2016) HITRAN molecular spectral data for 7 atmospheric gases: H2O, CO2, O3, CH4, N2O, O2 and N2. The MT_CKD model is used to calculate water vapor and CO2 continuum absorption coefficients. Longwave absorption and scattering coefficients for aerosols are modeled using Mie theory. For the non-scattering atmosphere (aerosol free), the surface DLW agrees within 2.91% with mean values from the InterComparison of Radiation Codes in Climate Models (ICRCCM) program, with spectral deviations below 0.035 W cm m-2. For a scattering atmosphere with typical aerosol loading, the DLW calculated by the proposed model agrees within 3.08% relative error when compared to measured values at 7 climatologically diverse SURFRAD stations. This relative error is smaller than a calibrated parametric model regressed from data for those same 7 stations, and within the uncertainty (+/- 5 W m-2) of pyrgeometers commonly used for meteorological and climatological applications. The DLW increases by 1.86 ∼ 6.57 W m-2 when compared with aerosol-free conditions, and this increment decreases with increased water vapor content due to overlap with water vapor bands. As expected, the water vapor content at the layers closest to the surface contributes the most to the surface DLW, especially in the spectral region 0 ∼ 700 cm-1. Additional water vapor content (mostly from the lowest 1 km of the atmosphere) contributes to the spectral range of 400 ∼ 650 cm-1. Low altitude aerosols ( ∼ 3.46 km or less) contribute to the surface value of DLW mostly in the

  2. Trojan Asteroids: Spectral Groups, Volatiles, and Rotational Variation

    Science.gov (United States)

    Emery, J. P.; Takir, D.; Stamper, N. G.; Lucas, M. P.

    2017-12-01

    Trojan asteroids comprise a substantial population of primitive bodies confined to Jupiter's stable Lagrange regions. ecause they likely became trapped in these orbits at the end of the initial phase of planetary formation and subsequent migration, the compositions of Trojans provide unique perspectives on chemical and dynamical processes that shaped the Solar System. Ices and organics are of particular interest for understanding Trojan histories. Published near-infrared (0.7 to 4.0 mm) spectra of Trojans show no absorption bands due to H2O or organics. However, if the Trojan asteroids formed at or beyond their present heliocentric distance of 5.2 AU and never spent significant amounts of time closer to the Sun, they should contain H2O ice. Two VNIR spectral groups exist within the Trojans: 2/3 of large Trojans form a cluster with very red (D-type-like) spectral slopes, while the other 1/3 cluster around less-red (P-type-like) slopes. Visible colors of smaller Trojans suggest that the ratio of red to less-red Trojans decreases with decreasing size, from which Wong and Brown (2015; AJ 150:174) suggest that the interiors of all Trojans are represented by the less-red spectral group. In order to further test the hypothesis that Trojans contain H­2O ice and complex organics and to test the result from visible colors that the spectral group ratio changes with size, we have measured near-infrared (0.8 - 2.5 μm) spectra of small ( 35 to 75 km) Trojans from both swarms using the SpeX spectrograph at the NASA Infrared Telescope Facility (IRTF). We have also measured 2 - 4 μm spectra of several Trojans to search for spectral signatures of H2O and organics. We confirm that the two spectral groups persist to smaller sizes, and we still detect no absorption features that would be diagnostic of composition. The spectrum of two large Trojans show evidence of spectral slope variations with rotation, but spectra of several others do not. We will present the new spectra and

  3. Spectral reflectance relationships to leaf water stress

    Science.gov (United States)

    Ripple, William J.

    1986-01-01

    Spectral reflectance data were collected from detached snapbean leaves in the laboratory with a multiband radiometer. Four experiments were designed to study the spectral response resulting from changes in leaf cover, relative water content of leaves, and leaf water potential. Spectral regions included in the analysis were red (630-690 nm), NIR (760-900 nm), and mid-IR (2.08-2.35 microns). The red and mid-IR bands showed sensitivity to changes in both leaf cover and relative water content of leaves. The NIR was only highly sensitive to changes in leaf cover. Results provided evidence that mid-IR reflectance was governed primarily by leaf moisture content, although soil reflectance was an important factor when leaf cover was less than 100 percent. High correlations between leaf water potentials and reflectance were attributed to covariances with relative water content of leaves and leaf cover.

  4. 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...

