West, A G; Goldsmith, G R; Matimati, I; Dawson, T E
2011-08-30
Previous studies have demonstrated the potential for large errors to occur when analyzing waters containing organic contaminants using isotope ratio infrared spectroscopy (IRIS). In an attempt to address this problem, IRIS manufacturers now provide post-processing spectral analysis software capable of identifying samples with the types of spectral interference that compromises their stable isotope analysis. Here we report two independent tests of this post-processing spectral analysis software on two IRIS systems, OA-ICOS (Los Gatos Research Inc.) and WS-CRDS (Picarro Inc.). Following a similar methodology to a previous study, we cryogenically extracted plant leaf water and soil water and measured the δ(2)H and δ(18)O values of identical samples by isotope ratio mass spectrometry (IRMS) and IRIS. As an additional test, we analyzed plant stem waters and tap waters by IRMS and IRIS in an independent laboratory. For all tests we assumed that the IRMS value represented the "true" value against which we could compare the stable isotope results from the IRIS methods. Samples showing significant deviations from the IRMS value (>2σ) were considered to be contaminated and representative of spectral interference in the IRIS measurement. Over the two studies, 83% of plant species were considered contaminated on OA-ICOS and 58% on WS-CRDS. Post-analysis, spectra were analyzed using the manufacturer's spectral analysis software, in order to see if the software correctly identified contaminated samples. In our tests the software performed well, identifying all the samples with major errors. However, some false negatives indicate that user evaluation and testing of the software are necessary. Repeat sampling of plants showed considerable variation in the discrepancies between IRIS and IRMS. As such, we recommend that spectral analysis of IRIS data must be incorporated into standard post-processing routines. Furthermore, we suggest that the results from spectral analysis be
Spectral variability of the particulate backscattering ratio
Whitmire, A. L.; Boss, E.; Cowles, T. J.; Pegau, W. S.
2007-05-01
The spectral dependency of the particulate backscattering ratio is relevant in the fields of ocean color inversion, light field modeling, and inferring particle properties from optical measurements. Aside from theoretical predictions for spherical, homogeneous particles, we have very limited knowledge of the actual in situ spectral variability of the particulate backscattering ratio. This work presents results from five research cruises that were conducted over a three-year period. Water column profiles of physical and optical properties were conducted across diverse aquatic environments that offered a wide range of particle populations. The main objective of this research was to examine the behavior of the spectral particulate backscattering ratio in situ, both in terms of its absolute magnitude and its variability across visible wavelengths, using over nine thousand 1-meter binned data points for each of five wavelengths of the spectral particulate backscattering ratio. Our analysis reveals no spectral dependence of the particulate backscattering ratio within our measurement certainty, and a geometric mean value of 0.013 for this dataset. This is lower than the commonly used value of 0.0183 from Petzold’s integrated volume scattering data. Within the first optical depth of the water column, the mean particulate backscattering ratio was 0.010.
Cecconi, Jaures
2011-01-01
G. Bottaro: Quelques resultats d'analyse spectrale pour des operateurs differentiels a coefficients constants sur des domaines non bornes.- L. Garding: Eigenfuction expansions.- C. Goulaouic: Valeurs propres de problemes aux limites irreguliers: applications.- G. Grubb: Essential spectra of elliptic systems on compact manifolds.- J.Cl. Guillot: Quelques resultats recents en Scattering.- N. Schechter: Theory of perturbations of partial differential operators.- C.H. Wilcox: Spectral analysis of the Laplacian with a discontinuous coefficient.
Spectral ratio method for measuring emissivity
Watson, K.
1992-01-01
The spectral ratio method is based on the concept that although the spectral radiances are very sensitive to small changes in temperature the ratios are not. Only an approximate estimate of temperature is required thus, for example, we can determine the emissivity ratio to an accuracy of 1% with a temperature estimate that is only accurate to 12.5 K. Selecting the maximum value of the channel brightness temperatures is an unbiased estimate. Laboratory and field spectral data are easily converted into spectral ratio plots. The ratio method is limited by system signal:noise and spectral band-width. The images can appear quite noisy because ratios enhance high frequencies and may require spatial filtering. Atmospheric effects tend to rescale the ratios and require using an atmospheric model or a calibration site. ?? 1992.
Bawadi Nor Faizah
2016-01-01
Full Text Available Research in the important parameters for modeling the dynamic behavior of soils has led to rapid development of the small strain stiffness and damping ratio for use in the seismic method. It is because, the experimental determination of the damping ratio is problematic, especially for hard soils sample. Many researchers have proved that the surface wave method is a reliable tool to determine shear wave velocity and damping ratio profiles at a site with very small strains level. Surface wave methods based on Rayleigh waves propagation and the resulting attenuation curve can become erroneous when higher modes contribute to the soil’s response. In this study, two approaches has been used to determine the shear strain amplitude and damping ratio of residual soils at small strain level using Spectral Analysis of Surface Wave (SASW method. One is to derive shear strain amplitude from the frequency-response curve and the other is to derive damping ratio from travel-time data. Then, the results are compared to the conventional method.
Carnevale Neto, Fausto; Pilon, Alan C.; Selegato, Denise M.; Freire, Rafael T.; Gu, Haiwei; Raftery, Daniel; Lopes, Norberto P.; Castro-Gamboa, Ian
2016-01-01
Dereplication based on hyphenated techniques has been extensively applied in plant metabolomics, thereby avoiding re-isolation of known natural products. However, due to the complex nature of biological samples and their large concentration range, dereplication requires the use of chemometric tools to comprehensively extract information from the acquired data. In this work we developed a reliable GC-MS-based method for the identification of non-targeted plant metabolites by combining the Ratio Analysis of Mass Spectrometry deconvolution tool (RAMSY) with Automated Mass Spectral Deconvolution and Identification System software (AMDIS). Plants species from Solanaceae, Chrysobalanaceae and Euphorbiaceae were selected as model systems due to their molecular diversity, ethnopharmacological potential, and economical value. The samples were analyzed by GC-MS after methoximation and silylation reactions. Dereplication was initiated with the use of a factorial design of experiments to determine the best AMDIS configuration for each sample, considering linear retention indices and mass spectral data. A heuristic factor (CDF, compound detection factor) was developed and applied to the AMDIS results in order to decrease the false-positive rates. Despite the enhancement in deconvolution and peak identification, the empirical AMDIS method was not able to fully deconvolute all GC-peaks, leading to low MF values and/or missing metabolites. RAMSY was applied as a complementary deconvolution method to AMDIS to peaks exhibiting substantial overlap, resulting in recovery of low-intensity co-eluted ions. The results from this combination of optimized AMDIS with RAMSY attested to the ability of this approach as an improved dereplication method for complex biological samples such as plant extracts. PMID:27747213
Fausto Carnevale Neto
2016-09-01
Full Text Available Dereplication based on hyphenated techniques has been extensively applied in plant metabolomics, avoiding re-isolation of known natural products. However, due to the complex nature of biological samples and their large concentration range, dereplication requires the use of chemometric tools to comprehensively extract information from the acquired data. In this work we developed a reliable GC-MS-based method for the identification of non-targeted plant metabolites by combining the Ratio Analysis of Mass Spectrometry deconvolution tool (RAMSY with Automated Mass Spectral Deconvolution and Identification System software (AMDIS. Plants species from Solanaceae, Chrysobalanaceae and Euphorbiaceae were selected as model systems due to their molecular diversity, ethnopharmacological potential and economical value. The samples were analyzed by GC-MS after methoximation and silylation reactions. Dereplication initiated with the use of a factorial design of experiments to determine the best AMDIS configuration for each sample, considering linear retention indices and mass spectral data. A heuristic factor (CDF, compound detection factor was developed and applied to the AMDIS results in order to decrease the false-positive rates. Despite the enhancement in deconvolution and peak identification, the empirical AMDIS method was not able to fully deconvolute all GC-peaks, leading to low MF values and/or missing metabolites. RAMSY was applied as a complementary deconvolution method to AMDIS to peaks exhibiting substantial overlap, resulting in recovery of low-intensity co-eluted ions. The results from this combination of optimized AMDIS with RAMSY attested to the ability of this approach as an improved dereplication method for complex biological samples such as plant extracts.
Van Noten, Koen; Lecocq, Thomas; Watlet, Arnaud; Camelbeeck, Thierry
2014-05-01
The H/V Spectral Ratio (HVSR) analysis of ambient seismic noise has been widely used to estimate the fundamental site resonance frequency in the context of site-effect characterisation. In regions of unknown subsurface structure, in which there is a significant acoustic impedance contrast between sediments and the underlying bedrock, HVSR can be a very powerful tool to map bedrock morphology and sediment thickness. Calibrating the power-law relationship between the variation in fundamental frequency and sediment thickness around these unknown sites is crucial for sediment thickness mapping. This empirical relationship can be easily calculated by conducting HVSR analysis of ambient noise measurements above boreholes with known bedrock depth. Additional local H/V measurements above near-surface geophysical profiles, for instance created by Electrical Resistivity Tomography (ERT), allow training and improving the power-law relationship for sites with a shallow bedrock depth. As the compaction of sediments influences the Vs, one has however to take into account that this empirical relationship can only be applied in relative small areas with a similar local geology. Between 2008 and 2010, a seismic swarm (MLmax = 3.2) occurred in a hilly area, 20 km SE of Brussels (Belgium). 60 of the 300 recorded events were felt/heard by the local residents and were reported in the corresponding 'Did You Feel It' internet inquiries held by Royal Observatory of Belgium. Several low-magnitude events show a distinct macroseismic intensity variation that can be explained by the geological site effect, i.e. the local sediment thickness, affecting the human perception of these earthquake-induced ground motions. In this presentation, we apply the above described methodology and discuss the results of a geophysical survey including ERT-profiling, ambient noise recording, HVSR analysis in Geopsy and DEM-modelling to characterise the local site effects. The resulting sediment thickness model
Van Noten, Koen; Lecocq, Thomas
2016-04-01
Estimating the resonance frequency (f0) and amplification factor of unconsolidated sediments by H/V spectral ratio (HVSR) analysis of seismic ambient noise has been widely used since Nakamura's proposal in 1989. To measure f0 properly, Nakamura suggested to perform microzonation surveys at night when the artificial microtremor is small and does not fully disrupt the ambient seismic noise. As nightly fieldwork is not always a reasonable demand, we propose an alternative workflow of Nakamura's technique to improve the quality of HVSR results obtained by ambient noise measurements of mobile stations during the day. This new workflow includes the automated H/V calculation of continuous seismic data of a stationary or permanent station installed near the microzonation site for as long as the survey lasts in order to control the error in the HVSR analysis obtained by the mobile stations. In this presentation, we apply this workflow on one year of seismic data at two different case studies; i.e. a rural site with a shallow bedrock depth of 30 m and an urban site (Brussels, capital of Belgium, bedrock depth of 110 m) where human activity is continuous 24h/day. By means of an automated python script, the fundamental peak frequency and the H/V amplitude are automatically picked from H/V spectra that are calculated from 50% overlapping, 30 minute windows during the whole year. Afterwards, the f0 and amplitude picks are averaged per hour/per day for the whole year. In both case studies, the H/V amplitude and the fundamental frequencies range considerable, up to ˜15% difference between the daily and nightly measurements. As bedrock depth is known from boreholes at both sites, we concluded that the nightly picked f0 is the true one. Our results thus suggest that changes in the determined f0 and H/V amplitude are dominantly caused by the human behaviour which is stored in the ambient seismic noise (e.g. later onset of traffic in a weekend, quiet Sundays, differences between
Ng, R.; Polet, J.
2016-12-01
Site response in sedimentary basins has been a topic of research interest for many decades due to the increased likelihood of earthquake damage from site amplification and resonance. We will present the results of our investigation of site response within the Los Angeles Basin through the application of the microtremor Horizontal-to-Vertical (H/V) spectral ratio method using the Geopsy software. This method was applied to 3-component broadband waveforms from the Los Angeles Syncline Seismic Interferometry Experiment (LASSIE). LASSIE is a collaborative, temporary, and dense array of 73 broadband seismometers that were active for a two-month period from October until November 2014, transecting the Los Angeles basin from Long Beach to La Puente. The data from this array enabled us to make measurements of small-scale lateral variations in the fundamental frequency, amplitude, and directional dependency of the H/V spectral ratio across this highly populated sedimentary basin. Data analysis and interpretation were conducted in accordance with the Site Effects Assessment Using Ambient Excitations (SESAME) guidelines. Our results show an average fundamental period at the basin center of 6-9.5 s and additional peaks in the spectral ratio curves at much shorter periods for sites at the basin edge. Long period H/V ratio peak amplitudes range from 2 - 5.5, with the highest values measured for the greater Long Beach area. We observe directional dependency in the frequency and amplitude of the long period peaks in the spectral ratio in proximity to the basin edge, which appears to correlate with the strike of the basin structure. We will show profiles of the H/V amplitudes and peak frequencies across the LA Basin and interpret our results in the context of site response results from other studies, as well as models of shallow and deeper basin structure.
Discrimination of periodontal diseases using diffuse reflectance spectral intensity ratios
Chandra Sekhar, Prasanth; Betsy, Joseph; Presanthila, Janam; Subhash, Narayanan
2012-02-01
This clinical study was to demonstrate the applicability of diffuse reflectance (DR) intensity ratio R620/R575 in the quantification and discrimination of periodontitis and gingivitis from healthy gingiva. DR spectral measurements were carried out with white-light illumination from 70 healthy sites in 30 healthy volunteers, and 63 gingivitis- and 58 periodontitis-infected sites in 60 patients. Clinical parameters such as probing pocket depth, clinical attachment level, and gingival index were recorded in patient population. Diagnostic accuracies for discrimination of gingivitis and periodontitis from healthy gingiva were determined by comparison of spectral signatures with clinical parameters. Divergence of average DR spectral intensity ratio between control and test groups was studied using analysis of variance. The mean DR spectrum on normalization at 620 nm showed marked differences between healthy tissue, gingivitis, and periodontitis. Hemoglobin concentration and apparent SO2 (oxygen saturation) were also calculated for healthy, gingivitis, and periodontitis sites. DR spectral intensities at 545 and 575 nm showed a decreasing trend with progression of disease. Among the various DR intensity ratios studied, the R620/R575 ratio provided a sensitivity of 90% and specificity of 94% for discrimination of healthy tissues from gingivitis and a sensitivity of 91% and specificity of 100% for discrimination of gingivitis from periodontitis.
SPECTRAL ANALYSIS OF RADIOXENON
Cooper, Matthew W.; Bowyer, Ted W.; Hayes, James C.; Heimbigner, Tom R.; Hubbard, Charles W.; McIntyre, Justin I.; Schrom, Brian T.
2008-09-23
Monitoring changes in atmospheric radioxenon concentrations is a major tool in the detection of an underground nuclear explosion. Ground based systems like the Automated Radioxenon Sampler /Analyzer (ARSA), the Swedish Unattended Noble gas Analyzer (SAUNA) and the Automatic portable radiometer of isotopes Xe (ARIX), can collect and detect several radioxenon isotopes by processing and transferring samples into a high efficiency beta-gamma coincidence detector. The high efficiency beta-gamma coincidence detector makes these systems highly sensitive to the radioxenon isotopes 133Xe, 131mXe, 133mXe and 135Xe. The standard analysis uses regions of interest (ROI) to determine the amount of a particular radioxenon isotope present. The ROI method relies on the peaks of interest falling within energy limits of the ROI. Some potential problems inherent in this method are the reliance on stable detector gains and a fixed resolution for each energy peak. In addition, when a high activity sample is measured there will be more interference among the ROI, in particular within the 133Xe, 133mXe, and 131mXe regions. A solution to some of these problems can be obtained through spectral fitting of the data. Spectral fitting is simply the fitting of the peaks using known functions to determine the number and relative peak positions and widths. By knowing this information it is possible to determine which isotopes are present. Area under each peak can then be used to determine an overall concentration for each isotope. Using the areas of the peaks several key detector characteristics can be determined: efficiency, energy calibration, energy resolution and ratios between interfering isotopes (Radon daughters).
Radioactive anomaly discrimination from spectral ratios
Maniscalco, James; Sjoden, Glenn; Chapman, Mac Clements
2013-08-20
A method for discriminating a radioactive anomaly from naturally occurring radioactive materials includes detecting a first number of gamma photons having energies in a first range of energy values within a predetermined period of time and detecting a second number of gamma photons having energies in a second range of energy values within the predetermined period of time. The method further includes determining, in a controller, a ratio of the first number of gamma photons having energies in the first range and the second number of gamma photons having energies in the second range, and determining that a radioactive anomaly is present when the ratio exceeds a threshold value.
Van Noten, K.; Lecocq, T.; Camelbeeck, T.
2013-12-01
Between 2008 and 2010, the Royal Observatory of Belgium received numerous ';Did You Feel It'-reports related to a 2-year lasting earthquake swarm at Court-Saint-Etienne, a small town in a hilly area 20 km SE of Brussels, Belgium. These small-magnitude events (-0.7 ≤ ML ≤ 3.2, n = c. 300 events) were recorded both by the permanent seismometer network in Belgium and by a locally installed temporary seismic network deployed in the epicentral area. Relocation of the hypocenters revealed that the seismic swarm can be related to the reactivation of a NW-SE strike-slip fault at 3 to 6 km depth in the basement rocks of the Lower Palaeozoic London-Brabant Massif. This sequence caused a lot of emotion in the region because more than 60 events were felt by the local population. Given the small magnitudes of the seismic swarm, most events were more often heard than felt by the respondents, which is indicative of a local high-frequency earthquake source. At places where the bedrock is at the surface or where it is covered by thin alluvial sediments ( 30 m). In those river valleys that have a considerable alluvial sedimentary cover, macroseismic intensities are again lower. To explain this variation in macroseismic intensity we present a macroseismic analysis of all DYFI-reports related to the 2008-2010 seismic swarm and a pervasive H/V spectral ratio (HVSR) analysis of ambient noise measurements to model the thickness of sediments covering the London-Brabant Massif. The HVSR method is a very powerful tool to map the basement morphology, particularly in regions of unknown subsurface structure. By calculating the soil's fundamental frequency above boreholes, we calibrated the power-law relationship between the fundamental frequency, shear wave velocity and the thickness of sediments. This relationship is useful for places where the sediment thickness is unknown and where the fundamental frequency can be calculated by H/V spectral ratio analysis of ambient noise. In a
Wyer, J C; Salzinger, F H
1983-01-01
Many common management techniques have little use in managing a medical group practice. Ratio analysis, however, can easily be adapted to the group practice setting. Acting as broad-gauge indicators, financial ratios provide an early warning of potential problems and can be very useful in planning for future operations. The author has gathered a collection of financial ratios which were developed by participants at an education seminar presented for the Virginia Medical Group Management Association. Classified according to the human element, system component, and financial factor, the ratios provide a good sampling of measurements relevant to medical group practices and can serve as an example for custom-tailoring a ratio analysis system for your medical group.
Kim, Duho; Windhorst, Rogier A
2016-01-01
We analyze the intrinsic flux ratios of various visible--near-infrared filters with respect to 3.5micron for simple and composite stellar populations, and their dependence on age, metallicity and star formation history. UV/optical light from stars is reddened and attenuated by dust, where different sightlines across a galaxy suffer varying amounts of extinction. Tamura et al. (2009) developed an approximate method to correct for dust extinction on a pixel-by-pixel basis, dubbed the "beta_V" method, by comparing the observed flux ratio to an empirical estimate of the intrinsic ratio of visible and ~3.5micron data. Through extensive modeling, we aim to validate the "beta_V" method for various filters spanning the visible through near-infrared wavelength range, for a wide variety of simple and composite stellar populations. Combining Starburst99 and BC03 models, we built spectral energy distributions (SEDs) of simple (SSP) and composite (CSP) stellar populations for various realistic star formation histories (SF...
Rapid spectral analysis for spectral imaging.
Jacques, Steven L; Samatham, Ravikant; Choudhury, Niloy
2010-07-15
Spectral imaging requires rapid analysis of spectra associated with each pixel. A rapid algorithm has been developed that uses iterative matrix inversions to solve for the absorption spectra of a tissue using a lookup table for photon pathlength based on numerical simulations. The algorithm uses tissue water content as an internal standard to specify the strength of optical scattering. An experimental example is presented on the spectroscopy of portwine stain lesions. When implemented in MATLAB, the method is ~100-fold faster than using fminsearch().
SPECTRAL ANALYSIS OF EXCHANGE RATES
ALEŠA LOTRIČ DOLINAR
2013-06-01
Full Text Available Using spectral analysis is very common in technical areas but rather unusual in economics and finance, where ARIMA and GARCH modeling are much more in use. To show that spectral analysis can be useful in determining hidden periodic components for high-frequency finance data as well, we use the example of foreign exchange rates
Using Spectral Flux Ratios to Standardize SN Ia Luminosities
Bailey, S; Antilogus, P; Aragon, C; Baltay, C; Bongard, S; Buton, C; Childress, M; Chotard, N; Copin, Y; Gangler, E; Loken, S; Nugent, P; Pain, R; Pécontal, E; Pereira, R; Perlmutter, S; Rabinowitz, D; Rigaudier, G; Runge, K; Scalzo, R; Smadja, G; Swift, H; Tao, C; Thomas, R C; Wu, C
2009-01-01
We present a new method to standardize Type Ia supernova (SN Ia) luminosities to ~<0.13 magnitudes using flux ratios from a single flux-calibrated spectrum per SN. Using Nearby Supernova Factory spectrophotomery of 58 SNe Ia, we performed an unbiased search for flux ratios which correlate with SN Ia luminosity. After developing the method and selecting the best ratios from a training sample, we verified the results on a separate validation sample and with data from the literature. We identified multiple flux ratios whose correlations with luminosity are stronger than those of light curve shape and color, previously identified spectral feature ratios, or equivalent width measurements. In particular, the flux ratio R(642/443) = F(642 nm) / F(443 nm) has a correlation of 0.95 with SN Ia absolute magnitudes. Using this single ratio as a correction factor produces a Hubble diagram with a residual scatter standard deviation of 0.125 +- 0.011 mag, compared with 0.161 +- 0.015 mag when fit with the SALT2 light cur...
[Research on the model of spectral unmixing for minerals based on derivative of ratio spectroscopy].
Zhao, Heng-Qian; Zhang, Li-Fu; Wu, Tai-Xia; Huang, Chang-Ping
2013-01-01
The precise analysis of mineral abundance is a key difficulty in hyperspectral remote sensing research. In the present paper, based on linear spectral mixture model, the derivative of ratio spectroscopy (DRS) was introduced for spectral unmixing of visible to short-wave infrared (Vis-SWIR; 0.4 - 2.5 microm) reflectance data. The mixtures of different proportions of plaster and allochite were analyzed to estimate the accuracy of the spectral unmixing model based on DRS. For the best 5 strong linear bands, the Pearson correlation coefficient (PCC) of the abundances and the actual abundances were higher than 99.9%, while the root mean square error (RMSE) is less than 2.2%. The result shows that the new spectral unmixing model based on DRS is simple, of rigorous mathematical proof, and highly precise. It has a great potential in high-precision quantitative analysis of spectral mixture with fixed endmembers.
Timescale Analysis of Spectral Lags
Ti-Pei Li; Jin-Lu Qu; Hua Feng; Li-Ming Song; Guo-Qiang Ding; Li Chen
2004-01-01
A technique for timescale analysis of spectral lags performed directly in the time domain is developed. Simulation studies are made to compare the time domain technique with the Fourier frequency analysis for spectral time lags. The time domain technique is applied to studying rapid variabilities of X-ray binaries and γ-ray bursts. The results indicate that in comparison with the Fourier analysis the timescale analysis technique is more powerful for the study of spectral lags in rapid variabilities on short time scales and short duration flaring phenomena.
Spectral Analysis of Markov Chains
2007-01-01
The paper deals with the problem of a statistical analysis of Markov chains connected with the spectral density. We present the expressions for the function of spectral density. These expressions may be used to estimate the parameter of the Markov chain.
Spectral Ratios for Crack Detection Using P and Rayleigh Waves
Enrique Olivera-Villaseñor
2012-01-01
Full Text Available We obtain numerical results to help the detection and characterization of subsurface cracks in solids by the application of P and Rayleigh elastic waves. The response is obtained from boundary integral equations, which belongs to the field of elastodynamics. Once the implementation of the boundary conditions has been done, a system of Fredholm integral equations of the second kind and order zero is found. This system is solved using the method of Gaussian elimination. Resonance peaks in the frequency domain allow us to infer the presence of cracks using spectral ratios. Several models of cracked media were analyzed, where effects due to different crack orientations and locations were observed. The results obtained are in good agreement with those published in the references.
Metwally, Fadia H; El-Saharty, Yasser S; Refaat, Mohamed; El-Khateeb, Sonia Z
2007-01-01
New selective, precise, and accurate methods are described for the determination of a ternary mixture containing drotaverine hydrochloride (I), caffeine (II), and paracetamol (III). The first method uses the first (D1) and third (D3) derivative spectrophotometry at 331 and 315 nm for the determination of (I) and (III), respectively, without interference from (II). The second method depends on the simultaneous use of the first derivative of the ratio spectra (DD1) with measurement at 312.4 nm for determination of (I) using the spectrum of 40 microg/mL (III) as a divisor or measurement at 286.4 and 304 nm after using the spectrum of 4 microg/mL (I) as a divisor for the determination of (II) and (III), respectively. In the third method, the predictive abilities of the classical least-squares, principal component regression, and partial least-squares were examined for the simultaneous determination of the ternary mixture. The last method depends on thin-layer chromatography-densitometry after separation of the mixture on silica gel plates using ethyl acetate-chloroform-methanol (16 + 3 + 1, v/v/v) as the mobile phase. The spots were scanned at 281, 272, and 248 nm for the determination of (I), (II), and (III), respectively. Regression analysis showed good correlation in the selected ranges with excellent percentage recoveries. The chemical variables affecting the analytical performance of the methodology were studied and optimized. The methods showed no significant interferences from excipients. Intraday and interday assay precision and accuracy values were within regulatory limits. The suggested procedures were checked using laboratory-prepared mixtures and were successfully applied for the analysis of their pharmaceutical preparations. The validity of the proposed methods was further assessed by applying a standard addition technique. The results obtained by applying the proposed methods were statistically analyzed and compared with those obtained by the manufacturer
Substitution dynamical systems spectral analysis
Queffélec, Martine
2010-01-01
This volume mainly deals with the dynamics of finitely valued sequences, and more specifically, of sequences generated by substitutions and automata. Those sequences demonstrate fairly simple combinatorical and arithmetical properties and naturally appear in various domains. As the title suggests, the aim of the initial version of this book was the spectral study of the associated dynamical systems: the first chapters consisted in a detailed introduction to the mathematical notions involved, and the description of the spectral invariants followed in the closing chapters. This approach, combined with new material added to the new edition, results in a nearly self-contained book on the subject. New tools - which have also proven helpful in other contexts - had to be developed for this study. Moreover, its findings can be concretely applied, the method providing an algorithm to exhibit the spectral measures and the spectral multiplicity, as is demonstrated in several examples. Beyond this advanced analysis, many...
SPAM- SPECTRAL ANALYSIS MANAGER (UNIX VERSION)
Solomon, J. E.
1994-01-01
The Spectral Analysis Manager (SPAM) was developed to allow easy qualitative analysis of multi-dimensional imaging spectrometer data. Imaging spectrometers provide sufficient spectral sampling to define unique spectral signatures on a per pixel basis. Thus direct material identification becomes possible for geologic studies. SPAM provides a variety of capabilities for carrying out interactive analysis of the massive and complex datasets associated with multispectral remote sensing observations. In addition to normal image processing functions, SPAM provides multiple levels of on-line help, a flexible command interpretation, graceful error recovery, and a program structure which can be implemented in a variety of environments. SPAM was designed to be visually oriented and user friendly with the liberal employment of graphics for rapid and efficient exploratory analysis of imaging spectrometry data. SPAM provides functions to enable arithmetic manipulations of the data, such as normalization, linear mixing, band ratio discrimination, and low-pass filtering. SPAM can be used to examine the spectra of an individual pixel or the average spectra over a number of pixels. SPAM also supports image segmentation, fast spectral signature matching, spectral library usage, mixture analysis, and feature extraction. High speed spectral signature matching is performed by using a binary spectral encoding algorithm to separate and identify mineral components present in the scene. The same binary encoding allows automatic spectral clustering. Spectral data may be entered from a digitizing tablet, stored in a user library, compared to the master library containing mineral standards, and then displayed as a timesequence spectral movie. The output plots, histograms, and stretched histograms produced by SPAM can be sent to a lineprinter, stored as separate RGB disk files, or sent to a Quick Color Recorder. SPAM is written in C for interactive execution and is available for two different
Deriving Light Interception and Biomass from Spectral Reflectance Ratio
Christensen, Svend; Goudriaan, J.
1993-01-01
the product of daily fPAR and incoming PAR (cumulative PAR interception) in all spring barley cultivars grown in monoculture and in mixture with oil seed rape (Brassica napus). A regression analysis showed that the relation between cumulative intercepted PAR and total above ground biomass was the same in all...... monocultures and mixtures. The ratio α of incremental dry matter and intercepted PAR was normally 2.4 g MJ−1, but it declined below this value when temperatures fell below 12°C....
Spectral analysis of bedform dynamics
Winter, Christian; Ernstsen, Verner Brandbyge; Noormets, Riko
. An assessment of bedform migration was achieved, as the growth and displacement of every single constituent can be distinguished. It can be shown that the changes in amplitude remain small for all harmonic constituents, whereas the phase shifts differ significantly. Thus the harmonics can be classified....... The proposed method overcomes the above mentioned problems of common descriptive analysis as it is an objective and straightforward mathematical process. The spectral decomposition of superimposed dunes allows a detailed description and analysis of dune patterns and migration....
Kaskaoutis, D. G.; Kambezidis, H. D.; Dumka, U. C.; Psiloglou, B. E.
2016-09-01
This study investigates the modification of the clear-sky spectral diffuse-direct irradiance ratio (DDR) as a function of solar zenith angle (SZA), spectral aerosol optical depth (AOD) and single scattering albedo (SSA). The solar spectrum under various atmospheric conditions is derived with Simple Model of the Atmospheric Radiative Transfer of Sunshine (SMARTS) radiative transfer code, using the urban and continental aerosol models as inputs. The spectral DDR can be simulated with great accuracy by an exponentially decreasing curve, while the aerosol optical properties strongly affect the scattering processes in the atmosphere, thus modifying the DDR especially in the ultraviolet (UV) spectrum. Furthermore, the correlation between spectral DDR and spectral AOD can be represented precisely by an exponential function and can give valuable information about the dominance of specific aerosol types. The influence of aerosols on spectral DDR increases with increasing SZA, while the simulations using the urban aerosol model as input in SMARTS are closer to the measurements taken in the Athens urban environment. The SMARTS simulations are interrelated with spectral measurements and can be used for indirect estimations of SSA. Overall, the current work provides some theoretical approximations and functions that help in understanding the dependence of DDR on astronomical and atmospheric parameters.
Spectral analysis by correlation; Analyse spectrale par correlation
Fauque, J.M.; Berthier, D.; Max, J.; Bonnet, G. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires
1969-07-01
The spectral density of a signal, which represents its power distribution along the frequency axis, is a function which is of great importance, finding many uses in all fields concerned with the processing of the signal (process identification, vibrational analysis, etc...). Amongst all the possible methods for calculating this function, the correlation method (correlation function calculation + Fourier transformation) is the most promising, mainly because of its simplicity and of the results it yields. The study carried out here will lead to the construction of an apparatus which, coupled with a correlator, will constitute a set of equipment for spectral analysis in real time covering the frequency range 0 to 5 MHz. (author) [French] La densite spectrale d'un signal qui represente la repartition de sa puissance sur l'axe des frequences est une fonction de premiere importance, constamment utilisee dans tout ce qui touche le traitement du signal (identification de processus, analyse de vibrations, etc...). Parmi toutes les methodes possibles de calcul de cette fonction, la methode par correlation (calcul de la fonction de correlation + transformation de Fourier) est tres seduisante par sa simplicite et ses performances. L'etude qui est faite ici va deboucher sur la realisation d'un appareil qui, couple a un correlateur, constituera un ensemble d'analyse spectrale en temps reel couvrant la gamme de frequence 0 a 5 MHz. (auteur)
Ambient noise H/V spectral ratio in site effects estimation in Fateh jang area, Pakistan
S.M.Talha Qadri; Bushra Nawaz; S.H.Sajjad; Riaz Ahmad Sheikh
2015-01-01
Local geology or local site effect is a crucial component while conducting seismic risk assessment studies.Investigations made by utilization of ambient noise are an effective tool for local site estimation.The present study is conducted to perform site response analysis at 13 different sites within urban settlements of Fateh jang area (Pakistan).The aim of this study was achieved by utilizing Nakamura method or H/V spectral ratio method.Some important local site parameters,e.g.,the fundamental frequencies f0 of soft sediments,amplitudes A0 of corresponding H/V spectral ratios,and alluvium thicknesses over 13 sites within the study area,were measured and analyzed.The results show that the study area reflects low fundamental frequency f0.The fundamental frequencies of the sediments are highly variable and lie in a range of 0.6-13.0 Hz.Similarly,amplification factors at these sites are in the range of 2.0-4.0.
Simplified Method for Experimental Spectral Ratio Calculation of CHG-FEL
Chen Nian; Li, Ge; Li, Yuhui; Zhang, Pengfei; Zhang, Shancai
2004-01-01
The goal of the coherent harmonic generation free-electron laser (CHG-FEL) experiment in NSRL is to gain a 266nm coherent radiation and a large spectral ratio which is defined as the ratio of coherent intensity to incoherent intensity in infinitesimal bandwidth and solid angle aperture. The intensity measurements are made through a spectrometer whose spectral and angular aperture is much larger than the actual apertures of coherent radiation and smaller than those of incoherent radiation. So the measured ratio is integral ratio integrated over the actual apertures of the measurement system. This paper is mainly on giving a formula and designing a computer program to calculate the spectral ratio according to the bandwidth and solid angle aperture of the measurement system, taking into account the measured magnetic field of optical klystron and the energy spread of the electron beam. The code will soon be employed in our next turn experiment.
Basic Functional Analysis Puzzles of Spectral Flow
Booss-Bavnbek, Bernhelm
2011-01-01
We explain an array of basic functional analysis puzzles on the way to general spectral flow formulae and indicate a direction of future topological research for dealing with these puzzles.......We explain an array of basic functional analysis puzzles on the way to general spectral flow formulae and indicate a direction of future topological research for dealing with these puzzles....
Swayze, G.A.; Clark, R.N.; Goetz, A.F.H.; Chrien, T.H.; Gorelick, N.S.
2003-01-01
Estimates of spectrometer band pass, sampling interval, and signal-to-noise ratio required for identification of pure minerals and plants were derived using reflectance spectra convolved to AVIRIS, HYDICE, MIVIS, VIMS, and other imaging spectrometers. For each spectral simulation, various levels of random noise were added to the reflectance spectra after convolution, and then each was analyzed with the Tetracorder spectra identification algorithm [Clark et al., 2003]. The outcome of each identification attempt was tabulated to provide an estimate of the signal-to-noise ratio at which a given percentage of the noisy spectra were identified correctly. Results show that spectral identification is most sensitive to the signal-to-noise ratio at narrow sampling interval values but is more sensitive to the sampling interval itself at broad sampling interval values because of spectral aliasing, a condition when absorption features of different materials can resemble one another. The band pass is less critical to spectral identification than the sampling interval or signal-to-noise ratio because broadening the band pass does not induce spectral aliasing. These conclusions are empirically corroborated by analysis of mineral maps of AVIRIS data collected at Cuprite, Nevada, between 1990 and 1995, a period during which the sensor signal-to-noise ratio increased up to sixfold. There are values of spectrometer sampling and band pass beyond which spectral identification of materials will require an abrupt increase in sensor signal-to-noise ratio due to the effects of spectral aliasing. Factors that control this threshold are the uniqueness of a material's diagnostic absorptions in terms of shape and wavelength isolation, and the spectral diversity of the materials found in nature and in the spectral library used for comparison. Array spectrometers provide the best data for identification when they critically sample spectra. The sampling interval should not be broadened to
Nanocatalytic resonance scattering spectral analysis
无
2010-01-01
The resonance scattering spectral technique has been established using the synchronous scanning technique on spectrofluorometry.Because of its advantages of simplicity,rapidity and sensitivity,it has been widely applied to analyses of proteins,nucleic acids and inorganic ions.This paper summarizes the application of immunonanogold and aptamer modified nanogold(AptAu) catalytic resonance scattering spectral technique in combination with the work of our group,citing 53 references.
Hochbaum, Dorit S
2010-01-01
Several challenging problem in clustering, partitioning and imaging have traditionally been solved using the "spectral technique". These problems include the normalized cut problem, the graph expander ratio problem, the Cheeger constant problem and the conductance problem. These problems share several common features: all seek a bipartition of a set of elements; the problems are formulated as a form of ratio cut; the formulation as discrete optimization is shown here to be equivalent to a quadratic ratio, sometimes referred to as the Raleigh ratio, on discrete variables and a single sum constraint which we call the balance or orthogonality constraint; when the discrete nature of the variables is disregarded, the continuous relaxation is solved by the spectral method. Indeed the spectral relaxation technique is a dominant method providing an approximate solution to these problems. We propose an algorithm for these problems which involves a relaxation of the orthogonality constraint only. This relaxation is sho...
Exoplanetary Detection by Multifractal Spectral Analysis
Agarwal, Sahil; Del Sordo, Fabio; Wettlaufer, John S.
2017-01-01
Owing to technological advances, the number of exoplanets discovered has risen dramatically in the last few years. However, when trying to observe Earth analogs, it is often difficult to test the veracity of detection. We have developed a new approach to the analysis of exoplanetary spectral observations based on temporal multifractality, which identifies timescales that characterize planetary orbital motion around the host star and those that arise from stellar features such as spots. Without fitting stellar models to spectral data, we show how the planetary signal can be robustly detected from noisy data using noise amplitude as a source of information. For observation of transiting planets, combining this method with simple geometry allows us to relate the timescales obtained to primary and secondary eclipse of the exoplanets. Making use of data obtained with ground-based and space-based observations we have tested our approach on HD 189733b. Moreover, we have investigated the use of this technique in measuring planetary orbital motion via Doppler shift detection. Finally, we have analyzed synthetic spectra obtained using the SOAP 2.0 tool, which simulates a stellar spectrum and the influence of the presence of a planet or a spot on that spectrum over one orbital period. We have demonstrated that, so long as the signal-to-noise-ratio ≥ 75, our approach reconstructs the planetary orbital period, as well as the rotation period of a spot on the stellar surface.
Burton, S. P.; Hair, J. W.; Kahnert, M.; Ferrare, R. A.; Hostetler, C. A.; Cook, A. L.; Harper, D. B.; Berkoff, T. A.; Seaman, S. T.; Collins, J. E.; Fenn, M. A.; Rogers, R. R.
2015-12-01
Linear particle depolarization ratio is presented for three case studies from the NASA Langley airborne High Spectral Resolution Lidar-2 HSRL-2). Particle depolarization ratio from lidar is an indicator of non-spherical particles and is sensitive to the fraction of non-spherical particles and their size. The HSRL-2 instrument measures depolarization at three wavelengths: 355, 532, and 1064 nm. The three measurement cases presented here include two cases of dust-dominated aerosol and one case of smoke aerosol. These cases have partial analogs in earlier HSRL-1 depolarization measurements at 532 and 1064 nm and in literature, but the availability of three wavelengths gives additional insight into different scenarios for non-spherical particles in the atmosphere. A case of transported Saharan dust has a spectral dependence with a peak of 0.30 at 532 nm with smaller particle depolarization ratios of 0.27 and 0.25 at 1064 and 355 nm, respectively. A case of aerosol containing locally generated wind-blown North American dust has a maximum of 0.38 at 1064 nm, decreasing to 0.37 and 0.24 at 532 and 355 nm, respectively. The cause of the maximum at 1064 nm is inferred to be very large particles that have not settled out of the dust layer. The smoke layer has the opposite spectral dependence, with the peak of 0.24 at 355 nm, decreasing to 0.09 and 0.02 at 532 and 1064 nm, respectively. The depolarization in the smoke case may be explained by the presence of coated soot aggregates. We note that in these specific case studies, the linear particle depolarization ratio for smoke and dust-dominated aerosol are more similar at 355 nm than at 532 nm, having possible implications for using the particle depolarization ratio at a single wavelength for aerosol typing.
An experimental system for spectral line ratio measurements in the TJ-II stellarator.
Zurro, B; Baciero, A; Fontdecaba, J M; Peláez, R; Jiménez-Rey, D
2008-10-01
The chord-integrated emissions of spectral lines have been monitored in the TJ-II stellarator by using a spectral system with time and space scanning capabilities and relative calibration over the entire UV-visible spectral range. This system has been used to study the line ratio of lines of different ionization stages of carbon (C(5+) 5290 A and C(4+) 2271 A) for plasma diagnostic purposes. The local emissivity of these ions has been reconstructed, for quasistationary profiles, by means of the inversion Fisher method described previously. The experimental line ratio is being empirically studied and in parallel a simple spectroscopic model has been developed to account for that ratio. We are investigating whether the role played by charge exchange processes with neutrals and the existence of non-Maxwellian electrons, intrinsic to Electron Cyclotron Resonance Heating (ECRH) heating, leave any distinguishable mark on this diagnostic method.
Carrasco-Hernandez, Roberto; Smedley, Andrew R. D.; Webb, Ann R.
2016-05-01
Two radiative transfer models are presented that simplify calculations of street canyon spectral irradiances with minimum data input requirements, allowing better assessment of urban exposures than can be provided by standard unobstructed radiation measurements alone. Fast calculations improve the computational performance of radiation models, when numerous repetitions are required in time and location. The core of the models is the calculation of the spectral diffuse-to-global ratios (DGR) from an unobstructed global spectral measurement. The models are based on, and have been tested against, outcomes of the SMARTS2 algorithm (i.e. Simple Model of the Atmospheric Radiative Transfer of Sunshine). The modelled DGRs can then be used to partition global spectral irradiance values into their direct and diffuse components for different solar zenith angles. Finally, the effects of canyon obstructions can be evaluated independently on the direct and diffuse components, which are then recombined to give the total canyon irradiance. The first model allows ozone and aerosol inputs, while the second provides a further simplification, restricted to average ozone and aerosol contents but specifically designed for faster calculations. To assess the effect of obstructions and validate the calculations, a set of experiments with simulated obstructions (simulated canyons) were performed. The greatest source of uncertainty in the simplified calculations is in the treatment of diffuse radiation. The measurement-model agreement is therefore dependent on the region of the sky obscured and ranges from <5 % at all wavelengths to 20-40 % (wavelength dependent) when diffuse sky only is visible from the canyon.
Lunar phase function effects on spectral ratios used for resource assessment
Larson, S. M.; Collins, J.; Singer, R. B.; Johnson, J. R.; Melendrez, D. E.
1993-01-01
Groundbased telescopic CCD images of 36 selected locations on the moon were obtained in five 'standard' bandpasses at 12 phase angles ranging from -78 deg to +75 deg to measure phase function effects on the ratio values used to quantify the abundance of TiO2 and qualitatively indicate soil maturity. Consistent with previous studies, we find that the moon is 'bluer' at small phase angles, but that the effect on the ratio values for TiO2 abundance for the phase angles of our data is on the order of the measurement uncertainties throughout the range of abundances found in the mare. The effect is more significant as seen from orbiting spacecraft over a range of selenographic latitude. Spectral ratio images (400/560 and 400/730 nm) were used to map the abundance of TiO2 using the empirical relation found by Charlette et al from analysis of returned lunar soils. Additionally, the 950/560 and 950/730 nm image ratios were used to define the regions of mature mare soil in which the relation is valid. Although the phase function dependence on wavelength was investigated and quantified for small areas and the integrated disc, the effect specifically on TiO2 mapping was not rigorously determined. For consistency and convenience in observing the whole lunar front side, our mapping utilized images taken -15 deg less than alpha less than 15 deg when the moon was fully illuminated from earth; however, this includes the strong opposition peak.
Marwani, Hadi M., E-mail: hmarwani@kau.edu.sa [Department of Chemistry, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589 (Saudi Arabia); Center of Excellence for Advanced Materials Research, King Abdulaziz University, P.O. Box 80203, Jeddah 21589 (Saudi Arabia); Asiri, Abdullah M. [Department of Chemistry, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589 (Saudi Arabia); Center of Excellence for Advanced Materials Research, King Abdulaziz University, P.O. Box 80203, Jeddah 21589 (Saudi Arabia); Khan, Salman A. [Department of Chemistry, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589 (Saudi Arabia)
2013-04-15
The main focus of this study was to investigate spectroscopic properties, stoichiometric ratios, physicochemical parameters, polarity and photostability behaviors of newly synthesized chalcone dye in organized media. The chalcone dye, 1-(2,5-Dimethyl-thiophen-3-yl)-3-(9-etnyl-9H-carbazol-3-yl)-propenone (DTEP), was prepared by the reaction of carbazole aldehyde with 3-acetyl-2,5-dimethythiophene. Data obtained from FT-IR, {sup 1}H-–NMR, {sup 13}C-NMR and elemental analysis were consistent with chemical structure of newly prepared DTEP. Increases in fluorescence intensities of DTEP with cetyltrimethyl ammonium bromide (CTAB) were observed. In comparison of fluorescence intensities for DTEP with CTAB, reductions in fluorescence intensities for DTEP with sodium dodecyl sulfate (SDS) were noticed under the same experimental and instrumental conditions. Additionally, Benesi–Hildebrand method was applied to determine stoichiometric ratios and association constants of DTEP with CTAB and SDS. Stern–Volmer plot was used in order to further confirm the stoichiometric ratio and association constant of DTEP with SDS. Physicochemical parameters such as singlet absorption, molar absorptivity, oscillator strength, dipole moment and fluorescence quantum yield of DTEP were also determined. Fluorescence polarity study displayed that DTEP was sensitive to the polarity of the microenvironment provided by different solvents. Finally, fluorescence steady-state measurements revealed that DTEP has high photostability against photobleaching. -- Highlights: ► Mechanistic understanding of molecular structure of newly synthesized chalcone dye. ► Exploring spectral behaviors and physicochemical parameters of chalcone dye. ► Determination of stoichiometric ratios and association constants of chalcone dye. ► Determination of fluorescence quantum yield in different solvents. ► High photostability against photobleaching of chalcone dye was observed.
Experimental spectral analysis of SALMON/STERLING decoupling. Technical report
Blandford, R.R.; Woolson, J.R.
1979-11-30
Re-analysis of SALMON and STERLING initial short-period compressional and surface waves at station PLMS (Poplarville, Mississippi) at a distance of 27 km shows a SALMON/STERLING compressional phase spectral ratio tending to a ratio of only 17 at 25 Hz in agreement with the theoretical caculations of Patterson (1966) and of Healy, King, and 0'Neill (1971). The spectral ratio for the surface waves tends to a ratio of approximately 100 at 25 Hz, in agreement with spectral ratios previously reported by Springer, Denny, Healy, and Mickey (1968), whose data window at PLMS was large enough to consist predominantly of surface waves. The fact that the ratio varies as a function of phase suggests that decoupling varies as a function of takeoff angle, with the least decoupling occurring at high frequencies for the most steeply departing rays. Another topic discussed is the apparent variation in decoupling as defined by the ratio of STERLING/STERLING HE. The variation in this ratio is determined to be explainable by the variation in short point between these two explosions, and not necessarily by a variation in decoupling as a function of azimuth.
Low-Complexity Seizure Prediction From iEEG/sEEG Using Spectral Power and Ratios of Spectral Power.
Zhang, Zisheng; Parhi, Keshab K
2016-06-01
Prediction of seizures is a difficult problem as the EEG patterns are not wide-sense stationary and change from seizure to seizure, electrode to electrode, and from patient to patient. This paper presents a novel patient-specific algorithm for prediction of seizures in epileptic patients from either one or two single-channel or bipolar channel intra-cranial or scalp electroencephalogram (EEG) recordings with low hardware complexity. Spectral power features are extracted and their ratios are computed. For each channel, a total of 44 features including 8 absolute spectral powers, 8 relative spectral powers and 28 spectral power ratios are extracted every two seconds using a 4-second window with a 50% overlap. These features are then ranked and selected in a patient-specific manner using a two-step feature selection. Selected features are further processed by a second-order Kalman filter and then input to a linear support vector machine (SVM) classifier. The algorithm is tested on the intra-cranial EEG (iEEG) from the Freiburg database and scalp EEG (sEEG) from the MIT Physionet database. The Freiburg database contains 80 seizures among 18 patients in 427 hours of recordings. The MIT EEG database contains 78 seizures from 17 children in 647 hours of recordings. It is shown that the proposed algorithm can achieve a sensitivity of 100% and an average false positive rate (FPR) of 0.0324 per hour for the iEEG (Freiburg) database and a sensitivity of 98.68% and an average FPR of 0.0465 per hour for the sEEG (MIT) database. These results are obtained with leave-one-out cross-validation where the seizure being tested is always left out from the training set. The proposed algorithm also has a low complexity as the spectral powers can be computed using FFT. The area and power consumption of the proposed linear SVM are 2 to 3 orders of magnitude less than a radial basis function kernel SVM (RBF-SVM) classifier. Furthermore, the total energy consumption of a system using linear
Augmented Classical Least Squares Multivariate Spectral Analysis
Haaland, David M. (Albuquerque, NM); Melgaard, David K. (Albuquerque, NM)
2005-01-11
A method of multivariate spectral analysis, termed augmented classical least squares (ACLS), provides an improved CLS calibration model when unmodeled sources of spectral variation are contained in a calibration sample set. The ACLS methods use information derived from component or spectral residuals during the CLS calibration to provide an improved calibration-augmented CLS model. The ACLS methods are based on CLS so that they retain the qualitative benefits of CLS, yet they have the flexibility of PLS and other hybrid techniques in that they can define a prediction model even with unmodeled sources of spectral variation that are not explicitly included in the calibration model. The unmodeled sources of spectral variation may be unknown constituents, constituents with unknown concentrations, nonlinear responses, non-uniform and correlated errors, or other sources of spectral variation that are present in the calibration sample spectra. Also, since the various ACLS methods are based on CLS, they can incorporate the new prediction-augmented CLS (PACLS) method of updating the prediction model for new sources of spectral variation contained in the prediction sample set without having to return to the calibration process. The ACLS methods can also be applied to alternating least squares models. The ACLS methods can be applied to all types of multivariate data.
Augmented Classical Least Squares Multivariate Spectral Analysis
Haaland, David M. (Albuquerque, NM); Melgaard, David K. (Albuquerque, NM)
2005-07-26
A method of multivariate spectral analysis, termed augmented classical least squares (ACLS), provides an improved CLS calibration model when unmodeled sources of spectral variation are contained in a calibration sample set. The ACLS methods use information derived from component or spectral residuals during the CLS calibration to provide an improved calibration-augmented CLS model. The ACLS methods are based on CLS so that they retain the qualitative benefits of CLS, yet they have the flexibility of PLS and other hybrid techniques in that they can define a prediction model even with unmodeled sources of spectral variation that are not explicitly included in the calibration model. The unmodeled sources of spectral variation may be unknown constituents, constituents with unknown concentrations, nonlinear responses, non-uniform and correlated errors, or other sources of spectral variation that are present in the calibration sample spectra. Also, since the various ACLS methods are based on CLS, they can incorporate the new prediction-augmented CLS (PACLS) method of updating the prediction model for new sources of spectral variation contained in the prediction sample set without having to return to the calibration process. The ACLS methods can also be applied to alternating least squares models. The ACLS methods can be applied to all types of multivariate data.
Galiana-Merino, J.; Parolai, S.
2005-12-01
The Horizontal-to-Vertical (H/V) spectral ratio of seismic noise has become a widely used tool in microzonation, although it has not yet been clearly established whether or not only the stationary part of the recorded signal may be used. In fact, while some studies have suggested the use of only stationary signals others have shown that including transients may improve the results. In this study, we have employed a filtering method based on the wavelet packet transform for removing the stationary part of the noise recordings in the frequency band of interest for the H/V spectral ratio. In this way, we have obtained filtered seismograms with only transients, which have been used for performing the H/V spectral ratio calculation. Moreover, we have also calculated the H/V spectral ratio selecting only stationary noise windows from the seismograms and without making any a priori selection on them. Finally, we have compared the results and analysed the influence of transient noise on the shape of the H/V spectral ratio. The analysis has been carried out on noise recordings collected at 7 stations installed in the Cologne-Bonn region (Germany). Results show that the H/V spectral ratios calculated using only stationary noise do not significantly differ from those obtained without performing any data selection, independent of the site resonance frequency and of the frequency content of the transient. On the contrary, H/V spectral ratios obtained using only transients show a large variability that may be attributed to the kind of source and the source to receiver distance. These results indicate that the effect of transient noise is negligible when the H/V spectral ratios are calculated without performing any data selection, making the H/V spectral ratio technique more attractive for urban area measurements.
Stationary Time Series Analysis Using Information and Spectral Analysis
1992-09-01
spectral density function of the time series. The spectral density function f(w), 0 < w < 1, is defined as the Fourier transform of...series with spectral density function f(w). 4 An important result of Pinsker [(1964), p. 196] can be interpreted as providing a for- mula for asymptotic...Analysis Papers, Holden-Day, San Francisco, California. Parzen, E. (1958) "On asymptotically efficient consistent estimates of the spectral density function
Digital Forensics Analysis of Spectral Estimation Methods
Mataracioglu, Tolga
2011-01-01
Steganography is the art and science of writing hidden messages in such a way that no one apart from the intended recipient knows of the existence of the message. In today's world, it is widely used in order to secure the information. In this paper, the traditional spectral estimation methods are introduced. The performance analysis of each method is examined by comparing all of the spectral estimation methods. Finally, from utilizing those performance analyses, a brief pros and cons of the spectral estimation methods are given. Also we give a steganography demo by hiding information into a sound signal and manage to pull out the information (i.e, the true frequency of the information signal) from the sound by means of the spectral estimation methods.
Bedform characterization through 2D spectral analysis
Lefebvre, Alice; Ernstsen, Verner Brandbyge; Winter, Christian
2011-01-01
characteristics using twodimensional (2D) spectral analysis is presented and tested on seabed elevation data from the Knudedyb tidal inlet in the Danish Wadden Sea, where large compound bedforms are found. The bathymetric data were divided into 20x20 m areas on which a 2D spectral analysis was applied. The most...... energetic peak of the 2D spectrum was found and its energy, frequency and direction were calculated. A power-law was fitted to the average of slices taken through the 2D spectrum; its slope and y-intercept were calculated. Using these results the test area was morphologically classified into 4 distinct...
Spectral Analysis Code: PARAS SPEC
Chaturvedi, Priyanka; Anandarao, B G
2016-01-01
The light emitted from the stellar photosphere serves as a unique signature for the nature of stars. The behaviour of these stellar lines depend upon the surface temperature, mass, evolutionary status and chemical composition of the star. With the advent of high-resolution spectrographs coupled with medium to large aperture telescopes around the globe, there is plenty of high-resolution and high signal-to-noise ratio data available to the astronomy community. Apart from radial velocity (RV) studies, such data offer us the unique opportunity to study chemical composition and atmospheric properties of the star. The procedure used to derive these parameters must be automated and well adaptable to data available from any high-resolution spectrograph. We hereby present an IDL code, PARAS SPEC, which was primary designed to handle high-resolution spectroscopy data from PARAS spectrograph coupled with the 1.2~m telescope at Mt. Abu, India. This code is designed to adapt with data from other spectrographs as well. Th...
Chandra, Malavika; Scheiman, James; Simeone, Diane; McKenna, Barbara; Purdy, Julianne; Mycek, Mary-Ann
2010-01-01
Pancreatic adenocarcinoma is one of the leading causes of cancer death, in part because of the inability of current diagnostic methods to reliably detect early-stage disease. We present the first assessment of the diagnostic accuracy of algorithms developed for pancreatic tissue classification using data from fiber optic probe-based bimodal optical spectroscopy, a real-time approach that would be compatible with minimally invasive diagnostic procedures for early cancer detection in the pancreas. A total of 96 fluorescence and 96 reflectance spectra are considered from 50 freshly excised tissue sites-including human pancreatic adenocarcinoma, chronic pancreatitis (inflammation), and normal tissues-on nine patients. Classification algorithms using linear discriminant analysis are developed to distinguish among tissues, and leave-one-out cross-validation is employed to assess the classifiers' performance. The spectral areas and ratios classifier (SpARC) algorithm employs a combination of reflectance and fluorescence data and has the best performance, with sensitivity, specificity, negative predictive value, and positive predictive value for correctly identifying adenocarcinoma being 85, 89, 92, and 80%, respectively.
Chandra, Malavika; Scheiman, James; Simeone, Diane; McKenna, Barbara; Purdy, Julianne; Mycek, Mary-Ann
2010-01-01
Pancreatic adenocarcinoma is one of the leading causes of cancer death, in part because of the inability of current diagnostic methods to reliably detect early-stage disease. We present the first assessment of the diagnostic accuracy of algorithms developed for pancreatic tissue classification using data from fiber optic probe-based bimodal optical spectroscopy, a real-time approach that would be compatible with minimally invasive diagnostic procedures for early cancer detection in the pancreas. A total of 96 fluorescence and 96 reflectance spectra are considered from 50 freshly excised tissue sites-including human pancreatic adenocarcinoma, chronic pancreatitis (inflammation), and normal tissues-on nine patients. Classification algorithms using linear discriminant analysis are developed to distinguish among tissues, and leave-one-out cross-validation is employed to assess the classifiers' performance. The spectral areas and ratios classifier (SpARC) algorithm employs a combination of reflectance and fluorescence data and has the best performance, with sensitivity, specificity, negative predictive value, and positive predictive value for correctly identifying adenocarcinoma being 85, 89, 92, and 80%, respectively.
Schael, S.; Barate, R.; Brunelière, R.; Bonis, I. De; Decamp, D.; Goy, C.; Jézéquel, S.; Lees, J.-P.; Martin, F.; Merle, E.; Minard, M.-N.; Pietrzyk, B.; Trocmé, B.; Bravo, S.; Casado, M. P.; Chmeissani, M.; Crespo, J. M.; Fernandez, E.; Fernandez-Bosman, M.; Garrido, Ll.; Martinez, M.; Pacheco, A.; Ruiz, H.; Colaleo, A.; Creanza, D.; Filippis, N. De; Palma, M. De; Iaselli, G.; Maggi, G.; Maggi, M.; Nuzzo, S.; Ranieri, A.; Raso, G.; Ruggieri, F.; Selvaggi, G.; Silvestris, L.; Tempesta, P.; Tricomi, A.; Zito, G.; Huang, X.; Lin, J.; Ouyang, Q.; Wang, T.; Xie, Y.; Xu, R.; Xue, S.; Zhang, J.; Zhang, L.; Zhao, W.; Abbaneo, D.; Barklow, T.; Buchmüller, O.; Cattaneo, M.; Clerbaux, B.; Drevermann, H.; Forty, R. W.; Frank, M.; Gianotti, F.; Hansen, J. B.; Harvey, J.; Hutchcroft, D. E.; Janot, P.; Jost, B.; Kado, M.; Mato, P.; Moutoussi, A.; Ranjard, F.; Rolandi, L.; Schlatter, D.; Teubert, F.; Valassi, A.; Videau, I.; Badaud, F.; Dessagne, S.; Falvard, A.; Fayolle, D.; Gay, P.; Jousset, J.; Michel, B.; Monteil, S.; Pallin, D.; Pascolo, J. M.; Perret, P.; Hansen, J. D.; Hansen, J. R.; Hansen, P. H.; Kraan, A. C.; Nilsson, B. S.; Kyriakis, A.; Markou, C.; Simopoulou, E.; Vayaki, A.; Zachariadou, K.; Blondel, A.; Brient, J.-C.; Machefert, F.; Rougé, A.; Videau, H.; Ciulli, V.; Focardi, E.; Parrini, G.; Antonelli, A.; Antonelli, M.; Bencivenni, G.; Bossi, F.; Capon, G.; Cerutti, F.; Chiarella, V.; Laurelli, P.; Mannocchi, G.; Murtas, G. P.; Passalacqua, L.; Kennedy, J.; Lynch, J. G.; Negus, P.; O'Shea, V.; Thompson, A. S.; Wasserbaech, S.; Cavanaugh, R.; Dhamotharan, S.; Geweniger, C.; Hanke, P.; Hepp, V.; Kluge, E. E.; Putzer, A.; Stenzel, H.; Tittel, K.; Wunsch, M.; Beuselinck, R.; Cameron, W.; Davies, G.; Dornan, P. J.; Girone, M.; Marinelli, N.; Nowell, J.; Rutherford, S. A.; Sedgbeer, J. K.; Thompson, J. C.; White, R.; Ghete, V. M.; Girtler, P.; Kneringer, E.; Kuhn, D.; Rudolph, G.; Bouhova-Thacker, E.; Bowdery, C. K.; Clarke, D. P.; Ellis, G.; Finch, A. J.; Foster, F.; Hughes, G.; Jones, R. W. L.; Pearson, M. R.; Robertson, N. A.; Smizanska, M.; van der Aa, O.; Delaere, C.; Leibenguth, G.; Lemaitre, V.; Blumenschein, U.; Hölldorfer, F.; Jakobs, K.; Kayser, F.; Müller, A.-S.; Renk, B.; Sander, H.-G.; Schmeling, S.; Wachsmuth, H.; Zeitnitz, C.; Ziegler, T.; Bonissent, A.; Coyle, P.; Curtil, C.; Ealet, A.; Fouchez, D.; Payre, P.; Tilquin, A.; Ragusa, F.; David, A.; Dietl, H.; Ganis, G.; Hüttmann, K.; Lütjens, G.; Männer, W.; Moser, H.-G.; Settles, R.; Villegas, M.; Wolf, G.; Boucrot, J.; Callot, O.; Davier, M.; Duflot, L.; Grivaz, J.-F.; Heusse, Ph.; Höcker, A.; Jacholkowska, A.; Serin, L.; Veillet, J.-J.; Yuan, C. Z.; Zhang, Z. Q.; Azzurri, P.; Bagliesi, G.; Boccali, T.; Foà, L.; Giammanco, A.; Giassi, A.; Ligabue, F.; Messineo, A.; Palla, F.; Sanguinetti, G.; Sciabà, A.; Sguazzoni, G.; Spagnolo, P.; Tenchini, R.; Venturi, A.; Verdini, P. G.; Awunor, O.; Blair, G. A.; Cowan, G.; Garcia-Bellido, A.; Green, M. G.; Medcalf, T.; Misiejuk, A.; Strong, J. A.; Teixeira-Dias, P.; Clifft, R. W.; Edgecock, T. R.; Norton, P. R.; Tomalin, I. R.; Ward, J. J.; Bloch-Devaux, B.; Boumediene, D.; Colas, P.; Fabbro, B.; Lançon, E.; Lemaire, M.-C.; Locci, E.; Perez, P.; Rander, J.; Tuchming, B.; Vallage, B.; Litke, A. M.; Taylor, G.; Booth, C. N.; Cartwright, S.; Combley, F.; Hodgson, P. N.; Lehto, M.; Thompson, L. F.; Böhrer, A.; Brandt, S.; Grupen, C.; Hess, J.; Ngac, A.; Prange, G.; Borean, C.; Giannini, G.; He, H.; Putz, J.; Rothberg, J.; Armstrong, S. R.; Berkelman, K.; Cranmer, K.; Ferguson, D. P. S.; Gao, Y.; González, S.; Hayes, O. J.; Hu, H.; Jin, S.; Kile, J.; McNamara, P. A., III; Nielsen, J.; Pan, Y. B.; von Wimmersperg-Toeller, J. H.; Wiedenmann, W.; Wu, J.; Lan Wu, Sau; Wu, X.; Zobernig, G.; Dissertori, G.; Aleph Collaboration
2005-12-01
The full LEP-1 data set collected with the ALEPH detector at the Z pole during 1991-1995 is analysed in order to measure the τ decay branching fractions. The analysis follows the global method used in the published study based on 1991-1993 data, but several improvements are introduced, especially concerning the treatment of photons and π0's. Extensive systematic studies are performed, in order to match the large statistics of the data sample corresponding to over 300 000 measured and identified τ decays. Branching fractions are obtained for the two leptonic channels and 11 hadronic channels defined by their respective numbers of charged particles and π0's. Using previously published ALEPH results on final states with charged and neutral kaons, corrections are applied to the hadronic channels to derive branching ratios for exclusive final states without kaons. Thus the analyses of the full LEP-1 ALEPH data are combined to yield a complete description of τ decays, encompassing 22 non-strange and 11 strange hadronic modes. Some physics implications of the results are given, in particular related to universality in the leptonic charged weak current, isospin invariance in a1 decays, and the separation of vector and axial-vector components of the total hadronic rate. Finally, spectral functions are determined for the dominant hadronic modes and updates are given for several analyses. These include: tests of isospin invariance between the weak charged and electromagnetic hadronic currents, fits of the ρ resonance lineshape, and a QCD analysis of the non-strange hadronic decays using spectral moments, yielding the value αs(mτ2)=0.340±0.005exp±0.014th. The evolution to the Z mass scale yields αs(MZ2)=0.1209±0.0018. This value agrees well with the direct determination from the Z width and provides the most accurate test to date of asymptotic freedom in the QCD gauge theory.
Comparison between two methods for forward calculation of ambient noise H/V spectral ratios
Garcia-Jerez, A.; Luzón, F.; Sanchez-Sesma, F. J.; Santoyo, M. A.; Albarello, D.; Lunedei, E.; Campillo, M.; Iturrarán-Viveros, U.
