Kulatilake, P.H.S.W.; Shou, G.; Huang, T.H.
1996-04-01
Most of the natural rock joint surface profiles do not belong to the self similar fractal category. In general, roughness profiles of rock joints consist of non-stationary and stationary components. At the simplest level, only one parameter is sufficient to quantify non-stationary joint roughness. The average inclination angle I, along with the direction considered for the joint surface, is suggested to capture the non-stationary roughness. It is shown that even though the fractal dimension D is a useful parameter, it alone is insufficient to quantify the stationary roughness of non-self similar profiles.
Spectral line parameters including line shapes in the 2ν3 Q branch of 12CH4
NASA Astrophysics Data System (ADS)
Devi, V. Malathy; Benner, D. Chris; Sung, Keeyoon; Brown, Linda R.; Crawford, Timothy J.; Yu, Shanshan; Smith, Mary Ann H.; Mantz, Arlan W.; Boudon, Vincent; Ismail, Syed
2016-07-01
In this study, we report the first experimental measurements of spectral line shape parameters (self- and air-broadened Lorentz half-widths, pressure-shifts, and line mixing (via off-diagonal relaxation matrix elements) coefficients and their temperature dependences, where appropriate) for transitions in the 2ν3 Q branch manifolds, Q(11)-Q(1) of methane (12CH4), in the 5996.5-6007-cm-1 region. The analysis included 23 high-resolution, high signal-to-noise laboratory absorption spectra recorded with the Bruker IFS-125HR Fourier transform spectrometer (FTS) at JPL. The experimental data were obtained using 12C-enriched 12CH4 and dilute mixtures of 12CH4 in dry air in the 130-296 K range using a room-temperature long path absorption cell and, two custom-built coolable cells. In the analysis, an interactive multispectrum fitting software was employed where all the 23 spectra (11 self-broadened and 12 air-broadened) were fit simultaneously. By carefully applying reasonable constraints to the parameters for severely blended lines, we were able to determine a self-consistent set of broadening, shift and line mixing (relaxation matrix coefficients) parameters for CH4-CH4 and CH4-air collisions. In the majority of cases, a quadratic speed dependence parameter common for all transitions in each Q(J) manifold was determined. However, temperature dependences of the Q branch line mixing parameter could not be determined from the present data. Since no other experimental line shape measurements have been reported for this Q-branch, the present results are compared to available values in the HITRAN2012 database.
NASA Technical Reports Server (NTRS)
Devi, V. Malathy; Benner, D. Chris; Smith, M. A. H.; Mantz, A. W.; Sung, K.; Brown, L. R.; Predoi-Cross, A.
2012-01-01
Temperature dependences of pressure-broadened half-width and pressure-induced shift coefficients along with accurate positions and intensities have been determined for transitions in the 2<--0 band of C-12 O-16 from analyzing high-resolution and high signal-to-noise spectra recorded with two different Fourier transform spectrometers. A total of 28 spectra, 16 self-broadened and 12 air-broadened, recorded using high- purity (greater than or equal to 99.5% C-12-enriched) CO samples and CO diluted with dry air(research grade) at different temperatures and pressures, were analyzed simultaneously to maximize the accuracy of the retrieved parameters. The sample temperatures ranged from 150 to 298K and the total pressures varied between 5 and 700 Torr. A multispectrum nonlinear least squares spectrum fitting technique was used to adjust the rovibrational constants (G, B, D, etc.) and intensity parameters (including Herman-Wallis coefficients), rather than determining individual line positions and intensities. Self-and air-broadened Lorentz half-width coefficients, their temperature dependence exponents, self- and air-pressure-induced shift coefficients, their temperature dependences, self- and air-line mixing coefficients, their temperature dependences and speed dependence have been retrieved from the analysis. Speed-dependent line shapes with line mixing employing off-diagonal relaxation matrix element formalism were needed to minimize the fit residuals. This study presents a precise and complete set of spectral line parameters that consistently reproduce the spectrum of carbon monoxide over terrestrial atmospheric conditions.
Malathy Devi, V.; Benner, D. C.; Rinsland, C.P.; Smith, M.A.H.; Sams, Robert L.; Blake, Thomas A.; Flaud, Jean Marie; Sung, Keeyoon; Brown, L.R.; Mantz, A. W.
2010-11-01
Ethane is a prominent contributor to the spectrum of Titan, particularly in the region of the v9 band at 12μm. A multispectrum nonlinear least squares fitting program was applied to laboratory spectra of ethane to measure accurate positions, absolute intensities, N2- and selfbroadened half- width coefficients and their temperature dependences for a large number transitions. These measurements include several pQ and rQ sub-bands (and other sub-bands such as pP, rR) in the v9 fundamental band of 12C2H6 centered near 822 cm-1. Positions were measured for 2958 transitions and intensities for 3771 transitions. N2- and self-broadened half-width coefficients were determined for over 1700 transitions while temperature dependence exponents were retrieved for over 1350 of those transitions. Of these, many measurements (mostly line positions and intensities) belong to the v9+v4-v4 hot band, v9+2v4-2v4 hot band, 13C12CH6 v9 band and unidentified transitions. Forty-three high resolution (0.0016-0.005 cm-1) infrared laboratory absorption spectra recorded at temperatures between 148 and 298 K were fitted simultaneously to retrieve these parameters. Forty-one of these spectra were obtained in the temperature range of 211-298 K using the Bruker IFS 120HR interferometer located at the Pacific Northwest National Laboratory (PNNL) in Richland, Washington. Two additional spectra at 148 K were recorded using a new temperature stabilized cryogenic cell designed to work inside the sample compartment of the high resolution Bruker IFS 125HR interferometer of the Jet Propulsion Laboratory (JPL) in Pasadena California. The specialized cooling cell developed at Connecticut College and capable of achieving gas sample temperatures down to 70 K with a temperature stability and uniformity of better than ±0.05 K was employed to record the 148 K spectra. Constraints to intensity ratios, doublet separations, half-width coefficients and their temperature dependence exponents were required to
NASA Astrophysics Data System (ADS)
Weigand, M.; Kemna, A.
2016-06-01
Spectral induced polarization (SIP) data are commonly analysed using phenomenological models. Among these models the Cole-Cole (CC) model is the most popular choice to describe the strength and frequency dependence of distinct polarization peaks in the data. More flexibility regarding the shape of the spectrum is provided by decomposition schemes. Here the spectral response is decomposed into individual responses of a chosen elementary relaxation model, mathematically acting as kernel in the involved integral, based on a broad range of relaxation times. A frequently used kernel function is the Debye model, but also the CC model with some other a priorly specified frequency dispersion (e.g. Warburg model) has been proposed as kernel in the decomposition. The different decomposition approaches in use, also including conductivity and resistivity formulations, pose the question to which degree the integral spectral parameters typically derived from the obtained relaxation time distribution are biased by the approach itself. Based on synthetic SIP data sampled from an ideal CC response, we here investigate how the two most important integral output parameters deviate from the corresponding CC input parameters. We find that the total chargeability may be underestimated by up to 80 per cent and the mean relaxation time may be off by up to three orders of magnitude relative to the original values, depending on the frequency dispersion of the analysed spectrum and the proximity of its peak to the frequency range limits considered in the decomposition. We conclude that a quantitative comparison of SIP parameters across different studies, or the adoption of parameter relationships from other studies, for example when transferring laboratory results to the field, is only possible on the basis of a consistent spectral analysis procedure. This is particularly important when comparing effective CC parameters with spectral parameters derived from decomposition results.
NASA Astrophysics Data System (ADS)
Malathy Devi, V.; Benner, D. Chris; Rinsland, C. P.; Smith, M. A. H.; Sams, R. L.; Blake, T. A.; Flaud, Jean-Marie; Sung, Keeyoon; Brown, L. R.; Mantz, A. W.
2010-04-01
Ethane is a prominent contributor to the spectrum of Titan, particularly in the region of the nu9 band at 12 micron. A multispectrum nonlinear least squares fitting program was applied to laboratory spectra of ethane to measure accurate positions, absolute intensities, N2- and self-broadened half width coefficients and their temperature dependences for a large number transitions. These measurements include several PQ and RQ sub-bands (and other sub bands such as PP, RR) in the nu9 fundamental band of 12C2H6 centered near 822 cm-1. Positions and intensities were measured for more than 1750 transitions. N2- and self-broadened half width coefficients were measured for over 1450 transitions while the temperature dependence exponents were determined for 1330 transitions. About 1900 additional measurements (mostly line positions and intensities) belonging to the nu9+nu4-nu4 hot band, 13C12CH6 nu9 band and over 500 unidentified transitions were also made in the fitted intervals. Forty-three high resolution (0.0016-0.003 cm-1) infrared laboratory absorption spectra recorded at temperatures between 150 and 298 K were fitted simultaneously in retrieving these parameters. Forty-one of these spectra were recorded in the temperature range of 211-298 K using the Bruker IFS 120HR interferometer located at the Pacific Northwest National Laboratory (PNNL) in Richland, Washington. Two additional spectra at 150 K were obtained using the high resolution Bruker IFS 125HR interferometer of the Jet Propulsion Laboratory (JPL) in Pasadena, California. A specialized cooling cell capable of achieving temperatures down to 70 K was employed to record the 150 K spectra. Constraints pertaining to intensity ratios, doublet separations, half width coefficients and their temperature dependence exponents were written in determining these parameters for each of the two torsional split components. Similar to N2- and self-broadened half width coefficients, their temperature dependence exponents were
Vargas, Asticio; Mar Sánchez-López, María del; García-Martínez, Pascuala; Arias, Julia; Moreno, Ignacio
2014-01-21
Multiple-beam Fabry-Perot (FP) interferences occur in liquid crystal retarders (LCR) devoid of an antireflective coating. In this work, a highly accurate method to obtain the spectral retardance of such devices is presented. On the basis of a simple model of the LCR that includes FP effects and by using a voltage transfer function, we show how the FP features in the transmission spectrum can be used to accurately retrieve the ordinary and extraordinary spectral phase delays, and the voltage dependence of the latter. As a consequence, the modulation characteristics of the device are fully determined with high accuracy by means of a few off-state physical parameters which are wavelength-dependent, and a single voltage transfer function that is valid within the spectral range of characterization.
Spectral vegetation indexes and the remote sensing of biophysical parameters
NASA Technical Reports Server (NTRS)
Huemmrich, Karl F.; Goward, Samuel N.
1992-01-01
Combinations of remotely sensed data from different spectral bands have been combined into spectral vegetation indexes (SVIs) and used to determine biophysical parameters. The characteristics of two-band SVIs made up of visible and near-infrared reflectances are examined. Two canopy reflectance models, a turbid media model and a geometrical model, are used to study the effects of different canopy structures on the measurement of leaf area index and the fraction of photosynthetically intercepted active radiation.
Estimation of nonlinear pilot model parameters including time delay.
NASA Technical Reports Server (NTRS)
Schiess, J. R.; Roland, V. R.; Wells, W. R.
1972-01-01
Investigation of the feasibility of using a Kalman filter estimator for the identification of unknown parameters in nonlinear dynamic systems with a time delay. The problem considered is the application of estimation theory to determine the parameters of a family of pilot models containing delayed states. In particular, the pilot-plant dynamics are described by differential-difference equations of the retarded type. The pilot delay, included as one of the unknown parameters to be determined, is kept in pure form as opposed to the Pade approximations generally used for these systems. Problem areas associated with processing real pilot response data are included in the discussion.
Spectral parameter power series representation for Hill's discriminant
Khmelnytskaya, K.V.; Rosu, H.C.
2010-11-15
We establish a series representation of the Hill discriminant based on the spectral parameter power series (SPPS) recently introduced by Kravchenko. We also show the invariance of the Hill discriminant under a Darboux transformation and employing the Mathieu case the feasibility of this type of series for numerical calculations of the eigenspectrum.
Atmospheric parameters, spectral indexes and their relation to CPV spectral performance
NASA Astrophysics Data System (ADS)
Núñez, Rubén; Antón, Ignacio; Askins, Steve; Sala, Gabriel
2014-09-01
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.
Atmospheric parameters, spectral indexes and their relation to CPV spectral performance
Núñez, Rubén Antón, Ignacio Askins, Steve Sala, Gabriel
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.
Estimation of Wheat Agronomic Parameters using New Spectral Indices
Jin, Xiu-liang; Diao, Wan-ying; Xiao, Chun-hua; Wang, Fang-yong; Chen, Bing; Wang, Ke-ru; Li, Shao-kun
2013-01-01
Crop agronomic parameters (leaf area index (LAI), nitrogen (N) uptake, total chlorophyll (Chl) content ) are very important for the prediction of crop growth. The objective of this experiment was to investigate whether the wheat LAI, N uptake, and total Chl content could be accurately predicted using spectral indices collected at different stages of wheat growth. Firstly, the product of the optimized soil-adjusted vegetation index and wheat biomass dry weight (OSAVI×BDW) were used to estimate LAI, N uptake, and total Chl content; secondly, BDW was replaced by spectral indices to establish new spectral indices (OSAVI×OSAVI, OSAVI×SIPI, OSAVI×CIred edge, OSAVI×CIgreen mode and OSAVI×EVI2); finally, we used the new spectral indices for estimating LAI, N uptake, and total Chl content. The results showed that the new spectral indices could be used to accurately estimate LAI, N uptake, and total Chl content. The highest R2 and the lowest RMSEs were 0.711 and 0.78 (OSAVI×EVI2), 0.785 and 3.98 g/m2 (OSAVI×CIred edge) and 0.846 and 0.65 g/m2 (OSAVI×CIred edge) for LAI, nitrogen uptake and total Chl content, respectively. The new spectral indices performed better than the OSAVI alone, and the problems of a lack of sensitivity at earlier growth stages and saturation at later growth stages, which are typically associated with the OSAVI, were improved. The overall results indicated that this new spectral indices provided the best approximation for the estimation of agronomic indices for all growth stages of wheat. PMID:24023639
Models of Spectral Galaxy Evolution including the effects of Dust
NASA Astrophysics Data System (ADS)
Möller, C. S.; Fritze-v. Alvensleben, U.; Fricke, K. J.
To analyse the effects of dust to the UV emission in various galaxy types we present our evolutionary synthesis models which includes dust absorption in a chemically consistent way. The time and redshift evolution of the extinction is based on the evolution of the gas content and metallicity. Comparing our model SED's with templates from Kennicutt's and Kinney et al.'s atlas we show the detailed agreement with integrated spectra of galaxies and point out the importance of aperture effects. We are able to predict the UV fluxes for different galaxy types. Combined with a cosmological model we show the differences in the evolutionary and k-corrections comparing models with and without dust.
Optimizing spectral CT parameters for material classification tasks.
Rigie, D S; La Rivière, P J
2016-06-21
In this work, we propose a framework for optimizing spectral CT imaging parameters and hardware design with regard to material classification tasks. Compared with conventional CT, many more parameters must be considered when designing spectral CT systems and protocols. These choices will impact material classification performance in a non-obvious, task-dependent way with direct implications for radiation dose reduction. In light of this, we adapt Hotelling Observer formalisms typically applied to signal detection tasks to the spectral CT, material-classification problem. The result is a rapidly computable metric that makes it possible to sweep out many system configurations, generating parameter optimization curves (POC's) that can be used to select optimal settings. The proposed model avoids restrictive assumptions about the basis-material decomposition (e.g. linearity) and incorporates signal uncertainty with a stochastic object model. This technique is demonstrated on dual-kVp and photon-counting systems for two different, clinically motivated material classification tasks (kidney stone classification and plaque removal). We show that the POC's predicted with the proposed analytic model agree well with those derived from computationally intensive numerical simulation studies. PMID:27227430
Optimizing spectral CT parameters for material classification tasks
NASA Astrophysics Data System (ADS)
Rigie, D. S.; La Rivière, P. J.
2016-06-01
In this work, we propose a framework for optimizing spectral CT imaging parameters and hardware design with regard to material classification tasks. Compared with conventional CT, many more parameters must be considered when designing spectral CT systems and protocols. These choices will impact material classification performance in a non-obvious, task-dependent way with direct implications for radiation dose reduction. In light of this, we adapt Hotelling Observer formalisms typically applied to signal detection tasks to the spectral CT, material-classification problem. The result is a rapidly computable metric that makes it possible to sweep out many system configurations, generating parameter optimization curves (POC’s) that can be used to select optimal settings. The proposed model avoids restrictive assumptions about the basis-material decomposition (e.g. linearity) and incorporates signal uncertainty with a stochastic object model. This technique is demonstrated on dual-kVp and photon-counting systems for two different, clinically motivated material classification tasks (kidney stone classification and plaque removal). We show that the POC’s predicted with the proposed analytic model agree well with those derived from computationally intensive numerical simulation studies.
Augmenting Forest Stand Parameters using Landsat TM Spectral Images
NASA Astrophysics Data System (ADS)
Reuveni, Y.; Dahan, E.; Anker, Y.; Sprintsin, M.
2015-12-01
Forest stand parameters, such as diameter at breast height (DBH), tree height (H), or volume per hectare (V), are imperative for forest resources assessment. Traditional inventory of forest stand parameters, usually based on fieldwork, is often difficult, time-consuming, and expensive, to conduct in large areas. Therefore, estimating forest stand parameters in large areas using traditional inventory approach augmented by satellites data has a significant implication for sustainable forest management and natural resources efficiency. However, obtaining suitable satellite image data for such purpose is a challenging task mainly because of insignificant knowledge between the forest stand parameters and satellite spectral response relationships. Here, we present the use of Landsat Thematic Mapper (TM) spectral responses data for augmenting forest stand parameter obtained from fieldwork at the Lahav Forest, in the Israeli Northern Negev. A new algorithm was developed in order to use all eight TM band when calculating the linear combination which correlates the most to each one of the forest stand parameters. Each linear combination is obtained first for local area inside the entire studied grid and is then fitted using a simple linear polynomial curve to the known forest stand parameter. Once the relationship between the two is characterized by a linear polynomial equation, the TM linear combination local area data is translated to the same equivalent area of the chosen forest stand parameter. At last, we interpolate the entire TM grid using a higher order polynomial fit applied to all the augmented local area combined together to attain full coverage of the desired forest stand parameter.
Stark Broadening Parameters for Neutral Oxygen Spectral Lines
NASA Astrophysics Data System (ADS)
Alonizan, N.; Qindeel, R.; Nessib, N. Ben; Sahal-Bréchot, S.; Dimitrijević, Milan S.
2015-12-01
Stark broadening parameters for nine neutral oxygen (O I) lines have been determined within the impact approximation and the semiclassical perturbation method. The atomic data have been taken from the TOPbase and NIST atomic databases. The electron and proton Stark widths and shifts and ion broadening parameter values for these O I lines have been calculated for electron density of 10 16 cm -3 and for 4 different electron temperatures in the range of 5000 K to 40000 K. These Stark broadening parameters are compared with our previous results (Ben Nessib, N. et al. 1996, Physica Scripta, 54, 603-613), where we calculated Stark broadening parameters for only four O I spectral lines and where Stark widths and shifts were compared with experimental and theoretical data available in the literature. In the present paper, we have also compared our results with the Griem's book (Griem, H. R. 1974, Spectral line broadening by plasmas) and VALD (Ryabchikova, T. et al. 2015, Physica Scripta, 90, 054005) values.
Bayesian parameter estimation in spectral quantitative photoacoustic tomography
NASA Astrophysics Data System (ADS)
Pulkkinen, Aki; Cox, Ben T.; Arridge, Simon R.; Kaipio, Jari P.; Tarvainen, Tanja
2016-03-01
Photoacoustic tomography (PAT) is an imaging technique combining strong contrast of optical imaging to high spatial resolution of ultrasound imaging. These strengths are achieved via photoacoustic effect, where a spatial absorption of light pulse is converted into a measurable propagating ultrasound wave. The method is seen as a potential tool for small animal imaging, pre-clinical investigations, study of blood vessels and vasculature, as well as for cancer imaging. The goal in PAT is to form an image of the absorbed optical energy density field via acoustic inverse problem approaches from the measured ultrasound data. Quantitative PAT (QPAT) proceeds from these images and forms quantitative estimates of the optical properties of the target. This optical inverse problem of QPAT is illposed. To alleviate the issue, spectral QPAT (SQPAT) utilizes PAT data formed at multiple optical wavelengths simultaneously with optical parameter models of tissue to form quantitative estimates of the parameters of interest. In this work, the inverse problem of SQPAT is investigated. Light propagation is modelled using the diffusion equation. Optical absorption is described with chromophore concentration weighted sum of known chromophore absorption spectra. Scattering is described by Mie scattering theory with an exponential power law. In the inverse problem, the spatially varying unknown parameters of interest are the chromophore concentrations, the Mie scattering parameters (power law factor and the exponent), and Gruneisen parameter. The inverse problem is approached with a Bayesian method. It is numerically demonstrated, that estimation of all parameters of interest is possible with the approach.
C -parameter distribution at N3LL' including power corrections
NASA Astrophysics Data System (ADS)
Hoang, André H.; Kolodrubetz, Daniel W.; Mateu, Vicent; Stewart, Iain W.
2015-05-01
We compute the e+e- C -parameter distribution using the soft-collinear effective theory with a resummation to next-to-next-to-next-to-leading-log prime accuracy of the most singular partonic terms. This includes the known fixed-order QCD results up to O (αs3), a numerical determination of the two-loop nonlogarithmic term of the soft function, and all logarithmic terms in the jet and soft functions up to three loops. Our result holds for C in the peak, tail, and far tail regions. Additionally, we treat hadronization effects using a field theoretic nonperturbative soft function, with moments Ωn. To eliminate an O (ΛQCD) renormalon ambiguity in the soft function, we switch from the MS ¯ to a short distance "Rgap" scheme to define the leading power correction parameter Ω1. We show how to simultaneously account for running effects in Ω1 due to renormalon subtractions and hadron-mass effects, enabling power correction universality between C -parameter and thrust to be tested in our setup. We discuss in detail the impact of resummation and renormalon subtractions on the convergence. In the relevant fit region for αs(mZ) and Ω1, the perturbative uncertainty in our cross section is ≃ 2.5 % at Q =mZ.
C -parameter distribution at N 3 LL ' including power corrections
Hoang, André H.; Kolodrubetz, Daniel W.; Mateu, Vicent; Stewart, Iain W.
2015-05-15
We compute the e⁺e⁻ C-parameter distribution using the soft-collinear effective theory with a resummation to next-to-next-to-next-to-leading-log prime accuracy of the most singular partonic terms. This includes the known fixed-order QCD results up to O(α3s), a numerical determination of the two-loop nonlogarithmic term of the soft function, and all logarithmic terms in the jet and soft functions up to three loops. Our result holds for C in the peak, tail, and far tail regions. Additionally, we treat hadronization effects using a field theoretic nonperturbative soft function, with moments Ωn. To eliminate an O(ΛQCD) renormalon ambiguity in the soft function, we switchmore » from the MS¯ to a short distance “Rgap” scheme to define the leading power correction parameter Ω1. We show how to simultaneously account for running effects in Ω1 due to renormalon subtractions and hadron-mass effects, enabling power correction universality between C-parameter and thrust to be tested in our setup. We discuss in detail the impact of resummation and renormalon subtractions on the convergence. In the relevant fit region for αs(mZ) and Ω1, the perturbative uncertainty in our cross section is ≅ 2.5% at Q=mZ.« less
Mercer's spectral decomposition for the characterization of thermal parameters
NASA Astrophysics Data System (ADS)
Ahusborde, E.; Azaïez, M.; Belgacem, F. Ben; Palomo Del Barrio, E.
2015-08-01
We investigate a tractable Singular Value Decomposition (SVD) method used in thermography for the characterization of thermal parameters. The inverse problem to solve is based on the model of transient heat transfer. The most significant advantage is the transformation of the dynamic identification problem into a steady identification equation. The time dependence is accounted for by the SVD in a performing way. We lay down a mathematical foundation well fitted to this approach, which relies on the spectral expansion of Mercer kernels. This enables us to shed more light on most of its important features. Given its potentialities, the analysis we propose here might help users understanding the way the SVD algorithm, or the TSVD, its truncated version, operate in the thermal parameters estimation and why it is relevant and attractive. When useful, the study is complemented by some analytical and numerical illustrations realized within MATLAB's code.
A Sight on the Variation of Spectral Parameters in GRBs
Hafizi, Mimoza; Boci, Sonila
2010-01-21
Gamma ray bursts (GRBs) are high energy photons detected during a short interval of time. They are signs of the most energetic events in the universe. Photons detected show a non thermal spectrum, very well described by the peak energy and two smoothly connected power laws with different slopes or indices. This spectrum is named Band spectrum and serves actually as the most important source of information on their physical origin. It characterizes not only the overall emission, but also the instantaneous one, found in small successive intervals of time during the event. The time-resolved spectra show an obvious evolution in energy, which is generally accepted and supported by several arguments. There is also some evidence in measuring a kind of evolution in slope parameters, which would be considered as a serious source of information for the physical mechanism. In this work we try to examine the limit in observation bands, which we suspect as a reason for the apparent variation in time of spectral indices. Our work is based on a numeric and certified code. We simulate GRBs assuming synchrotron emission in the internal shocks model. For each time-resolved spectrum we find spectral parameters based on the Band function.
Informed spectral analysis: audio signal parameter estimation using side information
NASA Astrophysics Data System (ADS)
Fourer, Dominique; Marchand, Sylvain
2013-12-01
Parametric models are of great interest for representing and manipulating sounds. However, the quality of the resulting signals depends on the precision of the parameters. When the signals are available, these parameters can be estimated, but the presence of noise decreases the resulting precision of the estimation. Furthermore, the Cramér-Rao bound shows the minimal error reachable with the best estimator, which can be insufficient for demanding applications. These limitations can be overcome by using the coding approach which consists in directly transmitting the parameters with the best precision using the minimal bitrate. However, this approach does not take advantage of the information provided by the estimation from the signal and may require a larger bitrate and a loss of compatibility with existing file formats. The purpose of this article is to propose a compromised approach, called the 'informed approach,' which combines analysis with (coded) side information in order to increase the precision of parameter estimation using a lower bitrate than pure coding approaches, the audio signal being known. Thus, the analysis problem is presented in a coder/decoder configuration where the side information is computed and inaudibly embedded into the mixture signal at the coder. At the decoder, the extra information is extracted and is used to assist the analysis process. This study proposes applying this approach to audio spectral analysis using sinusoidal modeling which is a well-known model with practical applications and where theoretical bounds have been calculated. This work aims at uncovering new approaches for audio quality-based applications. It provides a solution for challenging problems like active listening of music, source separation, and realistic sound transformations.
Investigation into Spectral Parameters as they Impact CPV Module Performance
Muller, M.; Marion, B.; Kurtz, S.; Rodriguez, J.
2011-03-01
The CPV industry is well aware that performance of triple junction cells depends on spectral conditions but there is a lack of data quantifying this spectral dependence at the module level. This paper explores the impact of precipitable water vapor, aerosol optical depth (AOD), and optical air mass on multiple CPV module technologies on-sun in Golden, CO.
Accuracy of the atmospheric parameters determination in FGK stars based on spectral fitting
NASA Astrophysics Data System (ADS)
Mashonkina, Lyudmila
2015-08-01
We perform an extensive testing of the accuracy of atmospheric parameters determination in FGK stars based on the spectral fitting procedure SME (Spectroscopy Made Easy). Our set of stars consists of 13 objects, including the Sun, in temperature range 5000-6600 K and metallicity range -1.4 to +0.4. For these stars the parameters derived by means of interferometry are known. For each star we use spectra obtained with different echelle spectrographs (42000 <= R <= 110000) and different signal-to-noise ratios. We also test how the values of the derived parameters depend on the spectral regions used in the fitting procedure. We tested three different constraints on the spectral masks; four regions of 100 A, each, 4485-4590, 5100-5200, 5600-5700, and 6100-6200 A, the same regions plus Halpha and Hbeta, and the mask employed by Valenti & Fischer (2005). We propose a new method for estimating the uncertainties of the free parameters in SME, based on the fit residuals, partial derivatives and data uncertainties. To construct the distribution for a given free parameter (Teff, log g, etc.) we estimate the change required to match the observations in every pixel involved in the fit. The main difficulty in estimating uncertainties is a non-Gaussian shape of the resulting distribution. This difficulty is alleviated by constructing a cumulative distribution. For stars in the 5700-6600 K temperature range the closest agreement with the effective temperatures derived by interferometry is achieved when the spectral fitting includes the Halpha and Hbeta lines, while for cooler stars the choice of the mask does not effect the results. The derived values of atmospheric parameters do not strongly depend on the spectral resolution and S/N ratio, while the uncertainty both in temperature and surface gravity grows with the effective temperature never being smaller than 50 K in Teff and 0.1 in log g, for typical S/N = 150-200. Better accuracy Delta Teff = 20-30 K and Delta log g = 0
Thermodynamic and cloud parameter retrieval using infrared spectral data
NASA Technical Reports Server (NTRS)
Zhou, Daniel K.; Smith, William L., Sr.; Liu, Xu; Larar, Allen M.; Huang, Hung-Lung A.; Li, Jun; McGill, Matthew J.; Mango, Stephen A.
2005-01-01
High-resolution infrared radiance spectra obtained from near nadir observations provide atmospheric, surface, and cloud property information. A fast radiative transfer model, including cloud effects, is used for atmospheric profile and cloud parameter retrieval. The retrieval algorithm is presented along with its application to recent field experiment data from the NPOESS Airborne Sounding Testbed - Interferometer (NAST-I). The retrieval accuracy dependence on cloud properties is discussed. It is shown that relatively accurate temperature and moisture retrievals can be achieved below optically thin clouds. For optically thick clouds, accurate temperature and moisture profiles down to cloud top level are obtained. For both optically thin and thick cloud situations, the cloud top height can be retrieved with an accuracy of approximately 1.0 km. Preliminary NAST-I retrieval results from the recent Atlantic-THORPEX Regional Campaign (ATReC) are presented and compared with coincident observations obtained from dropsondes and the nadir-pointing Cloud Physics Lidar (CPL).
Cool stars: spectral library of high-resolution echelle spectra and database of stellar parameters
NASA Astrophysics Data System (ADS)
Montes, D.
2013-05-01
During the last years our group have undertake several high resolution spectroscopic surveys of nearby FGKM stars with different spectrographs (FOCES, SARG, SOFIN, FIES, HERMES). A large number of stars have been already observed and we have already determined spectral types, rotational velocities as well as radial velocities, Lithium abundance and several chromospheric activity indicators. We are working now in a homogeneous determination of the fundamental stellar parameters (T_{eff}, log{g}, ξ and [Fe/H]) and chemical abundances of many elements of all these stars. Some fully reduced spectra in FITS format have been available via ftp and in the {http://www.ucm.es/info/Astrof/invest/actividad/spectra.html}{Worl Wide Web} (Montes et al. 1997, A&AS, 123, 473; Montes et al. 1998, A&AS, 128, 485; and Montes et al. 1999, ApJS, 123, 283) and some particular spectral regions of the echelle spectra are available at VizieR by López-Santiago et al. 2010, A&A, 514, A97. We are now working in made accessible all the spectra of our different surveys in a Virtual Observatory ({http://svo.cab.inta-csic.es/}{VO}) compliant library and database accessible using a common web interface following the standards of the International Virtual Observatory Alliance ({http://www.ivoa.net/}{IVOA}). The spectral library includes F, G, K and M field stars, from dwarfs to giants. The spectral coverage is from 3800 to 10000 Å, with spectral resolution ranging from 40000 to 80000. The database will provide in addition the stellar parameters determined for these spectra using {http://cdsads.u-strasbg.fr/abs/2012arXiv1205.4879T}{StePar} (Tabernero et al. 2012, A&A, 547, A13).
NASA Astrophysics Data System (ADS)
Li, Hao; Ma, Yong; Liang, Kun; Tian, Yong; Wang, Rui
2012-01-01
Wavelet parameters (e.g., wavelet type, level of decomposition) affect the performance of the wavelet denoising algorithm in hyperspectral applications. Current studies select the best wavelet parameters for a single spectral curve by comparing similarity criteria such as spectral angle (SA). However, the method to find the best parameters for a spectral library that contains multiple spectra has not been studied. In this paper, a criterion named normalized spectral angle (NSA) is proposed. By comparing NSA, the best combination of parameters for a spectral library can be selected. Moreover, a fast algorithm based on threshold constraint and machine learning is developed to reduce the time of a full search. After several iterations of learning, the combination of parameters that constantly surpasses a threshold is selected. The experiments proved that by using the NSA criterion, the SA values decreased significantly, and the fast algorithm could save 80% time consumption, while the denoising performance was not obviously impaired.
NASA Astrophysics Data System (ADS)
Wilbert, Stefan; Kleindiek, Stefan; Nouri, Bijan; Geuder, Norbert; Habte, Aron; Schwandt, Marko; Vignola, Frank
2016-05-01
Concentrating solar power projects require accurate direct normal irradiance (DNI) data including uncertainty specifications for plant layout and cost calculations. Ground measured data are necessary to obtain the required level of accuracy and are often obtained with Rotating Shadowband Irradiometers (RSI) that use photodiode pyranometers and correction functions to account for systematic effects. The uncertainty of Si-pyranometers has been investigated, but so far basically empirical studies were published or decisive uncertainty influences had to be estimated based on experience in analytical studies. One of the most crucial estimated influences is the spectral irradiance error because Si-photodiode-pyranometers only detect visible and color infrared radiation and have a spectral response that varies strongly within this wavelength interval. Furthermore, analytic studies did not discuss the role of correction functions and the uncertainty introduced by imperfect shading. In order to further improve the bankability of RSI and Si-pyranometer data, a detailed uncertainty analysis following the Guide to the Expression of Uncertainty in Measurement (GUM) has been carried out. The study defines a method for the derivation of the spectral error and spectral uncertainties and presents quantitative values of the spectral and overall uncertainties. Data from the PSA station in southern Spain was selected for the analysis. Average standard uncertainties for corrected 10 min data of 2 % for global horizontal irradiance (GHI), and 2.9 % for DNI (for GHI and DNI over 300 W/m²) were found for the 2012 yearly dataset when separate GHI and DHI calibration constants were used. Also the uncertainty in 1 min resolution was analyzed. The effect of correction functions is significant. The uncertainties found in this study are consistent with results of previous empirical studies.