  5. Spectral identification of plant communities for mapping of semi-natural grasslands

    DEFF Research Database (Denmark)

    Jacobsen, Anne; Nielsen, Allan Aasbjerg; Ejrnæs, Rasmus

    2000-01-01

    identification of plant communities was based on a hierarchical approach relating the test sites to i) management (Ma) and ii) flora (Fl) using spectral consistency and separability as the main criteria. Evaluation of spectral consistency was based on unsupervised clustering of test sites of Ma classes 1 to 7...... as a measure of plant community heterogeneity within management classes. The spectral analysis as well as the maximum likelihood classification indicated that the source of spectral variation within management classes might be related to vegetation composition....

  6. Review of spectral imaging technology in biomedical engineering: achievements and challenges.

    Science.gov (United States)

    Li, Qingli; He, Xiaofu; Wang, Yiting; Liu, Hongying; Xu, Dongrong; Guo, Fangmin

    2013-10-01

    Spectral imaging is a technology that integrates conventional imaging and spectroscopy to get both spatial and spectral information from an object. Although this technology was originally developed for remote sensing, it has been extended to the biomedical engineering field as a powerful analytical tool for biological and biomedical research. This review introduces the basics of spectral imaging, imaging methods, current equipment, and recent advances in biomedical applications. The performance and analytical capabilities of spectral imaging systems for biological and biomedical imaging are discussed. In particular, the current achievements and limitations of this technology in biomedical engineering are presented. The benefits and development trends of biomedical spectral imaging are highlighted to provide the reader with an insight into the current technological advances and its potential for biomedical research.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-09-28

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

  8. Optical decoherence times and spectral diffusion in an Er-doped optical fiber measured by two-pulse echoes, stimulated photon echoes, and spectral hole burning

    International Nuclear Information System (INIS)

    Macfarlane, R.M.; Sun, Y.; Sellin, P.B.; Cone, R.L.

    2007-01-01

    Two-pulse and stimulated photon echoes and spectral hole burning were measured on the transition from the lowest component of the 4 I 15/2 manifold to the lowest component of 4 I 13/2 of Er 3+ in a silicate optical fiber at 1.6 K. The two-pulse echo decays gave decoherence times as long as 230 ns for magnetic fields above 2 T. A large field dependent contribution to the homogeneous line width of >2 MHz was found and interpreted in terms of coupling to magnetic tunneling modes (TLS) in the glass. The stimulated echoes measured at 2 T showed spectral diffusion of 0.8 MHz/decade of time between 0.4 and 500 μs. Spectral diffusion in this high field region is attributed to coupling to elastic TLS modes which have a distribution of flip rates in glasses. Time-resolved spectral hole burning at very low field showed stronger spectral diffusion of 5.7 MHz/decade of time, attributed to coupling to magnetic spin-elastic TLS modes

  9. A Fiber-Optic System Generating Pulses of High Spectral Density

    Science.gov (United States)

    Abramov, A. S.; Zolotovskii, I. O.; Korobko, D. A.; Fotiadi, A. A.

    2018-03-01

    A cascade fiber-optic system that generates pulses of high spectral density by using the effect of nonlinear spectral compression is proposed. It is demonstrated that the shape of the pulse envelope substantially influences the degree of compression of its spectrum. In so doing, maximum compression is achieved for parabolic pulses. The cascade system includes an optical fiber exhibiting normal dispersion that decreases along the fiber length, thereby ensuring that the pulse envelope evolves toward a parabolic shape, along with diffraction gratings and a fiber spectral compressor. Based on computer simulation, we determined parameters of cascade elements leading to maximum spectral density of radiation originating from a subpicosecond laser pulse of medium energy.

  10. A software sampling frequency adaptive algorithm for reducing spectral leakage

    Institute of Scientific and Technical Information of China (English)

    PAN Li-dong; WANG Fei

    2006-01-01

    Spectral leakage caused by synchronous error in a nonsynchronous sampling system is an important cause that reduces the accuracy of spectral analysis and harmonic measurement.This paper presents a software sampling frequency adaptive algorithm that can obtain the actual signal frequency more accurately,and then adjusts sampling interval base on the frequency calculated by software algorithm and modifies sampling frequency adaptively.It can reduce synchronous error and impact of spectral leakage;thereby improving the accuracy of spectral analysis and harmonic measurement for power system signal where frequency changes slowly.This algorithm has high precision just like the simulations show,and it can be a practical method in power system harmonic analysis since it can be implemented easily.