2011-12-01
The analysis of horizontal-to-vertical spectral ratios of ambient noise (NHVSR) is a valuable tool for seismic prospecting, particularly if both a dense spatial sampling and a low-cost procedure are required. Unfortunately, the computation method still lacks of a unanimously accepted theoretical basis and different approaches are currently being used for inversion of the ground structure from the measured H/V curves. Two major approaches for forward calculation of NHVSRs in a layered medium are compared in this work. The first one was developed by Arai and Tokimatsu (2004) and recently improved by Albarello and Lunedei (2011). It consists of a description of the wavefield as generated by Far Surface point Forces (FSF method). The second one is based on the work of Sánchez-Sesma et al. (2011) who consider ambient noise as a Diffuse WaveField (DWF method), taking advantage of the proportionality between its Fourier-transformed autocorrelation (power spectrum) and the imaginary part of the Green function when source and receiver are the same. In both methods, the NHVSR is written as (PH/PV)1/2, where PH and PV are the horizontal and vertical power spectra. In the FSF method these quantities are given by PV∝⊙m(1+1/2χm2α2)(ARm/kRm)2 PH∝⊙m{(1+1/2χm2α2)(ARm/kRm)2χm2+1/2α2(ALm/kLm)2} where kRm, χm and ARm are wavenumber, ellipticity and medium response of the m-th Rayleigh wave mode; kLm and ALm correspond to the m-th Love wave mode and α is the horizontal-to-vertical load ratio of the ambient noise sources. Some common factors are omitted in the expressions of PV and PH. On the other hand, the DWF method deals with the full wavefield including both surface and body waves. In order to make the comparison easier, and taking into account that surface waves are often the dominant components in wide spectral ranges, body wave contributions are neglected here. In this case, the PH and PV power spectra for the DWF method are reduced to the simple expressions: PV
[Comparison of two spectral mixture analysis models].
Wang, Qin-Jun; Lin, Qi-Zhong; Li, Ming-Xiao; Wang, Li-Ming
2009-10-01
A spectral mixture analysis experiment was designed to compare the spectral unmixing effects of linear spectral mixture analysis (LSMA) and constraint linear spectral mixture analysis (CLSMA). In the experiment, red, green, blue and yellow colors were printed on a coarse album as four end members. Thirty nine mixed samples were made according to each end member's different percent in one pixel. Then, field spectrometer was located on the top of the mixed samples' center to measure spectrum one by one. Inversion percent of each end member in the pixel was extracted using LSMA and CLSMA models. Finally, normalized mean squared error was calculated between inversion and real percent to compare the two models' effects on spectral unmixing. Results from experiment showed that the total error of LSMA was 0.30087 and that of CLSMA was 0.37552 when using all bands in the spectrum. Therefore, LSMA was 0.075 less than that of CLSMA when the whole bands of four end members' spectra were used. On the other hand, the total error of LSMA was 0.28095 and that of CLSMA was 0.29805 after band selection. So, LSMA was 0.017 less than that of CLSMA when bands selection was performed. Therefore, whether all or selected bands were used, the accuracy of LSMA was better than that of CLSMA because during the process of spectrum measurement, errors caused by instrument or human were introduced into the model, leading to that the measured data could not mean the strict requirement of CLSMA and therefore reduced its accuracy: Furthermore, the total error of LSMA using selected bands was 0.02 less than that using the whole bands. The total error of CLSMA using selected bands was 0.077 less than that using the whole bands. So, in the same model, spectral unmixing using selected bands to reduce the correlation of end members' spectra was superior to that using the whole bands.
SpecViz: Interactive Spectral Data Analysis
Earl, Nicholas Michael; STScI
2016-06-01
The astronomical community is about to enter a new generation of scientific enterprise. With next-generation instrumentation and advanced capabilities, the need has arisen to equip astronomers with the necessary tools to deal with large, multi-faceted data. The Space Telescope Science Institute has initiated a data analysis forum for the creation, development, and maintenance of software tools for the interpretation of these new data sets. SpecViz is a spectral 1-D interactive visualization and analysis application built with Python in an open source development environment. A user-friendly GUI allows for a fast, interactive approach to spectral analysis. SpecViz supports handling of unique and instrument-specific data, incorporation of advanced spectral unit handling and conversions in a flexible, high-performance interactive plotting environment. Active spectral feature analysis is possible through interactive measurement and statistical tools. It can be used to build wide-band SEDs, with the capability of combining or overplotting data products from various instruments. SpecViz sports advanced toolsets for filtering and detrending spectral lines; identifying, isolating, and manipulating spectral features; as well as utilizing spectral templates for renormalizing data in an interactive way. SpecViz also includes a flexible model fitting toolset that allows for multi-component models, as well as custom models, to be used with various fitting and decomposition routines. SpecViz also features robust extension via custom data loaders and connection to the central communication system underneath the interface for more advanced control. Incorporation with Jupyter notebooks via connection with the active iPython kernel allows for SpecViz to be used in addition to a user’s normal workflow without demanding the user drastically alter their method of data analysis. In addition, SpecViz allows the interactive analysis of multi-object spectroscopy in the same straight
SPAM- SPECTRAL ANALYSIS MANAGER (DEC VAX/VMS VERSION)
Solomon, J. E.
1994-01-01
The Spectral Analysis Manager (SPAM) was developed to allow easy qualitative analysis of multi-dimensional imaging spectrometer data. Imaging spectrometers provide sufficient spectral sampling to define unique spectral signatures on a per pixel basis. Thus direct material identification becomes possible for geologic studies. SPAM provides a variety of capabilities for carrying out interactive analysis of the massive and complex datasets associated with multispectral remote sensing observations. In addition to normal image processing functions, SPAM provides multiple levels of on-line help, a flexible command interpretation, graceful error recovery, and a program structure which can be implemented in a variety of environments. SPAM was designed to be visually oriented and user friendly with the liberal employment of graphics for rapid and efficient exploratory analysis of imaging spectrometry data. SPAM provides functions to enable arithmetic manipulations of the data, such as normalization, linear mixing, band ratio discrimination, and low-pass filtering. SPAM can be used to examine the spectra of an individual pixel or the average spectra over a number of pixels. SPAM also supports image segmentation, fast spectral signature matching, spectral library usage, mixture analysis, and feature extraction. High speed spectral signature matching is performed by using a binary spectral encoding algorithm to separate and identify mineral components present in the scene. The same binary encoding allows automatic spectral clustering. Spectral data may be entered from a digitizing tablet, stored in a user library, compared to the master library containing mineral standards, and then displayed as a timesequence spectral movie. The output plots, histograms, and stretched histograms produced by SPAM can be sent to a lineprinter, stored as separate RGB disk files, or sent to a Quick Color Recorder. SPAM is written in C for interactive execution and is available for two different
LASER SPECTRAL ANALYSIS OF STRAIN MEASUREM ENT
姜耀东; 陈至达
1994-01-01
Modern optical theory has shown that the far field or Fraunhofer diffraction equipment is identical to the Fourier spectral analyzer. In the Fourier spectral analyzer the Fourier spectra or the Fraunhofer diffraction pattern of a graph is formed on the back foeal plane when a laser beam is directed on the graph lying on the front focal plane； the Fourier spectra of the graph is also subjected to change during the deformation of the graph. Through analyzing the change of Fourier spectra the deformation of the graph can be obtained. A few years ago, based on the above principles the authors proposed a new technique of strain measurement by laser spectral analysis. Demonstration and discussion will be made in detail in this paper.
Spectral theory and nonlinear functional analysis
Lopez-Gomez, Julian
2001-01-01
This Research Note addresses several pivotal problems in spectral theory and nonlinear functional analysis in connection with the analysis of the structure of the set of zeroes of a general class of nonlinear operators. It features the construction of an optimal algebraic/analytic invariant for calculating the Leray-Schauder degree, new methods for solving nonlinear equations in Banach spaces, and general properties of components of solutions sets presented with minimal use of topological tools. The author also gives several applications of the abstract theory to reaction diffusion equations and systems.The results presented cover a thirty-year period and include recent, unpublished findings of the author and his coworkers. Appealing to a broad audience, Spectral Theory and Nonlinear Functional Analysis contains many important contributions to linear algebra, linear and nonlinear functional analysis, and topology and opens the door for further advances.
SVD analysis of Aura TES spectral residuals
Beer, Reinhard; Kulawik, Susan S.; Rodgers, Clive D.; Bowman, Kevin W.
2005-01-01
Singular Value Decomposition (SVD) analysis is both a powerful diagnostic tool and an effective method of noise filtering. We present the results of an SVD analysis of an ensemble of spectral residuals acquired in September 2004 from a 16-orbit Aura Tropospheric Emission Spectrometer (TES) Global Survey and compare them to alternative methods such as zonal averages. In particular, the technique highlights issues such as the orbital variation of instrument response and incompletely modeled effects of surface emissivity and atmospheric composition.
Spectral deconvolution and operational use of stripping ratios in airborne radiometrics.
Allyson, J D; Sanderson, D C
2001-01-01
Spectral deconvolution using stripping ratios for a set of pre-defined energy windows is the simplest means of reducing the most important part of gamma-ray spectral information. In this way, the effective interferences between the measured peaks are removed, leading, through a calibration, to clear estimates of radionuclide inventory. While laboratory measurements of stripping ratios are relatively easy to acquire, with detectors placed above small-scale calibration pads of known radionuclide concentrations, the extrapolation to measurements at altitudes where airborne survey detectors are used bring difficulties such as air-path attenuation and greater uncertainties in knowing ground level inventories. Stripping ratios are altitude dependent, and laboratory measurements using various absorbers to simulate the air-path have been used with some success. Full-scale measurements from an aircraft require a suitable location where radionuclide concentrations vary little over the field of view of the detector (which may be hundreds of metres). Monte Carlo simulations offer the potential of full-scale reproduction of gamma-ray transport and detection mechanisms. Investigations have been made to evaluate stripping ratios using experimental and Monte Carlo methods.
Spectral ratio techniques as a tool for soil-structure interaction assessment
Ladina, C.; Lovati, S.; Marzorati, S.; Massa, M.
2009-04-01
structure, is built on lithological units characterized by alluvial deposits. All noise measurements, characterized by a minimum duration of 30 minutes (sampling rate 100 Hz), were performed using a Lennartz LE3D-5s seismometer (flat response 0.2 - 40 Hz) coupled with a 24 bits Reftek 130/01 digital recorder. To investigate the dynamic characterization of buildings both standard spectral ratio (SSR) and horizontal to vertical spectral ratio (HVNR) techniques were applied to the recorded data; in the first case two simultaneous measures, computed at the bottom and at the top of the structure were considered. For the stations where earthquakes recordings were available, the results from ambients noise were compared, to those obtained from earthquakes (HVSR). For all records the linear trend and the instrumental response were removed and a band-pass Butterworth 4 poles filter between 0.2 and 25 Hz was applied. Then each component of noise was windowed in time series of 120 s length (cosine taper 5%), the horizontal components were rotated between 0° and 175° with step of 5° and the power spectral density (PSD) were calculated using a Konno and Ohmachi (1998) window (b=20). Finally, for each considered azimuth average HVNRs were computed calculating for each time window the spectral ratio between the spectrum of the radial component over the spectrum of the vertical one. For earthquake the data processing were performed as described for noise but considering different portion of signal: 5 s and 15 s of S waves, starting 0.5 s before the S-waves picking, and 20 s of coda were selected. Also in this case for each selected window HVSR were calculated through a directional analysis as that described for HVNR. The results highlight the fundamental role of the installation. For BAG8 and AUL, where the sensors are directly installed on rock, the vibrations of the structure do not affect HVNR at the bottom, which show flat responses in the whole frequency range: in both cases the
Ratio Analysis: Where Investments Meet Mathematics.
Barton, Susan D.; Woodbury, Denise
2002-01-01
Discusses ratio analysis by which investments may be evaluated. Requires the use of fundamental mathematics, problem solving, and a comparison of the mathematical results within the framework of industry. (Author/NB)
Large tensor-to-scalar ratio and running of the scalar spectral index with Instep Inflation
Ballesteros, Guillermo
2014-01-01
If a sizeable tensor-to-scalar ratio ~0.1 turns out to be detected and a negative running of the scalar spectral index ~0.01 is significantly required by the data, the vast majority of single field models of inflation will be ruled out. We show that a flat tree-level effective potential, lifted by radiative corrections and by the imprints of a high energy scale (in the form of non-renormalizable operators) can explain those features and produce enough inflation in the slow-roll regime.
Kano, Y.; Tadokoro, K.; Nishigami, K.; Mori, J.
2006-12-01
We measured the seismic attenuation of the rock mass surrounding the Nojima fault, Japan, by estimating the P-wave quality factor, Qp, using spectral ratios derived from a multi-depth (800 m and 1800 m) seismometer array. We detected an increase of Qp in 2003-2006 compared to 1999-2000. Following the 1995 Kobe earthquake, the project "Fault Zone Probe" drilled three boreholes to depths of 500 m, 800 m, 1800 m, in Toshima, along the southern part of the Nojima fault. The 1800-m borehole was reported to reach the fault surface. One seismometer (TOS1) was installed at the bottom of the 800-m borehole in 1996 and another (TOS2) at the bottom of 1800-m borehole in 1997. The sampling rate of the seismometers is 100 Hz. The slope of the spectral ratios for the two stations plotted on a linear-log plot is -π t^{*}, where t^{*} is the travel time divided by the Qp for the path difference between the stations. For the estimation of Qp, we used events recorded by both TOS1 and TOS2 for periods of 1999-2000 and 2003-2006. To improve the signal-to-noise ratio of the spectral ratios, we first calculated spectra ratios between TOS1 and TOS2 for each event and averaged the values over the earthquakes for each period. We used the events that occurred within 10 km from TOS2, and the numbers of events are 74 for 1999-2000 and 105 for 2003-2006. Magnitudes of the events range from M0.5 to M3.1. The average value of Qp for 1999-2000 increased significantly compared to 2003-2006. The attenuation of rock mass surrounding the fault in 2003-2006 is smaller than that in 1999-2000, which suggests that the fault zone became stiffer after the earthquake. At the Nojima fault, permeability measured by repeated pumping tests decreased with time from the Kobe earthquake, infering the closure of cracks and a fault healing process occurred The increase of Qp is another piece of evidence for the healing process of the Nojima fault zone. u.ac.jp/~kano/
Exoplanetary Detection By Multifractal Spectral Analysis
Agarwal, Sahil; Wettlaufer, John S
2016-01-01
Owing to technological advances the number of exoplanets discovered has risen dramatically in the last few years. However, when trying to observe Earth analogs, it is often difficult to test the veracity of detection. We have developed a new approach to the analysis of exoplanetary spectral observations based on temporal multifractality, which identifies time scales that characterize planetary orbital motion around the host star. Without fitting spectral data to stellar models, we show how the planetary signal can be robustly detected from noisy data using noise amplitude as a source of information. For observation of transiting planets, combining this method with simple geometry allows us to relate the time scales obtained to primary transit and secondary exoplanet eclipse of the exoplanets. Making use of data obtained with ground-based and space-based observations we have tested our approach on HD 189733b. Moreover, we have investigated the use of this technique in measuring planetary orbital motion via dop...
Jorge Alfredo Ardila-Rey
2014-02-01
Full Text Available Partial discharge (PD detection is a standardized technique to qualify electrical insulation in machines and power cables. Several techniques that analyze the waveform of the pulses have been proposed to discriminate noise from PD activity. Among them, spectral power ratio representation shows great flexibility in the separation of the sources of PD. Mapping spectral power ratios in two-dimensional plots leads to clusters of points which group pulses with similar characteristics. The position in the map depends on the nature of the partial discharge, the setup and the frequency response of the sensors. If these clusters are clearly separated, the subsequent task of identifying the source of the discharge is straightforward so the distance between clusters can be a figure of merit to suggest the best option for PD recognition. In this paper, two inductive sensors with different frequency responses to pulsed signals, a high frequency current transformer and an inductive loop sensor, are analyzed to test their performance in detecting and separating the sources of partial discharges.
Reginato, R. J.; Vedder, J. F.; Idso, S. B.; Jackson, R. D.; Blanchard, M. B.; Goettelman, R.
1977-01-01
For several days in March of 1975, reflected solar radiation measurements were obtained from smooth and rough surfaces of wet, drying, and continually dry Avondale loam at Phoenix, Arizona, with pyranometers located 50 cm above the ground surface and a multispectral scanner flown at a 300-m height. The simple summation of the different band radiances measured by the multispectral scanner proved equally as good as the pyranometer data for estimating surface soil water content if the multispectral scanner data were standardized with respect to the intensity of incoming solar radiation or the reflected radiance from a reference surface, such as the continually dry soil. Without this means of standardization, multispectral scanner data are most useful in a spectral band ratioing context. Our results indicated that, for the bands used, no significant information on soil water content could be obtained by band ratioing. Thus the variability in soil water content should insignificantly affect soil-type discrimination based on identification of type-specific spectral signatures. Therefore remote sensing, conducted in the 0.4- to 1.0-micron wavelength region of the solar spectrum, would seem to be much More suited to identifying crop and soil types than to estimating of soil water content.
Banas, Krzysztof; Banas, Agnieszka M; Heussler, Sascha P; Breese, Mark B H
2018-01-05
In the contemporary spectroscopy there is a trend to record spectra with the highest possible spectral resolution. This is clearly justified if the spectral features in the spectrum are very narrow (for example infra-red spectra of gas samples). However there is a plethora of samples (in the liquid and especially in the solid form) where there is a natural spectral peak broadening due to collisions and proximity predominately. Additionally there is a number of portable devices (spectrometers) with inherently restricted spectral resolution, spectral range or both, which are extremely useful in some field applications (archaeology, agriculture, food industry, cultural heritage, forensic science). In this paper the investigation of the influence of spectral resolution, spectral range and signal-to-noise ratio on the identification of high explosive substances by applying multivariate statistical methods on the Fourier transform infra-red spectral data sets is studied. All mathematical procedures on spectral data for dimension reduction, clustering and validation were implemented within R open source environment. Copyright © 2017 Elsevier B.V. All rights reserved.
Fereidouni, F.; Bader, A.N.; Gerritsen, H.C.
2012-01-01
A new global analysis algorithm to analyse (hyper-) spectral images is presented. It is based on the phasor representation that has been demonstrated to be very powerful for the analysis of lifetime imaging data. In spectral phasor analysis the fluorescence spectrum of each pixel in the image is Fou
Spectral Analysis of Nonstationary Spacecraft Vibration Data
1965-11-01
the instantaneous power spectral density function for the process (y(t)). This spectral function can take on negative values for certain cases...power spectral density function is not directly measurable in the frequency domain. An experimental estimate for the function can be obtained only by...called the generalized power spectral density function for the process (y(t)) . This spectral description for nonstationary data is of great value for
a Brief Climatology of Cirrus LIDAR Ratios Measured by High Spectral Resolution LIDAR
Kuehn, R.; Holz, R.; Hair, J. W.; Vaughan, M. A.; Eloranta, E. W.
2015-12-01
Our ability to detect and probe the vertical extent of cirrus was hugely improved with the launch of the NASA-CNES CALIPSO mission in April 2006. However, our skill at retrieving the optical properties of the cirrus detected by the CALIPSO lidar is not yet commensurate with our detection abilities. As with any new observing system, CALIPSO faces challenges and uncertainties in the retrieval of the geophysical parameters from its fundamental measurements. Specifically, extinction and optical depth retrievals for elastic backscatter lidars like CALIPSO typically rely on a priori assumptions about layer-mean extinction-to-backscatter ratios (AKA lidar ratios), which can vary regionally and for which uncertainties are high. To improve CALIPSO optical properties retrievals, we show High Spectral Resolution Lidar (HSRL) measurements acquired with systems from the University of Wisconsin and NASA Langley. HSRLs can directly determine ice cloud extinction and lidar ratio by separately measuring the molecular and particulate components of the total backscattered signal, thus largely eliminating many of the uncertainties inherent in elastic backscatter retrievals. These measurements were acquired during the SEAC4RS (Huntsville, AL, USA and Singapore), and FRAPPE/DISCOVER-AQ 2014 (BAO tower near Boulder, CO, USA) field campaigns, and an intensive operations period in Hampton, VA, USA.
Spectral analysis of allogeneic hydroxyapatite powders
Timchenko, P. E.; Timchenko, E. V.; Pisareva, E. V.; Vlasov, M. Yu; Red’kin, N. A.; Frolov, O. O.
2017-01-01
In this paper we discuss the application of Raman spectroscopy to the in vitro analysis of the hydroxyapatite powder samples produced from different types of animal bone tissue during demineralization process at various acid concentrations and exposure durations. The derivation of the Raman spectrum of hydroxyapatite is attempted by the analysis of the pure powders of its known constituents. Were experimentally found spectral features of hydroxyapatite, based on analysis of the line amplitude at wave numbers 950-965 cm-1 ((PO4)3- (ν1) vibration) and 1065-1075 cm-1 ((CO3)2-(ν1) B-type replacement). Control of physicochemical properties of hydroxyapatite was carried out by Raman spectroscopy. Research results are compared with an infrared Fourier spectroscopy.
Global Source Parameters from Regional Spectral Ratios for Yield Transportability Studies
Phillips, W. S.; Fisk, M. D.; Stead, R. J.; Begnaud, M. L.; Rowe, C. A.
2016-12-01
We use source parameters such as moment, corner frequency and high frequency rolloff as constraints in amplitude tomography, ensuring that spectra of well-studied earthquakes are recovered using the ensuing attenuation and site term model. We correct explosion data for path and site effects using such models, which allows us to test transportability of yield estimation techniques based on our best source spectral estimates. To develop a background set of source parameters, we applied spectral ratio techniques to envelopes of a global set of regional distance recordings from over 180,000 crustal events. Corner frequencies and moment ratios were determined via inversion using all event pairs within predetermined clusters, shifting to absolute levels using independently determined regional and teleseismic moments. The moment and corner frequency results can be expressed as stress drop, which has considerable scatter, yet shows dramatic regional patterns. We observe high stress in subduction zones along S. America, S. Mexico, the Banda Sea, and associated with the Yakutat Block in Alaska. We also observe high stress at the Himalayan syntaxes, the Pamirs, eastern Iran, the Caspian, the Altai-Sayan, and the central African rift. Low stress is observed along mid ocean spreading centers, the Afar rift, patches of convergence zones such as Nicaragua, the Zagros, Tibet, and the Tien Shan, among others. Mine blasts appear as low stress events due to their low corners and steep rolloffs. Many of these anomalies have been noted by previous studies, and we plan to compare results directly. As mentioned, these results will be used to constrain tomographic imaging, but can also be used in model validation procedures similar to the use of ground truth in location problems, and, perhaps most importantly, figure heavily in quality control of local and regional distance amplitude measurements.
Multivariate Analysis of Solar Spectral Irradiance Measurements
Pilewskie, P.; Rabbette, M.
2001-01-01
Principal component analysis is used to characterize approximately 7000 downwelling solar irradiance spectra retrieved at the Southern Great Plains site during an Atmospheric Radiation Measurement (ARM) shortwave intensive operating period. This analysis technique has proven to be very effective in reducing a large set of variables into a much smaller set of independent variables while retaining the information content. It is used to determine the minimum number of parameters necessary to characterize atmospheric spectral irradiance or the dimensionality of atmospheric variability. It was found that well over 99% of the spectral information was contained in the first six mutually orthogonal linear combinations of the observed variables (flux at various wavelengths). Rotation of the principal components was effective in separating various components by their independent physical influences. The majority of the variability in the downwelling solar irradiance (380-1000 nm) was explained by the following fundamental atmospheric parameters (in order of their importance): cloud scattering, water vapor absorption, molecular scattering, and ozone absorption. In contrast to what has been proposed as a resolution to a clear-sky absorption anomaly, no unexpected gaseous absorption signature was found in any of the significant components.
Spectral analysis of signals the missing data case
Wang, Yanwei
2006-01-01
Spectral estimation is important in many fields including astronomy, meteorology, seismology, communications, economics, speech analysis, medical imaging, radar, sonar, and underwater acoustics. Most existing spectral estimation algorithms are devised for uniformly sampled complete-data sequences. However, the spectral estimation for data sequences with missing samples is also important in many applications ranging from astronomical time series analysis to synthetic aperture radar imaging with angular diversity. For spectral estimation in the missing-data case, the challenge is how to extend t
Least Squares Moving-Window Spectral Analysis.
Lee, Young Jong
2017-01-01
Least squares regression is proposed as a moving-windows method for analysis of a series of spectra acquired as a function of external perturbation. The least squares moving-window (LSMW) method can be considered an extended form of the Savitzky-Golay differentiation for nonuniform perturbation spacing. LSMW is characterized in terms of moving-window size, perturbation spacing type, and intensity noise. Simulation results from LSMW are compared with results from other numerical differentiation methods, such as single-interval differentiation, autocorrelation moving-window, and perturbation correlation moving-window methods. It is demonstrated that this simple LSMW method can be useful for quantitative analysis of nonuniformly spaced spectral data with high frequency noise.
Structural Vibration Monitoring Using Cumulative Spectral Analysis
Satoru Goto
2013-01-01
Full Text Available This paper describes a resonance decay estimation for structural health monitoring in the presence of nonstationary vibrations. In structural health monitoring, the structure's frequency response and resonant decay characteristics are very important for understanding how the structure changes. Cumulative spectral analysis (CSA estimates the frequency decay by using the impulse response. However, measuring the impulse response of buildings is impractical due to the need to shake the building itself. In a previous study, we reported on system damping monitoring using cumulative harmonic analysis (CHA, which is based on CSA. The current study describes scale model experiments on estimating the hidden resonance decay under non-stationary noise conditions by using CSA for structural condition monitoring.
Spectral luminescence analysis of amniotic fluid
Slobozhanina, Ekaterina I.; Kozlova, Nataly M.; Kasko, Leonid P.; Mamontova, Marina V.; Chernitsky, Eugene A.
1997-12-01
It is shown that the amniotic fluid has intensive ultra-violet luminescence caused by proteins. Along with it amniotic fluid radiated in the field of 380 - 650 nm with maxima at 430 - 450 nm and 520 - 560 nm. The first peak of luminescence ((lambda) exc equals 350 nm; (lambda) em equals 430 - 440 nm) is caused (most probably) by the presence in amniotic fluid of some hormones, NADH2 and NADPH2. A more long-wave component ((lambda) exc equals 460 nm; (lambda) em equals 520 - 560 nm) is most likely connected with the presence in amniotic fluid pigments (bilirubin connected with protein and other). It is shown that intensity and maximum of ultra-violet luminescence spectra of amniotic fluid in normality and at pathology are identical. However both emission spectra and excitation spectra of long-wave ((lambda) greater than 450 nm) luminescence of amniotic fluid from pregnant women with such prenatal abnormal developments of a fetus as anencephaly and spina bifida are too long-wave region in comparison with the norm. Results of research testify that spectral luminescent analysis of amniotic fluid can be used for screening of malformations of the neural tube. It is very difficult for a practical obstetrician to reveal pregnant women with a high risk of congenital malformations of the fetus. Apart from ultrasonic examination, cytogenetic examination of amniotic fluid and defumination of concentrations of alpha-fetoprotein and acetylcholin-esterases in the amniotic fluid and blood plasma are the most widely used diagnostic approaches. However, biochemical and cytogenetic diagnostic methods are time-consuming. In the present work spectral luminescence properties of the amniotic fluid are investigated to determine spectral parameters that can be used to reveal pregnant women with a high risk of congenital malformations of their offsprings.
Spectral efficiency analysis of OCDMA systems
Hui Yan; Kun Qiu; Yun Ling
2009-01-01
We discuss several kinds of code schemes and analyze their spectral efficiency, code utilizing efficiency, and the maximal spectral efficiency. Error correction coding is used to increase the spectral efficiency, and it can avoid the spectral decrease with the increase of the length. The extended primer code (EPC) has the highest spectral efficiency in the unipolar code system. The bipolar code system has larger spectral efficiency than unipolar code system, but has lower code utilizing efficiency and the maximal spectral efficiency. From the numerical results, we can see that the spectral efficiency increases by 0.025 (b/s)/Hz when the bit error rate (BER) increases from 10-9 to 10-7.
Spectral analysis of snoring events from an Emfit mattress.
Perez-Macias, Jose Maria; Viik, Jari; Varri, Alpo; Himanen, Sari-Leena; Tenhunen, Mirja
2016-12-01
The aim of this study is to explore the capability of an Emfit (electromechanical film transducer) mattress to detect snoring (SN) by analyzing the spectral differences between normal breathing (NB) and SN. Episodes of representative NB and SN of a maximum of 10 min were visually selected for analysis from 33 subjects. To define the bands of interest, we studied the statistical differences in the power spectral density (PSD) between both breathing types. Three bands were selected for further analysis: 6-16 Hz (BW1), 16-30 Hz (BW2) and 60-100 Hz (BW3). We characterized the differences between NB and SN periods in these bands using a set of spectral features estimated from the PSD. We found that 15 out of the 29 features reached statistical significance with the Mann-Whitney U-test. Diagnostic properties for each feature were assessed using receiver operating characteristic analysis. According to our results, the highest diagnostic performance was achieved using the power ratio between BW2 and BW3 (0.85 area under the receiver operating curve, 80% sensitivity, 80% specificity and 80% accuracy). We found that there are significant differences in the defined bands between the NB and SN periods. A peak was found in BW3 for SN epochs, which was best detected using power ratios. Our work suggests that it is possible to detect snoring with an Emfit mattress. The mattress-type movement sensors are inexpensive and unobtrusive, and thus provide an interesting tool for sleep research.
Spectral analysis on graph-like spaces
Post, Olaf
2012-01-01
Small-radius tubular structures have attracted considerable attention in the last few years, and are frequently used in different areas such as Mathematical Physics, Spectral Geometry and Global Analysis. In this monograph, we analyse Laplace-like operators on thin tubular structures ("graph-like spaces''), and their natural limits on metric graphs. In particular, we explore norm resolvent convergence, convergence of the spectra and resonances. Since the underlying spaces in the thin radius limit change, and become singular in the limit, we develop new tools such as -norm convergence of operators acting in different Hilbert spaces, - an extension of the concept of boundary triples to partial differential operators, and -an abstract definition of resonances via boundary triples. These tools are formulated in an abstract framework, independent of the original problem of graph-like spaces, so that they can be applied in many other situations where the spaces are perturbed.
Spectral analysis and filter theory in applied geophysics
Buttkus, Burkhard
2000-01-01
This book is intended to be an introduction to the fundamentals and methods of spectral analysis and filter theory and their appli cations in geophysics. The principles and theoretical basis of the various methods are described, their efficiency and effectiveness eval uated, and instructions provided for their practical application. Be sides the conventional methods, newer methods arediscussed, such as the spectral analysis ofrandom processes by fitting models to the ob served data, maximum-entropy spectral analysis and maximum-like lihood spectral analysis, the Wiener and Kalman filtering methods, homomorphic deconvolution, and adaptive methods for nonstation ary processes. Multidimensional spectral analysis and filtering, as well as multichannel filters, are given extensive treatment. The book provides a survey of the state-of-the-art of spectral analysis and fil ter theory. The importance and possibilities ofspectral analysis and filter theory in geophysics for data acquisition, processing an...
Huang, Jyun Yan; Wen, Kuo Liang; Te Chen, Chun; Chang, Shun Chiang
2014-05-01
Taipei city is the capital of Taiwan which located in Taipei basin and covered with hundreds meter of alluvial layer that might cause serious damage during huge earthquake. Prediction of possible strong motion levels occurred in the basin then became popular. Engineers most like to use Ground Motion Prediction Equation (GMPEs) as common tool for seismic hazard calculation but GMPEs were usually debated that it can only give one prediction value (PGA, PGV, Sa etc.) rather than time history or spectrum. Seismologists tried theoretical simulation (1D, 2D, 3D method) but could only give low frequency (usually less than 1 Hz) results restricted to that the shallow structures were not clear enough. Resent years, wide frequency simulation techniques such as empirical green's function added stochastic simulation method (hybrid method) were applied to several different purposes but site effect still plays an important role that need to be considered. Traditionally soil to rock spectral ratio of shear wave (denoted as S/R) was widely applied to check basin effect for decades but the technique needs lots of permanent stations and several years to get enough records. If some site located within strong motion network but not close enough to the strong motion stations, interpolate or extrapolate results needed to be used. Wen and Huang (2012) conducted a dense microtremor measurement network in whole Taiwan and applied microtremor H/V to discuss dominant frequency with traditional transfer functions from earthquake shear wave and found good agreement between them. Furthermore, in this study, the ability of soil to rock spectral ratio of microtremor (denoted as MS/R) measurement was tested in Taipei basin. The preliminary results showed MS/R had good agreement with S/R between 0.2 to 5 Hz. And distance from soil site to reference rock site should no greater than 8 to 10 km base on degree of spectrum difference (DSPD) calculation. If the MS/R works that site effect study from this
Lobos, Gustavo A.; Poblete-Echeverría, Carlos
2017-01-01
This article describes public, free software that provides efficient exploratory analysis of high-resolution spectral reflectance data. Spectral reflectance data can suffer from problems such as poor signal to noise ratios in various wavebands or invalid measurements due to changes in incoming solar radiation or operator fatigue leading to poor orientation of sensors. Thus, exploratory data analysis is essential to identify appropriate data for further analyses. This software overcomes the problem that analysis tools such as Excel are cumbersome to use for the high number of wavelengths and samples typically acquired in these studies. The software, Spectral Knowledge (SK-UTALCA), was initially developed for plant breeding, but it is also suitable for other studies such as precision agriculture, crop protection, ecophysiology plant nutrition, and soil fertility. Various spectral reflectance indices (SRIs) are often used to relate crop characteristics to spectral data and the software is loaded with 255 SRIs which can be applied quickly to the data. This article describes the architecture and functions of SK-UTALCA and the features of the data that led to the development of each of its modules. PMID:28119705
Partial discharge source recognition by means of clustering of spectral power ratios
Martínez-Tarifa, J. M.; Ardila-Rey, J. A.; Robles, G.
2013-12-01
Partial discharge (PD) detection can give useful information for the diagnosis of electrical apparatus, but data interpretation can be impossible if several sources are simultaneously active. Pulse characterization can be used to identify the source origin in PD measurements. The distribution of energy at different frequencies helps in distinguishing several types of discharges. The parameterization of pulses by means of spectral power ratios (PR) has been studied as a reliable technique to represent different characteristics in high-frequency current pulses in high-voltage tests. In this study, the separation of PD sources by means of PR maps is proposed. This approach has proven to be effective in the identification of PD sources when two electrical insulation systems are simultaneously subjected to discharge activity in controlled experiments where internal, surface and corona discharges were occurring. The flexibility of the system to improve cluster separation is shown, and measurements are also made on a real insulated power cable, where two simultaneous PD sources were successfully identified.
Applications methods of spectral ratios in the estimation of site effects: Case Damien (Haiti)
Jean, B. J.; ST Fleur, S.
2014-12-01
Measurements of H/V type were carried out on the Damien site with Tromino hardware an « all in one » station which includes both the sensor and the integrated digitizer. A total of 32 measurements of seismic noise have been completed on this site in order to see if lithological site effects are detectable with this H/V method. After checking the H/V curve reliability criteria (length of the window to be analyzed, the number of windows analyzed, standard deviation) and the criteria for clear peaks in H/V (conditions for the amplitude, conditions for stability) found in the SESAME project in 2004, the results of the H/V spectra obtained are generally very consistent and clearly indicate site effects with peak resonance frequencies between 3 and 14 Hz. The presence of these well defined frequency peaks in the H/V spectral ratio indicates that the ground motion can be amplified by geomorphological site effects. Comparative analyzes of these H/V measurements with Grilla and Geopsy software were made in this paper to estimate the amplification magnitude of these effects. Graphical comparisons between the Grilla and Geopsy H/V maps were completed in this study and allow us to identify typical areas and their associated fundamental resonance frequencies.
Detection of water molecules in inert gas based plasma by the ratios of atomic spectral lines
Bernatskiy, A. V.; Ochkin, V. N.
2017-01-01
A new approach is considered to detect the water leaks in inert plasma-forming gas present in the reactor chamber. It is made up of the intensity ratio of D α and H α spectral lines in combination with O, Ar and Xe lines intensity. The concentrations of H2O, O, H and D particles have been measured with high sensitivity. At the D2 admixture pressure {{p}{{\\text{D}\\text{2}}}} = 0.025 mbar, we used the acquisition time of 10 s to measure the rate of water molecules injected from the outside, Γ0 = 1.4 · 10-9 mbar · m3 · s-1, and the incoming water molecules to plasma, Γ = 5 ·10-11 mbar · m3 · s-1. The scaling proves that at small D2 admixtures (10-4 mbar), the leaks with the rates Γ0 ≈ 6 · 10-12 mbar · m3 · s-1 and Γ ≈ 2 · 10-13 mbar · m3 · s-1 can be detected and measured. The difference between Γ0 and Γ values is due to the high degree of H2O dissociation, which can be up to 97-98%.
Seasonal changes in H/V spectral ratio at high-latitude seismic stations
Lee, R. F.; Abbott, R. E.; Knox, H. A.; Pancha, A.
2014-12-01
We present results demonstrating seasonal variations in the Horizontal-to-Vertical Spectral Ratio (HVSR) at high-latitude seismic stations. We analyze data from two sites at Poker Flat Research Range, near Fairbanks, Alaska. From the first site, we analyze 3 stations installed by Sandia National Labs (SNL) in a valley with marshy summer conditions. We also analyze the PASSCAL Instrument Center station PIC2, which is installed on rock approximately 3.2 km from the SNL stations. These stations continuously record data at 125 (SNL) and 200 (PIC2) samples per second. Seasonal changes in HVSR at high frequencies (> 20 Hz) appear to be caused by impedance contrasts between frozen and thawed ground. Thawed active layers are known to have slower shear-wave velocities than frozen layers or bedrock. An estimate of active layer thickness at each station is obtained from the quarter-wavelength approximation. We verify the accuracy of this technique by obtaining ground-truth measurements at the sites for both thickness and shear-wave velocity. We use physical probing for the thickness measurements and active-source Refraction-Microtremor (ReMi) surveys for the shear-wave velocities. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000
Digital spectral analysis parametric, non-parametric and advanced methods
Castanié, Francis
2013-01-01
Digital Spectral Analysis provides a single source that offers complete coverage of the spectral analysis domain. This self-contained work includes details on advanced topics that are usually presented in scattered sources throughout the literature.The theoretical principles necessary for the understanding of spectral analysis are discussed in the first four chapters: fundamentals, digital signal processing, estimation in spectral analysis, and time-series models.An entire chapter is devoted to the non-parametric methods most widely used in industry.High resolution methods a
Phase Spectral Analysis of EEG Signals
YOURong-yi; CHENZhong
2004-01-01
A new method of phase spectral analysis of EEG is proposed for the comparative analysis of phase spectra between normal EEG and epileptic EEG signals based on the wavelet decomposition technique. By using multiscale wavelet decomposition, the original EEGs are mapped to an orthogonal wavelet space, such that the variations of phase can be observed at multiscale. It is found that the phase (and phase difference) spectra of normal EEGs are distinct from that of epileptic EEGs. That is the variations of phase (and phase difference) of normal EEGs have a distinct periodic pattern with the electrical activity proceeds in the brain, but do not the epileptic EEGs. For epileptic EEGs, only at those transient points, the phase variations are obvious. In order to verify these results with the observational data, the phase variations of EEGs in principal component space are observed and found that, the features of phase spectra is in correspondence with that the wavelet space. These results make it possible to view the behavior of EEG rhythms as a dynamic spectrum.
Spectral analysis of individual realization LDA data
Tummers, M.J.; Passchier, D.M.
1998-01-01
The estimation of the autocorrelation function (act) or the spectral density function (sdt) from LDA data poses unique data-processing problems. The random sampling times in LDA preclude the use of the spectral methods for equi-spaced samples. As a consequence, special data-processing algorithms are
Partial spectral analysis of hydrological time series
Jukić, D.; Denić-Jukić, V.
2011-03-01
SummaryHydrological time series comprise the influences of numerous processes involved in the transfer of water in hydrological cycle. It implies that an ambiguity with respect to the processes encoded in spectral and cross-spectral density functions exists. Previous studies have not paid attention adequately to this issue. Spectral and cross-spectral density functions represent the Fourier transforms of auto-covariance and cross-covariance functions. Using this basic property, the ambiguity is resolved by applying a novel approach based on the spectral representation of partial correlation. Mathematical background for partial spectral density, partial amplitude and partial phase functions is presented. The proposed functions yield the estimates of spectral density, amplitude and phase that are not affected by a controlling process. If an input-output relation is the subject of interest, antecedent and subsequent influences of the controlling process can be distinguished considering the input event as a referent point. The method is used for analyses of the relations between the rainfall, air temperature and relative humidity, as well as the influences of air temperature and relative humidity on the discharge from karst spring. Time series are collected in the catchment of the Jadro Spring located in the Dinaric karst area of Croatia.
Photometric Redshift Estimation Using Spectral Connectivity Analysis
Freeman, P E; Lee, A B; Richards, J W; Schafer, C M
2009-01-01
The development of fast and accurate methods of photometric redshift estimation is a vital step towards being able to fully utilize the data of next-generation surveys within precision cosmology. In this paper we apply a specific approach to spectral connectivity analysis (SCA; Lee & Wasserman 2009) called diffusion map. SCA is a class of non-linear techniques for transforming observed data (e.g., photometric colours for each galaxy, where the data lie on a complex subset of p-dimensional space) to a simpler, more natural coordinate system wherein we apply regression to make redshift predictions. As SCA relies upon eigen-decomposition, our training set size is limited to ~ 10,000 galaxies; we use the Nystrom extension to quickly estimate diffusion coordinates for objects not in the training set. We apply our method to 350,738 SDSS main sample galaxies, 29,816 SDSS luminous red galaxies, and 5,223 galaxies from DEEP2 with CFHTLS ugriz photometry. For all three datasets, we achieve prediction accuracies on ...
Michael L Turnbull
2008-11-01
An alternative seismic shaking vulnerability survey method to computational intensive theoretical modelling of site response to earthquake, and time consuming test versus reference site horizontal ratio methods, is described. The methodology is suitable for small to large scale engineering investigations. Relative seismic shaking vulnerability microzonation using an adaptation of the Nakamura horizontal to vertical spectral ratio method provides many advantages over alternative methods including: low cost; rapid field phase (100 km2 can easily be covered by a single operator in 5 days); low and flexible instrumentation requirements (a single seismometer and data logger of almost any type is required); field data can be collected at any time during the day or night (the results are insensitive to ambient social noise); no basement rock reference site is required (thus eliminating trigger synchronisation between reference and multiple test site seismographs); rapid software aided analysis; insensitivity to ground-shaking resonance peaks; ability to compare results obtained from non-contiguous survey fields. The methodology is described in detail, and a practical case study is provided, including mapped results. The resulting microzonation maps indicate the relative seismic shaking vulnerability for built structures of different height categories within adjacent zones, with a resolution of approximately 1 km.
The Microtremor H/V Spectral Ratio: The Physical Basis of the Diffuse Field Assumption
Sanchez-Sesma, F. J.
2016-12-01
The microtremor H/V spectral ratio (MHVSR) is popular to obtain the dominant frequency at a site. Despite the success of MHVSR some controversy arose regarding its physical basis. One approach is the Diffuse Field Assumption, DFA. It is then assumed that noise diffuse features come from multiple scattering within the medium. According to theory, the average of the autocorrelation is proportional to directional energy density (DED) and to the imaginary part of the Green's function for same source and receiver. Then, the square of MHVSR is a ratio of DEDs which, in a horizontally layered system, is 2xImG11/ImG33, where ImG11 and ImG33 are the imaginary parts of Green's functions for horizontal and vertical components. This has physical implications that emerge from the duality DED-force, implicit in the DFA. Consider a surface force at a half-space. The radiated energy is carried away by various wave types and the proportions of each one are precisely the fractions of the energy densities of a diffuse elastic wave field at the free surface. Thus, some properties of applied forces are also characteristics of DEDs. For example, consider a Poisson solid. For a normal point load, 67 per cent of energy is carried away by Rayleigh waves. For the tangential case, it is less well known that, 77 per cent of energy goes as shear waves. In a full space, 92 per cent of the energy is emitted as shear waves. The horizontal DED at the half-space surface implies significant emission of down-going shear waves that explains the curious stair-like resonance spectrum of ImG11. Both ImG11 and ImG33 grow linearly versus frequency and this represents wave emission. For a layered medium, besides wave emission, the ensuing variations correspond to reflected waves. For high frequencies, ImG33 depends on the properties of the top layer. Reflected body waves are very small and Rayleigh waves behave in the top layer as in a kind of mini half-space. From HVSR one can invert the velocity model
Mapping a part of Neuquen Basin in Argentina by global-phase H/V spectral ratio
Nishitsuji, Y.; Ruigrok, E.; Gomez, M.; Draganov, D.S.
2015-01-01
We investigated the applicability of global phases (epicentral distances of ≥ 120° and ≥ 150°) for the H/V spectral ratio to identify the fundamental resonance frequency. We applied the method to delineate a part of Neuquén basin in Argentina without the need for active seismic sources. We obtained
Factor Analysis for Spectral Reconnaissance and Situational Understanding
2016-07-11
reviewed journals: Final Report: Factor Analysis for Spectral Reconnaissance and Situational Understanding Report Title The Army has a critical need for...based NP-hard design problems, by associating them with corresponding estimation problems. 1 Factor Analysis for Spectral Reconnaissance and Situational ...SECURITY CLASSIFICATION OF: The Army has a critical need for enhancing situational understanding for dismounted soldiers and rapidly deployed tactical
Elgass, Kirstin; Zell, Martina; Maurino, Veronica G.; Schleifenbaum, Frank
2011-02-01
Leaf cells of living plants exhibit strong fluorescence from chloroplasts, the reaction centers of photosynthesis. Mutations in the photosystems change their structure and can, thus, be monitored by recording the fluorescence spectra of the emitted chlorophyll light. These measurements have, up to now, mostly been carried out at low temperatures (77 K), as these conditions enable the differentiation between the fluorescence of Photosystem I (PSI) and Photosystem II (PSII). In contrast, at room temperature, energy transfer processes between the various photosynthetic complexes result in very similar fluorescence emissions, which mainly consist of fluorescence photons emitted by PSII hindering a discrimination based on spectral ROIs (regions of interest). However, by statistical analysis of high resolution fluorescence spectra recorded at room temperature, it is possible to draw conclusions about the relative PSI/PSII ratio. Here, the possibility of determining the relative PSI/PSII ratio by fluorescence spectroscopy is demonstrated in living maize plants. Bundle-sheath chloroplasts of mature maize plants have a special morphologic characteristic; they are agranal, or exhibit only rudimentary grana, respectively. These chloroplasts are depleted in PSII activity and it could be shown that PSII is progressively reduced during leaf differentiation. A direct comparison of PSII activity in isolated chloroplasts is nearly impossible, since the activity of PSII in both mesophyll- and bundle-sheath chloroplasts decays with time after isolation and it takes significantly longer to isolate bundle-sheath chloroplasts. Considering this fact the measurement of PSI/PSII ratios with the 77K method, which includes taking fluorescence spectra from a diluted suspension of isolated chloroplasts at 77K, is questionable. These spectra are then used to analyze the distribution of energy between PSI and PSII. After rapid cooling to 77K secondary biochemical influences, which attenuate the
Spectral Efficiency Analysis for Multicarrier Based 4G Systems
Silva, Nuno; Rahman, Muhammad Imadur; Frederiksen, Flemming Bjerge;
2006-01-01
In this paper, a spectral efficiency definition is proposed. Spectral efficiency for multicarrier based multiaccess techniques, such as OFDMA, MC-CDMA and OFDMA-CDM, is analyzed. Simulations for different indoor and outdoor scenarios are carried out. Based on the simulations, we have discussed ho...... different wireless channel’s condition affects the performance of a system in terms of spectral efficiency. Based on our analysis, we have also recommended different access techniques for different scenarios....
LIU Liang-yun; HUANG Wen-jiang; PU Rui-liang; WANG Ji-hua
2014-01-01
Spectral relfectance in the near-infrared (NIR) shoulder (750-900 nm) region is affected by internal leaf structure, but it has rarely been investigated. In this study, a dehydration treatment and three paraquat herbicide applications were conducted to explore how spectral relfectance and shape in the NIR shoulder region responded to various stresses. A new spectral ratio index in the NIR shoulder region (NSRI), deifned by a simple ratio of relfectance at 890 nm to relfectance at 780 nm, was proposed for assessing leaf structure deterioration. Firstly, a wavelength-independent increase in spectral relfectance in the NIR shoulder region was observed from the mature leaves with slight dehydration. An increase in spectral slope in the NIR shoulder would be expected only when water stress developed sufifciently to cause severe leaf dehydration resulting in an alteration in cell structure. Secondly, the alteration of leaf cell structure caused by Paraquat herbicide applications resulted in a wavelength-dependent variation of spectral relfectance in the NIR shoulder region. The NSRI in the NIR shoulder region increased signiifcantly under an herbicide application. Although the dehydration process also occurred with the herbicide injury, NSRI is more sensitive to herbicide injury than the water-related indices (water index and normalized difference water index) and normalized difference vegetation index. Finally, the sensitivity of NSRI to stripe rust in winter wheat was examined, yielding a determination coefifcient of 0.61, which is more signiifcant than normalized difference vegetation index (NDVI), water index (WI) and normalized difference water index (NDWI), with a determination coefifcient of 0.45, 0.36 and 0.13, respectively. In this study, all experimental results demonstrated that NSRI will increase with internal leaf structure deterioration, and it is also a sensitive spectral index for herbicide injury or stripe rust in winter wheat.
Krina, Anastasia; Koutsias, Nikos
2016-04-01
The proportion of unburned vegetation within a fire affected area can be regarded as a proxy measure of fire severity that can be estimated by means of remote sensing techniques. Yet, in order to obtain sound results, it is essential to improve our current knowledge regarding the spectral discrimination of areas that have been completely burnt from adjacent areas within a fire perimeter that still have patches of vegetation, or unburned proportion of vegetation on them. The aim of our research is to reveal the role of the vegetation or the small vegetation gaps in spectral characteristics of pixels with mixed land cover synthesis (burned, vegetation and soil) to achieve a better assessment of fire mapping and the impact of fire in the burned area. Three land cover types were identified, namely vegetation, bare land and burned area by applying pixel based classification using the maximum likelihood algorithm in high-resolution aerial photographs (1m). Moreover, multispectral satellite Landsat data that were acquired close to capture date of the aerial photos and were converted to TOC reflectance from USGS, were used to measure the association between land cover portions and satellite-derived VIs and spectral signatures. A grid of 30x30m was created to extract the ratio of the land cover categories corresponding to each selected pixel of the satellite image LANDSAT TM. Samples of different land cover ratios and of different types of substrate (e.g. rocks, light- or dark-colored soil) were delineated and their reflectance values at each spectral channel were extracted and used to calculate statistics in order to characterize the spectral properties. Finally, various vegetation indices were computed to investigate the role of the proportion of land cover and substrate in the variation of VIs. The results of our study reveal the spectral characteristics of burnt area at the pixel level and suggest the efficiency of certain spectral channels for the estimation of the
Spectral signature verification using statistical analysis and text mining
DeCoster, Mallory E.; Firpi, Alexe H.; Jacobs, Samantha K.; Cone, Shelli R.; Tzeng, Nigel H.; Rodriguez, Benjamin M.
2016-05-01
In the spectral science community, numerous spectral signatures are stored in databases representative of many sample materials collected from a variety of spectrometers and spectroscopists. Due to the variety and variability of the spectra that comprise many spectral databases, it is necessary to establish a metric for validating the quality of spectral signatures. This has been an area of great discussion and debate in the spectral science community. This paper discusses a method that independently validates two different aspects of a spectral signature to arrive at a final qualitative assessment; the textual meta-data and numerical spectral data. Results associated with the spectral data stored in the Signature Database1 (SigDB) are proposed. The numerical data comprising a sample material's spectrum is validated based on statistical properties derived from an ideal population set. The quality of the test spectrum is ranked based on a spectral angle mapper (SAM) comparison to the mean spectrum derived from the population set. Additionally, the contextual data of a test spectrum is qualitatively analyzed using lexical analysis text mining. This technique analyzes to understand the syntax of the meta-data to provide local learning patterns and trends within the spectral data, indicative of the test spectrum's quality. Text mining applications have successfully been implemented for security2 (text encryption/decryption), biomedical3 , and marketing4 applications. The text mining lexical analysis algorithm is trained on the meta-data patterns of a subset of high and low quality spectra, in order to have a model to apply to the entire SigDB data set. The statistical and textual methods combine to assess the quality of a test spectrum existing in a database without the need of an expert user. This method has been compared to other validation methods accepted by the spectral science community, and has provided promising results when a baseline spectral signature is
Temporal shape analysis via the spectral signature.
Bernardis, Elena; Konukoglu, Ender; Ou, Yangming; Metaxas, Dimitris N; Desjardins, Benoit; Pohl, Kilian M
2012-01-01
In this paper, we adapt spectral signatures for capturing morphological changes over time. Advanced techniques for capturing temporal shape changes frequently rely on first registering the sequence of shapes and then analyzing the corresponding set of high dimensional deformation maps. Instead, we propose a simple encoding motivated by the observation that small shape deformations lead to minor refinements in the spectral signature composed of the eigenvalues of the Laplace operator. The proposed encoding does not require registration, since spectral signatures are invariant to pose changes. We apply our representation to the shapes of the ventricles extracted from 22 cine MR scans of healthy controls and Tetralogy of Fallot patients. We then measure the accuracy score of our encoding by training a linear classifier, which outperforms the same classifier based on volumetric measurements.
Boscolo, Sonia; Fatome, Julien; Finot, Christophe
2017-04-01
We numerically study the effects of amplitude fluctuations and signal-to-noise ratio degradation of the seed pulses on the spectral compression process arising from nonlinear propagation in an optical fibre. The unveiled quite good stability of the process against these pulse degradation factors is assessed in the context of optical regeneration of intensity-modulated signals, by combining nonlinear spectral compression with centered bandpass optical filtering. The results show that the proposed nonlinear processing scheme indeed achieves mitigation of the signal's amplitude noise. However, in the presence of a jitter of the temporal duration of the pulses, the performance of the device deteriorates. © 2016 Elsevier
Advanced spectral analysis of ionospheric waves observed with sparse arrays
Helmboldt, J. F.; Intema, H. T.
2014-02-01
This paper presents a case study from a single, 6h observing period to illustrate the application of techniques developed for interferometric radio telescopes to the spectral analysis of observations of ionospheric fluctuations with sparse arrays. We have adapted the deconvolution methods used for making high dynamic range images of cosmic sources with radio arrays to making comparably high dynamic range maps of spectral power of wavelike ionospheric phenomena. In the example presented here, we have used observations of the total electron content (TEC) gradient derived from Very Large Array (VLA) observations of synchrotron emission from two galaxy clusters at 330MHz as well as GPS-based TEC measurements from a sparse array of 33 receivers located within New Mexico near the VLA. We show that these techniques provide a significant improvement in signal-to-noise ratio (S/N) of detected wavelike structures by correcting for both measurement inaccuracies and wavefront distortions. This is especially true for the GPS data when combining all available satellite/receiver pairs, which probe a larger physical area and likely have a wider variety of measurement errors than in the single-satellite case. In this instance, we found that the peak S/N of the detected waves was improved by more than an order of magnitude. The data products generated by the deconvolution procedure also allow for a reconstruction of the fluctuations as a two-dimensional waveform/phase screen that can be used to correct for their effects.
Spectral Analysis of Rich Network Topology in Social Networks
Wu, Leting
2013-01-01
Social networks have received much attention these days. Researchers have developed different methods to study the structure and characteristics of the network topology. Our focus is on spectral analysis of the adjacency matrix of the underlying network. Recent work showed good properties in the adjacency spectral space but there are few…
Visual category recognition using Spectral Regression and Kernel Discriminant Analysis
Tahir, M.A.; Kittler, J.; Mikolajczyk, K.; Yan, F.; van de Sande, K.E.A.; Gevers, T.
2009-01-01
Visual category recognition (VCR) is one of the most important tasks in image and video indexing. Spectral methods have recently emerged as a powerful tool for dimensionality reduction and manifold learning. Recently, Spectral Regression combined with Kernel Discriminant Analysis (SR-KDA) has been s
Spectral Analysis of Rich Network Topology in Social Networks
Wu, Leting
2013-01-01
Social networks have received much attention these days. Researchers have developed different methods to study the structure and characteristics of the network topology. Our focus is on spectral analysis of the adjacency matrix of the underlying network. Recent work showed good properties in the adjacency spectral space but there are few…
On the Australian Bank Financial Ratio Analysis
张丽娜
2011-01-01
Financial ratios,despite some criticisms,are still used as a basis to evaluate a firm's performance,to make credit risk assessment decisions and classify firms into bankrupt and non-bankrupt groups.There are a great number of financial ratios which can be used for the evaluation of banks performance.Golin (2001) provides a list of over 80 ratios covering the major categories of capital,asset quality,profitability & efficiency,and liquidity & funding provides.
Nonlinear physical systems spectral analysis, stability and bifurcations
Kirillov, Oleg N
2013-01-01
Bringing together 18 chapters written by leading experts in dynamical systems, operator theory, partial differential equations, and solid and fluid mechanics, this book presents state-of-the-art approaches to a wide spectrum of new and challenging stability problems.Nonlinear Physical Systems: Spectral Analysis, Stability and Bifurcations focuses on problems of spectral analysis, stability and bifurcations arising in the nonlinear partial differential equations of modern physics. Bifurcations and stability of solitary waves, geometrical optics stability analysis in hydro- and magnetohydrodynam
Corporate prediction models, ratios or regression analysis?
Bijnen, E.J.; Wijn, M.F.C.M.
1994-01-01
The models developed in the literature with respect to the prediction of a company s failure are based on ratios. It has been shown before that these models should be rejected on theoretical grounds. Our study of industrial companies in the Netherlands shows that the ratios which are used in
Spectral Synthesis via Mean Field approach Independent Component Analysis
Hu, Ning; Kong, Xu
2015-01-01
In this paper, we apply a new statistical analysis technique, Mean Field approach to Bayesian Independent Component Analysis (MF-ICA), on galaxy spectral analysis. This algorithm can compress the stellar spectral library into a few Independent Components (ICs), and galaxy spectrum can be reconstructed by these ICs. Comparing to other algorithms which decompose a galaxy spectrum into a combination of several simple stellar populations, MF-ICA approach offers a large improvement in the efficiency. To check the reliability of this spectral analysis method, three different methods are used: (1) parameter-recover for simulated galaxies, (2) comparison with parameters estimated by other methods, and (3) consistency test of parameters from the Sloan Digital Sky Survey galaxies. We find that our MF-ICA method not only can fit the observed galaxy spectra efficiently, but also can recover the physical parameters of galaxies accurately. We also apply our spectral analysis method to the DEEP2 spectroscopic data, and find...
Spatially explicit spectral analysis of point clouds and geospatial data
Buscombe, Daniel
2016-01-01
The increasing use of spatially explicit analyses of high-resolution spatially distributed data (imagery and point clouds) for the purposes of characterising spatial heterogeneity in geophysical phenomena necessitates the development of custom analytical and computational tools. In recent years, such analyses have become the basis of, for example, automated texture characterisation and segmentation, roughness and grain size calculation, and feature detection and classification, from a variety of data types. In this work, much use has been made of statistical descriptors of localised spatial variations in amplitude variance (roughness), however the horizontal scale (wavelength) and spacing of roughness elements is rarely considered. This is despite the fact that the ratio of characteristic vertical to horizontal scales is not constant and can yield important information about physical scaling relationships. Spectral analysis is a hitherto under-utilised but powerful means to acquire statistical information about relevant amplitude and wavelength scales, simultaneously and with computational efficiency. Further, quantifying spatially distributed data in the frequency domain lends itself to the development of stochastic models for probing the underlying mechanisms which govern the spatial distribution of geological and geophysical phenomena. The software package PySESA (Python program for Spatially Explicit Spectral Analysis) has been developed for generic analyses of spatially distributed data in both the spatial and frequency domains. Developed predominantly in Python, it accesses libraries written in Cython and C++ for efficiency. It is open source and modular, therefore readily incorporated into, and combined with, other data analysis tools and frameworks with particular utility for supporting research in the fields of geomorphology, geophysics, hydrography, photogrammetry and remote sensing. The analytical and computational structure of the toolbox is described
Spatially explicit spectral analysis of point clouds and geospatial data
Buscombe, Daniel D.
2015-01-01
The increasing use of spatially explicit analyses of high-resolution spatially distributed data (imagery and point clouds) for the purposes of characterising spatial heterogeneity in geophysical phenomena necessitates the development of custom analytical and computational tools. In recent years, such analyses have become the basis of, for example, automated texture characterisation and segmentation, roughness and grain size calculation, and feature detection and classification, from a variety of data types. In this work, much use has been made of statistical descriptors of localised spatial variations in amplitude variance (roughness), however the horizontal scale (wavelength) and spacing of roughness elements is rarely considered. This is despite the fact that the ratio of characteristic vertical to horizontal scales is not constant and can yield important information about physical scaling relationships. Spectral analysis is a hitherto under-utilised but powerful means to acquire statistical information about relevant amplitude and wavelength scales, simultaneously and with computational efficiency. Further, quantifying spatially distributed data in the frequency domain lends itself to the development of stochastic models for probing the underlying mechanisms which govern the spatial distribution of geological and geophysical phenomena. The software packagePySESA (Python program for Spatially Explicit Spectral Analysis) has been developed for generic analyses of spatially distributed data in both the spatial and frequency domains. Developed predominantly in Python, it accesses libraries written in Cython and C++ for efficiency. It is open source and modular, therefore readily incorporated into, and combined with, other data analysis tools and frameworks with particular utility for supporting research in the fields of geomorphology, geophysics, hydrography, photogrammetry and remote sensing. The analytical and computational structure of the toolbox is
Accuracy analysis of a spectral Poisson solver
Rambaldi, S. [Dipartimento di Fisica Universita di Bologna and INFN, Bologna, Via Irnerio 46, 40126 (Italy)]. E-mail: rambaldi@bo.infn.it; Turchetti, G. [Dipartimento di Fisica Universita di Bologna and INFN, Bologna, Via Irnerio 46, 40126 (Italy); Benedetti, C. [Dipartimento di Fisica Universita di Bologna and INFN, Bologna, Via Irnerio 46, 40126 (Italy); Mattioli, F. [Dipartimento di Fisica Universita di Bologna, Bologna, Via Irnerio 46, 40126 (Italy); Franchi, A. [GSI, Darmstadt, Planckstr. 1, 64291 (Germany)
2006-06-01
We solve Poisson's equation in d=2,3 space dimensions by using a spectral method based on Fourier decomposition. The choice of the basis implies that Dirichlet boundary conditions on a box are satisfied. A Green's function-based procedure allows us to impose Dirichlet conditions on any smooth closed boundary, by doubling the computational complexity. The error introduced by the spectral truncation and the discretization of the charge distribution is evaluated by comparison with the exact solution, known in the case of elliptical symmetry. To this end boundary conditions on an equipotential ellipse (ellipsoid) are imposed on the numerical solution. Scaling laws for the error dependence on the number K of Fourier components for each space dimension and the number N of point charges used to simulate the charge distribution are presented and tested. A procedure to increase the accuracy of the method in the beam core region is briefly outlined.
Methods of Spectral Analysis in C++ (MOSAIC)
Engesser, Michael
2016-06-01
Stellar spectroscopic classification is most often still done by hand. MOSAIC is a project focused on the collection and classification of astronomical spectra using a computerized algorithm. The code itself attempts to accurately classify stellar spectra according to the broad spectral classes within the Morgan-Keenan system of spectral classification, based on estimated temperature and the relative abundances of certain notable elements (Hydrogen, Helium, etc.) in the stellar atmosphere. The methodology includes calibrating the wavelength for pixels across the image by using the wavelength dispersion of pixels inherent with the spectrograph used. It then calculates the location of the peak in the star's Planck spectrum in order to roughly classify the star. Fitting the graph to a blackbody curve is the final step for a correct classification. Future work will involve taking a closer look at emission lines and luminosity classes.
Artifacts Of Spectral Analysis Of Instrument Readings
Wise, James H.
1995-01-01
Report presents experimental and theoretical study of some of artifacts introduced by processing outputs of two nominally identical low-frequency-reading instruments; high-sensitivity servo-accelerometers mounted together and operating, in conjunction with signal-conditioning circuits, as seismometers. Processing involved analog-to-digital conversion with anti-aliasing filtering, followed by digital processing including frequency weighting and computation of different measures of power spectral density (PSD).
Isotope ratio analysis by Orbitrap mass spectrometry
Eiler, J. M.; Chimiak, L. M.; Dallas, B.; Griep-Raming, J.; Juchelka, D.; Makarov, A.; Schwieters, J. B.
2016-12-01
Several technologies are being developed to examine the intramolecular isotopic structures of molecules (i.e., site-specific and multiple substitution), but various limitations in sample size and type or (for IRMS) resolution have so far prevented the creation of a truly general technique. We will discuss the initial findings of a technique based on Fourier transform mass spectrometry, using the Thermo Scientific Q Exactive GC — an instrument that contains an Orbitrap mass analyzer. Fourier transform mass spectrometry is marked by exceptionally high mass resolutions (the Orbitrap reaches M/∆M in the range 250,000-1M in the mass range of greatest interest, 50-200 amu). This allows for resolution of a large range of nearly isobaric interferences for isotopologues of volatile and semi-volatile compounds (i.e., involving isotopes of H, C, N, O and S). It also provides potential to solve very challenging mass resolution problems for isotopic analysis of other, heavier elements. Both internal and external experimental reproducibilities of isotope ratio analyses using the Orbitrap typically conform to shot-noise limits down to levels of 0.2 ‰ (1SE), and routinely in the range 0.5-1.0 ‰, with similar accuracy when standardized to concurrently run reference materials. Such measurements can be made without modifications to the ion optics of the Q Exactive GC, but do require specially designed sample introduction devices to permit sample/standard comparison and long integration times. The sensitivity of the Q Exactive GC permits analysis of sub-nanomolar samples and quantification of multiply-substituted species. The site-specific capability of this instrument arises from the fact that mass spectra of molecular analytes commonly contain diverse fragment ion species, each of which samples a specific sub-set of molecular sites. We will present applications of this technique to the biological and abiological chemistry of amino acids, forensic identification of
Sanchez-Sesma, F. J.; Piña, J.; Campillo, M.; Luzón, F.; García-Jerez, A.; Albarello, D.; Lunedei, E.