Wei, Jing; Ming, Yan-fang; Han, Liu-sheng; Ren, Zhong-liang; Guo, Ya-min
2015-10-01
The traditional mineral mapping methods with remote sensing data, based on spectral reflectance matching techniques, shows low accuracy, for obviously being affected by the image quality, atmospheric and other factors. A new mineral mapping method based on multiple types of spectral characteristic parameters is presented in this paper. Various spectral characteristic parameters are used together to enhanced the stability in the situation of atmosphere and environment background affecting. AVIRIS (Airborne Visible Infrared Imaging Spectrometer) data of Nevada Cuprite are selected to determine the mineral types with this method. Typical mineral spectral data are also obtained from USGS (United States Geological Survey) spectral library to calculate the spectral characteristic parameters. A mineral identification model based on multiple spectral characteristic parameters is built by analyzing the various characteristic parameters, and is applied in the mineral mapping experiment in Cuprite area. The mineral mapping result produced by Clark et al. in 1995 is used to evaluate the effect of this method, results show, that mineral mapping results with this method can obtain a high precision, the overall mineral identification accuracy is 78.96%. PMID:26904833
On Spectral Classification and Astrophysical Parameter Estimation for Galactic Surveys
NASA Astrophysics Data System (ADS)
Re Fiorentin, Paola; Bailer-Jones, Coryn A. L.; Beers, Timothy C.; Zwitter, Tomaž
2008-12-01
We present several strategies that are being developed in order to classify and parameterize individual stars observed by Galactic surveys, and illustrate some results obtained from spectra obtained by the RAdial Velocity Experiment (RAVE) and the Sloan Digital Sky Survey (SDSS/SEGUE). We demonstrate the efficiency of our models for discrete source classification and stellar atmospheric parameter estimation (effective temperature, surface gravity, and metallicity), which use supervised machine learning algorithms along with a principal component analysis front-end compression phase that also enables knowledge discovery.
Statistical Analysis of Spectral Properties and Prosodic Parameters of Emotional Speech
NASA Astrophysics Data System (ADS)
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.
Control of the spectral parameters of vanadate lasers
Sirotkin, A A; Vlasov, V I; Zagumennyi, A I; Zavartsev, Yu D; Kutovoi, S A; Shcherbakov, I A
2014-01-31
It is experimentally established that the luminescence spectra of Nd{sup 3+} ions at the {sup 4}F{sub 3/2} – {sup 4}I{sub 11/2} transition in Nd{sup 3+}:YVO{sub 4}, Nd{sup 3+}:GdVO{sub 4}, Nd{sup 3+}:Gd{sub 1-x}Y{sub x}VO{sub 4}, and Nd{sup 3+}:Sc{sub 1-x}Y{sub x}VO{sub 4} vanadate crystals strongly depend on the recording and polarisation angles with respect to the crystallographic axes. Using these angular dependences of luminescence spectra, it is possible to control the gain coefficient for lasers based on vanadate crystals, create broad gain bands for pico- and femtoseconds lasers, and change radiation wavelengths. Efficient operation of a passively Q-switched laser based on a Nd{sup 3+}:GdVO{sub 4} crystal cut at an angle to the a axis (θ = 25°, ψ = 0) is demonstrated for the first time. (control of laser radiation parameters)
Stellar parameters of early-M dwarfs from ratios of spectral features at optical wavelengths
NASA Astrophysics Data System (ADS)
Maldonado, J.; Affer, L.; Micela, G.; Scandariato, G.; Damasso, M.; Stelzer, B.; Barbieri, M.; Bedin, L. R.; Biazzo, K.; Bignamini, A.; Borsa, F.; Claudi, R. U.; Covino, E.; Desidera, S.; Esposito, M.; Gratton, R.; González Hernández, J. I.; Lanza, A. F.; Maggio, A.; Molinari, E.; Pagano, I.; Perger, M.; Pillitteri, I.; Piotto, G.; Poretti, E.; Prisinzano, L.; Rebolo, R.; Ribas, I.; Shkolnik, E.; Southworth, J.; Sozzetti, A.; Suárez Mascareño, A.
2015-05-01
uncertainties of about 70 K. Eighty-two ratios of pseudo-equivalent widths of features were calibrated to derive spectral types within 0.5 subtypes for stars with spectral types between K7V and M4.5V. We calibrated 696 combinations of the pseudo-equivalent widths of individual features and temperature-sensitive ratios for the stellar metallicity over a metallicity range from -0.54 to +0.24 dex, with estimated uncertainties in the range of 0.07-0.10 dex. We provide our own empirical calibrations for stellar mass, radius, and surface gravity. These parameters depend on the stellar metallicity. For a given effective temperature, lower metallicities predict lower masses and radii as well as higher gravities. Based on data products from observations made with ESO Telescopes at the La Silla Paranal Observatory under programmes ID 072.C-0488(E), 082.C-0718(B), 085.C-0019(A), 180.C-0886(A), 183.C-0437(A), and 191.C-0505(A), as well as data from the Italian Telescopio Nazionale Galileo (TNG) Archive (programmes ID CAT-147, and A27CAT_83).Our computational codes including the full version of Tables 2, 4, and 6 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/577/A132Appendix A is available in electronic form at http://www.aanda.org
NASA Astrophysics Data System (ADS)
Fan, Fenglei; Deng, Yingbin
2014-12-01
Successful retrieval of urban impervious surface area is achieved with remote sensing data using the multiple endmember spectral mixture analysis (MESMA). MESMA is well suited for studying the urban impervious surface area because it allows the number and types of the endmembers to vary on a per-pixel basis, thereby, allowing the control of the large spectral variability. However, MESMA must calculate all potential endmember combinations of each pixel to determine the best-fit one. Therefore, it is a time-consuming and inefficient unmixing technology, especially for hyperspectral images because these images have more complicated endmember categories. Hence, in this paper, we design an improved MESMA (SASD-MESMA: spectral angle and spectral distance MESMA) to enhance the computational efficiency of conventional MESMA, and we validate this new method by analyzing the Hyperion image (Jan-2011) and the field-spectra data of Guangzhou (China). In SASD-MESMA, the parameters of spectral angle (SA) and spectral distance (SD) are used to evaluate the similarity degree between library spectra and image spectra in order to identify the most representative endmember combination for each pixel. Results demonstrate that the SA and SD parameters are useful to reduce misjudgment in selecting candidate endmembers and effective for determining the appropriate endmembers in one pixel. Meanwhile, this research indicates that the proposed SASD-MESMA performs very well in retrieving impervious surface area, forest, grass and soil distributions on the sub-pixel level (the overall root mean square error (RMSE) is 0.15 and the correlation coefficient of determination (R2) is 0.68).
NASA Astrophysics Data System (ADS)
Wang, Qian; Yang, Zhong-Dong; Bi, Yan-Meng
2014-11-01
, the results indicate that sampling ratio should exceed 2 pixels/FWHM to ensure the accuracy of CO2 spectrum. Signal-to-noise ratio is one of the most important parameters of hyper spectral CO2 detectors to ensure the reliability of CO2 signal. SNR requirements of CO2 detector to different detection precisions are explored based on the radiance sensitivity factors. The results show that it is difficult to achieve the SNR to detect 1×10-6-4×10-6 CO2 concentration change in the boundary layer by solar shortwave infrared passive remote sensing, limited by the instrument development at present. However, the instrument SNR to detect 1% change in the CO2 column concentration is attainable. The results of this study are not only conductive to universal applications and guides on developing grating spectrometer, but also helpful to have a better understanding of the complexity of CO2 retrieval.
Complete spectral analysis of the Jackiw-Rebbi model, including its zero mode
NASA Astrophysics Data System (ADS)
Charmchi, F.; Gousheh, S. S.
2014-01-01
In this paper we present a complete and exact spectral analysis of the (1+1)-dimensional model that Jackiw and Rebbi considered to show that the half-integral fermion numbers are possible due to the presence of an isolated self-charge-conjugate zero mode. The model possesses the charge and particle conjugation symmetries. These symmetries mandate the reflection symmetry of the spectrum about the line E=0. We obtain the bound-state energies and wave functions of the fermion in this model using two different methods, analytically and exactly, for every arbitrary choice of the parameters of the kink, i.e. its value at spatial infinity (θ0) and its scale of variations (μ). Then, we plot the bound-state energies of the fermion as a function of θ0. This graph enables us to consider a process of building up the kink from the trivial vacuum. We can then determine the origin and evolution of the bound-state energy levels during this process. We see that the model has a dynamical mass generation process at the first quantized level and the zero-energy fermionic mode responsible for the fractional fermion number, is always present during the construction of the kink and its origin is very peculiar, indeed. We also observe that, as expected, none of the energy levels cross one another. Moreover, we obtain analytically the continuum scattering wave functions of the fermion and then calculate the phase shifts of these wave functions. Using the information contained in the graphs of the phase shifts and the bound states, we show that our phase shifts are consistent with the weak and strong forms of the Levinson theorem. Finally, using the weak form of the Levinson theorem, we confirm that the number of the zero-energy fermionic modes is exactly one.
Quantum integrable models of interacting bosons and classical r-matrices with spectral parameters
NASA Astrophysics Data System (ADS)
Skrypnyk, T.
2015-11-01
Using the technique of classical r-matrices with spectral parameters we construct a general form of quantum Lax operators of interacting boson systems corresponding to an arbitrary simple (or reductive) Lie algebra. We prove quantum integrability of these models in the physically important case of g = gl(n) and "diagonal" in the root basis classical r-matrices. We consider in detail two classes of non-skew-symmetric classical r-matrices with spectral parameters and obtain the corresponding quantum Lax operators and quantum integrable many-boson hamiltonians that generalize Bose-Hubbard dimer hamiltonians.
NASA Astrophysics Data System (ADS)
He, Chao; He, Honghui; Chang, Jintao; Ma, Hui
2016-03-01
Polarization imaging techniques are recognized as potentially powerful tools to detect the structural changes of biological tissues. Meanwhile, spectral features of the scattered light can also provide abundant microstructural information, therefore can be applied in biomedical studies. In this paper, we adopt the polarization reflectance spectral imaging to analyze the microstructural changes of hydrolyzing skeletal muscle tissues. We measure the Mueller matrix, which is a comprehensive description of the polarization properties, of the bovine skeletal muscle samples in different periods of time, and analyze its behavior using the multispectral Mueller matrix transformation (MMT) technique. The experimental results show that for bovine skeletal muscle tissues, the backscattered spectral MMT parameters have different values and variation features at different stages. We can also find the experimental results indicate that the stages of hydrolysis for bovine skeletal muscle samples can be judged by the spectral MMT parameters. The results presented in this work show that combining with the spectral technique, the MMT parameters have the potential to be used as tools for meat quality detection and monitoring.
Line parameters for ozone hot bands in the 4.8-micron spectral region
NASA Technical Reports Server (NTRS)
Camy-Peyret, Claude; Flaud, Jean-Marie; Rinsland, Curtis P.; Smith, Mary Ann H.; Devi, V. Malathy
1990-01-01
Line positions, intensities, and lower-state energies have been calculated for nine hot bands of (O-16)3 in the 4.8-micron spectral region using improved spectroscopic parameters deduced in recent high-resolution laboratory studies. The good quality of the hot-band parameters has been verified through comparisons of line-by-line simulations with 0.005/cm-resolution laboratory spectra of ozone. The present work and the line parameters calculated for the main bands by Pickett et al. (1988) provide a complete update of ozone spectroscopic parameters in the 4.8 micron region.
NASA Technical Reports Server (NTRS)
Howell, Leonard W.; Whitaker, Ann F. (Technical Monitor)
2001-01-01
The maximum likelihood procedure is developed for estimating the three spectral parameters of an assumed broken power law energy spectrum from simulated detector responses and their statistical properties investigated. The estimation procedure is then generalized for application to real cosmic-ray data. To illustrate the procedure and its utility, analytical methods were developed in conjunction with a Monte Carlo simulation to explore the combination of the expected cosmic-ray environment with a generic space-based detector and its planned life cycle, allowing us to explore various detector features and their subsequent influence on estimating the spectral parameters. This study permits instrument developers to make important trade studies in design parameters as a function of the science objectives, which is particularly important for space-based detectors where physical parameters, such as dimension and weight, impose rigorous practical limits to the design envelope.
Zhang, Jinjing; Zhang, Tao
2015-02-15
The parameter-induced stochastic resonance based on spectral entropy (PSRSE) method is introduced for the detection of a very weak signal in the presence of strong noise. The effect of stochastic resonance on the detection is optimized using parameters obtained in spectral entropy analysis. Upon processing employing the PSRSE method, the amplitude of the weak signal is enhanced and the noise power is reduced, so that the frequency of the signal can be estimated with greater precision through spectral analysis. While the improvement in the signal-to-noise ratio is similar to that obtained using the Duffing oscillator algorithm, the computational cost reduces from O(N{sup 2}) to O(N). The PSRSE approach is applied to the frequency measurement of a weak signal made by a vortex flow meter. The results are compared with those obtained applying the Duffing oscillator algorithm.
On-line estimation of myoelectric signal spectral parameters and nonstationarities detection.
D'Alessio, T; Knaflitz, M; Balestra, G; Paggi, S
1993-09-01
In this communication, we present a method for detecting nonstationarities of random time series with an approximately Gaussian distribution of amplitudes. This method is suitable for real time implementation. Here we report some results obtained by applying them to a time series of spectral parameters of surface myoelectric signals, collected during voluntary isometric contractions of human muscles. Moreover, we describe the computerized system that we used to implement our detector of nonstationarity. This system is based on the TMS 320C25 DSP chip and realizes on-line estimation and display of spectral parameters, as well as detection of their nonstationarities, featuring a sampling frequency up to 20 k samples/s. A friendly user interface, fully menu driven, allows the user to select different options during the system's operation by means of hot keys. The accuracy of the system was tested by comparing its estimates with those of an off-line system, previously characterized, which we took as a reference. The estimates of spectral parameters obtained by means of the two systems were always consistent. The on-line stationarity detector was able to recognize rates of variation of the spectral parameters as small as 1%/s during contractions lasting 10-15 s. This sensitivity makes it suitable for clinical application. The set of results herein presented has been selected to highlight the main characteristics of the system. PMID:8288289
NASA Technical Reports Server (NTRS)
Marko, H.
1978-01-01
A general spectral transformation is proposed and described. Its spectrum can be interpreted as a Fourier spectrum or a Laplace spectrum. The laws and functions of the method are discussed in comparison with the known transformations, and a sample application is shown.
Electro-optical parameters in excited states of some spectrally active molecules
NASA Astrophysics Data System (ADS)
Benchea, Andreea Celia; Closca, Valentina; Rusu, Cristina Marcela; Morosanu, Cezarina; Dorohoi, Dana Ortansa
2014-08-01
The spectral shifts measured in different solvents are expressed as functions of the solvent macroscopic parameters. The value of the correlation coefficient multiplying the functions of electric permittivity was determined by statistical means. The correlation coefficient depends on the electric dipole moment of the spectrally active molecules. The electro-optical parameters in the ground state of the solute molecules can be approximated by molecular modeling. The excited state parameters are usually estimated using the results obtained both by HyperChem Programme and solvatochromic study. The importance of this approximate method is that it offers information about of the excited state of solute molecule for which our measuring possibilities are very restrictive. The information about the excited electronic state is affected by the limits in which the theories of liquid solutions are developed. Our results refer to two molecules of vitamins from B class, namely B3 and B6.
NASA Astrophysics Data System (ADS)
Ghezzi, Luan; Dutra-Ferreira, Letícia; Lorenzo-Oliveira, Diego; Porto de Mello, Gustavo F.; Santiago, Basílio X.; De Lee, Nathan; Lee, Brian L.; da Costa, Luiz N.; Maia, Marcio A. G.; Ogando, Ricardo L. C.; Wisniewski, John P.; González Hernández, Jonay I.; Stassun, Keivan G.; Fleming, Scott W.; Schneider, Donald P.; Mahadevan, Suvrath; Cargile, Phillip; Ge, Jian; Pepper, Joshua; Wang, Ji; Paegert, Martin
2014-12-01
Studies of Galactic chemical, and dynamical evolution in the solar neighborhood depend on the availability of precise atmospheric parameters (effective temperature T eff, metallicity [Fe/H], and surface gravity log g) for solar-type stars. Many large-scale spectroscopic surveys operate at low to moderate spectral resolution for efficiency in observing large samples, which makes the stellar characterization difficult due to the high degree of blending of spectral features. Therefore, most surveys employ spectral synthesis, which is a powerful technique, but relies heavily on the completeness and accuracy of atomic line databases and can yield possibly correlated atmospheric parameters. In this work, we use an alternative method based on spectral indices to determine the atmospheric parameters of a sample of nearby FGK dwarfs and subgiants observed by the MARVELS survey at moderate resolving power (R ~ 12,000). To avoid a time-consuming manual analysis, we have developed three codes to automatically normalize the observed spectra, measure the equivalent widths of the indices, and, through a comparison of those with values calculated with predetermined calibrations, estimate the atmospheric parameters of the stars. The calibrations were derived using a sample of 309 stars with precise stellar parameters obtained from the analysis of high-resolution FEROS spectra, permitting the low-resolution equivalent widths to be directly related to the stellar parameters. A validation test of the method was conducted with a sample of 30 MARVELS targets that also have reliable atmospheric parameters derived from the high-resolution spectra and spectroscopic analysis based on the excitation and ionization equilibria method. Our approach was able to recover the parameters within 80 K for T eff, 0.05 dex for [Fe/H], and 0.15 dex for log g, values that are lower than or equal to the typical external uncertainties found between different high-resolution analyses. An additional test was
Ghezzi, Luan; Da Costa, Luiz N.; Maia, Marcio A. G.; Ogando, Ricardo L. C.; Dutra-Ferreira, Letícia; Lorenzo-Oliveira, Diego; Porto de Mello, Gustavo F.; Santiago, Basílio X.; De Lee, Nathan; Lee, Brian L.; Ge, Jian; Wisniewski, John P.; González Hernández, Jonay I.; Stassun, Keivan G.; Cargile, Phillip; Pepper, Joshua; Fleming, Scott W.; Schneider, Donald P.; Mahadevan, Suvrath; Wang, Ji; and others
2014-12-01
Studies of Galactic chemical, and dynamical evolution in the solar neighborhood depend on the availability of precise atmospheric parameters (effective temperature T {sub eff}, metallicity [Fe/H], and surface gravity log g) for solar-type stars. Many large-scale spectroscopic surveys operate at low to moderate spectral resolution for efficiency in observing large samples, which makes the stellar characterization difficult due to the high degree of blending of spectral features. Therefore, most surveys employ spectral synthesis, which is a powerful technique, but relies heavily on the completeness and accuracy of atomic line databases and can yield possibly correlated atmospheric parameters. In this work, we use an alternative method based on spectral indices to determine the atmospheric parameters of a sample of nearby FGK dwarfs and subgiants observed by the MARVELS survey at moderate resolving power (R ∼ 12,000). To avoid a time-consuming manual analysis, we have developed three codes to automatically normalize the observed spectra, measure the equivalent widths of the indices, and, through a comparison of those with values calculated with predetermined calibrations, estimate the atmospheric parameters of the stars. The calibrations were derived using a sample of 309 stars with precise stellar parameters obtained from the analysis of high-resolution FEROS spectra, permitting the low-resolution equivalent widths to be directly related to the stellar parameters. A validation test of the method was conducted with a sample of 30 MARVELS targets that also have reliable atmospheric parameters derived from the high-resolution spectra and spectroscopic analysis based on the excitation and ionization equilibria method. Our approach was able to recover the parameters within 80 K for T {sub eff}, 0.05 dex for [Fe/H], and 0.15 dex for log g, values that are lower than or equal to the typical external uncertainties found between different high-resolution analyses. An
NASA Astrophysics Data System (ADS)
Shaw, A.; Arvidson, R. E.; Wolff, M. J.; Seelos, F. P.; Wiseman, S. M.; Cull, S.
2011-12-01
CRISM (Compact Reconnaissance Imaging Spectrometer for Mars) data were used to retrieve scattering parameters of surfaces traversed by the Opportunity Mars rover, as well as adjacent areas. Our estimates agree with those retrieved by Johnson et al. [2006] using Opportunity's Panoramic Camera data, and we are able to extend estimates of the Hapke single particle scattering albedo and asymmetry parameter (from the one-term Henyey Greenstein single particle phase function) to a greater spectral resolution and spectral range. This analysis allows us to distinguish between surface units that otherwise look relatively uniform spectrally. This work also provides photometric functions essential for converting spectra to a single viewing geometry which will yield more accurate spectral comparisons. Our method involves simultaneously modeling surface and atmospheric contributions, iterating through surface scattering parameters until a Levenberg-Marquardt least squares best fit is achieved. Retrieved single scattering albedos range from 0.42 to 0.57 (0.5663 - 2.2715 micrometers), and retrieved asymmetry parameters range from -0.27 to -0.17 (moderately backscattering). All surfaces become more backscattering with increasing wavelength. Further, the northern and western portions of Victoria crater's ejecta apron are more backscattering than surrounding regions, indicating a change in physical properties. In images taken when the rover traversed this unit, a surface with small ripples and a dense cover of hematitic spherules is apparent, providing agreement with lab experiments by Johnson et al. [2006] showing increased backscattering with the addition of hematitic spherules. The CRISM-derived scattering parameters also show that bedrock-dominated surfaces are less backscattering than soil-covered surfaces.
Analysis of graded-index optical fibers by the spectral parameter power series method
NASA Astrophysics Data System (ADS)
Castillo-Pérez, Raúl; Kravchenko, Vladislav V.; Torba, Sergii M.
2015-02-01
The spectral parameter power series (SPPS) method is a recently introduced technique (Kravchenko 2008 Complex Var. Elliptic Equ. 53 775-89, Kravchenko and Porter 2010 Math. Methods Appl. Sci. 33 459-68) for solving linear differential equations and related spectral problems. In this work we develop an approach based on the SPPS for analysis of graded-index optical fibers. The characteristic equation of the eigenvalue problem for calculation of guided modes is obtained in an analytical form in terms of SPPS. Truncation of the series and consideration in this way of the approximate characteristic equation gives us a simple and efficient numerical method for solving the problem. Comparison with the results obtained by other available techniques reveals clear advantages for the SPPS approach, in particular, with regards to accuracy. Based on the solution of the eigenvalue problem, parameters describing the dispersion are analyzed as well.
Spectral line parameters for the O2 Herzberg I band system
NASA Astrophysics Data System (ADS)
Cann, M. W. P.; Nicholls, R. W.
1991-09-01
Spectral line parameters required for line-by-line spectral synthesis have been calculated for the weak Herzberg I band system of O2. The line locations were calculated with constants from Borrell et al. (1986) and agree closely with these authors' measured wave numbers. Line strengths were calculated using formulas given by Lewis and Gibson (1990), but empirically modified to concur with the relative strengths measured by Herzberg (1952), the only ones found in the literature. Line strengths and line widths are both very uncertain and need to be revised as more information becomes available. Line parameters were calculated for transitions from the nu-double prime = 0, 1, and 2 vibrational levels.
Atmospheric and Fundamental Parameters of Stars in Hubble's Next Generation Spectral Library
NASA Technical Reports Server (NTRS)
Heap, Sally
2010-01-01
Hubble's Next Generation Spectral Library (NGSL) consists of R approximately 1000 spectra of 374 stars of assorted temperature, gravity, and metallicity. We are presently working to determine the atmospheric and fundamental parameters of the stars from the NGSL spectra themselves via full-spectrum fitting of model spectra to the observed (extinction-corrected) spectrum over the full wavelength range, 0.2-1.0 micron. We use two grids of model spectra for this purpose: the very low-resolution spectral grid from Castelli-Kurucz (2004), and the grid from MARCS (2008). Both the observed spectrum and the MARCS spectra are first degraded in resolution to match the very low resolution of the Castelli-Kurucz models, so that our fitting technique is the same for both model grids. We will present our preliminary results with a comparison with those from the Sloan/Segue Stellar Parameter Pipeline, ELODIE, and MILES, etc.
Quantitative spectral domain optical coherence tomography thickness parameters in type II diabetes
Gella, Laxmi; Raman, Rajiv; Sharma, Tarun
2016-01-01
Purpose: To elucidate the changes in retinal thickness and individual layer thickness in subjects with diabetic retinopathy (DR) using spectral domain optical coherence tomography (SDOCT). Materials and Methods: A total of 251 eyes from 170 subjects were included in this study. The study sample was subdivided into nondiabetic subjects; subjects with diabetes but no DR; subjects with mild, moderate, and severe nonproliferative DR (NPDR); and proliferative DR. Various retinal thickness parameters were assessed using SDOCT. Results: The mean age of the study population was 55.34 ± 9.02 years (range: 32–80 years) and 56.6% of the subjects were males. Men had significantly greater central foveal thickness, central subfield thickness, retinal nerve fiber layer thickness, and retinal thickness in all the quadrants of 3 mm and 6 mm zones compared to women (P < 0.001). Superior (293.11 ± 25.46 vs. 285.25 ± 19.17; P = 0.044) and temporal (282.10 ± 25.26 vs. 272.46 ± 16.21; P = 0.011) quadrants showed an increased retinal thickness in any DR group when compared with diabetic subjects without DR. Photoreceptor layer thickness was significantly reduced in diabetic subjects with no DR when compared with nondiabetic subjects and also in cases of severe NPDR when compared with mild and moderate NPDR. Conclusion: Here, we analyze the quantitative retinal thickness parameters in diabetic subjects using SDOCT. Neuronal degenerative changes such as photoreceptor and retinal pigment epithelial thinning in case of DR are also reported. PMID:27013826
Mera-Adasme, Raúl; Sadeghian, Keyarash; Sundholm, Dage; Ochsenfeld, Christian
2014-11-20
Classical force-field parameters of the metal site of metalloproteins usually comprise only the partial charges of the involved atoms, as well as the bond-stretching and bending parameters of the metal-ligand interactions. Although for certain metal ligands such as histidine residues, the torsional motions at the metal site play an important role for the dynamics of the protein, no such terms have been considered to be crucial in the parametrization of the force fields, and they have therefore been omitted in the parametrization. In this work, we have optimized AMBER-compatible force-field parameters for the reduced state of the metal site of copper, zinc superoxide dismutase (SOD1) and assessed the effect of including torsional parameters for the histidine-metal interactions in molecular dynamics simulations. On the basis of the obtained results, we recommend that torsion parameters of the metal site are included when processes at the metal site are investigated or when free-energy calculations are performed. As the torsion parameters mainly affect the structure of the metal site, other kinds of structural studies can be performed without considering the torsional parameters of the metal site. PMID:25410708
NASA Technical Reports Server (NTRS)
Howell, L. W.
2001-01-01
A simple power law model consisting of a single spectral index (alpha-1) is believed to be an adequate description of the galactic cosmic-ray (GCR) proton flux at energies below 10(exp 13) eV, with a transition at knee energy (E(sub k)) to a steeper spectral index alpha-2 > alpha-1 above E(sub k). The maximum likelihood procedure is developed for estimating these three spectral parameters of the broken power law energy spectrum from simulated detector responses. These estimates and their surrounding statistical uncertainty are being used to derive the requirements in energy resolution, calorimeter size, and energy response of a proposed sampling calorimeter for the Advanced Cosmic-ray Composition Experiment for the Space Station (ACCESS). This study thereby permits instrument developers to make important trade studies in design parameters as a function of the science objectives, which is particularly important for space-based detectors where physical parameters, such as dimension and weight, impose rigorous practical limits to the design envelope.
NASA Technical Reports Server (NTRS)
Howell, L. W.; Rose, M. Franklin (Technical Monitor)
2000-01-01
A simple power law model consisting of a single spectral index alpha (sub 1), is believed to be an adequate description of the galactic cosmic ray (GCR) proton flux at energies below 10(exp 13) eV, with a transition at knee energy E(sub k) to a steeper spectral index alpha(sub 2) greater than alpha(sub 1) above E(sub k). The maximum likelihood procedure is developed for estimating these three spectral parameters of the broken power law energy spectrum from simulated detector responses. These estimates and their surrounding statistical uncertainty are being used to derive the requirements in energy resolution, calorimeter size, and energy response of a proposed sampling calorimeter for the Advanced Cosmic ray Composition Experiment for the Space Station (ACCESS). This study thereby permits instrument developers to make important trade studies in design parameters as a function of the science objectives, which is particularly important for space-based detectors where physical parameters, such as dimension and weight, impose rigorous practical limits to the design envelope.
NASA Astrophysics Data System (ADS)
Filippazzo, Joseph C.; Rice, Emily L.; Faherty, Jacqueline; Cruz, Kelle L.; Van Gordon, Mollie M.; Looper, Dagny L.
2015-09-01
We combine optical, near-infrared, and mid-infrared spectra and photometry to construct expanded spectral energy distributions for 145 field age (>500 Myr) and 53 young (lower age estimate <500 Myr) ultracool dwarfs (M6-T9). This range of spectral types includes very low mass stars, brown dwarfs, and planetary mass objects, providing fundamental parameters across both the hydrogen and deuterium burning minimum masses for the largest sample assembled to date. A subsample of 29 objects have well constrained ages as probable members of a nearby young moving group. We use 182 parallaxes and 16 kinematic distances to determine precise bolometric luminosities (Lbol) and radius estimates from evolutionary models give semi-empirical effective temperatures (Teff) for the full range of young and field age late-M, L, and T dwarfs. We construct age-sensitive relationships of luminosity, temperature, and absolute magnitude as functions of spectral type and absolute magnitude to disentangle the effects of degenerate physical parameters such as Teff, surface gravity, and clouds on spectral morphology. We report bolometric corrections in J for both field age and young objects and find differences of up to a magnitude for late-L dwarfs. Our correction in Ks shows a larger dispersion but not necessarily a different relationship for young and field age sequences. We also characterize the NIR-MIR reddening of low gravity L dwarfs and identify a systematically cooler Teff of up to 300 K from field age objects of the same spectral type and 400 K cooler from field age objects of the same MH magnitude.
NASA Technical Reports Server (NTRS)
Howell, Leonard W.
2002-01-01
The method of Maximum Likelihood (ML) is used to estimate the spectral parameters of an assumed broken power law energy spectrum from simulated detector responses. This methodology, which requires the complete specificity of all cosmic-ray detector design parameters, is shown to provide approximately unbiased, minimum variance, and normally distributed spectra information for events detected by an instrument having a wide range of commonly used detector response functions. The ML procedure, coupled with the simulated performance of a proposed space-based detector and its planned life cycle, has proved to be of significant value in the design phase of a new science instrument. The procedure helped make important trade studies in design parameters as a function of the science objectives, which is particularly important for space-based detectors where physical parameters, such as dimension and weight, impose rigorous practical limits to the design envelope. This ML methodology is then generalized to estimate broken power law spectral parameters from real cosmic-ray data sets.
Zhou, Minghao; Meng, Fangang
2015-12-15
Ultrafiltration (UF) can achieve excellent removal of natural organic matter (NOM), but the main challenge for this process is the limited understanding of membrane fouling. The objective of this study is to explore the potential of UV-vis spectroscopic analysis for the detection of membrane fouling caused by humic acids (HA) at different solution chemistries (i.e., calcium ions (Ca(2+)) and pH). In the presence of Ca(2+), several spectral parameters, including the DSlope(325-375) (the slope of the log-transformed absorbance spectra over 325-375 nm), S(275-295) (the slope of the absorption coefficient over 257-295 nm) and S(R) (the ratio of S(275-295) to S(350-400)) of various HA solutions, were correlated with the molecule aggregation and the membrane fouling potential. Interestingly, increased DSlope(325-375) and decreased S(275-295) and S(R) were observed for the HA-Ca(2+) interaction under alkaline conditions (i.e., pH = 9) relative to those in lower pH environments (i.e., pH = 7 or 6), suggesting that spectral parameters were able to predict HA-Ca(2+) interactions under varying pH conditions. The strong correlations between the spectral parameters and the unified membrane fouling index (UMFI) obtained from UF experiments further corroborated that the spectral parameters were able to predict the membrane fouling potential. Moreover, the spectral parameters were also found to well reveal the fouling extent of the mixture of HA and Suwannee River NOM (SRNOM) or the pure SRNOM added with varying calcium concentrations, implying that the spectroscopic analysis was also available for the indication of practical NOM fouling. In addition, the measurement of S(275-295) and S(R) of the permeate solution suggests an increasing proportion of small-molecule HA in the permeate during the UF process. This study not only expands our knowledge of NOM-Ca(2+) aggregates as well as their role in membrane fouling behavior but also provides an approach for the in situ
Speed-dependent spectral line profile including line narrowing and mixing
NASA Astrophysics Data System (ADS)
Kochanov, Victor P.
2016-07-01
A line profile model was developed that accounts for all essential underlying physical mechanisms. The model is based on the quantum-mechanical collision integral kernel calculated for intermolecular interaction potentials ∝r-n with n=3…6 where r is the distance between colliding molecules. It was shown that collisions of molecules with scattering on classical small angles flatten the line profile. The relative flattening reaches 10% for n=3 and has a smaller value, ~2%, for n=6 in conditions of inhomogeneous line broadening. An algebraic expression for the line profile was obtained, which allows processing recorded spectra with preliminary estimation and constraint of some of the profile's parameters.
NASA Astrophysics Data System (ADS)
Benner, D. Chris; Devi, V. Malathy; Nugent, Emily; Brown, Linda R.; Miller, Charles E.; Toth, Robert A.; Sung, Keeyoon
2009-06-01
Room temperature spectra of carbon dioxide were obtained with the Fourier transform spectrometers at the National Solar Observatory's McMath-Pierce telescope and at the Jet Propulsion Laboratory. The multispectrum nonlinear least squares fitting technique is being used to derive accurate spectral line parameters for the strongest CO_2 bands in the 4700-4930 cm^{-1} spectral region. Positions of the spectral lines were constrained to their quantum mechanical relationships, and the rovibrational constants were derived directly from the fit. Similarly, the intensities of the lines within each of the rovibrational bands were constrained to their quantum mechanical relationships, and the band strength and Herman-Wallis coefficients were derived directly from the fit. These constraints even include a pair of interacting bands with the interaction coefficient derived directly using both the positions and intensities of the spectral lines. Room temperature self and air Lorentz halfwidth and pressure induced line shift coefficients are measured for most lines. Constraints upon the positions improve measurement of pressure-induced shifts, and constraints on the intensities improve the measurement of the Lorentz halfwidths. Line mixing and speed dependent line shapes are also required and characterized. D. Chris Benner, C.P. Rinsland, V. Malathy Devi, M.A.H. Smith, and D. Atkins, J. Quant. Spectrosc. Radiat. Transfer 53, 705-721 (1995)
NASA Astrophysics Data System (ADS)
Kaschinski, Cornelius Bernhard
optical emission lines, from which the mass loss rate is determined in case of a purely optical based analysis, depends on the square of the density. A possible clumpiness in the winds would thus lead to an uncertainty in the determination of atmospheric mass loss rates from the strength of such optical recombination lines. Since the mass loss rate is not a free parameter, but is rather a function of the other stellar parameters, this may lead to an uncertainty in the determination of the stellar parameters. We used the improved code to re-evaluate, with respect to the influence of clumping on the appearance of the UV spectra, the optical parameter set determined in an earlier study that employed clumping in its models to achieve fits to the observed optical lines. We found that, with and without clumping, wind strengths and terminal velocities in accordance to their stellar parameters from the optical analysis yield spectra which are incompatible with the optical and UV observations, whereas our self-consistent models achieve good fits to both observations. Moreover, moderate clumping factors are found to have the same order of influence on the optical recombination lines as the density (velocity field) has. During the same study we also derived shock temperatures and ratios of X-ray to bolometric luminosities so as to reproduce the highly ionized O VI line in the Far Ultraviolet Spectroscopic Explorer spectral range. These values agree with those derived for O stars, again confirming the similarity of massive O type CSPN and massive O star atmospheres. Based on the derived shock structures of our sample of CSPNs we investigated the possible influence of shocks on emission line studies from HII regions. Here, tools for the inversion of line ratios into desired physical properties are required and come in the form of diagnostic ratios or diagrams which are based on grids of photoionization models. We calculated such a grid of shock influenced ionizing fluxes from a
[Measurement technology for multi-parameter spectral responsivity of X-ray scintillation crystals].