  11. Affinement spectral dans les lasers à colorants pulsés.

    Science.gov (United States)

    Flamant, P

    1978-03-15

    Spectral narrowing in pulsed dye lasers is studied theoretically. Fabry-Perot etalons, gratings, and prisms are considered as tuning elements. Each one is characterized by a new parameter: the spectral width associated with a round trip in the laser cavity. Numerical examples show that depending on cavity parameters it is either the round-trip spectral width or the width due to beam divergence which limits the bandwidth of the laser emission. Instantaneous spectral narrowing is found to be proportional to the square root of the time elapsed after the laser onset when a Fabry-Perot etalon or grating is used. When a prism is set in the laser cavity the instantaneous narrowing is proportional to time.

  12. Constancy of spectral-line bisectors

    International Nuclear Information System (INIS)

    Gray, D.F.

    1983-01-01

    Bisectors of spectral line profiles in cool stars indicate the strength of convection in the photospheres of these objects. The present investigation is concerned with the feasibility of studying time variations in line bisectors, the reality of apparent line-to-line differences within the same stellar spectrum, and bisector differences between stars of identical spectral types. The differences considered pertain to the shape of the bisector. The material used in the investigation was acquired at the McDonald Observatory using a 1728 diode Reticon array at the coudefocus of the 2.1-m telescope. Observed bisector errors are discussed. It is established that different lines in the same star show significantly different bisectors. The observed error bands are shown by the shaded regions. The slope and curvature are unique for each case

  13. Spectral solution of the inverse Mie problem

    Science.gov (United States)

    Romanov, Andrey V.; Konokhova, Anastasiya I.; Yastrebova, Ekaterina S.; Gilev, Konstantin V.; Strokotov, Dmitry I.; Chernyshev, Andrei V.; Maltsev, Valeri P.; Yurkin, Maxim A.

    2017-10-01

    We developed a fast method to determine size and refractive index of homogeneous spheres from the power Fourier spectrum of their light-scattering patterns (LSPs), measured with the scanning flow cytometer. Specifically, we used two spectral parameters: the location of the non-zero peak and zero-frequency amplitude, and numerically inverted the map from the space of particle characteristics (size and refractive index) to the space of spectral parameters. The latter parameters can be reliably resolved only for particle size parameter greater than 11, and the inversion is unique only in the limited range of refractive index with upper limit between 1.1 and 1.25 (relative to the medium) depending on the size parameter and particular definition of uniqueness. The developed method was tested on two experimental samples, milk fat globules and spherized red blood cells, and resulted in accuracy not worse than the reference method based on the least-square fit of the LSP with the Mie theory. Moreover, for particles with significant deviation from the spherical shape the spectral method was much closer to the Mie-fit result than the estimated uncertainty of the latter. The spectral method also showed adequate results for synthetic LSPs of spheroids with aspect ratios up to 1.4. Overall, we present a general framework, which can be used to construct an inverse algorithm for any other experimental signals.

  14. Spectral and electronic measurements of solar radiation

    International Nuclear Information System (INIS)

    Suzuki, Mamoru; Hanyu, Mitsuhiro

    1977-01-01

    The spectral data of solar radiation are necessary if detailed discussion is intended in relation to the utilization of solar energy. Since those data have not been fully prepared so far, a measuring equipment developed in Electro-technical Laboratory to obtain those data is described. The laboratory is now continuing the measurement at the wavelength of 0.3 μm to 1.1 μm. The equipment employs the system to always calibrate with the standard light source, it can measure both the direct light of the sun only and the sun light including sky light, and it enables to obtain the value based on the secondary standard of spectral illumination intensity established by the laboratory. The solar spectral irradiance is determined with the current readings of photomultiplier in the standard light source and the sun-light measurements at a wavelength and with the spectral illumination intensity from the standard light source. In order to practice such measurement many times at various wavelengths, control of the equipment, data collection, computation, drawing and listing are performed by a microcomputer. As an example, the data on Sept. 10, 1976, are shown comparing the graphs at three different hours. It can be well observed that the transmissivity attenuates with shorter wavelength, and the transmissivity in near infra-red region changes greatly due to the absorption of radiation by water vapour. (Wakatsuki, Y.)