2012-12-01
The seismic ambient noise horizontal-to-vertical spectral ratios (NHVSR) are valuable for microzonation, and seismic prospecting. This is particularly true for low-cost dense spatial sampling projects. Arai and Tokimatsu (2004) proposed to use average energy densities to compose the ratios. It means that H/V comes from the square root of the ratio of averages. On the other hand, a popular approach makes the average of spectral ratios. For ergodic processes peak values are usually the same using these two approaches. Sometimes however, the observations are insufficient and computed values for low frequencies display large variability and the corresponding H/V estimates may be inaccurate. The bias caused by localized sources may be the source of errors in the estimates. In this work we propose to compute the NHVSR using the Autocorrelations of Coda of Autocorrelations. This ACA approach is inspired in the work by Stehly et al. (2008). They used the Correlations of Coda of Correlations (C3) to isotropize the field. In our ACA approach the whole time series, say of 30 minutes, for each component is autocorrelated and the averages of the spectral density of selected windows (late coda windows are eliminated) are then improved estimates of directional energy densities. The computation of NHVSR using ACA appears more stable and free of transient effects. It remains to establish how this may be accounted for in forward calculation of H/V spectral ratios for models like a layered medium (e.g. Sánchez-Sesma et al., 2011; Albarello and Lunedei, 2011). This will require further scrutiny. References. Albarello, D. & E. Lunedei (2011). Structure of ambient vibration wavefield in the frequency range of engineering interest ([0.5, 20] Hz): insights from numerical modelling. Near Surface Geophysics 9, 543-559. Arai, H. & K. Tokimatsu (2004). S-wave velocity profiling by inversion of microtremor H/V spectrum, Bull. Seismol. Soc. Am. 94, 53-63. Sánchez-Sesma, F. J., M. Rodr
spectral analysis of ground magnetic data in magadi area, southern ...
Mgina
issue from fractures distributed along the shores of the lake. Presence of ... Spectral analysis involving determining power spectrum was applied to magnetic data along selected profiles ... of Lake Magadi issuing from the base of fault scarps.
Spectral Analysis of Broadband Seismic Array Data, Tien Shan
Shamshy, S.; Pavlis, G. L.
2003-12-01
We used a spectral analysis method to examine amplitude variations of body waves recorded in the Tien Shan region of central Asia. We used broadband data from the Kyrgyz Network (KNET), Kazakhstan Network (KZNET), and from a set of temporary, PASSCAL stations operated from 1997-2000 we refer to as the Ghengis array. A spectral ratio method similar to that used by Wilson and Pavlis (2000) was employed, but with station AAK used as a reference instead of the array median. Spectral ratios were estimated for all teleseismic events and a larger, intermediate depth events from the Hindu-Kush region for all three-components of ground motion and total signal strength on all components. Results are visualized by maps of amplitude for various frequency bands and through the 4-D animation method introduced by Wilson and Pavlis (2000). Data from Hindu-Kush events showed amplitude variations as much as a factor of 100 across the study area with a strong frequency dependence. The largest variations were at the highest frequencies observed near 15 Hz. Stations in the northwestern part of the Tien Shan array show little variation in amplitude relative to the reference station, AAK. In the central and eastern part of the array, the amplitude estimates are significantly smaller at all frequencies. In contrast, for stations in the western Tien Shan near the Talas-Fergana Fault, and the southern Tien Shan near the Tarim Basin, the amplitude values become much larger than the reference site. The teleseismic data show a different pattern and show a somewhat smaller, overall amplitude variation at comparable frequencies. The northern part of the array again shows small variations relative to the reference stations. There are some amplifications in the southern stations of the array, especially in the Tarim Basin. The higher frequency observations that show large amplifications at stations in the Tarim Basin are readily explained by site effects due to the thick deposits of sediments
Schael, S.; Bruneliere, R.; De Bonis, I.; Decamp, D.; Goy, C.; Jezequel, S.; Lees, J.-P.; Martin, F.; Merle, E.; Minard, M.-N.; Pietrzyk, B.; Trocme, B.; Bravo, S.; Casado, M.P.; Chmeissani, M.; Crespo, J.M.; Fernandez, E.; Fernandez-Bosman, M.; Garrido, Ll.; Martinez, M.; Pacheco, A.; Ruiz, H.; Colaleo, A.; Creanza, D.; De Filippis, N.; de Palma, M.; Iaselli, G.; Maggi, G.; Maggi, M.; Nuzzo, S.; Ranieri, A.; Raso, G.; Ruggieri, F.; Selvaggi, G.; Silvestris, L.; Tempesta, P.; Tricomi, A.; Zito, G.; Huang, X.; Lin, J.; Ouyang, Q.; Wang, T.; Xie, Y.; Xu, R.; Xue, S.; Zhang, J.; Zhang, L.; Zhao, W.; Abbaneo, D.; Barklow, T.; Buchmuller, O.; Cattaneo, M.; Clerbaux, B.; Drevermann, H.; Forty, R.W.; Frank, M.; Gianotti, F.; Hansen, J.B.; Harvey, J.; Hutchcroft, D.E.; Janot, P.; Jost, B.; Kado, M.; Mato, P.; Moutoussi, A.; Ranjard, F.; Rolandi, L.; Schlatter, D.; Teubert, F.; Valassi, A.; Videau, I.; Badaud, F.; Dessagne, S.; Falvard, A.; Fayolle, D.; Gay, P.; Jousset, J.; Michel, B.; Monteil, S.; Pallin, D.; Pascolo, J.M.; Perret, P.; Hansen, J.D.; Hansen, J.R.; Hansen, P.H.; Kraan, A.C.; Nilsson, B.S.; Kyriakis, A.; Markou, C.; Simopoulou, E.; Vayaki, A.; Zachariadou, K.; Blondel, A.; Brient, J.-C.; Machefert, F.; Rouge, A.; Videau, H.; Ciulli, V.; Focardi, E.; Parrini, G.; Antonelli, A.; Antonelli, M.; Bencivenni, G.; Bossi, F.; Capon, G.; Cerutti, F.; Chiarella, V.; Laurelli, P.; Mannocchi, G.; Murtas, G.P.; Passalacqua, L.; Kennedy, J.; Lynch, J.G.; Negus, P.; O'Shea, V.; Thompson, A.S.; Wasserbaech, S.; Cavanaugh, R.; Dhamotharan, S.; Geweniger, C.; Hanke, P.; Hepp, V.; Kluge, E.E.; Putzer, A.; Stenzel, H.; Tittel, K.; Wunsch, M.; Phys., Kirchhoff Inst.; Beuselinck, R.; Cameron, W.; Davies, G.; Dornan, P.J.; Girone, M.; Marinelli, N.; Nowell, J.; Rutherford, S.A.; Sedgbeer, J.K.; Thompson, J.C.; White, R.; Ghete, V.M.; Girtler, P.; Kneringer, E.; Kuhn, D.; Rudolph, G.; Bouhova-Thacker, E.; Bowdery, C.K.; Clarke, D.P.; Ellis, G.; Finch, A.J.; Foster, F.; Hughes, G.; Jones, R.W.L.; Pearson, M.R.; Robertson, N.A.; Smizanska, M.; van der Aa, O.; Delaere, C.; Leibenguth, G.; Lemaitre, V.; Blumenschein, U.; Holldorfer, F.; Jakobs, K.; Kayser, F.; Muller, A.-S.; Renk, B.; Sander, H.-G.; Schmeling, S.; Wachsmuth, H.; Zeitnitz, C.; Ziegler, T.; Bonissent, A.; Coyle, P.; Curtil, C.; Ealet, A.; Fouchez, D.; Payre, P.; Tilquin, A.; Ragusa, F.; David, A.; Dietl, H.; Ganis, G.; Huttmann, K.; Lutjens, G.; Manner, W.; Moser, H.-G.; Settles, R.; Villegas, M.; Wolf, G.; Boucrot, J.; Callot, O.; Davier, M.; Duflot, L.; Grivaz, J.-F.; Heusse, Ph.; Hocker, Andreas; Jacholkowska, A.; Serin, L.; Veillet, J.-J.; Yuan, C.Z.; Zhang, Z.Q.; Azzurri, P.; Bagliesi, Giuseppe; Boccali, T.; Foa, L.; Giammanco, A.; Giassi, A.; Ligabue, F.; Messineo, A.; Palla, F.; Sanguinetti, G.; Sciaba, A.; Sguazzoni, G.; Spagnolo, P.; Tenchini, R.; Venturi, A.; Verdini, P.G.; Awunor, O.; Blair, G.A.; Cowan, G.; Garcia-Bellido, A.; Green, M.G.; Medcalf, T.; Misiejuk, A.; Strong, J.A.; Teixeira-Dias, P.; Clifft, R.W.; Edgecock, T.R.; Norton, P.R.; Tomalin, I.R.; Ward, J.J.; Bloch-Devaux, Brigitte; Boumediene, D.; Colas, P.; Fabbro, B.; Lancon, E.; Lemaire, M.-C.; Locci, E.; Perez, P.; Rander, J.; Tuchming, B.; Vallage, G.; Litke, A.M.; Taylor, G.; Booth, C.N.; Cartwright, S.; Combley, F.; Hodgson, P.N.; Lehto, M.; Thompson, L.F.; Bohrer, A.; Brandt, S.; Grupen, C.; Hess, J.; Ngac, A.; Prange, G.; Borean, C.; Giannini, G.; He, H.; Putz, J.; Rothberg, J.; Armstrong, S.R.; Berkelman, Karl; Cranmer, K.; Ferguson, D.P.S.; Gao, Y.; Gonzalez, S.; Hayes, O.J.; Hu, H.; Jin, S.; Kile, J.; McNamara, P.A., III; Nielsen, J.; Pan, Y.B.; von Wimmersperg-Toeller, J.H.; Wiedenmann, W.; Wu, J.; Wu, Sau Lan; Wu, X.; Zobernig, G.; Dissertori, G.
2005-01-01
The full LEP-1 data set collected with the ALEPH detector at the $Z$ pole during 1991-1995 is analysed in order to measure the $\\tau$ decay branching fractions. The analysis follows the global method used in the published study based on 1991-1993 data, but several improvements are introduced, especially concerning the treatment of photons and $\\pi^0$'s. Extensive systematic studies are performed, in order to match the large statistics of the data sample corresponding to over 300\\,000 measured and identified $\\tau$ decays. Branching fractions are obtained for the two leptonic channels and eleven hadronic channels defined by their respective numbers of charged particles and $\\pi^0$'s. Using previously published ALEPH results on final states with charged and neutral kaons, corrections are applied to the hadronic channels to derive branching ratios for exclusive final states without kaons. Thus the analyses of the full LEP-1 ALEPH data are combined to yield a complete description of $\\tau$ decays, encompassing 22...
A Bayesian Analysis of Spectral ARMA Model
Manoel I. Silvestre Bezerra
2012-01-01
Full Text Available Bezerra et al. (2008 proposed a new method, based on Yule-Walker equations, to estimate the ARMA spectral model. In this paper, a Bayesian approach is developed for this model by using the noninformative prior proposed by Jeffreys (1967. The Bayesian computations, simulation via Markov Monte Carlo (MCMC is carried out and characteristics of marginal posterior distributions such as Bayes estimator and confidence interval for the parameters of the ARMA model are derived. Both methods are also compared with the traditional least squares and maximum likelihood approaches and a numerical illustration with two examples of the ARMA model is presented to evaluate the performance of the procedures.
Spectral Analysis of Diffusions with Jump Boundary
Kolb, Martin
2011-01-01
In this paper we consider one-dimensional diffusions with constant coefficients in a finite interval with jump boundary and a certain deterministic jump distribution. We use coupling methods in order to identify the spectral gap in the case of a large drift and prove that that there is a threshold drift above which the bottom of the spectrum no longer depends on the drift. As a Corollary to our result we are able to answer two questions concerning elliptic eigenvalue problems with non-local boundary conditions formulated previously by Iddo Ben-Ari and Ross Pinsky.
Multitemporal spectral analysis for cheatgrass (Bromus tectorum) classification.
Singh, Nagendra [ORNL; Glenn, Nancy F [Idaho State University
2009-07-01
Operational satellite remote sensing data can provide the temporal repeatability necessary to capture phenological differences among species. This study develops a multitemporal stacking method coupled with spectral analysis for extracting information from Landsat imagery to provide species-level information. Temporal stacking can, in an approximate mathematical sense, effectively increase the 'spectral' resolution of the system by adding spectral bands of several multitemporal images. As a demonstration, multitemporal linear spectral unmixing is used to successfully delineate cheatgrass (Bromus tectorum) from soil and surrounding vegetation (77% overall accuracy). This invasive plant is an ideal target for exploring multitemporal methods because of its phenological differences with other vegetation in early spring and, to a lesser degree, in late summer. The techniques developed in this work are directly applicable for other targets with temporally unique spectral differences.
Quantitative Analysis of Spectral Impacts on Silicon Photodiode Radiometers: Preprint
Myers, D. R.
2011-04-01
Inexpensive broadband pyranometers with silicon photodiode detectors have a non-uniform spectral response over the spectral range of 300-1100 nm. The response region includes only about 70% to 75% of the total energy in the terrestrial solar spectral distribution from 300 nm to 4000 nm. The solar spectrum constantly changes with solar position and atmospheric conditions. Relative spectral distributions of diffuse hemispherical irradiance sky radiation and total global hemispherical irradiance are drastically different. This analysis convolves a typical photodiode response with SMARTS 2.9.5 spectral model spectra for different sites and atmospheric conditions. Differences in solar component spectra lead to differences on the order of 2% in global hemispherical and 5% or more in diffuse hemispherical irradiances from silicon radiometers. The result is that errors of more than 7% can occur in the computation of direct normal irradiance from global hemispherical irradiance and diffuse hemispherical irradiance using these radiometers.
Hyper-spectral scanner design and analysis
Canavan, G.; Moses, J.; Smith, R.
1996-06-01
This is the final report of a two-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). An earlier project produced rough designs for key components of a compact hyper-spectral sensor for environmental and ecological measurements. Such sensors could be deployed on unmanned vehicles, aircraft, or satellites for measurements important to agriculture, the environment, and ecologies. This represents an important advance in remote sensing. Motorola invited us to propose an add-on, proof-of-principle sensor for their Comet satellite, whose primary mission is to demonstrate a channel of the IRIDIUM satellite communications system. Our project converted the preliminary designs from the previous effort into final designs for the telescope, camera, computer and interfaces that constitute the hyper-spectral scanning sensor. The work concentrated on design, fabrication, preliminary integration, and testing of the electronic circuit boards for the computer, data compression board, and interface board for the camera-computer and computer-modulator (transmitter) interfaces.
X-ray dual energy spectral parameter optimization for bone Calcium/Phosphorus mass ratio estimation
Sotiropoulou, P. I.; Fountos, G. P.; Martini, N. D.; Koukou, V. N.; Michail, C. M.; Valais, I. G.; Kandarakis, I. S.; Nikiforidis, G. C.
2015-09-01
Calcium (Ca) and Phosphorus (P) bone mass ratio has been identified as an important, yet underutilized, risk factor in osteoporosis diagnosis. The purpose of this simulation study is to investigate the use of effective or mean mass attenuation coefficient in Ca/P mass ratio estimation with the use of a dual-energy method. The investigation was based on the minimization of the accuracy of Ca/P ratio, with respect to the Coefficient of Variation of the ratio. Different set-ups were examined, based on the K-edge filtering technique and single X-ray exposure. The modified X-ray output was attenuated by various Ca/P mass ratios resulting in nine calibration points, while keeping constant the total bone thickness. The simulated data were obtained considering a photon counting energy discriminating detector. The standard deviation of the residuals was used to compare and evaluate the accuracy between the different dual energy set-ups. The optimum mass attenuation coefficient for the Ca/P mass ratio estimation was the effective coefficient in all the examined set-ups. The variation of the residuals between the different set-ups was not significant.
Laor, Ari; Bahcall, John N.; Jannuzi, Buell T.; Schneider, Donald P.; Green, Richard F.; Hartig, George F.
1994-01-01
We analyze the ultraviolet (UV) emission line and continuum properties of five low-redshift active galactic nuclei (four luminous quasars: PKS 0405-123, H1821 + 643, PG 0953 + 414, and 3C 273, and one bright Seyfert 1 galaxy: Mrk 205). The HST spectra have higher signal-to-noise ratios (typically approximately 60 per resolution element) and spectral resolution (R = 1300) than all previously published UV spectra used to study the emission characteristics of active galactic nuclei. We include in the analysis ground-based optical spectra covering H beta and the narrow (O III) lambda lambda 4959, 5007 doublet. New results are obtained and presented.
Comprehensive spectral analysis of Cyg X-1 using RXTE data
Rizwan Shahid; Ranjeev Misra; S.N.A.Jaaffrey
2012-01-01
We analyze a large number (＞ 500) of pointed Rossi X-Ray Timing Explorer (RXTE) observations of Cyg X- 1 and model the spectrum of each one.A subset of the observations for which there is a simultaneous reliable measure of the hardness ratio by the All Sky Monitor shows that the sample covers nearly all the spectral shapes of Cyg X-1.Each observation is fitted with a generic empirical model consisting of a disk black body spectrum,a Comptonized component whose input photon shape is the same as the disk emission,a Gaussian to represent the iron line and a reflection feature.The relative strength,width of the iron line and the reflection parameter are in general correlated with the high energy photon spectral index Γ.This is broadly consistent with a geometry where for the hard state (low Γ ～ 1.7) there is a hot inner Comptonizing region surrounded by a truncated cold disk.The inner edge of the disk moves inwards as the source becomes softer till finally in the soft state (high Γ ＞ 2.2) the disk fills the inner region and active regions above the disk produce the Comptonized component.However,the reflection parameter shows non-monotonic behavior near the transition region (Γ ～ 2),which suggests a more complex geometry or physical state of the reflector.In addition,the inner disk temperature,during the hard state,is on average higher than in the soft one,albeit with large scatter.These inconsistencies could be due to limitations in the data and the empirical model used to fit them.The flux of each spectral component is well correlated with Γ,which shows that unlike some other black hole systems,Cyg X- 1 does not show any hysteresis behavior.In the soft state,the flux of the Comptonized component is always similar to the disk one,which confirms that the ultra-soft state (seen in other brighter black hole systems) is not exhibited by Cyg X- 1.The rapid variation of the Compton amplification factor with Γ naturally explains the absence of spectra with Γ
Spectral luminosity indicators in SNe Ia - Understanding the R(SiII) line strength ratio and beyond
Hachinger, Stephan; Tanaka, Masaomi; Hillebrandt, Wolfgang; Benetti, Stefano
2008-01-01
SNe Ia are good distance indicators because the shape of their light curves, which can be measured independently of distance, varies smoothly with luminosity. This suggests that SNe Ia are a single family of events. Similar correlations are observed between luminosity and spectral properties. In particular, the ratio of the strengths of the SiII \\lambda 5972 and \\lambda 6355 lines, known as R(SiII), was suggested as a potential luminosity indicator. Here, the physical reasons for the observed correlation are investigated. A Monte-Carlo code is used to construct a sequence of synthetic spectra resembling those of SNe with different luminosities near B maximum. The influence of abundances and of ionisation and excitation conditions on the synthetic spectral features is investigated. The ratio R(SiII) depends ssentially on the strength of SiII \\lambda 5972, because SiII \\lambda 6355 is saturated. In less luminous objects, SiII \\lambda 5972 is stronger because of a rapidly increasing SiII/SiIII ratio. Thus, the c...
Liu Kun-Sung
2017-01-01
Full Text Available The soil-structure interaction (SSI can significantly alter the characteristics of recorded motions in buildings. The ratio of Fourier amplitude spectrum of the top-story accelerations to that of the foundation accelerations permits the identification of the natural frequency of the fixed-base building. In this study, records of the Chi-Chi earthquake and the 1226 Hengchun earthquake doublet from the structural array in a 51-story highrise building are used to obtain the dynamic characteristics of the buildings by the transfer function (TF method. As a result, the acceleration amplification of seismic excitation on the 47th storey of buildings is 4.24, in the horizontal component, from the Chi-Chi earthquake data greater than those of the 1226 Hengchun earthquake doublet with a value of 2.82 and 2.06, respectively. In addition, from the spectral ratio of the accelerations (47th floor/basement, together with the Fourier Amplitude Spectrum (FAS of the 47th floor and basement accelerations, it is noted that the peaks of the 47th floor FAS and the spectral ratio appear to coincide with each other from the records of 1226 Hengchun earthquake doublet, suggesting that there is no significant SSI effects in both the longitudinal and transverse directions.
Mitochondrial DNA depletion analysis by pseudogene ratioing.
Swerdlow, Russell H; Redpath, Gerard T; Binder, Daniel R; Davis, John N; VandenBerg, Scott R
2006-01-30
The mitochondrial DNA (mtDNA) depletion status of rho(0) cell lines is typically assessed by hybridization or polymerase chain reaction (PCR) experiments, in which the failure to hybridize mtDNA or amplify mtDNA using mtDNA-directed primers suggests thorough mitochondrial genome removal. Here, we report the use of an mtDNA pseudogene ratioing technique for the additional confirmation of rho0 status. Total genomic DNA from a U251 human glioma cell line treated with ethidium bromide was amplified using primers designed to anneal either mtDNA or a previously described nuclear DNA-embedded mtDNA pseudogene (mtDNApsi). The resultant PCR product was used to generate plasmid clones. Sixty-two plasmid clones were genotyped, and all arose from mtDNApsi template. These data allowed us to determine with 95% confidence that the resultant mtDNA-depleted cell line contains less than one copy of mtDNA per 10 cells. Unlike previous hybridization or PCR-based analyses of mtDNA depletion, this mtDNApsi ratioing technique does not rely on interpretation of a negative result, and may prove useful as an adjunct for the determination of rho0 status or mtDNA copy number.
Broadband Spectral Analysis of Aql X-1
Raichur, H; Dewangan, G
2011-01-01
We present the results of a broadband spectral study of the transient Low Mass X-ray Binary Aql X-1 observed by Suzaku and Rossi X-ray Timing Explorer satellites. The source was observed during its 2007 outburst in the High/Soft (Banana) state and in the Low/Hard (Extreme Island) state. Both the Banana state and the Extreme Island state spectra are best described by a two component model consisting of a soft multi-colour blackbody emission likely originating from the accretion disk and a harder Comptonized emission from the boundary layer. Evidence for a hard tail (extending to ~50 keV) is found during the Banana state; this further (transient) component, accounting for atleast ~1.5% of the source luminosity, is modeled by a power-law. Aql X-1 is the second Atoll source after GX 13+1 to show a high energy tail. The presence of a weak but broad Fe line provides further support for a standard accretion disk extending nearly to the neutron star surface. The input photons for the Comptonizing boundary layer could...
Spectral Analysis and Atmospheric Models of Microflares
Cheng Fang; Yu-Hua Tang; Zhi Xu
2006-01-01
By use of the high-resolution spectral data obtained with THEMIS on 2002 September 5, the spectra and characteristics of five well-observed microflares have been analyzed. Our results indicate that some of them are located near the longitudinal magnetic polarity inversion lines. All the microflares are accompanied by mass motions. The most obvious characteristic of the Hα microflare spectra is the emission at the center of both Hα and CaII 8542(A) lines. For the first time both thermal and non-thermal semi-empirical atmospheric models for the conspicuous and faint microflares are computed. In computing the non-thermal models, we assume that the electron beam resulting from magnetic reconnection is produced in the chromosphere, because it requires lower energies for the injected particles.It is found there is obvious heating in the low chromosphere. The temperature enhancement is about 1000-2200 K in the thermal models. If the non-thermal effects are included, then the required temperature increase can be reduced by 100-150 K. These imply that the Hα microflares can probably be produced by magnetic reconnection in the solar Iower atmosphere.The radiative and kinetic energies of the Hα microflares are estimated and the total energy is found to be 1027 - 4× 1028 erg.
Simulated spectra for QA/QC of spectral analysis software
Jackman, K. R. (Kevin R.); Biegalski, S. R.
2004-01-01
Monte Carlo simulated spectra have been developed to test the peak analysis algorithms of several spectral analysis software packages. Using MCNP 5, generic sample spectra were generated in order to perform ANSI N42.14 standard spectral tests on Canberra Genie-2000, Ortec GammaVision, and UniSampo. The reference spectra were generated in MCNP 5 using an F8, pulse height, tally with a detector model of an actual Germanium detector used in counting. The detector model matches the detector resolution, energy calibration, and efficiency. The simulated spectra have been found to be useful in testing the reliability and performance of spectral analysis programs. The detector model used was found to be useful in testing the performance of modern spectral analysis software tools. The software packages were analyzed and found to be in compliance with the ANSI 42.14 tests of the peak-search and peak-fitting algorithms. This method of using simulated spectra can be used to perform the ANSI 42.14 tests on the reliability and performance of spectral analysis programs in the absence of standard radioactive materials.
Induction Motor Speed Estimation by Using Spectral Current Analysis
2009-01-01
An interesting application for the FFT analysis is related to the induction motor speed estimation based on spectral current analysis. The paper presents the possibility of induction motor speed estimation by using the current harmonics generated because of the rotor slots and of the eccentricity.
Multi-spectral Image Analysis for Astaxanthin Coating Classification
Ljungqvist, Martin Georg; Ersbøll, Bjarne Kjær; Nielsen, Michael Engelbrecht
2011-01-01
Industrial quality inspection using image analysis on astaxanthin coating in aquaculture feed pellets is of great importance for automatic production control. In this study multi-spectral image analysis of pellets was performed using LDA, QDA, SNV and PCA on pixel level and mean value of pixels...
Spectral mixture analysis of EELS spectrum-images
Dobigeon, Nicolas [University of Toulouse, IRIT/INP-ENSEEIHT, 2 rue Camichel, 31071 Toulouse Cedex 7 (France); Brun, Nathalie, E-mail: nathalie.brun@u-psud.fr [University of Paris Sud, Laboratoire de Physique des Solides, CNRS, UMR 8502, 91405 Orsay Cedex (France)
2012-09-15
Recent advances in detectors and computer science have enabled the acquisition and the processing of multidimensional datasets, in particular in the field of spectral imaging. Benefiting from these new developments, Earth scientists try to recover the reflectance spectra of macroscopic materials (e.g., water, grass, mineral types Horizontal-Ellipsis ) present in an observed scene and to estimate their respective proportions in each mixed pixel of the acquired image. This task is usually referred to as spectral mixture analysis or spectral unmixing (SU). SU aims at decomposing the measured pixel spectrum into a collection of constituent spectra, called endmembers, and a set of corresponding fractions (abundances) that indicate the proportion of each endmember present in the pixel. Similarly, when processing spectrum-images, microscopists usually try to map elemental, physical and chemical state information of a given material. This paper reports how a SU algorithm dedicated to remote sensing hyperspectral images can be successfully applied to analyze spectrum-image resulting from electron energy-loss spectroscopy (EELS). SU generally overcomes standard limitations inherent to other multivariate statistical analysis methods, such as principal component analysis (PCA) or independent component analysis (ICA), that have been previously used to analyze EELS maps. Indeed, ICA and PCA may perform poorly for linear spectral mixture analysis due to the strong dependence between the abundances of the different materials. One example is presented here to demonstrate the potential of this technique for EELS analysis. -- Highlights: Black-Right-Pointing-Pointer EELS spectrum images are identical to hyperspectral images for Earth science. Black-Right-Pointing-Pointer Spectral unmixing algorithms have proliferated in the remote sensing field. Black-Right-Pointing-Pointer These powerful techniques can be successfully applied to EELS mapping. Black-Right-Pointing-Pointer Potential
Analysis of spectral methods for the homogeneous Boltzmann equation
Filbet, Francis
2011-04-01
The development of accurate and fast algorithms for the Boltzmann collision integral and their analysis represent a challenging problem in scientific computing and numerical analysis. Recently, several works were devoted to the derivation of spectrally accurate schemes for the Boltzmann equation, but very few of them were concerned with the stability analysis of the method. In particular there was no result of stability except when the method was modified in order to enforce the positivity preservation, which destroys the spectral accuracy. In this paper we propose a new method to study the stability of homogeneous Boltzmann equations perturbed by smoothed balanced operators which do not preserve positivity of the distribution. This method takes advantage of the "spreading" property of the collision, together with estimates on regularity and entropy production. As an application we prove stability and convergence of spectral methods for the Boltzmann equation, when the discretization parameter is large enough (with explicit bound). © 2010 American Mathematical Society.
Enveloping Spectral Surfaces: Covariate Dependent Spectral Analysis of Categorical Time Series.
Krafty, Robert T; Xiong, Shuangyan; Stoffer, David S; Buysse, Daniel J; Hall, Martica
2012-09-01
Motivated by problems in Sleep Medicine and Circadian Biology, we present a method for the analysis of cross-sectional categorical time series collected from multiple subjects where the effect of static continuous-valued covariates is of interest. Toward this goal, we extend the spectral envelope methodology for the frequency domain analysis of a single categorical process to cross-sectional categorical processes that are possibly covariate dependent. The analysis introduces an enveloping spectral surface for describing the association between the frequency domain properties of qualitative time series and covariates. The resulting surface offers an intuitively interpretable measure of association between covariates and a qualitative time series by finding the maximum possible conditional power at a given frequency from scalings of the qualitative time series conditional on the covariates. The optimal scalings that maximize the power provide scientific insight by identifying the aspects of the qualitative series which have the most pronounced periodic features at a given frequency conditional on the value of the covariates. To facilitate the assessment of the dependence of the enveloping spectral surface on the covariates, we include a theory for analyzing the partial derivatives of the surface. Our approach is entirely nonparametric, and we present estimation and asymptotics in the setting of local polynomial smoothing.
Guli·Japper; CHEN Xi; ZHAO Jin; MA ZhongGuo; CHANG Cun; ZHANG XueRen
2007-01-01
A structural mode was used to characterize vegetation composition at the plant leaf level and a flourishing-withering ratio was developed. The spectral responses of vegetation with different flourishing-withering ratios were analyzed, the change rates of the chlorophyll and moisture content indices of vegetation with different flourishing-withering ratios were compared, and correlations between the chlorophyll and moisture content indices were analyzed. The results reveal that leaves with an intermediate flourishing-withering ratio can increase the absorption signatures of vegetation and that band ranges of 570-700 nm and 1300-1540 nm can play a role in indicating changes in the flourishing-withering ratios of vegetation; NPQI, NPCI, R695/R420, R695/R760, R750/R700, the peak-value area of red selvedge, the red selvedge amplitude, the ratio between the red selvedge amplitude and the minimum amplitude, and the NDVl of vegetation change regularly with the change in flourishing-withering ratios,and these nine vegetation indices are highly related to the chlorophyll content. Vegetation indexes of NDWI and PRI are very sensitive to the flourishing-withering change in vegetation and are closely related to the moisture content, and the correlation coefficient is higher than 0.9. The derivative of the spectra is more effective in describing changes in the structural mode of vegetation with different flourishing-withering ratios, especially at band ranges of 552-628 nm and 630-686 nm, and it is more sensitive to the mixed flourishing-withering ratios of leaves rather than to the vegetation indices. The red selvedge position in the spectrum is highly related to the chlorophyll content and is not sensitive to changes in the structural mode of mixed flourishing-withering leaves. The red selvedge parameters are sensitive to changes in the flourishing-withering ratio at the peak-value area of the red selvedge amplitude and the ratio between the red selvedge amplitude and the
Mass Defect from Nuclear Physics to Mass Spectral Analysis
Pourshahian, Soheil
2017-09-01
Mass defect is associated with the binding energy of the nucleus. It is a fundamental property of the nucleus and the principle behind nuclear energy. Mass defect has also entered into the mass spectrometry terminology with the availability of high resolution mass spectrometry and has found application in mass spectral analysis. In this application, isobaric masses are differentiated and identified by their mass defect. What is the relationship between nuclear mass defect and mass defect used in mass spectral analysis, and are they the same? [Figure not available: see fulltext.
Spectral theory and nonlinear analysis with applications to spatial ecology
Cano-Casanova, S; Mora-Corral , C
2005-01-01
This volume details some of the latest advances in spectral theory and nonlinear analysis through various cutting-edge theories on algebraic multiplicities, global bifurcation theory, non-linear Schrödinger equations, non-linear boundary value problems, large solutions, metasolutions, dynamical systems, and applications to spatial ecology. The main scope of the book is bringing together a series of topics that have evolved separately during the last decades around the common denominator of spectral theory and nonlinear analysis - from the most abstract developments up to the most concrete applications to population dynamics and socio-biology - in an effort to fill the existing gaps between these fields.
Online Fault Diagnosis Method Based on Nonlinear Spectral Analysis
WEI Rui-xuan; WU Li-xun; WANG Yong-chang; HAN Chong-zhao
2005-01-01
The fault diagnosis based on nonlinear spectral analysis is a new technique for the nonlinear fault diagnosis, but its online application could be limited because of the enormous compution requirements for the estimation of general frequency response functions. Based on the fully decoupled Volterra identification algorithm, a new online fault diagnosis method based on nonlinear spectral analysis is presented, which can availably reduce the online compution requirements of general frequency response functions. The composition and working principle of the method are described, the test experiments have been done for damping spring of a vehicle suspension system by utilizing the new method, and the results indicate that the method is efficient.
Spectral Analysis of Large Particle Systems
Dahlbæk, Jonas
2017-01-01
The Fröhlich polaron model is defined as a quadratic form, and its discrete spectrum is studied for each fixed total momentum ξ ∈ R d in the weak coupling regime. Criteria are determined by means of which the number of discrete eigenvalues may be deduced. The analysis is based on relating...
Spectral analysis of the Chandra comet survey
Bodewits, D.; Christian, D. J.; Torney, M.; Dryer, M.; Lisse, C. M.; Dennerl, K.; Zurbuchen, T. H.; Wolk, S. J.; Tielens, A. G. G. M.; Hoekstra, R.
2007-01-01
Aims. We present results of the analysis of cometary X-ray spectra with an extended version of our charge exchange emission model (Bodewits et al. 2006). We have applied this model to the sample of 8 comets thus far observed with the Chandra X-ray observatory and acis spectrometer in the 300 - 1000
Spectral mixture analysis of EELS spectrum-images.
Dobigeon, Nicolas; Brun, Nathalie
2012-09-01
Recent advances in detectors and computer science have enabled the acquisition and the processing of multidimensional datasets, in particular in the field of spectral imaging. Benefiting from these new developments, Earth scientists try to recover the reflectance spectra of macroscopic materials (e.g., water, grass, mineral types…) present in an observed scene and to estimate their respective proportions in each mixed pixel of the acquired image. This task is usually referred to as spectral mixture analysis or spectral unmixing (SU). SU aims at decomposing the measured pixel spectrum into a collection of constituent spectra, called endmembers, and a set of corresponding fractions (abundances) that indicate the proportion of each endmember present in the pixel. Similarly, when processing spectrum-images, microscopists usually try to map elemental, physical and chemical state information of a given material. This paper reports how a SU algorithm dedicated to remote sensing hyperspectral images can be successfully applied to analyze spectrum-image resulting from electron energy-loss spectroscopy (EELS). SU generally overcomes standard limitations inherent to other multivariate statistical analysis methods, such as principal component analysis (PCA) or independent component analysis (ICA), that have been previously used to analyze EELS maps. Indeed, ICA and PCA may perform poorly for linear spectral mixture analysis due to the strong dependence between the abundances of the different materials. One example is presented here to demonstrate the potential of this technique for EELS analysis. Copyright © 2012 Elsevier B.V. All rights reserved.
HYPERSPECTRAL HYPERION IMAGERY ANALYSIS AND ITS APPLICATION USING SPECTRAL ANALYSIS
W. Pervez
2015-03-01
Full Text Available Rapid advancement in remote sensing open new avenues to explore the hyperspectral Hyperion imagery pre-processing techniques, analysis and application for land use mapping. The hyperspectral data consists of 242 bands out of which 196 calibrated/useful bands are available for hyperspectral applications. Atmospheric correction applied to the hyperspectral calibrated bands make the data more useful for its further processing/ application. Principal component (PC analysis applied to the hyperspectral calibrated bands reduced the dimensionality of the data and it is found that 99% of the data is held in first 10 PCs. Feature extraction is one of the important application by using vegetation delineation and normalized difference vegetation index. The machine learning classifiers uses the technique to identify the pixels having significant difference in the spectral signature which is very useful for classification of an image. Supervised machine learning classifier technique has been used for classification of hyperspectral image which resulted in overall efficiency of 86.6703 and Kappa co-efficient of 0.7998.
Spectral Synthesis via Mean Field approach to Independent Component Analysis
Hu, Ning; Su, Shan-Shan; Kong, Xu
2016-03-01
We apply a new statistical analysis technique, the Mean Field approach to Independent Component Analysis (MF-ICA) in a Bayseian framework, to galaxy spectral analysis. This algorithm can compress a stellar spectral library into a few Independent Components (ICs), and the galaxy spectrum can be reconstructed by these ICs. Compared to other algorithms which decompose a galaxy spectrum into a combination of several simple stellar populations, the MF-ICA approach offers a large improvement in efficiency. To check the reliability of this spectral analysis method, three different methods are used: (1) parameter recovery for simulated galaxies, (2) comparison with parameters estimated by other methods, and (3) consistency test of parameters derived with galaxies from the Sloan Digital Sky Survey. We find that our MF-ICA method can not only fit the observed galaxy spectra efficiently, but can also accurately recover the physical parameters of galaxies. We also apply our spectral analysis method to the DEEP2 spectroscopic data, and find it can provide excellent fitting results for low signal-to-noise spectra.
Comparison between Financial Ratios Analysis and Balanced Scorecard
Khalad M.S. Alrafadi
2011-01-01
Full Text Available Financial ratios have long been used as a tool to evaluate the overall financial performance of a company. However, in early 1990s, a new method called Balanced Scorecard has been introduced by Robert Kaplan and David Norton to evaluate the overall controlling of a company. Problem statement: To the best of my knowledge at present there are no letrature review comparing between Financial ratios and Balanced Scorecard. Approach: This study is a conceptual paper comparing between the financial ratios analysis and balanced scorecard method. The objective of this paper is to compare between the benefits and problems of using financial ratios analysis and Balanced Scorecard method in evaluating the overall control of the company. Results: As a result, we found that the Balanced Scorecard is more efficient than financial ratios analysis. Conclusion/Recommendations: Both the balanced scorecard and financial ratios analysis are important tools for evaluating performance. So, we cannot ignore either of them.
Nonlinear Laplacian spectral analysis of Rayleigh-Bénard convection
Brenowitz, N. D.; Giannakis, D.; Majda, A. J.
2016-06-01
The analysis of physical datasets using modern methods developed in machine learning presents unique challenges and opportunities. These datasets typically feature many degrees of freedom, which tends to increase the computational cost of statistical methods and complicate interpretation. In addition, physical systems frequently exhibit a high degree of symmetry that should be exploited by any data analysis technique. The classic problem of Rayleigh Benárd convection in a periodic domain is an example of such a physical system with trivial symmetries. This article presents a technique for analyzing the time variability of numerical simulations of two-dimensional Rayleigh-Bénard convection at large aspect ratio and intermediate Rayleigh number. The simulated dynamics are highly unsteady and consist of several convective rolls that are distributed across the domain and oscillate with a preferred frequency. Intermittent extreme events in the net heat transfer, as quantified by the time-weighted probability distribution function of the Nusselt number, are a hallmark of these simulations. Nonlinear Laplacian Spectral Analysis (NLSA) is a data-driven method which is ideally suited for the study of such highly nonlinear and intermittent dynamics, but the trivial symmetries of the Rayleigh-Bénard problem such as horizontal shift-invariance can mask the interesting dynamics. To overcome this issue, the vertical velocity is averaged over parcels of similar temperature and height, which substantially compresses the size of the dataset and removes trivial horizontal symmetries. This isothermally averaged dataset, which is shown to preserve the net convective heat-flux across horizontal surfaces, is then used as an input to NLSA. The analysis generates a small number of orthogonal modes which describe the spatiotemporal variability of the heat transfer. A regression analysis shows that the extreme events of the net heat transfer are primarily associated with a family of
A Review of Unsupervised Spectral Target Analysis for Hyperspectral Imagery
Yingzi Du
2010-01-01
Full Text Available One of great challenges in unsupervised hyperspectral target analysis is how to obtain desired knowledge in an unsupervised means directly from the data for image analysis. This paper provides a review of unsupervised target analysis by first addressing two fundamental issues, “what are material substances of interest, referred to as targets?” and “how can these targets be extracted from the data?” and then further developing least squares (LS-based unsupervised algorithms for finding spectral targets for analysis. In order to validate and substantiate the proposed unsupervised hyperspectral target analysis, three applications in endmember extraction, target detection and linear spectral unmixing are considered where custom-designed synthetic images and real image scenes are used to conduct experiments.
A Review of Unsupervised Spectral Target Analysis for Hyperspectral Imagery
Chang Mann-Li
2010-01-01
Full Text Available Abstract One of great challenges in unsupervised hyperspectral target analysis is how to obtain desired knowledge in an unsupervised means directly from the data for image analysis. This paper provides a review of unsupervised target analysis by first addressing two fundamental issues, "what are material substances of interest, referred to as targets?" and "how can these targets be extracted from the data?" and then further developing least squares (LS-based unsupervised algorithms for finding spectral targets for analysis. In order to validate and substantiate the proposed unsupervised hyperspectral target analysis, three applications in endmember extraction, target detection and linear spectral unmixing are considered where custom-designed synthetic images and real image scenes are used to conduct experiments.
X-ray spectral optimization for mammography applications using signal-to-noise ratio
Tucker, Jonathan Ernest
2000-07-01
A hypotheses that optimum exposure technique factors for mammography can be computed using uncorrected x-ray spectra measured with an inexpensive semiconductor detector is proven. A parametric model is developed, based upon the minimum signal-to-noise ratio required to perceive an object against background, to predict optimum exposure technique factors. Using published molybdenum- and rhodium-target x-ray spectra, the model predicts that aluminum-filtered molybdenum and rhodium spectra are optimum. The model is subsequently used to predict optimum exposure technique factors using uncorrected x- ray spectra from a GE Senographe DMR mammography unit measured with a cadmium zinc telluride detector and multichannel analyzer. The computed optimum exposure technique factors using uncorrected measured spectra and published spectra are comparable. The model is validated using the uncorrected measured spectra and a phantom containing objects mimicking microcalcifications and fibrous tissue structures. Entrance skin exposure and breast dose for aluminum-filtered spectra are well below those produced using currently popular k-edge filtered spectra. Aluminum-filtered spectra should be considered useful because (1)structures associated with breast cancer can be successfully imaged, and (2)the patient receives a greatly reduced dose.
Tomato sorting using independent component analysis on spectral images
Polder, G.; Heijden, van der G.W.A.M.; Young, I.T.
2003-01-01
Independent Component Analysis is one of the most widely used methods for blind source separation. In this paper we use this technique to estimate the most important compounds which play a role in the ripening of tomatoes. Spectral images of tomatoes were analyzed. Two main independent components
PIXE-quantified AXSIA : elemental mapping by multivariate spectral analysis.
Doyle, Barney Lee; Antolak, Arlyn J. (Sandia National Labs, Livermore, CA); Campbell, J. L. (University of Guelph, Guelph, ON, Canada); Ryan, C. G. (CSIRO Exploration and Mining Bayview Road, Clayton VIC, Australia); Provencio, Paula Polyak; Barrett, Keith E. (Primecore Systems, Albuquerque, NM,); Kotula, Paul Gabriel
2005-07-01
Automated, nonbiased, multivariate statistical analysis techniques are useful for converting very large amounts of data into a smaller, more manageable number of chemical components (spectra and images) that are needed to describe the measurement. We report the first use of the multivariate spectral analysis program AXSIA (Automated eXpert Spectral Image Analysis) developed at Sandia National Laboratories to quantitatively analyze micro-PIXE data maps. AXSIA implements a multivariate curve resolution technique that reduces the spectral image data sets into a limited number of physically realizable and easily interpretable components (including both spectra and images). We show that the principal component spectra can be further analyzed using conventional PIXE programs to convert the weighting images into quantitative concentration maps. A common elemental data set has been analyzed using three different PIXE analysis codes and the results compared to the cases when each of these codes is used to separately analyze the associated AXSIA principal component spectral data. We find that these comparisons are in good quantitative agreement with each other.
Spectangular - Spectral Disentangling For Detailed Chemical Analysis Of Binaries
Sablowski, Daniel
2016-08-01
Disentangling of spectra helps to improve the orbit parameters and allows detailed chemical analysis. Spectangular is a GUI program written in C++ for spectral disentangling of spectra of SB1 and SB2 systems. It is based on singular value decomposition in the wavelength space and is coupled to an orbital solution.The results are the component spectra and the orbital parameters.
Spectral Analysis using Linearly Chirped Gaussian Pulse Stacking
ZHENG Huan; WANG An-Ting; XU Li-Xin; MING Hai
2009-01-01
We analyze the spectrum of a stacked pulse with the technique of linearly chirped Gaussian pulse stacking.Our results show that there are modulation structures in the spectrum of the stacked pulse. The modulation frequencies are discussed in detail. By applying spectral analysis, we find that the intensity fluctuation cannot be smoothed by introducing an optical amplitude filter.
Spectral derivative analysis of solar spectroradiometric measurements: Theoretical basis
Hansell, R. A.; Tsay, S.-C.; Pantina, P.; Lewis, J. R.; Ji, Q.; Herman, J. R.
2014-07-01
Spectral derivative analysis, a commonly used tool in analytical spectroscopy, is described for studying cirrus clouds and aerosols using hyperspectral, remote sensing data. The methodology employs spectral measurements from the 2006 Biomass-burning Aerosols in Southeast Asia field study to demonstrate the approach. Spectral peaks associated with the first two derivatives of measured/modeled transmitted spectral fluxes are examined in terms of their shapes, magnitudes, and positions from 350 to 750 nm, where variability is largest. Differences in spectral features between media are mainly associated with particle size and imaginary term of the complex refractive index. Differences in derivative spectra permit cirrus to be conservatively detected at optical depths near the optical thin limit of ~0.03 and yield valuable insight into the composition and hygroscopic nature of aerosols. Biomass-burning smoke aerosols/cirrus generally exhibit positive/negative slopes, respectively, across the 500-700 nm spectral band. The effect of cirrus in combined media is to increase/decrease the slope as cloud optical thickness decreases/increases. For thick cirrus, the slope tends to 0. An algorithm is also presented which employs a two model fit of derivative spectra for determining relative contributions of aerosols/clouds to measured data, thus enabling the optical thickness of the media to be partitioned. For the cases examined, aerosols/clouds explain ~83%/17% of the spectral signatures, respectively, yielding a mean cirrus cloud optical thickness of 0.08 ± 0.03, which compared reasonably well with those retrieved from a collocated Micropulse Lidar Network Instrument (0.09 ± 0.04). This method permits extracting the maximum informational content from hyperspectral data for atmospheric remote sensing applications.
Spectral characteristics analysis of red tide water in mesocosm experiment
Cui, Tingwei; Zhang, Jie; Zhang, Hongliang; Ma, Yi; Gao, Xuemin
2003-05-01
Mesocosm ecosystem experiment with seawater enclosed of the red tide was carried out from July to September 2001. We got four species of biology whose quantities of bion are dominant in the red tide. During the whole process from the beginning to their dying out for every specie, in situ spectral measurements were carried out. After data processing, characteristic spectra of red tide of different dominant species are got. Via comparison and analysis of characteristics of different spectra, we find that in the band region between 685 and 735 nanometers, spectral characteristics of red tide is apparently different from that of normal water. Compared to spectra of normal water, spectra of red tide have a strong reflectance peak in the above band region. As to spectra of red tide dominated by different species, the situations of reflectance peaks are also different: the second peak of Mesodinium rubrum spectrum lies between 726~732 nm, which is more than 21nm away from the other dominant species spectra"s Leptocylindrus danicus"s second spectral peak covers 686~694nm; that of Skeletonema costatum lies between 691~693 nm. Chattonella marina"s second spectral peak lies about 703~705 nm. Thus we can try to determine whether red tide has occurred according to its spectral data. In order to monitor the event of red tide and identify the dominant species by the application of the technology of hyperspectral remote sensing, acquiring spectral data of different dominant species of red tide as much as possible becomes a basic work to be achieved for spectral matching, information extraction and so on based on hyperspectral data.
Image registration based on matrix perturbation analysis using spectral graph
Chengcai Leng; Zheng Tian; Jing Li; Mingtao Ding
2009-01-01
@@ We present a novel perspective on characterizing the spectral correspondence between nodes of the weighted graph with application to image registration.It is based on matrix perturbation analysis on the spectral graph.The contribution may be divided into three parts.Firstly, the perturbation matrix is obtained by perturbing the matrix of graph model.Secondly, an orthogonal matrix is obtained based on an optimal parameter, which can better capture correspondence features.Thirdly, the optimal matching matrix is proposed by adjusting signs of orthogonal matrix for image registration.Experiments on both synthetic images and real-world images demonstrate the effectiveness and accuracy of the proposed method.
Spectral analysis, digital integration, and measurement of low backscatter in coherent laser radar
Vaughan, J. M.; Callan, R. D.; Bowdle, D. A.; Rothermel, J.
1989-01-01
A method of surface acoustic wave (SAW) spectral analysis and digital integration that has been used previously in coherent CW laser work with CO2 lasers at 10.6 microns is described. Expressions are derived for the signal to noise ratio in the measured voltage spectrum with an approximation for the general case and rigorous treatment for the low signal case. The atmospheric backscatter data accumulated by the airborne LATAS (laser true airspeed) coherent laser radar system are analyzed.
Spectral Fatigue Analysis of Jacket Stuctures in Mumbai High Field
S. Nallayarasu
2010-09-01
Full Text Available Fatigue analysis of offshore structures is an integral part of design of offshore structures and shall be carried out with suitable method of discretising the seastate. Historically, for most of the fixed offshore structures, deterministic fatigue analysis found to predict the fatigue damage reasonably well and has been in use for several decades. Fixed structures with small topsides, mostly exhibit a static response characteristics and the natural period may be in the order of less than 2 seconds. Offshore platforms with larger production capacity and deeper water depths may require specialised treatment of seastate due to their dynamic characteristics more vulnerable for fatigue damage. A spectral fatigue analysis has been performed for two different platforms in Mumbai high field (MNP and RS14 and a comparison is made with deterministic analysis. The spectral fatigue analysis indicates that the predicted fatigue life is lower than the deterministic analysis since the dynamic amplification of wave loads are treated approximately in deterministic analysis. Hence for large structures, it recommended to use spectral methods to assess the fatigue life of tubular joints.
Long-slit spectral observations and stellar mass-to-light ratio of spiral galaxy UGC11919
Saburova, A; Uklein, R; Katkov, I
2015-01-01
We performed the long-slit observations of spiral galaxy UGC11919 with the Russian 6-m telescope to study its kinematics and stellar population. The previous studies gave basis to suspect that this galaxy possesses a peculiarly low mass-to-light ratio $M/L_B$ of stellar population which could indicate the presence of bottom-light stellar initial mass function (IMF). The ratio $M/L_B$ estimated for different evolutionary models of stellar population using both the broad-band magnitudes and the detailed spectral data confirms this peculiarity if the disc inclination angle $i>30^o$, as it was obtained earlier from the optical photometry, in a good agreement with the HI data cube modelling. However the re-processing of HI data cube we carried out showed that it is compatible with much lower value $i=13^o$ corresponding to the "normal" ratio $M/L_B$, which does not need any peculiar stellar IMF. Stellar velocity dispersion measured at one disc radial scalelength from the center also better agrees with the low disc...
Time frequency analysis of Jovian and Saturnian radio spectral patterns
Boudjada, Mohammed Y.; Galopeau, Patrick H. M.; Al-Haddad, Emad; Lammer, Helmut
2016-04-01
Prominent radio spectral patterns were observed by the Cassini Radio and Plasma Wave Science experiment (RPWS) principally at Jupiter and Saturn. The spectral shapes are displayed in the usual dynamic spectra showing the flux density versus the time and the frequency. Those patterns exhibit well-organized shapes in the time-frequency plane connected with the rotation of the planet. We consider in this analysis the auroral emissions which occurred in the frequency range between 10 kHz and approximately 3 MHz. It concerns the Jovian hectometric emission (HOM) and the Saturnian kilometric radiation (SKR). We show in the case of Jupiter's HOM that the spectral patterns are well-arranged arc structures with curvatures depending on the Jovian rotation. Regarding the SKR emission, the spectral shapes exhibit generally complex patterns, and only sometimes arc structures are observed. We emphasize the curve alterations from vertex-early to vertex-late arcs (and vice versa) and we study their dependences, or not, on the planetary rotations. We also discuss the common physical process at the origin of the HOM and SKR emissions, specifically the spectral patterns created by the interaction between planetary satellites (e.g. Io or Dione) and the Jovian and Saturnian magnetospheres.
Relationship between X-ray spectral index and X-ray Eddington ratio for Mrk 335 and Ark 564
Sarma, R; Misra, R; Dewangan, G; Pathak, A; Sarma, J K
2015-01-01
We present a comprehensive flux resolved spectral analysis of the bright Narrow line Seyfert I AGNs, Mrk~335 and Ark~564 using observations by XMM-Newton satellite. The mean and the flux resolved spectra are fitted by an empirical model consisting of two Comptonization components, one for the low energy soft excess and the other for the high energy power-law. A broad Iron line and a couple of low energies edges are required to explain the spectra. For Mrk~335, the 0.3 - 10 keV luminosity relative to the Eddington value, L{$_{X}$}/L$_{Edd}$, varied from 0.002 to 0.06. The index variation can be empirically described as $\\Gamma$ = 0.6 log$_{10}$ L{$_{X}$}/L$_{Edd}$ + 3.0 for $0.005 < L{_{X}}/L_{Edd} < 0.04$. At $ L_{{X}}/L_{Edd} \\sim 0.04$ the spectral index changes and then continues to follow $\\Gamma$ = 0.6 log$_{10}$ L$_{{X}}$/L$_{Edd}$ + 2.7, i.e. on a parallel track. We confirm that the result is independent of the specific spectral model used by fitting the data in the 3 - 10 keV band by only a powe...
An introduction to random vibrations, spectral & wavelet analysis
Newland, D E
2005-01-01
One of the first engineering books to cover wavelet analysis, this classic text describes and illustrates basic theory, with a detailed explanation of the workings of discrete wavelet transforms. Computer algorithms are explained and supported by examples and a set of problems, and an appendix lists ten computer programs for calculating and displaying wavelet transforms.Starting with an introduction to probability distributions and averages, the text examines joint probability distributions, ensemble averages, and correlation; Fourier analysis; spectral density and excitation response relation
Rivet, D.; Campillo, M.; Sanchez-Sesma, F.; Singh, S. K.
2012-04-01
We reconstruct Rayleigh and Love waves from cross-correlations of ambient seismic noise recorded at 19 broad-band stations of the MesoAmerica Seismic Experiment (MASE) and Valley of Mexico Experiment (VMEX). The cross-correlations are computed over 2 years of noise records for the 8 MASE stations and over 1 year for the 11 VMEX stations. We use surface waves with sufficient signal-to-noise ratio to measure group velocity dispersion curves at period of 0.5 to 3 seconds. For paths within the soft quaternary sediments basin, the maximum energy is observed at velocity higher than expected for the fundamental mode. This observation suggests the importance of higher modes as the main vectors of energy in such complex structures. To perform a reliable inversion of the velocity structure beneath the valley, an identification of these dominants modes is required. To identify the modes of surface waves we use the spectral ratio of the horizontal components over the vertical component (H/V) measured on seismic coda. We compare the observed values with the theoretical H/V for the velocity model deduced from surface wave dispersion when assuming a particular mode. H/V ratio in the coda is computed under the hypothesis of equipartition of a diffuse field in a layered medium following Margerin et al. [2009] and Sánchez-Sesma et al. [2011]. We processed several events to ensure that the observed H/V is stable. The comparison of the modelled dispersion and H/V ratio allows for mode identification, and consequently to recover the velocity model of the structure. We conclude on the predominance of higher modes in our observations. The excitation of higher modes is key element of explanation for the long duration and amplification of the seismic signals observed in the Valley of Mexico.
Kotula, Paul G; Keenan, Michael R
2006-12-01
Multivariate statistical analysis methods have been applied to scanning transmission electron microscopy (STEM) energy-dispersive X-ray spectral images. The particular application of the multivariate curve resolution (MCR) technique provides a high spectral contrast view of the raw spectral image. The power of this approach is demonstrated with a microelectronics failure analysis. Specifically, an unexpected component describing a chemical contaminant was found, as well as a component consistent with a foil thickness change associated with the focused ion beam specimen preparation process. The MCR solution is compared with a conventional analysis of the same spectral image data set.
Explorations in Statistics: The Analysis of Ratios and Normalized Data
Curran-Everett, Douglas
2013-01-01
Learning about statistics is a lot like learning about science: the learning is more meaningful if you can actively explore. This ninth installment of "Explorations in Statistics" explores the analysis of ratios and normalized--or standardized--data. As researchers, we compute a ratio--a numerator divided by a denominator--to compute a…
IMF and [Na/Fe] abundance ratios from optical and NIR Spectral Features in Early-type Galaxies
La Barbera, F; Ferreras, I; Pasquali, A; Prieto, C Allende; Rock, B; Aguado, D S; Peletier, R F
2016-01-01
We present a joint analysis of the four most prominent sodium-sensitive features (NaD, NaI8190, NaI1.14, and NaI2.21), in the optical and Near-Infrared spectral range, of two nearby, massive (sigma~300km/s), early-type galaxies (named XSG1 and XSG2). Our analysis relies on deep VLT/X-Shooter long-slit spectra, along with newly developed stellar population models, allowing for [Na/Fe] variations, up to 1.2dex, over a wide range of age, total metallicity, and IMF slope. The new models show that the response of the Na-dependent spectral indices to [Na/Fe] is stronger when the IMF is bottom heavier. For the first time, we are able to match all four Na features in the central regions of massive early-type galaxies, finding an overabundance of [Na/Fe], in the range 0.5-0.7dex, and a bottom-heavy IMF. Therefore, individual abundance variations cannot be fully responsible for the trends of gravity-sensitive indices, strengthening the case towards a non-universal IMF. Given current limitations of theoretical atmospher...
The meta-analysis of response ratios in experimental ecology
Hedges, L.V. [Univ. of Chicago, IL (United States). Dept. of Education; Gurevitch, J. [State Univ. of New York, Stony Brook, NY (United States). Dept. of Ecology and Evolution; Curtis, P.S. [Ohio State Univ., Columbus, OH (United States). Dept. of Plant Biology
1999-06-01
Meta-analysis provides formal statistical techniques for summarizing the results of independent experiments and is increasingly being used in ecology. The response ratio (the ratio of mean outcome in the experimental group to that in the control group) and closely related measures of proportionate change are often used as measures of effect magnitude in ecology. Using these metrics for meta-analysis requires knowledge of their statistical properties, but these have not been previously derived. The authors give the approximate sampling distribution of the log response ratio, discuss why it is a particularly useful metric for many applications in ecology, and demonstrate how to use it in meta-analysis. The meta-analysis of response-ratio data is illustrated using experimental data on the effects of increased atmospheric CO{sub 2} on plant biomass responses.
Outlier Detection with Space Transformation and Spectral Analysis
Dang, Xuan-Hong; Micenková, Barbora; Assent, Ira
2013-01-01
Detecting a small number of outliers from a set of data observations is always challenging. In this paper, we present an approach that exploits space transformation and uses spectral analysis in the newly transformed space for outlier detection. Unlike most existing techniques in the literature...... benefits the process of mapping data into a usually lower dimensional space. Outliers are then identified by spectral analysis of the eigenspace spanned by the set of leading eigenvectors derived from the mapping procedure. The proposed technique is purely data-driven and imposes no assumptions regarding...... the data distribution, making it particularly suitable for identification of outliers from irregular, non-convex shaped distributions and from data with diverse, varying densities....
Multi spectral imaging analysis for meat spoilage discrimination
Christiansen, Asger Nyman; Carstensen, Jens Michael; Papadopoulou, Olga
with corresponding sensory data would be of great interest. The purpose of this research was to produce a method capable of quantifying and/or predicting the spoilage status (e.g. express in TVC counts as well as on sensory evaluation) using a multi spectral image of a meat sample and thereby avoid any time...... classification methods: Naive Bayes Classifier as a reference model, Canonical Discriminant Analysis (CDA) and Support Vector Classification (SVC). As the final step, generalization of the models was performed using k-fold validation (k=10). Results showed that image analysis provided good discrimination of meat...... samples. In the case where all data were taken together the misclassification error amounted to 16%. When spoilage status was based on visual sensory data, the model produced a MER of 22% for the combined dataset. These results suggest that it is feasible to employ a multi spectral image...
Spectral analysis of sinus arrhythmia - A measure of mental effort
Vicente, Kim J.; Craig Thornton, D.; Moray, Neville
1987-01-01
The validity of the spectral analysis of sinus arrhythmia as a measure of mental effort was investigated using a computer simulation of a hovercraft piloted along a river as the experimental task. Strong correlation was observed between the subjective effort-ratings and the heart-rate variability (HRV) power spectrum between 0.06 and 0.14 Hz. Significant correlations were observed not only between subjects but, more importantly, within subjects as well, indicating that the spectral analysis of HRV is an accurate measure of the amount of effort being invested by a subject. Results also indicate that the intensity of effort invested by subjects cannot be inferred from the objective ratings of task difficulty or from performance.
Temporary spectral analysis of a laser plasma of mineral coal
Rebolledo, P.; Pacheco, P.; Sarmiento, R.; Cabanzo, R.; Mejía-Ospino, E.
2013-11-01
In this work we present results of the temporal spectral study of a plasma laser of mineral coal using the Laser-induced Breakdown Spectroscopy (LIBS) technique. The plasma was generated by focusing a laser beam of Nd:YAG laser emitting at 532 nm with energy per pulse of 35 mJ on coal target pellets. The plasma radiation was conducted by an optical fiber to the entrance slit of a spectrograph of 0.5 m, equipped with a 1200 and 2400 grooves/mm diffraction grating and an ICCD camera for registration with different delay times of the spectra in the spectral range from 250 nm to 900 nm. The temporal spectral analysis allowed the identification of the elements Al, Fe, Ca, Mg, K, and Si, and CN and C2 molecules present in natural coals. The characteristics of the spectral lines and bands were studied at different delay times obtaining the calculation of the evolution of electron temperature, electron density, and vibrational temperature of plasmas in the time. The delay times used were between 0.5 μs and 5 μs, calculating the electron temperature ranged between 5 000 K and 1 000 K.
Spectral Image Processing and Analysis of the Archimedes Palimpsest
2011-09-01
SPECTRAL IMAGE PROCESSING AND ANALYSIS OF THE ARCHIMEDES PALIMPSEST Roger L. Easton, Jr., William A. Christens-Barry, Keith T. Knox Chester F...5988 (fax), e-mail: easton@cis.rit.edu web: www.cis.rit.edu/people/faculty/easton ABSTRACT The Archimedes Palimpsest is a 10th-century parchment...rendering. 1. SIGNIFICANCE OF THE CODEX Almost everything known about the work of Archimedes has been gleaned from three codex manuscripts. The first
Ratio Versus Regression Analysis: Some Empirical Evidence in Brazil
Newton Carneiro Affonso da Costa Jr.
2004-06-01
Full Text Available This work compares the traditional methodology for ratio analysis, applied to a sample of Brazilian firms, with the alternative one of regression analysis both to cross-industry and intra-industry samples. It was tested the structural validity of the traditional methodology through a model that represents its analogous regression format. The data are from 156 Brazilian public companies in nine industrial sectors for the year 1997. The results provide weak empirical support for the traditional ratio methodology as it was verified that the validity of this methodology may differ between ratios.
Spectral principal component analysis of mid-infrared spectra of a sample of PG QSOs
Bian, Wei-Hao; Green, Richard; Shi, Yong; Ge, Xue; Liu, Wen-Shuai
2015-01-01
A spectral principal component analysis (SPCA) of a sample of 87 PG QSOs at $z < 0.5$ is presented for their mid-infrared spectra from Spitzer Space Telescope. We have derived the first five eigenspectra, which account for 85.2\\% of the mid-infrared spectral variation. It is found that the first eigenspectrum represents the mid-infrared slope, forbidden emission line strength and $9.7~\\mu m$ silicate feature, the 3rd and 4th eigenspectra represent the silicate features at $18~ \\mu m$ and $9.7~\\mu m$, respectively. With the principal components (PC) from optical PCA, we find that there is a medium strong correlation between spectral SPC1 and PC2 (accretion rate). It suggests that more nuclear contribution to the near-IR spectrum leads to the change of mid-IR slope. We find mid-IR forbidden lines are suppressed with higher accretion rate. A medium strong correlation between SPC3 and PC1 (Eddington ratio) suggests a connection between the silicate feature at $18~\\mu m$ and the Eddington ratio. For the ratio o...
Investigation of spectral analysis techniques for randomly sampled velocimetry data
Sree, Dave
1993-01-01
It is well known that velocimetry (LV) generates individual realization velocity data that are randomly or unevenly sampled in time. Spectral analysis of such data to obtain the turbulence spectra, and hence turbulence scales information, requires special techniques. The 'slotting' technique of Mayo et al, also described by Roberts and Ajmani, and the 'Direct Transform' method of Gaster and Roberts are well known in the LV community. The slotting technique is faster than the direct transform method in computation. There are practical limitations, however, as to how a high frequency and accurate estimate can be made for a given mean sampling rate. These high frequency estimates are important in obtaining the microscale information of turbulence structure. It was found from previous studies that reliable spectral estimates can be made up to about the mean sampling frequency (mean data rate) or less. If the data were evenly samples, the frequency range would be half the sampling frequency (i.e. up to Nyquist frequency); otherwise, aliasing problem would occur. The mean data rate and the sample size (total number of points) basically limit the frequency range. Also, there are large variabilities or errors associated with the high frequency estimates from randomly sampled signals. Roberts and Ajmani proposed certain pre-filtering techniques to reduce these variabilities, but at the cost of low frequency estimates. The prefiltering acts as a high-pass filter. Further, Shapiro and Silverman showed theoretically that, for Poisson sampled signals, it is possible to obtain alias-free spectral estimates far beyond the mean sampling frequency. But the question is, how far? During his tenure under 1993 NASA-ASEE Summer Faculty Fellowship Program, the author investigated from his studies on the spectral analysis techniques for randomly sampled signals that the spectral estimates can be enhanced or improved up to about 4-5 times the mean sampling frequency by using a suitable
Harmonic component detection: Optimized Spectral Kurtosis for operational modal analysis
Dion, J.-L.; Tawfiq, I.; Chevallier, G.