Li, Rui-hong; Han, Yue-ping; Zhou, Han-chang; Han, Yan
2010-08-01
Aimed at the measurement demand for development of better X-ray scintillation crystals, a photoelectrical detector for integrally test the multi-parameter spectral responsivity of scintillation crystals was developed. The conversion spectrum of the scintillation crystal excited by various X-ray energies under the critical focal length could be measured directly through the spectral output interface by one spectrometer, and the photovoltaic effect voltage of the PIN photodiode could be tested through the voltage output interface by one oscilloscope. Furthermore, the output power of fluorescence was calculated using an equivalent circuit. The measurement results show that the conversion efficiency of the scintillator declined along with the current increase of the X-ray tube while it has weak relation with the change in tube voltage. The experimental results show that the method presented in this paper is helpful for testing the scintillator properties. PMID:20939335
Speed-dependent spectral line profile including line narrowing and mixing
NASA Astrophysics Data System (ADS)
Kochanov, Victor P.
2016-07-01
A line profile model was developed that accounts for all essential underlying physical mechanisms. The model is based on the quantum-mechanical collision integral kernel calculated for intermolecular interaction potentials ∝r-n with n=3…6 where r is the distance between colliding molecules. It was shown that collisions of molecules with scattering on classical small angles flatten the line profile. The relative flattening reaches 10% for n=3 and has a smaller value, ~2%, for n=6 in conditions of inhomogeneous line broadening. An algebraic expression for the line profile was obtained, which allows processing recorded spectra with preliminary estimation and constraint of some of the profile's parameters.
Determination of the parameters of a holographic layer from its spectral characteristics
NASA Astrophysics Data System (ADS)
Kraiskii, A. A.; Kraiskii, A. V.
2016-06-01
Methods for estimating the main parameters of holographic sensors (refractive index modulation depth and hologram thickness) from transmission spectra in the absence of absorption and light scattering are discussed. The consideration is performed for layers oriented parallel to the holographic layer surface under normal light incidence. Direct numerical solution of the problem of light propagation in a periodic nonabsorbing medium is used to study the reflection and transmission spectra of the holographic layer in a wide range of variation in its thickness and the refractive index modulation depth. A classification of the reflection regimes from the holographic layer is proposed (from weak reflection to the photonic crystal regime). A comparison with the results obtained by the coupled-wave analysis is performed, and the limitations of this method at a significant spectral detuning from resonance and under conditions of strong reflection are revealed. It is shown that the main hologram parameters can be estimated from the experimental transmission spectrum of the phase hologram (in the case of strong reflection) based on the spectral dip parameters.
Masiello, Guido; Serio, Carmine
2013-04-10
The problem of simultaneous physical retrieval of surface emissivity, skin temperature, and temperature, water-vapor, and ozone atmospheric profiles from high-spectral-resolution observations in the infrared is formulated according to an inverse problem with multiple regularization parameters. A methodology has been set up, which seeks an effective solution to the inverse problem in a generalized L-curve criterion framework. The a priori information for the surface emissivity is obtained on the basis of laboratory data alone, and that for the atmospheric parameters by climatology or weather forecasts. To ensure that we deal with a problem of fewer unknowns than observations, the dimensionality of the emissivity is reduced through expansion in Fourier series. The main objective of this study is to demonstrate the simultaneous retrieval of emissivity, skin temperature, and atmospheric parameters with a two-dimensional L-curve criterion. The procedure has been demonstrated with spectra observed from the infrared atmospheric sounder interferometer, flying onboard the European Meteorological Operational satellite. To check the quality and reliability of the methodology, we have used spectra recorded over regions characterized by known or stable emissivity. These include sea surface, for which effective emissivity models are known, and arid lands (Sahara and Namib Deserts) that are known to exhibit the characteristic spectral signature of quartz-rich sand. PMID:23670773
NASA Astrophysics Data System (ADS)
Schäfer, Tanja; Nathues, Andreas; Mengel, Kurt; Izawa, Matthew R. M.; Cloutis, Edward A.; Schäfer, Michael; Hoffmann, Martin
2016-02-01
We identified a set of spectral parameters based on Dawn Framing Camera (FC) bandpasses, covering the wavelength range 0.4-1.0 μm, for mineralogical mapping of potential chondritic material and aqueous alteration products on dwarf planet Ceres. Our parameters are inferred from laboratory spectra of well-described and clearly classified carbonaceous chondrites representative for a dark component. We additionally investigated the FC signatures of candidate bright materials including carbonates, sulfates and hydroxide (brucite), which can possibly be exposed on the cerean surface by impact craters or plume activity. Several materials mineralogically related to carbonaceous chondrites, including pure ferromagnesian phyllosilicates, and serpentinites were also investigated. We tested the potential of the derived FC parameters for distinguishing between different carbonaceous chondritic materials, and between other plausible cerean surface materials. We found that the major carbonaceous chondrite groups (CM, CO, CV, CK, and CR) are distinguishable using the FC filter ratios 0.56/0.44 μm and 0.83/0.97 μm. The absorption bands of Fe-bearing phyllosilicates at 0.7 and 0.9 μm in terrestrial samples and CM carbonaceous chondrites can be detected by a combination of FC band parameters using the filters at 0.65, 0.75, 0.83, 0.92 and 0.97 μm. This set of parameters serves as a basis to identify and distinguish different lithologies on the cerean surface by FC multispectral data.
NASA Astrophysics Data System (ADS)
Chen, Jinsong; Hubbard, Susan S.; Williams, Kenneth H.; Flores Orozco, AdriáN.; Kemna, Andreas
2012-05-01
We developed a hierarchical Bayesian model to estimate the spatiotemporal distribution of aqueous geochemical parameters associated with in-situ bioremediation using surface spectral induced polarization (SIP) data and borehole geochemical measurements collected during a bioremediation experiment at a uranium-contaminated site near Rifle, Colorado (USA). The SIP data were first inverted for Cole-Cole parameters, including chargeability, time constant, resistivity at the DC frequency, and dependence factor, at each pixel of two-dimensional grids using a previously developed stochastic method. Correlations between the inverted Cole-Cole parameters and the wellbore-based groundwater chemistry measurements indicative of key metabolic processes within the aquifer (e.g., ferrous iron, sulfate, uranium) were established and used as a basis for petrophysical model development. The developed Bayesian model consists of three levels of statistical submodels: (1) data model, providing links between geochemical and geophysical attributes, (2) process model, describing the spatial and temporal variability of geochemical properties in the subsurface system, and (3) parameter model, describing prior distributions of various parameters and initial conditions. The unknown parameters were estimated using Markov chain Monte Carlo methods. By combining the temporally distributed geochemical data with the spatially distributed geophysical data, we obtained the spatiotemporal distribution of ferrous iron, sulfate, and sulfide, and their associated uncertainty information. The obtained results can be used to assess the efficacy of the bioremediation treatment over space and time and to constrain reactive transport models.
NASA Technical Reports Server (NTRS)
Vukovich, Fred M.; Toll, David L.; Kennard, Ruth L.
1989-01-01
Surface biophysical estimates were derived from analysis of NOAA Advanced Very High Spectral Resolution (AVHRR) spectral data of the Senegalese area of west Africa. The parameters derived were of solar albedo, spectral visible and near-infrared band reflectance, spectral vegetative index, and ground temperature. Wet and dry linked AVHRR scenes from 1981 through 1985 in Senegal were analyzed for a semi-wet southerly site near Tambacounda and a predominantly dry northerly site near Podor. Related problems were studied to convert satellite derived radiance to biophysical estimates of the land surface. Problems studied were associated with sensor miscalibration, atmospheric and aerosol spatial variability, surface anisotropy of reflected radiation, narrow satellite band reflectance to broad solar band conversion, and ground emissivity correction. The middle-infrared reflectance was approximated with a visible AVHRR reflectance for improving solar albedo estimates. In addition, the spectral composition of solar irradiance (direct and diffuse radiation) between major spectral regions (i.e., ultraviolet, visible, near-infrared, and middle-infrared) was found to be insensitive to changes in the clear sky atmospheric optical depth in the narrow band to solar band conversion procedure. Solar albedo derived estimates for both sites were not found to change markedly with significant antecedent precipitation events or correspondingly from increases in green leaf vegetation density. The bright soil/substrate contributed to a high albedo for the dry related scenes, whereas the high internal leaf reflectance in green vegetation canopies in the near-infrared contributed to high solar albedo for the wet related scenes. The relationship between solar albedo and ground temperature was poor, indicating the solar albedo has little control of the ground temperature. The normalized difference vegetation index (NDVI) and the derived visible reflectance were more sensitive to antecedent
Dale, Daniel A.; Helou, George; Magdis, Georgios E.; Armus, Lee; Díaz-Santos, Tanio; Shi, Yong
2014-03-20
A two-parameter semi-empirical model is presented for the spectral energy distributions of galaxies with contributions to their infrared-submillimeter-radio emission from both star formation and accretion disk-powered activity. This model builds upon a previous one-parameter family of models for star-forming galaxies, and includes an update to the mid-infrared emission using an average template obtained from Spitzer Space Telescope observations of normal galaxies. Star-forming/active galactic nucleus (AGN) diagnostics based on polycyclic aromatic hydrocarbon equivalent widths and broadband infrared colors are presented, and example mid-infrared AGN fractional contributions are estimated from model fits to the Great Observatories All-Sky LIRG Survey sample of nearby U/LIRGS and the Five mJy Unbiased Spitzer Extragalactic Survey sample of 24 μm selected sources at redshifts 0 ≲ z ≲ 4.
Mapping Site Response Parameters on Cal Poly Pomona Campus Using the Spectral Ratio Method
NASA Astrophysics Data System (ADS)
HO, K. Y. K.; Polet, J.
2014-12-01
Site characteristics are an important factor in earthquake hazard assessment. To better understand site response differences on a small scale, as well as the seismic hazard of the area, we develop site response parameter maps of Cal Poly Pomona campus. Cal Poly Pomona is located in southern California about 40 km east of Los Angeles, within 50 km of San Andreas Fault. The campus is situated on top of the San Jose Fault. With about twenty two thousand students on campus, it is important to know the site response in this area. To this end, we apply the Horizontal-to-Vertical (H/V) spectral ratio technique, which is an empirical method that can be used in an urban environment with no environmental impact. This well-established method is based on the computation of the ratio of vertical ambient noise ground motion over horizontal ambient noise ground motion as a function of frequency. By applying the spectral ratio method and the criteria from Site Effects Assessment Using Ambient Excitations (SESAME) guidelines, we can determine fundamental frequency and a minimum site amplification factor. We installed broadband seismometers throughout the Cal Poly Pomona campus, with an initial number of about 15 sites. The sites are approximately 50 to 150 meters apart and about two hours of waveforms were recorded at each site. We used the Geopsy software to make measurements of the peak frequency and the amplitude of the main peak from the spectral ratio. These two parameters have been determined to be estimates of fundamental frequency and a minimum site amplification factor, respectively. Based on the geological map from the U.S. Geological Survey (USGS) and our data collected from Cal Poly Pomona campus, our preliminary results suggest that the area of campus that is covered by alluvial fan material tends to have a single significant spectral peak with a fundamental frequency of ~1Hz and a minimum amplification factor of ~3.7. The minimum depth of the surface layer is about 56
NASA Astrophysics Data System (ADS)
Sheinman, O. K.
2015-12-01
Based on ℤ-gradings of semisimple Lie algebras and invariant polynomials on them, we construct hierarchies of Lax equations with a spectral parameter on a Riemann surface and prove the commutativity of the corresponding flows.
Characterizing Woody Vegetation Spectral and Structural Parameters with a 3-D Scene Model
NASA Astrophysics Data System (ADS)
Qin, W.; Yang, L.
2004-05-01
Quantification of structural and biophysical parameters of woody vegetation is of great significance in understanding vegetation condition, dynamics and functionality. Such information over a landscape scale is crucial for global and regional land cover characterization, global carbon-cycle research, forest resource inventories, and fire fuel estimation. While great efforts and progress have been made in mapping general land cover types over large area, at present, the ability to quantify regional woody vegetation structural and biophysical parameters is limited. One approach to address this research issue is through an integration of physically based 3-D scene model with multiangle and multispectral remote sensing data and in-situ measurements. The first step of this work is to model woody vegetation structure and its radiation regime using a physically based 3-D scene model and field data, before a robust operational algorithm can be developed for retrieval of important woody vegetation structural/biophysical parameters. In this study, we use an advanced 3-D scene model recently developed by Qin and Gerstl (2000), based on L-systems and radiosity theories. This 3-D scene model has been successfully applied to semi-arid shrubland to study structure and radiation regime at a regional scale. We apply this 3-D scene model to a more complicated and heterogeneous forest environment dominated by deciduous and coniferous trees. The data used in this study are from a field campaign conducted by NASA in a portion of the Superior National Forest (SNF) near Ely, Minnesota during the summers of 1983 and 1984, and supplement data collected during our revisit to the same area of SNF in summer of 2003. The model is first validated with reflectance measurements at different scales (ground observations, helicopter, aircraft, and satellite). Then its ability to characterize the structural and spectral parameters of the forest scene is evaluated. Based on the results from this study
Heistand, B.E.; Novak, E.F.
1984-04-01
This report documents the work performed to determine the newly assigned concentrations for the spectral gamma-ray borehole calibration models. Thirty-two models, maintained by the US Department of Energy, are included in this study, and are grouped into eight sets of four models each. The eight sets are located at sites across the United States, and are used to calibrate logging instruments. The assignments are based on in-situ logging data to ensure self-consistency in the assigned concentrations, and on laboratory assays of concrete samples from each model to provide traceability to the New Brunswick Laboratory (NBL) standards. 13 references, 7 figures, 17 tables.
Spectral parameter estimation of CAT radar echoes in the presence of fading clutter
NASA Technical Reports Server (NTRS)
Sato, T.; Woodman, R. F.
1980-01-01
The analysis technique and a part of the results obtained from CAT radar echoes from higher troposphere and lower stratosphere are presented. First, the effect of processing distortion caused by the periodogram method using FFT algorithm on the slowly fading ground clutter echo is discussed. It is shown that an extremely narrow clutter spectrum can spill over the entire frequency range if the data are truncated at a tie sorter than their correlation time affecting largely the estimation of the CAT spectrum contribution, especially when the latter is a few tens of dB weaker than the former. A nonlinear least squares fitting procedure is used to parameterize the observed power spectrum in terms of CAT echo power, Doppler shift, spectral width, and the parameters which specify the shape of the clutter component.
NASA Astrophysics Data System (ADS)
Hartmann, J.-M.; Tran, H.; Ngo, N. H.; Landsheere, X.; Chelin, P.; Lu, Y.; Liu, A.-W.; Hu, S.-M.; Gianfrani, L.; Casa, G.; Castrillo, A.; Lepère, M.; Delière, Q.; Dhyne, M.; Fissiaux, L.
2013-01-01
We present a fully ab initio model and calculations of the spectral shapes of absorption lines in a pure molecular gas under conditions where the influences of collisions and of the Doppler effect are significant. Predictions of the time dependence of dipole autocorrelation functions (DACFs) are made for pure CO2 at room temperature using requantized classical molecular dynamics simulations. These are carried, free of any adjusted parameter, on the basis of an accurate anisotropic intermolecular potential. The Fourier-Laplace transforms of these DACFs then yield calculated spectra which are analyzed, as some measured ones, through fits using Voigt line profiles. Comparisons between theory and various experiments not only show that the main line-shape parameters (Lorentz pressure-broadening coefficients) are accurately predicted, but that subtle observed non-Voigt features are also quantitatively reproduced by the model. These successes open renewed perspectives for the understanding of the mechanisms involved (translational-velocity and rotational-state changes and their dependences on the molecular speed) and the quantification of their respective contributions. The proposed model should also be of great help for the test of widely used empirical line-shape models and, if needed, the construction of more physically based ones.
Estimation of the spectral parameter kappa in the region of the Gulf of California, Mexico
NASA Astrophysics Data System (ADS)
Castro, Raúl R.; Ávila-Barrientos, Lenin
2015-10-01
We analyzed records from the Broadband Seismological Network of the Gulf of California (RESBAN) and from stations of the NARS-Baja array, operated by CICESE, Ensenada, Baja California, Mexico, to make estimates of the spectral decay parameter kappa ( κ). This attenuation parameter is important for evaluating the seismic risk and hazard of this region. Thirteen shallow earthquakes with focal depths less than 20 km and magnitudes between 5.1 and 6.6 were selected to calculate κ and the near-site attenuation κ 0. We used three different approaches to estimate κ 0: (a) with individual measurements of κ from vector modulus of three-component spectral amplitudes at different epicentral distances and extrapolating to zero distance to estimate κ 0, (b) with individual measurements using vertical component spectra, and (c) measuring from the high-frequency part of the site transfer function determined calculating the horizontal-to-vertical spectral ratio (HVSR) method. For most stations, the three methods give similar results. At short distances (50-60 km), κ takes values close to 0.04 s at NE76, the station located in the middle of the array. κ increases with distance taking an average value of up to 0.18 s for distances close to 500 km. κ 0 at most sites is close to 0.03 s, except for GUYB (Guaymas) that has a κ 0 = 0.05 s and NE83 (Navolato) with κ 0 = 0.065 s, both stations located in the continent, on the eastern side of the gulf, where the soils are less consolidated. Finally, we analyze if κ 0 correlates with magnitude and back azimuth, and we found that for most stations, κ 0 does not correlate with either one. However, station TOPB, located on basalt, shows a moderate correlation with magnitude, with κ 0 increasing with increasing M W in a short back-azimuth range. We also found that for station NE74, located on soft soil, κ 0 correlates with back azimuth, having lower values for azimuths near 120°.
Spectral action for a one-parameter family of Dirac operators on { SU}{(2)} and {SU}{(3)}
NASA Astrophysics Data System (ADS)
Lai, Alan; Teh, Kevin
2013-02-01
The one-parameter family of Dirac operators containing the Levi-Civita, cubic, and the trivial Dirac operators on a compact Lie group is analyzed. The spectra for the one-parameter family of Dirac Laplacians on SU(2) and SU(3) are computed by considering a diagonally embedded Casimir operator. Then the asymptotic expansions of the spectral actions for SU(2) and SU(3) are computed, using the Poisson summation formula and the two-dimensional Euler-Maclaurin formula, respectively. The inflation potential and slow-roll parameters for the corresponding pure gravity inflationary theory are generated, using the full asymptotic expansion of the spectral action on SU(2).
NASA Astrophysics Data System (ADS)
Tomasella, Lina; Munari, Ulisse; Zwitter, Tomaž
2010-12-01
We present an Echelle+CCD, high signal-to-noise ratio, high-resolution (R = 20,000) spectroscopic atlas of 108 well-known objects representative of the most common types of peculiar and variable stars. The wavelength interval extends from 4600 to 9400 Å and includes the RAVE, Gaia, and HERMES wavelength ranges. Multi-epoch spectra are provided for the majority of the observed stars. A total of 425 spectra of peculiar stars, which were collected during 56 observing nights between 1998 November and 2002 August, are presented. The spectra are given in FITS format and heliocentric wavelengths, with accurate subtraction of both the sky background and the scattered light. Auxiliary material useful for custom applications (telluric dividers, spectrophotometric stars, flat-field tracings) is also provided. The atlas aims to provide a homogeneous database of the spectral appearance of stellar peculiarities, a tool useful both for classification purposes and inter-comparison studies. It could also serve in the planning and development of automated classification algorithms designed for RAVE, Gaia, HERMES, and other large-scale spectral surveys. The spectrum of XX Oph is discussed in some detail as an example of the content of the present atlas.
Tomasella, Lina; Munari, Ulisse; Zwitter, Tomaz
2010-12-15
We present an Echelle+CCD, high signal-to-noise ratio, high-resolution (R = 20,000) spectroscopic atlas of 108 well-known objects representative of the most common types of peculiar and variable stars. The wavelength interval extends from 4600 to 9400 A and includes the RAVE, Gaia, and HERMES wavelength ranges. Multi-epoch spectra are provided for the majority of the observed stars. A total of 425 spectra of peculiar stars, which were collected during 56 observing nights between 1998 November and 2002 August, are presented. The spectra are given in FITS format and heliocentric wavelengths, with accurate subtraction of both the sky background and the scattered light. Auxiliary material useful for custom applications (telluric dividers, spectrophotometric stars, flat-field tracings) is also provided. The atlas aims to provide a homogeneous database of the spectral appearance of stellar peculiarities, a tool useful both for classification purposes and inter-comparison studies. It could also serve in the planning and development of automated classification algorithms designed for RAVE, Gaia, HERMES, and other large-scale spectral surveys. The spectrum of XX Oph is discussed in some detail as an example of the content of the present atlas.
A Recommended Procedure for Estimating the Cosmic Ray Spectral Parameter of a Simple Power Law
NASA Technical Reports Server (NTRS)
Howell, Leonard W.; Rose, M. Franklin (Technical Monitor)
2000-01-01
A simple power law model consisting of a single spectral index a(f(sub i)) is believed to be an adequate description of the galactic cosmic ray (GQ proton flux at energies below 1013 eV. Two procedures for estimating a(f(sub i)), referred as (1) the method of moments, and (2) maximum likelihood, are developed and their statistical performance compared. I concluded that the maximum likelihood procedure attains the most desirable statistical properties and is hence the recommended statistic estimation procedure for estimating a1. The maximum likelihood procedure is then generalized for application to a set of real cosmic ray data and thereby makes this approach applicable to existing cosmic ray data sets. Several other important results, such as the relationship between collecting power and detector energy resolution, as well as inclusion of a non-Gaussian detector response function, are presented. These results have many practical benefits in the design phase of a cosmic ray detector because they permit instrument developers to make important trade studies in design parameters as a function of one of the science objectives, which is particularly important for space-based detectors where physical parameters, such as dimension and weight, impose practical limits to the design envelope.
Taylor, Brian A; Hwang, Ken-Pin; Hazle, John D; Stafford, R Jason
2009-03-01
The authors investigated the performance of the iterative Steiglitz-McBride (SM) algorithm on an autoregressive moving average (ARMA) model of signals from a fast, sparsely sampled, multiecho, chemical shift imaging (CSI) acquisition using simulation, phantom, ex vivo, and in vivo experiments with a focus on its potential usage in magnetic resonance (MR)-guided interventions. The ARMA signal model facilitated a rapid calculation of the chemical shift, apparent spin-spin relaxation time (T2*), and complex amplitudes of a multipeak system from a limited number of echoes (< or equal 16). Numerical simulations of one- and two-peak systems were used to assess the accuracy and uncertainty in the calculated spectral parameters as a function of acquisition and tissue parameters. The measured uncertainties from simulation were compared to the theoretical Cramer-Rao lower bound (CRLB) for the acquisition. Measurements made in phantoms were used to validate the T2* estimates and to validate uncertainty estimates made from the CRLB. We demonstrated application to real-time MR-guided interventions ex vivo by using the technique to monitor a percutaneous ethanol injection into a bovine liver and in vivo to monitor a laser-induced thermal therapy treatment in a canine brain. Simulation results showed that the chemical shift and amplitude uncertainties reached their respective CRLB at a signal-to-noise ratio (SNR) > or =5 for echo train lengths (ETLs) > or =4 using a fixed echo spacing of 3.3 ms. T2* estimates from the signal model possessed higher uncertainties but reached the CRLB at larger SNRs and/or ETLs. Highly accurate estimates for the chemical shift (<0.01 ppm) and amplitude (<1.0%) were obtained with > or =4 echoes and for T2*(<1.0%) with > or =7 echoes. We conclude that, over a reasonable range of SNR, the SM algorithm is a robust estimator of spectral parameters from fast CSI acquisitions that acquire < or =16 echoes for one- and two-peak systems. Preliminary ex vivo
Taylor, Brian A.; Hwang, Ken-Pin; Hazle, John D.; Stafford, R. Jason
2009-01-01
The authors investigated the performance of the iterative Steiglitz–McBride (SM) algorithm on an autoregressive moving average (ARMA) model of signals from a fast, sparsely sampled, multiecho, chemical shift imaging (CSI) acquisition using simulation, phantom, ex vivo, and in vivo experiments with a focus on its potential usage in magnetic resonance (MR)-guided interventions. The ARMA signal model facilitated a rapid calculation of the chemical shift, apparent spin-spin relaxation time (T2*), and complex amplitudes of a multipeak system from a limited number of echoes (≤16). Numerical simulations of one- and two-peak systems were used to assess the accuracy and uncertainty in the calculated spectral parameters as a function of acquisition and tissue parameters. The measured uncertainties from simulation were compared to the theoretical Cramer–Rao lower bound (CRLB) for the acquisition. Measurements made in phantoms were used to validate the T2* estimates and to validate uncertainty estimates made from the CRLB. We demonstrated application to real-time MR-guided interventions ex vivo by using the technique to monitor a percutaneous ethanol injection into a bovine liver and in vivo to monitor a laser-induced thermal therapy treatment in a canine brain. Simulation results showed that the chemical shift and amplitude uncertainties reached their respective CRLB at a signal-to-noise ratio (SNR)≥5 for echo train lengths (ETLs)≥4 using a fixed echo spacing of 3.3 ms. T2* estimates from the signal model possessed higher uncertainties but reached the CRLB at larger SNRs and∕or ETLs. Highly accurate estimates for the chemical shift (<0.01 ppm) and amplitude (<1.0%) were obtained with ≥4 echoes and for T2* (<1.0%) with ≥7 echoes. We conclude that, over a reasonable range of SNR, the SM algorithm is a robust estimator of spectral parameters from fast CSI acquisitions that acquire ≤16 echoes for one- and two-peak systems. Preliminary ex vivo and in vivo
Cloutier, G; Durand, L G; Guardo, R; Sabbah, H N; Stein, P D
1989-08-01
A method is proposed to estimate the bias and variability of eight diagnostic spectral parameters extracted from mitral closing sounds produced by bioprosthetic heart valves. These spectral parameters are: the frequency of the dominant (F1) and second dominant (F2) spectral peaks, the highest frequency of the spectrum found at -3 dB (F-3), -10 dB (F-10) and -20 dB (F-20) below the highest peak, the relative integrated area above -20 dB of the dominant peak (RIA20), the bandwidth at -3 dB of the dominant spectral peak (BW3), and the ratio of F1 divided by BW3 (Q1). The bias and variability of four spectral techniques were obtained by comparing parameters extracted from each technique with the parameters of a spectral "standard." This "standard" consisted of 19 normal mitral sound spectra computed analytically by evaluating the Z transform of a sum of decaying sinusoids on the unit circle. Truncation of the synthesized mitral signals and addition of random noise were used to simulate the physiological characteristics of the closing sounds. Results show that the fast Fourier transform method with rectangular window provides the best estimates of F1 and Q1, that the Steiglitz-McBride method with maximum entropy (pole-zero modeling with four poles and four zeros) can best evaluate F2, F-20, RIA20 and BW3, and that the all-pole modeling with covariance method (16 poles) is best suited to compute F-3. It was also shown that both the all-pole modeling and the Steiglitz-McBride methods can be used to estimate F-10. It is concluded that a single algorithm would not provide the best estimates of all spectral parameters. PMID:2759640
NASA Astrophysics Data System (ADS)
Barseghyan, Diana; Exner, Pavel; Khrabustovskyi, Andrii; Tater, Miloš
2016-04-01
We analyze two-dimensional Schrödinger operators with the potential | {xy}{| }p-λ {({x}2+{y}2)}p/(p+2) where p≥slant 1 and λ ≥slant 0 which exhibit an abrupt change of spectral properties at a critical value of the coupling constant λ. We show that in the supercritical case the spectrum covers the whole real axis. In contrast, for λ below the critical value the spectrum is purely discrete and we establish a Lieb-Thirring-type bound on its moments. In the critical case where the essential spectrum covers the positive halfline while the negative spectrum can only be discrete, we demonstrate numerically the existence of a ground-state eigenvalue.
Improved line parameters for ozone bands in the 10-micron spectral region
NASA Technical Reports Server (NTRS)
Flaud, Jean-Marie; Camy-Peyret, Claude; Rinsland, Curtis P.; Smith, Mary Ann H.; Devi, Malathy V.
1990-01-01
A complete update of spectroscopic line parameters for the 10-micron bands of ozone is reported. The listing contains calculated positions, intensities, lower state energies, and air- and self-broadened halfwidths of more than 53,000 lines. The results have been generated using improved spectroscopic parameters obtained in a number of recent high resolution laboratory studies. A total of eighteen bands of (O-16)3 (sixteen hot bands plus the nu(1) and nu(3) fundamentals) are included along with the nu(1) and nu(3) fundamentals of both (O-16)(O-16)(O-18) and (O-16)(O-18)(O-16). As shown by comparisons of line-by-line simulations with 0.003/cm resolution balloon-borne stratospheric solar spectra, the new parameters greatly improve the accuracy of atmospheric calculations in the 10-micron region, especially for the isotopic (O-16)(O-16)(O-18) and (O-16)(O-18)(O-16) lines.
NASA Astrophysics Data System (ADS)
Ward, A. L.; Draper, K.; Hasan, N.
2010-12-01
Knowledge of spatially variable aquifer hydraulic and sorption parameters is a pre-requisite for an improved understanding of the transport and spreading of sorbing solutes and for the development of effective strategies for remediation. Local-scale estimates of these parameters are often derived from core measurements but are typically not representative of field values. Fields-scale estimates are typically derived from pump and tracer tests but often lack the spatial resolution necessary to deconvolve the effects of fine-scale heterogeneities. Geophysical methods have the potential to bridge this gap both in terms of coverage and resolution, provided meaningful petrophysical relationships can be developed. The objective of this study was to develop a petrophysical relationship between soil textural attributes and the gamma-energy response of natural sediments. Measurements from Hanford’s 300 Area show the best model to be a linear relationship between 232Th concentration and clay content (R2 = 94%). This relationship was used to generate a 3-D distribution of clay mass fraction based on borehole spectral gamma logs. The distribution of clay was then used to predict distributions of permeability, porosity, bubbling pressure, and the pore-size distribution index, all of which are required for predicting variably saturated flow, as well as the specific surface area and cation exchange capacity needed for reactive transport predictions. With this approach, it is possible to obtain reliable estimates of hydraulic properties in zones that could not be characterized by field or laboratory measurements. The spatial distribution of flow properties is consistent with lithologic transitions inferred from geologist’s logs. A preferential flow path, identified from solute and heat tracer experiments and attributed to an erosional incision in the low-permeability Ringold Formation, is also evident. The resulting distributions can be used as a starting model for the
X-ray spectral parameters for a sample of 95 active galactic nuclei
NASA Astrophysics Data System (ADS)
Vasylenko, A. A.; Zhdanov, V. I.; Fedorova, E. V.
2015-12-01
We present a broadband X-ray analysis of a new homogeneous sample of 95 active galactic nuclei (AGN) from the 22-month Swift/BAT all-sky survey. For this sample we treated jointly the X-ray spectra observed by XMM-Newton and INTEGRAL missions for the total spectral range of 0.5-250 keV. Photon index \\varGamma, relative reflection R, equivalent width of Fe K_{α} line EW_{FeK}, hydrogen column density NH, exponential cut-off energy Ec and intrinsic luminosity L_{corr} are determined for all objects of the sample. We investigated correlations \\varGamma-R, EW_{FeK}-L_{corr}, \\varGamma-Ec, EW_{FeK}-NH. Dependence "\\varGamma-R" for Seyfert 1/2 galaxies has been investigated separately. We found that the relative reflection parameter at low power-law indexes for Seyfert 2 galaxies is systematically higher than for Seyfert 1 ones. This can be related to an increasing contribution of the reflected radiation from the gas-dust torus. Our data show that there exists some anticorrelation between EW_{FeK} and L_{corr}, but it is not strong. We have not found statistically significant deviations from the AGN Unified Model.
Measurement of the spectral characteristics and color parameters of flat objects
NASA Astrophysics Data System (ADS)
Gorbunova, Elena V.; Chertov, Aleksandr N.; Lastovskaia, Elena A.; Korotaev, Valery V.; Norko, Vadim E.
2015-02-01
Quality control of different coatings (colorful, paint, marker, safety, etc.) that are applied to the surface of various objects (both metallic and non-metallic) is an important problem. Also, there is a problem of dealing with counterfeit products. So it's necessary to distinguish the fake replicas of marking from the authentic marking of producer. To solve these problems, we propose an automated device (hardware and software complex) for analysis and control of spectral reflection characteristics, albedo and color parameters of extended (up to 150 mm × 150 mm) flat objects. It allows constructing the color image of the object surface as well as its multispectral images in selected regions of the spectrum. Herewith the color of the object surface can be calculated for various standard light sources (A, B, C, D65, E, F2, F7, F11, GE), or to any light source with a predetermined emission spectrum. The paper presents the description of construction and working principles of the proposed hardware and software complex. All color settings calculations correspond to the requirements and recommendations of CIE.