  15. Aftereffects of Spectrally Similar and Dissimilar Spectral Motion Adaptors in the Tritone Paradox

    Directory of Open Access Journals (Sweden)

    Stephanie Malek

    2018-05-01

    Full Text Available Shepard tones consist of octave-spaced components, whose amplitudes are generated under a fixed bell-shaped spectral envelope. They are well defined in pitch chroma, but generate octave confusions that in turn can produce ambiguities in the perceived relative pitch heights when their chromas are exactly a tritone apart (the tritone paradox. This study examined the effects of tonal context on relative pitch height judgments using adaptor sequences followed by target sequences (pairs of Shepard tones of different chromas separated by a tritone. Listeners judged whether the second target Shepard tone was higher or lower than the first. Adaptor sequences consisted of rising or falling scales (43 s at the beginning of each block, 4 s before each target sequence. Two sets of Shepard tones were used for adaptors and targets that were generated under spectral envelopes centered at either A3 (220 Hz and C6 (1,046 Hz. Pitch direction judgments (rising vs. falling to spectrally consistent (A3–A3, C6–C6 and inconsistent (A3–C6, C6–A3 adaptor-target combinations were studied. Large significant contrastive aftereffects (0.08–0.21 change in fraction of pitch direction responses were only found for the Shepard tones that were judged as higher in the control condition (judgments about the target sequences without adaptor sequences for the consistent adaptor-target conditions (A3–A3, C6–C6. The experiments rule out explanations based on non-sensory decision making processes. Possible explanations in terms of perceptual aftereffects caused by adaptation in central auditory frequency-motion detectors are discussed.

  16. A comparison of EEG spectral entropy with conventional quantitative ...

    African Journals Online (AJOL)

    A comparison of EEG spectral entropy with conventional quantitative EEG at varying depths of sevoflurane anaesthesia. PR Bartel, FJ Smith, PJ Becker. Abstract. Background and Aim: Recently an electroencephalographic (EEG) spectral entropy module (M-ENTROPY) for an anaesthetic monitor has become commercially ...

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

    Science.gov (United States)

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

    2015-04-01

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

  18. The spectral volume method as applied to transport problems

    International Nuclear Information System (INIS)

    McClarren, Ryan G.

    2011-01-01

    We present a new spatial discretization for transport problems: the spectral volume method. This method, rst developed by Wang for computational fluid dynamics, divides each computational cell into several sub-cells and enforces particle balance on each of these sub-cells. Also, these sub-cells are used to build a polynomial reconstruction in the cell. The idea of dividing cells into many cells is a generalization of the simple corner balance and other similar schemes. The spectral volume method preserves particle conservation and preserves the asymptotic diffusion limit. We present results from the method on two transport problems in slab geometry using discrete ordinates and second through sixth order spectral volume schemes. The numerical results demonstrate the accuracy and preservation of the diffusion limit of the spectral volume method. Future work will explore possible bene ts of the scheme for high-performance computing and for resolving diffusive boundary layers. (author)

  19. Spectral characteristics of seismic noise using data of Kazakhstan monitoring stations

    International Nuclear Information System (INIS)

    Mikhajlova, N.N.; Komarov, I.I.

    2006-01-01

    Spectral specifications of seismic noise research for PS23-Makanchi, Karatau, Akbulak, AS057-Borovoye and new three-component station AS059-Aktyubinsk was done. Spectral noise density models were obtained for day and night time and spectral density values variation. Noise close to low-level universal noise model is peculiar for all stations, which provides their high efficiency while seismic monitoring. Noise parameters dependence on seismic receivers installation conditions was investigated separately. Based on three stations (Makanchi, Borovoye, and Aktyubinsk), spectral density change features are shown after borehole equipment installation. (author)

  20. Visual Method for Spectral Energy Distribution Calculation of ...

    Indian Academy of Sciences (India)

    Abstract. In this work, we propose to use 'The Geometer's Sketchpad' to the fitting of a spectral energy distribution of blazar based on three effective spectral indices, αRO, αOX, and αRX and the flux density in the radio band. It can make us to see the fitting in detail with both the peak frequency and peak luminosity given ...

  1. Generalized spectral radius and its max algebra version

    Czech Academy of Sciences Publication Activity Database

    Müller, Vladimír; Peperko, A.

    2013-01-01

    Roč. 439, č. 4 (2013), s. 1006-1016 ISSN 0024-3795 R&D Projects: GA ČR GA201/09/0473; GA AV ČR IAA100190903 Institutional support: RVO:67985840 Keywords : generalized spectral radius * joint spectral radius * Berger-Wang formula Subject RIV: BA - General Mathematics Impact factor: 0.983, year: 2013 http://www.sciencedirect.com/science/article/pii/S0024379512007380

  2. Spectral theories for linear differential equations

    International Nuclear Information System (INIS)

    Sell, G.R.