2012-01-01
This work is a contribution in the field of Operational Modal Analysis to identify the modal parameters of mechanical structures using only measured responses. The study deals with structural responses coupled with harmonic components amplitude and frequency modulated in a short range, a common combination for mechanical systems with engines and other rotating machines in operation. These harmonic components generate misleading data interpreted erroneously by the classical methods used in OMA. The present work attempts to differentiate maxima in spectra stemming from harmonic components and structural modes. The detection method proposed is based on the so-called Optimized Spectral Kurtosis and compared with others definitions of Spectral Kurtosis described in the literature. After a parametric study of the method, a critical study is performed on numerical simulations and then on an experimental structure in operation in order to assess the method's performance.
Advanced spectral analysis of ionospheric waves observed with sparse arrays
Helmboldt, Joseph
2014-01-01
This paper presents a case study from a single, six-hour observing period to illustrate the application of techniques developed for interferometric radio telescopes to the spectral analysis of observations of ionospheric fluctuations with sparse arrays. We have adapted the deconvolution methods used for making high dynamic range images of cosmic sources with radio arrays to making comparably high dynamic range maps of spectral power of wavelike ionospheric phenomena. In the example presented here, we have used observations of the total electron content (TEC) gradient derived from Very Large Array (VLA) observations of synchrotron emission from two galaxy clusters at 330 MHz as well as GPS-based TEC measurements from a sparse array of 33 receivers located within New Mexico near the VLA. We show that these techniques provide a significant improvement in signal to noise (S/N) of detected wavelike structures by correcting for both measurement inaccuracies and wavefront distortions. This is especially true for the...
A Spectral Analysis of Laser Induced Fluorescence of Iodine
Bayram, S B
2015-01-01
When optically excited, iodine absorbs in the 490- to 650-nm visible region of the spectrum and, after radiative relaxation, it displays an emission spectrum of discrete vibrational bands at moderate resolution. This makes laser-induced fuorescence spectrum of molecular iodine especially suitable to study the energy structure of homonuclear diatomic molecules at room temperature. In this spirit, we present a rather straightforward and inexpensive experimental setup and the associated spectral analysis which provides an excellent exercise of applied quantum mechanics fit for advanced laboratory courses. The students would be required to assign spectral lines, fill a Deslandres table, process the data to estimate the harmonic and anharmonic characteristics of the ground vibronic state involved in the radiative transitions, and thenceforth calculate a set of molecular constants and discuss a model of molecular vibrator.
Spectral analysis of SMC X-2 during its 2015 outburst
La Palombara, N; Pintore, F; Esposito, P; Mereghetti, S; Tiengo, A
2016-01-01
We report on the results of Swift and XMM-Newton observations of SMC X-2 during its last outburst in 2015 October, the first one since 2000. The source reached a very high luminosity ($L \\sim 10^{38}$ erg s$^{-1}$), which allowed us to perform a detailed analysis of its timing and spectral properties. We obtained a pulse period $P_{\\rm spin}$ = 2.372267(5) s and a characterization of the pulse profile also at low energies. The main spectral component is a hard ($\\Gamma \\simeq 0$) power-law model with an exponential cut-off, but at low energies we detected also a soft (with kT $\\simeq$ 0.15 keV) thermal component. Several emission lines can be observed at various energies. The identification of these features with the transition lines of highly ionized N, O, Ne, Si, and Fe suggests the presence of photoionized matter around the accreting source.
Voyager 2 solar plasma and magnetic field spectral analysis for intermediate data sparsity
Gallana, Luca; Iovieno, Michele; Fosson, Sophie M; Magli, Enrico; Opher, Merav; Richardson, John D; Tordella, Daniela
2015-01-01
The Voyager probes are the furthest, still active, spacecraft ever launched from Earth. During their 38-year trip, they have collected data regarding solar wind properties (such as the plasma velocity and magnetic field intensity). Unfortunately, a complete time evolution of the measured physical quantities is not available. The time series contains many gaps which increase in frequency and duration at larger distances. The aim of this work is to perform a spectral and statistical analysis of the solar wind plasma velocity and magnetic field using Voyager 2 data measured in 1979, when the gaps/signal ratio is of order of unity. This analysis is achieved using four different data reconstruction techniques: averages on linearly interpolated subsets, correlation of linearly interpolated data, compressed sensing spectral estimation, and maximum likelihood data reconstruction. With five frequency decades, the spectra we obtained have the largest frequency range ever computed at 5 astronomical units from the Sun; s...
García-Jerez, Antonio; Piña-Flores, José; Sánchez-Sesma, Francisco J.; Luzón, Francisco; Perton, Mathieu
2016-12-01
During a quarter of a century, the main characteristics of the horizontal-to-vertical spectral ratio of ambient noise HVSRN have been extensively used for site effect assessment. In spite of the uncertainties about the optimum theoretical model to describe these observations, over the last decade several schemes for inversion of the full HVSRN curve for near surface surveying have been developed. In this work, a computer code for forward calculation of H/V spectra based on the diffuse field assumption (DFA) is presented and tested. It takes advantage of the recently stated connection between the HVSRN and the elastodynamic Green's function which arises from the ambient noise interferometry theory. The algorithm allows for (1) a natural calculation of the Green's functions imaginary parts by using suitable contour integrals in the complex wavenumber plane, and (2) separate calculation of the contributions of Rayleigh, Love, P-SV and SH waves as well. The stability of the algorithm at high frequencies is preserved by means of an adaptation of the Wang's orthonormalization method to the calculation of dispersion curves, surface-waves medium responses and contributions of body waves. This code has been combined with a variety of inversion methods to make up a powerful tool for passive seismic surveying.
García-Jerez, Antonio; Sánchez-Sesma, Francisco J; Luzón, Francisco; Perton, Mathieu
2016-01-01
During a quarter of a century, the main characteristics of the horizontal-to-vertical spectral ratio of ambient noise HVSRN have been extensively used for site effect assessment. In spite of the uncertainties about the optimum theoretical model to describe these observations, several schemes for inversion of the full HVSRN curve for near surface surveying have been developed over the last decade. In this work, a computer code for forward calculation of H/V spectra based on the diffuse field assumption (DFA) is presented and tested.It takes advantage of the recently stated connection between the HVSRN and the elastodynamic Green's function which arises from the ambient noise interferometry theory. The algorithm allows for (1) a natural calculation of the Green's functions imaginary parts by using suitable contour integrals in the complex wavenumber plane, and (2) separate calculation of the contributions of Rayleigh, Love, P-SV and SH waves as well. The stability of the algorithm at high frequencies is preserv...
Subpixel measurement of mangrove canopy closure via spectral mixture analysis
Minhe JI; Jing FENG
2011-01-01
Canopy closure can vary spatially within a remotely sensed image pixel,but Boolean logic inherent in traditional classification methods only works at the wholepixel level.This study attempted to decompose mangrove closure information from spectrally-mixed pixels through spectral mixture analysis (SMA) for coastal wetland management.Endmembers of different surface categories were established through signature selection and training,and memberships of a pixel with respect to the surface categories were determined via a spectral mixture model.A case study involving DigitalGlobe's Quickbird highresolution multispectral imagery of Beilun Estuary,China was used to demonstrate this approach.Mangrove canopy closure was first quantified as percent coverage through the model and then further grouped into eight ordinal categories.The model results were verified using Quickbird panchromatic data from the same acquisition.An overall accuracy of 84.4% (Kappa = 0.825) was achieved,indicating good application potential of the approach in coastal resource inventory and ecosystem management.
Effective dielectric constants and spectral density analysis of plasmonic nanocomposites
Lu, Jin You; Raza, Aikifa; Fang, Nicholas X.; Chen, Gang; Zhang, TieJun
2016-10-01
Cermet or ceramic-metal composite coatings promise great potentials in light harvesting, but the complicated composite structure at the nanoscale induces a design challenge to predict their optical properties. We find that the effective dielectric constants of nanocomposites predicted by finite-difference-time-domain (FDTD) simulation results match those of different classical effective medium theories in their respective validity range. However, a precise prediction of the fabricated nanocomposite properties for different filling factors is very challenging. In this work, we extract the spectral density functions in the Bergman representation from the analytical models, numerical simulations, and experimental data of plasmonic nanocomposites. The spectral density functions, which only depend on geometry of the nanocomposite material, provide a unique measure on the contribution of individual and percolated particles inside the nanocomposite. According to the spectral density analysis of measured dielectric constants, the material properties of nanocomposites fabricated by the co-sputtering approach are dominated by electromagnetic interaction among individual metallic particles. While in the case of the nanocomposites fabricated by the multilayer thin film approach, the material properties are dominated by percolated metallic particles inside the dielectric host, as indicated by our FDTD simulation results. This understanding provides new physical insight into the interaction between light and plasmonic nanocomposites.
Coefficient of variation spectral analysis: An application to underwater acoustics
Herstein, P. D.; Laplante, R. F.
1983-05-01
Acoustic noise in the ocean is often described in terms of its power spectral density. Just as in other media, this noise consists of both narrowband and broadband frequency components. A major problem in the analysis of power spectral density measurements is distinguishing between narrowband spectral components of interest and contaminating narrowband components. In this paper, the use of coefficient of variation (Cv) spectrum is examined as an adjunct to the conventional power spectrum to distinguish narrowband components of interest from contaminating components. The theory of the Cv is presented. Coefficients for several classical input distributions are developed. It is shown that Cv spectra can be easily implemented as an adjunct procedure during the computation of the ensemble of averaged power spectra. Power and Cv spectra derived from actual at-sea sonobuoy measurements of deep ocean ambient noise separate narrowband components from narrowband lines of interest in the ensemble of averaged power spectra, these acoustic components of interest can be distinguished in the Cv spectra.
Spectral analysis in thin tubes with axial heterogeneities
Ferreira, Rita
2015-01-01
In this paper, we present the 3D-1D asymptotic analysis of the Dirichlet spectral problem associated with an elliptic operator with axial periodic heterogeneities. We extend to the 3D-1D case previous 3D-2D results (see [10]) and we analyze the special case where the scale of thickness is much smaller than the scale of the heterogeneities and the planar coefficient has a unique global minimum in the periodic cell. These results are of great relevance in the comprehension of the wave propagation in nanowires showing axial heterogeneities (see [17]).
Incorporating Endmember Variability into Spectral Mixture Analysis Through Endmember Bundles
Bateson, C. Ann; Asner, Gregory P.; Wessman, Carol A.
1998-01-01
Variation in canopy structure and biochemistry induces a concomitant variation in the top-of-canopy spectral reflectance of a vegetation type. Hence, the use of a single endmember spectrum to track the fractional abundance of a given vegetation cover in a hyperspectral image may result in fractions with considerable error. One solution to the problem of endmember variability is to increase the number of endmembers used in a spectral mixture analysis of the image. For example, there could be several tree endmembers in the analysis because of differences in leaf area index (LAI) and multiple scatterings between leaves and stems. However, it is often difficult in terms of computer or human interaction time to select more than six or seven endmembers and any non-removable noise, as well as the number of uncorrelated bands in the image, limits the number of endmembers that can be discriminated. Moreover, as endmembers proliferate, their interpretation becomes increasingly difficult and often applications simply need the aerial fractions of a few land cover components which comprise most of the scene. In order to incorporate endmember variability into spectral mixture analysis, we propose representing a landscape component type not with one endmember spectrum but with a set or bundle of spectra, each of which is feasible as the spectrum of an instance of the component (e.g., in the case of a tree component, each spectrum could reasonably be the spectral reflectance of a tree canopy). These endmember bundles can be used with nonlinear optimization algorithms to find upper and lower bounds on endmember fractions. This approach to endmember variability naturally evolved from previous work in deriving endmembers from the data itself by fitting a triangle, tetrahedron or, more generally, a simplex to the data cloud reduced in dimension by a principal component analysis. Conceptually, endmember variability could make it difficult to find a simplex that both surrounds the data
Schwarzschild scalar wigs: spectral analysis and late time behavior
Barranco, Juan; Degollado, Juan Carlos; Diez-Tejedor, Alberto; Megevand, Miguel; Alcubierre, Miguel; Nunez, Dario; Sarbach, Olivier
2013-01-01
Using the Green's function representation technique, the late time behavior of localized scalar field distributions on Schwarzschild spacetimes is studied. Assuming arbitrary initial data we perform a spectral analysis, computing the amplitude of each excited quasi-bound mode without the necessity of performing dynamical evolutions. The resulting superposition of modes is compared with a traditional numerical evolution with excellent agreement; therefore, we have an efficient way to determine final black hole wigs. The astrophysical relevance of the quasi-bound modes is discussed in the context of scalar field dark matter models and the axiverse.
Multiphoton autofluorescence spectral analysis for fungus imaging and identification
Lin, Sung-Jan; Tan, Hsin-Yuan; Kuo, Chien-Jui; Wu, Ruei-Jr; Wang, Shiou-Han; Chen, Wei-Liang; Jee, Shiou-Hwa; Dong, Chen-Yuan
2009-07-01
We performed multiphoton imaging on fungi of medical significance. Fungal hyphae and spores of Aspergillus flavus, Micosporum gypseum, Micosoprum canis, Trichophyton rubrum, and Trichophyton tonsurans were found to be strongly autofluorescent but generate less prominent second harmonic signal. The cell wall and septum of fungal hyphae can be easily identified by autofluorescence imaging. We found that fungi of various species have distinct autofluorescence characteristics. Our result shows that the combination of multiphoton imaging and spectral analysis can be used to visualize and identify fungal species. This approach may be developed into an effective diagnostic tool for fungal identification.
Spectral analysis of the Forbush decrease of 13 July 1982
Vainikka, E.; Torsti, J. J.; Valtonen, E.; Lumme, M.; Nieminen, M.; Peltonen, J.; Arvela, H.
1985-01-01
The maximum entropy method has been applied in the spectral analysis of high-energy cosmic-ray intensity during the large Forbush event of July 13, 1982. An oscillation with period of about 2 hours and amplitude of 1 to 3% was found to be present during the decrease phase. This oscillation can be related to a similar periodicity in the magnetospheric field. However, the variation was not observed at all neutron monitor stations. In the beginning of the recovery phase, the intensity oscillated with a period of about 10 hours and amplitude of 3%.
Understanding Boswellia papyrifera tree secondary metabolites through bark spectral analysis
Girma, Atkilt; Skidmore, Andrew K.; de Bie, C. A. J. M.; Bongers, Frans
2015-07-01
Decision makers are concerned whether to tap or rest Boswellia Papyrifera trees. Tapping for the production of frankincense is known to deplete carbon reserves from the tree leading to production of less viable seeds, tree carbon starvation and ultimately tree mortality. Decision makers use traditional experience without considering the amount of metabolites stored or depleted from the stem-bark of the tree. This research was designed to come up with a non-destructive B. papyrifera tree metabolite estimation technique relevant for management using spectroscopy. The concentration of biochemicals (metabolites) found in the tree bark was estimated through spectral analysis. Initially, a random sample of 33 trees was selected, the spectra of bark measured with an Analytical Spectral Device (ASD) spectrometer. Bark samples were air dried and ground. Then, 10 g of sample was soaked in Petroleum ether to extract crude metabolites. Further chemical analysis was conducted to quantify and isolate pure metabolite compounds such as incensole acetate and boswellic acid. The crude metabolites, which relate to frankincense produce, were compared to plant properties (such as diameter and crown area) and reflectance spectra of the bark. Moreover, the extract was compared to the ASD spectra using partial least square regression technique (PLSR) and continuum removed spectral analysis. The continuum removed spectral analysis were performed, on two wavelength regions (1275-1663 and 1836-2217) identified through PLSR, using absorption features such as band depth, area, position, asymmetry and the width to characterize and find relationship with the bark extracts. The results show that tree properties such as diameter at breast height (DBH) and the crown area of untapped and healthy trees were strongly correlated to the amount of stored crude metabolites. In addition, the PLSR technique applied to the first derivative transformation of the reflectance spectrum was found to estimate the
Xiaoling Yang
2015-07-01
Full Text Available The purity of waxy corn seed is a very important index of seed quality. A novel procedure for the classification of corn seed varieties was developed based on the combined spectral, morphological, and texture features extracted from visible and near-infrared (VIS/NIR hyperspectral images. For the purpose of exploration and comparison, images of both sides of corn kernels (150 kernels of each variety were captured and analyzed. The raw spectra were preprocessed with Savitzky-Golay (SG smoothing and derivation. To reduce the dimension of spectral data, the spectral feature vectors were constructed using the successive projections algorithm (SPA. Five morphological features (area, circularity, aspect ratio, roundness, and solidity and eight texture features (energy, contrast, correlation, entropy, and their standard deviations were extracted as appearance character from every corn kernel. Support vector machines (SVM and a partial least squares–discriminant analysis (PLS-DA model were employed to build the classification models for seed varieties classification based on different groups of features. The results demonstrate that combining spectral and appearance characteristic could obtain better classification results. The recognition accuracy achieved in the SVM model (98.2% and 96.3% for germ side and endosperm side, respectively was more satisfactory than in the PLS-DA model. This procedure has the potential for use as a new method for seed purity testing.
Detection of Explosives Under Covering Soap Using THz Spectral Dynamics Analysis
Trofimov, Vyacheslav A.; Varentsova, Svetlana A.
The method of THz spectral dynamics analysis (SDA-method) is used for identification of compound media and detection of their components. We considered the examples simulating the real case of NG and TNB explosives mixed with soap in different ratio - as a sum of two signals, passed through explosive and harmless material. Our investigations showed that spectrograms of the sum of THz pulses widely differ from spectrograms and dynamics of spectral lines for pulse passed through soap. So it is possible to detect the presence of explosive in the mixture with soap even if the amplitude of the pulse from explosive is 20 times less than the amplitude of the signal from soap. Therefore, the method allows detecting and identifying explosive in compound media with high probability and can be very effective for defense and security applications.
Sánchez-Sesma, Francisco J.
2017-07-01
Microtremor H/ V spectral ratio (MHVSR) has gained popularity to assess the dominant frequency of soil sites. It requires measurement of ground motion due to seismic ambient noise at a site and a relatively simple processing. Theory asserts that the ensemble average of the autocorrelation of motion components belonging to a diffuse field at a given receiver gives the directional energy densities (DEDs) which are proportional to the imaginary parts of the Green's function components when both source and receiver are the same point and the directions of force and response coincide. Therefore, the MHVSR can be modeled as the square root of 2 × Im G 11/Im G 33, where Im G 11 and Im G 33 are the imaginary parts of Green's functions at the load point for the horizontal (sub-index 1) and vertical (sub-index 3) components, respectively. This connection has physical implications that emerge from the duality DED force and allows understanding the behavior of the MHVSR. For a given model, the imaginary parts of the Green's functions are integrals along a radial wavenumber. To deal with these integrals, we have used either the popular discrete wavenumber method or the Cauchy's residue theorem at the poles that account for surface waves normal modes giving the contributions due to Rayleigh and Love waves. For the retrieval of the velocity structure, one can minimize the weighted differences between observations and calculated values using the strategy of an inversion scheme. In this research, we used simulated annealing but other optimization techniques can be used as well. This last approach allows computing separately the contributions of different wave types. An example is presented for the mouth of Andarax River at Almería, Spain. [Figure not available: see fulltext.
The inversion of spectral ratio H/V in a layered system using the diffuse field assumption (DFA)
Piña-Flores, José; Perton, Mathieu; García-Jerez, Antonio; Carmona, Enrique; Luzón, Francisco; Molina-Villegas, Juan C.; Sánchez-Sesma, Francisco J.
2017-01-01
In order to evaluate the site effects on seismic ground motion and establish preventive measures to mitigate these effects, the dynamic characterization of sites is mandatory. Among the various geophysical tools aimed to this end, the horizontal to vertical spectral ratio (H/V) is a simple way to assess the dominant frequency of a site from seismic ambient noise. The aim of this communication is contributing to enhance the potential of this measurement with a novel method that allows extracting from the H/V the elastic properties of the subsoil, assumed here as a multilayer medium. For that purpose, we adopt the diffuse field assumption from both the experimental and the modelling perspectives. At the experimental end, the idea is to define general criteria that make the data processing closely supported by theory. On the modelling front, the challenge is to compute efficiently the imaginary part of Green's function. The Cauchy's residue theory in the horizontal wavenumber complex plane is the selected approach. This method allows both identifying the contributions of body and surface waves and computing them separately. This permits exploring the theoretical properties of the H/V under different compositions of the seismic ambient noise. This answers some questions that historically aroused and gives new insights into the H/V method. The efficient forward calculation is the prime ingredient of an inversion scheme based on both gradient and heuristic searches. The availability of efficient forward calculation of H/V allows exploring some relevant relationships between the H/V curves and the parameters. This allows generating useful criteria to speed up inversion. As in many inverse problems, the non-uniqueness issues also emerge here. A joint inversion method that considers also the dispersion curves of surface waves extracted from seismic ambient noise is presented and applied to experimental data. This joint scheme mitigates effectively the non-uniqueness.
The inversion of spectral ratio H/V in a layered system using the Diffuse Field Assumption (DFA)
Piña-Flores, José; Perton, Mathieu; García-Jerez, Antonio; Carmona, Enrique; Luzón, Francisco; Molina-Villegas, Juan C.; Sánchez-Sesma, Francisco J.
2016-11-01
In order to evaluate the site effects on seismic ground motion and establish preventive measures to mitigate these effects, the dynamic characterization of sites is mandatory. Among the various geophysical tools aimed to this end, the horizontal to vertical spectral ratio (H/V) is a simple way to assess the dominant frequency of a site from seismic ambient noise. The aim of this communication is contributing to enhance the potential of this measurement with a novel method that allows extracting from the H/V the elastic properties of the subsoil, assumed here as a multilayer medium. For that purpose, we adopt the Diffuse Field Assumption from both the experimental and the modeling perspectives. At the experimental end, the idea is to define general criteria that make the data processing closely supported by theory. On the modeling front, the challenge is to compute efficiently the imaginary part of Green's function. The Cauchy's residue theory in the horizontal wavenumber complex plane is the selected approach. This method allows both identifying the contributions of body and surface waves and computing them separately. This permits exploring the theoretical properties of the H/V under different compositions of the seismic ambient noise. This answers some questions that historically aroused and gives new insights into the H/V method. The efficient forward calculation is the prime ingredient of an inversion scheme based on both gradient and heuristic searches. The availability of efficient forward calculation of H/V allows exploring some relevant relationships between the H/V curves and the parameters. This allows generating useful criteria to speed up inversion. As in many inverse problems, the non-uniqueness issues also emerge here. A joint inversion method that considers also the dispersion curves of surface waves extracted from seismic ambient noise is presented and applied to experimental data. This joint scheme mitigates effectively the non-uniqueness.
IMF and [Na/Fe] abundance ratios from optical and NIR spectral features in early-type galaxies
La Barbera, F.; Vazdekis, A.; Ferreras, I.; Pasquali, A.; Allende Prieto, C.; Röck, B.; Aguado, D. S.; Peletier, R. F.
2017-01-01
We present a joint analysis of the four most prominent sodium-sensitive features (Na D, Na I λ8190Å, Na I λ1.14 μm, and Na I λ2.21 μm), in the optical and near-infrared spectral ranges, of two nearby, massive (σ ˜ 300 km s-1), early-type galaxies (named XSG1 and XSG2). Our analysis relies on deep Very Large Telescope/X-Shooter long-slit spectra, along with newly developed stellar population models, allowing for [Na/Fe] variations, up to ˜1.2 dex, over a wide range of age, total metallicity, and initial mass function (IMF) slope. The new models show that the response of the Na-dependent spectral indices to [Na/Fe] is stronger when the IMF is bottom heavier. For the first time, we are able to match all four Na features in the central regions of massive early-type galaxies finding an overabundance of [Na/Fe] in the range 0.5-0.7 dex and a bottom-heavy IMF. Therefore, individual abundance variations cannot be fully responsible for the trends of gravity-sensitive indices, strengthening the case towards a non-universal IMF. Given current limitations of theoretical atmosphere models, our [Na/Fe] estimates should be taken as upper limits. For XSG1, where line strengths are measured out to ˜0.8 Re, the radial trend of [Na/Fe] is similar to [α/Fe] and [C/Fe], being constant out to ˜0.5 Re, and decreasing by ˜0.2-0.3 dex at ˜0.8 Re, without any clear correlation with local metallicity. Such a result seems to be in contrast to the predicted increase of Na nucleosynthetic yields from asymptotic giant branch stars and Type II supernovae. For XSG1, the Na-inferred IMF radial profile is consistent, within the errors, with that derived from TiO features and the Wing-Ford band presented in a recent paper.
Critical ratios for structural analysis of triacylglycerols using mass spectrometry
Recent developments have finally allowed fragment behaviors using APCI-MS to be elucidated after twenty years of literature reports. Critical Ratios have been defined that correspond to various aspects of triacylglycerol (TAG) analysis, from overall degree of unsaturation to localization of fatty ac...
Simulation Modeling and Analysis of Operator-Machine Ratio
无
2007-01-01
Based on a simulation model of a semiconductor manufacturer, operator-machine ratio (OMR) analysis is made using work study and time study. Through sensitivity analysis, it is found that labor utilization decreases with the increase of lot size.Meanwhile, it is able to identify that the OMR for this company should be improved from 1∶3 to 1∶5. An application result shows that the proposed model can effectively improve the OMR by 33%.
Sanchez-Sesma, F. J.; Perton, M.; Piña, J.; Luzón, F.; Garcia-Jerez, A.; Rodriguez-Castellanos, A.
2013-12-01
It is well know the popularity of H/V spectral ratio to extract the dominant frequency of soil sites for microzonation studies (Nakamura, 1989). It is relatively easy to make measurements as only one station is needed. Despite its success, this approach had not solid theoretical basis until a proposal to link ambient noise vibrations with diffuse field theory was made (Sánchez-Sesma et al, 2011a). Based on this theory the average spectral density of a given motion of a point, also called directional energy density (Perton et al, 2009), is proportional to the imaginary part of Green function precisely at the observation point. The proportionality implies that vector components are all multiplied by the current spectral level of the diffuse illumination. Appropriate normalization is crucial to make the experimental spectral ratios closer to the theoretical counterpart. According to this theory the square of H/V is twice the ratio of ImG11 and ImG33, where ImG11 and ImG33 are the imaginary part of Green functions at the load point for horizontal and vertical components, respectively. From ImG11 it could be possible through Fourier analysis to extract pseudo reflections and thus constrain the inversion of soil profile. We propose to assess ImG11 removing the influence of illumination spectrum using the H/V spectral ratio and an estimate of ImG33 (obtained from a priori model) by means of ImG11=0.5(H/V)2*ImG33. It has been found that ImG33 is less sensitive to details of stratigraphy. In fact, the most relevant property is the Poisson ratio of the uppermost layer which controls the slope in high frequency (Sánchez-Sesma et al, 2011b). Pseudo-reflection seismograms are thus obtained from Fourier transform, back to time domain, of i{ImG11-ImG11HSS}, where ImG11HSS is the imaginary part of Green functions at the load point for horizontal load at the surface of a half-space with the properties of the uppermost layer. With the obtained model ImG33 can be updated and the
无
2005-01-01
The influence of major cultural practices including different nitrogen application rates, population densities, transplanting leaf ages of seedling, and water regimes on rice canopy spectral reflectance was investigated. Results showed that increased nitrogen rates, water regimes and population densities and decreased seedling ages could enhance reflectance at NIR (near infrared) bands and reduce reflectance at visible bands. Using reflectance of green, red and NIR band and ratio index of 810-560 nm could distinguish the different type of rice by fuzzy cluster analysis.
Efficient geometric rectification techniques for spectral analysis algorithm
Chang, C. Y.; Pang, S. S.; Curlander, J. C.
1992-01-01
The spectral analysis algorithm is a viable technique for processing synthetic aperture radar (SAR) data in near real time throughput rates by trading the image resolution. One major challenge of the spectral analysis algorithm is that the output image, often referred to as the range-Doppler image, is represented in the iso-range and iso-Doppler lines, a curved grid format. This phenomenon is known to be the fanshape effect. Therefore, resampling is required to convert the range-Doppler image into a rectangular grid format before the individual images can be overlaid together to form seamless multi-look strip imagery. An efficient algorithm for geometric rectification of the range-Doppler image is presented. The proposed algorithm, realized in two one-dimensional resampling steps, takes into consideration the fanshape phenomenon of the range-Doppler image as well as the high squint angle and updates of the cross-track and along-track Doppler parameters. No ground reference points are required.
Spectral analysis for automated exploration and sample acquisition
Eberlein, Susan; Yates, Gigi
1992-01-01
Future space exploration missions will rely heavily on the use of complex instrument data for determining the geologic, chemical, and elemental character of planetary surfaces. One important instrument is the imaging spectrometer, which collects complete images in multiple discrete wavelengths in the visible and infrared regions of the spectrum. Extensive computational effort is required to extract information from such high-dimensional data. A hierarchical classification scheme allows multispectral data to be analyzed for purposes of mineral classification while limiting the overall computational requirements. The hierarchical classifier exploits the tunability of a new type of imaging spectrometer which is based on an acousto-optic tunable filter. This spectrometer collects a complete image in each wavelength passband without spatial scanning. It may be programmed to scan through a range of wavelengths or to collect only specific bands for data analysis. Spectral classification activities employ artificial neural networks, trained to recognize a number of mineral classes. Analysis of the trained networks has proven useful in determining which subsets of spectral bands should be employed at each step of the hierarchical classifier. The network classifiers are capable of recognizing all mineral types which were included in the training set. In addition, the major components of many mineral mixtures can also be recognized. This capability may prove useful for a system designed to evaluate data in a strange environment where details of the mineral composition are not known in advance.
MAC to VAX Connectivity: Heartrate Spectral Analysis System
Rahman, Hasan H.; Faruque, Monazer
1993-01-01
The heart rate Spectral Analysis System (SAS) acquires and analyzes, in real-time, the Space Shuttle onboard electrocardiograph (EKG) experiment signals, calculates the heartrate, and applies a Fast Fourier Transformation (FFT) to the heart rate. The system also calculates other statistical parameters such as the 'mean heart rate' over specific time period and heart rate histogram. This SAS is used by NASA Principal Investigators as a research tool to determine the effects of weightlessness on the human cardiovascular system. This is also used to determine if Lower Body Negative Pressure (LBNP) is an effective countermeasure to the orthostatic intolerance experienced by astronauts upon return to normal gravity. In microgravity, astronauts perform the LBNP experiment in the mid deck of the Space Shuttle. The experiment data are downlinked by the orbiter telemetry system, then processed and analyzed in real-time by the integrated Life Sciences Data Acquisition (LSDS) - Spectral Analysis System. The data system is integrated within the framework of two different computer systems, VAX and Macintosh (Mac), using the networking infrastructure to assist the investigators in further understanding the most complex machine on Earth--the human body.
USING RATIO METHOD IN THE TOURISM INDUSTRY PERFORMANCE ANALYSIS
Andone Diana
2015-07-01
Full Text Available Ratios represent useful analysis instruments that synthetize a large volume of data in an easier to understand, interpret and compare form. At the same time, they show certain limits that have to be analyzed for each case. When comparing ratios from different periods, one has to take into account the circumstances in which the company performs its activity, as well as the effect of certain changes in the financial reporting, such as : change in the economic circumstances, the productive process, the different production lines or the geographical target markets.
Spectral line removal in the LIGO Data Analysis System (LDAS)
Searle, Antony C; Scott, Susan M; McClelland, David E [Department of Physics, Faculty of Science, Australian National University, Canberra ACT 0200 (Australia)
2003-09-07
High power in narrow frequency bands, spectral lines, are a feature of an interferometric gravitational wave detector's output. Some lines are coherent between interferometers, in particular, the 2 km and 4 km LIGO Hanford instruments. This is of concern to data analysis techniques, such as the stochastic background search, that use correlations between instruments to detect gravitational radiation. Several techniques of 'line removal' have been proposed. Where a line is attributable to a measurable environmental disturbance, a simple linear model may be fitted to predict, and subsequently subtract away, that line. This technique has been implemented (as the command oelslr) in the LIGO Data Analysis System (LDAS). We demonstrate its application to LIGO S1 data.
Software for the Spectral Analysis of Hot Stars
Rauch, Thomas; Stampa, Ulrike; Demleitner, Markus; Koesterke, Lars
2009-01-01
In a collaboration of the German Astrophysical Virtual Observatory (GAVO) and AstroGrid-D, the German Astronomy Community Grid (GACG), we provide a VO service for the access and the calculation of stellar synthetic energy distributions (SEDs) based on static as well as expanding non-LTE model atmospheres. At three levels, a VO user may directly compare observed and theoretical SEDs: The easiest and fastest way is to use pre-calculated SEDs from the GAVO database. For individual objects, grids of model atmospheres and SEDs can be calculated on the compute resources of AstroGrid-D within reasonable wallclock time. Experienced VO users may even create own atomic-data files for a more detailed analysis. This VO service opens also the perspective for a new approach to an automated spectral analysis of a large number of observations, e.g. provided by multi-object spectrographs.
Spectral Line Removal in the LIGO Data Analysis System (LDAS)
Searle, A C; McClelland, D E; Searle, Antony C.; Scott, Susan M.; Clelland, David E. Mc
2003-01-01
High power in narrow frequency bands, spectral lines, are a feature of an interferometric gravitational wave detector's output. Some lines are coherent between interferometers, in particular, the 2 km and 4 km LIGO Hanford instruments. This is of concern to data analysis techniques, such as the stochastic background search, that use correlations between instruments to detect gravitational radiation. Several techniques of `line removal' have been proposed. Where a line is attributable to a measurable environmental disturbance, a simple linear model may be fitted to predict, and subsequently subtract away, that line. This technique has been implemented (as the command oelslr) in the LIGO Data Analysis System (LDAS). We demonstrate its application to LIGO S1 data.
Wada, N.; Kawakata, H.; Murakami, O.; Doi, I.; Yoshimitsu, N.; Nakatani, M.; Yabe, Y.; Naoi, M. M.; Miyakawa, K.; Miyake, H.; Ide, S.; Igarashi, T.; Morema, G.; Pinder, E.; Ogasawara, H.
2011-12-01
Scaling relationship between corner frequencies, fc, and seismic moments, Mo is an important clue to understand the seismic source characteristics. Aki (1967) showed that Mo is proportional to fc-3 for large earthquakes (cubic law). Iio (1986) claimed breakdown of the cubic law between fc and Mo for smaller earthquakes (Mw 4) by using high quality data observed at a deep borehole (Abercrombie, 1995; Ogasawara et al., 2001; Hiramatsu et al., 2002; Yamada et al., 2007). In order to clarify the scaling relationship for smaller earthquakes (Mw < -1), we analyzed ultra micro earthquakes using very high sampling records (48 kHz) of borehole seismometers installed within a hard rock at the Mponeng mine in South Africa. We used 4 tri-axial accelerometers of three-component that have a flat response up to 25 kHz. They were installed to be 10 to 30 meters apart from each other at 3,300 meters deep. During the period from 2008/10/14 to 2008/10/30 (17 days), 8,927 events were recorded. We estimated fc and Mo for 60 events (-3 < Mw < -1) within 200 meters from the seismometers. Assuming the Brune's source model, we estimated fc and Mo from spectral ratios. Common practice is using direct waves from adjacent events. However, there were only 5 event pairs with the distance between them less than 20 meters and Mw difference over one. In addition, the observation array is very small (radius less than 30 m), which means that effects of directivity and radiation pattern on direct waves are similar at all stations. Hence, we used spectral ratio of coda waves, since these effects are averaged and will be effectively reduced (Mayeda et al., 2007; Somei et al., 2010). Coda analysis was attempted only for relatively large 20 events (we call "coda events" hereafter) that have coda energy large enough for analysis. The results agree with those of the direct S-wave analysis for the same events, though the latter showed more scattering in fc-Mo trend. So, we combine the results from the both
Spectral Analysis Related to Bare-Metal and Drug-Eluting Coronary Stent Implantation
Silva, Rose Mary Ferreira Lisboa da, E-mail: roselisboa@cardiol.br [Faculdade de Medicina da UFMG, Divinópolis, MG (Brazil); Silva, Carlos Augusto Bueno [Faculdade de Medicina da UFMG, Divinópolis, MG (Brazil); Belo Horizonte, Hospital São João de Deus, Divinópolis, MG (Brazil); Greco, Otaviano José [Belo Horizonte, Hospital São João de Deus, Divinópolis, MG (Brazil); Moreira, Maria da Consolação Vieira [Faculdade de Medicina da UFMG, Divinópolis, MG (Brazil)
2014-08-15
The autonomic nervous system plays a central role in cardiovascular regulation; sympathetic activation occurs during myocardial ischemia. To assess the spectral analysis of heart rate variability during stent implantation, comparing the types of stent. This study assessed 61 patients (mean age, 64.0 years; 35 men) with ischemic heart disease and indication for stenting. Stent implantation was performed under Holter monitoring to record the spectral analysis of heart rate variability (Fourier transform), measuring the low-frequency (LF) and high-frequency (HF) components, and the LF/HF ratio before and during the procedure. Bare-metal stent was implanted in 34 patients, while the others received drug-eluting stents. The right coronary artery was approached in 21 patients, the left anterior descending, in 28, and the circumflex, in 9. As compared with the pre-stenting period, all patients showed an increase in LF and HF during stent implantation (658 versus 185 ms2, p = 0.00; 322 versus 121, p = 0.00, respectively), with no change in LF/HF. During stent implantation, LF was 864 ms2 in patients with bare-metal stents, and 398 ms2 in those with drug-eluting stents (p = 0.00). The spectral analysis of heart rate variability showed no association with diabetes mellitus, family history, clinical presentation, beta-blockers, age, and vessel or its segment. Stent implantation resulted in concomitant sympathetic and vagal activations. Diabetes mellitus, use of beta-blockers, and the vessel approached showed no influence on the spectral analysis of heart rate variability. Sympathetic activation was lower during the implantation of drug-eluting stents.
Power spectral analysis of cardiovascular variability in patients at risk for sudden cardiac death.
Malliani, A; Lombardi, F; Pagani, M; Cerutti, S
1994-03-01
The time series of successive heart periods present important variations around its mean value, determining the phenomenon of heart rate variability (HRV), assessed with both time and frequency domain approaches. A low standard deviation of the heart period (a time domain index of HRV) is a powerful prognostic indicator of sudden coronary death in patients recovering from acute myocardial infarction. Spectral analysis of HRV usually demonstrates two major components: indicated as LF (low frequency, approximately 0.1 Hz) and HF (high frequency, approximately 0.25 Hz). They are defined by center frequency and associated power, which is expressed in msec2 or normalized units. When assessed in normalized units, LF and HF provide quantitative indicators of neural control of the sinoatrial node. Numerous experimental and clinical studies have consistently indicated that the LF component is a marker of sympathetic modulation and HF a marker of vagal modulation; the LF/HF ratio is a synthetic index of sympathovagal balance. In the analysis of 24-hour Holter recordings of normal subjects, a circadian rhythmicity of spectral markers of sympathetic and vagal modulation is clearly present, with a sympathetic predominance during the day and a vagal predominance during the night. In patients recovering from an acute myocardial infarction, spectral analysis of HRV revealed an increased sympathetic and decreased vagal activity during early convalescence, and a return to their normal balance by 6 to 12 months. A clear increase of LF was also evident in patients studied within a few hours of the onset of symptoms related to an acute myocardial infarction, independent of its location. Similarly, LF increased during transient myocardial ischemia. An increase in markers of sympathetic activity has also been observed prior to episodes of malignant arrhythmias. Spectral analysis of HRV could help in the understanding of the role of abnormal neural mechanisms in sudden coronary death
Spectral Analysis Related to Bare-Metal and Drug-Eluting Coronary Stent Implantation
Rose Mary Ferreira Lisboa da Silva
2014-08-01
Full Text Available Background: The autonomic nervous system plays a central role in cardiovascular regulation; sympathetic activation occurs during myocardial ischemia. Objective: To assess the spectral analysis of heart rate variability during stent implantation, comparing the types of stent. Methods: This study assessed 61 patients (mean age, 64.0 years; 35 men with ischemic heart disease and indication for stenting. Stent implantation was performed under Holter monitoring to record the spectral analysis of heart rate variability (Fourier transform, measuring the low-frequency (LF and high-frequency (HF components, and the LF/HF ratio before and during the procedure. Results: Bare-metal stent was implanted in 34 patients, while the others received drug-eluting stents. The right coronary artery was approached in 21 patients, the left anterior descending, in 28, and the circumflex, in 9. As compared with the pre-stenting period, all patients showed an increase in LF and HF during stent implantation (658 versus 185 ms2, p = 0.00; 322 versus 121, p = 0.00, respectively, with no change in LF/HF. During stent implantation, LF was 864 ms2 in patients with bare-metal stents, and 398 ms2 in those with drug-eluting stents (p = 0.00. The spectral analysis of heart rate variability showed no association with diabetes mellitus, family history, clinical presentation, beta-blockers, age, and vessel or its segment. Conclusions: Stent implantation resulted in concomitant sympathetic and vagal activations. Diabetes mellitus, use of beta-blockers, and the vessel approached showed no influence on the spectral analysis of heart rate variability. Sympathetic activation was lower during the implantation of drug-eluting stents.
Ribou, A.-C.; Vigo, J.; Salmon, J.-M.
2002-12-01
Measuring intracellular concentrations of ions (H+, Ca2+, Mg2+) is one of the challenges of modern cell biology. Fluorescence techniques can be used for this purpose since they are noninvasive, specific, and in general sensitive enough to require only low concentrations of the probes. In this paper, we describe two methods to measure pH by fluorescence spectroscopy and a way to extend the measurement to living cells. We use the fluorescent probe, C-SNARF-1, which exhibits a spectral shift of 45 nm upon proton binding. The two-wavelength-ratio method is applied to the determination of an unknown pH in aqueous solution. The whole-spectrum-resolution method is used for the same solution for comparison and then applied on a prerecorded spectrum of a suspension of living cells. The methods described here have been adapted for laboratory classes of undergraduate students. The lab employs experimental fluorescence techniques and computational data analysis that account for the fluorescence of cellular flavoproteins. The pedagogic purpose of the experimental design is to introduce students to the concepts, equations, and validity of both methods. In addition, skills in record keeping and data analysis using Microsoft Excel Solver are developed.
Murphy, Peter J
2008-03-01
The harmonics-to-noise ratio (HNR) of the voiced speech signal has implicitly been used to infer information regarding the turbulent noise level at the glottis. However, two problems exist for inferring glottal noise attributes from the HNR of the speech wave form: (i) the measure is fundamental frequency (f0) dependent for equal levels of glottal noise, and (ii) any deviation from signal periodicity affects the ratio, not just turbulent noise. An alternative harmonics-to-noise ratio formulation [glottal related HNR (GHNR\\')] is proposed to overcome the former problem. In GHNR\\' a mean over the spectral range of interest of the HNRs at specific harmonic\\/between-harmonic frequencies (expressed in linear scale) is calculated. For the latter issue [(ii)] two spectral tilt measures are shown, using synthesis data, to be sensitive to glottal noise while at the same time being comparatively insensitive to other glottal aperiodicities. The theoretical development predicts that the spectral tilt measures reduce as noise levels increase. A conventional HNR estimator, GHNR\\' and two spectral tilt measures are applied to a data set of 13 pathological and 12 normal voice samples. One of the tilt measures and GHNR\\' are shown to provide statistically significant differentiating power over a conventional HNR estimator.
Bayesian Spectral Analysis of Metal Abandance Deficient Stars
Sourlas, E; Kashyap, V L; Drake, J; Pease, D; Sourlas, Epaminondas; Dyk, David van; Kashyap, Vinay; Drake, Jeremy; Pease, Deron
2002-01-01
Metallicity can be measured by analyzing the spectra in the X-ray region and comparing the flux in spectral lines to the flux in the underlying Bremsstrahlung continuum. In this paper we propose new Bayesian methods which directly model the Poisson nature of the data and thus are expected to exhibit improved sampling properties. Our model also accounts for the Poisson nature of background contamination of the observations, image blurring due to instrument response, and the absorption of photons in space. The resulting highly structured hierarchical model is fit using the Gibbs sampler, data augmentation and Metropolis-Hasting. We demonstrate our methods with the X-ray spectral analysis of several "Metal Abundance Deficient" stars. The model is designed to summarize the relative frequency of the energy of photons (X-ray or gamma-ray) arriving at a detector. Independent Poisson distributions are more appropriate to model the counts than the commonly used normal approximation. We model the high energy tail of th...
Accuracy Enhancement of Inertial Sensors Utilizing High Resolution Spectral Analysis
Michael Korenberg
2012-08-01
Full Text Available In both military and civilian applications, the inertial navigation system (INS and the global positioning system (GPS are two complementary technologies that can be integrated to provide reliable positioning and navigation information for land vehicles. The accuracy enhancement of INS sensors and the integration of INS with GPS are the subjects of widespread research. Wavelet de-noising of INS sensors has had limited success in removing the long-term (low-frequency inertial sensor errors. The primary objective of this research is to develop a novel inertial sensor accuracy enhancement technique that can remove both short-term and long-term error components from inertial sensor measurements prior to INS mechanization and INS/GPS integration. A high resolution spectral analysis technique called the fast orthogonal search (FOS algorithm is used to accurately model the low frequency range of the spectrum, which includes the vehicle motion dynamics and inertial sensor errors. FOS models the spectral components with the most energy first and uses an adaptive threshold to stop adding frequency terms when fitting a term does not reduce the mean squared error more than fitting white noise. The proposed method was developed, tested and validated through road test experiments involving both low-end tactical grade and low cost MEMS-based inertial systems. The results demonstrate that in most cases the position accuracy during GPS outages using FOS de-noised data is superior to the position accuracy using wavelet de-noising.
ANALYSIS OF CAMOUFLAGE COVER SPECTRAL CHARACTERISTICS BY IMAGING SPECTROMETER
A. Y. Kouznetsov
2016-03-01
Full Text Available Subject of Research.The paper deals with the problems of detection and identification of objects in hyperspectral imagery. The possibility of object type determination by statistical methods is demonstrated. The possibility of spectral image application for its data type identification is considered. Method. Researching was done by means of videospectral equipment for objects detection at "Fregat" substrate. The postprocessing of hyperspectral information was done with the use of math model of pattern recognition system. The vegetation indexes TCHVI (Three-Channel Vegetation Index and NDVI (Normalized Difference Vegetation Index were applied for quality control of object recognition. Neumann-Pearson criterion was offered as a tool for determination of objects differences. Main Results. We have carried out analysis of the spectral characteristics of summer-typecamouflage cover (Germany. We have calculated the density distribution of vegetation indexes. We have obtained statistical characteristics needed for creation of mathematical model for pattern recognition system. We have shown the applicability of vegetation indices for detection of summer camouflage cover on averdure background. We have presented mathematical model of object recognition based on Neumann-Pearson criterion. Practical Relevance. The results may be useful for specialists in the field of hyperspectral data processing for surface state monitoring.
Leon Vintro, L. [University Coll., Dublin (Ireland). Dept. of Experimental Phys.; Mitchell, P.I. [University Coll., Dublin (Ireland). Dept. of Experimental Phys.; Condren, O.M. [University Coll., Dublin (Ireland). Dept. of Experimental Phys.; Moran, M. [Lawrence Livermore National Lab., Livermore, CA (United States); Vives i Batlle, J. [University Coll., Dublin (Ireland). Dept. of Experimental Phys.; Sanchez-Cabeza, J.A. [Dept. de Fisica, Universidad Autonoma de Barcelona, Bellaterra (Spain)
1996-02-01
In this paper, a simple technique, based on commercially-available software developed for gamma spectra analysis (MicroSAMPO {sup trademark}), is described by which this complex multiplet can be resolved at the much lower activities typical of many environmental samples. In our approach, it is not necessary to make any alterations to the normal alpha spectrometric set-up (including energy dispersion), other than to improve collimation. The instrumental function is defined for each spectrum by fitting a modified gaussian with exponential tails to the comparatively well-resolved {sup 242}Pu ``doublet`` (used as tracer) and, if present, the {sup 238}Pu ``doublet``. The fitted peaks are used to create an energy calibration file with which, using published energy data, the positions (in channels) of the component peaks of the multiplet are predicted. These positions are not altered subsequently when MicroSAMPO`s interactive multiplet analysis facility is used to quantify the relative spectral intensities of the components. Before calculating the {sup 240}Pu/{sup 239}Pu ratio, it is advisable to correct for coincidence summing of alpha particles and conversion electrons. The technique has been applied to the determination of the {sup 240}Pu/{sup 239}Pu ratio in a set of environmental samples, most of which were supplied by IAEA-MEL under their laboratory intercomparison programme. Subsequently, replicate samples were analysed independently using thermal ionisation mass spectrometry. The agreement between the two sets of data was most satisfactory. Further validation of this deconvolution technique was provided by the good agreement between the measured alpha-emission probabilities for the component peaks in the {sup 239,240}Pu multiplet and published values. (orig.).
Wavelength conversion based spectral imaging
Dam, Jeppe Seidelin
There has been a strong, application driven development of Si-based cameras and spectrometers for imaging and spectral analysis of light in the visible and near infrared spectral range. This has resulted in very efficient devices, with high quantum efficiency, good signal to noise ratio and high...... resolution for this spectral region. Today, an increasing number of applications exists outside the spectral region covered by Si-based devices, e.g. within cleantech, medical or food imaging. We present a technology based on wavelength conversion which will extend the spectral coverage of state of the art...... visible or near infrared cameras and spectrometers to include other spectral regions of interest....
Aeroelastic stability analysis of high aspect ratio aircraft wings
Banerjee, J. R.; Liu, X.; Kassem, H. I.
2014-01-01
Free vibration and flutter analyses of two types of high aspect ratio aircraft wings are presented. The wing is idealised as an assembly of bending-torsion coupled beams using the dynamic stiffness method leading to a nonlinear eigenvalue problem. This problem is solved using the Wattrick-Williams algorithm yielding natural frequencies and mode shapes. The flutter analysis is carried out using the normal mode method in conjunction with generalised coordinates and two-dimensional unsteady aero...
Jurdziak, L.
1992-08-01
Discusses the basic financial ratios used to assess the financial standing of a mining enterprise: liquidity, leverage/gearing, activity and profitability ratios, cash flow to the current portion of long-term-debt ratio, etc. It is recommended that for mining enterprises, being high risk firms, the latter ratio be over 0.33:1 (the produced cash flow should cover the total debts in less than three years). The method described makes use of the ratio of various items of an annual balance in order to assess the value and credit worthiness of a mining enterprise. The possibility of a take-over, and investment risk are also evaluated. 11 refs.
Spectral reflectance of surface soils - A statistical analysis
Crouse, K. R.; Henninger, D. L.; Thompson, D. R.
1983-01-01
The relationship of the physical and chemical properties of soils to their spectral reflectance as measured at six wavebands of Thematic Mapper (TM) aboard NASA's Landsat-4 satellite was examined. The results of performing regressions of over 20 soil properties on the six TM bands indicated that organic matter, water, clay, cation exchange capacity, and calcium were the properties most readily predicted from TM data. The middle infrared bands, bands 5 and 7, were the best bands for predicting soil properties, and the near infrared band, band 4, was nearly as good. Clustering 234 soil samples on the TM bands and characterizing the clusters on the basis of soil properties revealed several clear relationships between properties and reflectance. Discriminant analysis found organic matter, fine sand, base saturation, sand, extractable acidity, and water to be significant in discriminating among clusters.
Spectral analysis methods for vehicle interior vibro-acoustics identification
Hosseini Fouladi, Mohammad; Nor, Mohd. Jailani Mohd.; Ariffin, Ahmad Kamal
2009-02-01
Noise has various effects on comfort, performance and health of human. Sound are analysed by human brain based on the frequencies and amplitudes. In a dynamic system, transmission of sound and vibrations depend on frequency and direction of the input motion and characteristics of the output. It is imperative that automotive manufacturers invest a lot of effort and money to improve and enhance the vibro-acoustics performance of their products. The enhancement effort may be very difficult and time-consuming if one relies only on 'trial and error' method without prior knowledge about the sources itself. Complex noise inside a vehicle cabin originated from various sources and travel through many pathways. First stage of sound quality refinement is to find the source. It is vital for automotive engineers to identify the dominant noise sources such as engine noise, exhaust noise and noise due to vibration transmission inside of vehicle. The purpose of this paper is to find the vibro-acoustical sources of noise in a passenger vehicle compartment. The implementation of spectral analysis method is much faster than the 'trial and error' methods in which, parts should be separated to measure the transfer functions. Also by using spectral analysis method, signals can be recorded in real operational conditions which conduce to more consistent results. A multi-channel analyser is utilised to measure and record the vibro-acoustical signals. Computational algorithms are also employed to identify contribution of various sources towards the measured interior signal. These achievements can be utilised to detect, control and optimise interior noise performance of road transport vehicles.
Jørgensen, Søren; Dau, Torsten
2011-01-01
rarely been evaluated perceptually in terms of speech intelligibility. This study analyzed the effects of the spectral subtraction strategy proposed by Berouti at al. [ICASSP 4 (1979), 208-211] on the speech recognition threshold (SRT) obtained with sentences presented in stationary speech-shaped noise....... The SRT was measured in five normal-hearing listeners in six conditions of spectral subtraction. The results showed an increase of the SRT after processing, i.e. a decreased speech intelligibility, in contrast to what is predicted by the Speech Transmission Index (STI). Here, another approach is proposed......, denoted the speech-based envelope power spectrum model (sEPSM) which predicts the intelligibility based on the signal-to-noise ratio in the envelope domain. In contrast to the STI, the sEPSM is sensitive to the increased amount of the noise envelope power as a consequence of the spectral subtraction...
Jørgensen, Søren; Dau, Torsten
2011-01-01
. The SRT was measured in five normal-hearing listeners in six conditions of spectral subtraction. The results showed an increase of the SRT after processing, i.e. a decreased speech intelligibility, in contrast to what is predicted by the Speech Transmission Index (STI). Here, another approach is proposed...... rarely been evaluated perceptually in terms of speech intelligibility. This study analyzed the effects of the spectral subtraction strategy proposed by Berouti at al. [ICASSP 4 (1979), 208-211] on the speech recognition threshold (SRT) obtained with sentences presented in stationary speech-shaped noise......, denoted the speech-based envelope power spectrum model (sEPSM) which predicts the intelligibility based on the signal-to-noise ratio in the envelope domain. In contrast to the STI, the sEPSM is sensitive to the increased amount of the noise envelope power as a consequence of the spectral subtraction...
Normalized polarization ratios for the analysis of cell polarity.
Raz Shimoni
Full Text Available The quantification and analysis of molecular localization in living cells is increasingly important for elucidating biological pathways, and new methods are rapidly emerging. The quantification of cell polarity has generated much interest recently, and ratiometric analysis of fluorescence microscopy images provides one means to quantify cell polarity. However, detection of fluorescence, and the ratiometric measurement, is likely to be sensitive to acquisition settings and image processing parameters. Using imaging of EGFP-expressing cells and computer simulations of variations in fluorescence ratios, we characterized the dependence of ratiometric measurements on processing parameters. This analysis showed that image settings alter polarization measurements; and that clustered localization is more susceptible to artifacts than homogeneous localization. To correct for such inconsistencies, we developed and validated a method for choosing the most appropriate analysis settings, and for incorporating internal controls to ensure fidelity of polarity measurements. This approach is applicable to testing polarity in all cells where the axis of polarity is known.
Scanlan, Neil W.; Schott, John R.; Brown, Scott D.
2004-01-01
Synthetic imagery has traditionally been used to support sensor design by enabling design engineers to pre-evaluate image products during the design and development stages. Increasingly exploitation analysts are looking to synthetic imagery as a way to develop and test exploitation algorithms before image data are available from new sensors. Even when sensors are available, synthetic imagery can significantly aid in algorithm development by providing a wide range of "ground truthed" images with varying illumination, atmospheric, viewing and scene conditions. One limitation of synthetic data is that the background variability is often too bland. It does not exhibit the spatial and spectral variability present in real data. In this work, four fundamentally different texture modeling algorithms will first be implemented as necessary into the Digital Imaging and Remote Sensing Image Generation (DIRSIG) model environment. Two of the models to be tested are variants of a statistical Z-Score selection model, while the remaining two involve a texture synthesis and a spectral end-member fractional abundance map approach, respectively. A detailed comparative performance analysis of each model will then be carried out on several texturally significant regions of the resultant synthetic hyperspectral imagery. The quantitative assessment of each model will utilize a set of three peformance metrics that have been derived from spatial Gray Level Co-Occurrence Matrix (GLCM) analysis, hyperspectral Signal-to-Clutter Ratio (SCR) measures, and a new concept termed the Spectral Co-Occurrence Matrix (SCM) metric which permits the simultaneous measurement of spatial and spectral texture. Previous research efforts on the validation and performance analysis of texture characterization models have been largely qualitative in nature based on conducting visual inspections of synthetic textures in order to judge the degree of similarity to the original sample texture imagery. The quantitative
Chen, Q. G.; Zhu, H. H.; Xu, Y.; Lin, B.; Chen, H.
2015-08-01
A quantitative method to discriminate caries lesions for a fluorescence imaging system is proposed in this paper. The autofluorescence spectral investigation of 39 teeth samples classified by the International Caries Detection and Assessment System levels was performed at 405 nm excitation. The major differences in the different caries lesions focused on the relative spectral intensity range of 565-750 nm. The spectral parameter, defined as the ratio of wavebands at 565-750 nm to the whole spectral range, was calculated. The image component ratio R/(G + B) of color components was statistically computed by considering the spectral parameters (e.g. autofluorescence, optical filter, and spectral sensitivity) in our fluorescence color imaging system. Results showed that the spectral parameter and image component ratio presented a linear relation. Therefore, the image component ratio was graded as 1.62 to quantitatively classify sound, early decay, established decay, and severe decay tissues, respectively. Finally, the fluorescence images of caries were experimentally obtained, and the corresponding image component ratio distribution was compared with the classification result. A method to determine the numerical grades of caries using a fluorescence imaging system was proposed. This method can be applied to similar imaging systems.
Spectral analysis in ultraweak emissions of chemi- and electrochemiluminescence systems
K.Staninski; M.Kaczmarek; S.Lis; D.Komar; A.Szyczewski
2009-01-01
Investigation of ultraweak emissions in the processes of chemiluminescence,CL,and electrochemiluminesce,ECL,requires special techniques of their recording and spectral analysis.From among the hitherto proposed methods of detection of the emission spectra of these processes,that of the cut-off filter was most sensitive.The usefulness of this method in interpretation of the CL and ECL systems of the quantum fields in the range 1×10-9-1×10-11 containing ions and complexes of Eu(Ⅲ),Tb(Ⅲ) and Dy(Ⅲ) was shown.Exceptional character of the emission bands of lanthanide ions,being a result of the f-f electron transitions and in particular their low FWHM,permitted the application of the cut-off filter method to their analysis.The results obtained for CL and ECL on the basis of analysis of ultraweak emission proved to be successful in analytical applications.The systems containing Eu(Ⅲ) ions hydrated or complexed with organic ligands enabled inferring changes in the coordination sphere of the ions.
The ZH ratio Analysis of Global Seismic Data
Yano, T.; Shikato, S.; Rivera, L.; Tanimoto, T.
2007-12-01
The ZH ratio, the ratio of vertical to horizontal component of the fundamental Rayleigh wave as a function of frequency, is an alternative approach to phase/group velocity analysis for constructing the S-wave velocity structure. In this study, teleseismic Rayleigh wave data for the frequency range between 0.004Hz to 0.04Hz is used to investigate the interior structure. We have analyzed most of the GEOSCOPE network data and some IRIS GSN stations using a technique developed by Tanimoto and Rivera (2007). Stable estimates of the ZH ratios were obtained for the frequency range for most stations. We have performed the inversion of the measured ZH ratios for the structure in the crust and mantle by using nonlinear iterative scheme. The depth sensitivity kernels for inversion are numerically calculated. Depth sensitivity of the lowest frequency extends to depths beyond 500 km but the sensitivity of the overall data for the frequency band extends down to about 300km. We found that an appropriate selection of an initial model, particularly the depth of Mohorovicic discontinuity, is important for this inversion. The inversion result depends on the initial model and turned out to be non-unique. We have constructed the initial model from the CRUST 2.0. Inversion with equal weighting to each data point tends to reduce variance of certain frequency range only. Therefore, we have developed a scheme to increase weighting to data points that do not fit well after the fifth iteration. This occurs more often for low frequency range, 0.004-0.007Hz. After fitting the lower frequency region, the low velocity zone around a depth of 100km is observed under some stations such as KIP (Kipapa, Hawaii) and ATD (Arta Cave, Djibouti). We have also carried out an analysis on the resolving power of data by examining the eigenvalues-eigenvectors of the least-squares problem. Unfortunately, the normal matrix usually has 1-2 very large eigenvalues, followed by much smaller eigenvalues. The third
Turzynski, Krzysztof
2014-01-01
We calculate the scalar spectral index n_s and the tensor-to-scalar ratio r in a class of recently proposed two-field no-scale models. We show that in order to obtain correct predictions it is crucial to include in the calculations the coupling between the curvature and the isocurvature perturbations induced by the noncanonical form of the kinetic terms. This coupling enhances the curvature perturbations and suppresses the resulting tensor-to-scalar ratio to the per mille level even for values of the slow-roll parameter epsilon~0.01.
Eskişar, TuǦBA; Özyalin, Şenol; KuruoǦLU, Mehmet; Yilmaz, H. Recep
2013-02-01
Seventy-two microtremor measurements were conducted in the northern coast of İzmir Bay. The dataset has been processed using the horizontal-to-vertical spectral ratio. The fundamental period contour map obtained showed that the fundamental period at rock sites of the northern coast of İzmir Bay was between 0.15 and 0.35 s. However, the fundamental period increased towards the western direction where thick soft sediments exist, the fundamental period varied between 0.5 and 2.0 s. A soil classification map of the area was prepared based on the data estimated from SPT- N values of 25 boreholes. It is seen that major portion of the study area, including the shore line of the northern coast had SPT- N values lower than 15. The fundamental periods obtained by H/ V spectral ratio method and the periods derived from shear wave velocity data available in 11 of 25 boreholes were well-correlated. Fundamental period map obtained from H/ V spectral ratio method illustrated the characteristics of weak soil conditions and the presence of bedrock level under thick alluvial soils. Finally, microtremor investigations have proved to be an effective tool for assessment of local soil conditions in case of thick soft sediments in the northern coast of İzmir Bay.
Tuğba Eskişar; Şenol Özyalin; Mehmet Kuruoğlu; H Recep Yilmaz
2013-02-01
Seventy-two microtremor measurements were conducted in the northern coast of İzmir Bay. The dataset has been processed using the horizontal-to-vertical spectral ratio. The fundamental period contour map obtained showed that the fundamental period at rock sites of the northern coast of İzmir Bay was between 0.15 and 0.35 s. However, the fundamental period increased towards the western direction where thick soft sediments exist, the fundamental period varied between 0.5 and 2.0 s. A soil classification map of the area was prepared based on the data estimated from SPT- values of 25 boreholes. It is seen that major portion of the study area, including the shore line of the northern coast had SPT- values lower than 15. The fundamental periods obtained by H/V spectral ratio method and the periods derived from shear wave velocity data available in 11 of 25 boreholes were well-correlated. Fundamental period map obtained from H/V spectral ratio method illustrated the characteristics of weak soil conditions and the presence of bedrock level under thick alluvial soils. Finally, microtremor investigations have proved to be an effective tool for assessment of local soil conditions in case of thick soft sediments in the northern coast of İzmir Bay.
Meta-analysis of ratios of sample variances.
Prendergast, Luke A; Staudte, Robert G
2016-05-20
When conducting a meta-analysis of standardized mean differences (SMDs), it is common to use Cohen's d, or its variants, that require equal variances in the two arms of each study. While interpretation of these SMDs is simple, this alone should not be used as a justification for assuming equal variances. Until now, researchers have either used an F-test for each individual study or perhaps even conveniently ignored such tools altogether. In this paper, we propose a meta-analysis of ratios of sample variances to assess whether the equality of variances assumptions is justified prior to a meta-analysis of SMDs. Quantile-quantile plots, an omnibus test for equal variances or an overall meta-estimate of the ratio of variances can all be used to formally justify the use of less common methods when evidence of unequal variances is found. The methods in this paper are simple to implement and the validity of the approaches are reinforced by simulation studies and an application to a real data set.
李相贤; 王振; 徐亮; 高闽光; 童晶晶; 冯明春; 刘建国
2015-01-01
To study the influence of temperature change on the spectrum quantitative analysis of greenhouse gases and carbon isotope ratio,at first, the view that the quantitative analysis of greenhouse gases and δ13CO2 value was mainly determined by the absorption coefficient was analyzed theoretically, and the calculation method of the absorption coefficient was also studied. Then referring to the HITRAN database, the temperature dependence of line intensity, FWHM and absorption coefficient were studied, the results show that the effect of line intensity is stronger than the FWHM on the absorption coefficient when the pressure is constant at 1 atm while the temperature changes. At last, the temperature dependence of greenhouse gases and carbon isotope ratio quantitative analysis based on Fourier transform infrared spectroscopy (FTIR) method was confirmed through a series of experiment, and these experiments also present that the variation of carbon isotope is more serious than the greenhouse gases variation when the temperature changes, the δ13CO2 value will change 14.37‰ while the temperature changes 1 ℃. This study is the theoretical basis for the design of the temperature monitoring and controlling system of greenhouse gases and carbon isotope ration monitoring instrument based on FTIR with high-precision.%为了研究温度变化对温室气体及碳同位素比值光谱定量分析的影响，首先从理论上分析得出温室气体浓度及δ13CO2值的定量反演主要取决于吸收系数，并研究了吸收系数的计算方法。其次结合HITRAN数据库，研究了温度对线强、展宽以及吸收系数的影响规律，结果表明：压强为1 atm(1 atm=1.013×105 Pa)恒定条件下，温度变化时，吸收系数受线强变化的影响强于受展宽变化的影响。最后通过实验验证了温室气体和碳同位素比值傅里叶变换红外光谱( FTIR )反演的温度依赖关系，其中碳同位素比值受温度变化影响幅度
3D model of Campo de Dalías basement from H/V spectral ratio of ambient seismic noise
García-Jerez, Antonio; Seivane, Helena; Luzón, Francisco; Navarro, Manuel; Molina, Luis; Aranda, Carolina; Piña-Flores, José; Navarro, Francisco; Sánchez-Martos, Francisco; Vidal, Francisco; Posadas, Antonio M.; Sánchez-Sesma, Francisco J.