Fischer, Joachim Ernst; Vossmerbaeumer, Urs
2016-01-01
Background. Optical coherence tomography (OCT) allows quantitative analysis of the anterior segment of the eye with a noncontact examination. The aim of this study is to analyze associations of central corneal thickness (CCT) as measured by OCT with ocular and systemic cardiovascular parameters. Methods. A cross-sectional study of 734 persons was performed in a working age population. Only healthy eyes were included. A comprehensive ophthalmological examination including refraction, noncontact tonometry, and imaging of the anterior segment by SD-OCT was performed. In parallel, a broad range of systemic cardiovascular parameters were measured. Associations were analyzed using a generalized estimating equations' model. Results. CCT measurements showed a significant association with corneal curvature and intraocular pressure: a thinner CCT was associated with a flatter cornea and with lower intraocular pressure (p < 0.001). Age was positively associated with CCT (p < 0.001); all other cardiovascular parameters were not associated. Conclusion. A thinner cornea is associated with a flatter surface and with lower intraocular pressure readings, while there are no independent associations with refraction and systemic cardiovascular parameters. Our findings highlight the value of SD-OCT CCT measurements as a standard tool in anterior segment analysis. PMID:27340561
The Atlas of Vesta Spectral Parameters derived from the mapping spectrometer VIR onboard NASA/Dawn
NASA Astrophysics Data System (ADS)
Frigeri, A.; De Sanctis, M.; Ammannito, E.; Tosi, F.; Capria, M.; Capaccioni, F.; Zambon, F.; Palomba, E.; Magni, G.; Jaumann, R.; Raymond, C. A.; Russell, C. T.
2013-12-01
From 2011 to 2012 the Visible and Infrared Mapping Spectrometer (VIR) onboard NASA/Dawn spacecraft has mapped the surface of Vesta from three different orbital heights, acquiring infrared and visible spectra from 0.2 to 5 microns, sampled in 864 channels with a spatial resolution up to about 150 m/pixel. From the large amount of spectra retrieved we have derived spectral parameters which can be combined to identify specific physical and compositional states. To start with, we have computed the band center and depth for band I and band II of pyroxenes. Pyroxene's band center I and II are commonly associated with a compositional variation. For example, orthopyroxene bands shift towards longer wavelengths with increasing amounts of iron, while clinopyroxene bands shift towards longer wavelengths with increasing calcium content. Band depths are related to scattering effects, associated to the abundance and the grain size of the absorber. Mapping these parameters on the surface allow to detect terrain units compositions and physical-state in their stratigraphic context. We have produced an atlas of digital maps, projected following the 15-quadrangle scheme commonly adopted for small sized planetary bodies. The digital maps have geospatial metadata and are available in GIS and other scientific programming language formats. A special imagery product has been produced, where the geomorphologic context from the Framing Camera, and the IAU nomenclature have been added to the mineralogic maps. This way we have both quantitative digital maps and print-ready maps. Digital maps are useful in statistical and geo-processing studies, while print-ready maps represent an easy to be consulted high-level data products. As with the atlas we are combining data acquired at very different observing geometries and in different phases of the mission, filtering has been necessary and an iterative process to project data produces results that are incrementally more consistent as we detect and
NASA Astrophysics Data System (ADS)
Manne, Jagadeeshwari; Webster, Christopher R.
2016-03-01
Molecular line parameters of line strengths, self- and foreign-broadening by nitrogen, carbon dioxide and helium gas have been experimentally determined for infrared ro-vibrational spectral lines of water and carbon dioxide at 2.78 μm targeted by the Tunable Laser Spectrometer (TLS) in the Sample Analysis at Mars (SAM) instrument suite on the Mars Science Laboratory (MSL) Curiosity rover. Good agreement is found by comparison with the line parameters reported in the HITRAN-2012 database.
Estimation of site-dependent spectral decay parameter from seismic array data
NASA Astrophysics Data System (ADS)
Park, Seon Jeong; Lee, Jung Mo; Baag, Chang-Eob; Choi, Hoseon; Noh, Myunghyun
2016-04-01
The kappa (κ), attenuation of acceleration amplitude at high frequencies, is one of the most important parameters in ground motion evaluation and seismic hazard analysis at sites. κ simply indicates the high frequency decay of the acceleration spectrum in log-linear space. The decay trend can be considered as linear for frequencies higher than a specific frequency, fe which is starting point of the linear regression at the acceleration spectrum. The κ has been investigated using the data from seismic arrays in the south-eastern part of Korea in which nuclear facilities such as power plant and radiological waste depository are located. The seismic array consists of 20 seismic stations and it was operated from October in 2010 through March in 2013. A classical method by Anderson and Hough (1984) and a standard procedure recently suggested by Ktenidou et al. (2013) were applied for computation of κ. There have been just a few studies on spectral attenuation characteristics for Korean Peninsula so far and even those studies utilized small amount of earthquake events whose frequency range was lower than 25 Hz. In this study, the available frequency range is up to 60 Hz based on the sampling rate of 200 and instrument response. This allows us to use a large range of frequencies for κ computations. It is outstanding advantage that we couldn't obtain from earlier κ studies in Korea. In addition, we investigate the regional κ characteristics through calculating the κ using data of 20 seismic stations which are highly extensive seismic array. It allows us to find the more specific attenuation characteristics of high frequencies in study area. Distance and magnitude dependence of κ has also been investigated. Before calculating the κ, the corner frequency (f_c) has been checked so that the fe can lie to the right of fc to exclude source effects in the computation. Manually picked fe is generally in the range of 10 to 25 Hz. The resulting κR is 9.2e-06 and κ0 is 0
NASA Astrophysics Data System (ADS)
Toki, Hiroshi; Abe, Masayuki
2016-03-01
Electromagnetic noise was studied theoretically by developing a multiconductor transmission-line (MTL) theory derived from Maxwell’s equations without any approximations. The MTL theory naturally contains the antenna process, and for the case of three lines it is written in terms of normal, common, and antenna modes. Here we develop a theoretical method to solve the MTL equations by introducing boundary conditions consisting of a lumped-parameter circuit in order to describe the performance of any electric circuit for good performance without noise. The finite-difference time-domain (FDTD) method is a powerful algorithm to solve time-dependent coupled differential equations for a combined distributed- and lumped-parameter circuit.
NASA Astrophysics Data System (ADS)
Schrader, T.; Kuhlmann, K.; Dickhoff, R.; Dittmer, J.; Hiebel, M.
2011-07-01
Radio-frequency (RF) scattering parameters (S-parameters) play an important role to characterise RF signal transmission and reflection of active and passive devices such as transmission lines, components, and small-signal amplifiers. Vector network analysers (VNAs) are employed as instrumentation for such measurements. During the last years, the upper frequency limit of this instrumentation has been extended up to several hundreds of GHz for waveguide measurements. Calibration and verification procedures are obligatory prior to the VNA measurement to achieve accurate results and/or to obtain traceability to the International System of Units (SI). Usually, verification is performed by measuring well-matched devices with known S-parameters such as attenuators or short precision waveguide sections (shims). In waveguides, especially above 110 GHz, such devices may not exist and/or are not traceably calibrated. In some cases, e.g. filter networks, the devices under test (DUT) are partly highly reflective. This paper describes the dependency of the S-parameters a) on the calibration procedure, b) on the applied torque to the flange screws during the mating process of the single waveguide elements. It describes further c) how highly-reflective devices (HRD) can be used to verify a calibrated VNA, and d) how a measured attenuation at several hundreds of GHz can be substituted by a well-known coaxial attenuation at 279 MHz, the intermediate frequency (IF) of the VNA, to verify the linearity. This work is a contribution towards traceability and to obtain knowledge about the measurement uncertainty of VNA instrumentation in the millimetre-wave range.
Measurement of atomic Stark parameters of many Mn I and Fe I spectral lines using GMAW process
NASA Astrophysics Data System (ADS)
Zielinska, S.; Pellerin, S.; Dzierzega, K.; Valensi, F.; Musiol, K.; Briand, F.
2010-11-01
The particular character of the welding arc working in pure argon, whose emission spectrum consists of many spectral lines strongly broadened by the Stark effect, has allowed measurement, sometimes for the first time, of the Stark parameters of 15 Mn I and 10 Fe I atomic spectral lines, and determination of the dependence on temperature of normalized Stark broadening in Ne = 1023 m-3 of the 542.4 nm atomic iron line. These results show that special properties of the MIG plasma may be useful in this domain because composition of the wire-electrode may be easily adapted to the needs of an experiment.
NASA Astrophysics Data System (ADS)
Bajaj, Annu; Jain, Sushma
2016-05-01
The present investigation is concerened with the studies on electronic spectral parameters viz. Oscillator strength (P), Judd-Ofelt Tλ (λ=2,4,6), Slater-Condon(FK),Lande(ζ4F),Nephelauxetic ratio(β), Bonding parameter (b1/2) and Percent covalency parameter (δ%) for Nd(III) ion complexes with the ligands having Nitrogen,Oxygen Sulphur donor sites.The variation in the values of oscillator strength explicitly shows the relative sensitivities of the 4f-4f transition as well as the specific correlation between ligand structures and nature of Nd(III) ligand interaction.
NASA Astrophysics Data System (ADS)
Amirkhizi, Alireza V.; Nemat-Nasser, Sia
2008-02-01
Through the use of conductive straight wires or coils the electromagnetic properties of a composite material can be modified. The asymmetric geometry of the coils creates an overall chiral response. The polarization vectors rotate as an electromagnetic wave travels through such a medium. To calculate the chirality of a medium prior to its manufacturing, we developed a method to extract all four electromagnetic material parameter tensors for a general uniaxial bianisotropic composite based on the numerical simulation of the electromagnetic fields. Our method uses appropriate line and surface field averages in a single unit cell of the periodic structure of the composite material. These overall field quantities have physical meaning only when the microscopic variation of the electromagnetic fields in the scale of the unit cell is not important, that is when the wavelength of interest is significantly larger than the maximum linear dimension of the unit cell. The overall constitutive relations of the periodic structure can then be obtained from the relations among the average quantities.
NASA Astrophysics Data System (ADS)
Wang, K.; Liu, F. C.; Xue, P.; Wang, D.; Xiao, B. L.; Ma, Z. Y.
2016-01-01
Fifteen Al-Mg-Sc samples with subgrain/grain sizes in the range of 1.8 to 4.9 μm were prepared through the processing methods of friction stir processing (FSP), equal-channel-angular pressing (ECAP), rolling, annealing, and combinations of the above. The percentages of high-angle grain boundaries (HAGBs) of these fine-grained alloys were distributed from 39 to 97 pct. The samples processed through FSP had a higher percentage of HAGBs compared to other samples. Superplasticity was achieved in all fifteen samples, but the FSP samples exhibited better superplasticity than other samples because their fine equiaxed grains, which were mostly surrounded by HAGBs, were conducive to the occurrence of grain boundary sliding (GBS) during superplastic deformation. The dominant deformation mechanism was the same for all fifteen samples, i.e., GBS controlled by grain boundary diffusion. However, the subgrains were the GBS units for the rolled or ECAP samples, which contained high percentages of unrecrystallized grains, whereas the fine grains were the GBS units for the FSP samples. Superplastic data analysis revealed that the dimensionless A in the classical constitutive equation for superplasticity of fine-grained Al alloys was not a constant, but increased with an increase in the percentage of HAGBs, demonstrating that the enhanced superplastic deformation kinetics can be ascribed to the high percentage of HAGBs. A modified superplastic constitutive equation with the percentage of HAGBs as a new microstructural parameter was established.
NASA Astrophysics Data System (ADS)
Wang, Chun; Liu, Xiaowei; Huang, Yang; Zuo, Fang; Yuan, Haibo; Ren, Juanjuan; Chen, Bingqiu; Xiang, Maosheng; Zhang, Huawei; Luo, Ali; Shi, Jianrong
2015-08-01
We present a new medium resolution (full width at half-maximum FWHM ~ 2.4 Å) spectral library containing 1903 stellar spectra with a wavelength coverage of 3800-9000 Å based on MILES spectral library which contains 985 blue arm spectra with wavelength coverage of 3500-7500 Å at a spectral resolution of 2.5 Å (FWHM). The spectra are observed with Chinese Xinglong 2.16 meter telescope of blue arm spectra (with wavelength coverage 3800-5180 Å ) and Gaomeigu 2.4 meter telescope of red arm spectra (with wavelength coverage 5150-9000 Å ), respectively. This new library aims to improve the stellar atmospheric parameters determination accuracy of LAMOST Stellar Parameter Pipeline at Peking University (LSP3) and minimize the limitation of LSP3 . It also could be used in the spectral synthesis of stellar populations of galaxies and many other astronomical fields. Now 560 blue arm and 496 red arm spectra have been observed and reduced. The accuracy of wavelength-calibration and flux-calibration are better than ~ 0.3 Å and ~ 5 per cent, respectively. The mean signal to noise ratios of all spectra are almost larger than 100 per Å.
The physical parameters of the low-mass multiple system LHS1070 from Spectral synthesis analysis
NASA Astrophysics Data System (ADS)
Rajpurohit, A. S.; Reylé, C.; Schultheis, M.; Leinert, C.; Allard, F.
2011-12-01
LHS1070 is a nearby multiple systems of low mass stars. It is an important source of information for probing the low mass end of the main sequence, down to the hydrogen-burning limit. The primary of the system consist of a mid-M dwarf and two components are late-M to L dwarf, at the star-brown dwarf transition. It makes it even more valuable to understand the formation of dust in cool stellar atmospheres.This work aims to determine the fundamental parameters of LHS1070 and to test recent model atmospheres.We compared the well calibrated data in the optical and infra-red with synthetic spectra computed from recent cool stars atmosphere models. We derived the physical parameters T_{eff}, radius and log g for three components of LHS1070. The models which include the formation and settle of dust are able to reproduce and describe the main features of the visible to IR spectra of the components.
Rapaport, Tal; Hochberg, Uri; Rachmilevitch, Shimon; Karnieli, Arnon
2014-01-01
Leaves of various ages and positions in a plant's canopy can present distinct physiological, morphological and anatomical characteristics, leading to complexities in selecting a single leaf for spectral representation of an entire plant. A fortiori, as growth rates between canopies differ, spectral-based comparisons across multiple plants – often based on leaves' position but not age – becomes an even more challenging mission. This study explores the effect of differential growth rates on the reflectance variability between leaves of different canopies, and its implication on physiological predictions made by widely-used spectral indices. Two distinct irrigation treatments were applied for one month, in order to trigger the formation of different growth rates between two groups of grapevines. Throughout the experiment, the plants were physiologically and morphologically monitored, while leaves from every part of their canopies were spectrally and histologically sampled. As the control vines were constantly developing new leaves, the water deficit plants were experiencing growth inhibition, resulting in leaves of different age at similar nodal position across the treatments. This modification of the age-position correlation was characterized by a near infrared reflectance difference between younger and older leaves, which was found to be exponentially correlated (R2 = 0.98) to the age-dependent area of intercellular air spaces within the spongy parenchyma. Overall, the foliage of the control plant became more spectrally variable, creating complications for intra- and inter-treatment leaf-based comparisons. Of the derived indices, the Structure-Insensitive Pigment Index (SIPI) was found indifferent to the age-position effect, allowing the treatments to be compared at any nodal position, while a Normalized Difference Vegetation Index (NDVI)-based stomatal conductance prediction was substantially affected by differential growth rates. As various biotic and
Chen Shihua; Liu Yi; Mysyrowicz, Andre
2010-06-15
The stability of a one-parameter family of dissipative solitons seen in the cubic-quintic complex Ginzburg-Landau equation is studied. It is found that an unusually strong stability occurs for solitons controlled by the spectral filtering and nonlinearity saturation simultaneously, consistently with the linear stability analysis and confirmed by large-perturbation numerical simulations. Two universal types of bifurcations in the spectrum structure are demonstrated.
Comim, Fabio V.; Gutierrez, Karina; Bridi, Alessandra; Bochi, Guilherme; Chemeris, Raisa; Rigo, Melânia L.; Dau, Andressa Minussi P.; Cezar, Alfredo S.; Moresco, Rafael Noal; Gonçalves, Paulo Bayard Dias
2016-01-01
Adiponectin is the most abundantly produced human adipokine with anti-inflammatory, anti-oxidative, and insulin-sensitizing properties. Evidence from in vitro studies has indicated that adiponectin has a potential role in reproduction because it reduces the production of androstenedione in bovine theca cells in vitro. However, this effect on androgen production has not yet been observed in vivo. The current study evaluated the effect of adiponectin on androstenedione secretion and oxidative stress parameters in a rodent model. Seven-week-old female Balb/c mice (n = 33), previously treated with equine gonadotropin chorionic, were assigned to one of four different treatments: Group 1, control (phosphate-buffered saline); Group 2, adiponectin 0.1 μg/mL; Group 3, adiponectin 1.0 μg/mL; Group 4, adiponectin 5.0 μg/mL. After 24 h, all animals were euthanized and androstenedione levels were measured in the serum while oxidative stress markers were quantified in whole ovary tissue. Female mice treated with adiponectin exhibited a significant reduction (about 60%) in serum androstenedione levels in comparison to controls. Androstenedione levels decreased from 0.78 ± 0.4 ng/mL (mean ± SD) in controls to 0.28 ± 0.06 ng/mL after adiponectin (5 μg/mL) treatment (P = 0.01). This change in androgen secretion after 24 hours of treatment was associated with a significant reduction in the expression of CYP11A1 and STAR (but not CYP17A1). In addition, ovarian AOPP product levels, a direct product of protein oxidation, decreased significantly in adiponectin-treated mice (5 μg/mL); AOPP (mean ± SD) decreased to 4.3 ± 2.1 μmol/L in comparison with that of the controls (11.5 ± 1.7 μmol/L; P = 0.0003). Our results demonstrated for the first time that acute treatment with adiponectin reduced the levels of a direct oxidative stress marker in the ovary as well as decreased androstenedione serum levels in vivo after 24 h. PMID:27158926
NASA Astrophysics Data System (ADS)
Bonte, M. H. A.; de Boer, A.; Liebregts, R.
2007-04-01
This paper provides a new formula to take into account phase differences in the determination of an equivalent von Mises stress power spectral density (PSD) from multiple random inputs. The obtained von Mises PSD can subsequently be used for fatigue analysis. The formula was derived for use in the commercial vehicle business and was implemented in combination with Finite Element software to predict and analyse fatigue failure in the frequency domain.
Spectrum of one BVP with discontinuities and spectral parameter in the boundary conditions
NASA Astrophysics Data System (ADS)
Aydemir, K.; Mukhtarov, O. Sh.; Olǧar, H.
2016-04-01
The aim this of paper is to investigate the spectral problem for the equation -(pu')'(x) + q(x)u(x) = λu(x), under eigen-dependent boundary conditions and supplementary transmission conditions at finite number interior points. By modifying some techniques of classical Sturm-Liouville theory and suggesting own approaches we esthabilish some properties of the eigenvalues and eigenfunction.
NASA Astrophysics Data System (ADS)
Masden, G. W.
An algorithm for the determination of photovoltaic cell parameters and absolute spectral response from terminal V-I measurements is presented. Input consists of V-I curve data measured with the cell operating under full-test illumination, the spectral distribution of the test illumination, the short circuit current response to superimposed quasi-monochromatic illumination and the spectral distribution of the quasi-monochromatic illumination. The algorithm yields internal spectral response and approximate values for cell model parameters such as minority carrier lifetimes, doping densities, junction depth, recombination velocities, and/or others provided the sensitivity of the cell response to changes in the parameter allows a satisfactory resolution of the parameter. Effects of measurement errors on the computed spectral response and parameters are presented.
Spectral Parameters of HRV In Yoga Practitioners, Athletes And Sedentary Males.
Peter, Rosemary; Sood, Sushma; Dhawan, Ashwani
2015-01-01
Physical inactivity is an important risk factor for cardiovascular mortality and morbidity. Exercise is considered an acceptable method for improving and maintaining physical and emotional health. Although yoga is historically a spiritual discipline, a growing body of evidence supports the belief that yoga benefits physical and mental health. The objective of this study was to evaluate heart rate variability which reflects autonomic control of heart among yoga practitioners, athletes and individuals with sedentary lifestyle. The study was carried out in the departments of physiology at MAMC Agroha, Hisar and Pt. BD Sharma PGIMS Rohtak, Haryana. The study group comprised of 1200 healthy male volunteers of 16 to 55 years of age. The study group was divided into four age groups: Group A of age 16 to 25 years; Group B of age 26 to 35 years; Group C of age 36 to 45 years and Group D of age 46 to 55 years. All age groups were further divided into three categories i.e athlete (runner), yoga (yoga practitioners) and sedentary in which individuals with sedentary life style were included. The basal recording of ECG in lead II was done for 5 minutes. The Polyrite-D ECG data was used for analysis of heart rate variability by frequency domain method. Two spectral components were recorded namely high frequency (HF) component (0.15-0.4 Hz), an indicator of vagal efferent activity and low frequency (LF) component (0.04-.15 Hz), replicator of composite sympatho-vagal interplay. HF component in normalized unit was found significantly high in age group B and C in yoga practitioners and athletes as compared to sedentary individuals and in age group D significantly high in yoga practitioners as compared to athletes and sedentary individuals. Significantly decreased LF/HF ratio was found in age group B and C in yoga and athlete subjects as compared to sedentary individuals and in age group D in yoga practitioners as compared to athletes and sedentary individuals. This indicates that
Kunerth, Dennis C.; Svoboda, John M.; Johnson, James T.
2007-03-06
A method of measuring a parameter of a landfill including a cap, without passing wires through the cap, includes burying a sensor apparatus in the landfill prior to closing the landfill with the cap; providing a reader capable of communicating with the sensor apparatus via radio frequency (RF); placing an antenna above the barrier, spaced apart from the sensor apparatus; coupling the antenna to the reader either before or after placing the antenna above the barrier; providing power to the sensor apparatus, via the antenna, by generating a field using the reader; accumulating and storing power in the sensor apparatus; sensing a parameter of the landfill using the sensor apparatus while using power; and transmitting the sensed parameter to the reader via a wireless response signal. A system for measuring a parameter of a landfill is also provided.
NASA Astrophysics Data System (ADS)
Filippazzo, Joe; Rice, Emily L.; Faherty, Jacqueline K.; Cruz, Kelle L.; Godfrey, Paige A.; BDNYC
2016-01-01
The physical and atmospheric properties of ultracool dwarfs are deeply entangled due to the degenerate effects of mass, age, metallicity, clouds and dust, activity, rotation, and possibly even formation mechanism on observed spectra. Accurate determination of fundamental parameters for a wide diversity of objects at the low end of the IMF is thus crucial to testing stellar and planetary formation theories. To determine these quantities, we constructed and flux calibrated nearly-complete spectral energy distributions (SEDs) for 221 M, L, T, and Y dwarfs using published parallaxes and 0.3-40 μm spectra and photometry. From these homogeneous SEDs, we calculated bolometric luminosity (Lbol), effective temperature (Teff), mass, surface gravity, radius, spectral indexes, synthetic photometry, and bolometric corrections (BCs) for each object. We used these results to derive Lbol, Teff, and BC polynomial relations across the entire very-low-mass star/brown dwarf/planetary mass regime. We use a subsample of objects with age constraints based on nearby young moving group membership, companionship with a young star, or spectral signatures of low surface gravity to define new age-sensitive diagnostics and characterize the reddening of young substellar atmospheres as a redistribution of flux from the near-infrared into the mid-infrared. Consequently we find the SED flux pivots at Ks band, making BCKs as a function of spectral type a tight and age independent relationship. We find that young L dwarfs are systematically 300 K cooler than field age objects of the same spectral type and up to 600 K cooler than field age objects of the same absolute H magnitude. Finally, we present preliminary comparisons of these empirical results to best fit parameters from four different model atmosphere grids via Markov-Chain Monte Carlo analysis in order to create prescriptions for the reliable and efficient characterization of new ultracool dwarfs.
NASA Astrophysics Data System (ADS)
Benner, D. Chris; Devi, V. Malathy; Sung, Keeyoon; Brown, Linda R.; Miller, Charles E.; Payne, Vivienne H.; Drouin, Brian J.; Yu, Shanshan; Crawford, Timothy J.; Mantz, Arlan W.; Smith, Mary Ann H.; Gamache, Robert R.
2016-08-01
This study reports the results from analyzing a number of high resolution, high signal-to-noise ratio (S/N) spectra in the 2.06-μm spectral region for pure CO2 and mixtures of CO2 in dry air. A multispectrum nonlinear least squares curve fitting technique has been used to retrieve the various spectral line parameters. The dataset includes 27 spectra: ten pure CO2, two 99% 13C-enriched CO2 and fifteen spectra of mixtures of 12C-enriched CO2 in dry air. The spectra were recorded at various gas sample temperatures between 170 and 297 K. The absorption path lengths range from 0.347 to 49 m. The sample pressures for the pure CO2 spectra varied from 1.1 to 594 Torr; for the two 13CO2 spectra the pressures were ∼10 and 146 Torr. For the air-broadened spectra, the pressures of the gas mixtures varied between 200 and 711 Torr with CO2 volume mixing ratios ranging from 0.014% to 0.203%. The multispectrum fitting technique was applied to fit simultaneously all these spectra to retrieve consistent set of line positions, intensities, and line shape parameters including their temperature dependences; for this, the Voigt line shape was modified to include line mixing (via the relaxation matrix formalism) and quadratic speed dependence. The new results are compared to select published values, including recent ab initio calculations. These results are required to retrieve the column averaged dry air mole fraction (XCO2) from space-based observations, such as the Orbiting Carbon Observatory-2 (OCO-2) satellite mission that NASA launched in July 2014.
Zhou, Minghao; Meng, Fangang
2016-04-15
The integration of pre-coagulation with ultrafiltration (UF) is expected to not only reduce membrane fouling but also improve natural organic matter (NOM) removal. However, it is difficult to determine the proper coagulant dosage for different water qualities. The objective of this study was to probe the potential of UV-vis spectroscopic analysis to reveal the coagulant-induced changes in the fouling potentials of dissolved organic matter (DOM) and to determine the optimal coagulant dosage. The Zeta potentials (ZPs) and average particle size of the four DOM solutions (Aldrich humic acid (AHA), AHA-sodium alginate (SA), AHA-bovine serum albumin (BSA) and AHA-dextran (DEX)) coagulated with aluminum chloride (AlCl3) were measured. Results showed that increasing the aluminum coagulant dosage induced the aggregation of DOM. Meanwhile, the addition of aluminum coagulant resulted in an increase in DSlope(325-375) (the slope of the log-transformed absorbance spectra from 325 to 375 nm) and a decrease in S(275-295) (the slope of the log-transformed absorption coefficient from 275 to 295 nm) and SR (the ratio of Slope(275-295) and Slope(350-400)). The variations of these spectral parameters (i.e., DSlope(325-375), S(275-295) and SR) correlated well with the aluminum-caused changes in ZPs and average particle size. This implies that spectral parameters have the potential to indicate DOM aggregation. In addition, good correlations of spectral parameters and membrane fouling behaviors (i.e., unified membrane fouling index (UMFI)) suggest that the changes in DSlope(325-375), S(275-295) and SR were indicative of the aluminum-caused alterations of fouling potentials of all DOM solutions. Interestingly, the optimal dosage of aluminum (40 μM for AHA, AHA-BSA, and AHA-DEX) was obtained based on the relation between spectral parameters and fouling behaviors. Overall, the spectroscopic analysis, particularly for the utilization of spectral parameters, provided a convenient approach
Correlation between spectral state and quasi-periodic oscillation parameters in GX 5-1
NASA Technical Reports Server (NTRS)
Van Der Klis, M.; Jansen, F.; Van Paradijs, J.; Lewin, W. H. G.; Sztajno, M.
1987-01-01
In a series of seven Exosat observations, the bimodal spectral behavior and the quasi-periodic oscillation (QPO)/red noise properties of GX 5-1 show a strict correlation. In one of the two spectral states (characterized by a 'horizontal branch' in the hardness-intensity diagram), strong 20-40 Hz QPO and red noise below about 60 Hz were always present. In the other ('normal branch'), no QPO between 6 and 60 Hz or red noise above 1 Hz were detected, but there was an indication for weak QPO near 5 Hz. In both states 'very low frequency noise' (VLFN) is detected below 0.1 Hz which has a power-law shape and and which extends down to the lowest observed frequencies (0.0001 Hz). The VLFN is probably not directly related to the QPO. The results are compared to those on Sco X-1 and Cyg X-2 and it is concluded that, although all three sources show bimodal spectral and QPO/red noise behavior, there is a qualitative difference between GX 5-1 and Cyg X-2 on one hand and Sco X-1 on the other.
Effects of Spectral and Temporal Variations in Gamma Ray Burst Parameters
NASA Astrophysics Data System (ADS)
Ejzak, L. M.; Melott, A. L.; Thomas, B. C.; Medvedev, M. V.
2005-12-01
It has previously been shown that a typical gamma ray burst could have significant effects on the Earth, including such considerations as ozone depletion and production of odd nitrogen compounds. These effects in turn contribute to processes such as DNA damage in organisms, increasing opacity of the atmosphere, and nitric acid rain. Our interest lies in the role that these processes may play in mass extinction events, in particular the Ordovician mass extinction 443 Mya. Here we investigate variations in certain burst parameters and the resulting variation in the severity of effect that the burst radiation has on the Earth's atmosphere. We extend the range of photon energies used in the model beyond the range used in previous studies, and model bursts with a number of different peak energies. We also alter the temporal profile of the radiation during the burst itself. This research is conducted with support from NASA's Astrobiology: Exobiology and Evolutionary Biology Program and in collaboration with NASA's Goddard Space Flight Center, and with supercomputer support from NCSA.
NASA Astrophysics Data System (ADS)
Feleppa, Ernest J.; Ketterling, Jeffrey A.; Dasgupta, Shreedevi; Kalisz, Andrew; Ramachandran, Sarayu; Porter, Christopher R.
2005-04-01
This study seeks to develop more-sensitive and -specific ultrasonic methods of imaging cancerous prostate tissue and thereby to improve means of guiding biopsies and planning, targeting, and monitoring treatment. Ultrasonic radio-frequency, echo-signal data, and clinical variables, e.g., PSA, voiding function, etc., during biopsy examinations were acquired. Spectra of the radio-frequency signals were computed in each biopsied region, and used to train neural networks; biopsy results served as the gold standard. A lookup table gave scores for cancer likelihood on a pixel-by-pixel basis from locally computed spectral-parameter and global clinical-parameter values. ROC curves used leave-one-patient- and leave-one-biopsy-out approaches to minimize classification bias. Resulting ROC-curve areas were 0.80+/-0.03 for neural-networks versus 0.66+/-0.03 for conventional classification. TTIs generated from data acquired pre-surgically showed tumors that were unrecognized in conventional images and during surgery. 3-D renderings of prostatectomy histology and TTIs showed encouraging correlations, which shows promise for improving the detection and management of prostate cancer, e.g., for biopsy guidance, planning dose-escalation and tissue-sparing options for radiation or cryotherapy, and assessing the effects of treatment. Combining MRS parameters with US spectral parameters appears capable of further improving prostate-cancer imaging. [Work supported by NIH.
Estimations of Mo X-pinch plasma parameters on QiangGuang-1 facility by L-shell spectral analyses
Wu, Jian; Qiu, Aici; Li, Mo; Wang, Liangping; Wu, Gang; Ning, Guo; Qiu, Mengtong; Li, Xingwen
2013-08-15
Plasma parameters of molybdenum (Mo) X-pinches on the 1-MA QiangGuang-1 facility were estimated by L-shell spectral analysis. X-ray radiation from X-pinches had a pulsed width of 1 ns, and its spectra in 2–3 keV were measured with a time-integrated X-ray spectrometer. Relative intensities of spectral features were derived by correcting for the spectral sensitivity of the spectrometer. With an open source, atomic code FAC (flexible atomic code), ion structures, and various atomic radiative-collisional rates for O-, F-, Ne-, Na-, Mg-, and Al-like ionization stages were calculated, and synthetic spectra were constructed at given plasma parameters. By fitting the measured spectra with the modeled, Mo X-pinch plasmas on the QiangGuang-1 facility had an electron density of about 10{sup 21} cm{sup −3} and the electron temperature of about 1.2 keV.
Xu, Mingsheng; Zhang, Haoxiang; Zhou, Quanbin; Wang, Hong
2016-06-01
Red-green-blue white light-emitting diodes (RGB-WLEDs) have great potential as commercial solid-state lighting devices, as well as visible light communication because of their high color-rendering index (CRI) and high response frequency. The quality of light of an RGB-WLED strongly depends on its spectral parameters. In this study, we fabricated RGB-WLEDs with red, blue, and green LEDs and measured the spectral power distribution (SPD). The experimental SPD is consistent with the calculated spectrum. We also measured the SPDs of LEDs with different peak wavelengths and extracted the spectral parameters, which were then used for modeling. We studied the effect of the wavelength and the full width at half-maximum (FWHM) on both the color rendering index and the luminous efficiency (LE) of the RGB-WLED using simulations. We find that the LE improves as the wavelength of the blue LED increases and the wavelength of the red LED decreases. When the wavelength of the green LED increases, the LE increases first, but later decreases. The CRI of the RGB-WLED increases with the wavelengths of the red, blue, and green LEDs first, but then decreases. The optimal wavelengths and FWHMs for maximum color-rendering and LE of the blue, green, and red LEDs are 466, 536, 606 nm; and 26.0, 34.0, and 19.5 nm, respectively. PMID:27411203
NASA Astrophysics Data System (ADS)
Stiele, H.; Belloni, T. M.; Kalemci, E.; Motta, S.
2013-03-01
We present a study of correlations between spectral and timing parameters for a sample of black hole X-ray binary candidates. Data are taken from GX 339-4, H1743-322 and XTE J1650-500, as the Rossi X-ray Timing Explorer observed complete outbursts of these sources. In our study we investigate outbursts that happened before the end of 2009 to make use of the high-energy coverage of the High Energy X-ray Timing Experiment detector and select observations that show a certain type of quasi-periodic oscillations (QPOs; type-C). The spectral parameters are derived using the empirical convolution model SIMPL to model the Comptonized component of the emission together with a disc blackbody for the emission of the accretion disc. Additional spectral features, namely a reflection component, a high-energy cut-off and excess emission at 6.4 keV, are taken into account. Our investigations confirm the known positive correlation between photon index and centroid frequency of the QPOs and reveal an anticorrelation between the fraction of up-scattered photons and the QPO frequency. We show that both correlations behave as expected in the `sombrero' geometry. Furthermore, we find that during outburst decay the correlation between photon index and QPO frequency follows a general track, independent of individual outbursts.
NASA Astrophysics Data System (ADS)
Krezhova, Dora D.; Kirova, Elisaveta B.; Yanev, Tony K.; Iliev, Ilko Ts.