    1976-01-01

    The use of spectral analysis in the study of linear differential equations with constant coefficients is not only a fundamental technique but also leads to far-reaching consequences in describing the qualitative behaviour of the solutions. The spectral analysis, via the Jordan canonical form, will not only lead to a representation theorem for a basis of solutions, but will also give a rather precise statement of the (exponential) growth rates of various solutions. Various attempts have been made to extend this analysis to linear differential equations with time-varying coefficients. The most complete such extensions is the Floquet theory for equations with periodic coefficients. For time-varying linear differential equations with aperiodic coefficients several authors have attempted to ''extend'' the Foquet theory. The precise meaning of such an extension is itself a problem, and we present here several attempts in this direction that are related to the general problem of extending the spectral analysis of equations with constant coefficients. The main purpose of this paper is to introduce some problems of current research. The primary problem we shall examine occurs in the context of linear differential equations with almost periodic coefficients. We call it ''the Floquet problem''. (author)

  3. Asymptotics of the spectral gap for the interchange process on large hypercubes

    International Nuclear Information System (INIS)

    Starr, Shannon; Conomos, Matthew P

    2011-01-01

    We consider the interchange process (IP) on the d-dimensional, discrete hypercube of side-length n. Specifically, we compare the spectral gap of the IP to the spectral gap of the random walk (RW) on the same graph. We prove that the two spectral gaps are asymptotically equivalent, in the limit n→∞. This result gives further supporting evidence for a conjecture of Aldous, that the spectral gap of the IP equals the spectral gap of the RW on all finite graphs. Our proof is based on an argument invented by Handjani and Jungreis, who proved Aldous's conjecture for all trees

  4. Spectral radiative property control method based on filling solution

    International Nuclear Information System (INIS)

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

    2014-01-01

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

  5. Hyper-spectral frequency selection for the classification of vegetation diseases

    OpenAIRE

    Dijkstra, Klaas; van de Loosdrecht, Jaap; Schomaker, Lambert; Wiering, Marco

    2017-01-01

    Reducing the use of pesticides by early visual detection of diseases in precision agriculture is important. Because of the color similarity between potato-plant diseases, narrow band hyper-spectral imaging is required. Payload constraints on unmanned aerial vehicles require reduc- tion of spectral bands. Therefore, we present a methodology for per-patch classification combined with hyper-spectral band selection. In controlled experiments performed on a set of individual leaves, we measure the...

  6. Evidence of across-channel processing for spectral-ripple discrimination in cochlear implant listeners a

    Science.gov (United States)

    Ho Won, Jong; Jones, Gary L.; Drennan, Ward R.; Jameyson, Elyse M.; Rubinstein, Jay T.

    2011-01-01

    Spectral-ripple discrimination has been used widely for psychoacoustical studies in normal-hearing, hearing-impaired, and cochlear implant listeners. The present study investigated the perceptual mechanism for spectral-ripple discrimination in cochlear implant listeners. The main goal of this study was to determine whether cochlear implant listeners use a local intensity cue or global spectral shape for spectral-ripple discrimination. The effect of electrode separation on spectral-ripple discrimination was also evaluated. Results showed that it is highly unlikely that cochlear implant listeners depend on a local intensity cue for spectral-ripple discrimination. A phenomenological model of spectral-ripple discrimination, as an “ideal observer,” showed that a perceptual mechanism based on discrimination of a single intensity difference cannot account for performance of cochlear implant listeners. Spectral modulation depth and electrode separation were found to significantly affect spectral-ripple discrimination. The evidence supports the hypothesis that spectral-ripple discrimination involves integrating information from multiple channels. PMID:21973363

  7. Applicability of spectral indices on thickness identification of oil slick

    Science.gov (United States)

    Niu, Yanfei; Shen, Yonglin; Chen, Qihao; Liu, Xiuguo

    2016-10-01

    Hyperspectral remote sensing technology has played a vital role in the identification and monitoring of oil spill events, and amount of spectral indices have been developed. In this paper, the applicability of six frequently-used indices is analyzed, and a combination of spectral indices in aids of support vector machine (SVM) algorithm is used to identify the oil slicks and corresponding thickness. The six spectral indices are spectral rotation (SR), spectral absorption depth (HI), band ratio of blue and green (BG), band ratio of BG and shortwave infrared index (BGN), 555nm and 645nm normalized by the blue band index (NB) and spectral slope (ND). The experimental study is conducted in the Gulf of Mexico oil spill zone, with Airborne Visible Infrared Imaging Spectrometer (AVIRIS) hyperspectral imagery captured in May 17, 2010. The results show that SR index is the best in all six indices, which can effectively distinguish the thickness of the oil slick and identify it from seawater; HI index and ND index can obviously distinguish oil slick thickness; BG, BGN and NB are more suitable to identify oil slick from seawater. With the comparison among different kernel functions of SVM, the classify accuracy show that the polynomial and RBF kernel functions have the best effect on the separation of oil slick thickness and the relatively pure seawater. The applicability of spectral indices of oil slick and the method of oil film thickness identification will in aids of oil/gas exploration and oil spill monitoring.