2017-04-01
Campo de Dalías is a large coastal plain in the southeastern mountain front of the Betic Cordillera (SE of the Iberian Peninsula), being one of the most seismically active regions of Spain. This area has a population of about 213.000 inhabitants, with a high growth rate during the last decades due to the development of intensive agricultural activities. Seismic risk assessment and hydrogeological issues are major topics of interest for this area, relaying on the knowledge of the geophysical properties of the basin. A passive seismic survey has been conducted throughout the basin. We have recorded ambient noise at 340 sites located approximately on the vertexes of a 1000 x 1000 m square grid, as well as around a set of deep boreholes reaching the Triassic basement. These broad-band records, of at least 45 minutes long each, have been analyzed by using the horizontal-to-vertical spectral ratio method (H/V). The spectral analysis shows clear H/V peaks with periods ranging from 0.3 s to 4 s, approximately, associated to relevant contrasts in S-wave velocity (Vs) at depth. Simulations based on the diffuse field approach (Sánchez-Sesma et al. 2011) show that long periods are explained by the effect of several hundred meters of soft sedimentary rocks (mainly Miocene marls). Well-developed high-frequency secondary peaks have been found in some specific zones (e.g. N of Roquetas de Mar town). Then, fundamental frequencies and basement depths at borehole sites have been fitted by means of a power law, which can be applied down to 900 - 970m. Larger depths are estimated by extrapolation. This relationship has been used to map the basement (main Vs contrast) throughout the plain. The prospected basement model describes well the main structural features of this smoothly folded region, namely, the El Ejido Synform and the Guardias Viejas Antiform, with ENE-WSW-trend. These features are shifted toward the south in comparison with Pedrera et al. (2015). The homogeneous
Deferred tax analysis and impact on firm's economic efficiency ratios
Hana Bohušová
2005-01-01
Full Text Available Category of deferred income tax is a complex topic including the whole accounting system and the income tax. Calculation method can be time-consuming and demanding a high quality system of analytical evidence and a system of valuation and demanding the high level of accountants' knowledge. The aim in the theoretical level was to analyze process of calculation and recording of deferred tax. Importance of recording of deferred tax and the impact on financial analysis ratios was analyzed. Fourteen business entities were examined. Deferred tax recording is a legal way to reduce retained earnings a to protect of its careless alocation.
Spectral Image Analysis for Measuring Ripeness of Tomatoes
Polder, G.; Heijden, van der G.W.A.M.; Young, I.T.
2002-01-01
In this study, spectral images of five ripeness stages of tomatoes have been recorded and analyzed. The electromagnetic spectrum between 396 and 736 nm was recorded in 257 bands (every 1.3 nm). Results show that spectral images offer more discriminating power than standard RGB images for measuring r
Spectral analysis based on compressive sensing in nanophotonic structures.
Wang, Zhu; Yu, Zongfu
2014-10-20
A method of spectral sensing based on compressive sensing is shown to have the potential to achieve high resolution in a compact device size. The random bases used in compressive sensing are created by the optical response of a set of different nanophotonic structures, such as photonic crystal slabs. The complex interferences in these nanostructures offer diverse spectral features suitable for compressive sensing.
Spectral Efficiency Analysis for Multicarrier Based 4G Systems
Silva, Nuno; Rahman, Muhammad Imadur; Frederiksen, Flemming Bjerge
2006-01-01
In this paper, a spectral efficiency definition is proposed. Spectral efficiency for multicarrier based multiaccess techniques, such as OFDMA, MC-CDMA and OFDMA-CDM, is analyzed. Simulations for different indoor and outdoor scenarios are carried out. Based on the simulations, we have discussed ho...
Kojima, Jun; Nguyen, Quang-Viet
2004-01-01
We present a theoretical study of the spectral interferences in the spontaneous Raman scattering spectra of major combustion products in 30-atm fuel-rich hydrogen-air flames. An effective methodology is introduced to choose an appropriate line-shape model for simulating Raman spectra in high-pressure combustion environments. The Voigt profile with the additive approximation assumption was found to provide a reasonable model of the spectral line shape for the present analysis. The rotational/vibrational Raman spectra of H2, N2, and H2O were calculated using an anharmonic-oscillator model using the latest collisional broadening coefficients. The calculated spectra were validated with data obtained in a 10-atm fuel-rich H2-air flame and showed excellent agreement. Our quantitative spectral analysis for equivalence ratios ranging from 1.5 to 5.0 revealed substantial amounts of spectral cross-talk between the rotational H2 lines and the N2 O-/Q-branch; and between the vibrational H2O(0,3) line and the vibrational H2O spectrum. We also address the temperature dependence of the spectral cross-talk and extend our analysis to include a cross-talk compensation technique that removes the nterference arising from the H2 Raman spectra onto the N2, or H2O spectra.
CUSUM control charts based on likelihood ratio for preliminary analysis
Yi DAI; Zhao-jun WANG; Chang-liang ZOU
2007-01-01
To detect and estimate a shift in either the mean and the deviation or both for the preliminary analysis, the statistical process control (SPC) tool, the control chart based on the likelihood ratio test (LRT), is the most popular method.Sullivan and woodall pointed out the test statistic lrt (n1, n2) is approximately distributed as x2 (2) as the sample size n, n1 and n2 are very large, and the value of n1 = 2, 3,..., n- 2 and that of n2 = n- n1.So it is inevitable that n1 or n2 is not large. In this paper the limit distribution of lrt(n1, n2) for fixed n1 or n2 is figured out, and the exactly analytic formulae for evaluating the expectation and the variance of the limit distribution are also obtained.In addition, the properties of the standardized likelihood ratio statistic slr(n1,n) are discussed in this paper. Although slr(n1, n) contains the most important information, slr(i, n)(i ≠ n1) also contains lots of information. The cumulative sum (CUSUM) control chart can obtain more information in this condition. So we propose two CUSUM control charts based on the likelihood ratio statistics for the preliminary analysis on the individual observations. One focuses on detecting the shifts in location in the historical data and the other is more general in detecting a shift in either the location and the scale or both.Moreover, the simulated results show that the proposed two control charts are, respectively, superior to their competitors not only in the detection of the sustained shifts but also in the detection of some other out-of-control situations considered in this paper.
CUSUM control charts based on likelihood ratio for preliminary analysis
2007-01-01
To detect and estimate a shift in either the mean and the deviation or both for the preliminary analysis, the statistical process control (SPC) tool, the control chart based on the likelihood ratio test (LRT), is the most popular method. Sullivan and woodall pointed out the test statistic lrt(n1, n2) is approximately distributed as x2(2) as the sample size n,n1 and n2 are very large, and the value of n1 = 2,3,..., n - 2 and that of n2 = n - n1. So it is inevitable that n1 or n2 is not large. In this paper the limit distribution of lrt(n1, n2) for fixed n1 or n2 is figured out, and the exactly analytic formulae for evaluating the expectation and the variance of the limit distribution are also obtained. In addition, the properties of the standardized likelihood ratio statistic slr(n1, n) are discussed in this paper. Although slr(n1, n) contains the most important information, slr(i, n)(i≠n1) also contains lots of information. The cumulative sum (CUSUM) control chart can obtain more information in this condition. So we propose two CUSUM control charts based on the likelihood ratio statistics for the preliminary analysis on the individual observations. One focuses on detecting the shifts in location in the historical data and the other is more general in detecting a shift in either the location and the scale or both. Moreover, the simulated results show that the proposed two control charts are, respectively, superior to their competitors not only in the detection of the sustained shifts but also in the detection of some other out-of-control situations considered in this paper.
[A New HAC Unsupervised Classifier Based on Spectral Harmonic Analysis].
Yang, Ke-ming; Wei, Hua-feng; Shi, Gang-qiang; Sun, Yang-yang; Liu, Fei
2015-07-01
Hyperspectral images classification is one of the important methods to identify image information, which has great significance for feature identification, dynamic monitoring and thematic information extraction, etc. Unsupervised classification without prior knowledge is widely used in hyperspectral image classification. This article proposes a new hyperspectral images unsupervised classification algorithm based on harmonic analysis(HA), which is called the harmonic analysis classifer (HAC). First, the HAC algorithm counts the first harmonic component and draws the histogram, so it can determine the initial feature categories and the pixel of cluster centers according to the number and location of the peak. Then, the algorithm is to map the waveform information of pixels to be classified spectrum into the feature space made up of harmonic decomposition times, amplitude and phase, and the similar features can be gotten together in the feature space, these pixels will be classified according to the principle of minimum distance. Finally, the algorithm computes the Euclidean distance of these pixels between cluster center, and merges the initial classification by setting the distance threshold. so the HAC can achieve the purpose of hyperspectral images classification. The paper collects spectral curves of two feature categories, and obtains harmonic decomposition times, amplitude and phase after harmonic analysis, the distribution of HA components in the feature space verified the correctness of the HAC. While the HAC algorithm is applied to EO-1 satellite Hyperion hyperspectral image and obtains the results of classification. Comparing with the hyperspectral image classifying results of K-MEANS, ISODATA and HAC classifiers, the HAC, as a unsupervised classification method, is confirmed to have better application on hyperspectral image classification.
Sordillo, Laura A.; Pu, Yang; Sordillo, Peter P.; Budansky, Yury; Alfano, R. R.
2014-05-01
Spectral profiles of tissues from patients with breast carcinoma, malignant carcinoid and non-small cell lung carcinoma were acquired using native fluorescence spectroscopy. A novel spectroscopic ratiometer device (S3-LED) with selective excitation wavelengths at 280 nm and 335 nm was used to produce the emission spectra of the key biomolecules, tryptophan and NADH, in the tissue samples. In each of the samples, analysis of emission intensity peaks from biomolecules showed increased 340 nm/440 nm and 340 nm/460 nm ratios in the malignant samples compared to their paired normal samples. This most likely represented increased tryptophan to NADH ratios in the malignant tissue samples compared to their paired normal samples. Among the non-small cell lung carcinoma and breast carcinomas, it appeared that tumors of very large size or poor differentiation had an even greater increase in the 340 nm/440 nm and 340 nm/460 nm ratios. In the samples of malignant carcinoid, which is known to be a highly metabolically active tumor, a marked increase in these ratios was also seen.
Power Spectral Analysis of Heart Rate Variability of Driver Fatigue
JIAO Kun; LI Zeng-yong; CHEN Ming; WANG Cheng-tao
2005-01-01
This investigation was to evaluate the driving fatigue based on power spectral analysis of heart rate variability (HRV) under vertical vibration. Forty healthy male subjects (29.7±3.5 years) were randomly divided into two groups, Group A (28.8±4.3 years) and Group B (30.6±2.7 years). Group A (experiment group) was required to perform the simulated driving and Group B (control group) kept calm for 90min. The frequency domain indices of HRV such as low frequency (0.040.15 Hz, LF), high frequency (0.15-0.4Hz, HF), LF/HF together with the indices of hemodynamics such as blood pressure (BP) and heart rate (HR) of the subjects between both groups were calculated and analyzed after the simulated driving. There were significances of the former indices between both groups (P＜0.05). All the data collected after experiment of Group A was observed the remarkable linear correlation (P＜0.05) and parameters and errors of their linear regression equation were stated (α=0.05, P＜0.001) in this paper, respectively. The present study investigated that sympathetic activity of the subjects enhanced after the simulated driving while parasympathetic activities decreased. The sympathovagal balance was also improved. As autonomic function indictors of HRV reflected fatigue level, quantitative evaluation of driving mental fatigue from physiological reaction could be possible.
Studying soil properties using visible and near infrared spectral analysis
Moretti, S.; Garfagnoli, F.; Innocenti, L.; Chiarantini, L.
2009-04-01
This research is carried out inside the DIGISOIL Project, whose purposes are the integration and improvement of in situ and proximal measurement technologies, for the assessment of soil properties and soil degradation indicators, going form the sensing technologies to their integration and their application in digital soil mapping. The study area is located in the Virginio river basin, about 30 km south of Firenze, in the Chianti area, where soils with agricultural suitability have a high economic value connected to the production of internationally famous wines and olive oils. The most common soil threats, such as erosion and landslide, may determine huge economic losses, which must be considered in farming management practices. This basin has a length of about 23 km for a basin area of around 60,3 Km2. Geological formations outcropping in the area are Pliocene to Pleistocene marine and lacustrine sediments in beds with almost horizontal bedding. Vineyards, olive groves and annual crops are the main types of land use. A typical Mediterranean climate prevails with a dry summer followed by intense and sometimes prolonged rainfall in autumn, decreasing in winter. In this study, three types of VNIR and SWIR techniques, operating at different scales and in different environments (laboratory spectroscopy, portable field spectroscopy) are integrated to rapidly quantify various soil characteristics, in order to acquire data for assessing the risk of occurrence for typically agricultural practice-related soil threats (swelling, compaction, erosion, landslides, organic matter decline, ect.) and to collect ground data in order to build up a spectral library to be used in image analysis from air-borne and satellite sensors. Difficulties encountered in imaging spectroscopy, such as influence of measurements conditions, atmospheric attenuation, scene dependency and sampling representation are investigated and mathematical pre-treatments, using proper algorithms, are applied and
Spectral analysis of HIV seropositivity among migrant workers entering Kuwait
Mohammad Hameed GHH
2008-03-01
Full Text Available Abstract Background There is paucity of published data on human immunodeficiency virus (HIV seroprevalence among migrant workers entering Middle-East particularly Kuwait. We took advantage of the routine screening of migrants for HIV infection, upon arrival in Kuwait from the areas with high HIV prevalence, to 1 estimate the HIV seroprevalence among migrant workers entering Kuwait and to 2 ascertain if any significant time trend or changes had occurred in HIV seroprevalence among these migrants over the study period. Methods The monthly aggregates of daily number of migrant workers tested and number of HIV seropositive were used to generate the monthly series of proportions of HIV seropositive (per 100,000 migrants over a period of 120 months from January 1, 1997 to December 31, 2006. We carried out spectral analysis of these time series data on monthly proportions (per 100,000 of HIV seropositive migrants. Results Overall HIV seroprevalence (per 100,000 among the migrants was 21 (494/2328582 (95% CI: 19 -23, ranging from 11 (95% CI: 8 – 16 in 2003 to 31 (95% CI: 24 -41 in 1998. There was no discernable pattern in the year-specific proportions of HIV seropositive migrants up to 2003; in subsequent years there was a slight but consistent increase in the proportions of HIV seropositive migrants. However, the Mann-Kendall test showed non-significant (P = 0.741 trend in de-seasonalized data series of proportions of HIV seropositive migrants. The spectral density had a statistically significant (P = 0.03 peak located at a frequency (radians 2.4, which corresponds to a regular cycle of three-month duration in this study. Auto-correlation function did not show any significant seasonality (correlation coefficient at lag 12 = – 0.025, P = 0.575. Conclusion During the study period, overall a low HIV seroprevalence (0.021% was recorded. Towards the end of the study, a slight but non-significant upward trend in the proportions of HIV seropositive
Michalsky, J.; Harrison, L. [State Univ. of New York, Albany, NY (United States)
1996-04-01
Our goal in the Atmospheric Radiation Measurement (ARM) Program is the improvement of radiation models used in general circulation models (GCMs), especially in the shortwave, (1) by providing improved shortwave radiometric measurements for the testing of models and (2) by developing methods for retrieving climatologically sensitive parameters that serve as input to shortwave and longwave models. At the Atmospheric Sciences Research Center (ASRC) in Albany, New York, we are acquiring downwelling direct and diffuse spectral irradiance, at six wavelengths, plus downwelling broadband longwave, and upwelling and downwelling broadband shortwave irradiances that we combine with National Weather Service surface and upper air data from the Albany airport as a test data set for ARM modelers. We have also developed algorithms to improve shortwave measurements made at the Southern Great Plains (SGP) ARM site by standard thermopile instruments and by the multifilter rotating shadowband radiometer (MFRSR) based on these Albany data sets. Much time has been spent developing techniques to retrieve column aerosol, water vapor, and ozone from the direct beam spectral measurements of the MFRSR. Additionally, we have had success in calculating shortwave surface albedo and aerosol optical depth from the ratio of direct to diffuse spectral reflectance.
LI Ping; RONG Meng-tian; HUANG Lei; YU Dan
2006-01-01
This paper presented a scheme of two-hop cellular network with fixed relay nodes (FRN). Based on this scheme, co-channel interference and signal interference ratio(SIR) received by base station(BS) and FRN were analyzed. Both the theoretical analysis and simulation results show that the SIR can be improved significantly when relays are employed in the network. The higher spectral efficiency can be obtained due to the improved two-hop link quality through the use of adaptive modulation and coding (AMC). The antenna height of FRN and the cell radius of BS and that of FRN influence SIR received by BS and FRN and the system spectral efficiency greatly. The proper antenna height of FRN and cell radius of BS and that of FRN were also given to get the highest spectral efficiency.
Spectral mixture analysis of EELS spectrum-images
Dobigeon, Nicolas; Brun, Nathalie
2012-01-01
Recent advances in detectors and computer science have enabled the acquisition and the processing of multidimensional datasets, in particular in the field of spectral imaging. Benefiting from these new developments, Earth scientists try to recover the reflectance spectra of macroscopic materials (e.g., water, grass, mineral types...) present in an observed scene and to estimate their respective proportions in each mixed pixel of the acquired image. This task is usually referred to as spectral...
Spectral analysis methods for the robust measurement of the flexural rigidity of biopolymers.
Valdman, David; Atzberger, Paul J; Yu, Dezhi; Kuei, Steve; Valentine, Megan T
2012-03-07
The mechanical properties of biopolymers can be determined from a statistical analysis of the ensemble of shapes they exhibit when subjected to thermal forces. In practice, extracting information from fluorescence microscopy images can be challenging due to low signal/noise ratios and other artifacts. To address these issues, we develop a suite of tools for image processing and spectral data analysis that is based on a biopolymer contour representation expressed in a spectral basis of orthogonal polynomials. We determine biopolymer shape and stiffness using global fitting routines that optimize a utility function measuring the amount of fluorescence intensity overlapped by such contours. This approach allows for filtering of high-frequency noise and interpolation over sporadic gaps in fluorescence. We use benchmarking to demonstrate the validity of our methods, by analyzing an ensemble of simulated images generated using a simulated biopolymer with known stiffness and subjected to various types of image noise. We then use these methods to determine the persistence lengths of taxol-stabilized microtubules. We find that single microtubules are well described by the wormlike chain polymer model, and that ensembles of chemically identical microtubules show significant heterogeneity in bending stiffness, which cannot be attributed to sampling or fitting errors. We expect these approaches to be useful in the study of biopolymer mechanics and the effects of associated regulatory molecules.
Spectral Analysis Methods for the Robust Measurement of the Flexural Rigidity of Biopolymers
Valdman, David; Atzberger, Paul J.; Yu, Dezhi; Kuei, Steve; Valentine, Megan T.
2012-01-01
The mechanical properties of biopolymers can be determined from a statistical analysis of the ensemble of shapes they exhibit when subjected to thermal forces. In practice, extracting information from fluorescence microscopy images can be challenging due to low signal/noise ratios and other artifacts. To address these issues, we develop a suite of tools for image processing and spectral data analysis that is based on a biopolymer contour representation expressed in a spectral basis of orthogonal polynomials. We determine biopolymer shape and stiffness using global fitting routines that optimize a utility function measuring the amount of fluorescence intensity overlapped by such contours. This approach allows for filtering of high-frequency noise and interpolation over sporadic gaps in fluorescence. We use benchmarking to demonstrate the validity of our methods, by analyzing an ensemble of simulated images generated using a simulated biopolymer with known stiffness and subjected to various types of image noise. We then use these methods to determine the persistence lengths of taxol-stabilized microtubules. We find that single microtubules are well described by the wormlike chain polymer model, and that ensembles of chemically identical microtubules show significant heterogeneity in bending stiffness, which cannot be attributed to sampling or fitting errors. We expect these approaches to be useful in the study of biopolymer mechanics and the effects of associated regulatory molecules. PMID:22404937
Analysis of wheezes using wavelet higher order spectral features.
Taplidou, Styliani A; Hadjileontiadis, Leontios J
2010-07-01
Wheezes are musical breath sounds, which usually imply an existing pulmonary obstruction, such as asthma and chronic obstructive pulmonary disease (COPD). Although many studies have addressed the problem of wheeze detection, a limited number of scientific works has focused in the analysis of wheeze characteristics, and in particular, their time-varying nonlinear characteristics. In this study, an effort is made to reveal and statistically analyze the nonlinear characteristics of wheezes and their evolution over time, as they are reflected in the quadratic phase coupling of their harmonics. To this end, the continuous wavelet transform (CWT) is used in combination with third-order spectra to define the analysis domain, where the nonlinear interactions of the harmonics of wheezes and their time variations are revealed by incorporating instantaneous wavelet bispectrum and bicoherence, which provide with the instantaneous biamplitude and biphase curves. Based on this nonlinear information pool, a set of 23 features is proposed for the nonlinear analysis of wheezes. Two complementary perspectives, i.e., general and detailed, related to average performance and to localities, respectively, were used in the construction of the feature set, in order to embed trends and local behaviors, respectively, seen in the nonlinear interaction of the harmonic elements of wheezes over time. The proposed feature set was evaluated on a dataset of wheezes, acquired from adult patients with diagnosed asthma and COPD from a lung sound database. The statistical evaluation of the feature set revealed discrimination ability between the two pathologies for all data subgroupings. In particular, when the total breathing cycle was examined, all 23 features, but one, showed statistically significant difference between the COPD and asthma pathologies, whereas for the subgroupings of inspiratory and expiratory phases, 18 out of 23 and 22 out of 23 features exhibited discrimination power, respectively
EEG spectral analysis of attention in ADHD: implications for neurofeedback training?
Hartmut eHeinrich
2014-08-01
Full Text Available Objective: In children with attention-deficit/hyperactivity disorder (ADHD, an increased theta/beta ratio in the resting EEG typically serves as a rationale to conduct theta/beta neurofeedback training. However, this finding is increasingly challenged. As neurofeedback may rather target an active than a passive state, we studied the EEG in a condition that requires attention.Methods: In children with ADHD of the DSM-IV combined type (ADHD-C; N=15 and of the predominantly inattentive type (ADHD-I; N=9 and in typically developing children (N=19, EEG spectral analysis was conducted for segments during the attention network test without processing of stimuli and overt behavior. Frontal (F3, Fz, F4, central (C3, Cz, C4 and parietal (P3, Pz, P4 electrodes were included in the statistical analysis. To investigate if EEG spectral parameters are related to performance measures, correlation coefficients were calculated.Results: Particularly in the ADHD-C group, higher theta and alpha activity was found with the most prominent effect in the upper-theta/lower-alpha (5.5-10.5 Hz range. In the ADHD-I group, a significantly higher theta/beta ratio was observed at single electrodes (F3, Fz and a tendency for a higher theta/beta ratio when considering all electrodes (large effect size. Higher 5.5-10.5 Hz activity was associated with higher reaction time variability with the effect most prominent in the ADHD-C group. A higher theta/beta ratio was associated with higher reaction times, particularly in the ADHD-I group.Conclusions: 1. In an attention demanding period, children with ADHD are characterized by an underactivated state in the EEG with subtype-specific differences. 2. The functional relevance of related EEG parameters is indicated by associations with performance (reaction time measures. 3. Findings provide a rationale for applying NF protocols targeting theta (and alpha activity and the theta/beta ratio in subgroups of children with ADHD.
Synthesis, spectral, computational and thermal analysis studies of metallocefotaxime antibiotics.
Masoud, Mamdouh S; Ali, Alaa E; Elasala, Gehan S
2015-01-01
Cefotaxime metal complexes of Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Hg(II) and two mixed metals complexes of (Fe,Cu) and (Fe,Ni) were synthesized and characterized by elemental analysis, IR, electronic spectra, magnetic susceptibility and ESR spectra. The studies proved that cefotaxime may act as mono, bi, tri and tetra-dentate ligand through oxygen atoms of lactam carbonyl, carboxylic or amide carbonyl groups and nitrogen atom of thiazole ring. From the magnetic measurements and electronic spectral data, octahedral structures were proposed for all complexes. Quantum chemical methods have been performed for cefotaxime to calculate charges, bond lengths, bond angles, dihedral angles, electronegativity (χ), chemical potential (μ), global hardness (η), softness (σ) and the electrophilicity index (ω). The thermal decomposition of the prepared metals complexes was studied by TGA, DTA and DSC techniques. Thermogravimetric studies revealed the presence of lattice or coordinated water molecules in all the prepared complexes. The decomposition mechanisms were suggested. The thermal decomposition of the complexes ended with the formation of metal oxides and carbon residue as a final product except in case of Hg complex, sublimation occur at the temperature range 376.5-575.0 °C so, only carbon residue was produced during thermal decomposition. The orders of chemical reactions (n) were calculated via the peak symmetry method and the activation parameters were computed from the thermal decomposition data. The geometries of complexes may be converted from Oh to Td during the thermal decomposition steps.
The spectral analysis of photoplethysmography to evaluate an independent cardiovascular risk factor
Gandhi PG
2014-12-01
Full Text Available Pratiksha G Gandhi,1 Gundu HR Rao2 1IPC Heart Care Centre, Mumbai, India; 2University of Minnesota, Minneapolis, MN, USABackground: In this study, we evaluate homeostatic markers correlated to autonomic nervous and endothelial functions in a population of coronary artery disease (CAD patients versus a control group. Since CAD is the highest risk marker for sudden cardiac death, the study objective is to determine whether an independent cardiovascular risk score based on these markers can be used alongside known conventional cardiovascular risk markers to strengthen the understanding of a patient's vascular state.Materials and methods: Sixty-five subjects (13 women with a mean age of 62.9 years (range 40–80 years who were diagnosed with CAD using coronary angiography (group 1 and seventy-two subjects (29 women with a mean age of 45.1 years (range 18–85 years who claimed they were healthy (group 2 were included in the study. These subjects underwent examination with the TM-Oxi and SudoPath systems at IPC Heart Care Centers in Mumbai, India. The TM-Oxi system takes measurements from a blood pressure device and a pulse oximeter. The SudoPath measures galvanic skin response to assess the sudomotor pathway function. Spectral analysis of the photoplethysmograph (PTG waveform and electrochemical galvanic skin response allow the TM-Oxi and SudoPath systems to calculate several homeostatic markers, such as the PTG index (PTGi, PTG very low frequency index (PTGVLFi, and PTG ratio (PTGr. The focus of this study was to evaluate these markers (PTGi, PTGVLFi, and PTGr in CAD patients against a control group, and to calculate an independent cardiovascular risk factor score: the PTG cardiovascular disease risk score (PTG CVD, calculated solely from these markers. We compared PTGi, PTGVLFi, PTGr, and PTG CVD scores between the CAD patient group and the healthy control group. Statistical analyses were performed using receiver operating characteristic curves to
Spectral image analysis of mutual illumination between florescent objects.
Tominaga, Shoji; Kato, Keiji; Hirai, Keita; Horiuchi, Takahiko
2016-08-01
This paper proposes a method for modeling and component estimation of the spectral images of the mutual illumination phenomenon between two fluorescent objects. First, we briefly describe the bispectral characteristics of a single fluorescent object, which are summarized as a Donaldson matrix. We suppose that two fluorescent objects with different bispectral characteristics are located close together under a uniform illumination. Second, we model the mutual illumination between two objects. It is shown that the spectral composition of the mutual illumination is summarized with four components: (1) diffuse reflection, (2) diffuse-diffuse interreflection, (3) fluorescent self-luminescence, and (4) interreflection by mutual fluorescent illumination. Third, we develop algorithms for estimating the spectral image components from the observed images influenced by the mutual illumination. When the exact Donaldson matrices caused by the mutual illumination influence are unknown, we have to solve a non-linear estimation problem to estimate both the spectral functions and the location weights. An iterative algorithm is then proposed to solve the problem based on the alternate estimation of the spectral functions and the location weights. In our experiments, the feasibility of the proposed method is shown in three cases: the known Donaldson matrices, weak interreflection, and strong interreflection.
Cui, Qian; Shi, Jiancheng; Xu, Yuanliu
2011-12-01
Water is the basic needs for human society, and the determining factor of stability of ecosystem as well. There are lots of lakes on Tibet Plateau, which will lead to flood and mudslide when the water expands sharply. At present, water area is extracted from TM or SPOT data for their high spatial resolution; however, their temporal resolution is insufficient. MODIS data have high temporal resolution and broad coverage. So it is valuable resource for detecting the change of water area. Because of its low spatial resolution, mixed-pixels are common. In this paper, four spectral libraries are built using MOD09A1 product, based on that, water body is extracted in sub-pixels utilizing Multiple Endmembers Spectral Mixture Analysis (MESMA) using MODIS daily reflectance data MOD09GA. The unmixed result is comparing with contemporaneous TM data and it is proved that this method has high accuracy.
Odds ratio analysis in women with endometrial cancer
Katarzyna Plagens-Rotman
2016-03-01
Full Text Available Introduction : Despite the progress in diagnosis and treatment of malignant tumours, the effects of treatment are insufficient. Reduction of the risk of cervical, ovarian, and endometrial cancer is possible by introducing preventative actions. Aim of the study: The aim of the thesis is the analysis of selected risk factors that may affect the increase or decrease in the odds ratio of developing endometrial cancer. Material and methods: The study was conducted among patients of the Gynaecology and Obstetrics Hospital of Poznań University of Medical Sciences in the years 2011-2013. The research included a total of 548 female respondents aged between 40 and 84 years. Women responded to questions assessing elements of lifestyle such as consumption of alcohol, smoking, and eating certain groups of foods. Results: The respondents consuming fruits and vegetables several times a week have a reduced risk of odds ratio and the OR is 0.85; 95% CI: 0.18-4.09, compared to the women who rarely consume vegetables and fruits. Consumption of whole-wheat bread several times a week reduces the risk of developing the cancer, OR = 0.59; 95% CI: 0.14-2.47, compared to women not consuming wholegrain bread at all. Respondents who consumed red meat, such as veal, pork, and lamb in the amount of 101-200 g per day have an increased risk of developing the disease: OR = 2.16; 95% CI: 1.09-4.28, compared to women not consuming red meat at all. Conclusions : A diet rich in fruit and vegetables, onions, garlic, whole grains, and beans should be introduced in order to reduce the risk of endometrial cancer. The consumption of red meat and white pasta should be reduced or even eliminated.
Rotating shadowband radiometer development and analysis of spectral shortwave data
Michalsky, J.; Harrison, L.; Min, Q. [State Univ. of New York, Albany, NY (United States)] [and others
1996-04-01
Our goals in the Atmospheric Radiation Measurement (ARM) Program are improved measurements of spectral shortwave radiation and improved techniques for the retrieval of climatologically sensitive parameters. The multifilter rotating shadowband radiometer (MFRSR) that was developed during the first years of the ARM program has become a workhorse at the Southern Great Plains (SGP) Cloud and Radiation Testbed (CART) site, and it is widely deployed in other climate programs. We have spent most of our effort this year developing techniques to retrieve column aerosol, water vapor, and ozone from direct beam spectral measurements of the MFRSR. Additionally, we have had some success in calculating shortwave surface diffuse spectral irradiance. Using the surface albedo and the global irradiance, we have calculated cloud optical depths. From cloud optical depth and liquid water measured with the microwave radiometer, we have calculated effective liquid cloud particle radii. The rest of the text will provide some detail regarding each of these efforts.
Perturbative Analysis of Spectral Singularities and Their Optical Realizations
Mostafazadeh, Ali
2012-01-01
We develop a perturbative method of computing spectral singularities of a Schreodinger operator defined by a general complex potential that vanishes outside a closed interval. These can be realized as zero-width resonances in optical gain media and correspond to a lasing effect that occurs at the threshold gain. Their time-reversed copies yield coherent perfect absorption of light that is also known as an antilaser. We use our general results to establish the exactness of the n-th order perturbation theory for an arbitrary complex potential consisting of n delta-functions, obtain an exact expression for the transfer matrix of these potentials, and examine spectral singularities of complex barrier potentials of arbitrary shape. In the context of optical spectral singularities, these correspond to inhomogeneous gain media.
Inverse spectral analysis for singular differential operators with matrix coefficients
Nour el Houda Mahmoud
2006-02-01
Full Text Available Let $L_alpha$ be the Bessel operator with matrix coefficients defined on $(0,infty$ by $$ L_alpha U(t = U''(t+ {I/4-alpha^2over t^2}U(t, $$ where $alpha$ is a fixed diagonal matrix. The aim of this study, is to determine, on the positive half axis, a singular second-order differential operator of $L_alpha+Q$ kind and its various properties from only its spectral characteristics. Here $Q$ is a matrix-valued function. Under suitable circumstances, the solution is constructed by means of the spectral function, with the help of the Gelfund-Levitan process. The hypothesis on the spectral function are inspired on the results of some direct problems. Also the resolution of Fredholm's equations and properties of Fourier-Bessel transforms are used here.
Spectral analysis of the turbulent mixing of two fluids
Steinkamp, M.J.
1996-02-01
The authors describe a spectral approach to the investigation of fluid instability, generalized turbulence, and the interpenetration of fluids across an interface. The technique also applies to a single fluid with large variations in density. Departures of fluctuating velocity components from the local mean are far subsonic, but the mean Mach number can be large. Validity of the description is demonstrated by comparisons with experiments on turbulent mixing due to the late stages of Rayleigh-Taylor instability, when the dynamics become approximately self-similar in response to a constant body force. Generic forms for anisotropic spectral structure are described and used as a basis for deriving spectrally integrated moment equations that can be incorporated into computer codes for scientific and engineering analyses.
Systematic Spectral Lag Analysis of Swift Known-z GRBs
Yuta Kawakubo
2015-01-01
arrive earlier than soft photons. The lag-luminosity relation is the empirical relationship between the isotropic peak luminosity and the spectral lag. We calculated the spectral lags for 40 known redshift GRBs observed by Swift addition to the previous 31 GRB samples. We confirmed that most of our samples follow the lag-luminosity relation. However, we noticed that there are some GRBs which show a significant scatter from the relation. We also confirm that the relationship between the break time and the luminosity of the X-ray afterglow (so-called Dainotti relation extends up to the lag-luminosity relation.
Croff, K. L.; Sigurdsson, H.; Carey, S.; Alexandri, M.; Sakellariou, D.; Nomikou, P.
2006-12-01
Multibeam bathymetry mapping and seismic airgun surveys of the submarine region around the Santorini volcanic field in the Hellenic Arc (Greece) have revealed regions of terraced or step-like topography. These features may be related to the transport and deposition of submarine pyroclastic flows from the last major eruption of this volcano (~3600yrs. B.P.). The uppermost sediment sequence identified in seismic records has an average thickness of approximately 29 meters and may represent the pyroclastic flow deposits from this eruption. These terraced or step-like features are mainly located in areas that are approximately five kilometers offshore and at depths in the range of 200 to 800 meters. The seafloor in these areas has slope ratios on the order of 1:20. Profiles of the seafloor topography were sampled from seismic profiles that radiate from the Sanotrini caldera in five regions of interest. Spectral analysis of seafloor topography has been carried out to determine spectral characteristics of these features, including power spectrum, periodicity and amplitude of the waveforms, variance, and roughness of topography. The results are compared to surface features of the subaqueous pyroclastic deposits from the 1883 explosive eruption of Krakatau (Indonesia) and other areas with similar environments, to determine the parameters that are characteristic of this new feature of submarine volcaniclastic deposits.
Least Squares Spectral Analysis and Its Application to Superconducting Gravimeter Data Analysis
YIN Hui; Spiros D. Pagiatakis
2004-01-01
Detection of a periodic signal hidden in noise is the goal of Superconducting Gravimeter (SG) data analysis. Due to spikes, gaps, datum shrifts (offsets) and other disturbances, the traditional FFT method shows inherent limitations. Instead, the least squares spectral analysis (LSSA) has showed itself more suitable than Fourier analysis of gappy, unequally spaced and unequally weighted data series in a variety of applications in geodesy and geophysics. This paper reviews the principle of LSSA and gives a possible strategy for the analysis of time series obtained from the Canadian Superconducting Gravimeter Installation (CGSI), with gaps, offsets, unequal sampling decimation of the data and unequally weighted data points.
Staab, Wieland; Hottowitz, Ralf; Sohns, Christian; Sohns, Jan Martin; Gilbert, Fabian; Menke, Jan; Niklas, Andree; Lotz, Joachim
2014-07-01
[Purpose] A wide variety of accelerometer tools are used to estimate human movement, but there are no adequate data relating to gait symmetry parameters in the context of knee osteoarthritis. This study's purpose was to evaluate a 3D-kinematic system using body-mounted sensors (gyroscopes and accelerometers) on the trunk and limbs. This is the first study to use spectral analysis for data post processing. [Subjects] Twelve patients with unilateral knee osteoarthritis (OA) (10 male) and seven age-matched controls (6 male) were studied. [Methods] Measurements with 3-D accelerometers and gyroscopes were compared to video analysis with marker positions tracked by a six-camera optoelectronic system (VICON 460, Oxford Metrics). Data were recorded using the 3D-kinematic system. [Results] The results of both gait analysis systems were significantly correlated. Five parameters were significantly different between the knee OA and control groups. To overcome time spent in expensive post-processing routines, spectral analysis was performed for fast differentiation between normal gait and pathological gait signals using the 3D-kinematic system. [Conclusions] The 3D-kinematic system is objective, inexpensive, accurate and portable, and allows long-term recordings in clinical, sport as well as ergonomic or functional capacity evaluation (FCE) settings. For fast post-processing, spectral analysis of the recorded data is recommended.
[The linearity analysis of ultrahigh temperature FTIR spectral emissivity measurement system].
Wang, Zong-wei; Dai, Jing-min; He, Xiao-wa; Yang, Chun-ling
2012-02-01
To study thermal radiation properties of special materials at high temperature in aerospace fields, the ultrahigh temperature spectral emissivity measurement system with Fourier spectrometer has been established. The linearity of system is the guarantee of emissivity measurement precision. Through measuring spectral radiation signals of a blackbody source at different temperatures, the function relations between spectral signal values and blackbody spectral radiation luminance of every spectrum points were calculated with the method of multi-temperature and multi-spectrum linear fitting. The spectral radiation signals of blackbody were measured between 1 000 degrees C and 2 000 degrees C in the spectral region from 3 to 20 microm. The linear relations between spectral signal and theory line at wavelength of 4 microm were calculated and introduced. The spectral response is well good between 4 and 18 microm, the spectral linearity are less than 1% except CO2 strong absorption spectrum regions. The results show that when the errors of measured spectrum radiation and linear fitting theory lines are certain, the higher the temperature, the smaller the spectral errors on emissivity. The linearity analysis of spectrum response is good at eliminating errors caused by individual temperature' disturbance to the spectra.
Spectral and Temporal Laser Fluorescence Analysis Such as for Natural Aquatic Environments
Chekalyuk, Alexander (Inventor)
2015-01-01
An Advanced Laser Fluorometer (ALF) can combine spectrally and temporally resolved measurements of laser-stimulated emission (LSE) for characterization of dissolved and particulate matter, including fluorescence constituents, in liquids. Spectral deconvolution (SDC) analysis of LSE spectral measurements can accurately retrieve information about individual fluorescent bands, such as can be attributed to chlorophyll-a (Chl-a), phycobiliprotein (PBP) pigments, or chromophoric dissolved organic matter (CDOM), among others. Improved physiological assessments of photosynthesizing organisms can use SDC analysis and temporal LSE measurements to assess variable fluorescence corrected for SDC-retrieved background fluorescence. Fluorescence assessments of Chl-a concentration based on LSE spectral measurements can be improved using photo-physiological information from temporal measurements. Quantitative assessments of PBP pigments, CDOM, and other fluorescent constituents, as well as basic structural characterizations of photosynthesizing populations, can be performed using SDC analysis of LSE spectral measurements.
Fereidouni, Farzad; Bader, Arjen N; Colonna, Anne; Gerritsen, Hans C
2014-08-01
Skin contains many autofluorescent components that can be studied using spectral imaging. We employed a spectral phasor method to analyse two photon excited autofluorescence and second harmonic generation images of in vivo human skin. This method allows segmentation of images based on spectral features. Various structures in the skin could be distinguished, including Stratum Corneum, epidermal cells and dermis. The spectral phasor analysis allowed investigation of their fluorescence composition and identification of signals from NADH, keratin, FAD, melanin, collagen and elastin. Interestingly, two populations of epidermal cells could be distinguished with different melanin content.
Methodology for diagnosing of skin cancer on images of dermatologic spots by spectral analysis.
Guerra-Rosas, Esperanza; Álvarez-Borrego, Josué
2015-10-01
In this paper a new methodology for the diagnosing of skin cancer on images of dermatologic spots using image processing is presented. Currently skin cancer is one of the most frequent diseases in humans. This methodology is based on Fourier spectral analysis by using filters such as the classic, inverse and k-law nonlinear. The sample images were obtained by a medical specialist and a new spectral technique is developed to obtain a quantitative measurement of the complex pattern found in cancerous skin spots. Finally a spectral index is calculated to obtain a range of spectral indices defined for skin cancer. Our results show a confidence level of 95.4%.
Subiakto Soekarno
2012-01-01
Full Text Available Insurance industry stands as a service business that plays a significant role in Indonesiaeconomical condition. The development of insurance industry in Indonesia, both of generalinsurance and life insurance, has increased very fast. The general insurance industry itselfdivided into two major players which are local private company and Joint Venture Company.Lately, the use of statistical techniques and financial ratios models to asses financial institutionsuch as insurance company have been used as one of the appropriate combination inpredicting the performance of an industry. This research aims to distinguish between JointVenture General Insurance Companies that have a good performance and those who are lessperforming well using Discriminant Analysis. Further, the findings led that DiscriminantAnalysis is able to distinguish Joint Venture General Insurance Companies that have a goodperformance and those who are not performing well. There are also six ratios which are RBC,Technical Reserve to Investment Ratio, Debt Ratio, Return on Equity, Loss Ratio, and ExpenseRatio that stand as the most influential ratios to distinguish the performance of joint venturegeneral insurance companies. In addition, the result suggest business people to be concernedtoward those six ratios, to increase their companies’ performance.Key words: general insurance, financial ratio, discriminant analysis
Subiakto Soekarno
2012-01-01
Full Text Available Insurance industry stands as a service business that plays a significant role in Indonesiaeconomical condition. The development of insurance industry in Indonesia, both of generalinsurance and life insurance, has increased very fast. The general insurance industry itselfdivided into two major players which are local private company and Joint Venture Company.Lately, the use of statistical techniques and financial ratios models to asses financial institutionsuch as insurance company have been used as one of the appropriate combination inpredicting the performance of an industry. This research aims to distinguish between JointVenture General Insurance Companies that have a good performance and those who are lessperforming well using Discriminant Analysis. Further, the findings led that DiscriminantAnalysis is able to distinguish Joint Venture General Insurance Companies that have a goodperformance and those who are not performing well. There are also six ratios which are RBC,Technical Reserve to Investment Ratio, Debt Ratio, Return on Equity, Loss Ratio, and ExpenseRatio that stand as the most influential ratios to distinguish the performance of joint venturegeneral insurance companies. In addition, the result suggest business people to be concernedtoward those six ratios, to increase their companies’ performance.Key words: general insurance, financial ratio, discriminant analysis
Test and analysis of spectral response for UV image intensifier
Qian, Yunsheng; Liu, Jian; Feng, Cheng; Lv, Yang; Zhang, Yijun
2015-10-01
The UV image intensifier is one kind of electric vacuum imaging device based on principle of photoelectronic imaging. To achieve solar-blind detection, its spectral response characteristic is extremely desirable. A broad spectrum response measurement system is developed. This instrument uses EQ-99 laser-driven light source to get broad spectrum in the range of 200 nm to 1700 nm. A special preamplifier as well as a test software is work out. The spectral response of the image intensifier can be tested in the range of 200~1700 nm. Using this spectrum response measuring instrument, the UV image intensifiers are tested. The spectral response at the spectral range of 200 nm to 600 nm are obtained. Because of the quantum efficiency of Te-Cs photocathode used in image intens ifier above 280nm wavelength still exists, especially at 280 nm to 320nm.Therefore, high-performance UV filters is required for solar blind UV detection. Based on two sets of UV filters, the influence of solar radiation on solar blind detection is calculated and analyzed.
Two-body threshold spectral analysis, the critical case
Skibsted, Erik; Wang, Xue Ping
We study in dimension $d\\geq2$ low-energy spectral and scattering asymptotics for two-body $d$-dimensional Schrödinger operators with a radially symmetric potential falling off like $-\\gamma r^{-2},\\;\\gamma>0$. We consider angular momentum sectors, labelled by $l=0,1,\\dots$, for which $\\gamma...
Prostate cancer spectral multifeature analysis using TRUS images.
Mohamed, S S; Salama, M A
2008-04-01
This paper focuses on extracting and analyzing different spectral features from transrectal ultrasound (TRUS) images for prostate cancer recognition. First, the information about the images' frequency domain features and spatial domain features are combined using a Gabor filter and then integrated with the expert radiologist's information to identify the highly suspicious regions of interest (ROIs). The next stage of the proposed algorithm is to scan each identified region in order to generate the corresponding 1-D signal that represents each region. For each ROI, possible spectral feature sets are constructed using different new geometrical features extracted from the power spectrum density (PSD) of each region's signal. Next, a classifier-based algorithm for feature selection using particle swarm optimization (PSO) is adopted and used to select the optimal feature subset from the constructed feature sets. A new spectral feature set for the TRUS images using estimation of signal parameters via rotational invariance technique (ESPRIT) is also constructed, and its ability to represent tissue texture is compared to the PSD-based spectral feature sets using the support vector machines (SVMs) classifier. The accuracy obtained ranges from 72.2% to 94.4%, with the best accuracy achieved by the ESPRIT feature set.
Time-resolved spectral analysis of Radachlorin luminescence in water
Belik, V. P.; Gadzhiev, I. M.; Semenova, I. V.; Vasyutinskii, O. S.
2017-05-01
We report results of spectral- and time-resolved study of Radachlorin photosensitizer luminescence in water in the spectral range of 950-1350nm and for determination of the photosensitizer triplet state and the singlet oxygen lifetimes responsible for singlet oxygen generation and degradation. At any wavelength within the explored spectral range the luminescence decay contained two major contributions: a fast decay at the ns time scale and a slow evolution at the μs time scale. The fast decay was attributed to electric dipole fluorescence transitions in photosensitizer molecules and the slow evolution to intercombination phosphorescence transitions in singlet oxygen and photosensitizer molecules. Relatively high-amplitude ns peak observed at all wavelengths suggests that singlet oxygen monitoring with spectral isolation methods alone, without additional temporal resolution can be controversial. In the applied experimental conditions the total phosphorescence signal at any wavelength contained a contribution from the photosensitizer triplet state decay, while at 1274nm the singlet oxygen phosphorescence dominated. The results obtained can be used for optimization of the methods of singlet oxygen monitoring and imaging.
Detecting gallbladders in chicken livers using spectral analysis
Jørgensen, Anders; Mølvig Jensen, Eigil; Moeslund, Thomas B.
2015-01-01
This paper presents a method for detecting gallbladders attached to chicken livers using spectral imaging. Gallbladders can contaminate good livers, making them unfit for human consumption. A data set consisting of chicken livers with and without gallbladders, has been captured using 33 wavelengt...
Detecting gallbladders in chicken livers using spectral analysis
Jørgensen, Anders; Mølvig Jensen, Eigil; Moeslund, Thomas B.
2015-01-01
This paper presents a method for detecting gallbladders attached to chicken livers using spectral imaging. Gallbladders can contaminate good livers, making them unfit for human consumption. A data set consisting of chicken livers with and without gallbladders, has been captured using 33 wavelengths...
Ultra-wideband spectral analysis using S2 technology
Krishna Mohan, R. [Spectrum Lab, Montana State University, Bozeman, MT 59717 (United States)]. E-mail: krishna@spectrum.montana.edu; Chang, T. [Spectrum Lab, Montana State University, Bozeman, MT 59717 (United States); Tian, M. [Spectrum Lab, Montana State University, Bozeman, MT 59717 (United States); Department of Physics, Montana State University, Bozeman, MT 59717 (United States); Bekker, S. [Spectrum Lab, Montana State University, Bozeman, MT 59717 (United States); Olson, A. [Spectrum Lab, Montana State University, Bozeman, MT 59717 (United States); Ostrander, C. [Spectrum Lab, Montana State University, Bozeman, MT 59717 (United States); Khallaayoun, A. [Spectrum Lab, Montana State University, Bozeman, MT 59717 (United States); Dollinger, C. [Spectrum Lab, Montana State University, Bozeman, MT 59717 (United States); Babbitt, W.R. [Spectrum Lab, Montana State University, Bozeman, MT 59717 (United States); Department of Physics, Montana State University, Bozeman, MT 59717 (United States); Cole, Z. [Spectrum Lab, Montana State University, Bozeman, MT 59717 (United States); S2 Corporation, Bozeman, MT 59718 (United States); Reibel, R.R. [Spectrum Lab, Montana State University, Bozeman, MT 59717 (United States); S2 Corporation, Bozeman, MT 59718 (United States); Merkel, K.D. [Spectrum Lab, Montana State University, Bozeman, MT 59717 (United States); S2 Corporation, Bozeman, MT 59718 (United States); Sun, Y. [Department of Physics, Montana State University, Bozeman, MT 59717 (United States); Cone, R. [Department of Physics, Montana State University, Bozeman, MT 59717 (United States); Schlottau, F. [University of Colorado, Boulder, CO 80309 (United States); Wagner, K.H. [University of Colorado, Boulder, CO 80309 (United States)
2007-11-15
This paper outlines the efforts to develop an ultra-wideband spectrum analyzer that takes advantage of the broad spectral response and fine spectral resolution ({approx}25 kHz) of spatial-spectral (S2) materials. The S2 material can process the full spectrum of broadband microwave transmissions, with adjustable time apertures (down to 100 {mu}s) and fast update rates (up to 1 kHz). A cryogenically cooled Tm:YAG crystal that operates on microwave signals modulated onto a stabilized optical carrier at 793 nm is used as the core for the spectrum analyzer. Efforts to develop novel component technologies that enhance the performance of the system and meet the application requirements are discussed, including an end-to-end device model for parameter optimization. We discuss the characterization of new ultra-wide bandwidth S2 materials. Detection and post-processing module development including the implementation of a novel spectral recovery algorithm using field programmable gate array technology (FPGA) is also discussed.
Statistical Analysis of Spectral Properties and Prosodic Parameters of Emotional Speech
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.
Practical Aspects of the Spectral Analysis of Irregularly Sampled Data With Time-Series Models
Broersen, P.M.T.
2009-01-01
Several algorithms for the spectral analysis of irregularly sampled random processes can estimate the spectral density for a low frequency range. A new time-series method extended that frequency range with a factor of thousand or more. The new algorithm has two requirements to give useful results. F
王倩; 杨忠东; 毕研盟
2014-01-01
detector such as spectral resolution,sampling ratio and sign-to-noise ratio (SNR)on CO2 detection are analyzed. Typical characteristics of hyper spectral CO2 detector on TANSAT are grating spectrometer and array-based detector.To achieve the column averaged atmospheric CO2 dry air mole fraction (X CO 2 )precision re-quirements of 1×10 -6 -4×10 -6 ,hyper spectral CO2 detector should provide high resolution at first to re-solve CO2 absorption lines from continuous spectra of reflected sunlight.Compared to a variety of simula-ted spectral resolutions,the spectral resolution of hyper spectral CO2 detector on TANSAT can resolve CO2 spectral features and maintain the moderate radiance sensitivity.Since small size array detector-based instruments may suffer from undersampling of the spectra,influences of spectral undersampling to CO2 ab-sorption spectra are studied,indicating that sampling ratio should exceed 2 pixels/FWHM to ensure the accuracy of CO2 spectrum. SNR is one of the most important parameters of hyper spectral CO2 detectors to ensure the reliability. SNR requirements of CO2 detector to different detection precisions are explored based on the radiance sen-sitivity factors.Results show that it is difficult to achieve SNR to detect 1×10 -6 -4×10 -6 CO2 concentra-tion change in the boundary layer by solar shortwave infrared passive remote sensing,limited by the in-strument development condition and level at present.However,the instrument SNR to detect 1% change in the CO2 column concentration is attainable.These results are not only conductive to universal applica-tions and guides on developing grating spectrometer,but also helpful to better understand the complexity of CO2 retrieval.
Non-stationary (13)C-metabolic flux ratio analysis.
Hörl, Manuel; Schnidder, Julian; Sauer, Uwe; Zamboni, Nicola
2013-12-01
(13)C-metabolic flux analysis ((13)C-MFA) has become a key method for metabolic engineering and systems biology. In the most common methodology, fluxes are calculated by global isotopomer balancing and iterative fitting to stationary (13)C-labeling data. This approach requires a closed carbon balance, long-lasting metabolic steady state, and the detection of (13)C-patterns in a large number of metabolites. These restrictions mostly reduced the application of (13)C-MFA to the central carbon metabolism of well-studied model organisms grown in minimal media with a single carbon source. Here we introduce non-stationary (13)C-metabolic flux ratio analysis as a novel method for (13)C-MFA to allow estimating local, relative fluxes from ultra-short (13)C-labeling experiments and without the need for global isotopomer balancing. The approach relies on the acquisition of non-stationary (13)C-labeling data exclusively for metabolites in the proximity of a node of converging fluxes and a local parameter estimation with a system of ordinary differential equations. We developed a generalized workflow that takes into account reaction types and the availability of mass spectrometric data on molecular ions or fragments for data processing, modeling, parameter and error estimation. We demonstrated the approach by analyzing three key nodes of converging fluxes in central metabolism of Bacillus subtilis. We obtained flux estimates that are in agreement with published results obtained from steady state experiments, but reduced the duration of the necessary (13)C-labeling experiment to less than a minute. These results show that our strategy enables to formally estimate relative pathway fluxes on extremely short time scale, neglecting cellular carbon balancing. Hence this approach paves the road to targeted (13)C-MFA in dynamic systems with multiple carbon sources and towards rich media.
Spectral compression algorithms for the analysis of very large multivariate images
Keenan, Michael R.
2007-10-16
A method for spectrally compressing data sets enables the efficient analysis of very large multivariate images. The spectral compression algorithm uses a factored representation of the data that can be obtained from Principal Components Analysis or other factorization technique. Furthermore, a block algorithm can be used for performing common operations more efficiently. An image analysis can be performed on the factored representation of the data, using only the most significant factors. The spectral compression algorithm can be combined with a spatial compression algorithm to provide further computational efficiencies.
Spectral analysis of heart rate dynamics in elderly persons with postprandial hypotension
Ryan, S. M.; Goldberger, A. L.; Ruthazer, R.; Mietus, J.; Lipsitz, L. A.
1992-01-01
Prior studies suggest that postprandial hypotension in elderly persons may be due to defective sympathetic nervous system activation. We examined autonomic control of heart rate (HR) after a meal using spectral analysis of HR data in 13 old (89 +/- 6 years) and 7 young (24 +/- 4 years) subjects. Total spectral power, an index of overall HR variability, was calculated for the frequency band between 0.01 and 0.40 Hz. Relatively low-frequency power, associated with sympathetic nervous system and baroreflex activation, was calculated for the 0.01 to 0.15 Hz band. High-frequency power, representing parasympathetic influences on HR, was calculated for the 0.15 to 0.40 Hz band. Mean arterial blood pressure declined 27 +/- 8 mm Hg by 60 minutes after the meal in elderly subjects, compared with 9 +/- 8 mm Hg in young subjects (p less than or equal to 0.0001, young vs old). The mean change in low-frequency HR power from 30 to 50 minutes after the meal was +19.4 +/- 25.3 U in young subjects versus -0.1 +/- 1.5 U in old subjects (p less than or equal to 0.02). Mean change in total power was also greater in young (19.0 +/- 26.6 U) subjects compared with old subjects (0.0 +/- 1.6 U, p greater than or equal to 0.02). Mean ratio of low:high-frequency power increased 3.1 +/- 3.3 U in young subjects vs 0.5 +/- 2.7 U in old subjects (p less than or equal to 0.01). The increase in low-frequency HR power and in the low:high frequency band ratio in young subjects is consistent with sympathetic activation in the postprandial period.(ABSTRACT TRUNCATED AT 250 WORDS).
Atomistic interpretation of solid solution hardening from spectral analysis.
Plendl, J N
1971-05-01
From analysis of a series of vibrational spectra of ir energy absorption and laser Raman, an attempt is made to interpret solid solution hardening from an atomistic point of view for the system CaF(2)/SrF(2). It is shown to be caused by the combined action of three atomic characteristics, i.e., their changes as a function of composition. They are deformation of the atomic coordination polyhedrons, overlap of the outer electron shells of the atom pairs, and the ratio of the ionic to covalent share of binding. A striking nonlinear behavior of the three characteristics, as a function of composition, gives maximum atomic bond strength to the 55/45 position of the system CaF(2)/SrF(2), in agreement with the measured data of the solid solution hardening. The curve for atomic bond strength, derived from the three characteristics, is almost identical to the curve for measured microhardness data. This result suggests that the atomistic interpretation, put forward in this paper, is correct.
Photon propagation function: spectral analysis of its asymptotic form.
Schwinger, J
1974-08-01
The physical attitudes of source theory, displacing those of renormalized, perturbative, operator field theory, are used in a simple discussion of the asymptotic behavior of the photon propagation function. A guiding principle is the elementary consistency requirement that, under circumstances where a physical parameter cannot be accurately measured, no sensitivity to its precise value can enter the description of those circumstances. The mathematical tool is the spectral representation of the propagation function, supplemented by an equivalent phase representation. The Gell-Mann-Low equation is recovered, but with their function now interpreted physically as the spectral weight function. A crude inequality is established for the latter, which helps in interpolating between the initial rising behavior and the ultimate zero at infinite mass. There is a brief discussion of the aggressive source theory viewpoint that denies the existence of a "bare charge".
Multivariate Spectral Analysis to Extract Materials from Multispectral Data
1993-09-01
highest omm* &Poin I1w v~ ovaw~ to be agricultural fields. Their spectral behavior and &s mat" V4 jr4wmwg I ewo be understood by referring to Appendi*x A...unoway-U 15 Swamp-A ____ Urbee-D QUMt. Urbain -V Aim__ j Average)et Using the 20 otining classes rim dmsume4 (ClaM. ItWlik- ifwm *&.,m MAeW* all 5
Perturbative analysis of spectral singularities and their optical realizations
Mostafazadeh, Ali; Rostamzadeh, Saber
2012-01-01
We develop a perturbative method of computing spectral singularities of a Schrodinger operator defined by a general complex potential that vanishes outside a closed interval. These can be realized as zero-width resonances in optical gain media and correspond to a lasing effect that occurs at the threshold gain. Their time-reversed copies yield coherent perfect absorption of light that is also known as antilasing. We use our general results to establish the exactness of the nth-order perturbat...
Spectral analysis of dike-induced earthquakes in Afar, Ethiopia
Tepp, Gabrielle; Ebinger, Cynthia J.; Yun, Sang-Ho
2016-04-01
Shallow dike intrusions may be accompanied by fault slip above the dikes, a superposition which complicates seismic and geodetic data analyses. The diverse volcano-tectonic and low-frequency local earthquakes accompanying the 2005-2010 large-volume dike intrusions in the Dabbahu-Manda Hararo rift (Afar), some with fault displacements of up to 3 m at the surface, provide an opportunity to examine the relations among the earthquakes, dike intrusions, and surface ruptures. We apply the frequency index (FI) method to characterize the spectra of swarm earthquakes from six of the dikes. These earthquakes often have broad spectra with multiple peaks, making the usual peak frequency classification method unreliable. Our results show a general bimodal character with high FI earthquakes associated with deeper dikes (top > 3 km subsurface) and low FI earthquakes associated with shallow dikes, indicating that shallow dikes result in earthquakes with more low-frequency content and larger-amplitude surface waves. Low FI earthquakes are more common during dike emplacement, suggesting that interactions between the dike and faults may lead to lower FI. Taken together, likely source processes for low FI earthquakes are shallow hypocenters (<3 km) possibly with surface rupture, slow rupture velocities, and interactions with dike fluids. Strong site effects also heavily influence the earthquake spectral content. Additionally, our results suggest a continuum of spectral responses, implying either that impulsive volcano-tectonic earthquakes and the unusual, emergent earthquakes have similar source processes or that simple spectral analyses, such as FI, cannot distinguish different source processes.
Analysis of Strehl ratio limit with superresolution binary phase filters
Vidal F.Canales; Pedro J.Valle; Manuel P.Cagigal
2016-01-01
Several pupil filtering techniques have been developed in the last few years to obtain transverse superresolution (a narrower point spread function core).Such a core decrease entails two relevant limitations:a decrease of the peak intensity and an increase of the sidelobe intensity.Here,we calculate the Strehl ratio as a function of the core size for the most used binary phase filters.Furthermore,we show that this relation approaches the fundamental limit of the attainable Strehl ratio at the focal plane for any filter.Finally,we show the calculation of the peak-to-sidelobe ratio in order to check the system viability in every application.
Lee, Woo-Jin; Kang, Se-Ryong; Choi, Soon-Chul; Lee, Sam-Sun; Heo, Min-Suk; Huh, Kyung-Hoe; Yi, Won-Jin
2016-07-01
The objective of this study was to develop a spectral CT system using a photon counting detector and to decompose materials by applying a multiple discriminant analysis (MDA) to the energy-dependent attenuation coefficient ratios. We imaged cylindrical phantoms of Polymethyl methacrylate (PMMA) with four holes filled with calcium chloride, iodine, and gold nanoparticle contrast agents. The attenuation coefficients were measured via reconstructed multi-energy images, and the linear attenuation ratio was used for material identification. The MDA projection matrix, determined from training phantoms, was used to identify the four materials in the testing phantoms. For quantification purposes, the relationships between the attenuation coefficients at multiple energy bins and the concentrations were characterized by using the least-squares method for each material. The mean identification accuracy for each of the three materials were 0.94 ± 0.09 for iodine, 0.96 ± 0.07 for gold nanoparticles, and 0.92 ± 0.05 for calcium chloride. The mean quantification errors were 1.90 ± 1.58% for iodine, 3.85 ± 3.13% for gold nanoparticle, and 3.40 ± 2.62% for calcium chloride. The developed multi-energy CT system based on the photon-counting detector with MDA can precisely decompose the four materials.
Analysis Si/Al ratio in zeolites type FAU by laser induced breakdown spectroscopy (LIBS)
Contreras, W. A.; Cabanzo, R.; Mejía-Ospino, E.
2011-01-01
In this work, Laser Induced Breakdown Spectroscopy (LIBS) is used to determine the Si/Al ratio of Zeolite type Y. The catalytic activity of zeolite is strongly dependent of the Si/Al ratio. We have used Si lines in the spectral region between 245-265 nm to determine temperature of the plasma generated on pelletized sample of zeolite, and stoichiometry relation between Si and Al.
Data Adaptive Spectral Analysis of Unsteady Leakage Flow in an Axial Turbine
Konstantinos G. Barmpalias
2012-01-01
Full Text Available A data adaptive spectral analysis method is applied to characterize the unsteady loss generation in the leakage flow of an axial turbine. Unlike conventional spectral analysis, this method adapts a model dataset to the actual data. The method is illustrated from the analysis of the unsteady wall pressures in the labyrinth seal of an axial turbine. Spectra from the method are shown to be in good agreement with conventional spectral estimates. Furthermore, the spectra using the method are obtained with data records that are 16 times shorter than for conventional spectral analysis, indicating that the unsteady processes in turbomachines can be studied with substantially shorter measurement schedules than is presently the norm.
Spectral analysis of heart rate and blood pressure variability in primary Sjogren's syndrome
P.J. Barendregt (Pieternella); J.H.M. Tulen (Joke); A.H. van den Meiracker (Anton); H.M. Markusse
2002-01-01
textabstractBACKGROUND: Autonomic dysfunction has been described in primary Sjogren's syndrome (SS). OBJECTIVE: To investigate the circulatory autonomic regulation in patients with primary SS by power spectral analysis of heart rate and blood pressure variability. METHODS: Forty th
Spectral analysis of heart rate and blood pressure variability in primary Sjogren's syndrome
P.J. Barendregt (Pieternella); J.H.M. Tulen (Joke); A.H. van den Meiracker (Anton); H.M. Markusse
2002-01-01
textabstractBACKGROUND: Autonomic dysfunction has been described in primary Sjogren's syndrome (SS). OBJECTIVE: To investigate the circulatory autonomic regulation in patients with primary SS by power spectral analysis of heart rate and blood pressure variability. METHODS: Forty th
Analysis of isomeric ratios for medium-mass nuclei
Danagulyan, A. S.; Hovhannisyan, G. H.; Bakhshiyan, T. M.; Kerobyan, I. A.
2016-09-01
Values of the isomeric ratios for product nuclei originating from simple charge-exchange reactions were analyzed. The cross sections for the formation of product nuclei in ground and isomeric states were calculated with the aid of the TALYS 1.4 and EMPIRE 3.2 codes. The calculated values of the isomeric ratios were compared with their experimental counterparts taken from the EXFOR database. For the 86,87Y, 94,95,96,99Tc, and 44Sc nuclei, the experimental values of the isomeric ratios exceed the respective calculated values. The nuclei in question feature weak deformations and have high-spin yrast lines and rotational bands. The possible reason behind the discrepancy between theoretical and experimental isomeric ratios is that the decay of yrast states leads with a high probability to the formation of isomeric states of detected product nuclei.