2010-01-01
Measurements of physiology and hyperspectral leaf reflectance were used to detect salinity stress in nitrogen fixing soybean plants. Seedlings were inoculated with suspension of Bradyrhizobium japonicum strain 273. Salinity was performed at the stage of 2nd-4th trifoliate expanded leaves by adding of NaCl in the nutrient solution of Helrigel in concentrations 40 mM and 80 mM. A comparative analysis was performed between the changes in the biochemical parameters - stress markers (phenols, proline, malondialdehyde, thiol groups), chlorophyll a and b, hydrogen peroxide, and leaf spectral reflectance in the spectral range 450-850 nm. The spectral measurements were carried out by an USB2000 spectrometer. The reflectance data of the control and treated plants in the red, green, red-edge and the near infrared ranges of the spectrum were subjected to statistical analysis. Statistically significant differences were found through the Student's t-criterion at the two NaCl concentrations in all of the ranges examined with the exception of the near infrared range at 40 mM NaCl concentration. Similar results were obtained through linear discriminant analysis. The tents of the phenols, malondialdehyde and chlorophyll a and b were found to decrease at both salinity treatments. In the spectral data this effect is manifested by decrease of the reflectance values in the green and red ranges. The contents of proline, hydrogen peroxide and thiol groups rose with the NaCl concentration increase. At 80 mM NaCl concentration the values of these markers showed a considerable increase giving evidence that the soybean plants were stressed in comparison with the control. This finding is in agreement with the results from the spectral reflectance analysis.
Estimation of Tissue Optical Parameters with Hyperspectral Imaging and Spectral Unmixing
Lu, Guolan; Qin, Xulei; Wang, Dongsheng; Chen, Zhuo Georgia; Fei, Baowei
2015-01-01
Early detection of oral cancer and its curable precursors can improve patient survival and quality of life. Hyperspectral imaging (HSI) holds the potential for noninvasive early detection of oral cancer. The quantification of tissue chromophores by spectral unmixing of hyperspectral images could provide insights for evaluating cancer progression. In this study, non-negative matrix factorization has been applied for decomposing hyperspectral images into physiologically meaningful chromophore concentration maps. The approach has been validated by computer-simulated hyperspectral images and in vivo tumor hyperspectral images from a head and neck cancer animal model. PMID:26855467
Estimation of tissue optical parameters with hyperspectral imaging and spectral unmixing
NASA Astrophysics Data System (ADS)
Lu, Guolan; Qin, Xulei; Wang, Dongsheng; Chen, Zhuo G.; Fei, Baowei
2015-03-01
Early detection of oral cancer and its curable precursors can improve patient survival and quality of life. Hyperspectral imaging (HSI) holds the potential for noninvasive early detection of oral cancer. The quantification of tissue chromophores by spectral unmixing of hyperspectral images could provide insights for evaluating cancer progression. In this study, non-negative matrix factorization has been applied for decomposing hyperspectral images into physiologically meaningful chromophore concentration maps. The approach has been validated by computer-simulated hyperspectral images and in vivo tumor hyperspectral images from a head and neck cancer animal model.
Dzhebrailova, T D; Korobeĭnikova, I I; Rudneva, L P
2014-09-01
EEG spectral power was calculated in 24 students (18-21 years) with different levels of motivation and anxiety (tested by Spielberger) in two experimental conditions: during the common educational process and the examination stress. Before examination tests, in subjects with high motivation and anxiety level the relative delta activity power increased in right frontal (F4) brain areas. In students with medium motivation immediately before an examination the relative beta2-activity power increased in right frontal (F4) brain areas. It is suggested that delta oscillati- ons reflect activity of the defensive motivational system, whereas beta2 oscillations may be associated with the achievement motivation. PMID:25697016
NASA Astrophysics Data System (ADS)
Zygielbaum, A. I.; Arkebauer, T. J.; Walter-Shea, E.
2014-12-01
Previously, we reported that reflectance increased across the whole PAR spectrum when plants were subjected to water stress. This effect was shown to exist in maize grown under greenhouse conditions and under field conditions. Greenhouse experiments showed that, in addition to leaf water content, the effect was strongly correlated with incident light intensity. Further, through the use of an integrating sphere, we demonstrated that the change in reflectance was due to a change in absorption rather than in a change scattering or other optical path effect. Time lapse microscopy showed lightening between leaf veins analogous to effects measured by researchers observing cross sections of stressed C4 plants. To further refine our study, additional leaf level and canopy level studies were undertaken. Excised leaf sections were separately exposed to red and white light in the laboratory as the leaf dried. Increasing reflectance and transmittance were observed for the section exposed to white light, while little change was observed under red light. Each of these observations can be explained by chloroplast avoidance movement, a photoprotective response causing chloroplasts to aggregate along cell walls effectively hiding chlorophyll from observation. Chloroplast movement, for example, is driven by blue light; explaining the lack of observed change under red light. Estimation of biophysical parameters, such as chlorophyll content and greenness, are affected by the difference between the "apparent" chlorophyll content and the actual chlorophyll content of leaves and canopies. Up to 30% changes in the VARI remote sensing index have been observed morning to afternoon in field-grown maize. Ten percent changes in chlorophyll estimates have been observed in greenhouse maize. We will report on further research and on the extension of our work to include the impact of chloroplast avoidance on remote sensing of C3 plants, specifically soybean, at leaf and canopy levels.
NASA Astrophysics Data System (ADS)
Ghorbani, Ahmad; Camerlynck, Christian; Florsch, Nicolas
2009-02-01
An inversion code has been constructed using Matlab, to recover 1D parameters of the Cole-Cole model from spectral induced polarization data. In a spectral induced polarization survey, impedances are recorded at various frequencies. Both induced polarization and electromagnetic coupling effects occur simultaneously over the experimental frequency bandwidth, and these become progressively more dominant when the frequency increases. We used the CR1Dmod code published by Ingeman-Nielsen and Baumgartner [2006]. This code solves for electromagnetic responses, in the presence of complex resistivity effects in a 1D Earth. In this paper, a homotopy method has been designed by the authors to overcome the local convergence problem of normal iterative methods. In addition, in order to further condition the inverse problem, we incorporated standard Gauss-Newton (or quasi-Newton) methods. Graphical user interfaces enable straightforward entering of the data and the a priori model, as well as the cable configuration. Two synthetic examples are presented, showing that the spectral parameters can be recovered from multifrequency, complex resistivity data.
NASA Astrophysics Data System (ADS)
Zhu, Jianhua; Wan, Lei; Nie, Guosheng; Guo, Xiaowei
2003-12-01
In this paper, as far as we know, it is the first time that a novel acousto-optic pure rotational Raman lidar based on acousto-optic tunable filter (AOTF) is put forward for the application of atmospheric temperature measurements. AOTF is employed in the novel lidar system as narrow band-pass filter and high-speed single-channel wavelength scanner. This new acousto-optic filtering technique can solve the problems of conventional pure rotational Raman lidar, e.g., low temperature detection sensitivity, untunability of filtering parameters, and signal interference between different detection channels. This paper will focus on the PRRS physical model calculation and simulation optimization of system parameters such as the central wavelengths and the bandwidths of filtering operation, and the required sensitivity. The theoretical calculations and optimization of AOTF spectral filtering parameters are conducted to achieve high temperature dependence and sensitivity, high signal intensities, high temperature of filtered spectral passbands, and adequate blocking of elastic Mie and Rayleigh scattering signals. The simulation results can provide suitable proposal and theroetical evaluation before the integration of a practical Raman lidar system.
Spectral and energy parameters of multiband barrier-discharge KrBr excilamps
Avdeev, S M; Erofeev, M V; Skakun, V S; Sosnin, E A; Suslov, A I; Tarasenko, V F; Schitz, D V
2008-07-31
The spectral and energy characteristics of multiband barrier-discharge coaxial KrBr excilamps are studied experimentally at pressures from a few tens of Torr to 0.4 atm. It is shown that an increase in the Br{sub 2} concentration reduces the emission intensity of KrBr* molecules with respect to the emission intensity of Br{sub 2}* molecules and reduces the total emission power of the excilamp. This can be explained by the nonradiative decay of exciplex KrBr* molecules caused by their quenching by molecular bromine. The emission power and efficiency in the Kr:Br{sub 2} = 400:1 mixture at a pressure of {approx}230 Torr and a discharge gap of 8.5 mm were 4.8 W and 2.4%, respectively. (laser applications and other topics in quantum electronics)
NASA Technical Reports Server (NTRS)
Suit, W. T.
1986-01-01
Shuttle flight test data were used to determine values for the short-period parameters. The best identified, as judged by its estimated standard deviation, was the elevon effectiveness parameter C (sub m (sub sigma e squared)). However, the scatter about the preflight prediction of C (sub m (sub sigma e squared)) was large. Other investigators have suggested that adding nonlinear terms to the mathematical model used to identify C (sub m (sub sigma e)) could reduce the scatter. The results of this investigation show that C (sub m (sub sigma e squared)) is the only identifiable nonlinear parameter applicable and that the changes in C (sub m (sub sigma e)) values when C (sub m (sub sigma e squared)) is included are in the order of ten percent for the data estimated.
Tanikawa, Tomonori; Li, Wei; Kuchiki, Katsuyuki; Aoki, Teruo; Hori, Masahiro; Stamnes, Knut
2015-11-30
A new retrieval algorithm for estimation of snow grain size and impurity concentration from spectral radiation data is developed for remote sensing applications. A radiative transfer (RT) model for the coupled atmosphere-snow system is used as a forward model. This model simulates spectral radiant quantities for visible and near-infrared channels. The forward RT calculation is, however, the most time-consuming part of the forward-inverse modeling. Therefore, we replaced it with a neural network (NN) function for fast computation of radiances and Jacobians. The retrieval scheme is based on an optimal estimation method with a priori constraints. The NN function was also employed to obtain an accurate first guess in the retrieval scheme. Validation with simulation data shows that a combination of NN techniques and optimal estimation method can provide more accurate retrievals than by using only NN techniques. In addition, validation with in-situ measurements conducted by using ground-based spectral radiometer system shows that comparison between retrieved snow parameters with in-situ measurements is acceptable with satisfactory accuracy. The algorithm provides simultaneous, accurate and fast retrieval of the snow properties. The algorithm presented here is useful for airborne/satellite remote sensing. PMID:26698793
Mishra, Shubha; Limaye, S. N.
2015-07-31
It is said that the -4f shells behave as core and are least perturbed by changes around metal ion surrounding. However, there are evidences that-4f shells partially involved in direct moderator interaction. A systematic investigation on the plasmonic (electronic) spectral studies of some Rare Earths[RE(III).Mod] where, RE(III) = Pr(III),Nd(III) and Mod(moderator) = Y(III),La(III),Gd(III) and Lu(III), increased moderator concentration from 0.01 mol dm{sup −3} to 0.025 mol dm{sup −3} keeping the metal ion concentration at 0.01mol dm{sup −3} have been carried out. Variations in oscillator strengths (f), Judd-Ofelt parameters (T{sub λ}),inter-electronic repulsion Racah parameters (δE{sup k}),nephelauxetic ratio (β), radiative parameters (S{sub ED},A{sub T},β{sub R},T{sub R}). The values of oscillator strengths and Judd-Ofelt parameters have been discussed in the light of coordination number of RE(III) metal ions, denticity and basicity of the moderators. The [RE(III).Mod] bonding pattern has been studies in the light of the change in Racah parameters and nephelauxetic ratio.
NASA Astrophysics Data System (ADS)
Gnyba, M.; Wróbel, M. S.; Karpienko, K.; Milewska, D.; Jedrzejewska-Szczerska, M.
2015-07-01
In this article the simultaneous investigation of blood parameters by complementary optical methods, Raman spectroscopy and spectral-domain low-coherence interferometry, is presented. Thus, the mutual relationship between chemical and physical properties may be investigated, because low-coherence interferometry measures optical properties of the investigated object, while Raman spectroscopy gives information about its molecular composition. A series of in-vitro measurements were carried out to assess sufficient accuracy for monitoring of blood parameters. A vast number of blood samples with various hematological parameters, collected from different donors, were measured in order to achieve a statistical significance of results and validation of the methods. Preliminary results indicate the benefits in combination of presented complementary methods and form the basis for development of a multimodal system for rapid and accurate optical determination of selected parameters in whole human blood. Future development of optical systems and multivariate calibration models are planned to extend the number of detected blood parameters and provide a robust quantitative multi-component analysis.
On spectral properties of a Shrödinger operator with a negative parameter
NASA Astrophysics Data System (ADS)
Muratbekov, Mussakan; Muratbekov, Madi
2016-08-01
In this paper, the issues on the existence of the resolvent, the discreteness of spectrum, the estimates of the distribution function of singular values (s-values) are studied for a Schrödinger operator with a negative parameter under certain restrictions on coefficients.
NASA Astrophysics Data System (ADS)
Kashaev, R. S.; Gazizov, E. G.
2010-07-01
The influence of laser and non-coherent irradiation on the state of oil components has been studied at wavelengths of 630 and 1825 nm, respectively. New results reflecting changes in structural-dynamic parameters of the molecular motion as a function of exposure time have been obtained. The variations of NMR parameters during NIR irradiation of an oil sample prepared with the addition of paraffin (docosane) seem to be connected with "washing out" of these nanodimensional structures and can be explained theoretically in terms of the phenomenological description of the energy-level population behavior. The method of NMR relaxometry used in parallel with laser and non-coherent radiation in the NIR spectral region has been shown to enable one to readily determine oil components that are difficult to estimate by conventional techniques.
NASA Astrophysics Data System (ADS)
Chandran, Senthilkumar; Jagan, R.; Paulraj, Rajesh; Ramasamy, P.
2015-10-01
Metal-organic bis(hydrogenmaleate)-Co(II) tetrahydrate single crystals have been grown by slow evaporation solution growth technique at room temperature. The crystal structure and the unit cell parameters were analyzed from the X-ray diffraction studies. Single-crystal X-ray diffraction analyses reveal that the grown crystal belongs to triclinic system with the space group P-1. Functional groups in bis(hydrogenmaleate)-Co(II) tetrahydrate were identified by Fourier transform infrared spectral analysis. The peak observed at 663 cm-1 is assigned to the (Co-O) stretching vibrations. The optical transmission of the crystal was studied by UV-vis-NIR spectral analysis. The photoluminescence emission studies were carried out for the title compound in a wide wavelength range between 350 nm and 550 nm at 303 K. Mechanical strength was tested by Vickers microhardness test. The laser damage threshold value has been determined using Nd:YAG laser operating at 1064 nm. At various frequencies and temperatures the dielectric behavior of the material was investigated. Solid state parameters such as plasma energy, Penn gap, Fermi energy and electronic polarizability were evaluated. Photoconductivity measurements were carried out for the grown crystal in the presence of DC electric field at room temperature. Thermal stability and decomposition of the crystal were studied by TG-DTA. The weight loss of the title compound occurs in different steps.
Use of spectral imaging for documentation of skin parameters in face lift procedure
NASA Astrophysics Data System (ADS)
Ruvolo, Eduardo C., Jr.; Bargo, Paulo R.; Dietz, Tim; Scamuffa, Robin; Shoemaker, Kurt; DiBernardo, Barry; Kollias, Nikiforos
2010-02-01
In rhytidectomy the postoperative edema (swelling) and ecchymosis (bruising) can influence the cosmetic results. Evaluation of edema has typically been performed by visual inspection by a trained physician using a fourlevel or, more commonly, a two-level grading(1). Few instruments exist capable of quantitatively assessing edema and ecchymosis in skin. Here we demonstrate that edema and ecchymosis can be objectively quantitated in vivo by a multispectral clinical imaging system (MSCIS). After a feasibility study of induced stasis to the forearms of volunteers and a benchtop study of an edema model, five subjects undergoing rhytidectomy were recruited for a clinical study and multispectral images were taken approximately at days 0, 1, 3, 6, 8, 10, 15, 22 and 29 (according with the day of their visit). Apparent concentrations of oxy-hemoglobin, deoxy-hemoglobin (ecchymosis), melanin, scattering and water (edema) were calculated for each pixel of a spectral image stack. From the blue channel on cross-polarized images bilirubin was extracted. These chromophore maps are two-dimensional quantitative representations of the involved skin areas that demonstrated characteristics of the recovery process of the patient after the procedure. We conclude that multispectral imaging can be a valuable noninvasive tool in the study of edema and ecchymosis and can be used to document these chromophores in vivo and determine the efficacy of treatments in a clinical setting.
2016-01-01
Age-related neuromuscular change of Tibialis Anterior (TA) is a leading cause of muscle strength decline among the elderly. This study has established the baseline for age-associated changes in sEMG of TA at different levels of voluntary contraction. We have investigated the use of Gaussianity and maximal power of the power spectral density (PSD) as suitable features to identify age-associated changes in the surface electromyogram (sEMG). Eighteen younger (20–30 years) and 18 older (60–85 years) cohorts completed two trials of isometric dorsiflexion at four different force levels between 10% and 50% of the maximal voluntary contraction. Gaussianity and maximal power of the PSD of sEMG were determined. Results show a significant increase in sEMG's maximal power of the PSD and Gaussianity with increase in force for both cohorts. It was also observed that older cohorts had higher maximal power of the PSD and lower Gaussianity. These age-related differences observed in the PSD and Gaussianity could be due to motor unit remodelling. This can be useful for noninvasive tracking of age-associated neuromuscular changes. PMID:27610379
Siddiqi, Ariba; Arjunan, Sridhar Poosapadi; Kumar, Dinesh Kant
2016-01-01
Age-related neuromuscular change of Tibialis Anterior (TA) is a leading cause of muscle strength decline among the elderly. This study has established the baseline for age-associated changes in sEMG of TA at different levels of voluntary contraction. We have investigated the use of Gaussianity and maximal power of the power spectral density (PSD) as suitable features to identify age-associated changes in the surface electromyogram (sEMG). Eighteen younger (20-30 years) and 18 older (60-85 years) cohorts completed two trials of isometric dorsiflexion at four different force levels between 10% and 50% of the maximal voluntary contraction. Gaussianity and maximal power of the PSD of sEMG were determined. Results show a significant increase in sEMG's maximal power of the PSD and Gaussianity with increase in force for both cohorts. It was also observed that older cohorts had higher maximal power of the PSD and lower Gaussianity. These age-related differences observed in the PSD and Gaussianity could be due to motor unit remodelling. This can be useful for noninvasive tracking of age-associated neuromuscular changes. PMID:27610379
NASA Astrophysics Data System (ADS)
Reininger, Ruben; de Castro, A. R. B.
2005-02-01
We give a unified discussion of two different approaches to the design of grazing incidence monochromators with a variable line spacing (VLS) grating for soft X-ray undulator sources. Neither one uses an entrance slit and both work with a fixed position exit slit. In one approach, being constructed at LNLS and designed for the energy range 100
Spin Doublet Point Defects in Graphenes: Predictions for ESR and NMR Spectral Parameters.
Vähäkangas, Jarkko; Lantto, Perttu; Mareš, Jiří; Vaara, Juha
2015-08-11
An adatom on a graphene surface may carry a magnetic moment causing spin-half paramagnetism. This theoretically predicted phenomenon has recently also been experimentally verified. The measurements of defect-induced magnetism are mainly based on magnetometric techniques where artifacts such as environmental magnetic impurities are hard to rule out. Spectroscopic methods such as electron spin resonance (ESR) and paramagnetic nuclear magnetic resonance (pNMR) are conventionally used in the development of magnetic materials, e.g., to study paramagnetic centers. The present density functional theory study demonstrates with calculations of the ESR g-tensor and the hyperfine coupling tensors, as well as the pNMR shielding tensor, that these spectroscopies can be used to identify the paramagnetic centers in graphenes. The studied defects are hydrogen and fluorine adatoms on sp(2)-hybridized graphene, as well as hydrogen and fluorine vacancies in the sp(3)-hybridized graphane and fluorographene, respectively. The directly measurable ESR and pNMR parameters give insight into the electronic and atomic structures of these defects and may contribute to understanding carbon-based magnetism via the characterization of the defect centers. We show that missing hydrogen and fluorine atoms in the functionalized graphane and fluorographene, respectively, constitute sp(2)-defect centers, in which the magnetic resonance parameters are greatly enhanced. Slowly decaying adatom-induced magnetic resonance parameters with the distance from the sp(3)-defect, are found in pure graphene. PMID:26574457
New atmospheric parameters and spectral interpolator for the MILES cool stars
NASA Astrophysics Data System (ADS)
Sharma, Kaushal; Prugniel, Philippe; Singh, Harinder P.
2016-01-01
Context. The full spectrum fitting of stellar spectra against a library of empirical spectra is a well-established approach to measure the atmospheric parameters of FGK stars with a high internal consistency. Extending it towards cooler stars still remains a challenge. Aims: We address this question by improving the interpolator of the Medium-resolution INT Library of Empirical Spectra (MILES) library in the low effective temperature regime (Teff < 4800 K), and we refine the determination of the parameters of the cool MILES stars. Methods: We use the ULySS package to determine the atmospheric parameters (Teff, log g and [Fe/H]), and measure the biases of the results with respect to our updated compilation of parameters calibrated against theoretical spectra. After correcting some systematic effects, we compute a new interpolator that we finally use to redetermine the atmospheric parameters homogeneously and assess the biases. Results: Based on an updated literature compilation, we determine Teff in a more accurate and unbiased manner compared to those determined with the original interpolator. The validity range is extended downwards to about Teff= 2900 K compared to 3500 K previously. The mean residual biases on Teff, log g, and [Fe/H], with respect to the literature compilation for the coolest stars (Teff ≤ 3800 K) computed using the new interpolator, are -15 K, -0.02 dex, and 0.02 dex respectively. The corresponding estimations of the external precision are 63 K, 0.23 dex, and 0.15 dex respectively. For the stars with Teff in the range 3800-4200 K, the determinations of Teff and [Fe/H] have been slightly improved. At higher temperatures, the new interpolator is comparable to the original one. The new version of the interpolator is publicly available. The model as a FITS file is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/585/A64
Abdallah, Zeina; Boucher, Yann G; Fernandez, Arnaud; Balac, Stéphane; Llopis, Olivier
2016-01-01
A microwave domain characterization approach is proposed to determine the properties of high quality factor optical resonators. This approach features a very high precision in frequency and aims to acquire a full knowledge of the complex transfer function (amplitude and phase) characterizing an optical resonator using a microwave vector network analyzer. It is able to discriminate between the different coupling regimes, from the under-coupling to the selective amplification, and it is used together with a model from which the main resonator parameters are extracted, i.e. coupling factor, intrinsic losses, phase slope, intrinsic and external quality factor. PMID:27251460
NASA Astrophysics Data System (ADS)
Abdallah, Zeina; Boucher, Yann G.; Fernandez, Arnaud; Balac, Stéphane; Llopis, Olivier
2016-06-01
A microwave domain characterization approach is proposed to determine the properties of high quality factor optical resonators. This approach features a very high precision in frequency and aims to acquire a full knowledge of the complex transfer function (amplitude and phase) characterizing an optical resonator using a microwave vector network analyzer. It is able to discriminate between the different coupling regimes, from the under-coupling to the selective amplification, and it is used together with a model from which the main resonator parameters are extracted, i.e. coupling factor, intrinsic losses, phase slope, intrinsic and external quality factor.
Abdallah, Zeina; Boucher, Yann G.; Fernandez, Arnaud; Balac, Stéphane; Llopis, Olivier
2016-01-01
A microwave domain characterization approach is proposed to determine the properties of high quality factor optical resonators. This approach features a very high precision in frequency and aims to acquire a full knowledge of the complex transfer function (amplitude and phase) characterizing an optical resonator using a microwave vector network analyzer. It is able to discriminate between the different coupling regimes, from the under-coupling to the selective amplification, and it is used together with a model from which the main resonator parameters are extracted, i.e. coupling factor, intrinsic losses, phase slope, intrinsic and external quality factor. PMID:27251460
Methane spectral line widths and shifts, and dependences on physical parameters
NASA Technical Reports Server (NTRS)
Fox, K.; Quillen, D. T.; Jennings, D. E.; Wagner, J.; Plymate, C.
1991-01-01
A detailed report of the recent high-resolution spectroscopic research on widths and shifts measured for a strong infrared-active fundamental of methane is presented. They were measured in collision with several rare gases and diatomic molecules, in the vibrational-rotational fundamental near 3000/cm. These measurements were made at an ambient temperature of 294 K over a range of pressures from 100 to 700 torr. The measurements are discussed in a preliminary but detailed and quantitative manner with reference to masses, polarizabilities, and quadrupole moments. Some functional dependences on these physical parameters are considered. The present data are useful for studies of corresponding planetary spectra.
NASA Technical Reports Server (NTRS)
Albert, Karen Keppler
1999-01-01
Pressure broadening and pressure-induced shift coefficients due to water and nitrogen have been determined for water vapor transitions in the CO2 region of interest to Project HALOE. The temperature dependences of the widths and shifts have also been determined for selected transitions in this region. Results have been compared with values available in the literature. The line parameters have been obtained from the analysis of room temperature recordings of the spectrum of pure water and recordings of the spectra of heated water/nitrogen mixtures. The recordings of the water vapor spectrum were obtained with Fourier Transform Spectrometers at Kitt Peak and at the Justus-Liebig-Universitat Giessen. Up to eighteen spectra have been fitted simultaneously with a multispectrum nonlinear least-squares fitting technique developed by Dr. D. Chris Benner and colleagues.
Dependence of the spectral parameters of a Raman fibre laser on the Bragg grating temperature
Babin, S A; Potapov, V V; Churkin, D V; Kurkov, Andrei S
2003-12-31
Changes in the output power and emission spectrum of a two-stage Raman phosphosilicate fibre laser are measured during the temperature tuning of fibre Bragg gratings (FBGs) forming enclosed resonators (1.26/1.52 {mu}m). The output emission spectrum of the dense resonator (1.26 {mu}m) is split into two components, whose relative amplitudes change during the temperature tuning of FBGs. A simple analytic model is constructed which describes the broadening and splitting of the spectrum as well as the appearance of its asymmetry upon the relative detuning of FBGs. It is shown that these effects result in the increase in the effective transmission coefficient of the dense resonator at least by an order of magnitude, which affects the output power of the Raman laser. (control of laser radiation parameters)
NASA Astrophysics Data System (ADS)
Mugnes, J.-M.; Robert, C.
2015-11-01
Spectral analysis is a powerful tool to investigate stellar properties and it has been widely used for decades now. However, the methods considered to perform this kind of analysis are mostly based on iteration among a few diagnostic lines to determine the stellar parameters. While these methods are often simple and fast, they can lead to errors and large uncertainties due to the required assumptions. Here, we present a method based on Bayesian statistics to find simultaneously the best combination of effective temperature, surface gravity, projected rotational velocity, and microturbulence velocity, using all the available spectral lines. Different tests are discussed to demonstrate the strength of our method, which we apply to 54 mid-resolution spectra of field and cluster B stars obtained at the Observatoire du Mont-Mégantic. We compare our results with those found in the literature. Differences are seen which are well explained by the different methods used. We conclude that the B-star microturbulence velocities are often underestimated. We also confirm the trend that B stars in clusters are on average faster rotators than field B stars.
NASA Astrophysics Data System (ADS)
Tang, Jian; Yu, Wen; Chai, Tianyou; Liu, Zhuo; Zhou, Xiaojie
2016-01-01
It is difficult to model multi-frequency signal, such as mechanical vibration and acoustic signals of wet ball mill in the mineral grinding process. In this paper, these signals are decomposed into multi-scale intrinsic mode functions (IMFs) by the empirical mode decomposition (EMD) technique. A new adaptive multi-scale spectral features selection approach based on sphere criterion (SC) is applied to these IMFs frequency spectra. The candidate sub-models are constructed by the partial least squares (PLS) with the selected features. Finally, the branch and bound based selective ensemble (BBSEN) algorithm is applied to select and combine these ensemble sub-models. This method can be easily extended to regression and classification problems with multi-time scale signal. We successfully apply this approach to a laboratory-scale ball mill. The shell vibration and acoustic signals are used to model mill load parameters. The experimental results demonstrate that this novel approach is more effective than the other modeling methods based on multi-scale frequency spectral features.
NASA Astrophysics Data System (ADS)
Zhang, Yu; Zuo, Yan; Pan, Feng; Draayer, J. P.
2016-04-01
The spectral characteristics of the Lπ=0+ excited states in the interacting boson model are systematically investigated. It is found that various types of excited-state quantum phase transitions may widely occur in the model as functions of the excitation energy, which indicates that the phase diagram of the interacting boson model can be dynamically extended along the direction of the excitation energy. It has also been justified that the d -boson occupation probability ρ (E ) is qualified to be taken as the effective order parameter to identify these excited-state quantum phase transitions. In addition, the underlying relation between the excite-state quantum phase transition and the chaotic dynamics is also stated.
Serio, Carmine; Masiello, Guido; Liuzzi, Giuliano
2016-08-20
The random projections statistical technique has been used to reduce the dimensionality of the radiance data space generated from high spectral resolution infrared observations. The mathematical inversion of the physical radiative transfer equation for geophysical parameters has been solved in this space of reduced dimensionality. The great advantage of using random projections is that they provide an unified treatment of instrument noise and forward model error, which can be comprehensively modeled with a single variance term. The result is a novel retrieval approach, which combines computational efficiency to possibly improved accuracy of the retrieval products. The novel approach has been demonstrated through application to the Infrared Atmospheric Sounding Interferometer. We have found that state-of-the-art spectroscopy and related line-mixing treatment for the ν_{2}CO_{2} absorption band, i.e., the fundamental band for temperature retrieval, show an excellent consistency with satellite observations. PMID:27556974
Bongers, Mathilda L; de Ruysscher, Dirk; Oberije, Cary; Lambin, Philippe; Uyl-de Groot, Carin A; Coupé, V M H
2016-01-01
With the shift toward individualized treatment, cost-effectiveness models need to incorporate patient and tumor characteristics that may be relevant to treatment planning. In this study, we used multistate statistical modeling to inform a microsimulation model for cost-effectiveness analysis of individualized radiotherapy in lung cancer. The model tracks clinical events over time and takes patient and tumor features into account. Four clinical states were included in the model: alive without progression, local recurrence, metastasis, and death. Individual patients were simulated by repeatedly sampling a patient profile, consisting of patient and tumor characteristics. The transitioning of patients between the health states is governed by personalized time-dependent hazard rates, which were obtained from multistate statistical modeling (MSSM). The model simulations for both the individualized and conventional radiotherapy strategies demonstrated internal and external validity. Therefore, MSSM is a useful technique for obtaining the correlated individualized transition rates that are required for the quantification of a microsimulation model. Moreover, we have used the hazard ratios, their 95% confidence intervals, and their covariance to quantify the parameter uncertainty of the model in a correlated way. The obtained model will be used to evaluate the cost-effectiveness of individualized radiotherapy treatment planning, including the uncertainty of input parameters. We discuss the model-building process and the strengths and weaknesses of using MSSM in a microsimulation model for individualized radiotherapy in lung cancer. PMID:25732723
Chandran, Senthilkumar; Jagan, R.; Paulraj, Rajesh; Ramasamy, P.
2015-10-15
Metal-organic bis(hydrogenmaleate)-Co(II) tetrahydrate single crystals have been grown by slow evaporation solution growth technique at room temperature. The crystal structure and the unit cell parameters were analyzed from the X-ray diffraction studies. Single-crystal X-ray diffraction analyses reveal that the grown crystal belongs to triclinic system with the space group P-1. Functional groups in bis(hydrogenmaleate)-Co(II) tetrahydrate were identified by Fourier transform infrared spectral analysis. The peak observed at 663 cm{sup −1} is assigned to the (Co–O) stretching vibrations. The optical transmission of the crystal was studied by UV–vis–NIR spectral analysis. The photoluminescence emission studies were carried out for the title compound in a wide wavelength range between 350 nm and 550 nm at 303 K. Mechanical strength was tested by Vickers microhardness test. The laser damage threshold value has been determined using Nd:YAG laser operating at 1064 nm. At various frequencies and temperatures the dielectric behavior of the material was investigated. Solid state parameters such as plasma energy, Penn gap, Fermi energy and electronic polarizability were evaluated. Photoconductivity measurements were carried out for the grown crystal in the presence of DC electric field at room temperature. Thermal stability and decomposition of the crystal were studied by TG–DTA. The weight loss of the title compound occurs in different steps. - Graphical abstract: Molecular structure of the bis(hydrogenmaleate)-Co(II) tetrahydrate drawn at 40% ellipsoid probability level. - Highlights: • Bis(hydrogenmaleate)-Co(II) tetrahydrate single crystal is grown by slow evaporation method. • Structural and optical properties were discussed. • The title complex crystal is thermally stable up to 91 °C. • Plasma energy, Fermi energy and electronic polarizability are evaluated. • It exhibits positive photoconductivity.
NASA Astrophysics Data System (ADS)
Longobardo, Andrea; Palomba, Ernesto; Capaccioni, Fabrizio; De Sanctis, Maria Cristina; Tosi, Federico; Ammannito, Eleonora; Schröder, Stefan E.; Zambon, Francesca; Raymond, Carol A.; Russell, Christopher T.
2014-09-01
NASA’s Dawn spacecraft orbited Vesta for approximately one year, collecting thousands of hyperspectral images of its surface. The mission revealed that Vesta’s surface shows the largest variations in surface albedo on asteroids visited thus far, due to the presence of dark and bright materials at the local scale (i.e. 0.1-10 km). The aim of this work is to characterize the photometric properties of bright and dark regions, and thus derive and apply an empirical photometric correction to all the hyperspectral observations of Vesta. The very large dataset (i.e. more than 20 million spectra) provided by the VIR imaging spectrometer onboard Dawn enabled accurate statistical analysis of the spectral dataset, aimed at retrieving empirical relations between several spectral parameters (i.e. visible and infrared reflectance, band depths, band centers, Band Area Ratio) and the illumination/viewing angles. The derived relations made it possible to derive photometrically corrected maps of these spectral parameters and to infer information on the regolith shadowing effect in the Vestan dark and bright regions. As an additional analysis, we also evaluated the correlation between surface temperature and band center position. A general conclusion of this analysis is that, from a photometric point of view, the distinction between bright and dark material units lies mainly in the larger contribution due to multiple scattering in the bright units. We observed reflectance and band depth variations over Vesta’s entire surface, but these variations were much larger in the dark regions than in the bright ones. Band centers have been found to shift to longer wavelengths at increasing temperatures, with a trend that is the same observed for HED meteorites (Reddy et al. [2012]. Icarus 217, 153-158). Finally, the Band Area Ratio (i.e. the ratio between areas of the main pyroxene absorption bands located at 1.9 μm and at 0.9 μm, respectively) did not show any dependence on
NASA Astrophysics Data System (ADS)
Devi, V. Malathy; Benner, D. Chris; Sung, Keeyoon; Brown, Linda R.; Crawford, Timothy J.; Miller, Charles E.; Drouin, Brian J.; Payne, Vivienne H.; Yu, Shanshan; Smith, Mary Ann H.; Mantz, Arlan W.; Gamache, Robert R.