  8. Novel spectral features of nanoelectromechanical systems

    KAUST Repository

    Tahir, M.

    2014-02-17

    Electron transport through a quantum dot or single molecule coupled to a quantum oscillator is studied by the Keldysh nonequilibrium Green\\'s function formalism to obtain insight into the quantum dynamics of the electronic and oscillator degrees of freedom. We tune the electronic level of the quantum dot by a gate voltage, where the leads are kept at zero temperature. Due to the nonequilibrium distribution of the electrons in the quantum dot, the spectral function becomes a function of the gate voltage. Novel spectral features are identified for the ground and excited states of nanomechanical oscillators that can be used to enhance the measurement sensitivity.

  9. Stability estimates for hp spectral element methods for general ...

    Indian Academy of Sciences (India)

    We establish basic stability estimates for a non-conforming ℎ- spectral element method which allows for simultaneous mesh refinement and variable polynomial degree. The spectral element functions are non-conforming if the boundary conditions are Dirichlet. For problems with mixed boundary conditions they are ...

  10. Spectral Efficiency Analysis for Multicarrier Based 4G Systems

    DEFF Research Database (Denmark)

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

    2006-01-01

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

  11. HARLIE 3-D Aerosol Backscatter and Wind Profile Measurements During Recent Field Experiments: Background Noise Reduction with a Fabry-Perot Etalon Filter in the HARLIE System

    Science.gov (United States)

    Lee, Sangwoo; Miller, David O.; Schwemmer, Geary; Wilkerson, Thomas D.; Andrus, Ionio; Egbert, Cameron; Anderson, Mark; Starr, David OC. (Technical Monitor)

    2002-01-01

    Background noise reduction of War signals is one of the most important factors in achieving better signal to noise ratio and precise atmospheric data from Mar measurements. Fahey Perot etalons have been used in several lidar systems as narrow band pass filters in the reduction of scattered sunlight. An slalom with spectral bandwidth, (Delta)v=0.23/cm, free spectral range, FSR=6.7/cm, and diameter, d=24mm was installed in a fiber coupled box which included a 500 pm bandwidth interference Filter. The slalom box couples the telescope and detector with 200 pm core fibers and 21 mm focal length collimators. The angular magnification is M=48. The etalon box was inserted into the Holographic Airborne Rotating Lidar Instrument Experiment (HARLIE) system and tested during the HARGLO-2 intercomparison campaign conducted in November 2001 at Wallops Island, Virginia. This paper presents the preliminary test results of the slalom and a complete analysis will be presented at the conference.

  12. Spectral confocal reflection microscopy using a white light source

    Science.gov (United States)

    Booth, M.; Juškaitis, R.; Wilson, T.

    2008-08-01

    We present a reflection confocal microscope incorporating a white light supercontinuum source and spectral detection. The microscope provides images resolved spatially in three-dimensions, in addition to spectral resolution covering the wavelength range 450-650nm. Images and reflection spectra of artificial and natural specimens are presented, showing features that are not normally revealed in conventional microscopes or confocal microscopes using discrete line lasers. The specimens include thin film structures on semiconductor chips, iridescent structures in Papilio blumei butterfly scales, nacre from abalone shells and opal gemstones. Quantitative size and refractive index measurements of transparent beads are derived from spectral interference bands.

  13. ORMEC: a three-dimensional MHD spectral inverse equilibrium code

    International Nuclear Information System (INIS)

    Hirshman, S.P.; Hogan, J.T.

    1986-02-01

    The Oak Ridge Moments Equilibrium Code (ORMEC) is an efficient computer code that has been developed to calculate three-dimensional MHD equilibria using the inverse spectral method. The fixed boundary formulation, which is based on a variational principle for the spectral coefficients (moments) of the cylindrical coordinates R and Z, is described and compared with the finite difference code BETA developed by Bauer, Betancourt, and Garabedian. Calculations for the Heliotron, Wendelstein VIIA, and Advanced Toroidal Facility (ATF) configurations are performed to establish the accuracy and mesh convergence properties for the spectral method. 16 refs., 13 figs

  14. Spectral Efficiency of OCDMA Systems With Coherent Pulsed Sources

    Science.gov (United States)

    Rochette, Martin; Rusch, Leslie A.