A combined optical/infrared spectral diagnostic analysis of the HH1 jet
Nisini, B; Giannini, T; Massi, F; Eislöffel, J; Podio, L; Ray, T P; Nisini, Brunella; Bacciotti, Francesca; Giannini, Teresa; Massi, Fabrizio; Eisl\\"offel, Jochen; Podio, Linda; Ray, Thomas P.
2005-01-01
Complete flux-calibrated spectra covering the spectral range from 6000 A to 2.5 um have been obtained along the HH1 jet and analysed in order to explore the potential of a combined optical/near-IR diagnostic applied to jets from young stellar objects. Important physical parameters have been derived along the jet using various diagnostic line ratios. This multi-line analysis shows, in each spatially unresolved knot, the presence of zones at different excitation conditions, as expected from the cooling layers behind a shock front. In particular, a density stratification in the jet is evident from ratios of various lines of different critical density. In particular, [FeII] lines originate in a cooling layer located at larger distances from the shock front than that generating the optical lines, where the compression is higher and the temperature is declining. The derived parameters were used to measure the mass flux along the jet, adopting different procedures, the advantages and limitations of which are discuss...
Statistical Analysis of the Spectral Density Estimate Obtained via Coifman Scaling Function
2007-01-01
Spectral density built as Fourier transform of covariance sequence of stationary random process is determining the process characteristics and makes for analysis of it’s structure. Thus, one of the main problems in time series analysis is constructing consistent estimates of spectral density via successive, taken after equal periods of time observations of stationary random process. This article is devoted to investigation of problems dealing with application of wavelet anal...
Spectral analysis of the electroencephalogram in the developing rat.
Bronzino, J D; Siok, C J; Austin, K; Austin-Lafrance, R J; Morgane, P J
1987-10-01
Power spectral measures of the EEG obtained from the frontal cortex and hippocampal formation during different vigilance states in the developing rat have been computed and compared. The most significant ontogenetic changes were observed in the hippocampal power spectra obtained during the vigilance state of REM sleep. These spectral analyses have revealed in the hippocampus: (1) a significant increase in the frequency at which the peak power occurs in the theta-frequency (4-11 Hz) band from 14 to 45 days of age; (2) a decrease in the quality factor of the peak from 14 to 45 days of age; (3) a decrease in the relative power co-ordinate for the center of spectral mass associated with the 0-4-Hz frequency band coupled with an increase in the frequency coordinate of the 4-11-Hz frequency band from 14 to 45 days of age, and; (4) a significant decrease in the average percent relative power associated with the 0-4-Hz frequency band from 14 to 22 days of age. For the EEG obtained from the frontal cortex, the major findings of note were: (1) a dominant contribution of relative power in the 0-4-Hz frequency band which was observed at every age and during every vigilance state tested, and; (2) a significant increase in the average percent relative power associated with this band at 18, 22, and 45 days of age. The results of this study provide a quantitative description of the electroencephalographic (EEG) ontogeny of the hippocampal formation and the frontal cortex in the rat. These ontogenetic changes in EEG activity relate closely to development of the internal circuitry and synaptic maturation in the hippocampal formation and frontal cortex.
Single-sweep spectral analysis of contact heat evoked potentials
Hansen, Tine M; Graversen, Carina; Frøkjaer, Jens B
2015-01-01
-sweep characteristics to identify alterations induced by morphine. METHODS: In a crossover study 15 single-sweep CHEPs were analyzed from 62 electroencephalography electrodes in 26 healthy volunteers before and after administration of morphine or placebo. Each sweep was decomposed by a continuous wavelet transform...... to obtain normalized spectral indices in the delta (0.5-4 Hz), theta (4-8 Hz), alpha (8-12 Hz), beta (12-32 Hz) and gamma (32-80 Hz) bands. The average distribution over all sweeps and channels was calculated for the four recordings for each volunteer, and the two recordings before treatments were assessed...
Spectral Analysis of Certain Schrödinger Operators
Mourad E.H. Ismail
2012-09-01
Full Text Available The J-matrix method is extended to difference and q-difference operators and is applied to several explicit differential, difference, q-difference and second order Askey-Wilson type operators. The spectrum and the spectral measures are discussed in each case and the corresponding eigenfunction expansion is written down explicitly in most cases. In some cases we encounter new orthogonal polynomials with explicit three term recurrence relations where nothing is known about their explicit representations or orthogonality measures. Each model we analyze is a discrete quantum mechanical model in the sense of Odake and Sasaki [J. Phys. A: Math. Theor. 44 (2011, 353001, 47 pages].
Jessica L. O’Connell
2015-12-01
Full Text Available Broad-scale estimates of belowground biomass are needed to understand wetland resiliency and C and N cycling, but these estimates are difficult to obtain because root:shoot ratios vary considerably both within and between species. We used remotely-sensed estimates of two aboveground plant characteristics, aboveground biomass and % foliar N to explore biomass allocation in low diversity freshwater impounded peatlands (Sacramento-San Joaquin River Delta, CA, USA. We developed a hybrid modeling approach to relate remotely-sensed estimates of % foliar N (a surrogate for environmental N and plant available nutrients and aboveground biomass to field-measured belowground biomass for species specific and mixed species models. We estimated up to 90% of variation in foliar N concentration using partial least squares (PLS regression of full-spectrum field spectrometer reflectance data. Landsat 7 reflectance data explained up to 70% of % foliar N and 67% of aboveground biomass. Spectrally estimated foliar N or aboveground biomass had negative relationships with belowground biomass and root:shoot ratio in both Schoenoplectus acutus and Typha, consistent with a balanced growth model, which suggests plants only allocate growth belowground when additional nutrients are necessary to support shoot development. Hybrid models explained up to 76% of variation in belowground biomass and 86% of variation in root:shoot ratio. Our modeling approach provides a method for developing maps of spatial variation in wetland belowground biomass.
Jessica L. O'Connell,; Byrd, Kristin B.; Maggi Kelly,
2015-01-01
Broad-scale estimates of belowground biomass are needed to understand wetland resiliency and C and N cycling, but these estimates are difficult to obtain because root:shoot ratios vary considerably both within and between species. We used remotely-sensed estimates of two aboveground plant characteristics, aboveground biomass and % foliar N to explore biomass allocation in low diversity freshwater impounded peatlands (Sacramento-San Joaquin River Delta, CA, USA). We developed a hybrid modeling approach to relate remotely-sensed estimates of % foliar N (a surrogate for environmental N and plant available nutrients) and aboveground biomass to field-measured belowground biomass for species specific and mixed species models. We estimated up to 90% of variation in foliar N concentration using partial least squares (PLS) regression of full-spectrum field spectrometer reflectance data. Landsat 7 reflectance data explained up to 70% of % foliar N and 67% of aboveground biomass. Spectrally estimated foliar N or aboveground biomass had negative relationships with belowground biomass and root:shoot ratio in both Schoenoplectus acutus and Typha, consistent with a balanced growth model, which suggests plants only allocate growth belowground when additional nutrients are necessary to support shoot development. Hybrid models explained up to 76% of variation in belowground biomass and 86% of variation in root:shoot ratio. Our modeling approach provides a method for developing maps of spatial variation in wetland belowground biomass.
Comparative analysis of liquidity ratios of bankrupt manufacturing companies
Sebastian Tomczak
2014-12-01
Full Text Available Permanent monitoring of the financial condition of the market increases the chances of survival of the company among of increasing competition in the market. Integrated models are used in the evaluation of corporate bankruptcy. The author has analyzed five liquidity ratios (which have a predictive characteristics of bankrupt and operating companies in the manufacturing sector in the period 2007-2012. In order to reflect changes in the financial condition of the examined companies, the author has analyzed the above-mentioned indicators during the year prior to bankruptcy. This article has attempted to designate the range limit of the liquidity ratios, below or above which there is over liquidity or the lack of liquidity in the manufacturing sector. The limit values were established for three analyzed indicators. However, for two liquidity ratios it was difficult to specify its limits values because of its positive values (caused by selling fixed assets by insolvent companies.
MR PRISM - Spectral Analysis Tool for the CRISM
Brown, Adrian J
2014-01-01
We describe a computer application designed to analyze hyperspectral data collected by the Compact Infrared Spectrometer for Mars (CRISM). The application links the spectral, imaging and mapping perspectives on the eventual CRISM dataset by presenting the user with three different ways to analyze the data. One of the goals when developing this instrument is to build in the latest algorithms for detection of spectrally compelling targets on the surface of the Red Planet, so they may be available to the Planetary Science community without cost and with a minimal learning barrier to cross. This will allow the Astrobiology community to look for targets of interest such as hydrothermal minerals, sulfate minerals and hydrous minerals and be able to map the extent of these minerals using the most up-to-date and effective algorithms. The application is programmed in Java and will be made available for Windows, Mac and Linux platforms. Users will be able to embed Groovy scripts into the program in order to extend its ...
Stellar and wind parameters of massive stars from spectral analysis
Araya, I.; Curé, M.
2017-07-01
The only way to deduce information from stars is to decode the radiation it emits in an appropriate way. Spectroscopy can solve this and derive many properties of stars. In this work we seek to derive simultaneously the stellar and wind characteristics of A and B supergiant stars. Our stellar properties encompass the effective temperature, the surface gravity, the stellar radius, the micro-turbulence velocity, the rotational velocity and, finally, the chemical composition. For wind properties we consider the mass-loss rate, the terminal velocity and the line-force parameters (α, k and δ) obtained from the standard line-driven wind theory. To model the data we use the radiative transport code Fastwind considering the newest hydrodynamical solutions derived with Hydwind code, which needs stellar and line-force parameters to obtain a wind solution. A grid of spectral models of massive stars is created and together with the observed spectra their physical properties are determined through spectral line fittings. These fittings provide an estimation about the line-force parameters, whose theoretical calculations are extremely complex. Furthermore, we expect to confirm that the hydrodynamical solutions obtained with a value of δ slightly larger than ˜ 0.25, called δ-slow solutions, describe quite reliable the radiation line-driven winds of A and late B supergiant stars and at the same time explain disagreements between observational data and theoretical models for the Wind-Momentum Luminosity Relationship (WLR).
Kim, Dohyeong; Kim, Ji Hoon; Jun, Hyunsung David; Woo, Jong-Hak; Lee, Hyung Mok; Lee, Myung Gyoon; Nakagawa, Takao; Matsuhara, Hideo; Wada, Takehiko; Oyabu, Shinki; Takagi, Toshinobu; Ohyama, Youichi; Lee, Seong-Kook
2015-01-01
We present 2.5-5.0 $\\mu$m spectra of 83 nearby ($0.002\\,<\\,z\\,<\\,0.48$) and bright ($K<14$mag) type-1 active galactic nuclei (AGNs) taken with the Infrared Camera (IRC) on board $\\it{AKARI}$. The 2.5-5.0 $\\mu$m spectral region contains emission lines such as Br$\\beta$ (2.63 $\\mu$m), Br$\\alpha$ (4.05 $\\mu$m), and polycyclic aromatic hydrocarbons (PAH; 3.3 $\\mu$m), which can be used for studying the black hole (BH) masses and star formation activities in the host galaxies of AGNs. The spectral region also suffers less dust extinction than in the ultra violet (UV) or optical wavelengths, which may provide an unobscured view of dusty AGNs. Our sample is selected from bright quasar surveys of Palomar-Green (PG) and SNUQSO, and AGNs with reverberation-mapped BH masses from Peterson et al. (2004). Using 11 AGNs with reliable detection of Brackett lines, we derive the Brackett-line-based BH mass estimators. We also find that the observed Brackett line ratios can be explained with the commonly adopted physica...
Prabawa Arwananda, Alif; Aryaseta, Bagas; Dezulfakar, Hafidz; Fatahillah, Yosar; Pandu Gya Nur Rochman, Juan
2017-04-01
Based on field study, Sedati Mud Volcano located in a line with Gunung Anyar Mud Volcano and occurred by increased pressure in the compression area and rapid loss of gas. The combination of both fast-growing constructions of infrastructures and the presence of the mud volcanoes brings new challenges in Sidoarjo city. The purpose of this scientific research is to determine the sedimentary thickness around Sedati mud volcano. Only a few data show real amplitude spectrum, which represent high contrast impedance. At some point, there are several peaks indicating the presence of contrast impedance between layers. Based on 20 processed data, Sedati Mud Volcano has a 30 - 70m engineering bedrock thickness and natural frequency between 0.5 until 14.4 Hz. The enhancement of natural frequency tends to occur along decrement of layer thickness in the upper basement layer. The result shows the natural frequency parameter and its amplification is slightly variated around Sedati Mud Volcano, as caused by sedimentary lateral depth variation and/or the presence of variation on existing rock. Further analysis indicates a fault inside the area of mud volcano as possible reason behind the occurring mudflow.
Military target detection using spectrally modeled algorithms and independent component analysis
Tiwari, Kailash Chandra; Arora, Manoj K.; Singh, Dharmendra; Yadav, Deepti
2013-02-01
Most military targets of strategic importance are very small in size. Though some of them may get spatially resolved, most cannot be detected due to lack of adequate spectral resolution. Hyperspectral data, acquired over hundreds of narrow contiguous wavelength bands, are extremely suitable for most military target detection applications. Target detection, however, still remains complicated due to a host of other issues. These include, first, the heavy volume of hyperspectral data, which leads to computational complexities; second, most materials in nature exhibit spectral variability and remain unpredictable; and third, most target detection algorithms are based on spectral modeling and availability of a priori target spectra is an essential requirement, a condition difficult to meet in practice. Independent component analysis (ICA) is a new evolving technique that aims at finding components that are statistically independent or as independent as possible. It does not have any requirement of a priori availability of target spectra and is an attractive alternative. This paper, presents a study of military target detection using four spectral matching algorithms, namely, orthogonal subspace projection (OSP), constrained energy minimisation, spectral angle mapper and spectral correlation mapper, four anomaly detection algorithms, namely, OSP anomaly detector (OSPAD), Reed-Xiaoli anomaly detector (RXD), uniform target detector (UTD), a combination of RXD-UTD. The performances of these spectrally modeled algorithms are then also compared with ICA using receiver operating characteristic analysis. The superior performance of ICA indicates that it may be considered a viable alternative for military target detection.
[Estimation of Hunan forest carbon density based on spectral mixture analysis of MODIS data].
Yan, En-ping; Lin, Hui; Wang, Guang-xing; Chen, Zhen-xiong
2015-11-01
With the fast development of remote sensing technology, combining forest inventory sample plot data and remotely sensed images has become a widely used method to map forest carbon density. However, the existence of mixed pixels often impedes the improvement of forest carbon density mapping, especially when low spatial resolution images such as MODIS are used. In this study, MODIS images and national forest inventory sample plot data were used to conduct the study of estimation for forest carbon density. Linear spectral mixture analysis with and without constraint, and nonlinear spectral mixture analysis were compared to derive the fractions of different land use and land cover (LULC) types. Then sequential Gaussian co-simulation algorithm with and without the fraction images from spectral mixture analyses were employed to estimate forest carbon density of Hunan Province. Results showed that 1) Linear spectral mixture analysis with constraint, leading to a mean RMSE of 0.002, more accurately estimated the fractions of LULC types than linear spectral and nonlinear spectral mixture analyses; 2) Integrating spectral mixture analysis model and sequential Gaussian co-simulation algorithm increased the estimation accuracy of forest carbon density to 81.5% from 74.1%, and decreased the RMSE to 5.18 from 7.26; and 3) The mean value of forest carbon density for the province was 30.06 t · hm(-2), ranging from 0.00 to 67.35 t · hm(-2). This implied that the spectral mixture analysis provided a great potential to increase the estimation accuracy of forest carbon density on regional and global level.
[Decoloring and spectral properties analysis of innoxious ultraviolet absorbents].
Fang, Yi-Wen; Ni, Wen-Xiu; Huang, Chong; Xue, Liang; Yu, Lin
2006-07-01
The ultraviolet absorbent extracted from mango leaves, was discolored by some decoloring agent. Then the spectral properties of the discolored ultraviolet absorbents were analyzed. The discolored method of ultraviolet absorbent was studied by comparing one with the others. The results showed that the discoloring effect was satisfactory by using active carbon, H2O2, citric acid, and oxalic acid as decoloring agent. Specially, when oxalic acid was used as decoloring agent, the color of the production was slight, the rate of production was high, and the absorption effect of ultraviolet ray was well. When the concentration of the ultraviolet absorbent solution is 0.5% (w/w), the ultraviolet ray transmission was smaller than 0.3% in 200-370 nm, and it increased slightly from 370 nm. There was a maximum value at 400 nm, approaching 12%.
Cool DZ white dwarfs I: Identification and spectral analysis
Hollands, M. A.; Koester, D.; Alekseev, V.; Herbert, E. L.; Gänsicke, B. T.
2017-01-01
White dwarfs with metal lines in their spectra act as signposts for post-main sequence planetary systems. Searching the Sloan Digital Sky Survey (SDSS) data release 12, we have identified 231 cool (absorption, extending the DZ cooling sequence to both higher metal abundances, lower temperatures, and hence longer cooler ages. Of these 231 systems, 104 are previously unknown white dwarfs. Compared with previous work, our spectral fitting uses improved model atmospheres with updated line profiles and line-lists, which we use to derive effective temperatures and abundances for up to 8 elements. We also determine spectroscopic distances to our sample, identifying two halo-members with tangential space-velocities >300 km s-1. The implications of our results on remnant planetary systems are to be discussed in a separate paper.
Marfin, Yu S; Rumyantsev, E V
2014-09-15
Photophysical characteristics of several alkylated dipyrrin Zn(II) complexes in organic solvents were analyzed. Relations between spectral properties of complexes and physical-chemical parameters of solvents were determined with the use of linear regression analysis method. Each solvent parameter contribution in investigated spectral characteristics was estimated. Spectral properties of complexes under study depend on the specific interactions of zinc with the solvent molecules by specific axial coordination. Increasing of alkyl substitution lead to the bathochromic shifts in spectra due to the positive induction effect of alkyl groups.
Marfin, Yu. S.; Rumyantsev, E. V.
2014-09-01
Photophysical characteristics of several alkylated dipyrrin Zn(II) complexes in organic solvents were analyzed. Relations between spectral properties of complexes and physical-chemical parameters of solvents were determined with the use of linear regression analysis method. Each solvent parameter contribution in investigated spectral characteristics was estimated. Spectral properties of complexes under study depend on the specific interactions of zinc with the solvent molecules by specific axial coordination. Increasing of alkyl substitution lead to the bathochromic shifts in spectra due to the positive induction effect of alkyl groups.
[Research on signal processing for water quality monitoring based on continuous spectral analysis].
Wei, Kang-lin; Chen, Ming; Wen, Zhi-yu; Xie, Yin-ke
2014-12-01
Based on continuous spectrum analysis, the mathematical model for spectrum signal was established. And the spectrum signal's systematic error processing method based on the invariance of the ratio of the light intensities at any two wavelengths in the range of continuous spectrum was put forward. Combined with wavelet multi-resolution filtering noise processing techniques, the background interference processing method was established based on the spectral characteristics of the measured water quality parameter. These signal processing methods were applied to our independently developed multi-parameter water quality monitoring instrument to on-line measure COD (chemical oxygen demand), six valence chromium and anionic surfactant in the normative and actual environmental water samples, and the monitoring instrument had good repeatability (10%) and high accuracy (±10%) to meet the technical requirements of national environmental protection standards, which was verified by the contrast experiment with China national standard analysis method for determination of the three water quality parameter. The results showed that the researched signal processing methods were able to effectively reduce the spectrum signal's systematic error and the interference from noise and background, which was very important to improve the water quality monitoring instrument's technical function.
RF spectral analysis for characterisation of mode-locked regimes in fibre lasers
Ivanenko, Alexey V.; Kobtsev, Sergey M.; Kokhanovskiy, Alexey; Smirnov, Sergey V.
2016-10-01
In this work, we present our results of RF spectral analysis applied to mode-locked lasers and propose a method of qualitative assessment of mode-locked operation, which allows differentiation of individual generation regimes by a parameter calculated from RF spectra of the fundamental and the n-th radiation harmonics. The proposed parameter is derived both from the signal-to-noise ratio and from width and amount of additional noise present in RF spectrum of inter-mode beats at the fundamental pulse repetition frequency and its harmonic. This work presents analysis of energy fluctuations and temporal instability of pulse train period for different regimes of pulse generation in Yb fibre laser mode locked due to nonlinear polarization evolution. The paper shows that energy fluctuations of single-scale ("conventional") pulses is about 1.6%, whereas for double-scale pulses energy fluctuations amount to 11.5%. Temporal instability of double-scale pulse train period is 1.5 times higher in comparison with single-scale pulse train period.
Posada-Quintero, Hugo F; Florian, John P; Orjuela-Cañón, Álvaro D; Chon, Ki H
2016-09-01
Time-domain indices of electrodermal activity (EDA) have been used as a marker of sympathetic tone. However, they often show high variation between subjects and low consistency, which has precluded their general use as a marker of sympathetic tone. To examine whether power spectral density analysis of EDA can provide more consistent results, we recently performed a variety of sympathetic tone-evoking experiments (43). We found significant increase in the spectral power in the frequency range of 0.045 to 0.25 Hz when sympathetic tone-evoking stimuli were induced. The sympathetic tone assessed by the power spectral density of EDA was found to have lower variation and more sensitivity for certain, but not all, stimuli compared with the time-domain analysis of EDA. We surmise that this lack of sensitivity in certain sympathetic tone-inducing conditions with time-invariant spectral analysis of EDA may lie in its inability to characterize time-varying dynamics of the sympathetic tone. To overcome the disadvantages of time-domain and time-invariant power spectral indices of EDA, we developed a highly sensitive index of sympathetic tone, based on time-frequency analysis of EDA signals. Its efficacy was tested using experiments designed to elicit sympathetic dynamics. Twelve subjects underwent four tests known to elicit sympathetic tone arousal: cold pressor, tilt table, stand test, and the Stroop task. We hypothesize that a more sensitive measure of sympathetic control can be developed using time-varying spectral analysis. Variable frequency complex demodulation, a recently developed technique for time-frequency analysis, was used to obtain spectral amplitudes associated with EDA. We found that the time-varying spectral frequency band 0.08-0.24 Hz was most responsive to stimulation. Spectral power for frequencies higher than 0.24 Hz were determined to be not related to the sympathetic dynamics because they comprised less than 5% of the total power. The mean value of time
Spatio-spectral analysis of ionization times in high-harmonic generation
Soifer, Hadas, E-mail: hadas.soifer@weizmann.ac.il [Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 76100 (Israel); Dagan, Michal; Shafir, Dror; Bruner, Barry D. [Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 76100 (Israel); Ivanov, Misha Yu. [Department of Physics, Imperial College London, South Kensington Campus, SW7 2AZ London (United Kingdom); Max-Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, Max-Born-Strasse 2A, D-12489 Berlin (Germany); Serbinenko, Valeria; Barth, Ingo; Smirnova, Olga [Max-Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, Max-Born-Strasse 2A, D-12489 Berlin (Germany); Dudovich, Nirit [Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 76100 (Israel)
2013-03-12
Graphical abstract: A spatio-spectral analysis of the two-color oscillation phase allows us to accurately separate short and long trajectories and reconstruct their ionization times. Highlights: ► We perform a complete spatio-spectral analysis of the high harmonic generation process. ► We analyze the ionization times across the entire spatio-spectral plane of the harmonics. ► We apply this analysis to reconstruct the ionization times of both short and long trajectories. - Abstract: Recollision experiments have been very successful in resolving attosecond scale dynamics. However, such schemes rely on the single atom response, neglecting the macroscopic properties of the interaction and the effects of using multi-cycle laser fields. In this paper we perform a complete spatio-spectral analysis of the high harmonic generation process and resolve the distribution of the subcycle dynamics of the recolliding electron. Specifically, we focus on the measurement of ionization times. Recently, we have demonstrated that the addition of a weak, crossed polarized second harmonic field allows us to resolve the moment of ionization (Shafir, 2012) [1]. In this paper we extend this measurement and perform a complete spatio-spectral analysis. We apply this analysis to reconstruct the ionization times of both short and long trajectories showing good agreement with the quantum path analysis.
ANALYSIS OF SPECTRAL CHARACTERISTICS AMONG DIFFERENT SENSORS BY USE OF SIMULATED RS IMAGES
无
2000-01-01
This research, by use of RS image-simulating method, simulated apparent reflectance images at sensor level and ground-reflectance images of SPOT-HRV,CBERS-CCD,Landsat-TM and NOAA14-AVHRR' s corresponding bands. These images were used to analyze sensor's differences caused by spectral sensitivity and atmospheric impacts. The differences were analyzed on Normalized Difference Vegetation Index(NDVI). The results showed that the differences of sensors' spectral characteristics cause changes of their NDVI and reflectance. When multiple sensors' data are applied to digital analysis, the error should be taken into account. Atmospheric effect makes NDVI smaller, and atn~pheric correction has the tendency of increasing NDVI values. The reflectance and their NDVIs of different sensors can be used to analyze the differences among sensor' s features. The spectral analysis method based on RS simulated images can provide a new way to design the spectral characteristics of new sensors.
Spectral analysis of growing graphs a quantum probability point of view
Obata, Nobuaki
2017-01-01
This book is designed as a concise introduction to the recent achievements on spectral analysis of graphs or networks from the point of view of quantum (or non-commutative) probability theory. The main topics are spectral distributions of the adjacency matrices of finite or infinite graphs and their limit distributions for growing graphs. The main vehicle is quantum probability, an algebraic extension of the traditional probability theory, which provides a new framework for the analysis of adjacency matrices revealing their non-commutative nature. For example, the method of quantum decomposition makes it possible to study spectral distributions by means of interacting Fock spaces or equivalently by orthogonal polynomials. Various concepts of independence in quantum probability and corresponding central limit theorems are used for the asymptotic study of spectral distributions for product graphs. This book is written for researchers, teachers, and students interested in graph spectra, their (asymptotic) spectr...
Near-Infrared Hyper-spectral Image Analysis of Astaxanthin Concentration in Fish Feed Coating
Ljungqvist, Martin Georg; Ersbøll, Bjarne Kjær; Kobayashi, K.;
2012-01-01
The aim of this study was to investigate the possibility of predicting concentration levels of synthetic astaxanthin coating of aquaculture feed pellets by hyper-spectral image analysis in the near infra-red (NIR) range and optical filter design. The imaging devices used were a Videometer...... for prediction of the concentration level. The results show that it is possible to predict the level of synthetic astaxanthin coating using either hyper-spectral imaging or three bandpass filters (BPF)....
Cho, Moses A
2009-08-01
Full Text Available architecture. Several mapping methods are applied in remote sensing to quantify species or vegetation community distribution at the local to regional scale. The most commonly used methods include maximum likelihood, spectral mixture analysis (SMA)[1...] and spectral angle mapper (SAM)[2]. The application of some of these methods including SAM and SMA has become popular with the advent of hyperspectral remote sensing. SAM determines the degree of similarity between two spectra by treating the spectra...
Spectral Analysis of Transition Operators, Automata Groups and Translation in BBS
Kato, Tsuyoshi; Tsujimoto, Satoshi; Zuk, Andrzej
2016-06-01
We give the automata that describe time evolution rules of the box-ball system with a carrier. It can be shown by use of tropical geometry that such systems are ultradiscrete analogues of KdV equation. We discuss their relation with the lamplighter group generated by an automaton. We present spectral analysis of the stochastic matrices induced by these automata and verify their spectral coincidence.
Technical Training on High-Order Spectral Analysis and Thermal Anemometry Applications
Maslov, A. A.; Shiplyuk, A. N.; Sidirenko, A. A.; Bountin, D. A.
2003-01-01
The topics of thermal anemometry and high-order spectral analyses were the subject of the technical training. Specifically, the objective of the technical training was to study: (i) the recently introduced constant voltage anemometer (CVA) for high-speed boundary layer; and (ii) newly developed high-order spectral analysis techniques (HOSA). Both CVA and HOSA are relevant tools for studies of boundary layer transition and stability.
Comsa, D.C. E-mail: comsadc@mcmaster.ca; Prestwich, W.V.; McNeill, F.E.; Byun, S.H
2004-12-01
The toxic effects of aluminum are cumulative and result in painful forms of renal osteodystrophy, most notably adynamic bone disease and osteomalacia, but also other forms of disease. The Trace Element Group at McMaster University has developed an accelerator-based in vivo procedure for detecting aluminum body burden by neutron activation analysis (NAA). Further refining of the method was necessary for increasing its sensitivity. In this context, the present study proposes an improved algorithm for data analysis, based on spectral decomposition. A new minimum detectable limit (MDL) of (0.7{+-}0.1) mg Al was reached for a local dose of (20{+-}1) mSv. The study also addresses the feasibility of a new data acquisition technique, the electronic rejection of the coincident events detected by a NaI(Tl) system. It is expected that the application of this technique, together with spectral decomposition analysis, would provide an acceptable MDL for the method to be valuable in a clinical setting.
赵恒谦; 张立福; 吴太夏; 黄长平
2013-01-01
矿物丰度含量的精确分析是高光谱遥感技术定量分析中的难点.将化学领域的比值导数光谱算法进行总结,将其引入遥感反射率光谱分析,提出了基于线性光谱混合模型的比值导数光谱解混模型,并利用石膏和绿帘石粉末混合物进行了模型的精度分析.实验结果表明,矿物粉末混合物在不同波段其光谱混合特性有所不同,其中部分波段有较强的线性混合特征.采用部分强线性混合波段进行光谱解混,可以取得比全波段解混算法更好的结果.比值导数法光谱解混模型简洁,可以得到高精度的矿物成分反演结果,对于固定端元组成的混合光谱定量分析有较大潜力.%The precise analysis of mineral abundance is a key difficulty in hyperspectral remote sensing research. In the present paper, based on linear spectral mixture model, the derivative of ratio spectroscopy (DRS) was introduced for spectral unmixing of visible to short-wave infrared (Vis-SWIR; 0. 4～2. 5 μm) reflectance data. The mixtures of different proportions of plaster and allochite were analyzed to estimate the accuracy of the spectral unmixing model based on DRS. For the best 5 strong linear bands, the Pearson correlation coefficient (PCC) of the abundances and the actual abundances were higher than 99. 9%, while the root mean square error (RMSE) is less than 2. 2%. The result shows that the new spectral unmixing model based on DRS is simple, of rigorous mathematical proof, and highly precise. It has a great potential in high-precision quantitative analysis of spectral mixture with fixed endmembers.
Stratified spectral mixture analysis of medium resolution imagery for impervious surface mapping
Sun, Genyun; Chen, Xiaolin; Ren, Jinchang; Zhang, Aizhu; Jia, Xiuping
2017-08-01
Linear spectral mixture analysis (LSMA) is widely employed in impervious surface estimation, especially for estimating impervious surface abundance in medium spatial resolution images. However, it suffers from a difficulty in endmember selection due to within-class spectral variability and the variation in the number and the type of endmember classes contained from pixel to pixel, which may lead to over or under estimation of impervious surface. Stratification is considered as a promising process to address the problem. This paper presents a stratified spectral mixture analysis in spectral domain (Sp_SSMA) for impervious surface mapping. It categorizes the entire data into three groups based on the Combinational Build-up Index (CBI), the intensity component in the color space and the Normalized Difference Vegetation Index (NDVI) values. A suitable endmember model is developed for each group to accommodate the spectral variation from group to group. The unmixing into the associated subset (or full set) of endmembers in each group can make the unmixing adaptive to the types of endmember classes that each pixel actually contains. Results indicate that the Sp_SSMA method achieves a better performance than full-set-endmember SMA and prior-knowledge-based spectral mixture analysis (PKSMA) in terms of R, RMSE and SE.
A new perspective on hospital financial ratio analysis.
Zeller, T L; Stanko, B B; Cleverley, W O
1997-11-01
Using audit financial data in a study of 2,189 not-for-profit hospitals for the period 1989-1992, six financial characteristics of performance were defined. These characteristics are profitability factor, fixed-asset efficiency, capital structure, fixed-asset age, working capital efficiency, and liquidity. The statistical output also shows the specific sets of financial ratios that can be used to measure the six characteristics of hospital performance. The results of this study can be beneficial to healthcare financial managers, hospital boards, policy groups, and other relevant entities because it affords them a clear understanding of an institution's financial performance.
Image Enhancement by Spectral Ratioing,
1980-06-01
images et Vacquisition d’objectif dans 1’ infrarouge ", DREV R-4050/76, avril 1976, NON CIASSIFIE. UNCLASSIFIED 16 7. Sdvigny, L., "Simulation d’un syst...me d’acquisition automatique d’objectif infrarouge dans un contexte sol-sol", DREV R-4081/77, juin 1977, NON CIASSIFIE. 8. S6vigny, L., "La...reconnaissance de forme et I’acquisition d’objectif en infrarouge : Nouvel algorithme de detection", DREV R-4099/78, mars 1979, NON CEASSIFIE. 9. Panda, D.P
Infrared Spectroscopy of Explosives Residues: Measurement Techniques and Spectral Analysis
Phillips, Mark C.; Bernacki, Bruce E.
2015-03-11
Infrared laser spectroscopy of explosives is a promising technique for standoff and non-contact detection applications. However, the interpretation of spectra obtained in typical standoff measurement configurations presents numerous challenges. Understanding the variability in observed spectra from explosives residues and particles is crucial for design and implementation of detection algorithms with high detection confidence and low false alarm probability. We discuss a series of infrared spectroscopic techniques applied toward measuring and interpreting the reflectance spectra obtained from explosives particles and residues. These techniques utilize the high spectral radiance, broad tuning range, rapid wavelength tuning, high scan reproducibility, and low noise of an external cavity quantum cascade laser (ECQCL) system developed at Pacific Northwest National Laboratory. The ECQCL source permits measurements in configurations which would be either impractical or overly time-consuming with broadband, incoherent infrared sources, and enables a combination of rapid measurement speed and high detection sensitivity. The spectroscopic methods employed include standoff hyperspectral reflectance imaging, quantitative measurements of diffuse reflectance spectra, reflection-absorption infrared spectroscopy, microscopic imaging and spectroscopy, and nano-scale imaging and spectroscopy. Measurements of explosives particles and residues reveal important factors affecting observed reflectance spectra, including measurement geometry, substrate on which the explosives are deposited, and morphological effects such as particle shape, size, orientation, and crystal structure.
An analysis of gamma-ray burst spectral break models
Zhang, B; Zhang, Bing; Meszaros, Peter
2002-01-01
Typical gamma-ray burst spectra are characterized by a spectral break, Ep, which for bright BATSE bursts is found to be narrowly clustered around 300 keV. Recently identified X-ray flashes, which may account for a significant portion of the whole GRB population, seem to extend the Ep distribution to a broader range below 40 keV. On the other hand, within the cosmological fireball model, the issues concerning the dominant energy ingredient of the fireball as well as the location of the GRB emission site are not unambiguously settled, leading to several variants of the fireball model. Here we analyze these models within a unified framework, and critically reexamine the Ep predictions in the various model variants, focusing on their predicted properties. Attention is focused on the ability of the models to match a narrowness of the Ep distribution, and the correlations among Ep and some other measurable observables, as well as the effect of extending these properties to X-ray flash sources. These model propertie...
Spectral analysis of Kepler SPB and Beta Cep candidate stars
Lehmann, H; Semaan, T; Gutiérrez, J; Smalley, B; Briquet, M; Shulyak, D; Tsymbal, V; de Cat, P
2010-01-01
We determine the fundamental parameters of SPB and Beta Cep candidate stars observed by the Kepler satellite mission and estimate the expected types of non-radial pulsators by comparing newly obtained high-resolution spectra with synthetic spectra computed on a grid of stellar parameters assuming LTE and check for NLTE effects for the hottest stars. For comparison, we determine Teff independently from fitting the spectral energy distribution of the stars obtained from the available photometry. We determine Teff, log(g), micro-turbulent velocity, vsin(i), metallicity, and elemental abundance for 14 of the 16 candidate stars, two of the stars are spectroscopic binaries. No significant influence of NLTE effects on the results could be found. For hot stars, we find systematic deviations of the determined effective temperatures from those given in the Kepler Input Catalogue. The deviations are confirmed by the results obtained from ground-based photometry. Five stars show reduced metallicity, two stars are He-stro...
Spectral analysis and markov switching model of Indonesia business cycle
Fajar, Muhammad; Darwis, Sutawanir; Darmawan, Gumgum
2017-03-01
This study aims to investigate the Indonesia business cycle encompassing the determination of smoothing parameter (λ) on Hodrick-Prescott filter. Subsequently, the components of the filter output cycles were analyzed using a spectral method useful to know its characteristics, and Markov switching regime modeling is made to forecast the probability recession and expansion regimes. The data used in the study is real GDP (1983Q1 - 2016Q2). The results of the study are: a) Hodrick-Prescott filter on real GDP of Indonesia to be optimal when the value of the smoothing parameter is 988.474, b) Indonesia business cycle has amplitude varies between±0.0071 to±0.01024, and the duration is between 4 to 22 quarters, c) the business cycle can be modelled by MSIV-AR (2) but regime periodization is generated this model not perfect exactly with real regime periodzation, and d) Based on the model MSIV-AR (2) obtained long-term probabilities in the expansion regime: 0.4858 and in the recession regime: 0.5142.
Spectral analysis of the Dirac operator on a 3-sphere
Fang, Yan-Long; Vassiliev, Dmitri
2016-01-01
We study the (massless) Dirac operator on a 3-sphere equipped with Riemannian metric. For the standard metric the spectrum is known. In particular, the eigenvalues closest to zero are the two double eigenvalues +3/2 and -3/2. Our aim is to analyse the behaviour of eigenvalues when the metric is perturbed in an arbitrary smooth fashion from the standard one. We derive explicit asymptotic formulae for the two eigenvalues closest to zero. Note that these eigenvalues remain double eigenvalues under perturbations of the metric: they cannot split because of a particular symmetry of the Dirac operator in dimension three (it commutes with the antilinear operator of charge conjugation). Our asymptotic formulae show that in the first approximation our two eigenvalues maintain symmetry about zero and are completely determined by the increment of Riemannian volume. Spectral asymmetry is observed only in the second approximation of the perturbation process. As an example we consider a special family of metrics, the so-cal...
Spectral analysis of hearing protector impulsive insertion loss.
Fackler, Cameron J; Berger, Elliott H; Murphy, William J; Stergar, Michael E
2017-01-01
To characterise the performance of hearing protection devices (HPDs) in impulsive-noise conditions and to compare various protection metrics between impulsive and steady-state noise sources with different characteristics. HPDs were measured per the impulsive test methods of ANSI/ASA S12.42- 2010 . Protectors were measured with impulses generated by both an acoustic shock tube and an AR-15 rifle. The measured data were analysed for impulse peak insertion loss (IPIL) and impulsive spectral insertion loss (ISIL). These impulsive measurements were compared to insertion loss measured with steady-state noise and with real-ear attenuation at threshold (REAT). Tested HPDs included a foam earplug, a level-dependent earplug and an electronic sound-restoration earmuff. IPIL for a given protector varied between measurements with the two impulse noise sources, but ISIL agreed between the two sources. The level-dependent earplug demonstrated level-dependent effects both in IPIL and ISIL. Steady-state insertion loss and REAT measurements tended to provide a conservative estimate of the impulsively-measured attenuation. Measurements of IPIL depend strongly on the source used to measure them, especially for HPDs with less attenuation at low frequencies. ISIL provides an alternative measurement of impulse protection and appears to be a more complete description of an HPD's performance.
Quantitative characterization of surface topography using spectral analysis
Jacobs, Tevis D. B.; Junge, Till; Pastewka, Lars
2017-03-01
Roughness determines many functional properties of surfaces, such as adhesion, friction, and (thermal and electrical) contact conductance. Recent analytical models and simulations enable quantitative prediction of these properties from knowledge of the power spectral density (PSD) of the surface topography. The utility of the PSD is that it contains statistical information that is unbiased by the particular scan size and pixel resolution chosen by the researcher. In this article, we first review the mathematical definition of the PSD, including the one- and two-dimensional cases, and common variations of each. We then discuss strategies for reconstructing an accurate PSD of a surface using topography measurements at different size scales. Finally, we discuss detecting and mitigating artifacts at the smallest scales, and computing upper/lower bounds on functional properties obtained from models. We accompany our discussion with virtual measurements on computer-generated surfaces. This discussion summarizes how to analyze topography measurements to reconstruct a reliable PSD. Analytical models demonstrate the potential for tuning functional properties by rationally tailoring surface topography—however, this potential can only be achieved through the accurate, quantitative reconstruction of the PSDs of real-world surfaces.
Koopmans' Analysis of Chemical Hardness with Spectral-Like Resolution
2013-01-01
Three approximation levels of Koopmans' theorem are explored and applied: the first referring to the inner quantum behavior of the orbitalic energies that depart from the genuine ones in Fock space when the wave-functions' Hilbert-Banach basis set is specified to solve the many-electronic spectra of spin-orbitals' eigenstates; it is the most subtle issue regarding Koopmans' theorem as it brings many critics and refutation in the last decades, yet it is shown here as an irrefutable “observational” effect through computation, specific to any in silico spectra of an eigenproblem; the second level assumes the “frozen spin-orbitals” approximation during the extracting or adding of electrons to the frontier of the chemical system through the ionization and affinity processes, respectively; this approximation is nevertheless workable for great deal of chemical compounds, especially organic systems, and is justified for chemical reactivity and aromaticity hierarchies in an homologue series; the third and the most severe approximation regards the extension of the second one to superior orders of ionization and affinities, here studied at the level of chemical hardness compact-finite expressions up to spectral-like resolution for a paradigmatic set of aromatic carbohydrates. PMID:23970834
Koopmans' Analysis of Chemical Hardness with Spectral-Like Resolution
Mihai V. Putz
2013-01-01
Full Text Available Three approximation levels of Koopmans' theorem are explored and applied: the first referring to the inner quantum behavior of the orbitalic energies that depart from the genuine ones in Fock space when the wave-functions' Hilbert-Banach basis set is specified to solve the many-electronic spectra of spin-orbitals' eigenstates; it is the most subtle issue regarding Koopmans' theorem as it brings many critics and refutation in the last decades, yet it is shown here as an irrefutable “observational” effect through computation, specific to any in silico spectra of an eigenproblem; the second level assumes the “frozen spin-orbitals” approximation during the extracting or adding of electrons to the frontier of the chemical system through the ionization and affinity processes, respectively; this approximation is nevertheless workable for great deal of chemical compounds, especially organic systems, and is justified for chemical reactivity and aromaticity hierarchies in an homologue series; the third and the most severe approximation regards the extension of the second one to superior orders of ionization and affinities, here studied at the level of chemical hardness compact-finite expressions up to spectral-like resolution for a paradigmatic set of aromatic carbohydrates.
Midinfrared spectral investigations of carbonates: Analysis of remotely sensed data
Roush, T.; Pollack, J. B.; Mckay, C. P.
1991-01-01
Recent airborne thermal infrared observations of Mars from the Kuiper Airborne Observatory (KAO) have provided evidence for the presence of carbonates, sulfates, and hydrates. Using the optical properties of calcite and anhydrite, it was estimated that CO3's and SO4's constituted about 1 to 3 and 10 to 15 wt. percent, repectively of the materials composing the atmospheric dust. Using the derived value as an estimate of total CO3 abundance, and making an assumption that the CO3's were uniformly distributed within the Martian regolith, it was estimated that such a CO3 reservoir could contain roughly 2 to 5 bars of CO2. While the results indicate that several volatile-bearing materials are present on Mars, the observations from the KAO are inherently limited in their ability to determine the spatial distributions of these materials. However, previous spacecraft observations of Mars provide both the spectral coverage necessary to identify these materials, as well as the potential for investigating their spatial variability. This has prompted us to pursue a reinvestigation of the Mariner 6 and 7 infrared spectrometer and Mariner 9 infrared interferometer spectrometer observations. The former data have been recently made available in digital format and calibration of wavelengths and intensities are almost complete. Additionally, we are pursuing the derivation of optical constants of more appropriate carbonates and sulfates.
LDA measurements and turbulence spectral analysis in an agitated vessel
Chára Zdeněk
2013-04-01
Full Text Available During the last years considerable improvement of the derivation of turbulence power spectrum from Laser Doppler Anemometry (LDA has been achieved. The irregularly sampled LDA data is proposed to approximate by several methods e.g. Lomb-Scargle method, which estimates amplitude and phase of spectral lines from missing data, methods based on the reconstruction of the auto-correlation function (referred to as correlation slotting technique, methods based on the reconstruction of the time series using interpolation between the uneven sampling and subsequent resampling etc. These different methods were used on the LDA data measured in an agitated vessel and the results of the power spectrum calculations were compared. The measurements were performed in the mixing vessel with flat bottom. The vessel was equipped with four baffles and agitated with a six-blade pitched blade impeller. Three values of the impeller speed (Reynolds number were tested. Long time series of the axial velocity component were measured in selected points. In each point the time series were analyzed and evaluated in a form of power spectrum.
LDA measurements and turbulence spectral analysis in an agitated vessel
Kysela, Bohuš; Konfršt, Jiří; Chára, Zdeněk
2013-04-01
During the last years considerable improvement of the derivation of turbulence power spectrum from Laser Doppler Anemometry (LDA) has been achieved. The irregularly sampled LDA data is proposed to approximate by several methods e.g. Lomb-Scargle method, which estimates amplitude and phase of spectral lines from missing data, methods based on the reconstruction of the auto-correlation function (referred to as correlation slotting technique), methods based on the reconstruction of the time series using interpolation between the uneven sampling and subsequent resampling etc. These different methods were used on the LDA data measured in an agitated vessel and the results of the power spectrum calculations were compared. The measurements were performed in the mixing vessel with flat bottom. The vessel was equipped with four baffles and agitated with a six-blade pitched blade impeller. Three values of the impeller speed (Reynolds number) were tested. Long time series of the axial velocity component were measured in selected points. In each point the time series were analyzed and evaluated in a form of power spectrum.
Thermodynamic analysis of cascade microcryocoolers with low pressure ratios
Radebaugh, Ray [National Institute of Standards and Technology, Boulder, Colorado 80305 (United States)
2014-01-29
The vapor-compression cycle for refrigeration near ambient temperature achieves high efficiency because the isenthalpic expansion of the condensed liquid is a rather efficient process. However, temperatures are limited to about 200 K with a single-stage system. Temperatures down to 77 K are possible with many stages. In the case of microcryocoolers using microcompressors, pressure ratios are usually limited to about 6 or less. As a result, even more stages are required to reach 77 K. If the microcompressors can be fabricated with low-cost wafer-level techniques, then the use of many stages with separate compressors may become a viable option for achieving temperatures of 77 K with high efficiency. We analyze the ideal thermodynamic efficiency of a cascade Joule-Thomson system for various temperatures down to 77 K and with low pressure ratios. About nine stages are required for 77 K, but fewer stages are also analyzed for operation at higher temperatures. For 77 K, an ideal second-law efficiency of 83 % of Carnot is possible with perfect recuperative heat exchangers and 65 % of Carnot is possible with no recuperative heat exchangers. The results are compared with calculated efficiencies in mixed-refrigerant cryocoolers over the range of 77 K to 200 K. Refrigeration at intermediate temperatures is also available. The use of single-component fluids in each of the stages is expected to eliminate the problem of pulsating flow and temperature oscillations experienced in microcryocoolers using mixed refrigerants.
Negative Control Outcomes and the Analysis of Standardized Mortality Ratios.
Richardson, David B; Keil, Alexander P; Tchetgen Tchetgen, Eric; Cooper, Glinda
2015-09-01
In occupational cohort mortality studies, epidemiologists often compare the observed number of deaths in the cohort to the expected number obtained by multiplying person-time accrued in the study cohort by the mortality rate in an external reference population. Interpretation of the result may be difficult due to noncomparability of the occupational cohort and reference population with respect to unmeasured risk factors for the outcome of interest. We describe an approach to estimate an adjusted standardized mortality ratio (aSMR) to control for such bias. The approach draws on methods developed for the use of negative control outcomes. Conditions necessary for unbiased estimation are described, as well as looser conditions necessary for bias reduction. The approach is illustrated using data on bladder cancer mortality among male Oak Ridge National Laboratory workers. The SMR for bladder cancer was elevated among hourly-paid males (SMR = 1.9; 95% confidence interval [CI] = 1.3, 2.7) but not among monthly-paid males (SMR = 1.0; 95% CI = 0.67, 1.3). After indirect adjustment using the proposed approach, the mortality ratios were similar in magnitude among hourly- and monthly-paid men (aSMR = 2.2; 95% CI = 1.5, 3.2; and, aSMR = 2.0; 95% CI = 1.4, 2.8, respectively). The proposed adjusted SMR offers a complement to typical SMR analyses.
Functional Spectral Analysis of Paleoclimatic Evolution in Lanzhou Area over the Last 15 ka
杨桂芳; 殷鸿福; 李长安; 陈中原
2003-01-01
In this paper,we make use of the functional spectral analysis to infer the periodicity of paleoclimate in the Hongzuisi section since about 15 ka. Through combined analysis of organic carbon isotope and CaCO3 content,the law of paleoclimatic evolution of the Hongzuisi section is obtained. There were climatic changes from 10 ka to about 0.1 ka over the last 15 ka. Among these cycles,the cycle of several ka is most remarkable. The result indicates that functional spectral analysis is helpful for paleoclimatic study,which can provide useful information about paleoclimatic reconstruction and future forecast.
VIBRATIONS DETECTION IN INDUSTRIAL PUMPS BASED ON SPECTRAL ANALYSIS TO INCREASE THEIR EFFICIENCY
Belhadef RACHID
2016-01-01
Full Text Available Spectral analysis is the key tool for the study of vibration signals in rotating machinery. In this work, the vibration analy-sis applied for conditional preventive maintenance of such machines is proposed, as part of resolved problems related to vibration detection on the organs of these machines. The vibration signal of a centrifugal pump was treated to mount the benefits of the approach proposed. The obtained results present the signal estimation of a pump vibration using Fourier transform technique compared by the spectral analysis methods based on Prony approach.
Li, Xiaoyan; Shin, Henry; Zhou, Ping; Niu, Xun; Liu, Jie; Rymer, William Zev
2014-05-01
The objective of this study was to help assess complex neural and muscular changes induced by stroke using power spectral analysis of surface electromyogram (EMG) signals. Fourteen stroke subjects participated in the study. They were instructed to perform isometric voluntary contractions by abducting the index finger. Surface EMG signals were collected from the paretic and contralateral first dorsal interosseous (FDI) muscles with forces ranging from 30% to 70% maximum voluntary contraction (MVC) of the paretic muscle. Power spectral analysis was performed to characterize features of the surface EMG in paretic and contralateral muscles at matched forces. A Linear Mixed Model was applied to identify the spectral changes in the hemiparetic muscle and to examine the relation between spectral parameters and contraction levels. Regression analysis was performed to examine the correlations between spectral characteristics and clinical features. Differences in power spectrum distribution patterns were observed in paretic muscles when compared with their contralateral pairs. Nine subjects showed increased mean power frequency (MPF) in the contralateral side (>15 Hz). No evident spectrum difference was observed in 3 subjects. Only 2 subjects had higher MPF in the paretic muscle than the contralateral muscle. Pooling all subjects' data, there was a significant reduction of MPF in the paretic muscle compared with the contralateral muscle (paretic: 168.7 ± 7.6 Hz, contralateral: 186.1 ± 8.7 Hz, mean ± standard error, F=36.56, ppower spectrum did not confirm a significant correlation between the MPF and contraction force in either hand (F=0.7, p>0.5). There was no correlation between spectrum difference and Fugl-Meyer or Chedoke scores, or ratio of paretic and contralateral MVC (p>0.2). There appears to be complex muscular and neural processes at work post stroke that may impact the surface EMG power spectrum. The majority of the tested stroke subjects had lower MPF in the
Olsson, Per-Ivar; Dahlin, Torleif; Fiandaca, Gianluca; Auken, Esben
2015-12-01
Combined resistivity and time-domain direct current induced polarization (DCIP) measurements are traditionally carried out with a 50% duty cycle current waveform, taking the resistivity measurements during the on-time and the IP measurements during the off-time. One drawback with this method is that only half of the acquisition time is available for resistivity and IP measurements, respectively. In this paper, this limitation is solved by using a current injection with 100% duty cycle and also taking the IP measurements in the on-time. With numerical modelling of current waveforms with 50% and 100% duty cycles we show that the waveforms have comparable sensitivity for the spectral Cole-Cole parameters and that signal level is increased up to a factor of 2 if the 100% duty cycle waveform is used. The inversion of field data acquired with both waveforms confirms the modelling results and shows that it is possible to retrieve similar inversion models with either of the waveforms when inverting for the spectral Cole-Cole parameters with the waveform of the injected current included in the forward computations. Consequently, our results show that on-time measurements of IP can reduce the acquisition time by up to 50% and increase the signal-to-noise ratio by up to 100% almost without information loss. Our findings can contribute and have a large impact for DCIP surveys in general and especially for surveys where time and reliable data quality are important factors. Specifically, the findings are of value for DCIP surveys conducted in urban areas where anthropogenic noise is an issue and the heterogeneous subsurface demands time-consuming 3D acquisitions.
Yamamoto, H.; Mizutani, K.; Saito, T. [Iwate University, Iwate (Japan). Faculty of Engineering
1996-05-01
The peak period of the horizontal/vertical spectral ratio of microtremors was referred to the underground structure for the purpose of finding out if it was possible to estimate the ground structure by use of the peak period of the spectral ratio. The observation was carried in the areas of Morioka City and Hachinohe City using seismographs for measuring east-west, north-south, and up-down motions. As for the relationship between the peak period of the spectral ratio distribution involving 490 observation sites and the known gravity anomalies in the Morioka City area, it was found that the peak period of the spectral ratio tended to be shorter from west toward east while the gravity anomalies were greater from west toward east. Again, as for the relations with the underground geology, the period was longer when the distance to the granite basement was greater, and shorter when smaller. In the Hachinohe City area, relations not only of the first period peak but also of the second period peak to the basement were disclosed, which indicates the possibility that the peak period of the spectral ratio will be used as a means for estimating the basement structure. 2 refs., 8 figs.
Yamamoto, H.; Mizutani, K.; Saito, T. [Iwate University, Iwate (Japan). Faculty of Engineering
1996-05-01
The peak period of the horizontal/vertical spectral ratio of microtremors was referred to the underground structure for the purpose of finding out if it was possible to estimate the ground structure by use of the peak period of the spectral ratio. The observation was carried in the areas of Morioka City and Hachinohe City using seismographs for measuring east-west, north-south, and up-down motions. As for the relationship between the peak period of the spectral ratio distribution involving 490 observation sites and the known gravity anomalies in the Morioka City area, it was found that the peak period of the spectral ratio tended to be shorter from west toward east while the gravity anomalies were greater from west toward east. Again, as for the relations with the underground geology, the period was longer when the distance to the granite basement was greater, and shorter when smaller. In the Hachinohe City area, relations not only of the first period peak but also of the second period peak to the basement were disclosed, which indicates the possibility that the peak period of the spectral ratio will be used as a means for estimating the basement structure. 2 refs., 8 figs.
Jirkovská, A; Boucek, P; Pumprla, J; Hosová, J; Skibová, J; Wosková, V
1999-07-01
The objective of the work was to evaluate the contribution of examining autonomic neuropathy in diabetic patients to early diagnosis of Charcot's osteoarthropathy by classical Ewing's tests, as well as the more recent method--spectral analysis of heart rate variability. The authors examined 18 diabetic patients in the early stage of Charcot's osteoarthropathy and the results were compared with a group of 30 subjects matched for age and sex. The results of examination by Ewing's test (heart rate variability during deep breathing, in orthostasis and during Valsalva's manoeuvre and blood pressure changes during orthostasis) revealed autonomic neuropathy in all examined patients, in one subject incipient neuropathy and in 17 of 18 patients manifest or severe neuropathy. The patients differed from controls highly significantly in all parameters of Ewing's tests with the exception of parameter 30:15 in orthostasis. The greatest sensitivity was recorded in the examination of the I-E difference during deep respiration. RRmax/RRmin and the brake index in orthostasis and Valsalva's ratio. The lowest sensitivity was recorded in the examination of the orthostatic fall of blood pressure. On spectral analysis the patients differed highly significantly from controls in all investigated parameters, the highest discriminating value was found in parameters of the total spectral power in the standing position (2) and the power in the low-frequency area in position 2, the first parameter alone was correctly discriminated in 94%. Examination of autonomic neuropathy significantly improves the diagnosis of Charcot's osteoarthropathy. In addition to the classical Ewing tests spectral analysis of heart rate variability proved also a suitable method for its evaluation.
Kim, Duho; Jansen, Rolf A.; Windhorst, Rogier A.
2016-01-01
We analyze the intrinsic flux ratios of simple and composite stellar populations for various visible--near-infrared filters with respect to ˜3.5μm (L-band), and their dependence on metallicity, star-formation history, and effective mean age. This study is motivated by the fact that light from galaxies is reddened and attenuated by dust via scattering and absorption, where different sightlines across the face of a galaxy suffer various amounts of extinction. Ignoring the effects of this extinction could lead one to infer lower stellar mass, and SFR, or higher metallicity. Tamura et al. (2009) developed an approximate method, dubbed the "βV" method, which corrects for dust-extinction on a pixel-by-pixel basis, by comparing the observed flux ratio and empirical estimate of the intrinsic flux ratio of optical and ˜3.5μm broadband data. Here, we aim to validate and test the limits of the βV method for various filters spanning the visible through near-infrared wavelength range. Through extensive modeling, we test their assumptions for the intrinsic flux ratios for a wide variety of simple and composite stellar populations. We build spectral energy distributions (SEDs) of simple stellar populations (SSPs), by adopting Starburst99 and BC03 models for young (100Myr) stellar populations, respectively, and linear combinations of these for intermediate ages. We then construct composite stellar population (CSP) SEDs by combining SSP SEDs for various realistic star-formation histories (SFHs). We convolve filter response curves of visible--near-infrared filters for HST imaging surveys and mid-infrared filters in current (WISE, Spitzer/IRAC) and near-future use (JWST/NIRCam) with each model SED, to obtain intrinsic flux ratios (βλ,0). We find that βNIR,0 is only varying slightly as a function of metallicity but is insensitive to SFH or redshift (z≤2). We also find a narrow range of βV,0 (0.7+0.05-0.08) for early Hubble type galaxies (E and S0) using SEDs of randomly
Spectral characterization as a tool for parchment analysis
Radis, Michela; Iacomussi, Paola; Rossi, Giuseppe
2015-06-01
The paper presents an investigation on the correlation between spectral characteristics and conservation conditions of parchment to define a NON invasive methodology able to detect and monitor deterioration process in historical parchment without the need of taking small samples. To verify the feasibility and define the most appropriate measurement method, several samples of contemporary parchments, produced following ancient recipes and coming from different animal species, with different degrees of artificially induced damage, were analyzed. The SRF and STF of each sample were measured in the same point, before and after each step of the artificial ageing treatment. Having at disposal a parchment coming from a whole lamb leather, allowed also the study of the correlations between the variations of SRF - STF and the intrinsic factors of a parchment like the variability of animal skin anatomy and of manufacturing. Analyzing different samples allowed also the definition of the measuring method sensitivity and of reference spectrum for the different animal species parchments with accuracy limits. The definition of a reference spectrum of not damaged parchment with acceptability limits is a necessary step for understanding, through SRF - STF measurements, historical parchments conservation conditions: indeed it is necessary to know if deviations from the reference spectrum are ascribable to damage or only to parchment anatomic/production variability. As a case study, the method has been applied to two historical parchment scrolls stored at the Archivio di Stato di Torino (Italy). The SRF - STF of both scrolls was acquired in several points of the scroll, the average spectrum of each scroll was compared with the reference spectra with the relative tolerance limits, recognizing the animal species and damage alterations and demonstrating the feasibility of the method.
Spectral Estimation Methods Comparison and Performance Analysis on a Steganalysis Application
Mataracioglu, Tolga
2011-01-01
Steganography is the art and science of writing hidden messages in such a way that no one apart from the intended recipient knows of the existence of the message. In today's world, it is widely used in order to secure the information. In this paper, the traditional spectral estimation methods are introduced. The performance analysis of each method is examined by comparing all of the spectral estimation methods. Finally, from utilizing those performance analyses, a brief pros and cons of the spectral estimation methods are given. Also we give a steganography demo by hiding information into a sound signal and manage to pull out the information (i.e, the true frequency of the information signal) from the sound by means of the spectral estimation methods.
Spectral analysis of time series of categorical variables in earth sciences
Pardo-Igúzquiza, Eulogio; Rodríguez-Tovar, Francisco J.; Dorador, Javier
2016-10-01
Time series of categorical variables often appear in Earth Science disciplines and there is considerable interest in studying their cyclic behavior. This is true, for example, when the type of facies, petrofabric features, ichnofabrics, fossil assemblages or mineral compositions are measured continuously over a core or throughout a stratigraphic succession. Here we deal with the problem of applying spectral analysis to such sequences. A full indicator approach is proposed to complement the spectral envelope often used in other disciplines. Additionally, a stand-alone computer program is provided for calculating the spectral envelope, in this case implementing the permutation test to assess the statistical significance of the spectral peaks. We studied simulated sequences as well as real data in order to illustrate the methodology.
X-ray spectral and temporal analysis of Narrow Line Seyfert 1 galaxy Was 61
Dou, Liming; Ai, Yanli; Yuan, Weimin; Zhou, Hongyan; Dong, Xiao-Bo
2016-01-01
We present an analysis of spectrum and variability of the bright reddened narrow line Seyfert 1 galaxy Was~61 using 90 ks archival {\\it XMM-Newton} data. The X-ray spectrum in 0.2-10 keV can be characterized by an absorbed power-law plus soft excess and an Fe K$\\alpha$ emission line. The power-law spectral index remains constant during the flux variation. The absorbing material is mildly ionized, with a column density of 3.2$\\times$10$^{21}$ cm$^{-2}$, and does not appear to vary during the period of the X-ray observation. If the same material causes the optical reddening (E(B-V)$\\simeq$0.6 mag), it must be located outside the narrow line region with a dust-to-gas ratio similar to the average Galactic value. We detect significant variations of the Fe K$\\alpha$ line during the observational period. A broad Fe K$\\alpha$ line at $\\simeq$6.7 keV with a width of $\\sim$0.6 keV is detected in the low flux segment of the first 40 ks exposure, and is absent in the spectra of other segments; a narrow Fe K$\\alpha$ emiss...
Automics: an integrated platform for NMR-based metabonomics spectral processing and data analysis
Qu Lijia
2009-03-01
Full Text Available Abstract Background Spectral processing and post-experimental data analysis are the major tasks in NMR-based metabonomics studies. While there are commercial and free licensed software tools available to assist these tasks, researchers usually have to use multiple software packages for their studies because software packages generally focus on specific tasks. It would be beneficial to have a highly integrated platform, in which these tasks can be completed within one package. Moreover, with open source architecture, newly proposed algorithms or methods for spectral processing and data analysis can be implemented much more easily and accessed freely by the public. Results In this paper, we report an open source software tool, Automics, which is specifically designed for NMR-based metabonomics studies. Automics is a highly integrated platform that provides functions covering almost all the stages of NMR-based metabonomics studies. Automics provides high throughput automatic modules with most recently proposed algorithms and powerful manual modules for 1D NMR spectral processing. In addition to spectral processing functions, powerful features for data organization, data pre-processing, and data analysis have been implemented. Nine statistical methods can be applied to analyses including: feature selection (Fisher's criterion, data reduction (PCA, LDA, ULDA, unsupervised clustering (K-Mean and supervised regression and classification (PLS/PLS-DA, KNN, SIMCA, SVM. Moreover, Automics has a user-friendly graphical interface for visualizing NMR spectra and data analysis results. The functional ability of Automics is demonstrated with an analysis of a type 2 diabetes metabolic profile. Conclusion Automics facilitates high throughput 1D NMR spectral processing and high dimensional data analysis for NMR-based metabonomics applications. Using Automics, users can complete spectral processing and data analysis within one software package in most cases
Guzman, Marco; Lanas, Andres; Olavarria, Christian; Azocar, Maria Josefina; Muñoz, Daniel; Madrid, Sofia; Monsalve, Sebastian; Martinez, Francisca; Vargas, Sindy; Cortez, Pedro; Mayerhoff, Ross M
2015-01-01
The present study aimed to assess three different singing styles (pop, rock, and jazz) with laryngoscopic, acoustic, and perceptual analysis in healthy singers at different loudness levels. Special emphasis was given to the degree of anterior-posterior (A-P) laryngeal compression, medial laryngeal compression, vertical laryngeal position (VLP), and pharyngeal compression. Prospective study. Twelve female trained singers with at least 5 years of voice training and absence of any voice pathology were included. Flexible and rigid laryngeal endoscopic examinations were performed. Voice recording was also carried out. Four blinded judges were asked to assess laryngoscopic and auditory perceptual variables using a visual analog scale. All laryngoscopic parameters showed significant differences for all singing styles. Rock showed the greatest degree for all of them. Overall A-P laryngeal compression scores demonstrated significantly higher values than overall medial compression and VLP. High loudness level produced the highest degree of A-P compression, medial compression, pharyngeal compression, and the lowest VLP for all singing styles. Additionally, rock demonstrated the highest values for alpha ratio (less steep spectral slope), L1-L0 ratio (more glottal adduction), and Leq (more vocal intensity). Statistically significant differences between the three loudness levels were also found for these acoustic parameters. Rock singing seems to be the style with the highest degree of both laryngeal and pharyngeal activity in healthy singers. Although, supraglottic activity during singing could be labeled as hyperfunctional vocal behavior, it may not necessarily be harmful, but a strategy to avoid vocal fold damage. Copyright © 2015 The Voice Foundation. Published by Elsevier Inc. All rights reserved.