2016-07-01
Pressure-broadened line shapes in the 30013←00001 (ν1+4 ν20 +ν3) band of 12C16O2 at 6228 cm-1 are reanalyzed using new spectra recorded with sample temperatures down to 170 K. High resolution, high signal-to-noise (S/N) laboratory measurements of line shapes (Lorentz air- and self-broadened half-width coefficients, pressure-shift coefficients and off-diagonal relaxation matrix element coefficients) as a function of gas sample temperatures for various pressures and volume mixing ratios are presented. The spectra were recorded using two different Fourier transform spectrometers (FTS): (1) the McMath-Pierce FTS located at the National Solar Observatory on Kitt Peak, Arizona (and reported in Devi et al., J Mol Spectrosc 2007;245:52-80) and, (2) the Bruker IFS-125HR FTS at the Jet Propulsion Laboratory in Pasadena, California. The 19 spectra taken at Kitt Peak were all recorded near room temperature while the 27 Bruker spectra were acquired both at room temperature and colder temperatures (170-296 K). Various spectral resolutions (0.004-0.011 cm-1), absorption path lengths (2.46-121 m) and CO2 samples (natural and 12C-enriched) were included in the dataset. To maximize the accuracies of the various retrieved line parameters, a multispectrum nonlinear least squares spectrum fitting software program was used to adjust the ro-vibrational constants (G,B,D etc.) and intensity parameters (including Herman-Wallis terms) instead of directly measuring the individual line positions and intensities. To minimize systematic residuals, line mixing (via off-diagonal relaxation matrix elements) and quadratic speed dependence parameters were included in the analysis. Contributions from other weakly absorbing bands: the 30013←00001 and 30012←00001 bands of 13C16O2, the 30013←00001 band of 12C16O18O, hot bands 31113←01101 and 32212←02201 of 12C16O2, as well as the 40013←10001 and the 40014←10002 bands of 12C16O2, present within the fitted interval were also measured
Voitsekhovskaya, O K; Egorov, O V; Kashirskii, D E
2016-08-01
Nitrogen dioxide, (14)N(16)O2, line positions and intensities calculated by us based on a "local" effective operator method are compared to the recent results of the "global" calculation. The comparison was made for theoretical absorption coefficients in the spectral range of 600-3700cm(-1) using the measured data taken from the Pacific Northwest National Laboratory. In order to conduct the calculations, empirical parameters of the effective rotational Hamiltonian of the twenty-one vibrational states were applied from the most recent experimental works. The second order parameters of the dipole moment function of (14)N(16)O2 were determined for the first time. The "local" line list in this research consists of one hundred and four bands and includes the line intensities of the v1+v2+v3 band of (14)N(16)O2 that have not yet been investigated in the literature. Among these bands, only eleven bands are included in HITRAN2012. The reasons behind the disagreements between the theoretical and measured absorption coefficients of (14)N(16)O2 are discussed. PMID:27111152
NASA Astrophysics Data System (ADS)
Voitsekhovskaya, O. K.; Egorov, O. V.; Kashirskii, D. E.
2016-08-01
Nitrogen dioxide, 14N16O2, line positions and intensities calculated by us based on a "local" effective operator method are compared to the recent results of the "global" calculation. The comparison was made for theoretical absorption coefficients in the spectral range of 600-3700 cm- 1 using the measured data taken from the Pacific Northwest National Laboratory. In order to conduct the calculations, empirical parameters of the effective rotational Hamiltonian of the twenty-one vibrational states were applied from the most recent experimental works. The second order parameters of the dipole moment function of 14N16O2 were determined for the first time. The "local" line list in this research consists of one hundred and four bands and includes the line intensities of the v1 + v2 + v3 band of 14N16O2 that have not yet been investigated in the literature. Among these bands, only eleven bands are included in HITRAN2012. The reasons behind the disagreements between the theoretical and measured absorption coefficients of 14N16O2 are discussed.
NASA Astrophysics Data System (ADS)
Gorbunova, Elena V.; Chertov, Aleksandr N.; Peretyagin, Vladimir S.; Lastovskaia, Elena A.; Korotaev, Valery V.
2015-03-01
Quality control of different coatings (colorful, paint, marker, safety, etc.) that are applied to the surface of various objects (both metallic and non-metallic) is an important problem. Also, there is a problem of dealing with counterfeit products. So it's necessary to distinguish the fake replicas of marking from the authentic marking of producer. To solve these problems, we propose an automated apparatus for analysis and control of spectral reflection characteristics, albedo and color parameters of extended (up to 150 mm × 150 mm) flat objects. It allows constructing the color image of the object surface as well as its multispectral images in different regions of the spectrum. Herewith the color of the object surface can be calculated for various standard light sources (A, B, C, D65, E, F2, F7, F11, GE), or to any light source with a predetermined emission spectrum. The paper presents the description of working principles of the proposed apparatus as well as the results of reflection and multispectral analysis of different flat objects.
NASA Astrophysics Data System (ADS)
Hirose, Misa; Akaho, Rina; Maita, Chikashi; Sugawara, Mai; Tsumura, Norimichi
2016-06-01
In this paper, the spectral sensitivities of a mosaic five-band camera were optimized using a numerical skin phantom to perform the separation of chromophore densities, shading and surface reflection. To simulate the numerical skin phantom, the spectral reflectance of skin was first calculated by Monte Carlo simulation of photon migration for different concentrations of melanin, blood and oxygen saturation levels. The melanin and hemoglobin concentration distributions used in the numerical skin phantom were obtained from actual skin images by independent component analysis. The calculated components were assigned as concentration distributions. The spectral sensitivities of the camera were then optimized using a nonlinear technique to estimate the spectral reflectance for skin separation. In this optimization, the spectral sensitivities were assumed to be normally distributed, and the sensor arrangement was identical to that of a conventional mosaic five-band camera. Our findings demonstrated that spectral estimation could be significantly improved by optimizing the spectral sensitivities.
NASA Astrophysics Data System (ADS)
Hirose, Misa; Akaho, Rina; Maita, Chikashi; Sugawara, Mai; Tsumura, Norimichi
2016-02-01
In this paper, the spectral sensitivities of a mosaic five-band camera were optimized using a numerical skin phantom to perform the separation of chromophore densities, shading and surface reflection. To simulate the numerical skin phantom, the spectral reflectance of skin was first calculated by Monte Carlo simulation of photon migration for different concentrations of melanin, blood and oxygen saturation levels. The melanin and hemoglobin concentration distributions used in the numerical skin phantom were obtained from actual skin images by independent component analysis. The calculated components were assigned as concentration distributions. The spectral sensitivities of the camera were then optimized using a nonlinear technique to estimate the spectral reflectance for skin separation. In this optimization, the spectral sensitivities were assumed to be normally distributed, and the sensor arrangement was identical to that of a conventional mosaic five-band camera. Our findings demonstrated that spectral estimation could be significantly improved by optimizing the spectral sensitivities.
NASA Astrophysics Data System (ADS)
Shah, S. H.; Houborg, R.; Tester, M.; McCabe, M. F.
2014-12-01
Multidisciplinary research has long sought the ability to estimate the parameters of plant functions such as photosynthetic capacity under stress conditions from remotely sensed data. Yet, the main goal has not been fully elucidated. In this study, we investigated the effects of saline water irrigation and the rate of fertilizer application on the photosynthetic response of wheat in a greenhouse based experiment. After two weeks of germination, the plants were subjected to irrigation with sea water blended with high quality reverse osmosis (RO) water. Three levels of water salinity having electrical conductivities (EC) of 0.3, 7.0, 14.0 dSm-1 were obtained by mixing sea water with RO water and plants were irrigated to approximately 70% of field capacity without excess drainage. Three levels of NPK fertilizer at the rate of null, half and full recommended doses were also employed in the experiment. The two key determinants of photosynthetic capacity, the maximum rates of RuBP carboxylation (Vcmax) and the maximum rate of photosynthetic electron transport based on NADPH requirement (Jmax), were obtained through standard gas exchange technique.CO2 response curves of net CO2 assimilation (An) against variable CO2 concentrations in the intracellular spaces (Ci) at constant environmental conditions were drawn and a Sharkey model was fit to the obtained data. Hyperspectral reflectance (λ = 350-2500 nm) of fresh leaves were obtained and the hyperspectral characteristics and their correlations with the photosynthetic parameters were drawn. Unique contributions from different spectral regions of the hyperspectral data were analyzed. Our results revealed that saline irrigation adversely affects some of the biochemical photosynthetic parameters while favors others and it can be reflected in shifts in patterns at various regions of the hyperspectral data. These results suggest a promising strategy for developing remote sensing methods to characterize photosynthetic activity of
Kaganov, A Sh
2014-01-01
The objective of the present study was to elucidate the relationship between the spectral speech characteristics and the biometric parameters of the speaker's vocal tract. The secondary objective was to consider the theoretical basis behind the medico-criminalistic personality identification from the biometric parameters of the speaker's vocal tract. The article is based on the results of real forensic medical investigations and the literature data. PMID:25275181
Audren, Benjamin; Lesgourgues, Julien; Bird, Simeon; Haehnelt, Martin G.; Viel, Matteo E-mail: julien.lesgourgues@cern.ch E-mail: haehnelt@ast.cam.ac.uk
2013-01-01
We present forecasts for the accuracy of determining the parameters of a minimal cosmological model and the total neutrino mass based on combined mock data for a future Euclid-like galaxy survey and Planck. We consider two different galaxy surveys: a spectroscopic redshift survey and a cosmic shear survey. We make use of the Monte Carlo Markov Chains (MCMC) technique and assume two sets of theoretical errors. The first error is meant to account for uncertainties in the modelling of the effect of neutrinos on the non-linear galaxy power spectrum and we assume this error to be fully correlated in Fourier space. The second error is meant to parametrize the overall residual uncertainties in modelling the non-linear galaxy power spectrum at small scales, and is conservatively assumed to be uncorrelated and to increase with the ratio of a given scale to the scale of non-linearity. It hence increases with wavenumber and decreases with redshift. With these two assumptions for the errors and assuming further conservatively that the uncorrelated error rises above 2% at k = 0.4 h/Mpc and z = 0.5, we find that a future Euclid-like cosmic shear/galaxy survey achieves a 1-σ error on M{sub ν} close to 32 meV/25 meV, sufficient for detecting the total neutrino mass with good significance. If the residual uncorrelated errors indeed rises rapidly towards smaller scales in the non-linear regime as we have assumed here then the data on non-linear scales does not increase the sensitivity to the total neutrino mass. Assuming instead a ten times smaller theoretical error with the same scale dependence, the error on the total neutrino mass decreases moderately from σ(M{sub ν}) = 18 meV to 14 meV when mildly non-linear scales with 0.1 h/Mpc < k < 0.6 h/Mpc are included in the analysis of the galaxy survey data.
NASA Technical Reports Server (NTRS)
Adams, J. C., Jr.; Martindale, W. R.; Mayne, A. W., Jr.; Marchand, E. O.
1976-01-01
Inviscid and viscous (laminar boundary-layer) flow-field calculations under perfect gas hypersonic wind tunnel and equilibrium real gas flight conditions are presented for the windward centerline of the Rockwell International 139 Space Shuttle Orbiter at a 30-deg angle of attack. Correlation parameters for laminar boundary-layer edge quantities and surface heat transfer are developed which properly account for entropy-layer-swallowing effects under both real and perfect gas conditions. Some implications of the proposed correlation parameters on boundary-layer transition are discussed.
Bendangsenla, N; Moaienla, T; David Singh, Th; Sumitra, Ch; Rajmuhon Singh, N; Indira Devi, M
2013-02-15
The interactions of Pr(III) with nucleosides and nucleotides have been studied in different organic solvents employing absorption difference and comparative absorption spectrophotometry. The magnitudes of the variations in both energy and intensity interaction parameters were used to explore the degree of outer and inner sphere co-ordination, incidence of covalency and the extent of metal 4f-orbital involvement in chemical bonding. Various electronic spectral parameters like Slater-Condon (F(k)), Racah (E(k)), Lande parameter (ξ(4f)), Nephelauxatic ratio (β), bonding (b(1/2)), percentage covalency (δ) and intensity parameters like oscillator strength (P) and Judd Ofelt electronic dipole intensity parameter (T(λ), λ=2,4,6) have been evaluated. The variation of these evaluated parameters were employed to interpret the nature of binding of Pr(III) with different ligands i.e. Adenosine/ATP in presence and absence of Ca(2+). PMID:23257345
Vinogradoff, Susan I; Oliver, Ian W
2015-01-01
Under the Water Framework Directive (WFD) lakes are classified according to a variety of criteria. This classification facilitates state of the environment assessments and helps identify work needed to achieve the objectives of the WFD, which are broadly to maintain and/or restore water quality and ecological status at a level recognised as good or high. To achieve high or good status, lakes must meet a criterion for total phosphorus (TP) that is linked to a predicted reference condition value that is derived by various models. Lakes which fail to meet good status may require expensive remedial actions to be undertaken, thus accurate identification of the reference condition TP concentration is vital for effective environmental management. However, the models currently employed could be improved for some regions, particularly those with carbon rich soils. By examining 19 reference condition lakes (i.e. lakes essentially non-impacted by humans) in peaty areas of Scotland, we found that a simple parameter linked to water colour and humic substances was a better predictor of TP than the currently employed models (R(2) 0.585 vs R(2) < 0.01). Therefore, for Scotland and elsewhere, in regions with carbon rich soils and lakes with humic waters the TP predictive models could be improved by development and incorporation of a parameter related to water colour and humic components. PMID:25262390
Spectral shape parameters of pure CO2 transitions near 1.6 μm by tunable diode laser spectroscopy
NASA Astrophysics Data System (ADS)
Larcher, G.; Landsheere, X.; Schwell, M.; Tran, H.
2015-10-01
Room temperature spectra of four lines of pure CO2 in the 1.6 μm region have been measured in a wide range of pressure using a tunable diode laser spectrometer. The spectra of each line have been adjusted using a multi-spectrum fitting procedure with various line-shape models, including the recently recommended Hartmann-Tran profile (HTP). The results show that the collision-induced velocity changes and the speed-dependence effects are clearly observed. It is also shown that taking into account the correlation between velocity- and internal state-changes is necessary to obtain physically-meaningful line-shape parameters. The latter are reported and discussed.
Patrick, Sean M; Bornman, Maria S; Joubert, Annie M; Pitts, Neville; Naidoo, Vinny; de Jager, Christiaan
2016-06-01
The male reproductive system is sensitive to endocrine disrupting chemicals (EDCs) during critical developmental windows. Male Sprague-Dawley rats were exposed in utero-, during lactation- and directly to 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT), 1,1,-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE) and a mixture of DDT, deltamethrin (DM), p-nonylphenol (p-NP) and phytoestrogens, at concentrations found in a malaria-area. After dosing for 104 days, histological assessments and reproductive-endpoints were assessed. The anogenital distance (AGD) (P=0.005) was shorter in the mixture-exposed group, while the prostate mass (P=0.018) was higher in the DDT-exposed group. A higher testicular mass and abnormal histology was observed in the DDT-(P=0.019), DDE-(P=0.047) and mixture-exposed (P<0.005) groups. This study shows that in utero-, lactational- and direct exposure to EDCs present in a malaria-area negatively affects male reproductive parameters in rats. These findings raise concerns to EDC-exposures to mothers living in malaria-areas and the reproductive health of their male offspring. PMID:26928317
NASA Astrophysics Data System (ADS)
Heißerer, T.; Haslauer, C. P.; Bárdossy, A.
2016-04-01
Most groundwater recharge comes from the infiltration of water through the land surface. Data analysis shows that solute concentrations at the water table vary between land use categories and depending on the land use composition within a certain neighbourhood. Driven by these observations, the goal of this paper is to estimate the solute distribution at a location depending on the composition of land use in the neighbourhood, even though land use information is categorical. This goal is achieved by mixing pure distributions of homogeneous land use according to their frequency of occurrence in the vicinity of, and their distance from an estimation location. These pure distributions are jointly inverted using a maximum likelihood-based approach. The neighbourhood size is optimized using cross-validation. Measurements below detection limit are included via their probabilities of non-exceedance. A solute-specific, spatially distributed measure of information content of the secondary information is presented. The method is applicable for many types of secondary information and can be used as drift for spatial estimation of the primary variable. This estimation is a local estimation and does not include larger scale spatial information. The information of measurements is included via the optimized concentration distributions for land use groups, not via a model of spatial dependence. The global estimation is described in the companion paper.
NASA Astrophysics Data System (ADS)
Lafrenière-Bérubé, Charles; Chouteau, Michel; Shamsipour, Pejman; Olivo, Gema R.
2016-04-01
Spectral induced polarization (SIP) parameters can be extracted from field or laboratory complex resistivity measurements, and even airborne or ground frequency domain electromagnetic data. With the growing interest in application of complex resistivity measurements to environmental and mineral exploration problems, there is a need for accurate and easy-to-use inversion tools to estimate SIP parameters. These parameters, which often include chargeability and relaxation time may then be studied and related to other rock attributes such as porosity or metallic grain content, in the case of mineral exploration. We present an open source program, available both as a standalone application or Python module, to estimate SIP parameters using Markov-chain Monte Carlo (MCMC) sampling. The Python language is a high level, open source language that is now widely used in scientific computing. Our program allows the user to choose between the more common Cole-Cole (Pelton), Dias, or Debye decomposition models. Simple circuits composed of resistances and constant phase elements may also be used to represent SIP data. Initial guesses are required when using more classic inversion techniques such as the least-squares formulation, and wrong estimates are often the cause of bad curve fitting. In stochastic optimization using MCMC, the effect of the starting values disappears as the simulation proceeds. Our program is then optimized to do batch inversion over large data sets with as little user-interaction as possible. Additionally, the Bayesian formulation allows the user to do quality control by fully propagating the measurement errors in the inversion process, providing an estimation of the SIP parameters uncertainty. This information is valuable when trying to relate chargeability or relaxation time to other physical properties. We test the inversion program on complex resistivity measurements of 12 core samples from the world-class gold deposit of Canadian Malartic. Results show
NASA Astrophysics Data System (ADS)
Fan, Fenglei; Deng, Yingbin
2015-04-01
Since publication, the authors have been advised of one prior methodological article not cited in our original paper. The missed reference from the paper is "Andreou, C., Karathanassi, V., 2012. A novel multiple endmember spectral mixture analysis using spectral angle distance. Geoscience and Remote Sensing Symposium (IGARSS) 2012 IEEE International, 4110-4113." This reference "Andreou, C., Karathanassi, V., 2012 in proceeding of IGARSS" should be cited in the Part 3 and Table 1, whereby in the fist sentence of Part 3 and the last sentence of caption of Table 1. The following should be added (in Part 3: According to the traditional MESMA and referring to MESMA-SAD method which is reported by Andreou and Karathanassi; in caption of Table 1: Based on the MESMA-SAD method of Andreou and Karathanassi). We apologize to the authors and workers concerned for this oversight and are pleased to acknowledge their contributions.
NASA Astrophysics Data System (ADS)
Haslauer, C. P.; Heißerer, T.; Bárdossy, A.
2016-04-01
Two dominant processes determine solute concentration in groundwater: vertical infiltration and horizontal advection. The goal of this paper is to incorporate both processes into a geostatistical model for spatial estimation of solute concentrations in groundwater. A multivariate copula-based methodology is demonstrated that considers infiltration via the marginal distribution and solute transport via the multivariate spatial dependence structure. The novel approach is compared to traditional methods as Ordinary- and External Drift Kriging. Leave-one-out cross-validation demonstrates that the novel approach estimates better both in concentration and in probability space, and improves the quantification and quality of uncertainty. The gain in uncertainty reduction is equivalent to at least a few hundred additional observations when Ordinary Kriging was used. Both censored and not-censored measurements are included. An ideal neighborhood size is estimated via cross-validation. The methodology is general and can incorporate other kinds of secondary information. It can be used to evaluate effects of land use changes.
Zhang, Tianyu; Fan, Rong; Wang, Zhengting; Hu, Shurong; Zhang, Maochen; Lin, Yun; Tang, Yonghua; Zhong, Jie
2015-01-01
Background: The aim of the study was to evaluate clinical manifestations, T-SPOT, endoscopy and CT enterography to differentiate Crohn’s disease (CD) from intestinal tuberculosis (ITB). Methods: 128 in patients with suspected CD and ITB were prospectively enrolled in the study. Demographic, clinical, laboratory, endoscopic and CT enterographic data were collected. After treatment for 6 months, when a definite diagnosis was reached, the differential diagnostic value of each parameter was analyzed. Multivariable logistic regression was used to analyze further, parameters of statistical significance to establish a mathematical regression equation. Receiver operating characteristic curves were plotted. Results: Clinical parameters helpful in differentiating CD from ITB included diarrhea, night sweat and perianal disease. Endoscopic parameters were useful in differentiating CD from ITB including transverse ulcers, longitudinal ulcers, rodent-like ulcers and patulous ileocecal valve. CT enterographic parameters aided the identification of the two conditions. The sensitivity, specificity, accuracy, positive predictive value and negative predictive value of a mathematical regression model established for 6 parameters of clinical endoscopy and CT enterography were 97.8%, 96.8%, 97.6%, 98.9% and 93.7% respectively, whereas those for T-SPOT were 96.8%, 91.3%, 92.7%, 78.9% and 98.8% respectively. Conclusions: T-SPOT is useful to exclude a diagnosis of ITB. Differentiating CD from ITB is a difficult clinical problem that requires a consideration of clinical, T-SPOT, endoscopic and CT enterographic parameters for accurate diagnosis. PMID:26770348
Nakamae, Mika; Yamashita, Mariko; Koh, Hideo; Nishimoto, Mitsutaka; Hayashi, Yoshiki; Nakane, Takahiko; Nakashima, Yasuhiro; Hirose, Asao; Hino, Masayuki; Nakamae, Hirohisa
2016-06-01
Some studies on the predictive value of determining pulmonary function prior to allogeneic hematopoietic cell transplantation (allo-HCT) have shown a significant association between pulmonary function test (PFT) parameters and pulmonary complications, and mortality. However, the percentage of patients showing abnormalities in pretransplant PFT parameters is low. We comprehensively evaluated the effect of pretransplant PFT parameters, including a marker of small airway disease (ratio of the airflow rate of 50% vital capacity to the airflow rate of 25% vital capacity (V˙50/V˙25), on outcomes in 206 evaluable patients who underwent allo-HCT at our institute. Notable among the significant parameters in a univariable analysis, V˙50/V˙25 was the most powerful indicator of survival following allo-HCT (delta-Akaike information criterion [∆AIC] = 12.47, ∆χ(2) = 14.47; P = 0.0001). Additionally, a pretransplant lung function score (pLFS) established by applying three parameters with superior predictive values including V˙50/V˙25 represented a better discriminating variable for the prediction of survival. Our data demonstrate that a pLFS incorporating a parameter of small airway disease, rather than the parameters of central airway obstruction, may be useful for predicting patient survival following allo-HCT. PMID:27018997
Bodendörfer, Xaver; Kortekaas, Reinier; Weingarten, Markus; Schlittmeier, Sabine
2015-08-01
In human-machine interactions, the confirmation of an action or input is a very important information for users. A paired comparison experiment explored the effects of four acoustic parameters on the perceived confirmation of auditory non-speech signals. Reducing the frequency-ratio and the pulse-to-pulse time between two successive pulses increased perceived confirmation. The effects of the parameters frequency and number of pulses were not clear-cut. The results provide information for designing auditory confirmation signals. It is shown that findings about the effects of certain parameters on the perceived urgency of warning signals cannot be easily inverted to perceived confirmation. PMID:26328737
NASA Astrophysics Data System (ADS)
Ghorbanidehno, H.; Kokkinaki, A.; Darve, E. F.; Kitanidis, P. K.
2014-12-01
The Kalman Filter has been widely used for dynamic monitoring in reservoir engineering, and has recently gained popularity in hydrogeologic applications. A common characteristic of such applications is that the physical processes of interest are greatly affected by preferential flow (e.g., contaminant spreading, CO2 leakage), which can only be delineated if the problem is finely discretized into a large number of unknowns. However, for problems with large numbers of unknowns (e.g., larger than 10,000), the Kalman Filter has prohibitively expensive computation and storage costs. The EnKF, which is typically used to reduce the cost of computing the covariance in such cases converges slowly to the best estimate, and for a reasonable number of realizations, the estimate may not be accurate, especially for strongly heterogeneous systems. We present the Spectral Kalman Filter, a new Kalman Filter implementation that has a dramatically reduced computational cost compared to the full Kalman Filter, with comparable or higher accuracy than the EnKF for the same computational cost. Our algorithm's computational efficiency is achieved by a recurrence that updates small cross-covariance matrices instead of large covariance matrices, in combination with a low-rank approximation of the noise covariance matrix. In addition, instead of computing the expensive Jacobian matrix, a matrix-free method is used to obtain sensitivities. Finally, the error of our method can be explicitly controlled by reducing the time between matrix updates. The frequency of these updates is controlled independently from the data assimilation steps. We demonstrate the performance of the Spectral Kalman Filter for the joint estimation of domain properties and state evolution by assimilation of quasi-continuous data during a hypothetical CO2 injection in a heterogeneous domain.
Koh, Lilian Hui Li; Ismail, Muhammad Amir; Yap, Sae Cheong; Wong, Elizabeth Poh Ying; Yip, Leonard Wei Leon
2016-01-01
AIM To assess the repeatability of measuring optic nerve head (ONH) parameters using the Cirrus optical coherence tomography (OCT), as well as to assess the effect of head tilt on these measurements. METHODS Thirty healthy participants with no evidence of glaucoma were recruited for the study. Visual acuity, intraocular pressure, standard automated perimetry and ocular examination were performed for each participant. One eye was then randomly selected and scanned undilated with the Cirrus OCT in 3 positions (neutral, 30° right tilt and 30° left tilt). RESULTS Data collected from 29 eyes were used for analysis. One patient was omitted due to poor scan quality. The repeatability of the ONH parameters was analyzed using analysis of variance, coefficient of variation (COV) and intraclass correlation coefficient (ICC). Analysis of variance showed no statistically significant difference between 3 scans in a single position. There was good agreement between measurements (ICC 0.919-0.996, COV 1.94%-5.48%). Even with the presence of head tilt, repeated scans in the 3 positions showed good agreement as well (ICC 0.888-0.996, COV 2.04%-5.39%). CONCLUSION Serial measurements of ONH parameters using the Cirrus OCT are found to have good repeatability. The ONH parameters with Cirrus OCT also maintain good repeatability despite head tilt. PMID:27585788
Dopita, M A; Fischera, J; Sutherland, R S; Kewley, L J; Tuffs, R J; Popescu, C C; van Breugel, W; Groves, B A; Leitherer, C
2006-03-01
We examine from a theoretical viewpoint how the physical parameters of H II regions are controlled both in normal galaxies and in starburst environments. These parameters are the H II region luminosity function, the time-dependent size, the covering fraction of molecular clouds, the pressure in the ionized gas and the ionization parameter. The factors which control them are the initial mass function of the exciting stars, the cluster mass function, the metallicity and the mean pressure in the surrounding interstellar medium. We investigate the sensitivity of the H{alpha} luminosity to the IMF, and find that this can translate to about 30% variation in derived star formation rates. The molecular cloud dissipation timescale is estimated from a case study of M17 to be {approx} 1 Myr. Based upon H II luminosity function fitting for nearby galaxies, we propose that the cluster mass function has a log-normal form peaking at {approx} 185M{sub {circle_dot}}. This suggests that the cluster mass function is the continuation of the stellar IMF to higher mass. The pressure in the H II regions is controlled by the mechanical luminosity flux from the central cluster. Since this is closely related to the ionizing photon flux, we show that the ionization parameter is not a free variable, and that the diffuse ionized medium may be composed of many large, faint and old H II regions. Finally, we derive theoretical probability distributions for the ionization parameter as a function of metallicity and compare these to those derived for SDSS galaxies.
NASA Technical Reports Server (NTRS)
Hunt, J. L.; Souders, S. W.
1975-01-01
Normal- and oblique-shock flow parameters for air in thermochemical equilibrium are tabulated as a function of shock angle for altitudes ranging from 15.24 km to 91.44 km in increments of 7.62 km at selected hypersonic speeds. Post-shock parameters tabulated include flow-deflection angle, velocity, Mach number, compressibility factor, isentropic exponent, viscosity, Reynolds number, entropy difference, and static pressure, temperature, density, and enthalpy ratios across the shock. A procedure is presented for obtaining oblique-shock flow properties in equilibrium air on surfaces at various angles of attack, sweep, and dihedral by use of the two-dimensional tabulations. Plots of the flow parameters against flow-deflection angle are presented at altitudes of 30.48, 60.96, and 91.44 km for various stream velocities.
Volz, P A; Long, J D; Veselenak, J M
1995-01-01
Keratinophilic Trichophyton terrestre conidia were exposed to selected parameters of space flight including 254, 280 and 300 nm UV light, full light and total darkness of space. Phenotypic isolates were grown on human hair collected from one source at years 1 and 23 after splashdown. The patterns of fungal growth on the hair, and the hair deterioration rates, were noted according to the space exposure. Growth and deterioration were consistent but slightly reduced at year 23. PMID:7476563
NASA Astrophysics Data System (ADS)
Li, Xiaozhou; Yang, Tianyue; Li, Siqi; Yao, Jun; Song, Youtao; Wang, Deli; Ding, Jianhua
2015-11-01
Surface enhanced Raman spectroscopy (SERS) has been recognized as an effective tool for the analysis of tissue samples and biofluids. In this work, a total of 27 spectral parameters were chosen and compared using SERS. Four parameters with the highest prediction ability were selected for further support vector machine (SVM) analysis. As a comparison, principal component analysis (PCA) was used on the same dataset for feature extraction. SVM was used with the above two data reduction methods separately to differentiate colon cancer and the control groups. Serum taken from 52 colon cancer patients and 60 healthy volunteers were collected and tested by SERS. The accuracy for Parameter-SVM was 95.0%, the sensitivity was 96.2%, and the specificity was 95.5%, which was much higher than the results using only one parameter, while for PCA-SVM, the results are 93.3%, 92.3%, and 92.9%, respectively. These results demonstrate that the SERS analysis method can be used to identify serum differences between colon cancer patients and normal people.
NASA Astrophysics Data System (ADS)
Frisch, H.
2010-11-01
Context. The linear polarization of a strong resonance lines observed near the solar limb is created by a multiple-scattering process. Partial frequency redistribution (PRD) effects must be accounted for to explain the polarization profiles. The redistribution matrix describing the scattering process is a sum of terms, each containing a PRD function multiplied by a Rayleigh type phase matrix. A standard approximation made in calculating the polarization is to average the PRD functions over all the scattering angles, because the numerical work needed to take the angle-dependence of the PRD functions into account is large and not always needed for reasonable evaluations of the polarization. Aims: This paper describes a Stokes parameters decomposition method, that is applicable in plane-parallel cylindrically symmetrical media, which aims at simplifying the numerical work needed to overcome the angle-average approximation. Methods: The decomposition method relies on an azimuthal Fourier expansion of the PRD functions associated to a decomposition of the phase matrices in terms of the Landi Degl'Innocenti irreducible spherical tensors for polarimetry T^K_Q(i, Ω) (i Stokes parameter index, Ω ray direction). The terms that depend on the azimuth of the scattering angle are retained in the phase matrices. Results: It is shown that the Stokes parameters I and Q, which have the same cylindrical symmetry as the medium, can be expressed in terms of four cylindrically symmetrical components I_Q^K (K = Q = 0, K = 2, Q = 0, 1, 2). The components with Q = 1, 2 are created by the angular dependence of the PRD functions. They go to zero at disk center, ensuring that Stokes Q also goes to zero. Each component I_Q^K is a solution to a standard radiative transfer equation. The source term S_Q^K are significantly simpler than the source terms corresponding to I and Q. They satisfy a set of integral equations that can be solved by an accelerated lambda iteration (ALI) method.
Mellado, J M; Calmet, J; Olona, M; Giné, J; Saurí, A
2004-05-01
We evaluated the diagnostic utility of magnetic resonance imaging (MRI) for predicting anterior cruciate ligament (ACL) tears using both quantitative parameters and nonquantitative imaging findings. MRI examinations were retrospectively evaluated in a group of patients with arthroscopically confirmed complete ACL tear and in a control group with arthroscopically confirmed intact ACL. We evaluated multiple MRI features to compare their sensitivity and specificity for detecting ACL tears. Particular emphasis is put on the evaluation of three different quantitative parameters, including a simplified method for measuring the ACL angle. With a threshold value of 45 degrees the ACL angle reached a sensitivity and specificity of 100% for detecting ACL tears. With a threshold value of 0 degrees the Blumensaat angle had a sensitivity of 90% and a specificity of 98%. Finally, a threshold value of 115 degrees gave the posterior cruciate ligament angle a sensitivity of 70% and a specificity of 82%. Discontinuity was found to be the most useful of the ACL abnormalities. Of the secondary findings anterior tibial displacement was the best predictor of ligamentous injury. However, ACL abnormalities and secondary findings, alone or combined, failed to surpass the diagnostic value of the ACL angle for predicting ACL tears. Quantitative parameters are thus good predictors of ACL tears and may increase the overall sensitivity and specificity of MRI. The ACL angle may be confidently measured in a single MRI section and can be considered to be the most reliable quantitative parameter for detecting ACL tears. PMID:14530852
NASA Technical Reports Server (NTRS)
Baxa, Ernest G., Jr.; Lee, Jonggil
1991-01-01
The pulse pair method for spectrum parameter estimation is commonly used in pulse Doppler weather radar signal processing since it is economical to implement and can be shown to be a maximum likelihood estimator. With the use of airborne weather radar for windshear detection, the turbulent weather and strong ground clutter return spectrum differs from that assumed in its derivation, so the performance robustness of the pulse pair technique must be understood. Here, the effect of radar system pulse to pulse phase jitter and signal spectrum skew on the pulse pair algorithm performance is discussed. Phase jitter effect may be significant when the weather return signal to clutter ratio is very low and clutter rejection filtering is attempted. The analysis can be used to develop design specifications for airborne radar system phase stability. It is also shown that the weather return spectrum skew can cause a significant bias in the pulse pair mean windspeed estimates, and that the poly pulse pair algorithm can reduce this bias. It is suggested that use of a spectrum mode estimator may be more appropriate in characterizing the windspeed within a radar range resolution cell for detection of hazardous windspeed gradients.