    2005-03-01

    We present a model to evaluate the upper limit of the spectral efficiency of optical code-division multiple-access (OCDMA) systems with coherent sources. Phase-encoded and direct-sequence OCDMA systems are evaluated using this model. The results show that a spectral efficiency of 2.24x10^-2 b/s.Hz can be achieved with a maximum bit error rate of 10^-10 in these systems of the number of users. This result demonstrates that the maximum spectral efficiency of OCDMA systems with coherent sources is at least a factor of 5 higher than OCDMA systems with incoherent sources.

  15. Some threshold spectral problems of Schroedinger operators

    International Nuclear Information System (INIS)

    Jia, X.

    2009-01-01

    This Ph.D. thesis deals with some spectral problems of the Schroedinger operators. We first consider the semi-classical limit of the number of bound states of unique two-cluster N-body Schroedinger operator. Then we use Dirichlet-Neumann bracket to get semi-classical limit of Riesz means of the discrete eigenvalues of N-body Schroedinger operator. The effective potential of N-body Schroedinger operator with Coulomb potential is also considered and we find that the effective potential has critical decay at infinity. Thus, the Schroedinger operator with critical potential is studied in this thesis. We study the coupling constant threshold of Schroedinger operator with critical potential and the asymptotic expansion of resolvent of Schroedinger operator with critical potential. We use that expansion to study low-energy asymptotics of derivative of spectral shift function for perturbation with critical decay. After that, we use this result and the known result for high-energy asymptotic expansion of spectral shift function to obtain the Levinson theorem. (author)

  16. CMB spectral distortions as solutions to the Boltzmann equations

    Energy Technology Data Exchange (ETDEWEB)

    Ota, Atsuhisa, E-mail: a.ota@th.phys.titech.ac.jp [Department of Physics, Tokyo Institute of Technology, Tokyo 152-8551 (Japan)

    2017-01-01

    We propose to re-interpret the cosmic microwave background spectral distortions as solutions to the Boltzmann equation. This approach makes it possible to solve the second order Boltzmann equation explicitly, with the spectral y distortion and the momentum independent second order temperature perturbation, while generation of μ distortion cannot be explained even at second order in this framework. We also extend our method to higher order Boltzmann equations systematically and find new type spectral distortions, assuming that the collision term is linear in the photon distribution functions, namely, in the Thomson scattering limit. As an example, we concretely construct solutions to the cubic order Boltzmann equation and show that the equations are closed with additional three parameters composed of a cubic order temperature perturbation and two cubic order spectral distortions. The linear Sunyaev-Zel'dovich effect whose momentum dependence is different from the usual y distortion is also discussed in the presence of the next leading order Kompaneets terms, and we show that higher order spectral distortions are also generated as a result of the diffusion process in a framework of higher order Boltzmann equations. The method may be applicable to a wider class of problems and has potential to give a general prescription to non-equilibrium physics.

  17. Acquisition and visualization techniques for narrow spectral color imaging.

    Science.gov (United States)

    Neumann, László; García, Rafael; Basa, János; Hegedüs, Ramón

    2013-06-01

    This paper introduces a new approach in narrow-band imaging (NBI). Existing NBI techniques generate images by selecting discrete bands over the full visible spectrum or an even wider spectral range. In contrast, here we perform the sampling with filters covering a tight spectral window. This image acquisition method, named narrow spectral imaging, can be particularly useful when optical information is only available within a narrow spectral window, such as in the case of deep-water transmittance, which constitutes the principal motivation of this work. In this study we demonstrate the potential of the proposed photographic technique on nonunderwater scenes recorded under controlled conditions. To this end three multilayer narrow bandpass filters were employed, which transmit at 440, 456, and 470 nm bluish wavelengths, respectively. Since the differences among the images captured in such a narrow spectral window can be extremely small, both image acquisition and visualization require a novel approach. First, high-bit-depth images were acquired with multilayer narrow-band filters either placed in front of the illumination or mounted on the camera lens. Second, a color-mapping method is proposed, using which the input data can be transformed onto the entire display color gamut with a continuous and perceptually nearly uniform mapping, while ensuring optimally high information content for human perception.