Branchini, Lauren A; Adhi, Mehreen; Regatieri, Caio V; Nandakumar, Namrata; Liu, Jonathan J; Laver, Nora; Fujimoto, James G; Duker, Jay S
2013-01-01
Objective To analyze the morphology and vasculature of the choroid in healthy eyes using spectral-domain optical coherence tomography (SD-OCT). Design Cross-sectional retrospective review. Participants Forty-two healthy subjects (42 eyes), with no ocular disease who underwent high-definition scanning with Cirrus HD-OCT at the New England Eye Center, Boston, Massachusetts between November 2009 and September 2010. Methods The SD-OCT images were evaluated for morphological features of the choroid, including the shape of the choroid-scleral border, location of the thickest point of choroid and regions of focal choroidal thinning. Total choroidal thickness and large choroidal vessel layer thickness were measured by two independent observers experienced in analyzing OCT images using the Cirrus linear measurement tool at the fovea, 750μm nasal and temporal to the fovea. Custom software was used to calculate the ratio of choroidal stroma to the choroidal vessel lumen. Main Outcome Measures Qualitative assessment of the choroidal morphology, quantitative analysis of choroidal vasculature and use of a novel automated software to determine the ratio of choroidal stromal area to the area of choroidal vessel lumen. Results The 42 subjects had a mean age of 51.6 years. All subjects (100%) had a “bowl” or convex shape to the choroid-sclera junction and the thickest point of the choroid was under the fovea in 88.0% of the subjects. The mean choroidal thickness was 256.8±75.8μm, thickness of the large choroidal vessel layer was 204.3±65.9μm and that of medium choroidal vessel layer/choriocapillaris layer was 52.9±20.6μm beneath the fovea. The ratio of large choroidal vessel layer thickness to the total choroidal thickness beneath the fovea was 0.7±0.06. The software generated ratio of choroidal stromal area to the choroidal vessel lumen area to be 0.27±0.08, suggesting that choroidal vessel lumen forms a greater proportion of the choroid than choroidal stroma in
V P S Naidu; M R S Reddy
2003-12-01
Frequency domain representation of a short-term heart-rate time series (HRTS) signal is a popular method for evaluating the cardiovascular control system. The spectral parameters, viz. percentage power in low frequency band (%PLF), percentage power in high frequency band (%PHF), power ratio of low frequency to high frequency (PRLH), peak power ratio of low frequency to high frequency (PPRLH) and total power (TP) are extrapolated from the averaged power spectrum of twenty-ﬁve healthy subjects, and 16 acute anterior-wall and nine acute inferior-wall myocardial infarction (MI) patients. It is observed that parasympathetic activity predominates in healthy subjects. From this observation we conclude that during acute myocardial infarction, the anterior wall MI has stimulated sympathetic activity, while the acute inferior wall MI has stimulated parasympathetic activity. Results obtained from ARMA-based analysis of heart-rate time series signals are capable of complementing the clinical examination results.
Signal Classification in Fading Channels Using Cyclic Spectral Analysis
Eric Like
2009-01-01
Full Text Available Cognitive Radio (CR, a hierarchical Dynamic Spectrum Access (DSA model, has been considered as a strong candidate for future communication systems improving spectrum efficiency utilizing unused spectrum of opportunity. However, to ensure the effectiveness of dynamic spectrum access, accurate signal classification in fading channels at low signal to noise ratio is essential. In this paper, a hierarchical cyclostationary-based classifier is proposed to reliably identify the signal type of a wide range of unknown signals. The proposed system assumes no a priori knowledge of critical signal statistics such as carrier frequency, carrier phase, or symbol rate. The system is designed with a multistage approach to minimize the number of samples required to make a classification decision while simultaneously ensuring the greatest reliability in the current and previous stages. The system performance is demonstrated in a variety of multipath fading channels, where several multiantenna-based combining schemes are implemented to exploit spatial diversity.
IR spectral analysis for the diagnostics of crust earthquake precursors
Umarkhodgaev, R. M.; Liperovsky, V. A.; Mikhailin, V. V.; Meister, C.-V.; Naumov, D. Ju
2012-04-01
In regions of future earthquakes, a few days before the seismic shock, the emanation of radon and hydrogen is being observed, which causes clouds of increased ionisation in the atmosphere. In the present work the possible diagnostics of these clouds using infrared (IR) spectroscopy is considered, which may be important and useful for the general geophysical system of earthquake prediction and the observation of industrial emissions of radioactive materials into the atmosphere. Some possible physical processes are analysed, which cause, under the condition of additional ionisation in a pre-breakdown electrical field, emissions in the IR interval. In doing so, the transparency region of the IR spectrum at wavelengths of 7-15 μm is taken into account. This transparency region corresponds to spectral lines of small atmospheric constituents like CH4, CO2, N2O, NO2, NO, and O3. The possible intensities of the IR emissions observable in laboratories and in nature are estimated. The acceleration process of the electrons in the pre-breakdown electrical field before its adhesion to the molecules is analysed. The laboratory equipment for the investigation of the IR absorption spectrum is constructed for the cases of normal and decreased atmospheric pressures. The syntheses of ozone and nitrous oxides are performed in the barrier discharge. It is studied if the products of the syntheses may be used to model atmospheric processes where these components take part. Spectra of products of the syntheses in the wavelength region of 2-10 μm are observed and analysed. A device is created for the syntheses and accumulation of nitrous oxides. Experiments to observe the IR-spectra of ozone and nitrous oxides during the syntheses and during the further evolution of these molecules are performed. For the earthquake prediction, practically, the investigation of emission spectra is most important, but during the laboratory experiments, the radiation of the excited molecules is shifted by a
Meng, Xiaoyan; Ni, Cheng; Shen, Yaqi; Hu, Xuemei; Chen, Xiao; Li, Zhen; Hu, Daoyu
2017-01-01
Abstract To investigate the value of quantitative analysis in dual energy spectral computed tomography (DESCT) for differentiating malignant gastric mucosal lesions from benign gastric mucosal lesions (including gastric inflammation [GI] and normal gastric mucosa [NGM]). This study was approved by the ethics committee, and all patients provided written informed consent. A total of 161 consecutive patients (63 with gastric cancer [GC], 48 with GI, and 50 with NGM) who underwent dual-phase contrast enhanced DESCT scans in the arterial phase (AP) and portal venous phase (PVP) were included in this study. Iodine concentration (IC) in lesions was derived from the iodine-based material-decomposition images and normalized to that in the aorta to obtain normalized IC (nIC). The ratios of IC and nIC between the AP and PVP were calculated. Diagnostic confidence for GC and GI was evaluated with reviewing the features including gastric wall thickness, focal, and eccentric on the conventional polychromatic images. All statistical analyses were performed by using statistical software SPSS 17.0 (SPSS, Chicago, IL). IC and nIC in GC differed significantly from those in GI and NGM, except for nICAP in comparing GC with GI. Mean nIC values of GC (0.18 ± 0.06 in AP and 0.62 ± 0.16 in PVP) were significantly higher than that of NGM (0.12 ± 0.03 in AP and 0.37 ± 0.08 in PVP) (all P nIC and IC in PVP had high sensitivities of 88.89% and 90.48%, respectively, in differentiating GC from NGM, while the sensitivities were 71.43% and 88.89% during AP. Ratios IC and nIC ratios did not provide adequate diagnostic accuracy with their area under curves less than 0.65. With the conventional features, the diagnostic accuracies for GC and GI were 75.0% and 98.0%, respectively. Quantitative analysis of DESCT imaging parameters for gastric mucosa, such as nIC and IC, is useful for differentiating malignant from benign gastric mucosal lesions. PMID:28079827
Analysis of the Structure Ratios of the Funding Sources
Maria Daniela Bondoc
2014-06-01
Full Text Available The funding sources of the assets and liabilities in the balance sheet include equity capitals and the debts of the entity. The analysis of the structure rates of the funding sources allows for making assessments related to the funding policy, highlighting the financial autonomy and how resources are provided. Using the literature specializing in economic and financial analysis, this paper aims at presenting these rates that focus, on the one hand, to reflect the degree of financial dependence (the rate of financial stability, the rate of global financial autonomy, the rate of on-term financial autonomy and on the other hand the debt structure (the rate of short-term debts, the global indebtedness rate, the on-term indebtedness rate. Based on the financial statements of an entity in the Argeş County, I analysed these indicators, and I drew conclusions and made assessments related to the autonomy, indebtedness and financial stability of the studied entity.
Using Stable Isotope Ratio Analysis to Distinguish Perchlorate Sources
2011-03-30
Death Valley caliche West Texas OCl - + O 3 ClO 2 + O 3 -5.0 0.0 5.0 10 15 20 -30 -20 -10 0 10 20 30 40 50 1 7 O ( p e r m i l ) 18O (per mil...Synthetic solids Atacama caliche/ fertilizer Death Valley caliche West Texas OCl - + UV ClO 2 + UV Perchlorate generated with UV 36Cl Analysis Long
Multi spectral imaging analysis for meat spoilage discrimination
Christiansen, Asger Nyman; Carstensen, Jens Michael; Papadopoulou, Olga
) was performed in parallel with videometer image snapshots and sensory analysis. Odour and colour characteristics of meat were determined by a test panel and attributed into three pre-characterized quality classes, namely Fresh; Semi Fresh and Spoiled during the days of its shelf life. So far, different...... classification methods: Naive Bayes Classifier as a reference model, Canonical Discriminant Analysis (CDA) and Support Vector Classification (SVC). As the final step, generalization of the models was performed using k-fold validation (k=10). Results showed that image analysis provided good discrimination of meat...... samples regarding the spoilage process as evaluated from sensory as well as from microbiological data. The support vector classification (SVC) model outperformed other models. Specifically, the misclassification error rate (MER), derived from odour characteristics, was 18% for both aerobic and MAP meat...
Proskurin, S G; Avsievich, T I
2014-01-01
In this study the experimental dependencies of the velocity of shuttle endoplasmic motion in the isolated plasmodial strand of Physarum polycephalum obtained by laser Doppler microscopy are presented. The spectral analysis of the time dependencies of the endoplasm allows obtaining two distinct harmonic components. Influence of KCN and SHAM--inhibitors of cellular respiration--leads to a complete cessation of endoplasmic motion in the strand. After removal of the inhibitors the respiratory system becomes normal, gradually restoring the activity of both harmonic oscillation sources. Based on the spectral analysis the simulated time-dependent velocity of the endoplasmic motion is rather good consistent with experimental data.
Michel, Clotaire; Hobiger, Manuel; Edwards, Benjamin; Poggi, Valerio; Burjanek, Jan; Cauzzi, Carlo; Kästli, Philipp; Fäh, Donat
2016-04-01
The Swiss Seismological Service operates one of the densest national seismic networks in the world, still rapidly expanding (see http://www.seismo.ethz.ch/monitor/index_EN). Since 2009, every newly instrumented site is characterized following an established procedure to derive realistic 1D VS velocity profiles. In addition, empirical Fourier spectral modeling is performed on the whole network for each recorded event with sufficient signal-to-noise ratio. Besides the source characteristics of the earthquakes, statistical real time analyses of the residuals of the spectral modeling provide a seamlessly updated amplification function w.r. to Swiss rock conditions at every station. Our site characterization procedure is mainly based on the analysis of surface waves from passive experiments and includes cross-checks of the derived amplification functions with those obtained through spectral modeling. The systematic use of three component surface-wave analysis, allowing the derivation of both Rayleigh and Love waves dispersion curves, also contributes to the improved quality of the retrieved profiles. The results of site characterisation activities at recently installed strong-motion stations depict the large variety of possible effects of surface geology on ground motion in the Alpine context. Such effects range from de-amplification at hard-rock sites to amplification up to a factor of 15 in lacustrine sediments with respect to the Swiss reference rock velocity model. The derived velocity profiles are shown to reproduce observed amplification functions from empirical spectral modeling. Although many sites are found to exhibit 1D behavior, our procedure allows the detection and qualification of 2D and 3D effects. All data collected during the site characterization procedures in the last 20 years are gathered in a database, implementing a data model proposed for community use at the European scale through NERA and EPOS (www.epos-eu.org). A web stationbook derived from it
Financial and Staffing Ratio Analysis: Predicting Fiscal Distress in School Districts.
Lee, Robert Alan
1983-01-01
From analysis of data from 579 school districts it is concluded that financial ratios have the ability to forecast fiscal distress a year in advance. Liquidity ratios and salary and fringe benefit ratios were found to be strong forecasters, while per pupil expenditure data had little predictive value. (MJL)
EEG Signal Decomposition and Improved Spectral Analysis Using Wavelet Transform
2001-10-25
research and medical applications. Wavelet transform (WT) is a new multi-resolution time-frequency analysis method. WT possesses localization feature both... wavelet transform , the EEG signals are successfully decomposed and denoised. In this paper we also use a ’quasi-detrending’ method for classification of EEG
Sleep EEG spectral analysis in a diurnal rodent : Eutamias sibiricus
DIJK, DJ; DAAN, S
1989-01-01
1. Sleep was studied in the diurnal rodent Eutamias sibiricus, chronically implanted with EEG and EMG electrodes. Analysis of the distribution of wakefulness, nonrapid eye movement (NREM) sleep, and rapid eye movement (REM) sleep over the 24 h period (LD 12:12) showed that total sleep time was 27.5%
de Beer, N A M; Andriessen, P; Berendsen, R C M; Oei, S G; Wijn, P F F; Oetomo, S Bambang
2004-12-01
A customized filtering technique is introduced and compared with fast Fourier transformation (FFT) for analyzing heart rate variability (HRV) in neonates from short-term recordings. FFT is classically the most commonly used spectral technique to investigate cardiovascular fluctuations. FFT requires stability of the physiological signal within a 300 s time window that is usually analyzed in adults. Preterm infants, however, show characteristics of rapidly fluctuating heart rate and blood pressure due to an immature autonomic regulation, resulting in non-stationarity of these signals. Therefore neonatal studies use (half-overlapping or moving) windows of 64 s length within a recording time of 2-5 min. The proposed filtering technique performs a filtering operation in the frequency range of interest before calculating the spectrum, which allows it to perform an analysis of shorter periods of only 42 s. The frequency bands of interest are 0.04-0.15 Hz (low frequency, LF) and 0.4-1.5 Hz (high frequency, HF). Although conventional FFT analysis as well as the proposed alternative technique result in errors in the estimation of LF power, due to spectral leakage from the very low frequencies, FFT analysis is more sensitive to this effect. The response times show comparable behavior for both the techniques. Applying both the methods to heart rate data obtained from a neonate before and after atropine administration (inducing a wide range of HRV), shows a very significant correlation between the two methods in estimating LF and HF power. We conclude that a customized filtering technique might be beneficial for analyzing HRV in neonates because it reduces the necessary time window for signal stability.
Mapping tropical dry forest succession using multiple criteria spectral mixture analysis
Cao, Sen; Yu, Qiuyan; Sanchez-Azofeifa, Arturo; Feng, Jilu; Rivard, Benoit; Gu, Zhujun
2015-11-01
Tropical dry forests (TDFs) in the Americas are considered the first frontier of economic development with less than 1% of their total original coverage under protection. Accordingly, accurate estimates of their spatial extent, fragmentation, and degree of regeneration are critical in evaluating the success of current conservation policies. This study focused on a well-protected secondary TDF in Santa Rosa National Park (SRNP) Environmental Monitoring Super Site, Guanacaste, Costa Rica. We used spectral signature analysis of TDF ecosystem succession (early, intermediate, and late successional stages), and its intrinsic variability, to propose a new multiple criteria spectral mixture analysis (MCSMA) method on the shortwave infrared (SWIR) of HyMap image. Unlike most existing iterative mixture analysis (IMA) techniques, MCSMA tries to extract and make use of representative endmembers with spectral and spatial information. MCSMA then considers three criteria that influence the comparative importance of different endmember combinations (endmember models): root mean square error (RMSE); spatial distance (SD); and fraction consistency (FC), to create an evaluation framework to select a best-fit model. The spectral analysis demonstrated that TDFs have a high spectral variability as a result of biomass variability. By adopting two search strategies, the unmixing results showed that our new MCSMA approach had a better performance in root mean square error (early: 0.160/0.159; intermediate: 0.322/0.321; and late: 0.239/0.235); mean absolute error (early: 0.132/0.128; intermediate: 0.254/0.251; and late: 0.191/0.188); and systematic error (early: 0.045/0.055; intermediate: -0.211/-0.214; and late: 0.161/0.160), compared to the multiple endmember spectral mixture analysis (MESMA). This study highlights the importance of SWIR in differentiating successional stages in TDFs. The proposed MCSMA provides a more flexible and generalized means for the best-fit model determination
Liu, Yan; Li, Yang
2014-07-01
To explore the differences of mixed-pixel in spectral mixing mechanism at micro-and macro -scale, the micro- simulation of snow-bare soil mixed pixel was taken as the object of study in an artificial test environment. Reflectance spectra of mixed pixel and snow, bare soil endmember with different area ratio were collected by full-band spectrometer with fixed probe distance. Qualitative and quantitative analysis of original reflectance spectra was done, and reflectance spectra form 350 to 2 500 nm and normalized reflectance spectral data of 350 to 1 815 nm excluding noise were normalized. At the same time, we collected EOS/MODIS and Environment and Disaster Monitoring Satellites data of the same period over the same area and analyzed the correlation of channels in visible, near-infrared and shortwave infrared wavelength range at different resolution scales and the relationship between spectrum of mixed snow-soil and endmember pixel in MODIS image was analyzed. The results showed that, (1) At the micro scale, non-linear relationship existed between mixed pixel and endmember within the scope of the full-wave and linear relationship existed in sub-band wavelength range; (2) At the macro scale, linear relationship existed between mixed pixel and endmember. (3) In statistics of spectral values, the correlation between snow-soil mixture and endmember is positive for snow-soil mixture and snow endmember, and is negative for snow-soil mixture and soil endmember.
Shen, Jie; Wang, Li-Lian
2011-01-01
Along with finite differences and finite elements, spectral methods are one of the three main methodologies for solving partial differential equations on computers. This book provides a detailed presentation of basic spectral algorithms, as well as a systematical presentation of basic convergence theory and error analysis for spectral methods. Readers of this book will be exposed to a unified framework for designing and analyzing spectral algorithms for a variety of problems, including in particular high-order differential equations and problems in unbounded domains. The book contains a large
An open source tool for heart rate variability spectral analysis.
Rodríguez-Liñares, L; Méndez, A J; Lado, M J; Olivieri, D N; Vila, X A; Gómez-Conde, I
2011-07-01
In this paper we describe a software package for developing heart rate variability analysis. This package, called RHRV, is a third party extension for the open source statistical environment R, and can be freely downloaded from the R-CRAN repository. We review the state of the art of software related to the analysis of heart rate variability (HRV). Based upon this review, we motivate the development of an open source software platform which can be used for developing new algorithms for studying HRV or for performing clinical experiments. In particular, we show how the RHRV package greatly simplifies and accelerates the work of the computer scientist or medical specialist in the HRV field. We illustrate the utility of our package with practical examples.
Graph spectral analysis of protein interaction network evolution
Thorne, Thomas; Stumpf, Michael P. H.
2012-01-01
We present an analysis of protein interaction network data via the comparison of models of network evolution to the observed data. We take a Bayesian approach and perform posterior density estimation using an approximate Bayesian computation with sequential Monte Carlo method. Our approach allows us to perform model selection over a selection of potential network growth models. The methodology we apply uses a distance defined in terms of graph spectra which captures the network data more natu...
Spectral analysis of optical emission of microplasma in sea water
Gamaleev, Vladislav; Morita, Hayato; Oh, Jun-Seok; Furuta, Hiroshi; Hatta, Akimitsu
2016-09-01
This work presents an analysis of optical emission spectra from microplasma in three types of liquid, namely artificial sea water composed of 10 typical agents (10ASW), reference solutions each containing a single agent (NaCl, MgCl2 + H2O, Na2SO4, CaCl2, KCl, NaHCO3, KBr, NaHCO3, H3BO3, SrCl2 + H2O, NaF) and naturally sampled deep sea water (DSW). Microplasma was operated using a needle(Pd)-to-plate(Pt) electrode system sunk into each liquid in a quartz cuvette. The radius of the tip of the needle was 50 μm and the gap between the electrodes was set at 20 μm. An inpulse generator circuit, consisting of a MOSFET switch, a capacitor, an inductor and the resistance of the liquid between the electrodes, was used as a pulse current source for operation of discharges. In the spectra, the emission peaks for the main components of sea water and contaminants from the electrodes were detected. Spectra for reference solutions were examined to enable the identification of unassigned peaks in the spectra for sea water. Analysis of the Stark broadening of H α peak was carried out to estimate the electron density of the plasma under various conditions. The characteristics of microplasma discharge in sea water and the analysis of the optical emission spectra will be presented. This work was supported by JSPS KAKENHI Grant Number 26600129.
Processing of spectral X-ray data with principal components analysis
Butler, A P H; Cook, N J; Butzer, J; Schleich, N; Tlustos, L; Scott, N; Grasset, R; de Ruiter, N; Anderson, N G
2011-01-01
The goal of the work was to develop a general method for processing spectral x-ray image data. Principle component analysis (PCA) is a well understood technique for multivariate data analysis and so was investigated. To assess this method, spectral (multi-energy) computed tomography (CT) data was obtained using a Medipix2 detector in a MARS-CT (Medipix All Resolution System). PCA was able to separate bone (calcium) from two elements with k-edges in the X-ray spectrum used (iodine and barium) within a mouse. This has potential clinical application in dual-energy CT systems and future Medipix3 based spectral imaging where up to eight energies can be recorded simultaneously with excellent energy resolution. (c) 2010 Elsevier B.V. All rights reserved.
Spectral Analysis of Blood Pressure Variability as a Quantitative Indicator of Driving Fatigue
李增勇; 焦昆; 陈铭; 王成焘
2004-01-01
The quantitative detector of driver fatigue presents appropriate warnings and helps to prevent traffic accidents.The aim of this study was to quantifiably evaluate driver mental fatigue using the power spectral analysis of the blood pressure variability (BPV) and subjective evaluation. In this experiment twenty healthy male subjects were required to perform a driving simulator task for 3-hours. The physiological variables for evaluating driver mental fatigue were spectral values of blood pressure variability (BPV)including very low frequency (VLF), low frequency (LF),high frequency (HF). As a result, LF, HF and LF/HF showed high correlations with driver mental fatigue but not found in VLF. The findings represent a possible utility of BPV spectral analysis in quantitatively evaluating driver mental fatigue.
Stochastic analysis of spectral broadening by a free turbulent shear layer
Hardin, J. C.; Preisser, J. S.
1981-01-01
The effect of the time-varying shear layer between a harmonic acoustic source and an observer on the frequency content of the observed sound is considered. Experimental data show that the spectral content of the acoustic signal is considerably broadened upon passing through such a shear layer. Theoretical analysis is presented which shows that such spectral broadening is entirely consistent with amplitude modulation of the acoustic signal by the time-varying shear layer. Thus, no actual frequency shift need be hypothesized to explain the spectral phenomenon. Experimental tests were conducted at 2, 4, and 6 kHz and at free jet flow velocities of 10, 20, and 30 m/s. Analysis of acoustic pressure time histories obtained from these tests confirms the above conclusion, at least for the low Mach numbers considered.
HCN hyperfine ratio analysis of massive molecular clumps
Schap, W. J.; Barnes, P. J.; Ordoñez, A.; Ginsburg, A.; Yonekura, Y.; Fukui, Y.
2017-03-01
We report a new analysis protocol for HCN hyperfine data, based on the PYSPECKIT package, and results of using this new protocol to analyse a sample area of seven massive molecular clumps from the Census of High- and Medium-mass Protostars (CHaMP) survey, in order to derive maps of column density for this species. There is a strong correlation between the HCN integrated intensity, IHCN, and previously reported I_HCO+ in the clumps, but I_N_{2H+} is not well correlated with either of these other two 'dense gas tracers'. The four fitted parameters from PYSPECKIT in this region fall in the range of VLSR = 8-10 km s-1, σV = 1.2-2.2 km s-1, Tex = 4-15 K, and τ = 0.2-2.5. These parameters allow us to derive a column density map of these clouds, without limiting assumptions about the excitation or opacity. A more traditional (linear) method of converting IHCN to total mass column gives much lower clump masses than our results based on the hyperfine analysis. This is primarily due to areas in the sample region of low I, low Tex, and high τ. We conclude that there may be more dense gas in these massive clumps not engaged in massive star formation than previously recognized. If this result holds for other clouds in the CHaMP sample, it would have dramatic consequences for the calibration of the Kennicutt-Schmidt star formation laws, including a large increase in the gas depletion time-scale in such regions.
Jonny Jonny
2016-05-01
Full Text Available This paper evaluated the financial performance of ABC hospital within the period of 2012 to 2013. To overcome the problems faced by the hospital related to how to measure and presented its financial performance in which financial ratio analysis was undertaken. These financial ratios were employed to measure the liquidity, assets utilization, long-term solvency and profitability of the hospital. This analysis was conducted in order to prove whether the hospital has been managed efficiently or not in accordance to Indonesian Hospital Quality Accreditation as stated in its clause on Administration Standard No. 5 Parameter No. 3 that the hospital financial management shall be conducted in appropriate way in order to guarantee its operation efficiently. The result showed that overall financial performance of ABC hospital increased considerably in those two years of the analysis. A significant change was occurred on its solvency ratio which was decreased from -2% to -8%, indicating its loose dependency due to its founder’s strong financial support. Therefore, based on this favorable result, the hospital was regarded to have efficient hospital management and thus, together with other standard fulfillment, it was accredited by Indonesian Health Ministry.
Asymptotic Spectral Analysis of Cross-Product Matrices.
1982-11-01
Ing ( +4. 1 o3) 8 , a-., .... , and ’E3 - 1Q(jzq) (4.4) a matriz partitioned so all Y2 subatrices are zero except for the multiples of Identity...from (4.7) (it gives them to be I (q-1 times). +S C 1-l2 uac P T (one)) be c, ba A Is within z71/ of A all the terms In the matriz In (4.6G) are of...Maar Barnes Building Fort Meade, MD 20755 1 495 Summer Street Boston , MA 02210 1 ATAA-SL, Library U.S. Army TRADOC Systems Commanding Officer Analysis
SPECTRAL ANALYSIS OF POLYMER MODIFIED BITUMEN USED IN WATERPROOFING
Maria RATAJCZAK
Full Text Available Asphalt is one of the most commonly used building material. The first attempts at modifying asphalt were made at the beginning of the twentieth century. Nowadays the most popular asphalt modifier is the styrene-butadiene-styrene (SBS. This thermoplastic elastomer increases the thermal resistance of bitumen, widens the range of plasticity and amends rheological properties. IR spectroscopy is by far the most common instrumental method used in analytical chemistry. The popularity of this method results from its simple measurement technique, universality and high precision. That is why IR spectroscopy applies to the analysis of polymer modified binder (PMB used in waterproofing.
Continental Spatio-temporal Data Analysis with Linear Spectral Mixture Model using FOSS
Kumar, U.; Nemani, R. R.; Ganguly, S.; Milesi, C.; Raja, K. S.; Wang, W.; Votava, P.; Michaelis, A.
2015-12-01
This work demonstrates the development and implementation of a Fully Constrained Least Squares (FCLS) unmixing model developed in C++ programming language with OpenCV package and boost C++ libraries in the NASA Earth Exchange (NEX). Visualization of the results is supported by GRASS GIS and statistical analysis is carried in R in a Linux system environment. FCLS was first tested on computer simulated data with Gaussian noise of various signal-to-noise ratio, and Landsat data of an agricultural scenario and an urban environment using a set of global endmembers of substrate (soils, sediments, rocks, and non-photosynthetic vegetation), vegetation that includes green photosynthetic plants and dark objects which encompasses absorptive substrate materials, clear water, deep shadows, etc. For the agricultural scenario, a spectrally diverse collection of 11 scenes of Level 1 terrain corrected, cloud free Landsat-5 TM data of Fresno, California, USA were unmixed and the results were validated with the corresponding ground data. To study an urbanized landscape, a clear sky Landsat-5 TM data were unmixed and validated with coincident World View-2 abundance maps (of 2 m spatial resolution) for an area of San Francisco, California, USA. The results were evaluated using descriptive statistics, correlation coefficient, RMSE, probability of success, boxplot and bivariate distribution function. Finally, FCLS was used for sub-pixel land cover analysis of the monthly WELD (Wen-enabled Landsat data) repository from 2008 to 2011 of North America. The abundance maps in conjunction with DMSP-OLS nighttime lights data were used to extract the urban land cover features and analyze their spatial-temporal growth.
Brando, Victoria; Castro-Zaballa, Santiago; Falconi, Atilio; Torterolo, Pablo; Migliaro, Eduardo R
2014-03-01
As a first step in a program designed to study the central control of the heart rate variability (HRV) during sleep, we conducted polysomnographic and electrocardiogram recordings on chronically-prepared cats during semi- restricted conditions. We found that the tachogram, i.e. the pattern of heart beat intervals (RR intervals) was deeply modified on passing from alert wakefulness through quiet wakefulness (QW) to sleep. While the tachogram showed a rhythmical pattern coupled with respiratory activity during non-REM sleep (NREM), it turned chaotic during REM sleep. Statistical analyses of the RR intervals showed that the mean duration increased during sleep. HRV measured by the standard deviation of normal RR intervals (SDNN) and by the square root of the mean squared difference of successive intervals (rMSSD) were larger during REM and NREM sleep than during QW. SD-1 (a marker of short- term variability) and SD-2 (a marker of long-term variability) measured by means of Poincaré plots increased during both REM and NREM sleep compared to QW. Furthermore, in the spectral analysis of RR intervals, the band of high frequency (HF) was larger in NREM and REM sleep in comparison to QW, whereas the band of low frequency (LF) was larger only during REM sleep in comparison to QW. The LF/HF ratio was larger during QW compared either with REM or NREM sleep. Finally, sample entropy analysis used as a measure of complexity, was higher during NREM in comparison to REM sleep. In conclusion, HRV parameters, including complexity, are deeply modified across behavioral states.
Towards the Procedure Automation of Full Stochastic Spectral Based Fatigue Analysis
Khurram Shehzad
2013-05-01
Full Text Available Fatigue is one of the most signiﬁcant failure modes for marine structures such as ships and offshore platforms. Among numerous methods for fatigue life estimation, spectral method is considered as the most reliable one due to its ability to cater different sea states as well as their probabilities of occurrence. However, spectral based simulation procedure itself is quite complex and numerically intensive owing to various critical technical details. Present research study is focused on the application and automation of spectral based fatigue analysis procedure for ship structure using ANSYS software with 3D liner sea keeping code AQWA. Ansys Parametric Design Language (APDL macros are created and subsequently implemented to automate the workflow of simulation process by reducing the time spent on non-value added repetitive activity. A MATLAB program based on direct calculation procedure of spectral fatigue is developed to calculate total fatigue damage. The automation procedure is employed to predict the fatigue life of a ship structural detail using wave scatter data of North Atlantic and Worldwide trade. The current work will provide a system for efficient implementation of stochastic spectral fatigue analysis procedure for ship structures.
Spectral saliency via automatic adaptive amplitude spectrum analysis
Wang, Xiaodong; Dai, Jialun; Zhu, Yafei; Zheng, Haiyong; Qiao, Xiaoyan
2016-03-01
Suppressing nonsalient patterns by smoothing the amplitude spectrum at an appropriate scale has been shown to effectively detect the visual saliency in the frequency domain. Different filter scales are required for different types of salient objects. We observe that the optimal scale for smoothing amplitude spectrum shares a specific relation with the size of the salient region. Based on this observation and the bottom-up saliency detection characterized by spectrum scale-space analysis for natural images, we propose to detect visual saliency, especially with salient objects of different sizes and locations via automatic adaptive amplitude spectrum analysis. We not only provide a new criterion for automatic optimal scale selection but also reserve the saliency maps corresponding to different salient objects with meaningful saliency information by adaptive weighted combination. The performance of quantitative and qualitative comparisons is evaluated by three different kinds of metrics on the four most widely used datasets and one up-to-date large-scale dataset. The experimental results validate that our method outperforms the existing state-of-the-art saliency models for predicting human eye fixations in terms of accuracy and robustness.
Micro-Raman Imaging for Biology with Multivariate Spectral Analysis
Malvaso, Federica
2015-05-05
Raman spectroscopy is a noninvasive technique that can provide complex information on the vibrational state of the molecules. It defines the unique fingerprint that allow the identification of the various chemical components within a given sample. The aim of the following thesis work is to analyze Raman maps related to three pairs of different cells, highlighting differences and similarities through multivariate algorithms. The first pair of analyzed cells are human embryonic stem cells (hESCs), while the other two pairs are induced pluripotent stem cells (iPSCs) derived from T lymphocytes and keratinocytes, respectively. Although two different multivariate techniques were employed, ie Principal Component Analysis and Cluster Analysis, the same results were achieved: the iPSCs derived from T-lymphocytes show a higher content of genetic material both compared with the iPSCs derived from keratinocytes and the hESCs . On the other side, equally evident, was that iPS cells derived from keratinocytes assume a molecular distribution very similar to hESCs.
Lin, J. Y.; Tsia, C. H.; Cheng, W. B.; Chin, S. J.; Lin, S. S.; Liang, C. W.
2015-12-01
The Nakamura's method, which calculates the ratios between horizontal and vertical component spectra of seismic signals (H/V), is widely used in the inland area. However, few related estimations were performed for the offshore area and little knowledge for the marine sediments were obtained. From 2013 to 2015, three passive ocean bottom seismometer (OBS) experiments were conducted in gas hydrate-rich area offshore SW Taiwan in the aim of acquiring information related to the physical properties of seafloor sediments. The H/V of the seafloor sediments in the three areas were estimated by using the ambient noise and seismic signal recorded by OBSs. The resonance frequency of each site was estimated from the main peak of H/V distribution and a range between 5 and 10 Hz were obtained. Based on the empirical law, this resonance frequency range should correspond to a sediment thickness of approximately several to ten of meters. This estimation is consistent with the thickness of the sedimentary cover imaged by chirp sonar survey, suggesting that the site response of seafloor is dominantly controlled by the unconsolidated sedimentary layer on the top of the sea bed. Remarkably, the H/V ratios obtained in our study area are much larger than that calculated for the inland areas. The magnification can reach as high as 50 to more than 100. This observation infers that the sea water movement might emphasize the horizontal motion of the marine sediments, which is crucial for the slope stability assessment. Moreover, for most stations located in the active margin, no distinct peak is observed for the H/V pattern calculated during earthquakes. However, in the passive margin, the H/V peak calculated from ambient noise and earthquakes is mostly identical. This phenomenon may suggest that relatively unclear sedimentary boundary exist in the active margin environment. Estimating H/V spectral ratios of data recorded by the OBSs deployed in the southwest Taiwan offshore area offers a
Spectral analysis of Gene co-expression network of Zebrafish
Jalan, S; Bhojwani, J; Li, B; Zhang, L; Lan, S H; Gong, Z
2012-01-01
We analyze the gene expression data of Zebrafish under the combined framework of complex networks and random matrix theory. The nearest neighbor spacing distribution of the corresponding matrix spectra follows random matrix predictions of Gaussian orthogonal statistics. Based on the eigenvector analysis we can divide the spectra into two parts, first part for which the eigenvector localization properties match with the random matrix theory predictions, and the second part for which they show deviation from the theory and hence are useful to understand the system dependent properties. Spectra with the localized eigenvectors can be characterized into three groups based on the eigenvalues. We explore the position of localized nodes from these different categories. Using an overlap measure, we find that the top contributing nodes in the different groups carry distinguished structural features. Furthermore, the top contributing nodes of the different localized eigenvectors corresponding to the lower eigenvalue reg...
Unsupervised linear spectral mixture analysis with AVIRIS data
GU Yan-feng; YANG Dong-yun; ZHANG Ye
2005-01-01
A new algorithm for unsupervised hyperspectral data unmixing is investigated, which includes a modified minimum noise fraction (MNF) transformation and independent component analysis (ICA). The modified MNF transformation is used to reduce noise and remove correlation between neighboring bands. Then the ICA is applied to unmix hyperspectral images, and independent endmembers are obtained from unmixed images by using post-processing which includes image segmentation based on statistical histograms and morphological operations. The experimental results demonstrate that this algorithm can identify endmembers resident in mixed pixels. Meanwhile, the results show the high computational efficiency of the modified MNF transformation. The time consumed by the modified method is almost one fifth of the traditional MNF transformation.
Spectral analysis of viscous static compressible fluid equilibria
Nunez, Manuel [Departamento de Analisis Matematico, Universidad de Valladolid, Valladolid (Spain)
2001-05-25
It is generally assumed that the study of the spectrum of the linearized Navier-Stokes equations around a static state will provide information about the stability of the equilibrium. This is obvious for inviscid barotropic compressible fluids by the self-adjoint character of the relevant operator, and rather easy for viscous incompressible fluids by the compact character of the resolvent. The viscous compressible linearized system, both for periodic and homogeneous Dirichlet boundary problems, satisfies neither condition, but it does turn out to be the generator of an immediately continuous, almost stable semigroup, which justifies the analysis of the spectrum as predictive of the initial behaviour of the flow. As for the spectrum itself, except for a unique negative finite accumulation point, it is formed by eigenvalues with negative real part, and nonreal eigenvalues are confined to a certain bounded subset of complex numbers. (author)
Spatio-temporal spectral analysis of a forced cylinder wake
D'Adamo, Juan; Wesfreid, José Eduardo
2011-01-01
The wake of a circular cylinder performing rotary oscillations is studied using hydrodynamic tunnel experiments at $Re=100$. Two-dimensional particle image velocimetry on the mid-plane perpendicular to the axis of cylinder is used to characterize the spatial development of the flow and its stability properties. The lock-in phenomenon that determines the boundaries between regions of the forcing parameter space were the wake is globally unstable or convectively unstable is scrutinized using the experimental data. A novel method based on the analysis of power density spectra of the flow allows us to give a detailed description of the forced wake, shedding light on the energy distribution in the different frequency components and in particular on a cascade-like mechanism evidenced for a high amplitude of the forcing oscillation. In addition, a calculation of the drag from the velocity field is performed, allowing us to relate the resulting force on the body to the wake properties.
Spectral analysis of musical sounds with emphasis on the piano
Koenig, David M
2014-01-01
There are three parts to this book which addresses the analysis of musical sounds from the viewpoint of someone at the intersection between physicists, engineers, piano technicians, and musicians. The reader is introduced to a variety of waves and a variety of ways of presenting, visualizing, and analyzing them in the first part. A tutorial on the tools used throughout the book accompanies this introduction. The mathematics behind the tools is left to the appendices. Part 2 is a graphical survey of the classical areas of acoustics that pertain to musical instruments: vibrating strings, bars, membranes, and plates. Part 3 is devoted almost exclusively to the piano. Several two- and three-dimensional graphical tools are introduced to study the following characteristics of pianos: individual notes and interactions among them, the missing fundamental, inharmonicity, tuning visualization, the different distribution of harmonic power for the various zones of the piano keyboard, and potential uses for quality contro...
Analysis UO2-CeO2 Powder Mixtures by the Binary-ratio Method
2002-01-01
The binary-ratio method is a special case in the X-ray fluorescence analysis and is suitable for themixed sample in which contains two compositions. A calibration curve of the analysis line intensity ratioversus concentration ratio is established, and is insensitive to reasonable variations in surface texture. The
Akita, Megumi; Ishii, Keiji; Kuwahara, Masayoshi; Tsubone, Hirokazu
2002-01-01
We established characteristics of power spectral analysis of heart rate variability, and assessed the diurnal variations of autonomic nervous function in guinea pigs. For this purpose, an electrocardiogram (ECG) was recorded for 24 hr from conscious and unrestrained guinea pigs using a telemetry system. There were two major spectral components, at low frequency (LF) and high frequency (HF) bands, in the power spectrum of HR variability. On the basis of these data, we defined two frequency bands of interest: LF (0.07-0.7 Hz) and HF (0.7-3.0 Hz). The power of LF was higher than that of HF in the normal guinea pigs. Atropine significantly reduced power at HF. Propranolol also significantly reduced power at LF. Furthermore, the decrease in the parasympathetic mechanism produced by atropine was reflected in a slight increase in the LF/HF ratio. The LF/HF ratio appeared to follow the reductions of sympathetic activity produced by propranolol. Autonomic blockade studies indicated that the HF component reflected parasympathetic activity and the LF/HF ratio seemed to be a convenient index of autonomic balance. Nocturnal patterns, in which the values of heart rate in the dark phase (20:00-06:00) were higher than those in the light phase (06:00-20:00), were observed. However, the HF, LF and the LF/HF ratio showed no daily pattern. These results suggest that the autonomic nervous function in guinea pigs has no clear circadian rhythmicity. Therefore, this information may be useful for future studies concerning the autonomic nervous function in this species.
V.N. Murashev
2015-06-01
Full Text Available In this paper the simulation of the silicon p-i-n-photodiodes spectral sensitivity characteristics was carried out. The analysis of the semiconductor material characteristics (the doping level, lifetime, surface recombination velocity, the construction and operation modes on the photosensitive structures characteristics in order to optimize them were investigated.
Spectral analysis of the light scattered from a chemically relaxing fluid: A ternary mixture
Carle, D.L.; Laidlaw, W.G.; Lekkerkerker, H.N.W.
1974-01-01
The spectral distribution of light scattered by a ternary fluid mixture containing two chemically reactive species and one nonreactive species is considered and a normal mode analysis is carried out for a range of k-values for which the pressure fluctuations are decoupled from those in entropy and c
Sex Differences in the Sleep EEG of Young Adults : Visual Scoring and Spectral Analysis
Dijk, Derk Jan; Beersma, Domien G.M.; Bloem, Gerda M.
1989-01-01
Baseline sleep of 13 men (mean age of 23.5 years) and 15 women (21.9 years) was analyzed. Visual scoring of the electroencephalograms (EEGs) revealed no significant differences between the sexes in the amounts of slow-wave sleep and rapid-eye-movement (REM) sleep. Spectral analysis, however, detecte
Biemann, Chris; Mukherjee, Animesh
2009-01-01
We study the global topology of the syntactic and semantic distributional similarity networks for English through the technique of spectral analysis. We observe that while the syntactic network has a hierarchical structure with strong communities and their mixtures, the semantic network has several tightly knit communities along with a large core without any such well-defined community structure.
Mass spectral analysis of C3 and C4 aliphatic amino acid derivatives.
Lawless, J. G.; Chadha, M. S.
1971-01-01
Diagnostic criteria are obtained for the distinction of alpha, beta, gamma, and N-methyl isomers of the C3 and C4 aliphatic amino acids, using mass spectral analysis of the derivatives of these acids. The use of deuterium labeling has helped in the understanding of certain fragmentation pathways.
All Night Spectral Analysis of EEG Sleep in Young Adult and Middle-Aged Male Subjects
Dijk, Derk Jan; Beersma, Domien G.M.; Hoofdakker, Rutger H. van den
1989-01-01
The sleep EEGs of 9 young adult males (age 20-28 years) and 8 middle-aged males (42-56 years) were analyzed by visual scoring and spectral analysis. In the middle-aged subjects power density in the delta, theta and sigma frequencies were attenuated as compared to the young subjects. In both age grou
Spectral Analysis and Musical Theory in Support to the Pianism of Samba and Related Genres
Luiz E. Castelões
2013-02-01
Full Text Available The present article proposes a methodology, which integrates spectral analysis, music theory, and instrumental practice, in order to approach the left-hand accompaniment of the samba's pianism to the muffled and loose tone of three different kinds of surdos (round shape drums used in the performance of samba.
[Spectral Analysis of Trace Fluorine Phase in Phosphogypsum].
Zhao, Hong-tao; Li, Hui-quan; Bao, Wei-jun; Wang, Chen-ye; Li, Song-geng; Lin, Wei-gang
2015-08-01
Phosphogypsum, which contains more than 90% of the calcium sulfate dehydrate (CaSO4 · 2H2O), is a kind of important renewable gypsum resources. Unlike the natural gypsum, however, phosphorus, fluorine, organic matter and other harmful impurities in phosphogypsum limit its practical use. To ascertain the existence form, content and phase distribution of trace fluoride in phosphogypsum has important theoretical values in removing trace fluoride effectively. In this present paper, the main existence form and phase distribution of trace fluoride in phosphogypsum was investigated by the combination of X-ray photoelectron spectroscopy (XPS) and Electron microprobe analysis (EMPA). The results show that trace fluoride phase mainly includes NaF, KF, CaF2, K2SiF6, Na2SiF6, Na3AlF6, K3AlF6, AlF3 · 3H2O, AlF2.3(OH)0.7 · H2O, Ca5(PO4)3F, Ca10(PO4)6F2. Among them, 4.83% of fluorine exists in the form of fluoride (NaF, KF, CaF2); Accordingly, 8.43% in the form of fluoride phosphate (Ca5(PO4)3F, Ca10(PO4)6F2); 12.21% in the form of fluorine aluminate (Na3AlF6, K3AlF6); 41.52% in the form of fluorosilicate (K2SiF6, Na2SiF6); 33.02% in the form of aluminum fluoride with crystal water (AlF3 · 3H2O, AlF2.3(OH)0.7 · H2O). In the analysis of phase constitution for trace elements in solid samples, the method of combining XPS and EMPA has more advantages. This study also provides theoretical basis for the removal of trace fluorine impurity and the effective recovery of fluorine resources.
Mise, Keiji; Sumi, Ayako; Kobayashi, Nobumichi; Torigoe, Toshihiko; Ohtomo, Norio
2009-01-01
We examined the usefulness of spectral analysis for investigating quantitatively the spatial pattern of pathologic tissue. To interpret the results obtained from real tissue, we constructed a two-dimensional spatial model of the tissue. Spectral analysis was applied to the spatial series data, which were obtained from the real tissue and model. From the results of spectral analysis, spatial patterns of the tissue and model were characterized quantitatively in reference to the frequencies and powers of the spectral peaks in power spectral densities (PSDs). The results for the model were essentially consistent with those for the tissue. It was concluded that the model was capable of adequately explaining the spatial pattern of the tissue. It is anticipated that spectral analysis will become a useful tool for characterizing the spatial pattern of the tissue quantitatively, resulting in an automated first screening of pathological specimens.
Kopriva, Ivica; Persin, Antun; Puizina-Ivić, Neira; Mirić, Lina
2010-07-02
This study was designed to demonstrate robust performance of the novel dependent component analysis (DCA)-based approach to demarcation of the basal cell carcinoma (BCC) through unsupervised decomposition of the red-green-blue (RGB) fluorescent image of the BCC. Robustness to intensity fluctuation is due to the scale invariance property of DCA algorithms, which exploit spectral and spatial diversities between the BCC and the surrounding tissue. Used filtering-based DCA approach represents an extension of the independent component analysis (ICA) and is necessary in order to account for statistical dependence that is induced by spectral similarity between the BCC and surrounding tissue. This generates weak edges what represents a challenge for other segmentation methods as well. By comparative performance analysis with state-of-the-art image segmentation methods such as active contours (level set), K-means clustering, non-negative matrix factorization, ICA and ratio imaging we experimentally demonstrate good performance of DCA-based BCC demarcation in two demanding scenarios where intensity of the fluorescent image has been varied almost two orders of magnitude.
Synthesis, spectral, computational and thermal analysis studies of metalloceftriaxone antibiotic
Masoud, Mamdouh S.; Ali, Alaa E.; Elasala, Gehan S.
2015-03-01
Binary ceftriaxone metal complexes of Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Hg(II) and six mixed metals complexes of (Fe, Cu), (Fe, Co), (Co, Ni), (Co, Cu), (Ni, Cu) and (Fe, Ni) were synthesized and characterized by elemental analysis, IR, electronic spectra, magnetic susceptibility and ESR spectra. The studies proved that the ligand has different combination modes and all complexes were of octahedral geometry. Molecular modeling techniques and quantum chemical methods have been performed for ceftriaxone to calculate charges, bond lengths, bond angles, dihedral angles, electronegativity (χ), chemical potential (μ), global hardness (η), softness (σ) and the electrophilicity index (ω). The thermal decomposition of the prepared metals complexes was studied by TGA, DTA and DSC techniques. The kinetic parameters and the reaction orders were estimated. The thermal decomposition of all the complexes ended with the formation of metal oxides and carbon residue as a final product except in case of Hg complex, sublimation occurs at the temperature range 297.7-413.7 °C so, only carbon residue was produced during thermal decomposition. The geometries of complexes may be altered from Oh to Td during the thermal decomposition steps. Decomposition mechanisms were suggested.
SPECTRAL FEATURE ANALYSIS FOR QUANTITATIVE ESTIMATION OF CYANOBACTERIA CHLOROPHYLL-A
Y. Lin
2016-06-01
Full Text Available In recent years, lake eutrophication caused a large of Cyanobacteria bloom which not only brought serious ecological disaster but also restricted the sustainable development of regional economy in our country. Chlorophyll-a is a very important environmental factor to monitor water quality, especially for lake eutrophication. Remote sensed technique has been widely utilized in estimating the concentration of chlorophyll-a by different kind of vegetation indices and monitoring its distribution in lakes, rivers or along coastline. For each vegetation index, its quantitative estimation accuracy for different satellite data might change since there might be a discrepancy of spectral resolution and channel center between different satellites. The purpose this paper is to analyze the spectral feature of chlorophyll-a with hyperspectral data (totally 651 bands and use the result to choose the optimal band combination for different satellites. The analysis method developed here in this study could be useful to recognize and monitor cyanobacteria bloom automatically and accrately. In our experiment, the reflectance (from 350nm to 1000nm of wild cyanobacteria in different consistency (from 0 to 1362.11ug/L and the corresponding chlorophyll-a concentration were measured simultaneously. Two kinds of hyperspectral vegetation indices were applied in this study: simple ratio (SR and narrow band normalized difference vegetation index (NDVI, both of which consists of any two bands in the entire 651 narrow bands. Then multivariate statistical analysis was used to construct the linear, power and exponential models. After analyzing the correlation between chlorophyll-a and single band reflectance, SR, NDVI respetively, the optimal spectral index for quantitative estimation of cyanobacteria chlorophyll-a, as well corresponding central wavelength and band width were extracted. Results show that: Under the condition of water disturbance, SR and NDVI are both suitable
Spectral Feature Analysis for Quantitative Estimation of Cyanobacteria Chlorophyll-A
Lin, Yi; Ye, Zhanglin; Zhang, Yugan; Yu, Jie
2016-06-01
In recent years, lake eutrophication caused a large of Cyanobacteria bloom which not only brought serious ecological disaster but also restricted the sustainable development of regional economy in our country. Chlorophyll-a is a very important environmental factor to monitor water quality, especially for lake eutrophication. Remote sensed technique has been widely utilized in estimating the concentration of chlorophyll-a by different kind of vegetation indices and monitoring its distribution in lakes, rivers or along coastline. For each vegetation index, its quantitative estimation accuracy for different satellite data might change since there might be a discrepancy of spectral resolution and channel center between different satellites. The purpose this paper is to analyze the spectral feature of chlorophyll-a with hyperspectral data (totally 651 bands) and use the result to choose the optimal band combination for different satellites. The analysis method developed here in this study could be useful to recognize and monitor cyanobacteria bloom automatically and accrately. In our experiment, the reflectance (from 350nm to 1000nm) of wild cyanobacteria in different consistency (from 0 to 1362.11ug/L) and the corresponding chlorophyll-a concentration were measured simultaneously. Two kinds of hyperspectral vegetation indices were applied in this study: simple ratio (SR) and narrow band normalized difference vegetation index (NDVI), both of which consists of any two bands in the entire 651 narrow bands. Then multivariate statistical analysis was used to construct the linear, power and exponential models. After analyzing the correlation between chlorophyll-a and single band reflectance, SR, NDVI respetively, the optimal spectral index for quantitative estimation of cyanobacteria chlorophyll-a, as well corresponding central wavelength and band width were extracted. Results show that: Under the condition of water disturbance, SR and NDVI are both suitable for quantitative
Xinjie Liu
2015-08-01
Full Text Available The full-spectrum Solar-Induced chlorophyll Fluorescence (SIF within the 650-800 nm spectral region can provide important information regarding physiological and biochemical activities in vegetation. This paper proposes a new Full-spectrum Spectral Fitting Method (F-SFM for the retrieval of SIF spectra based on Principal Components Analysis (PCA. Using F-SFM, both the full-spectrum reflectance and SIF within the 650-800 nm region were modeled by PCA based on a training dataset simulated by the Soil Canopy Observation, Photochemistry and Energy fluxes (SCOPE model, and the weighting coefficients of the principal components were estimated by the least-squares fitting method. An iterative process was employed to improve the accuracy of the estimation of the reflectance. In each iteration, the SIF spectra retrieved from the last run were removed from the total upwelling radiance to minimize the small contribution of the SIF to the apparent reflectance outside the absorption bands. Then, the F-SFM algorithm was tested using both simulated and field-measured data with different Spectral Resolutions (SRs and Signal-to-Noise Ratios (SNRs. For data with an SR of 0.3 nm and without noise, the Relative Root Mean Square Error (RRMSE was less than 14% within the spectral region that was studied, and the peak-value ratio (SIF735/SIF685 was accurately estimated with an RRMSE of 3.56%. In addition, the F-SFM algorithm proved less sensitive to the SR than the three-band Fraunhofer Line Discrimination (3 FLD and improved FLD (iFLD methods. In the case of the field spectral data with SRs of 3 nm and 0.3 nm, the double-peak shape and the diurnal variation trend of the SIF spectra could be reasonably reconstructed by F-SFM, and the retrieved SIF values at the O2-A and O2-B bands were consistent with those retrieved by 3FLD from data with a high SR (0.3 nm and SNR (1000. Therefore, the F-SFM method can provide full-spectrum SIF information with high accuracy even at
Liu, Dong; Hostetler, Chris; Miller, Ian; Cook, Anthony; Hair, Johnathan
2012-01-16
High spectral resolution lidars (HSRLs) have shown great value in aircraft aerosol remote sensing application and are planned for future satellite missions. A compact, robust, quasi-monolithic tilted field-widened Michelson interferometer is being developed as the spectral discrimination filter for an second-generation HSRL(HSRL-2) at NASA Langley Research Center. The Michelson interferometer consists of a cubic beam splitter, a solid arm and an air arm. Piezo stacks connect the air arm mirror to the body of the interferometer and can tune the interferometer within a small range. The whole interferometer is tilted so that the standard Michelson output and the reflected complementary output can both be obtained. In this paper, the transmission ratio is proposed to evaluate the performance of the spectral filter for HSRL. The transmission ratios over different types of system imperfections, such as cumulative wavefront error, locking error, reflectance of the beam splitter and anti-reflection coatings, system tilt, and depolarization angle are analyzed. The requirements of each imperfection for good interferometer performance are obtained.
ON SPECTRAL METHODS FOR VOLTERRA INTEGRAL EQUATIONS AND THE CONVERGENCE ANALYSIS
Tao Tang; Xiang Xu; Jin Cheng
2008-01-01
The main purpose of this work is to provide a novel numerical approach for the Volterra integral equations based on a spectral approach. A Legendre-collocation method is pro-posed to solve the Volterra integral equations of the second kind. We provide a rigorous error analysis for the proposed method, which indicates that the numerical errors decay exponentially provided that the kernel function and the source function are sufficiently smooth. Numerical results confirm the theoretical prediction of the exponential rate of convergence. The result in this work seems to be the first successful spectral approach (with theoretical justification) for the Volterra type equations.
The spectral analysis of syllables in patients using dentures.
Jindra, Petr; Eber, Miroslav; Pesák, Josef
2002-12-01
Changes in the oral cavity resulting from the loss of teeth and the ensuing reconstruction of a set of teeth by dentures (partial or complete) may cause changes in the speech and voice of the patient. The aim of the present investigation was to study the changes in speech and voice in patients suffering from teeth loss and the degree of speech improvement using dentures. Voice and speech parameters of a set of tested syllables were analysed in 10 patients at the 2nd Clinic of Stomatology. The analysis was carried out by means of an FFT, SoundForge 5.0 programme. Differently expressed acoustic changes in both consonants and vowels were ascertained in a percentage of the patients under examination. These concerned especially the sibilant ("s", "(see text)"), labiodental ("f", "v") and vibrating ("r", "(see text)") consonants. Changes in the FFT spectrum and air leakage in constrictive consonants were also found. In some patients the vowels, especially the closed ones ("i", "u"), may change their fundamental frequency and show noise admixture manifested as a blurred delimitation of the formants. A denture should, inter alia, render it possible for the patient to produce the same articulation to which he/she had been accustomed before the loss of teeth. For the construction of dentures the most important factors from a phonetic point of view appear to be the following: overbite, overjet, the height of the plate, the thickness of the palatal material, the incisor position, and the modelling of the ruga palatina on the hard palate. In case of wrong denture construction the acoustic changes may continue, resulting in the patient's stress load dependent upon sex, age, psychic condition and seriousness of the problem.
Spectral and gravimetric analysis of completely oxidized amalgam systems.
Mueller, H J
1980-01-01
Analysis of the soluble solution species, insoluble solution precipitate, adherent corrosion products, and microstructural changes of the substrate amalgam after selected polarization to -0.2v and +0.5v in a chloride solution is reported. Results indicate only small concentrations of soluble species, high concentrations of a Sn insoluble solution precipitate at -0.2v, and high concentrations of a Cu precipitate at +0.5v, related to CuCl2 . 3 Cu (OH)2. The completely oxidized amalgam microstructure indicates a thin outermost layer of predominantly Sn--Cl, a thick corroded layer of Ag-Sn-Hg-Cl, and the remaining substrate amalgam. The compound of (SnO) 160 is also associated with the thick corroded layer. The microstructure of the substrate amalgam exhibits, besides the normally occurring phases and products, four new phases or alterations due to the redistribution of Sn, Cl and 0 from the gamma-2 corrosion products, (1) the reappearance of voids, (2) a grey Ag-Sn-Cl phase with and without Cu localized at specific sites in the gamma-1 matrix, (3) dark areas or partially filled voids containing the same elements as in (2) and formerly occupied by the gamma-2 products, and (4) a Cu-rich phase from the deterioration of the Cu6Sn5 phase and also included within the matrix. These changes, particularly (1), (2) and (3) occur with the onset of the gamma-1 deterioration. Unreacted Ag3Sn including the additions of the Cu3Sn component is the last phase to be attacked in the composite amalgam.
RXTE Observation of Cygnus X-1 Spectral Analysis
Dove, J. B.; Wilms, Joern; Nowak, M. A.; Vaughan, B. A.; Begelman, M. C.
1998-01-01
We present the results of the analysis of the broad-band spectrum of Cygnus X-1 from 3.0 to 200 keV, using data from a 10 ksec observation by the Rossi X-ray Timing Explorer. Although the spectrum can be well described phenomenologically by an exponentially cut-off power law (photon index Gamma = 1.45+0.01 -0.02 , e-folding energy e(sub f) = 162+9 -8 keV, plus a deviation from a power law that formally can be modeled as a thermal blackbody, with temperature kT(sub BB) = 1.2 +0.0 -0.1 keV), the inclusion of a reflection component does not improve the fit. As a physical description of this system, we apply the accretion disc corona (ADC) models. A slab-geometry ADC model is unable to describe the data. However, a spherical corona, with a total optical depth tau- = 1.6 + or - 0.1 and an average temperature kTc = 87 + or - 5 keV, surrounded by an exterior cold disc, does provide a good description of the data (X red (exp 2) = 1.55). These models deviate from the data bv up to 7% in the 5-10 keV range. However, considering how successfully the spherical corona reproduces the 10-200 keV data, such "photon-starved" coronal geometries seem very promising for explaining the accretion processes of Cygnus X-1.
Wang, Qi, E-mail: wq20@hotmail.com; Shi, Gaofeng, E-mail: gaofengs62@sina.com; Qi, Xiaohui, E-mail: qixiaohui1984@163.com; Fan, Xueli, E-mail: 407849960@qq.com; Wang, Lijia, E-mail: 893197597@qq.com
2014-10-15
Highlights: • We establish a feasible method using the virtual spectral curves (VSC) to differentiate focal liver lesions using DECT. • Our study shows the slope of the VSC can be used to differentiate between hemangioma, HCC, metastasis and cyst. • Importantly, the diagnostic specificities associated with using the slope to diagnose both hemangioma and cysts were 100%. - Abstract: Objective: To assess the usefulness of the spectral curve slope of dual-energy CT (DECT) for differentiating between hepatocellular carcinoma (HCC), hepatic metastasis, hemangioma (HH) and cysts. Methods: In total, 121 patients were imaged in the portal venous phase using dual-energy mode. Of these patients, 23 patients had HH, 28 patients had HCC, 40 patients had metastases and 30 patients had simple cysts. The spectral curves of the hepatic lesions were derived from the 40–190 keV levels of virtual monochromatic spectral imaging. The spectral curve slopes were calculated from 40 to 110 keV. The slopes were compared using the Kruskal–Wallis test. Receiver operating characteristic curves (ROC) were used to determine the optimal cut-off value of the slope of the spectral curve to differentiate between the lesions. Results: The spectral curves of the four lesion types had different baseline levels. The HH baseline level was the highest followed by HCC, metastases and cysts. The slopes of the spectral curves of HH, HCC, metastases and cysts were 3.81 ± 1.19, 1.49 ± 0.57, 1.06 ± 0.76 and 0.13 ± 0.17, respectively. These values were significantly different (P < 0.008). Based on ROC analysis, the respective diagnostic sensitivity and specificity were 87% and 100% for hemangioma (cut-off value ≥ 2.988), 82.1% and 65.9% for HCC (cut-off value 1.167–2.998), 65.9% and 59% for metastasis (cut-off value 0.133–1.167) and 44.4% and 100% for cysts (cut-off value ≤ 0.133). Conclusion: Quantitative analysis of the DECT spectral curve in the portal venous phase can be used to
Spectral Analysis of Biosignals to Evaluate Heart Activity due to the Consumption of Energy Drinks
Md. Bashir Uddin
2016-08-01
Full Text Available The heart activity is clearly evaluated in this study by analyzing spectral or frequency components of three Biosignals such as ECG, PPG and blood perfusion signal. This study is done with several healthy human subjects who are totally free from any type of cardiovascular diseases. ECG and PPG recordings were performed with electrode lead set and pulse transducer respectively connected to the same MP36 (Biopac, USA data acquisition unit. LDF measurements were performed with skin surface probe connected to LDF100C module on middle finger tip. This LDF module was connected to MP150 (Biopac, USA data acquisition unit. ECG, PPG and blood perfusion signal recordings were performed before and after having energy drinks available in Bangladesh. After consuming energy drinks, it is observed that the spectral or frequency components for ECG as well as PPG signal decreases with a significant rate from the instant of having ED. That is, the spectral parameters of heart activity decrease due to the consumption of energy drinks. The spectral analysis of LDF signal also results similar type of decrement in their spectral parameters for same type of energy drinks consumption. These results reflect adverse impacts of energy drinks consumption on heart activity.
Manja Reimann
Full Text Available BACKGROUND: The assessment of baroreflex sensitivity (BRS has emerged as prognostic tool in cardiology. Although available computer-assisted methods, measuring spontaneous fluctuations of heart rate and blood pressure in the time and frequency domain are easily applicable, they do not allow for quantification of BRS during cardiovascular adaption processes. This, however, seems an essential criterion for clinical application. We evaluated a novel algorithm based on trigonometric regression regarding its ability to map dynamic changes in BRS and autonomic tone during cardiovascular provocation in relation to gender and age. METHODOLOGY/PRINCIPAL FINDINGS: We continuously recorded systemic arterial pressure, electrocardiogram and respiration in 23 young subjects (25+/-2 years and 22 middle-aged subjects (56+/-4 years during cardiovascular autonomic testing (metronomic breathing, Valsalva manoeuvre, head-up tilt. Baroreflex- and spectral analysis was performed using the algorithm of trigonometric regressive spectral analysis. There was an age-related decline in spontaneous BRS and high frequency oscillations of RR intervals. Changes in autonomic tone evoked by cardiovascular provocation were observed as shifts in the ratio of low to high frequency oscillations of RR intervals and blood pressure. Respiration at 0.1 Hz elicited an increase in BRS while head-up tilt and Valsalva manoeuvre resulted in a downregulation of BRS. The extent of autonomic adaption was in general more pronounced in young individuals and declined stronger with age in women than in men. CONCLUSIONS/SIGNIFICANCE: The trigonometric regressive spectral analysis reliably maps age- and gender-related differences in baroreflex- and autonomic function and is able to describe adaption processes of baroreceptor circuit during cardiovascular stimulation. Hence, this novel algorithm may be a useful screening tool to detect abnormalities in cardiovascular adaption processes even when
Yingbin Deng
2016-04-01
Full Text Available Multiple endmember spectral mixture analysis (MESMA has been widely applied for estimating fractional land covers from remote sensing imagery. MESMA has proven effective in addressing inter-class and intra-class endmember variability by allowing pixel-specific endmember combinations. This method, however, assumes that each land cover type has an equal probability of being included in the model, and the one with the least estimation error (e.g., root mean square error was chosen as the “best-fit” model. Such an approach may mistakenly include a land cover class in the model and overestimate its abundance, or it might omit a class from the model and subsequently lead to underestimation. To address this problem, this paper developed a land cover class-based multiple endmember spectral mixture analysis (C-MESMA method. In particular, a support vector machine (SVM method with reflectance spectra and spectral indices, including the normalized difference vegetation index (NDVI, the biophysical composition index (BCI, and the ratio normalized difference soil index (RNDSI, were employed to classify the image into six land cover classes: pure impervious surface area (ISA, pure vegetation, pure soil, ISA-vegetation, vegetation-soil, and vegetation-ISA-soil. With the information of land cover classes, an individual MESMA method was applied to each mixed class. Finally, the fractional maps were derived through integrating land cover fractions of each land cover class. Quantitative analysis of the resulting percent ISA (%ISA and comparative analyses with traditional MESMA indicate that C-MESMA improved the estimation accuracy of %ISA.
Alvarez-Estevez, Diego; Moret-Bonillo, Vicente
2016-04-01
Some approaches have been published in the past using Heart Rate Variability (HRV) spectral features for the screening of Sleep Apnea-Hypopnea Syndrome (SAHS) patients. However there is a big variability among these methods regarding the selection of the source signal and the specific spectral components relevant to the analysis. In this study we investigate the use of the Heart Timing (HT) as the source signal in comparison to the classical approaches of Heart Rate (HR) and Heart Period (HP). This signal has the theoretical advantage of being optimal under the Integral Pulse Frequency Modulation (IPFM) model assumption. Only spectral bands defined as standard for the study of HRV are considered, and for each method the so-called LF/HF and VLFn features are derived. A comparative statistical analysis between the different resulting methods is performed, and subject classification is investigated by means of ROC analysis and a Naïve-Bayes classifier. The standard Apnea-ECG database is used for validation purposes. Our results show statistical differences between SAHS patients and controls for all the derived features. In the subject classification task the best performance in the testing set was obtained using the LF/HF ratio derived from the HR signal (Area under ROC curve=0.88). Only slight differences are obtained due to the effect of changing the source signal. The impact of using the HT signal in this domain is therefore limited, and has not shown relevant differences with respect to the use of the classical approaches of HR or HP.