Skrypnyk, T. E-mail: tskrypnyk@imath.kiev.ua
2015-02-15
Using the technique of classical r-matrices and quantum Lax operators, we construct the most general form of the quantum integrable “n-level, many-mode” spin-boson Jaynes-Cummings-Dicke-type hamiltonians describing an interaction of a molecule of N n-level atoms with many modes of electromagnetic field and containing, in general, additional non-linear interaction terms. We explicitly obtain the corresponding quantum Lax operators and spin-boson analogs of the generalized Gaudin hamiltonians and prove their quantum commutativity. We investigate symmetries of the obtained models that are associated with the geometric symmetries of the classical r-matrices and construct the corresponding algebra of quantum integrals. We consider in detail three classes of non-skew-symmetric classical r-matrices with spectral parameters and explicitly obtain the corresponding quantum Lax operators and Jaynes-Cummings-Dicke-type hamiltonians depending on the considered r-matrix.
Submillimeter, millimeter, and microwave spectral line catalogue
NASA Technical Reports Server (NTRS)
Poynter, R. L.; Pickett, H. M.
1980-01-01
A computer accessible catalogue of submillimeter, millimeter, and microwave spectral lines in the frequency range between O and 3000 GHz (such as; wavelengths longer than 100 m) is discussed. The catalogue was used as a planning guide and as an aid in the identification and analysis of observed spectral lines. The information listed for each spectral line includes the frequency and its estimated error, the intensity, lower state energy, and quantum number assignment. The catalogue was constructed by using theoretical least squares fits of published spectral lines to accepted molecular models. The associated predictions and their estimated errors are based upon the resultant fitted parameters and their covariances.
NASA Technical Reports Server (NTRS)
Howell, L. W.
2001-01-01
A simple power law model consisting of a single spectral index alpha-1 is believed to be an adequate description of the galactic cosmic-ray (GCR) proton flux at energies below 10(exp 13) eV. Two procedures for estimating alpha-1 the method of moments and maximum likelihood (ML), are developed and their statistical performance compared. It is concluded that the ML procedure attains the most desirable statistical properties and is hence the recommended statistical estimation procedure for estimating alpha-1. The ML procedure is then generalized for application to a set of real cosmic-ray data and thereby makes this approach applicable to existing cosmic-ray data sets. Several other important results, such as the relationship between collecting power and detector energy resolution, as well as inclusion of a non-Gaussian detector response function, are presented. These results have many practical benefits in the design phase of a cosmic-ray detector as they permit instrument developers to make important trade studies in design parameters as a function of one of the science objectives. This is particularly important for space-based detectors where physical parameters, such as dimension and weight, impose rigorous practical limits to the design envelope.
NASA Astrophysics Data System (ADS)
Kordy, M.; Wannamaker, P.; Maris, V.; Cherkaev, E.; Hill, G.
2016-01-01
We have developed an algorithm, which we call HexMT, for 3-D simulation and inversion of magnetotelluric (MT) responses using deformable hexahedral finite elements that permit incorporation of topography. Direct solvers parallelized on symmetric multiprocessor (SMP), single-chassis workstations with large RAM are used throughout, including the forward solution, parameter Jacobians and model parameter update. In Part I, the forward simulator and Jacobian calculations are presented. We use first-order edge elements to represent the secondary electric field (E), yielding accuracy O(h) for E and its curl (magnetic field). For very low frequencies or small material admittivities, the E-field requires divergence correction. With the help of Hodge decomposition, the correction may be applied in one step after the forward solution is calculated. This allows accurate E-field solutions in dielectric air. The system matrix factorization and source vector solutions are computed using the MKL PARDISO library, which shows good scalability through 24 processor cores. The factorized matrix is used to calculate the forward response as well as the Jacobians of electromagnetic (EM) field and MT responses using the reciprocity theorem. Comparison with other codes demonstrates accuracy of our forward calculations. We consider a popular conductive/resistive double brick structure, several synthetic topographic models and the natural topography of Mount Erebus in Antarctica. In particular, the ability of finite elements to represent smooth topographic slopes permits accurate simulation of refraction of EM waves normal to the slopes at high frequencies. Run-time tests of the parallelized algorithm indicate that for meshes as large as 176 × 176 × 70 elements, MT forward responses and Jacobians can be calculated in ˜1.5 hr per frequency. Together with an efficient inversion parameter step described in Part II, MT inversion problems of 200-300 stations are computable with total run times
NASA Astrophysics Data System (ADS)
Moussa, Hesham Hussein Mohamed
2008-10-01
Teleseismic Broadband seismograms of P-waves from the May 1990 southern Sudan and the December, 2005 Lake Tanganyika earthquakes; the western branch of the East African Rift System at different azimuths have been investigated on the basis of magnitude spectra. The two earthquakes are the largest shocks in the East African Rift System and its extension in southern Sudan. Focal mechanism solutions along with geological evidences suggest that the first event represents a complex style of the deformation at the intersection of the northern branch of the western branch of the East African Rift and Aswa Shear Zone while the second one represents the current tensional stress on the East African Rift. The maximum average spectral magnitude for the first event is determined to be 6.79 at 4 s period compared to 6.33 at 4 s period for the second event. The other source parameters for the two earthquakes were also estimated. The first event had a seismic moment over fourth that of the second one. The two events are radiated from patches of faults having radii of 13.05 and 7.85 km, respectively. The average displacement and stress drop are estimated to be 0.56 m and 1.65 MPa for the first event and 0.43 m and 2.20 MPa for the second one. The source parameters that describe inhomogeneity of the fault are also determined from the magnitude spectra. These additional parameters are complexity, asperity radius, displacements across the asperity and ambient stress drop. Both events produce moderate rupture complexity. Compared to the second event, the first event is characterized by relatively higher complexity, a low average stress drop and a high ambient stress. A reasonable explanation for the variations in these parameters may suggest variation in the strength of the seismogenic fault which provides the relations between the different source parameters. The values of stress drops and the ambient stresses estimated for both events indicate that these earthquakes are of interplate
Chen, Han; Danielsson, Mats; Xu, Cheng
2016-06-01
We are developing a photon-counting spectral CT detector with a small pixel size of [Formula: see text] mm(2), offering a potential advantage for better visualization of small structures in pediatric patients. The purpose of this study is to determine the patient size dependent scanning parameters (kVp and mAs) for pediatric CT in two imaging cases: adipose imaging and iodinated blood imaging. Cylindrical soft-tissue phantoms of diameters between 10-25 cm were used to mimic patients of different ages from 0 to 15 y. For adipose imaging, a 5 mm diameter adipose sphere was assumed as an imaging target, while in the case of iodinated imaging, an iodinated blood sphere of 1 mm in diameter was assumed. By applying the geometry of a commercial CT scanner (GE Lightspeed VCT), simulations were carried out to calculate the detectability index, [Formula: see text], with tube potentials varying from 40 to 140 kVp. The optimal kVp for each phantom in each imaging case was determined such that the dose-normalized detectability index, [Formula: see text]dose, is maximized. With the assumption that the detectability index in pediatric imaging is required the same as in typical adult imaging, the value of mAs at optimal kVp for each phantom was selected to achieve a reference detectability index that was obtained by scanning an adult phantom (30 cm in diameter) in a typical adult CT procedure (120 kVp and 200 mAs) using a modeled energy-integrating system. For adipose imaging, the optimal kVps are 50, 60, 80, and 120 kVp, respectively, for phantoms of 10, 15, 20, and 25 cm in diameter. The corresponding mAs values required to achieve the reference detectability index are only 9%, 23%, 24%, and 54% of the mAs that is used for adult patients at 120 kVp, for 10, 15, 20, and 25 cm diameter phantoms, respectively. In the case of iodinated imaging, a tube potential of 60 kVp was found optimal for all phantoms investigated, and the mAs values required to achieve the reference
NASA Astrophysics Data System (ADS)
Chen, Han; Danielsson, Mats; Xu, Cheng
2016-06-01
We are developing a photon-counting spectral CT detector with a small pixel size of 0.4× 0.5 mm2, offering a potential advantage for better visualization of small structures in pediatric patients. The purpose of this study is to determine the patient size dependent scanning parameters (kVp and mAs) for pediatric CT in two imaging cases: adipose imaging and iodinated blood imaging. Cylindrical soft-tissue phantoms of diameters between 10–25 cm were used to mimic patients of different ages from 0 to 15 y. For adipose imaging, a 5 mm diameter adipose sphere was assumed as an imaging target, while in the case of iodinated imaging, an iodinated blood sphere of 1 mm in diameter was assumed. By applying the geometry of a commercial CT scanner (GE Lightspeed VCT), simulations were carried out to calculate the detectability index, {{d}\\prime 2} , with tube potentials varying from 40 to 140 kVp. The optimal kVp for each phantom in each imaging case was determined such that the dose-normalized detectability index, {{d}\\prime 2}/ dose, is maximized. With the assumption that the detectability index in pediatric imaging is required the same as in typical adult imaging, the value of mAs at optimal kVp for each phantom was selected to achieve a reference detectability index that was obtained by scanning an adult phantom (30 cm in diameter) in a typical adult CT procedure (120 kVp and 200 mAs) using a modeled energy-integrating system. For adipose imaging, the optimal kVps are 50, 60, 80, and 120 kVp, respectively, for phantoms of 10, 15, 20, and 25 cm in diameter. The corresponding mAs values required to achieve the reference detectability index are only 9%, 23%, 24%, and 54% of the mAs that is used for adult patients at 120 kVp, for 10, 15, 20, and 25 cm diameter phantoms, respectively. In the case of iodinated imaging, a tube potential of 60 kVp was found optimal for all phantoms investigated, and the mAs values required to achieve the reference detectability
NASA Astrophysics Data System (ADS)
Remsberg, Ellis; Burton, John; Gordley, Larry; Marshall, Benjamin T.; Bhatt, Praful; Miles, Thomas
1995-08-01
Ozone distributions from the Nimbus 7 Limb Infrared Monitor of the Stratosphere (LIMS) experiment of 1978-1979 are generally in good agreement with other concurrent ozone measurements in the middle and upper stratosphere, but not at lower altitudes. LIMS ozone is too large below about the 15-hPa (or millibar) level, particularly at lower latitudes. A new LIMS ozone distribution is presented for 1 day of profiles, May 5, 1979, obtained with an improved forward radiance algorithm and using the spectral line parameters for the 9- to 10-μm region in the HITRAN 92 compilation. However, we also divided our single day of retrieved ozone mixing ratio profiles by a suggested factor of 1.051, which makes them compatible with the ozone distributions from several of the UARS experiments. Our revised distribution still agrees with the archived LIMS ozone to better than ±5% above about the 15-hPa level, but there is a significant decrease for the revised ozone in the lower stratosphere. That decrease approaches 25% at 50 hPa in the tropics. In general, the revised LIMS ozone is now in accord with the comparison data sets for the stratosphere, except for the lowest levels (Umkehr layer 3 or 63-127 hPa), where the effects of interfering species and small biases in LIMS temperatures are most pronounced. It is concluded that the current 9- to 10-μm ozone line list is adequate for obtaining good quality ozone mixing ratio profiles from satellite broadband limb-infrared measurements.
Chemyakin, Eduard; Müller, Detlef; Burton, Sharon; Kolgotin, Alexei; Hostetler, Chris; Ferrare, Richard
2014-11-01
We present the results of a feasibility study in which a simple, automated, and unsupervised algorithm, which we call the arrange and average algorithm, is used to infer microphysical parameters (complex refractive index, effective radius, total number, surface area, and volume concentrations) of atmospheric aerosol particles. The algorithm uses backscatter coefficients at 355, 532, and 1064 nm and extinction coefficients at 355 and 532 nm as input information. Testing of the algorithm is based on synthetic optical data that are computed from prescribed monomodal particle size distributions and complex refractive indices that describe spherical, primarily fine mode pollution particles. We tested the performance of the algorithm for the "3 backscatter (β)+2 extinction (α)" configuration of a multiwavelength aerosol high-spectral-resolution lidar (HSRL) or Raman lidar. We investigated the degree to which the microphysical results retrieved by this algorithm depends on the number of input backscatter and extinction coefficients. For example, we tested "3β+1α," "2β+1α," and "3β" lidar configurations. This arrange and average algorithm can be used in two ways. First, it can be applied for quick data processing of experimental data acquired with lidar. Fast automated retrievals of microphysical particle properties are needed in view of the enormous amount of data that can be acquired by the NASA Langley Research Center's airborne "3β+2α" High-Spectral-Resolution Lidar (HSRL-2). It would prove useful for the growing number of ground-based multiwavelength lidar networks, and it would provide an option for analyzing the vast amount of optical data acquired with a future spaceborne multiwavelength lidar. The second potential application is to improve the microphysical particle characterization with our existing inversion algorithm that uses Tikhonov's inversion with regularization. This advanced algorithm has recently undergone development to allow automated and
NASA Astrophysics Data System (ADS)
Toumi, S.; Ouennoughi, Z.; Strenger, K. C.; Frey, L.
2016-08-01
Current conduction mechanisms through a Metal-Oxide-Semiconductor structure are characterized via Fowler-Nordheim (FN) plots. The extraction of the FN parameters like the electron/hole effective mass in oxide mox and in semiconductor msc, the barrier height at the semiconductor-oxide interface ϕB, and the correction oxide voltage Vcorr for a MOS structure is made using a vertical optimization process on the current density without any assumption about ϕB or mox. An excellent agreement is obtained between the FN plots calculated with the FN parameters extracted using a vertical optimization process with the experimental one.
NASA Astrophysics Data System (ADS)
Hendricks Franssen, H. J.; Kaiser, H. P.; Kuhlmann, U.; Bauser, G.; Stauffer, F.; Müller, R.; Kinzelbach, W.
2011-02-01
Urban groundwater is frequently contaminated, and the exact location of the pollution spots is often unknown. Intelligent monitoring of the temporal variations in groundwater flow in such an area assists in selectively extracting groundwater of drinking water quality. Here an example from the city of Zurich (Switzerland) is shown. The monitoring strategy consists of using the ensemble Kalman filter (EnKF) for optimally combining online observations and online models for the real-time characterization of groundwater flow. We conducted numerical simulation experiments for the period January 2004 to December 2007 with a 3-D finite element model for variably saturated groundwater flow. It was found that the daily assimilation of piezometric head data with EnKF results in a better characterization of piezometric heads than does a model which is inversely calibrated with historical data but not updated in real time. The positive impact of model updating with observations can still be observed 10 days after the update. These simulations also suggest that parameters (hydraulic conductivity and leakage) are successfully updated: 1 and 10 day piezometric head predictions are better with than without updating of parameters. Additional experiments with a synthetic model for the same site, in which the only difference is that certain parameter values are selected as the unknown "true" conditions, show that EnKF also successfully updates unknown parameters. However, this is only the case if spatially distributed hydraulic conductivities and leakage coefficients are jointly updated and if a damping parameter is used. The mean absolute error of estimated log leakage coefficients decreased by up to 63%; for log hydraulic conductivity a decrease of up to 27% was observed. From January 2009 the method has been operational at the Water Works Zurich and showed a remarkable performance until present (October 2010).
NASA Technical Reports Server (NTRS)
Pinter, P. J.; Jackson, R. D.; Idso, S. B.; Reginato, R. J. (Principal Investigator)
1982-01-01
Spectral reflectances of Produra wheat were measured at 13 different times of the day at Phoenix, Arizona, during April 1979 using a nadir-oriented hand-held 4-band radiometer which had bandpass characteristics similar to those on LANDSAT satellites. Different Sun altitude and azimuth angles caused significant diurnal changes in radiant return in both visible and near-IR regions of the spectrum and in several vegetation indices derived from them. The magnitude of these changes were related to different canopy architecture, percent cover and green leaf area conditions. Spectral measurements taken at each time period were well correlated with green leaf area index but the nature of the relationship changed significantly with time of day. Thus, a significant bias in the estimation of the green leaf area index from remotely sensed spectral data could occur if sun angles are not properly accounted for.
NASA Technical Reports Server (NTRS)
Butera, M. K.; Frick, A.
1984-01-01
Aircraft simulated thematic mapper data and field data were acquired in the fall and spring to analyze the relationship of spectral response and biomass for the marsh grass Spartina patens. Regression results indicate no simple relationship exists for TMS spectral response and biomass with a high R sq. However, results show a consistent relationship between spectral response and the percent live vegetation (by weight) and percent interstitial standing surface water (by area) as independent variables. It is suggested that the reflected energy of a pixel represents a mixture of surface constituents. It is recommended that alternative remote sensors be employed to account for the pixel constituents of live and dead vegetation, litter, and standing water.
NASA Astrophysics Data System (ADS)
Marjani, Saeid; Hosseini, Seyed Ebrahim
2015-09-01
This paper presents a radio-frequency (RF) small-signal model for the hetero-gate-dielectric p-n-p-n tunnel field-effect transistor (HG p-n-p-n TFET) that includes the charge conservation capacitance and the substrate parameters. The HG p-n-p-n TFET is evaluated in terms of various RF parameters, including the cut-off frequency, the maximum oscillation frequency, capacitances, resistances, conductances, and transport time delay. The extracted small-signal parameters and RF performance values are compared with those of the low-κ p-n-p-n TFET. A nonquasistatic RF small-signal model has been used along with SPICE simulations and small-signal parameters that were extracted from the simulated device Y-parameters to simulate the HG p-n-p-n TFET. It is confirmed using the Y-parameters and the extracted parameters that this model with the extracted charge conservation capacitance and substrate parameters is valid in the high frequency range up to 100 GHz. In addition, it is shown that a significant circuit performance error may be introduced if the charge conservation capacitance and the substrate parameters are not considered appropriately.
NASA Astrophysics Data System (ADS)
Triaud, A. H. M. J.; Hebb, L.; Anderson, D. R.; Cargile, P.; Collier Cameron, A.; Doyle, A. P.; Faedi, F.; Gillon, M.; Gomez Maqueo Chew, Y.; Hellier, C.; Jehin, E.; Maxted, P.; Naef, D.; Pepe, F.; Pollacco, D.; Queloz, D.; Ségransan, D.; Smalley, B.; Stassun, K.; Udry, S.; West, R. G.
2013-01-01
This paper introduces a series of papers aiming to study the dozens of low-mass eclipsing binaries (EBLM), with F, G, K primaries, that have been discovered in the course of the WASP survey. Our objects are mostly single-line binaries whose eclipses have been detected by WASP and were initially followed up as potential planetary transit candidates. These have bright primaries, which facilitates spectroscopic observations during transit and allows the study of the spin-orbit distribution of F, G, K+M eclipsing binaries through the Rossiter-McLaughlin effect. Here we report on the spin-orbit angle of WASP-30b, a transiting brown dwarf, and improve its orbital parameters. We also present the mass, radius, spin-orbit angle and orbital parameters of a new eclipsing binary, J1219-39b (1SWAPJ121921.03-395125.6, TYC 7760-484-1), which, with a mass of 95 ± 2 Mjup, is close to the limit between brown dwarfs and stars. We find that both objects have projected spin-orbit angles aligned with their primaries' rotation. Neither primaries are synchronous. J1219-39b has a modestly eccentric orbit and is in agreement with the theoretical mass-radius relationship, whereas WASP-30b lies above it. Using WASP-South photometric observations (Sutherland, South Africa) confirmed with radial velocity measurement from the CORALIE spectrograph, photometry from the EulerCam camera (both mounted on the Swiss 1.2 m Euler Telescope), radial velocities from the HARPS spectrograph on the ESO's 3.6 m Telescope (prog ID 085.C-0393), and photometry from the robotic 60 cm TRAPPIST telescope, all located at ESO, La Silla, Chile. The data is publicly available at the CDS Strasbourg and on demand to the main author.Tables A.1-A.3 are available in electronic form at http://www.aanda.orgPhotometry tables are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/549/A18
Chaudhry, S.R.; Ahmed-Zaid, S.; Demerdash, N.A.
1995-03-01
In this paper, a coupled finite-element/state-space modeling technique is applied in the determination of the steady-state parameters of a 733-MVA turbogenerator in the abc frame of reference. In this modeling environment, the forward rotor stepping-finite element procedure described in a companion paper is used to obtain the various machine self and mutual inductances under short-circuit and load conditions. A fourth-order state-space model of the armature and field winding flux linkages in the ABC frame of reference is then used to obtain the next set of flux linkages and forcing function currents for the finite-element model. In this process, one iterates between the finite-element and state-space techniques until the terminal conditions converge to specified values. This method is applied to the determination of the short-circuit, and reduced and rated-voltage load characteristics, and the corresponding machine inductances. The spatial harmonics of these inductances are analyzed via Fourier analysis to reveal the impact of machine geometry and stator-to-rotor relative motion, winding layout, magnetic saturation, and other effects. In the full-load infinite-bus case, it is found that, while the three-phase terminal voltages are pure sinusoidal waveforms, the steady-state armature phase currents are non-sinusoidal and contain a substantial amount of odd harmonics which cannot be obtained using the traditional two-axis analysis.
Sandala, Gregory M.; Hopmann, Kathrin H.; Ghosh, Abhik
2011-01-01
Six popular density functionals in conjunction with the conductor-like screening (COSMO) solvation model have been used to obtain linear Mössbauer isomer shift (IS) and quadrupole splitting (QS) parameters for a test set of 20 complexes (with 24 sites) comprised of nonheme nitrosyls (Fe–NO) and non-nitrosyl (Fe–S) complexes. For the first time in an IS analysis, the Fe electron density was calculated both directly at the nucleus, ρ(0)N, which is the typical procedure, and on a small sphere surrounding the nucleus, ρ(0)S, which is the new standard algorithm implemented in the ADF software package. We find that both methods yield (near) identical slopes from each linear regression analysis but are shifted with respect to ρ(0) along the x-axis. Therefore, the calculation of the Fe electron density with either method gives calibration fits with equal predictive value. Calibration parameters obtained from the complete test set for OLYP, OPBE, PW91, and BP86 yield correlation coefficients (r2) of approximately 0.90, indicating that the calibration fit is of good quality. However, fits obtained from B3LYP and B3LYP* with both Slater-type and Gaussian-type orbitals are generally found to be of poorer quality. For several of the complexes examined in this study, we find that B3LYP and B3LYP* give geometries that possess significantly larger deviations from the experimental structures than OLYP, OPBE, PW91 or BP86. This phenomenon is particularly true for the di- and tetranuclear Fe complexes examined in this study. Previous Mössbauer calibration fit studies using these functionals have usually included mononuclear Fe complexes alone, where these discrepancies are less pronounced. An examination of spin expectation values reveals B3LYP and B3LYP* approach the weak-coupling limit more closely than the GGA exchange-correlation functionals. The high degree of variability in our calculated S2 values for the Fe–NO complexes highlights their challenging electronic
NASA Astrophysics Data System (ADS)
Pawlak, M.; Chirtoc, M.; Horny, N.; Pelzl, J.
2016-03-01
Spectrally resolved modulated infrared radiometry (SR-MIRR) with super-band gap photoexcitation is introduced as a self-consistent method for semiconductor characterization (CdSe crystals grown under different conditions). Starting from a theoretical model combining the contributions of the photothermal (PT) and photocarrier (PC) signal components, an expression is derived for the thermal-to-plasma wave transition frequency ftc which is found to be wavelength-independent. The deviation of the PC component from the model at high frequency is quantitatively explained by a quasi-continuous distribution of carrier recombination lifetimes. The integral, broad frequency band (0.1 Hz-1 MHz) MIRR measurements simultaneously yielded the thermal diffusivity a, the effective IR optical absorption coefficient βeff, and the bulk carrier lifetime τc. Spectrally resolved frequency scans were conducted with interchangeable IR bandpass filters (2.2-11.3 μm) in front of the detector. The perfect spectral match of the PT and PC components is the direct experimental evidence of the key assumption in MIRR that de-exciting carriers are equivalent to blackbody (Planck) radiators. The exploitation of the β spectrum measured by MIRR allowed determining the background (equilibrium) free carrier concentration n0. At the shortest wavelength (3.3 μm), the photoluminescence (PL) component supersedes the PC one and has distinct features. The average sample temperature influences the PC component but not the PT one.
NASA Astrophysics Data System (ADS)
Li, Yun-He; Zhang, Jing-Fei; Zhang, Xin
2014-12-01
Dark energy can modify the dynamics of dark matter if there exists a direct interaction between them. Thus, a measurement of the structure growth, e.g., redshift-space distortions (RSDs), can provide a powerful tool to constrain the interacting dark energy (IDE) models. For the widely studied Q =3 β H ρde model, previous works showed that only a very small coupling [β ˜O (10-3) ] can survive in current RSD data. However, all of these analyses had to assume w >-1 and β >0 due to the existence of the large-scale instability in the IDE scenario. In our recent work [Phys. Rev. D 90, 063005 (2014)], we successfully solved this large-scale instability problem by establishing a parametrized post-Friedmann framework for the IDE scenario. So we, for the first time, have the ability to explore the full parameter space of the IDE models. In this work, we re-examine the observational constraints on the Q =3 β H ρde model within the parametrized post-Friedmann framework. By using the Planck data, the baryon acoustic oscillation data, the JLA sample of supernovae, and the Hubble constant measurement, we get β =-0.01 0-0.033+0.037 (1 σ ). The fit result becomes β =-0.014 8-0.0089+0.0100 (1 σ ) once we further incorporate the RSD data in the analysis. The error of β is substantially reduced with the help of the RSD data. Compared with the previous results, our results show that a negative β is favored by current observations, and a relatively larger interaction rate is permitted by current RSD data.
Submillimeter, millimeter, and microwave spectral line catalogue
NASA Technical Reports Server (NTRS)
Poynter, R. L.; Pickett, H. M.
1981-01-01
A computer accessible catalogue of submillimeter, millimeter and microwave spectral lines in the frequency range between 0 and 3000 GHZ (i.e., wavelengths longer than 100 mu m) is presented which can be used a planning guide or as an aid in the identification and analysis of observed spectral lines. The information listed for each spectral line includes the frequency and its estimated error, the intensity, lower state energy, and quantum number assignment. The catalogue was constructed by using theoretical least squares fits of published spectral lines to accepted molecular models. The associated predictions and their estimated errors are based upon the resultant fitted parameters and their covariances. Future versions of this catalogue will add more atoms and molecules and update the present listings (133 species) as new data appear. The catalogue is available as a magnetic tape recorded in card images and as a set of microfiche records.
Submillimeter, millimeter, and microwave spectral line catalogue
NASA Technical Reports Server (NTRS)
Poynter, R. L.; Pickett, H. M.
1984-01-01
This report describes a computer accessible catalogue of submillimeter, millimeter, and microwave spectral lines in the frequency range between 0 and 10000 GHz (i.e., wavelengths longer than 30 micrometers). The catalogue can be used as a planning guide or as an aid in the identification and analysis of observed spectral lines. The information listed for each spectral line includes the frequency and its estimated error, the intensity, lower state energy, and quantum number assignment. The catalogue has been constructed using theoretical least squares fits of published spectral lines to accepted molecular models. The associated predictions and their estimated errors are based upon the resultant fitted parameters and their covariances. Future versions of this catalogue will add more atoms and molecules and update the present listings (151 species) as new data appear. The catalogue is available from the authors as a magnetic tape recorded in card images and as a set of microfiche records.
NASA Astrophysics Data System (ADS)
Ara Hussain, Amreen; Ratan Pal, Arup; Bailung, Heremba; Chutia, Joyanti; Patil, Dinkar S.
2013-08-01
Polyaniline based composites incorporating titanium dioxide have been synthesized by an alternative pathway using reactive magnetron sputtering of titanium and plasma polymerization of aniline monomer. Structural, optical and morphological characterizations of plasma polymerized aniline (PPani) and titanium dioxide (TiO2) composites (PPani-TiO2) reveal the evidence for the incorporation of TiO2 in the PPani matrix. A hybrid heterostructure device having PPani-TiO2 composite with a top gold (Au) layer and bottom indium-tin oxide (ITO) layer is fabricated. The developed heterostructure device exhibits rectifying behaviour indicating the formation of a Schottky contact between Au and PPani-TiO2. The detailed electrical measurement of the device is performed under different temperatures. The ideality factor (n) and barrier height (φB) of the heterojunction diode at room temperature (300 K) are found to be 1.28 and 0.43 eV, respectively. Possible conduction mechanisms are examined using various plotting and curve fitting methods for space charge limited conduction mechanism (SCLC), Schottky emission mechanism and Poole-Frenkel (PF) emission mechanism. The heterostructure device shows best fit of SCLC process as compared to the other mechanisms including Schottky emission and PF emission.
Abboud, F; Scalliet, P; Vynckier, S
2008-12-01
Permanent implantation of 125I (iodine) or 103Pd (palladium) sources is a popular treatment option in the management of early stage prostate cancer. New sources are being developed, some of which are being marketed for different clinical applications. A new technique of adjuvant stereotactic permanent seed breast implant, similar to that used in the treatment of prostate cancer, has been proposed by [N. Jansen et al., Int. J. Radiat. Oncol. Biol. Phys. 67, 1052-1058 (2007)] with encouraging results. The presence of artifacts from the metallic seeds, however, can disturb follow-up imaging. The development of plastic seeds has reduced these artifacts. This paper presents a feasibility study of the advantages of palladium-103 seeds, encapsulated with a biocompatible polymer, for future clinical applications, and on the effect of the gold marker on the dosimetric characteristics of such seeds. Experimental palladium seeds, OptiSeedexp, were manufactured by International Brachytherapy (IBt), Seneffe, Belgium, from a biocompatible polymer, including the marker. Apart from the absence of a gold marker, the studied seed has an identical design to the OptiSeed103 [Phys. Med. Biol. 50, 1493-1504 (2005)]; [Appl. Radiat. Isot. 63, 311-321 (2005)]. Polymer encapsulation was preferred by IBt in order to reduce the quantity of radioactive material needed for a given dose rate and to reduce the anisotropy of the radiation field around the seed. In addition, this design is intended to decrease the interseed effects that can occur as a result of the marker and the encapsulation. Dosimetric measurements were performed using LiF thermoluminescent dosimeters (1 mm3) in solid water phantoms (WT1). Measured data were compared to Monte Carlo simulated data in solid water using the MCNP code, version 4C. Updated cross sections [Med. Phys. 30, 701-711 (2003)] were used. As the measured and calculated data were in agreement, Monte Carlo calculations were then performed in liquid water to
Abboud, F.; Scalliet, P.; Vynckier, S.
2008-12-15
Permanent implantation of {sup 125}I (iodine) or {sup 103}Pd (palladium) sources is a popular treatment option in the management of early stage prostate cancer. New sources are being developed, some of which are being marketed for different clinical applications. A new technique of adjuvant stereotactic permanent seed breast implant, similar to that used in the treatment of prostate cancer, has been proposed by [N. Jansen et al., Int. J. Radiat. Oncol. Biol. Phys. 67, 1052-1058 (2007)] with encouraging results. The presence of artifacts from the metallic seeds, however, can disturb follow-up imaging. The development of plastic seeds has reduced these artifacts. This paper presents a feasibility study of the advantages of palladium-103 seeds, encapsulated with a biocompatible polymer, for future clinical applications, and on the effect of the gold marker on the dosimetric characteristics of such seeds. Experimental palladium seeds, OptiSeed{sup exp}, were manufactured by International Brachytherapy (IBt), Seneffe, Belgium, from a biocompatible polymer, including the marker. Apart from the absence of a gold marker, the studied seed has an identical design to the OptiSeed{sup 103}[Phys. Med. Biol. 50, 1493-1504 (2005)]; [Appl. Radiat. Isot. 63, 311-321 (2005)]. Polymer encapsulation was preferred by IBt in order to reduce the quantity of radioactive material needed for a given dose rate and to reduce the anisotropy of the radiation field around the seed. In addition, this design is intended to decrease the interseed effects that can occur as a result of the marker and the encapsulation. Dosimetric measurements were performed using LiF thermoluminescent dosimeters (1 mm{sup 3}) in solid water phantoms (WT1). Measured data were compared to Monte Carlo simulated data in solid water using the MCNP code, version 4C. Updated cross sections [Med. Phys. 30, 701-711 (2003)] were used. As the measured and calculated data were in agreement, Monte Carlo calculations were then
Spectral and Spread Spectral Teleportation
Humble, Travis S
2010-01-01
We report how quantum information encoded into the spectral degree of freedom of a single-photon state is teleported using a finite spectrally entangled biphoton state. We further demonstrate how the bandwidth of a teleported waveform can be controllably and coherently dilated using a spread spectral variant of teleportation. We present analytical fidelities for spectral and spread spectral teleportation when complex-valued Gaussian states are prepared using a proposed experimental approach, and we discuss the utility of these techniques for integrating broad-bandwidth photonic qubits with narrow-bandwidth receivers in quantum communication systems.
A Statistical and Spectral Model for Representing Noisy Sounds with Short-Time Sinusoids
NASA Astrophysics Data System (ADS)
Hanna, Pierre; Desainte-Catherine, Myriam
2005-12-01
We propose an original model for noise analysis, transformation, and synthesis: the CNSS model. Noisy sounds are represented with short-time sinusoids whose frequencies and phases are random variables. This spectral and statistical model represents information about the spectral density of frequencies. This perceptually relevant property is modeled by three mathematical parameters that define the distribution of the frequencies. This model also represents the spectral envelope. The mathematical parameters are defined and the analysis algorithms to extract these parameters from sounds are introduced. Then algorithms for generating sounds from the parameters of the model are presented. Applications of this model include tools for composers, psychoacoustic experiments, and pedagogy.
Hu, Nvdan; Gong, Yulong; Wang, Xinchao; Lu, Yao; Peng, Guangyue; Yang, Long; Zhang, Shengtao; Luo, Ziping; Li, Hongru; Gao, Fang
2015-11-01
A series of new asymmetric chromophores containing aromatic substituents and possessing the excellent π-extension in space were prepared through multi-steps routes. One-photon and two-photon spectral properties of these new chromophores could be tuned by these substituents finely and simultaneously. The linear correlation of the wave numbers of the one-photon absorption and emission maxima to Hammett parameters of these substituents was presented. Near infrared two-photon absorption emission integrated areas of the target chromophores were correlated linearly to Hammett constants of these substituted groups. PMID:26344376
[Review of digital ground object spectral library].