  18. Perceptual sensitivity to spectral properties of earlier sounds during speech categorization.

    Science.gov (United States)

    Stilp, Christian E; Assgari, Ashley A

    2018-02-28

    Speech perception is heavily influenced by surrounding sounds. When spectral properties differ between earlier (context) and later (target) sounds, this can produce spectral contrast effects (SCEs) that bias perception of later sounds. For example, when context sounds have more energy in low-F 1 frequency regions, listeners report more high-F 1 responses to a target vowel, and vice versa. SCEs have been reported using various approaches for a wide range of stimuli, but most often, large spectral peaks were added to the context to bias speech categorization. This obscures the lower limit of perceptual sensitivity to spectral properties of earlier sounds, i.e., when SCEs begin to bias speech categorization. Listeners categorized vowels (/ɪ/-/ɛ/, Experiment 1) or consonants (/d/-/g/, Experiment 2) following a context sentence with little spectral amplification (+1 to +4 dB) in frequency regions known to produce SCEs. In both experiments, +3 and +4 dB amplification in key frequency regions of the context produced SCEs, but lesser amplification was insufficient to bias performance. This establishes a lower limit of perceptual sensitivity where spectral differences across sounds can bias subsequent speech categorization. These results are consistent with proposed adaptation-based mechanisms that potentially underlie SCEs in auditory perception. Recent sounds can change what speech sounds we hear later. This can occur when the average frequency composition of earlier sounds differs from that of later sounds, biasing how they are perceived. These "spectral contrast effects" are widely observed when sounds' frequency compositions differ substantially. We reveal the lower limit of these effects, as +3 dB amplification of key frequency regions in earlier sounds was enough to bias categorization of the following vowel or consonant sound. Speech categorization being biased by very small spectral differences across sounds suggests that spectral contrast effects occur

  19. On the area spectral efficiency improvement of heterogeneous network by exploiting the integration of macro-femto cellular networks

    KAUST Repository

    Shakir, Muhammad

    2012-06-01

    Heterogeneous networks are an attractive means of expanding mobile network capacity. A heterogeneous network is typically composed of multiple radio access technologies (RATs) where the base stations are transmitting with variable power. In this paper, we consider a Heterogeneous network where we complement the macrocell network with low-power low-cost user deployed nodes, such as femtocell base stations to increase the mean achievable capacity of the system. In this context, we integrate macro-femto cellular networks and derive the area spectral efficiency of the proposed two tier Heterogeneous network. We consider the deployment of femtocell base stations around the edge of the macrocell such that this configuration is referred to as femto-on-edge (FOE) configuration. Moreover, FOE configuration mandates reduction in intercell interference due to the mobile users which are located around the edge of the macrocell since these femtocell base stations are low-power nodes which has significantly lower transmission power than macrocell base stations. We present a mathematical analysis to calculate the instantaneous carrier to interference ratio (CIR) of the desired mobile user in macro and femto cellular networks and determine the total area spectral efficiency of the Heterogeneous network. Details of the simulation processes are included to support the analysis and show the efficacy of the proposed deployment. It has been shown that the proposed setup of the Heterogeneous network offers higher area spectral efficiency which aims to fulfill the expected demand of the future mobile users. © 2012 IEEE.

  20. Spectral design flexibility of LED brings better life

    Science.gov (United States)

    Ou, Haiyan; Corell, Dennis; Ou, Yiyu; Poulsen, Peter B.; Dam-Hansen, Carsten; Petersen, Paul-Michael

    2012-03-01

    Light-emitting diodes (LEDs) are penetrating into the huge market of general lighting because they are energy saving and environmentally friendly. The big advantage of LED light sources, compared to traditional incandescent lamps and fluorescent light tubes, is the flexible spectral design to make white light using different color mixing schemes. The spectral design flexibility of white LED light sources will promote them for novel applications to improve the life quality of human beings. As an initial exploration to make use of the spectral design flexibility, we present an example: 'no blue' white LED light source for sufferers of disease Porphyria. An LED light source prototype, made of high brightness commercial LEDs applying an optical filter, was tested by a patient suffering from Porphyria. Preliminary results have shown that the sufferer could withstand the light source for much longer time than the standard light source. At last future perspectives on spectral design flexibility of LED light sources improving human being's life will be discussed, with focus on the light and health. The good health is ensured by the spectrum optimized so that vital hormones (melatonin and serotonin) are produced during times when they support human daily rhythm.