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. PMID:19810544
NASA Astrophysics Data System (ADS)
Kumar, Rakesh; Obrai, Sangeeta; Mitra, Joyee; Sharma, Aparna
2013-11-01
The structures and some spectral parameters of three copper(II) complexes; [Cu(THEEN)(H2O)](PIC)2 (1), [Cu(THPEN)] (PIC)2 C3H8O (2) and [Cu(TEAH3)(PIC)] (PIC)ṡ(H2O) (3), previously synthesized and characterized by X-ray diffraction, are here computationally studied by using density functional theory (DFT) in its hybrid form B3LYP. In these complexes, THEEN is N,N,N‧,N″-tetrakis(2-hydroxyethyl) ethylenediamine and THPEN is N,N,N‧,N″-tetrakis(2-hydroxypropyl) ethylenediamine, tetrapodal ligands and TEAH3 is tris(2-hydroxyethyl)amine, a tripodal ligand. The primary coordination sphere of copper(II) ion in complexes (1), (2) and (3) are optimized, structural parameters are calculated, vibrational bands are assigned and energy gaps of frontier orbital (HOMO-LUMO) have been calculated with B3LYP/6-31G/LANL2DZ level of theory using DMSO as solvent. The calculated geometric and spectral results reproduced the experimental data with well agreement. Theoretical calculated molecular orbitals (HOMO-LUMO) and their energies have been calculated that suggest charge transfer occurs within the complexes.
Soil spectral characterization
NASA Technical Reports Server (NTRS)
Stoner, E. R.; Baumgardner, M. F.
1981-01-01
The spectral characterization of soils is discussed with particular reference to the bidirectional reflectance factor as a quantitative measure of soil spectral properties, the role of soil color, soil parameters affecting soil reflectance, and field characteristics of soil reflectance. Comparisons between laboratory-measured soil spectra and Landsat MSS data have shown good agreement, especially in discriminating relative drainage conditions and organic matter levels in unvegetated soils. The capacity to measure both visible and infrared soil reflectance provides information on other soil characteristics and makes it possible to predict soil response to different management conditions. Field and laboratory soil spectral characterization helps define the extent to which intrinsic spectral information is available from soils as a consequence of their composition and field characteristics.
NASA Astrophysics Data System (ADS)
Gordon, I. E.; Rothman, L. S.; Toon, G. C.
2011-06-01
Until recently the B (B1ΣG+ (v=1)←X3Σ-G (v=0)) and γ (B1ΣG+ (v=2)←X3Σ-G (v=0)) bands of oxygen in the visible region had not been used extensively in satellite remote sensing. However, these bands (in particular the B-band) are now being considered for future satellite missions. In this light, it is important to make sure that the reference spectroscopic parameters are accurate enough to provide means of deducing important physical characteristics from the atmospheric spectra. The energy levels and intensities currently given for these bands in the HITRAN spectroscopic database had not been updated for over two decades. We have collected the best available measured line positions that involve the B1ΣG+ (v=1 and v=2) states for the three most abundant isotopologues of oxygen and performed a combined fit to obtain a consistent set of spectroscopic constants. These constants were then used to calculate the line positions. A careful review of the available intensity and line-shape measurements was also carried out, and new parameters were derived based on that review. In particular, line shift parameters that were not previously available were introduced. The new data have been tested in application to high-resolution atmospheric spectra measured with the Fourier transform spectrometers at Park Falls, WI (B-band) and Kitt Peak, AZ (γ-band) and have yielded substantial improvement. In addition, we report the first direct observation and analysis of the 16O18O lines in the γ-band. L.S. Rothman, I.E. Gordon, A. Barbe, D.Chris Benner, P.F. Bernath, et al, ``The HITRAN 2008 Molecular Spectroscopic Database,'' JQSRT 110, 532-572 (2009).
Parametric Explosion Spectral Model
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.
Strom, R; Blumberg, W E; Dale, R E; Crifo, C
1976-01-01
The variations of optical density and fluorescence of lucensomycin are good indices of the binding of this polyenic antibiotic to membranes. The former parameter reflects more generally the binding to any site present in the membrane, while the latter is more specific for binding to cholesterol. The chromophore of the lucensomycin-cholesterol complex has a relatively long lifetime, is almost immobile in the membrane, and is not accessible to water-soluble fluorescence-quenching agents. The stoichiometry, evaluated fluorometrically, corresponds to about two cholesterol molecules per polyene. In colloidal cholesterol suspensions, the extent of binding as a function of free polyene concentration is described by rectangular hyperbolae, the dissociation constant being, however, dependent on the sterol concentration. In erythrocyte membranes, on the other hand, and even more markedly in model systems containing appropriate solvents, the combination between lucensomycin and the sterol sites is described by sigmoid titration curves, indicative of cooperative effects, and probably due to solvation of cholesterol. PMID:974222
NASA Technical Reports Server (NTRS)
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.
NASA Astrophysics Data System (ADS)
Zeyada, H. M.; Makhlouf, M. M.; El-Nahass, M. M.
2015-09-01
In this work, we report on the effect of γ-ray irradiation and annealing temperature on the optical properties of metal-free tetraphenylporphyrin, H2TPP, and zinc tetraphenylporphyrin, ZnTPP, thin films. Thin films of H2TPP and ZnTPP were successfully prepared by the thermal evaporation technique. The optical properties of H2TPP and ZnTPP films were investigated using spectrophotometric measurements of the transmittance and reflectance at normal incidence of light in the wavelength range from 200 to 2500 nm. The absorption spectra of H2TPP showed four absorption bands, namely the Q, B, N and M bands. The effect of inserting Zn atom into the cavity of porphyrin macrocycle in ZnTPP molecule distorted the Q and B bands, reduced the width of absorption region and influenced the optical constants and dispersion parameters. In all conditions, the type of electron transition is indirect allowed transition. Anomalous dispersion is observed in the absorption region but normal dispersion occurs in the transparent region of spectra. We adopted multi-oscillator model and the single oscillator model to interpret the anomalous and normal dispersion, respectively. We have found that the annealing temperature has mostly the opposite effect of γ-ray irradiation on absorption and dispersion characteristics of these films.
NASA Astrophysics Data System (ADS)
Quinet, Pascal
2015-08-01
Heavy atoms and ions of the periodic table, in particular those with Z > 36, have been rather little investigated up to until very recently, due to the numerous difficulties met both on the theoretical and on the experimental sides. In relation with the recent needs in astrophysics, the situtaion has considerably evolved over the past few years and substantial progress has been reported. This progress has been made easier by the developments of theoretical methods and also by the extensive use of laser spectroscopy.Having in mind the astrophysical context, we have started a systematic investigation of radiative parameters of these ions (neutral, singly and doubly ionized elements) about 15 years ago. As a consequence, a large number of new results have been obtained. About 700 radiative lifetimes have been measured by time-resolved laser-induced fluorescence spectroscopy. The combination of these lifetimes with theoretical (and, when possible, experimental) branching fractions has led to transition probabilities for about 100000 transitions in atoms and ions belonging to the lanthanide group as well as to the fifth and the sixth rows of the periodic table.
Quantum graph as a quantum spectral filter
Turek, Ondrej; Cheon, Taksu
2013-03-15
We study the transmission of a quantum particle along a straight input-output line to which a graph {Gamma} is attached at a point. In the point of contact we impose a singularity represented by a certain properly chosen scale-invariant coupling with a coupling parameter {alpha}. We show that the probability of transmission along the line as a function of the particle energy tends to the indicator function of the energy spectrum of {Gamma} as {alpha}{yields}{infinity}. This effect can be used for a spectral analysis of the given graph {Gamma}. Its applications include a control of a transmission along the line and spectral filtering. The result is illustrated with an example where {Gamma} is a loop exposed to a magnetic field. Two more quantum devices are designed using other special scale-invariant vertex couplings. They can serve as a band-stop filter and as a spectral separator, respectively.
Duraev, V P; Marmalyuk, Aleksandr A; Padalitsa, A A; Petrovskii, A V; Ryaboshtan, Yu L; Sumarokov, M A; Sukharev, A V
2005-10-31
To improve the parameters of laser diodes emitting in the 1000-1070-nm spectral range and develop highly efficient laser diodes emitting in the 1070-1100-nm range, it is proposed to introduce GaAsP barrier layers into the active region of the quantum-well InGaAs/AlGaAs heterostructure, which compensate for enhanced mechanical stresses. This considerably improves the luminescence characteristics of heterostructures and changes conditions for generating misfit dislocations. The long-wavelength lasing at 1100 nm becomes possible due to an increase in the thickness of quantum wells and in the molar fraction of InAs in them. The manufactured laser diodes emitting in the 1095-1100-nm range have low threshold currents, the high output power and high reliability. (lasers)
NASA Astrophysics Data System (ADS)
Lang, Harold R.
1991-09-01
Stratigraphic and structural studies of the Wind River and Bighorn basins, Wyoming, and the Guerrero-Morelos basin, Mexico, have resulted in development of ''spectral stratigraphy.'' This approach to stratigraphic analysis 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. This paper reviews selected published examples that illustrate this new stratigraphic procedure. Visible to thermal infrared laboratory, spectral measurements of sedimentary rocks are the physical basis for spectral stratigraphy. Results show that laboratory, field, and remote spectroscopy can augment conventional laboratory and field methods for petrologic analysis, stratigraphic correlation, interpretation of depositional environments, and construction of facies models. Landsat thematic mapper data are used to map strata and construct stratigraphic columns and structural cross sections at 1:24,000 scale or less. Experimental multispectral thermal infrared aircraft data facilitate lithofacies/biofacies analyses. Visible short-wavelength infrared imaging spectrometer data allow remote determination of the stratigraphic distribution of iron oxides, quartz, calcite, dolomite, gypsum, specific clay species, and other minerals diagnostic of environments of deposition. Development of a desk-top, computer-based, geologic analysis system that provides for automated application of these approaches to coregistered digital image and topographic data portends major expansion in the use of spectral stratigraphy for purely scientific (lithospheric research) or practical (resource exploration) objectives.
[A Terahertz Spectral Database Based on Browser/Server Technique].
Zhang, Zhuo-yong; Song, Yue
2015-09-01
With the solution of key scientific and technical problems and development of instrumentation, the application of terahertz technology in various fields has been paid more and more attention. Owing to the unique characteristic advantages, terahertz technology has been showing a broad future in the fields of fast, non-damaging detections, as well as many other fields. Terahertz technology combined with other complementary methods can be used to cope with many difficult practical problems which could not be solved before. One of the critical points for further development of practical terahertz detection methods depends on a good and reliable terahertz spectral database. We developed a BS (browser/server) -based terahertz spectral database recently. We designed the main structure and main functions to fulfill practical requirements. The terahertz spectral database now includes more than 240 items, and the spectral information was collected based on three sources: (1) collection and citation from some other abroad terahertz spectral databases; (2) collected from published literatures; and (3) spectral data measured in our laboratory. The present paper introduced the basic structure and fundament functions of the terahertz spectral database developed in our laboratory. One of the key functions of this THz database is calculation of optical parameters. Some optical parameters including absorption coefficient, refractive index, etc. can be calculated based on the input THz time domain spectra. The other main functions and searching methods of the browser/server-based terahertz spectral database have been discussed. The database search system can provide users convenient functions including user registration, inquiry, displaying spectral figures and molecular structures, spectral matching, etc. The THz database system provides an on-line searching function for registered users. Registered users can compare the input THz spectrum with the spectra of database, according to
Commission 45: Spectral Classification
NASA Astrophysics Data System (ADS)
Giridhar, Sunetra; Gray, Richard O.; Corbally, Christopher J.; Bailer-Jones, Coryn A. L.; Eyer, Laurent; Irwin, Michael J.; Kirkpatrick, J. Davy; Majewski, Steven; Minniti, Dante; Nordström, Birgitta
This report gives an update of developments (since the last General Assembly at Prague) in the areas that are of relevance to the commission. In addition to numerous papers, a new monograph entitled Stellar Spectral Classification with Richard Gray and Chris Corbally as leading authors will be published by Princeton University Press as part of their Princeton Series in Astrophysics in April 2009. This book is an up-to-date and encyclopedic review of stellar spectral classification across the H-R diagram, including the traditional MK system in the blue-violet, recent extensions into the ultraviolet and infrared, the newly defined L-type and T-type spectral classes, as well as spectral classification of carbon stars, S-type stars, white dwarfs, novae, supernovae and Wolf-Rayet stars.
Visible and Near Infrared Fluorescence Spectral Flow Cytometry
Nolan, John P.; Condello, Danilo; Duggan, Erika; Naivar, Mark; Novo, David
2013-01-01
There is a long standing interest in measuring complete emission spectra from individual cells in flow cytometry. We have developed flow cytometry instruments and analysis approaches to enable this to be done routinely and robustly. Our spectral flow cytometers use a holographic grating to disperse light from single cells onto a CCD for high speed, wavelength-resolved detection. Customized software allows the single cell spectral data to be displayed and analyzed to produce new spectra-derived parameters. We show that familiar reference and calibration beads can be employed to quantitatively assess instrument performance. We use microspheres stained with six different quantum dots to compare a virtual bandpass filter approach with classic least squares (CLS) spectral unmixing, and then use antibody capture beads and CLS unmixing to demonstrate immunophenotyping of peripheral blood mononuclear cells using spectral flow cytometry. Finally, we characterize and evaluate several near infrared (NIR) emitting fluorophores for use in spectral flow cytometry. Spectral flow cytometry offers a number of attractive features for single cell analysis, including a simplified optical path, high spectral resolution, and streamlined approaches to quantitative multiparameter measurements. The availability of robust instrumentation, software, and analysis approaches will facilitate the development of spectral flow cytometry applications. PMID:23225549
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.
Thermophotovoltaic Spectral Control
DM DePoy; PM Fourspring; PF Baldasaro; JF Beausang; EJ Brown; MW Dashiel; KD Rahner; TD Rahmlow; JE Lazo-Wasem; EJ Gratrix; B Wemsman
2004-06-09
Spectral control is a key technology for thermophotovoltaic (TPV) direct energy conversion systems because only a fraction (typically less than 25%) of the incident thermal radiation has energy exceeding the diode bandgap energy, E{sub g}, and can thus be converted to electricity. The goal for TPV spectral control in most applications is twofold: (1) Maximize TPV efficiency by minimizing transfer of low energy, below bandgap photons from the radiator to the TPV diode. (2) Maximize TPV surface power density by maximizing transfer of high energy, above bandgap photons from the radiator to the TPV diode. TPV spectral control options include: front surface filters (e.g. interference filters, plasma filters, interference/plasma tandem filters, and frequency selective surfaces), back surface reflectors, and wavelength selective radiators. System analysis shows that spectral performance dominates diode performance in any practical TPV system, and that low bandgap diodes enable both higher efficiency and power density when spectral control limitations are considered. Lockheed Martin has focused its efforts on front surface tandem filters which have achieved spectral efficiencies of {approx}83% for E{sub g} = 0.52 eV and {approx}76% for E{sub g} = 0.60 eV for a 950 C radiator temperature.
Spectral averaging techniques for Jacobi matrices
Rio, Rafael del; Martinez, Carmen; Schulz-Baldes, Hermann
2008-02-15
Spectral averaging techniques for one-dimensional discrete Schroedinger operators are revisited and extended. In particular, simultaneous averaging over several parameters is discussed. Special focus is put on proving lower bounds on the density of the averaged spectral measures. These Wegner-type estimates are used to analyze stability properties for the spectral types of Jacobi matrices under local perturbations.
Kim, Sangtae; Gupta, Nitin; Bandeira, Nuno; Pevzner, Pavel A.
2009-01-01
Database search tools identify peptides by matching tandem mass spectra against a protein database. We study an alternative approach when all plausible de novo interpretations of a spectrum (spectral dictionary) are generated and then quickly matched against the database. We present a new MS-Dictionary algorithm for efficiently generating spectral dictionaries and demonstrate that MS-Dictionary can identify spectra that are missed in the database search. We argue that MS-Dictionary enables proteogenomics searches in six-frame translation of genomic sequences that may be prohibitively time-consuming for existing database search approaches. We show that such searches allow one to correct sequencing errors and find programmed frameshifts. PMID:18703573
Ibarria, L; Lindstrom, P; Rossignac, J
2006-11-17
Many scientific, imaging, and geospatial applications produce large high-precision scalar fields sampled on a regular grid. Lossless compression of such data is commonly done using predictive coding, in which weighted combinations of previously coded samples known to both encoder and decoder are used to predict subsequent nearby samples. In hierarchical, incremental, or selective transmission, the spatial pattern of the known neighbors is often irregular and varies from one sample to the next, which precludes prediction based on a single stencil and fixed set of weights. To handle such situations and make the best use of available neighboring samples, we propose a local spectral predictor that offers optimal prediction by tailoring the weights to each configuration of known nearby samples. These weights may be precomputed and stored in a small lookup table. We show that predictive coding using our spectral predictor improves compression for various sources of high-precision data.
Sigernes, F; Lorentzen, D A; Heia, K; Svenøe, T
2000-06-20
A small spectral imaging system is presented that images static or moving objects simultaneously as a function of wavelength. The main physical principle is outlined and demonstrated. The instrument is capable of resolving both spectral and spatial information from targets throughout the entire visible region. The spectral domain has a bandpass of 12 A. One can achieve the spatial domain by rotating the system's front mirror with a high-resolution stepper motor. The spatial resolution range from millimeters to several meters depends mainly on the front optics used and whether the target is fixed (static) or movable relative to the instrument. Different applications and examples are explored, including outdoor landscapes, industrial fish-related targets, and ground-level objects observed in the more traditional way from an airborne carrier (remote sensing). Through the examples, we found that the instrument correctly classifies whether a shrimp is peeled and whether it can disclose the spectral and spatial microcharacteristics of targets such as a fish nematode (parasite). In the macroregime, we were able to distinguish a marine vessel from the surrounding sea and sky. A study of the directional spectral albedo from clouds, mountains, snow cover, and vegetation has also been included. With the airborne experiment, the imager successfully classified snow cover, leads, and new and rafted ice, as seen from 10.000 ft (3.048 m). PMID:18345245
Interactive software for spectral assignment
NASA Technical Reports Server (NTRS)
Mielke, R. R.; Carraway, P. I.; Marefat, M.
1985-01-01
A new interactive computer software package for eigenvalue/eigenvector assignment using constant state feedback is described. The package consists of ten subprograms, each associated with a specific design objective, accessible from a main control program. Using this package, primary design objectives of assigning eigenvalues and approximating eigenvectors are first achieved. Then secondary design objectives, including modification of specific eigenvector components, reduction in specified elements of the feedback gain matrix, and reduction in eigensystem sensitivity to changes in plant parameters, are addressed. These secondary objectives are achieved by a systematic modification of the assigned eigenvectors in a small region about the initial assignment. In addition, the program implements the use of spectral assignment procedures with reduced-order system models. Program modes are described and illustrated by numerical examples.
The analytical design of spectral measurements for multispectral remote sensor systems
NASA Technical Reports Server (NTRS)
Wiersma, D. J.; Landgrebe, D. A. (Principal Investigator)
1979-01-01
The author has identified the following significant results. In order to choose a design which will be optimal for the largest class of remote sensing problems, a method was developed which attempted to represent the spectral response function from a scene as accurately as possible. The performance of the overall recognition system was studied relative to the accuracy of the spectral representation. The spectral representation was only one of a set of five interrelated parameter categories which also included the spatial representation parameter, the signal to noise ratio, ancillary data, and information classes. The spectral response functions observed from a stratum were modeled as a stochastic process with a Gaussian probability measure. The criterion for spectral representation was defined by the minimum expected mean-square error.
NASA Astrophysics Data System (ADS)
Rego, D.; Prangé, R.; Ben Jaffel, L.
1999-03-01
In this paper, third of a series of three dealing with a model of auroral H and H2 emission in the giant planets, we focus on the characteristics of the emergent emission, the only one which can be compared with observations. As the Jovian atmosphere is optically thick at 1215.67 Å, modeling of emergent auroral Lyman α line profiles requires the use of a radiative transfer code to model the transport of photons from the auroral source to the top of the atmosphere. Here, radiative transfer effects are modeled using the ``doubling and adding'' method. This radiative transfert code is self-consistently coupled with the energy degradation code used in the first two papers to compute the excitation rate along the path of precipitating particles as a function of wavelength. Input parameters are the identity and the energy of the incoming particles. We find that the auroral Lyman α line profile shows a central reversal due to the atmospheric H overlying the emitting layer. The shape of the emergent line is almost only sensitive to the column of H in the line of sight to the emission, related, via the atmospheric model used, to the the particle penetration depth (i.e. their energy). In addition, in the case of proton precipitation, charge exchange produces fast H atoms (Hf) which precipitate with the protons. Hf can also be excited and radiate Lyman α photons. This produces a second, Doppler shifted, component, of the Lyman α profile. This component may represent as much as 77.4% of the total Lyman α intensity for 10 keV protons, and it decreases with incident proton energy. It also extends over a broad wavelength range (up to 56 Å for 1 MeV proton). Detection of this component would unambiguously identify protons as the particles responsible for the Jovian aurorae. However, for high proton energies, the escaping flux may be too weak to be detected. Finally, following earlier analyses of IUE auroral spectra, we compute the color ratio C between the fluxes escaping
[Radiation thermometry based on calibration of spectral responsivity].
Xin, Cheng-Yun; Cheng, Xiao-Fang; Zhang, Zhong-Zheng
2012-10-01
Abstract True surface temperatures can be determined by measurements of radiation emitted by the object. The non-spectral parameter in the radiation measurement equation is the function of the relative position between the target and the lens, so calibration of space position is necessary for temperature measurement, when emissivity and temperature are measured simultaneously. In the present paper, the non-spectral parameter was included into the undetermined coefficients of emissivity modeled by finite series, which will not affect the solution of true surface temperature. Therefore, radiation thermometry can be accomplished without calibration of space position and normalization of measurement data. And not the true spectral emissivity but the trend of it can be measured. Two special examples were investigated, respectively. The results indicate that when the effective wavelength of each channel is different, multi-wavelength radiation thermometry equations have the unique solution, while the number of the multiband ones may be zero, one, two or even three. PMID:23285877
Method of multivariate spectral analysis
Keenan, Michael R.; Kotula, Paul G.
2004-01-06
A method of determining the properties of a sample from measured spectral data collected from the sample by performing a multivariate spectral analysis. The method can include: generating a two-dimensional matrix A containing measured spectral data; providing a weighted spectral data matrix D by performing a weighting operation on matrix A; factoring D into the product of two matrices, C and S.sup.T, by performing a constrained alternating least-squares analysis of D=CS.sup.T, where C is a concentration intensity matrix and S is a spectral shapes matrix; unweighting C and S by applying the inverse of the weighting used previously; and determining the properties of the sample by inspecting C and S. This method can be used to analyze X-ray spectral data generated by operating a Scanning Electron Microscope (SEM) with an attached Energy Dispersive Spectrometer (EDS).
Measures of Spectral Slope Using an Excised Larynx Model
Alipour, Fariborz; Scherer, Ronald C.; Finnegan, Eileen
2011-01-01
Spectral measures of the glottal source were investigated using an excised canine larynx model for various aerodynamic and phonatory conditions. These measures included spectral harmonic difference H1-H2 and spectral slope that are highly correlated with voice quality but not reported in a systematic manner using an excised larynx model. It was hypothesized that the acoustic spectra of the glottal source were significantly influenced by the subglottal pressure, glottal adduction, and vocal fold elongation, and the resulting vibration pattern. Canine larynges were prepared, mounted on the bench with and without false vocal folds, and made to oscillate with flow of heated and humidified air. Major control parameters were subglottal pressure, adduction, and elongation. Electroglottograph (EGG), subglottal pressure, flowrate, and audio signals were analyzed using custom software. Results suggest that an increase in subglottal pressure and glottal adduction may change the energy balance between harmonics by increasing the spectral energy of the first few harmonics in an unpredictable manner. It is suggested that changes in the dynamics of vocal fold motion may be responsible for different spectral patterns. The finding that the spectral harmonics do not conform to previous findings was demonstrated through various cases. Results of this study may shed light on phonatory spectral control when the larynx is part of a complete vocal tract system. PMID:22056893
Spectral Morphology for Feature Extraction from Multi- and Hyper-spectral Imagery.
Harvey, N. R.; Porter, R. B.
2005-01-01
For accurate and robust analysis of remotely-sensed imagery it is necessary to combine the information from both spectral and spatial domains in a meaningful manner. The two domains are intimately linked: objects in a scene are defined in terms of both their composition and their spatial arrangement, and cannot accurately be described by information from either of these two domains on their own. To date there have been relatively few methods for combining spectral and spatial information concurrently. Most techniques involve separate processing for extracting spatial and spectral information. In this paper we will describe several extensions to traditional morphological operators that can treat spectral and spatial domains concurrently and can be used to extract relationships between these domains in a meaningful way. This includes the investgation and development of suitable vector-ordering metrics and machine-learning-based techniques for optimizing the various parameters of the morphological operators, such as morphological operator, structuring element and vector ordering metric. We demonstrate their application to a range of multi- and hyper-spectral image analysis problems.
Parameters Describing Earth Observing Remote Sensing Systems
NASA Technical Reports Server (NTRS)
Zanoni, Vicki; Ryan, Robert E.; Pagnutti, Mary; Davis, Bruce; Markham, Brian; Storey, Jim
2003-01-01
The Earth science community needs to generate consistent and standard definitions for spatial, spectral, radiometric, and geometric properties describing passive electro-optical Earth observing sensors and their products. The parameters used to describe sensors and to describe their products are often confused. In some cases, parameters for a sensor and for its products are identical; in other cases, these parameters vary widely. Sensor parameters are bound by the fundamental performance of a system, while product parameters describe what is available to the end user. Products are often resampled, edge sharpened, pan-sharpened, or compressed, and can differ drastically from the intrinsic data acquired by the sensor. Because detailed sensor performance information may not be readily available to an international science community, standardization of product parameters is of primary performance. Spatial product parameters described include Modulation Transfer Function (MTF), point spread function, line spread function, edge response, stray light, edge sharpening, aliasing, ringing, and compression effects. Spectral product parameters discussed include full width half maximum, ripple, slope edge, and out-of-band rejection. Radiometric product properties discussed include relative and absolute radiometry, noise equivalent spectral radiance, noise equivalent temperature diffenence, and signal-to-noise ratio. Geometric product properties discussed include geopositional accuracy expressed as CE90, LE90, and root mean square error. Correlated properties discussed include such parameters as band-to-band registration, which is both a spectral and a spatial property. In addition, the proliferation of staring and pushbroom sensor architectures requires new parameters to describe artifacts that are different from traditional cross-track system artifacts. A better understanding of how various system parameters affect product performance is also needed to better ascertain the
Evolutionary Computing Methods for Spectral Retrieval
NASA Technical Reports Server (NTRS)
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.
Stark Widths of Spectral Lines of Neutral Neon
NASA Astrophysics Data System (ADS)
Dimitrijević, Milan S.; Simić, Zoran; Kovačević, Andjelka; Valjarević, Aleksandar; Sahal-Bréchot, Sylvie
2015-12-01
In order to complete Stark broadening data for Ne I spectral lines which are needed for analysis of stellar atmospheres, collisional widths and shifts (the so-called Stark broadening parameters) of 29 isolated spectral lines of neutral neon have been determined within the impact semiclassical perturbation method. Calculations have been performed for the broadening by collisions with electrons, protons and ionized helium for astrophysical applications, and for collisions with ionized neon and argon for laboratory plasma diagnostics. The shifts have been compared with existing experimental values. The obtained data will be included in the STARK-B database, which is a part of the Virtual Atomic and Molecular Data Center - VAMDC.
Soule, D E; Smith, D W
1977-11-01
A study was made to characterize parametrically the spectrally selective absorptance profiles of typical interference, bulk absorption, and mixed-type absorbing layers for solar-thermal conversion at temperatures to 500 degrees C. A five parameter empirical Fermi function was used to model the spectral absorptance converted from the measured spectral reflectance. An alternative method using the Fermi model is presented for defining the ir spectral emittance profile, as scaled to the measured hemispherical total emittahce. PMID:20174248
Power spectral estimation algorithms
NASA Technical Reports Server (NTRS)
Bhatia, Manjit S.
1989-01-01
Algorithms to estimate the power spectrum using Maximum Entropy Methods were developed. These algorithms were coded in FORTRAN 77 and were implemented on the VAX 780. The important considerations in this analysis are: (1) resolution, i.e., how close in frequency two spectral components can be spaced and still be identified; (2) dynamic range, i.e., how small a spectral peak can be, relative to the largest, and still be observed in the spectra; and (3) variance, i.e., how accurate the estimate of the spectra is to the actual spectra. The application of the algorithms based on Maximum Entropy Methods to a variety of data shows that these criteria are met quite well. Additional work in this direction would help confirm the findings. All of the software developed was turned over to the technical monitor. A copy of a typical program is included. Some of the actual data and graphs used on this data are also included.
Radio-astro-tools and spectral cube
NASA Astrophysics Data System (ADS)
Ginsburg, Adam
2016-03-01
SpectralCube is a toolkit for efficiently handling and performing simple analysis of spectral data cubes. It was designed for use with ALMA and JVLA data, but is readily and easily applicable to other data cubes including optical and infrared IFUs. This 5-minute "lightning talk" gives a brief overview and update of spectral_cube & the radio-astro-tools packages.
Energy Science and Technology Software Center (ESTSC)
2001-11-01
SPEX enables the user to interactively create, display, compare, and analyze spectra (in particular gamma-ray spectra). It includes features from the INEEL GAUSS software series and the ORNL DAMM program. Input data is spectrum histograms, energy calibration, peakwidth calibrationb, and peak energy listgs. Output data includes new spectra created from projections, postscript for printing current view, summary log, gaussian fit log, exported energy calibratgion, exported peak lists and banana gates.
The Complete Spectral Catalog of Bright BATSE Gamma-Ray Bursts
NASA Technical Reports Server (NTRS)
Kaneko, Yuki; Preece, Robert D.; Briggs, Michael S.; Paciesas, William S.; Meegan, Charles A.; Band, David L.
2006-01-01
We present a systematic spectral analysis of 350 bright Gamma-Ray Bursts (GRBs) observed by the Burst and Transient Source Experiment (BATSE; approx. 30 keV - 2 MeV; including 17 short GRBs) with high energy and time resolution. Our sample was selected from the complete set of 2704 BATSE GRBs based on their energy fluence or peak photon flux values to assure good statistics. To obtain well-constrained, model-unbiased spectral parameters, a set of various photon models is used to fit each spectrum, and internal characteristics of each model are also investigated. A thorough analysis has been performed on 342 time-integrated and 8459 time-resolved burst spectra, and the effects of integration times in determining the spectral parameters are explored. The analysis results presented here provide the most detailed perspective of spectral aspects of the GRB prompt emission to date. Using the results, we study correlations among spectral parameters and spectral evolutions. The results of all spectral fits are available electronically in FITS format, from the High-Energy Astrophysics Science Archive Research Center (HEASARC).
Optical spectral singularities as threshold resonances
Mostafazadeh, Ali
2011-04-15
Spectral singularities are among generic mathematical features of complex scattering potentials. Physically they correspond to scattering states that behave like zero-width resonances. For a simple optical system, we show that a spectral singularity appears whenever the gain coefficient coincides with its threshold value and other parameters of the system are selected properly. We explore a concrete realization of spectral singularities for a typical semiconductor gain medium and propose a method of constructing a tunable laser that operates at threshold gain.
Spectral density of Cooper pairs in two level quantum dot-superconductors Josephson junction
NASA Astrophysics Data System (ADS)
Dhyani, A.; Rawat, P. S.; Tewari, B. S.
2016-09-01
In the present paper, we report the role of quantum dot energy levels on the electronic spectral density for a two level quantum dot coupled to s-wave superconducting leads. The theoretical arguments in this work are based on the Anderson model so that it necessarily includes dot energies, single particle tunneling and superconducting order parameter for BCS superconductors. The expression for single particle spectral function is obtained by using the Green's function equation of motion technique. On the basis of numerical computation of spectral function of superconducting leads, it has been found that the charge transfer across such junctions can be controlled by the positions and availability of the dot levels.
Characterization of Spectral Absorption Properties of Aerosols Using Satellite Observations
NASA Technical Reports Server (NTRS)
Torres, O.; Jethva, H.; Bhartia, P. K.; Ahn, C.
2012-01-01
The wavelength-dependence of aerosol absorption optical depth (AAOD) is generally represented in terms of the Angstrom Absorption Exponent (AAE), a parameter that describes the dependence of AAOD with wavelength. The AAE parameter is closely related to aerosol composition. Black carbon (BC) containing aerosols yield AAE values near unity whereas Organic carbon (OC) aerosol particles are associated with values larger than 2. Even larger AAE values have been reported for desert dust aerosol particles. Knowledge of spectral AAOD is necessary for the calculation of direct radiative forcing effect of aerosols and for inferring aerosol composition. We have developed a satellitebased method of determining the spectral AAOD of absorbing aerosols. The technique uses high spectral resolution measurements of upwelling radiation from scenes where absorbing aerosols lie above clouds as indicated by the UV Aerosol Index. For those conditions, the satellite measured reflectance (rho lambda) is approximately given by Beer's law rho lambda = rho (sub 0 lambda) e (exp -mtau (sub abs lambda)) where rho(sub 0 lambda) is the cloud reflectance, m is the geometric slant path and tau (sub abs lambda) is the spectral AAOD. The rho (sub 0 lambda) term is determined by means of radiative transfer calculations using as input the cloud optical depth derived as described in Torres et al. [JAS, 2012] that accounts for the effects of aerosol absorption. In the second step, corrections for molecular and aerosol scattering effects are applied to the cloud reflectance term, and the spectral AAOD is then derived by inverting the equation above. The proposed technique will be discussed in detail and application results will be presented. The technique can be easily applied to hyper-spectral satellite measurements that include UV such as OMI, GOME and SCIAMACHY, or to multi-spectral visible measurements by other sensors provided that the aerosol-above-cloud events are easily identified.
Spectral and spread-spectral teleportation
Humble, Travis S.
2010-06-15
We report how quantum information encoded into the spectral degree of freedom of a single-photon state may be teleported using a finite spectrally entangled biphoton state. We further demonstrate how the bandwidth of the teleported wave form can be controllably and coherently dilated using a spread-spectral variant of teleportation. We calculate analytical expressions for the fidelities of spectral and spread-spectral teleportation when complex-valued Gaussian states are transferred using a proposed experimental approach. Finally, we discuss the utility of these techniques for integrating broad-bandwidth photonic qubits with narrow-bandwidth receivers in quantum communication systems.
High temperature spectral gamma well logging
Normann, R.A.; Henfling, J.A.
1997-01-01
A high temperature spectral gamma tool has been designed and built for use in small-diameter geothermal exploration wells. Several engineering judgments are discussed regarding operating parameters, well model selection, and signal processing. An actual well log at elevated temperatures is given with spectral gamma reading showing repeatability.