Spectral quantitation by principal component analysis using complex singular value decomposition.
Elliott, M A; Walter, G A; Swift, A; Vandenborne, K; Schotland, J C; Leigh, J S
1999-03-01
Principal component analysis (PCA) is a powerful method for quantitative analysis of nuclear magnetic resonance spectral data sets. It has the advantage of being model independent, making it well suited for the analysis of spectra with complicated or unknown line shapes. Previous applications of PCA have required that all spectra in a data set be in phase or have implemented iterative methods to analyze spectra that are not perfectly phased. However, improper phasing or imperfect convergence of the iterative methods has resulted in systematic errors in the estimation of peak areas with PCA. Presented here is a modified method of PCA, which utilizes complex singular value decomposition (SVD) to analyze spectral data sets with any amount of variation in spectral phase. The new method is shown to be completely insensitive to spectral phase. In the presence of noise, PCA with complex SVD yields a lower variation in the estimation of peak area than conventional PCA by a factor of approximately 2. The performance of the method is demonstrated with simulated data and in vivo 31P spectra from human skeletal muscle.
Spectral Analysis of Acceleration Data for Detection of Generalized Tonic-Clonic Seizures
Joo, Hyo Sung; Han, Su-Hyun; Lee, Jongshill; Jang, Dong Pyo; Kang, Joong Koo; Woo, Jihwan
2017-01-01
Generalized tonic-clonic seizures (GTCSs) can be underestimated and can also increase mortality rates. The monitoring devices used to detect GTCS events in daily life are very helpful for early intervention and precise estimation of seizure events. Several studies have introduced methods for GTCS detection using an accelerometer (ACM), electromyography, or electroencephalography. However, these studies need to be improved with respect to accuracy and user convenience. This study proposes the use of an ACM banded to the wrist and spectral analysis of ACM data to detect GTCS in daily life. The spectral weight function dependent on GTCS was used to compute a GTCS-correlated score that can effectively discriminate between GTCS and normal movement. Compared to the performance of the previous temporal method, which used a standard deviation method, the spectral analysis method resulted in better sensitivity and fewer false positive alerts. Finally, the spectral analysis method can be implemented in a GTCS monitoring device using an ACM and can provide early alerts to caregivers to prevent risks associated with GTCS. PMID:28264522
Haefner, R.J.; Sheets, R.A.; Andrews, R.E.
2010-01-01
The horizontal-to-vertical spectral ratio (HVSR) seismic method involves analyzing measurements of ambient seismic noise in three dimensions to determine the fundamental site resonance frequency. Resonance is excited by the interaction of surface waves (Rayleigh and Love) and body waves (vertically incident shear) with the high-contrast acoustic impedance boundary at the bedrock-sediment interface. Measurements were made to determine the method's utility for estimating thickness of unconsolidated glacial sediments at 18 locations at the South Well Field, Franklin County, OH, and at six locations in Pickaway County where sediment thickness was already known. Measurements also were made near a high-capacity production well (with pumping on and off ) and near a highway and a limestone quarry to examine changes in resonance frequencies over a 20-hour period. Although the regression relation for resonance frequency and sediment thickness had a relatively low r 2(0.322), estimates of sediment thickness were, on average, within 14 percent of known thicknesses. Resonance frequencies for pumping on and pumping off were identical, although the amplitude of the peak was nearly double under pumping conditions. Resonance frequency for the 20-hour period did not change, but the amplitude of the peak changed considerably, with a maximum amplitude in the early afternoon and minimum in the very early morning hours. Clay layers within unconsolidated sediments may influence resonance frequency and the resulting regression equation, resulting in underestimation of sediment thickness; however, despite this and other complicating factors, hydrogeologists should consider this method when thickness data are needed for unconsolidated sediments. ?? 2011 by The Ohio Academy of Science. All Rights Reserved.
Dao, L; Lucotte, B; Glancy, B; Chang, L-C; Hsu, L-Y; Balaban, R S
2014-11-01
In conventional multi-probe fluorescence microscopy, narrow bandwidth filters on detectors are used to avoid bleed-through artefacts between probes. The limited bandwidth reduces the signal-to-noise ratio of the detection, often severely compromising one or more channels. Herein, we describe a process of using independent component analysis to discriminate the position of different probes using only a dichroic mirror to differentiate the signals directed to the detectors. Independent component analysis was particularly effective in samples where the spatial overlap between the probes is minimal, a very common case in cellular microscopy. This imaging scheme collects nearly all of the emitted light, significantly improving the image signal-to-noise ratio. In this study, we focused on the detection of two fluorescence probes used in vivo, NAD(P)H and ANEPPS. The optimal dichroic mirror cutoff frequency was determined with simulations using the probes spectral emissions. A quality factor, defined as the cross-channel contrast-to-noise ratio, was optimized to maximize signals while maintaining spatial discrimination between the probes after independent component analysis post-processing. Simulations indicate that a ∼3 fold increase in signal-to-noise ratio using the independent component analysis approach can be achieved over the conventional narrow-band filtering approach without loss of spatial discrimination. We confirmed this predicted performance from experimental imaging of NAD(P)H and ANEPPS in mouse skeletal muscle, in vivo. For many multi-probe studies, the increased sensitivity of this 'full bandwidth' approach will lead to improved image quality and/or reduced excitation power requirements.
Effect of Coupling on the Epidemic Threshold in Interconnected Complex Networks: A Spectral Analysis
Sahneh, Faryad Darabi; Chowdhury, Fahmida N
2012-01-01
In epidemic modeling, the term infection strength indicates the ratio of infection rate and cure rate. If the infection strength is higher than a certain threshold -- which we define as the epidemic threshold - then the epidemic spreads through the population and persists in the long run. For a single generic graph representing the contact network of the population under consideration, the epidemic threshold turns out to be equal to the inverse of the spectral radius of the contact graph. However, in a real world scenario it is not possible to isolate a population completely: there is always some interconnection with another network, which partially overlaps with the contact network. Results for epidemic threshold in interconnected networks are limited to homogeneous mixing populations and degree distribution arguments. In this paper, we adopt a spectral approach. We show how the epidemic threshold in a given network changes as a result of being coupled with another network with fixed infection strength. In o...
Analysis of Spectral Features of EEG during four different Cognitive Tasks
S.BAGYARAJ
2014-05-01
Full Text Available Cognition is a group of information processing activities that involves the visual attention, visual awareness, problem solving and decision making. Finding the cognitive task related regional cerebral activations are of great interest among researchers in cognitive neuroscience. In this study four different types of cognitive tasks, namely tracking pendulum movement and counting, red flash counting, sequential subtraction, spot the difference is performed by 32 subjects and the EEG signals are acquired by using 24 channels RMS EEG-32 Super Spec machine. The analyses of the EEG signal are done by using well known spectral methods. The band powers are calculated in the frequency domain by using the Welch method. The task- relaxes relative band power values and the ratios of theta band power/ beta band power are the two variables used to find the regional cerebral activations during the four different cognitive tasks. The statistical paired t test is used to evaluate the significant difference between the particular tasks related cerebral activations and relaxation. The statistical significance level is set at p< 0.05. During the tracking pendulum movement and counting task, the cerebral activations are found to be bilateral prefrontal, frontal, right central and temporal regions. Red flash counting task has activations in bilateral prefrontal, frontal, right central, right parietal and right occipital lobes. Bilateral prefrontal regions are activated during the sequence subtraction task. The spot the difference task has activations in the left and right prefrontal cortex. The unique and common activations regions for the selected four different cognitive tasks are found to be left and right prefrontal cortex. The pre frontal lobe electrodes namely Fp1 & Fp2 can be used as the recording electrodes for detailed cognitive task analysis were cerebral activations are observed when compared with the other cerebral regions.
Using of Ratio Analysis for Identification of Opportunities within the Early Notification System
Agnieszka Ordys
2007-10-01
Full Text Available The article discusses the use of ratio analysis as a part of early warning and notification systems to identify potential opportunities. The basic issues related to ratio analysis and early notification systems are introduced. In order to exemplify the problem the article presents the analysis of 19 food sector companies listed on the Warsaw Stock Exchange basing on the Altmans classic Z-score model.
Correlative Spectral Analysis of Gamma-Ray Bursts using Swift-BAT and GLAST-GBM
Stamatikos, Michael; Band, David L
2008-01-01
We discuss the preliminary results of spectral analysis simulations involving anticipated correlated multi-wavelength observations of gamma-ray bursts (GRBs) using Swift's Burst Alert Telescope (BAT) and the Gamma-Ray Large Area Space Telescope's (GLAST) Burst Monitor (GLAST-GBM), resulting in joint spectral fits, including characteristic photon energy (Epeak) values, for a conservative annual estimate of ~30 GRBs. The addition of BAT's spectral response will (i) complement in-orbit calibration efforts of GBM's detector response matrices, (ii) augment GLAST's low energy sensitivity by increasing the ~20-100 keV effective area, (iii) facilitate ground-based follow-up efforts of GLAST GRBs by increasing GBM's source localization precision, and (iv) help identify a subset of non-triggered GRBs discovered via off-line GBM data analysis. Such multi-wavelength correlative analyses, which have been demonstrated by successful joint-spectral fits of Swift-BAT GRBs with other higher energy detectors such as Konus-WIND ...
Chemometric analysis for near-infrared spectral detection of beef in fish meal
Yang, Chun-Chieh; Garrido-Novell, Cristóbal; Pérez-Marín, Dolores; Guerrero-Ginel, José E.; Garrido-Varo, Ana; Kim, Moon S.
2015-05-01
This paper reports the chemometric analysis of near-infrared spectra drawn from hyperspectral images to develop, evaluate, and compare statistical models for the detection of beef in fish meal. There were 40 pure-fish meal samples, 15 pure-beef meal samples, and 127 fish/beef mixture meal samples prepared for hyperspectral line-scan imaging by a machine vision system. Spectral data for 3600 pixels per sample, in which individual spectra was obtain, were retrieved from the region of interest (ROI) in every sample image. The spectral data spanning 969 nm to 1551 nm (across 176 spectral bands) were analyzed. Statistical models were built using the principal component analysis (PCA) and the partial least squares regression (PLSR) methods. The models were created and developed using the spectral data from the purefish meal and pure-beef meal samples, and were tested and evaluated using the data from the ROI in the mixture meal samples. The results showed that, with a ROI as large as 3600 pixels to cover sufficient area of a mixture meal sample, the success detection rate of beef in fish meal could be satisfactory 99.2% by PCA and 98.4% by PLSR.
Duplex-Doppler spectral analysis in the physiopathology of the temporomandibular joint.
Marini, M; Odoardi, G L; Bolle, G; Tartaglia, P
1994-01-01
We introduce a new method of analysis of the normal and abnormal behavior of the TMJ, using a duplex-doppler spectral analysis. The method consists in monitoring the joint movement by means of a study of the Fourier transformed signals, which give information on the velocity distribution of the condylo-meniscal complex during the opening and closing phases of the jaw. Using repeated sampling over short time intervals we get a detailed description of the motion which allows to discriminate the normal and abnormal action of the condylomeniscal complex. We are able to identify various physiopathological conditions, among which opening and/or closing clicks, complex locking conditions and anomalies related to an asymmetrical behavior during the operation cycle. Duplex-doppler spectral analysis is correlated to a clinical examination in order to define various classes of anomalies.
2-D Prony-Huang Transform: A New Tool for 2-D Spectral Analysis
Schmitt, Jérémy; Borgnat, Pierre; Flandrin, Patrick; Condat, Laurent
2014-01-01
This work proposes an extension of the 1-D Hilbert Huang transform for the analysis of images. The proposed method consists in (i) adaptively decomposing an image into oscillating parts called intrinsic mode functions (IMFs) using a mode decomposition procedure, and (ii) providing a local spectral analysis of the obtained IMFs in order to get the local amplitudes, frequencies, and orientations. For the decomposition step, we propose two robust 2-D mode decompositions based on non-smooth convex optimization: a "Genuine 2-D" approach, that constrains the local extrema of the IMFs, and a "Pseudo 2-D" approach, which constrains separately the extrema of lines, columns, and diagonals. The spectral analysis step is based on Prony annihilation property that is applied on small square patches of the IMFs. The resulting 2-D Prony-Huang transform is validated on simulated and real data.
Determination of defect in rotor of induction machine by spectral analysis of stator phase current
Myrteza Braneshi
2010-10-01
Full Text Available Induction motors are important part of safe and efficient running of any industrial plant. These motors are often used in industrial applications thanks to their usability and their robustness. Faults and failures of induction machine can lead to excessive downtimes processes; generate large losses in revenues and long term maintenance. Early detection of motor abnormalities would help avoiding costly breakdowns. In this paper a diagnostic technique of induction motor broken rotor bars is presented. The applied method is the so-called Motor Current Signature Analysis (MCSA which utilized the results of spectral analysis of the stator current. The broken rotor bars and rings will cause twice slip frequency side bands around the supplying frequency. The fault detection method consists in monitoring of stator phase current spectrum. Twice slip frequency side bands around the main frequency detected by spectral analysis is an indicator of the broken bars. The experimental results show the efficiency of the method.
MS fragment isotope ratio analysis for evaluation of citrus essential oils by HRGC-MS.
Satake, Atsushi; Furukawa, Kiyoshi; Ueno, Takao; Ukeda, Hiroyuki; Sawamura, Masayoshi
2004-02-01
To evaluate the origin of citrus essential oils, the isotope ratio of fragment peaks on HRGC-MS of the volatile compounds from various citrus oils was measured. The MS fragment ratio was found by the ratio of fragment peak intensity, m+1/m (m/z). This ratio reflects the isotope effect of volatile compounds, that is, it provides information about locality, quality, and species for essential oils. Multivariate analysis based on the MS fragment ratio of monoterpene hydrocarbons clearly distinguished three citrus species, yuzu, lemon, and lime. The carbonyl fractions were also extracted from citrus essential oils by the sodium hydrogensulfite method. The isotope ratio of MS fragments of octanal, nonanal, and decanal was also examined. The results suggest that there was no significant difference in the individual fragment isotope ratios of the three aldehydes.
Joint Spectral Analysis for Early Bright X-ray Flares of -Ray Bursts with Swift BAT and XRT Data
Fang-Kun Peng; You-Dong Hu; Xiang-Gao Wang; Rui-Jing Lu; En-Wei Liang
2014-09-01
A joint spectral analysis for early bright X-ray flares that were simultaneously observed with Swift BAT and XRT are present. Both BAT and XRT lightcurves of these flares are correlated. Our joint spectral analysis shows that the radiations in the two energy bands are from the same spectral component, which can be well fitted with a single power-law. Except for the flares in GRBs 060904B and 100906A, the photon spectral indices are < 2.0, indicating the peak energies (p) of the prompt -rays should be above the high energy end of the BAT band.
The spectral analysis of motion: An "open field" activity test example
Obradović Z.
2013-01-01
Full Text Available In this work we have described the new mathematical approach, with spectral analysis of the data to evaluate position and motion in the „„open field““ experiments. The aim of this work is to introduce several new parameters mathematically derived from experimental data by means of spectral analysis, and to quantitatively estimate the quality of the motion. Two original software packages (TRACKER and POSTPROC were used for transforming a video data to a log file, suitable for further computational analysis, and to perform analysis from the log file. As an example, results obtained from the experiments with Wistar rats in the „open field“ test are included. The test group of animals was treated with diazepam. Our results demonstrate that all the calculated parameters, such as movement variability, acceleration and deceleration, were significantly lower in the test group compared to the control group. We believe that the application of parameters obtained by spectral analysis could be of great significance in assessing the locomotion impairment in any kind of motion. [Projekat Ministarstva nauke Republike Srbije, br. III41007 i br. ON174028
Bernabe, Sergio; Igual, Francisco D.; Botella, Guillermo; Prieto-Matias, Manuel; Plaza, Antonio
2015-10-01
In the last decade, the issue of endmember variability has received considerable attention, particularly when each pixel is modeled as a linear combination of endmembers or pure materials. As a result, several models and algorithms have been developed for considering the effect of endmember variability in spectral unmixing and possibly include multiple endmembers in the spectral unmixing stage. One of the most popular approach for this purpose is the multiple endmember spectral mixture analysis (MESMA) algorithm. The procedure executed by MESMA can be summarized as follows: (i) First, a standard linear spectral unmixing (LSU) or fully constrained linear spectral unmixing (FCLSU) algorithm is run in an iterative fashion; (ii) Then, we use different endmember combinations, randomly selected from a spectral library, to decompose each mixed pixel; (iii) Finally, the model with the best fit, i.e., with the lowest root mean square error (RMSE) in the reconstruction of the original pixel, is adopted. However, this procedure can be computationally very expensive due to the fact that several endmember combinations need to be tested and several abundance estimation steps need to be conducted, a fact that compromises the use of MESMA in applications under real-time constraints. In this paper we develop (for the first time in the literature) an efficient implementation of MESMA on different platforms using OpenCL, an open standard for parallel programing on heterogeneous systems. Our experiments have been conducted using a simulated data set and the clMAGMA mathematical library. This kind of implementations with the same descriptive language on different architectures are very important in order to actually calibrate the possibility of using heterogeneous platforms for efficient hyperspectral imaging processing in real remote sensing missions.
Clues to Coral Reef Ecosystem Health: Spectral Analysis Coupled with Radiative Transfer Modeling
Guild, L.; Ganapol, B.; Kramer, P.; Armstrong, R.; Gleason, A.; Torres, J.; Johnson, L.; Garfield, N.
2003-12-01
Coral reefs are among the world's most productive and biologically rich ecosystems and are some of the oldest ecosystems on Earth. Coralline structures protect coastlines from storms, maintain high diversity of marine life, and provide nurseries for marine species. Coral reefs play a role in carbon cycling through high rates of organic carbon metabolism and calcification. Coral reefs provide fisheries habitat that are the sole protein source for humans on remote islands. Reefs respond immediately to environmental change and therefore are considered "canaries" of the oceans. However, the world's reefs are in peril: they have shrunk 10-50% from their historical extent due to climate change and anthropogenic activity. An important contribution to coral reef research is improved spectral distinction of reef species' health where anthropogenic activity and climate change impacts are high. Relatively little is known concerning the spectral properties of coral or how coral structures reflect and transmit light. New insights into optical processes of corals under stressed conditions can lead to improved interpretation of airborne and satellite data and forecasting of immediate or long-term impacts of events such as bleaching and disease in coral. We are investigating the spatial and spectral resolution required to detect remotely changes in reef health by coupling spectral analysis of in situ spectra and airborne spectral data with a new radiative transfer model called CorMOD2. Challenges include light attenuation by the water column, atmospheric scattering, and scattering caused by the coral themselves that confound the spectral signal. In CorMOD2, input coral reflectance measurements produce modeled absorption through an inversion at each visible wavelength. The first model development phase of CorMOD2 imposes a scattering baseline that is constant regardless of coral condition, and further specifies that coral is optically thick. Evolution of CorMOD2 is towards a coral
EEG Resolutions in Detecting and Decoding Finger Movements from Spectral Analysis
Ran eXiao
2015-09-01
Full Text Available Mu/beta rhythms are well-studied brain activities that originate from sensorimotor cortices. These rhythms reveal spectral changes in alpha and beta bands induced by movements of different body parts, e.g. hands and limbs, in electroencephalography (EEG signals. However, less can be revealed in them about movements of different fine body parts that activate adjacent brain regions, such as individual fingers from one hand. Several studies have reported spatial and temporal couplings of rhythmic activities at different frequency bands, suggesting the existence of well-defined spectral structures across multiple frequency bands. In the present study, spectral principal component analysis (PCA was applied on EEG data, obtained from a finger movement task, to identify cross-frequency spectral structures. Features from identified spectral structures were examined in their spatial patterns, cross-condition pattern changes, detection capability of finger movements from resting, and decoding performance of individual finger movements in comparison to classic mu/beta rhythms. These new features reveal some similar, but more different spatial and spectral patterns as compared with classic mu/beta rhythms. Decoding results further indicate that these new features (91% can detect finger movements much better than classic mu/beta rhythms (75.6%. More importantly, these new features reveal discriminative information about movements of different fingers (fine body-part movements, which is not available in classic mu/beta rhythms. The capability in decoding fingers (and hand gestures in the future from EEG will contribute significantly to the development of noninvasive brain computer interface (BCI and neuroprosthesis with intuitive and flexible controls.
Detection of directivity in seismic site response from microtremor spectral analysis
V. Del Gaudio
2008-07-01
Full Text Available Recent observations have shown that slope response to seismic shaking can be characterised by directional variations of a factor of 2–3 or larger, with maxima oriented along local topography features (e.g. maximum slope direction. This phenomenon appears influenced by slope material properties and has occasionally been detected on landslide-prone slopes, where a down-slope directed amplification could enhance susceptibility to seismically-induced landsliding. The exact conditions for the occurrence of directional amplification remain still unclear and the implementation of investigation techniques capable to reveal the presence of such phenomena is desirable. To this purpose we tested the applicability of a method commonly used to evaluate site resonance properties (Horizontal to Vertical Noise Ratio – HVNR or Nakamura's method as reconnaissance technique for the identification of site response directivity. Measurements of the azimuthal variation of H/V spectral ratios (i.e. between horizontal and vertical component of ambient microtremors were conducted in a landslide-prone study area of central Italy where a local accelerometric network had previously provided evidence of directivity phenomena on some slopes. The test results were compared with average H/V spectral ratios obtained for low-to-moderate earthquakes recorded by the accelerometric stations. In general, noise and seismic recordings provided different amplitudes of spectral ratios at similar frequencies, likely because of differences in signal and instrument characteristics. Nevertheless, both kinds of recordings showed that at sites affected by site response directivity major H/V peaks have orientations consistent (within 20°–30° with the direction of maximum shaking energy. Therefore, HVNR appears to be a promising technique for identifying seismic response directivity. Furthermore, in a comparative test conducted on a slope mantled in part by a deep-seated landslide
A Financial Ratio Analysis of For-Profit and Non-Profit Rural Referral Centers
McCue, Michael J.; Nayar, Preethy
2009-01-01
Context: National financial data show that rural referral center (RRC) hospitals have performed well financially. RRC hospitals' median cash flow margin ratio was 10.04% in 2002 and grew to 11.04% in 2004. Purpose: The aim of this study is to compare the ratio analysis of key operational and financial performance measures of for-profit RRCs to…
Spectral analysis of bacanora (agave-derived liquor) by using FT-Raman spectroscopy
Ortega Clavero, Valentin; Weber, Andreas; Schröder, Werner; Curticapean, Dan
2016-04-01
The industry of the agave-derived bacanora, in the northern Mexican state of Sonora, has been growing substantially in recent years. However, this higher demand still lies under the influences of a variety of social, legal, cultural, ecological and economic elements. The governmental institutions of the state have tried to encourage a sustainable development and certain levels of standardization in the production of bacanora by applying different economical and legal strategies. However, a large portion of this alcoholic beverage is still produced in a traditional and rudimentary fashion. Beyond the quality of the beverage, the lack of proper control, by using adequate instrumental methods, might represent a health risk, as in several cases traditional-distilled beverages can contain elevated levels of harmful materials. The present article describes the qualitative spectral analysis of samples of the traditional-produced distilled beverage bacanora in the range from 0 cm-1 to 3500 cm-1 by using a Fourier Transform Raman spectrometer. This particular technique has not been previously explored for the analysis of bacanora, as in the case of other beverages, including tequila. The proposed instrumental arrangement for the spectral analysis has been built by combining conventional hardware parts (Michelson interferometer, photo-diodes, visible laser, etc.) and a set of self-developed evaluation algorithms. The resulting spectral information has been compared to those of pure samples of ethanol and to the spectra from different samples of the alcoholic beverage tequila. The proposed instrumental arrangement can be used the analysis of bacanora.
Hu, Zhi-yu; Zhang, Lei; Ma, Wei-guang; Yan, Xiao-juan; Li, Zhi-xin; Zhang, Yong-zhi; Wang, Le; Dong, Lei; Yin, Wang-bao; Jia, Suo-tang
2012-03-01
Self-designed identifying software for LIBS spectral line was introduced. Being integrated with LabVIEW, the soft ware can smooth spectral lines and pick peaks. The second difference and threshold methods were employed. Characteristic spectrum of several elements matches the NIST database, and realizes automatic spectral line identification and qualitative analysis of the basic composition of sample. This software can analyze spectrum handily and rapidly. It will be a useful tool for LIBS.
Novel Spectral Representations and Sparsity-Driven Algorithms for Shape Modeling and Analysis
Zhong, Ming
In this dissertation, we focus on extending classical spectral shape analysis by incorporating spectral graph wavelets and sparsity-seeking algorithms. Defined with the graph Laplacian eigenbasis, the spectral graph wavelets are localized both in the vertex domain and graph spectral domain, and thus are very effective in describing local geometry. With a rich dictionary of elementary vectors and forcing certain sparsity constraints, a real life signal can often be well approximated by a very sparse coefficient representation. The many successful applications of sparse signal representation in computer vision and image processing inspire us to explore the idea of employing sparse modeling techniques with dictionary of spectral basis to solve various shape modeling problems. Conventional spectral mesh compression uses the eigenfunctions of mesh Laplacian as shape bases, which are highly inefficient in representing local geometry. To ameliorate, we advocate an innovative approach to 3D mesh compression using spectral graph wavelets as dictionary to encode mesh geometry. The spectral graph wavelets are locally defined at individual vertices and can better capture local shape information than Laplacian eigenbasis. The multi-scale SGWs form a redundant dictionary as shape basis, so we formulate the compression of 3D shape as a sparse approximation problem that can be readily handled by greedy pursuit algorithms. Surface inpainting refers to the completion or recovery of missing shape geometry based on the shape information that is currently available. We devise a new surface inpainting algorithm founded upon the theory and techniques of sparse signal recovery. Instead of estimating the missing geometry directly, our novel method is to find this low-dimensional representation which describes the entire original shape. More specifically, we find that, for many shapes, the vertex coordinate function can be well approximated by a very sparse coefficient representation with
Detector level ABI spectral response function: FM4 analysis and comparison for different ABI modules
Efremova, Boryana; Pearlman, Aaron J.; Padula, Frank; Wu, Xiangqian
2016-09-01
A new generation of imaging instruments Advanced Baseline Imager (ABI) is to be launched aboard the Geostationary Operational Environmental Satellites - R Series (GOES-R). Four ABI flight modules (FM) are planned to be launched on GOES-R,S,T,U, the first one in the fall of 2016. Pre-launch testing is on-going for FM3 and FM4. ABI has 16 spectral channels, six in the visible/near infrared (VNIR 0.47 - 2.25 μm), and ten in the thermal infrared (TIR 3.9 - 13.3 μm) spectral regions, to be calibrated on-orbit by observing respectively a solar diffuser and a blackbody. Each channel has hundreds of detectors arranged in columns. Operationally one Analytic Generation of Spectral Response (ANGEN) function will be used to represent the spectral response function (SRF) of all detectors in a band. The Vendor conducted prelaunch end-to-end SRF testing to compare to ANGEN; detector specific SRF data was taken for: i) best detector selected (BDS) mode - for FM 2,3, and 4; and ii) all detectors (column mode) - for four spectral bands in FM3 and FM4. The GOES-R calibration working group (CWG) has independently used the SRF test data for FM2 and FM3 to study the potential impact of detector-to-detector SRF differences on the ABI detected Earth view radiances. In this paper we expand the CWG analysis to include the FM4 SRF test data - the results are in agreement with the Vendor analysis, and show excellent instrument performance and compare the detector-to-detector SRF differences and their potential impact on the detected Earth view radiances for all of the tested ABI modules.
Performance Analysis of Multi Spectral Band Image Compression using Discrete Wavelet Transform
S. S. Ramakrishnan
2012-01-01
Full Text Available Problem statement: Efficient and effective utilization of transmission bandwidth and storage capacity have been a core area of research for remote sensing images. Hence image compression is required for multi-band satellite imagery. In addition, image quality is also an important factor after compression and reconstruction. Approach: In this investigation, the discrete wavelet transform is used to compress the Landsat5 agriculture and forestry image using various wavelets and the spectral signature graph is drawn. Results: The compressed image performance is analyzed using Compression Ratio (CR, Peak Signal to Noise Ratio (PSNR. The compressed image using dmey wavelet is selected based on its Digital Number Minimum (DNmin and Digital Number Maximum (DNmax. Then it is classified using maximum likelihood classification and the accuracy is determined using error matrix, kappa statistics and over all accuracy. Conclusion: Hence the proposed compression technique is well suited to compress the agriculture and forestry multi-band image.
Zhang, Hong-guang; Lu, Jian-gang
2016-02-01
Abstract To overcome the problems of significant difference among samples and nonlinearity between the property and spectra of samples in spectral quantitative analysis, a local regression algorithm is proposed in this paper. In this algorithm, net signal analysis method(NAS) was firstly used to obtain the net analyte signal of the calibration samples and unknown samples, then the Euclidean distance between net analyte signal of the sample and net analyte signal of calibration samples was calculated and utilized as similarity index. According to the defined similarity index, the local calibration sets were individually selected for each unknown sample. Finally, a local PLS regression model was built on each local calibration sets for each unknown sample. The proposed method was applied to a set of near infrared spectra of meat samples. The results demonstrate that the prediction precision and model complexity of the proposed method are superior to global PLS regression method and conventional local regression algorithm based on spectral Euclidean distance.
Anita Gharekhan; Ashok N Oza; M B Sureshkumar; Asima Pradhan; Prasanta K Panigrahi
2010-12-01
Fluorescence characteristics of human breast tissues are investigated through wavelet transform and principal component analysis (PCA). Wavelet transform of polarized fluorescence spectra of human breast tissues is found to localize spectral features that can reliably differentiate different tissue types. The emission range in the visible wavelength regime of 500–700 nm is analysed, with the excitation wavelength at 488 nm using laser as an excitation source, where flavin and porphyrin are some of the active fluorophores. A number of global and local parameters from principal component analysis of both high- and low-pass coefficients extracted in the wavelet domain, capturing spectral variations and subtle changes in the diseased tissues are clearly identifiable.
[Optimizing spectral region in using near-infrared spectroscopy for donkey milk analysis].
Zheng, Li-Min; Zhang, Lu-Da; Guo, Hui-Yuan; Pang, Kun; Zhang, Wen-Juan; Ren, Fa-Zheng
2007-11-01
Donkey milk has aroused more attention in recent years since its nutrition composition shows a higher similarity to human milk than others. Due to the composition difference between cow milk and donkey milk, the present models available for cow milk analysis could not be applied to donkey milk without modifications. A rapid and reliable analysis method is required to measure the nutrition composition of donkey milk. Near infrared spectroscopy is a newly developed method in food industry, but no literature report was found regarding to its application in the analysis of donkey milk. Protein, fat, ash contents and energy value are the major nutrition factors of milk. In the present paper, these factors of donkey milk were investigated by Fourier transform near-infrared (FT-NIR) spectroscopy. The ranges of protein, fat and ash contents, and energy value in donkey milk samples were 1.15%-2.54%, 0.34%-2.67%, 0.28%-0.57% and 355.87-565.17 cal x kg(-1), respectively. The IR spectra ranged f from 3 899.6 to 12 493.4 cm(-1), with a 1 cm(-1) scanning interval. When the principal least square (PLS) regression algorithm is used for spectral regions information extraction, the additional constraint makes the principal components of matrix X to be related with the components of Y which is to be analyzed. Various spectral regions and data pretreatment methods were selected for principal least square (PLS) regression model development. A comparison of the whole and optimized spectral region NIR indicated that the models of selecting optimum spectral region were better than those of the whole spectral region. It was shown that the protein, fat and ash contents, and energy value in donkey milk obtained by chemical methods were well correlated to the respective values predicted by the NIR spectroscopy quantitative analysis model (alpha = 0.05). The RMSEP values were 0.18, 0.117, 0.040 6 and 23.5 respectively, indicating that these predicted values were reliable. These results
Toward compressed DMD: spectral analysis of fluid flows using sub-Nyquist-rate PIV data
Tu, Jonathan H; Kutz, J Nathan; Shang, Jessica K
2014-01-01
Dynamic mode decomposition (DMD) is a powerful and increasingly popular tool for performing spectral analysis of fluid flows. However, it requires data that satisfy the Nyquist-Shannon sampling criterion. In many fluid flow experiments, such data are impossible to capture. We propose a new approach that combines ideas from DMD and compressed sensing. Given a vector-valued signal, we take measurements randomly in time (at a sub-Nyquist rate) and project the data onto a low-dimensional subspace. We then use compressed sensing to identify the dominant frequencies in the signal and their corresponding modes. We demonstrate this method using two examples, analyzing both an artificially constructed test dataset and particle image velocimetry data collected from the flow past a cylinder. In each case, our method correctly identifies the characteristic frequencies and oscillatory modes dominating the signal, proving the proposed method to be a capable tool for spectral analysis using sub-Nyquist-rate sampling.
Localized Spectral Analysis of Fluctuating Power Generation from Solar Energy Systems
Johan Nijs
2007-01-01
Full Text Available Fluctuations in solar irradiance are a serious obstacle for the future large-scale application of photovoltaics. Occurring regularly with the passage of clouds, they can cause unexpected power variations and introduce voltage dips to the power distribution system. This paper proposes the treatment of such fluctuating time series as realizations of a stochastic, locally stationary, wavelet process. Its local spectral density can be estimated from empirical data by means of wavelet periodograms. The wavelet approach allows the analysis of the amplitude of fluctuations per characteristic scale, hence, persistence of the fluctuation. Furthermore, conclusions can be drawn on the frequency of occurrence of fluctuations of different scale. This localized spectral analysis was applied to empirical data of two successive years. The approach is especially useful for network planning and load management of power distribution systems containing a high density of photovoltaic generation units.
Vo, T D; Dwyer, G; Szeto, H H
1986-04-01
A relatively powerful and inexpensive microcomputer-based system for the spectral analysis of the EEG is presented. High resolution and speed is achieved with the use of recently available large-scale integrated circuit technology with enhanced functionality (INTEL Math co-processors 8087) which can perform transcendental functions rapidly. The versatility of the system is achieved with a hardware organization that has distributed data acquisition capability performed by the use of a microprocessor-based analog to digital converter with large resident memory (Cyborg ISAAC-2000). Compiled BASIC programs and assembly language subroutines perform on-line or off-line the fast Fourier transform and spectral analysis of the EEG which is stored as soft as well as hard copy. Some results obtained from test application of the entire system in animal studies are presented.
Sex ratio and time to pregnancy: analysis of four large European population surveys
Joffe, Mike; Bennett, James; Best, Nicky
2007-01-01
To test whether the secondary sex ratio (proportion of male births) is associated with time to pregnancy, a marker of fertility. Design Analysis of four large population surveys. Setting Denmark and the United Kingdom. Participants 49 506 pregnancies.......To test whether the secondary sex ratio (proportion of male births) is associated with time to pregnancy, a marker of fertility. Design Analysis of four large population surveys. Setting Denmark and the United Kingdom. Participants 49 506 pregnancies....
Spectral decomposition in advection-diffusion analysis by finite element methods
Nickell, R.E.; Gartling, D.K.; Strang, G.
1978-08-11
In a recent study of the convergence properties of finite element methods in nonlinear fluid mechanics, an indirect approach was taken. A two-dimensional example with a known exact solution was chosen as the vehicle for the study, and various mesh refinements were tested in an attempt to extract information on the effect of the local Reynolds number. However, more direct approaches are usually preferred. In this study one such direct approach is followed, based upon the spectral decomposition of the solution operator. Spectral decomposition is widely employed as a solution technique for linear structural dynamics problems and can be applied readily to linear, transient heat transfer analysis; in this case, the extension to nonlinear problems is of interest. It was shown previously that spectral techniques were applicable to stiff systems of rate equations, while recent studies of geometrically and materially nonlinear structural dynamics have demonstrated the increased information content of the numerical results. The use of spectral decomposition in nonlinear problems of heat and mass transfer would be expected to yield equally increased flow of information to the analyst, and this information could include a quantitative comparison of various solution strategies, meshes, and element hierarchies.
Preussler, Stefan; Schneider, Thomas
2015-10-05
Spectral analysis is essential for measuring and monitoring advanced optical communication systems and the characterization of active and passive devices like amplifiers, filters and especially frequency combs. Conventional devices have a limited resolution or tuning range. Therefore, the true spectral shape of the signal remains hidden. In this work, a small part of the signal under test is preselected with help of the polarization pulling effect of stimulated Brillouin scattering where all unwanted spectral components are suppressed. Subsequently, this part is analyzed more deeply through heterodyne detection. Thereby, the local oscillator is generated from a narrow linewidth fiber laser which acts also as pump wave for Brillouin scattering. By scanning the pump wave together with the local oscillator through the signal spectrum, the whole signal is measured. The method is tunable over a broad wavelength range, is not affected by unwanted mixing products and utilizes a conventional narrow bandwidth photo diode. First proof of concept experiments show the measurement of the power spectral density function with a resolution in the attometer or lower kilohertz range at 1550 nm.
Weeds: a CLASS extension for the analysis of millimeter and sub-millimeter spectral surveys
Maret, S; Pety, J; Bardeau, S; Reynier, E
2010-01-01
The advent of large instantaneous bandwidth receivers and high spectral resolution spectrometers on (sub-)millimeter telescopes has opened up the possibilities for unbiased spectral surveys. Because of the large amount of data they contain, any analysis of these surveys requires dedicated software tools. Here we present an extension of the widely used CLASS software that we developed to that purpose. This extension, named Weeds, allows for searches in atomic and molecular lines databases (e.g. JPL or CDMS) that may be accessed over the internet using a virtual observatory (VO) compliant protocol. The package permits a quick navigation across a spectral survey to search for lines of a given species. Weeds is also capable of modeling a spectrum, as often needed for line identification. We expect that Weeds will be useful for analyzing and interpreting the spectral surveys that will be done with the HIFI instrument on board Herschel, but also observations carried-out with ground based millimeter and sub-millimet...
Spectral variability analysis of an XMM-Newton observation of Ark 564
Brinkmann, W; Raeth, C
2007-01-01
We present a spectral variability analysis of the X-ray emission of the Narrow Line Seyfert 1 galaxy Ark 564 using the data from a ~100 ks XMM-Newton observation. Taking advantage of the high sensitivity of this long observation and the simple spectral shape of Ark 564, we determine accurately the spectral variability patterns in the source. We use standard cross-correlation methods to investigate the correlations between the soft and hard energy band light curves. We also generated 200 energy spectra from data stretches of 500 s duration each and fitted each one of them with a power law plus a bremsstrahlung component (for the soft excess) and we investigated the correlations between the various best fit model parameter values. The ``power law plus bremsstrahlung'' model describes the spectrum well at all times. The iron line and the absorption features, which are found in the time-averaged spectrum of the source are too weak to effect the results of the time resolved spectral fits. We find that the power la...
Z. Pashazadeh Atabakan
2013-01-01
Full Text Available Spectral homotopy analysis method (SHAM as a modification of homotopy analysis method (HAM is applied to obtain solution of high-order nonlinear Fredholm integro-differential problems. The existence and uniqueness of the solution and convergence of the proposed method are proved. Some examples are given to approve the efficiency and the accuracy of the proposed method. The SHAM results show that the proposed approach is quite reasonable when compared to homotopy analysis method, Lagrange interpolation solutions, and exact solutions.
Spectral analysis of CFB data: Predictive models of Circulating Fluidized Bed combustors
Gamwo, I.K.; Miller, A.; Gidaspow, D.
1992-04-01
The overall objective of this investigation is to develop experimentally verified models for circulating fluidized bed (CFB) combustors. Spectral analysis of CFB data obtained at Illinois Institute of Technology shows that the frequencies of pressure oscillations are less than 0.1 Hertz and that they increase with solids volume fraction to the usual value of one Hertz obtained in bubbling beds. These data are consistent with the kinetic theory interpretation of density wave propagation.
High Dynamic Range Spectral Analysis in the kHz Band
Boccardi, A
2009-01-01
Many beam instrumentation signals of large circular accelerators are in the kHz range and can thus be digitised with powerful high resolution ADCs. A particularly large dynamic range can be achieved if the signals are analysed in the frequency domain. This report presents a system employing audio ADCs and FPGA-based spectral analysis, initially developed for tune measurement applications. Technical choices allowing frequency domain dynamic ranges beyond 140 dB are summarised.
Tibau, Elisenda; Valencia, Miguel; Soriano, Jordi
2013-01-01
Neuronal networks in vitro are prominent systems to study the development of connections in living neuronal networks and the interplay between connectivity, activity and function. These cultured networks show a rich spontaneous activity that evolves concurrently with the connectivity of the underlying network. In this work we monitor the development of neuronal cultures, and record their activity using calcium fluorescence imaging. We use spectral analysis to characterize global dynamical and structural traits of the neuronal cultures. We first observe that the power spectrum can be used as a signature of the state of the network, for instance when inhibition is active or silent, as well as a measure of the network's connectivity strength. Second, the power spectrum identifies prominent developmental changes in the network such as GABAA switch. And third, the analysis of the spatial distribution of the spectral density, in experiments with a controlled disintegration of the network through CNQX, an AMPA-glutamate receptor antagonist in excitatory neurons, reveals the existence of communities of strongly connected, highly active neurons that display synchronous oscillations. Our work illustrates the interest of spectral analysis for the study of in vitro networks, and its potential use as a network-state indicator, for instance to compare healthy and diseased neuronal networks.
Elisenda eTibau
2013-12-01
Full Text Available Neuronal networks in vitro are prominent systems to study the development of connections in living neuronal networks and the interplay between connectivity, activity and function. These cultured networks show a rich spontaneous activity that evolves concurrently with the connectivity of the underlying network. In this work we monitor the development of neuronal cultures, and record their activity using calcium fluorescence imaging. We use spectral analysis to characterize global dynamical and structural traits of the neuronal cultures. We first observe that the power spectrum can be used as a signature of the state of the network, for instance when inhibition is active or silent, as well as a measure of the network's connectivity strength. Second, the power spectrum identifies prominent developmental changes in the network such as GABAA switch. And third, the analysis of the spatial distribution of the spectral density, in experiments with a controlled disintegration of the network through CNQX, an AMPA-glutamate receptor antagonist in excitatory neurons, reveals the existence of communities of strongly connected, highly active neurons that display synchronous oscillations. Our work illustrates the interest of spectral analysis for the study of in vitro networks, and its potential use as a network-state indicator, for instance to compare healthy and diseased neuronal networks.
Qian Wang
2016-01-01
Full Text Available Spectroscopy is an efficient and widely used quantitative analysis method. In this paper, a spectral quantitative analysis model with combining wavelength selection and topology structure optimization is proposed. For the proposed method, backpropagation neural network is adopted for building the component prediction model, and the simultaneousness optimization of the wavelength selection and the topology structure of neural network is realized by nonlinear adaptive evolutionary programming (NAEP. The hybrid chromosome in binary scheme of NAEP has three parts. The first part represents the topology structure of neural network, the second part represents the selection of wavelengths in the spectral data, and the third part represents the parameters of mutation of NAEP. Two real flue gas datasets are used in the experiments. In order to present the effectiveness of the methods, the partial least squares with full spectrum, the partial least squares combined with genetic algorithm, the uninformative variable elimination method, the backpropagation neural network with full spectrum, the backpropagation neural network combined with genetic algorithm, and the proposed method are performed for building the component prediction model. Experimental results verify that the proposed method has the ability to predict more accurately and robustly as a practical spectral analysis tool.
Chen, Da; Grant, Edward
2012-11-01
When paired with high-powered chemometric analysis, spectrometric methods offer great promise for the high-throughput analysis of complex systems. Effective classification or quantification often relies on signal preprocessing to reduce spectral interference and optimize the apparent performance of a calibration model. However, less frequently addressed by systematic research is the affect of preprocessing on the statistical accuracy of a calibration result. The present work demonstrates the effectiveness of two criteria for validating the performance of signal preprocessing in multivariate models in the important dimensions of bias and precision. To assess the extent of bias, we explore the applicability of the elliptic joint confidence region (EJCR) test and devise a new means to evaluate precision by a bias-corrected root mean square error of prediction. We show how these criteria can effectively gauge the success of signal pretreatments in suppressing spectral interference while providing a straightforward means to determine the optimal level of model complexity. This methodology offers a graphical diagnostic by which to visualize the consequences of pretreatment on complex multivariate models, enabling optimization with greater confidence. To demonstrate the application of the EJCR criterion in this context, we evaluate the validity of representative calibration models using standard pretreatment strategies on three spectral data sets. The results indicate that the proposed methodology facilitates the reliable optimization of a well-validated calibration model, thus improving the capability of spectrophotometric analysis.
Suzuki, Daisuke; Esaka, Fumitaka; Miyamoto, Yutaka; Magara, Masaaki
2015-02-01
Uranium and plutonium isotope ratios in individual uranium-plutonium (U-Pu) mixed particles with various U/Pu atomic ratios were analyzed without prior chemical separation by thermal ionization mass spectrometry (TIMS). Prior to measurement, micron-sized particles with U/Pu ratios of 1, 5, 10, 18, and 70 were produced from uranium and plutonium certified reference materials. In the TIMS analysis, the peaks of americium, plutonium, and uranium ion signals were successfully separated by continuously increasing the evaporation filament current. Consequently, the uranium and plutonium isotope ratios, except the (238)Pu/(239)Pu ratio, were successfully determined for the particles at all U/Pu ratios. This indicates that TIMS direct analysis allows for the measurement of individual U-Pu mixed particles without prior chemical separation.
Spectral analysis for the mineralogical characterization of planosols in NE Brazil
Costa, Diego; Souza, Deorgia; Rocha, Washington
2016-04-01
This paper aims to conduct a spectral characterization in two soil profiles located in the northeast of Brazil proposing relations between the pedogenetic evolution and the environmental settings generated from the characteristics of Planosols analyzed and the presence of minerals identified by spectral pattern obtained in a laboratory. The methodological procedures were divided into the characterization of the study area, theoretical framework, field work with sampling, sample preparation, measurement in the laboratory, processing of spectral data, analysis and interpretation of results and a vegetation index calculation for aid in the environmental characterization. It is possible to see that: i) both profiles have similar spectral characterized patterns; ii) the horizons A and E show higher reflectance compared with B and C; iii) Minerals 2: 1 and 1: 1, such as montmorillonite and kaolinite can be identified; iv) Planosols are fragile to erosion. In both profiles, the C horizon less weathered and B horizon iluvial show intense absorption bands at 1400nm, 1900nm and 2200nm. These absorption bands indicate the existence of mineralogy 2: 1 on the horizons of the soils analyzed. In both profiles were found small peaks absorption in 2265nm, corresponding to gibbsite. The occurrence of this type of mineral is more common in highly weathered soils or old surfaces of erosion, which is reflected in small intensities of absorption observed in this analysis since these are of little-weathered soils of the Brazilian semiarid region. Spectral analysis and morphology described in the two profiles show difficulties for the growth of vegetation, which is consistent with NDVI values found, ranging from -0.32 to 0.61with a predominance of 0.19. These factors lead to the intensification of erosion. Erosion is characterized as one of the main indicators of environmental degradation, causing loss of important elements of the soil, which creates consequently a reduction in fertility
Nguyen Dinh, Duong
2016-06-01
Recently USGS released provisional Landsat 8 Surface Reflectance product, which allows conducting land cover mapping over large composed of number of image scenes without necessity of atmospheric correction. In this study, the authors present a new concept for automated classification of land cover. This concept is based on spectral patterns analysis of reflected bands and can be automated using predefined classification rule set constituted of spectral pattern shape, total reflected radiance index (TRRI) and ratios of spectral bands. Given a pixel vector B6 = {b1,b2,b3,b4,b5,b6} where b1, b2,...,b6 denote bands 2, 3, ...,7 of OLI sensor respectively. By using the pixel vector B6 we can construct spectral reflectance curve. Each spectral curve is featured by a shape, which can be described in simplified form of an analogue pattern, which is consisted of 15 digits of 0, 1 and 2 showing mutual relative position of spectral vertices. Value of comparison between band i and j is 2 if bj > bi, 1 if bj = bi and 0 if bj < bi. Simplified spectral pattern is defined by 15 digits as m1,2m1,3m1,4m1,5m1,6m2,3m2,4m2,5m2,6m3,4m3,5m3,6m4,5m4,6m5,6 where mi,j is result of comparison of reflectance between bi and bj and has values of 0, 1 and 2. After construction of SSP for each pixel in the input image, the original image will be decomposed to component images, which contain pixels with the same SRCS pattern. The decomposition can be written analytically by equation A = Σnk=1Ck where A stands for original image with 6 spectral bands, n is number of component images decomposed from A and Ck is component image. For this study, we use Landsat 8 OLI reflectance image LC81270452013352LGN00 and LC81270452015182LGN00. For the decomposition, we use only six reflective bands. Each land cover class is defined by SSP code, threshold values for TRRI and band ratios. Automated classification of land cover was realized with 8 classes: forest, shrub, grass, water, wetland, develop land, barren
An Excel-based implementation of the spectral method of action potential alternans analysis.
Pearman, Charles M
2014-12-01
Action potential (AP) alternans has been well established as a mechanism of arrhythmogenesis and sudden cardiac death. Proper interpretation of AP alternans requires a robust method of alternans quantification. Traditional methods of alternans analysis neglect higher order periodicities that may have greater pro-arrhythmic potential than classical 2:1 alternans. The spectral method of alternans analysis, already widely used in the related study of microvolt T-wave alternans, has also been used to study AP alternans. Software to meet the specific needs of AP alternans analysis is not currently available in the public domain. An AP analysis tool is implemented here, written in Visual Basic for Applications and using Microsoft Excel as a shell. This performs a sophisticated analysis of alternans behavior allowing reliable distinction of alternans from random fluctuations, quantification of alternans magnitude, and identification of which phases of the AP are most affected. In addition, the spectral method has been adapted to allow detection and quantification of higher order regular oscillations. Analysis of action potential morphology is also performed. A simple user interface enables easy import, analysis, and export of collated results.
Financial Ratio Analysis: the Development of a Dedicated Management Information System
Voicu-Dan Dragomir
2007-01-01
Full Text Available This paper disseminates the results of the development process for a financial analysis information system. The system has been subject to conceptual design using the Unified Modeling Language (UML and has been implemented in object-oriented manner using the Visual Basic .NET 2003 programming language. The classic financial analysis literature is focused on the chain-substitution method of computing the prior-year to current-year variation of linked financial ratios. We have applied this technique on the DuPont System of analysis concerning the Return on Equity ratio, by designing several structural UML diagrams depicting the breakdown and analysis of each financial ratio involved. The resulting computer application offers a flexible approach to the analytical tools: the user is required to introduce the raw data and the system provides both table-style and charted information on the output of computation. User-friendliness is also a key feature of this particular financial analysis application.
Financial Ratio Analysis: the Development of a Dedicated Management Information System
Voicu-Dan Dragomir
2007-01-01
Full Text Available This paper disseminates the results of the development process for a financial analysis information system. The system has been subject to conceptual design using the Unified Modeling Language (UML and has been implemented in object-oriented manner using the Visual Basic .NET 2003 programming language. The classic financial analysis literature is focused on the chain-substitution method of computing the prior-year to current-year variation of linked financial ratios. We have applied this technique on the DuPont System of analysis concerning the Return on Equity ratio, by designing several structural UML diagrams depicting the breakdown and analysis of each financial ratio involved. The resulting computer application offers a flexible approach to the analytical tools: the user is required to introduce the raw data and the system provides both table-style and charted information on the output of computation. User-friendliness is also a key feature of this particular financial analysis application.
Toadere, Florin
2015-02-01
A software that comparatively analysis the spectral functionality of the optical part of the human eye and of the optical image acquisition system of the digital camera, is presented. Comparisons are done using demonstrative images which present the spectral color transformations of an image that is considered the test object. To perform the simulations are presented the spectral models and are computed their effects on the colors of the spectral image, during the propagation of the D48 sun light through the eye and the optics of the digital camera. The simulations are made using a spectral image processing algorithm which converts the spectral image into XYZ color space, CIE CAM02 color appearance model and then into RGB color space.
Schneider, P.; Roberts, D. A.
2007-12-01
The Fire Potential Index (FPI) is currently the only operationally used wildfire susceptibility index in the United States that incorporates remote sensing data in addition to meteorological information. Its remote sensing component utilizes relative greenness derived from a NDVI time series as a proxy for computing the ratio of live to dead vegetation. This study investigates the potential of Multiple Endmember Spectral Mixture Analysis (MESMA) as a more direct and physically reasonable way of computing the live ratio and applying it for the computation of the FPI. A time series of 16-day reflectance composites of Moderate Resolution Imaging Spectroradiometer (MODIS) data was used to perform the analysis. Endmember selection for green vegetation (GV), non- photosynthetic vegetation (NPV) and soil was performed in two stages. First, a subset of suitable endmembers was selected from an extensive library of reference and image spectra for each class using Endmember Average Root Mean Square Error (EAR), Minimum Average Spectral Angle (MASA) and a count-based technique. Second, the most appropriate endmembers for the specific data set were selected from the subset by running a series of 2-endmember models on representative images and choosing the ones that modeled the majority of pixels. The final set of endmembers was used for running MESMA on southern California MODIS composites from 2000 to 2006. 3- and 4-endmember models were considered. The best model was chosen on a per-pixel basis according to the minimum root mean square error of the models at each level of complexity. Endmember fractions were normalized by the shade endmember to generate realistic fractions of GV and NPV. In order to validate the MESMA-derived GV fractions they were compared against live ratio estimates from RG. A significant spatial and temporal relationship between both measures was found, indicating that GV fraction has the potential to substitute RG in computing the FPI. To further test
De, Anupam; Bandyopadhyay, Gautam; Chakraborty, B. N.
2010-10-01
Financial ratio analysis is an important and commonly used tool in analyzing financial health of a firm. Quite a large number of financial ratios, which can be categorized in different groups, are used for this analysis. However, to reduce number of ratios to be used for financial analysis and regrouping them into different groups on basis of empirical evidence, Factor Analysis technique is being used successfully by different researches during the last three decades. In this study Factor Analysis has been applied over audited financial data of Indian cement companies for a period of 10 years. The sample companies are listed on the Stock Exchange India (BSE and NSE). Factor Analysis, conducted over 44 variables (financial ratios) grouped in 7 categories, resulted in 11 underlying categories (factors). Each factor is named in an appropriate manner considering the factor loads and constituent variables (ratios). Representative ratios are identified for each such factor. To validate the results of Factor Analysis and to reach final conclusion regarding the representative ratios, Cluster Analysis had been performed.
Zhang, H X
2008-01-01
An innovative approach for total maximum daily load (TMDL) allocation and implementation is the watershed-based pollutant trading. Given the inherent scientific uncertainty for the tradeoffs between point and nonpoint sources, setting of trading ratios can be a contentious issue and was already listed as an obstacle by several pollutant trading programs. One of the fundamental reasons that a trading ratio is often set higher (e.g. greater than 2) is to allow for uncertainty in the level of control needed to attain water quality standards, and to provide a buffer in case traded reductions are less effective than expected. However, most of the available studies did not provide an approach to explicitly address the determination of trading ratio. Uncertainty analysis has rarely been linked to determination of trading ratio.This paper presents a practical methodology in estimating "equivalent trading ratio (ETR)" and links uncertainty analysis with trading ratio determination from TMDL allocation process. Determination of ETR can provide a preliminary evaluation of "tradeoffs" between various combination of point and nonpoint source control strategies on ambient water quality improvement. A greater portion of NPS load reduction in overall TMDL load reduction generally correlates with greater uncertainty and thus requires greater trading ratio. The rigorous quantification of trading ratio will enhance the scientific basis and thus public perception for more informed decision in overall watershed-based pollutant trading program.
Vigil-Galan, O.; Sastre-Hernandez, J.; Contreras-Puente, G.; Tufino-Velazquez, M. [Escuela Superior de Fisica y Matematicas, Instituto Politecnico Nacional, 07738 Mexico D. F. (Mexico); Arias-Carbajal, A. [Facultad de Quimica, IMRE, Universidad de La Habana, 10400 La Habana (Cuba); Mendoza-Perez, R. [Universidad Autonoma de la Ciudad de Mexico, 09970 Mexico, D. F. (Mexico); Santana, G. [Instituto de Investigacion en Materiales, UNAM, 04510 Mexico, D. F. (Mexico); Morales-Acevedo, A. [Departamento de Ingenieria Electrica, CINVESTAV-IPN, 07360 Mexico, D. F. (Mexico)
2006-09-22
In this work, the influence of the variation of chemical bath thiourea concentration in the solution for depositing CdS layers upon the spectral response of chemical bath deposition (CBD)-CdS/CdTe solar cells is studied. Although changes in the short and long wavelength range for the spectral response of the cells were observed in dependence of the thiourea concentration, no significant changes were observed in the diffusion length of minority carriers in the CdTe layer, as determined from the constant photocurrent method, when the thiourea concentration is increased in the CdS deposition solution. (author)
Moerdijk-Poortvliet, T.C.W.; Schierbeek, H.; Houtekamer, M.; van Engeland, T.; Derrien, D.; Stal, L.J.; Boschker, H.T.S.
2015-01-01
We compared gas chromatography/isotope ratio mass spectrometry (GC/IRMS) and liquid chromatography/isotope ratio mass spectrometry (LC/IRMS) for the measurement of d13C values in carbohydrates. Contrary to GC/IRMS, no derivatisation is needed for LC/IRMS analysis of carbohydrates. Hence, although
TOF plotter—a program to perform routine analysis time-of-flight mass spectral data
Knippel, Brad C.; Padgett, Clifford W.; Marcus, R. Kenneth
2004-03-01
The main article discusses the operation and application of the program to mass spectral data files. This laboratory has recently reported the construction and characterization of a linear time-of-flight mass spectrometer (ToF-MS) utilizing a radio frequency glow discharge ionization source. Data acquisition and analysis was performed using a digital oscilloscope and Microsoft Excel, respectively. Presently, no software package is available that is specifically designed for time-of-flight mass spectral analysis that is not instrument dependent. While spreadsheet applications such as Excel offer tremendous utility, they can be cumbersome when repeatedly performing tasks which are too complex or too user intensive for macros to be viable. To address this situation and make data analysis a faster, simpler task, our laboratory has developed a Microsoft Windows-based software program coded in Microsoft Visual Basic. This program enables the user to rapidly perform routine data analysis tasks such as mass calibration, plotting and smoothing on x- y data sets. In addition to a suite of tools for data analysis, a number of calculators are built into the software to simplify routine calculations pertaining to linear ToF-MS. These include mass resolution, ion kinetic energy and single peak identification calculators. A detailed description of the software and its associated functions is presented followed by a characterization of its performance in the analysis of several representative ToF-MS spectra obtained from different GD-ToF-MS systems.
Yan Zhou
2013-01-01
Full Text Available We propose an augmented classical least squares (ACLS calibration method for quantitative Raman spectral analysis against component information loss. The Raman spectral signals with low analyte concentration correlations were selected and used as the substitutes for unknown quantitative component information during the CLS calibration procedure. The number of selected signals was determined by using the leave-one-out root-mean-square error of cross-validation (RMSECV curve. An ACLS model was built based on the augmented concentration matrix and the reference spectral signal matrix. The proposed method was compared with partial least squares (PLS and principal component regression (PCR using one example: a data set recorded from an experiment of analyte concentration determination using Raman spectroscopy. A 2-fold cross-validation with Venetian blinds strategy was exploited to evaluate the predictive power of the proposed method. The one-way variance analysis (ANOVA was used to access the predictive power difference between the proposed method and existing methods. Results indicated that the proposed method is effective at increasing the robust predictive power of traditional CLS model against component information loss and its predictive power is comparable to that of PLS or PCR.
The Swift X-ray Telescope Cluster Survey III: X-ray spectral analysis
Tozzi, P; Tundo, E; Liu, T; Rosati, P; Borgani, S; Tagliaferri, G; Campana, S; Fugazza, D; D'Avanzo, P
2014-01-01
(Abridged) We present a spectral analysis of a new, flux-limited sample of 72 X-ray selected clusters of galaxies identified with the X-ray Telescope (XRT) on board the Swift satellite down to a flux limit of ~10-14 erg/s/cm2 (SWXCS, Tundo et al. 2012). We carry out a detailed X-ray spectral analysis with the twofold aim of measuring redshifts and characterizing the properties of the Intra-Cluster Medium (ICM). Optical counterparts and spectroscopic or photometric redshifts are obtained with a cross-correlation with NED. Additional photometric redshifts are computed with a dedicated follow-up program with the TNG and a cross-correlation with the SDSS. We also detect the iron emission lines in 35% of the sample, and hence obtain a robust measure of the X-ray redshift zX. We use zX whenever the optical redshift is not available. Finally, for all the sources with measured redshift, background-subtracted spectra are fitted with a mekal model. We perform extensive spectral simulations to derive an empirical formul...
Identification of mineral compositions in some renal calculi by FT Raman and IR spectral analysis
Tonannavar, J.; Deshpande, Gouri; Yenagi, Jayashree; Patil, Siddanagouda B.; Patil, Nikhil A.; Mulimani, B. G.
2016-02-01
We present in this paper accurate and reliable Raman and IR spectral identification of mineral constituents in nine samples of renal calculi (kidney stones) removed from patients suffering from nephrolithiasis. The identified mineral components include Calcium Oxalate Monohydrate (COM, whewellite), Calcium Oxalate Dihydrate (COD, weddellite), Magnesium Ammonium Phosphate Hexahydrate (MAPH, struvite), Calcium Hydrogen Phosphate Dihydrate (CHPD, brushite), Pentacalcium Hydroxy Triphosphate (PCHT, hydroxyapatite) and Uric Acid (UA). The identification is based on a satisfactory assignment of all the observed IR and Raman bands (3500-400 cm- 1) to chemical functional groups of mineral components in the samples, aided by spectral analysis of pure materials of COM, MAPH, CHPD and UA. It is found that the eight samples are composed of COM as the common component, the other mineral species as common components are: MAPH in five samples, PCHT in three samples, COD in three samples, UA in three samples and CHPD in two samples. One sample is wholly composed of UA as a single component; this inference is supported by the good agreement between ab initio density functional theoretical spectra and experimental spectral measurements of both sample and pure material. A combined application of Raman and IR techniques has shown that, where the IR is ambiguous, the Raman analysis can differentiate COD from COM and PCHT from MAPH.
Tsuchiya, Komei; Kogure, Shinichi
2012-09-01
Kindling is one of the popular animal models of temporal lobe epilepsy. In the present study following the previous results obtained using unilateral hippocampal kindling (UK), we performed spectral analysis of bilateral or alternate-site kindling-induced afterdischarges (ADs) in the rabbit hippocampi. Eight and ten adult rabbits were used for bilateral kindling (BK) and alternate-site kindling (AK), respectively. Kindling stimuli consisted of a train of biphasic pulses (1ms duration each) of 50Hz for 1s, with suprathreshold intensity for AD. The stimulations were applied simultaneously to the bilateral hippocampi in the BK and were delivered to the right and left hippocampus once every 24h in the AK. Motor responses were classified into five stages according to the conventional criteria. All animals in BK as well as AK developed stage 5 convulsions. This contrasts to the result of UK (kindled: 50%; incomplete: 50%). We normalized power spectral density (PSD) and monitored the changes in the proportion of lower frequency band component (LFB: 0-9Hz) and the higher frequency band (HFB: 12-30Hz). BK animals showed a significantly large decrement (0.5 times, pkindling progression. Very strong positive correlations were found in both kindling animals. Chronological spectral analysis of seizure discharges, resulting in a pattern of LFB decrement accompanied by HFB increment, is a convenient tool to investigate epileptic disorders and diagnose epileptic states.
Uterine EMG spectral analysis and relationship to mechanical activity in pregnant monkeys.
Mansour, S; Devedeux, D; Germain, G; Marque, C; Duchêne, J
1996-03-01
The objective is to analyse internal and external recordings of uterine EMG in order to reveal common features and to assess the relationship between electrical activity and intra-uterine pressure modification. Three monkeys participated in the study, one as a reference and the others for data. EMGs are recorded simultaneously, internally by unipolar wire electrodes and externally by bipolar Ag/AgCl electrodes. Intra-uterine pressure is recorded as a mechanical index. Except for delay measurements, parameters are derived from spectral analysis and relationships between recordings are assessed by studying the coherence. Spectral analysis exhibits two basic activities in the analysed frequency band, and frequency limits are defined as relevant parameters for electrical activity description. Parameter values do not depend on the internal electrode location. Internal and external EMGs present a similar spectral shape, despite differences in electrode configuration and tissue filtering. It is deduced that external uterine EMG is a good image of the genuine uterine electrical activity. To some extent, it can be related to an average cellular electrical activity.
XMM-Newton and Swift observations of WZ Sge: spectral and timing analysis
Nucita, A A; De Paolis, F; Mukai, K; Ingrosso, G; Maiolo, B M T
2014-01-01
WZ Sagittae is the prototype object of a subclass of dwarf novae, with rare and long (super)outbursts, in which a white dwarf primary accretes matter from a low mass companion. High-energy observations offer the possibility of a better understanding of the disk-accretion mechanism in WZ Sge-like binaries. We used archival XMM-Newton and Swift data to characterize the X-ray spectral and temporal properties of WZ Sge in quiescence. We performed a detailed timing analysis of the simultaneous X-ray and UV light curves obtained with the EPIC and OM instruments on board XMM-Newton in 2003. We employed several techniques in this study, including a correlation study between the two curves. We also performed an X-ray spectral analysis using the EPIC data, as well as Swift/XRT data obtained in 2011. We find that the X-ray intensity is clearly modulated at a period of about 28.96 s, confirming previously published preliminary results. We find that the X-ray spectral shape of WZ Sge remains practically unchanged between ...
Assessment of Infrared Sounder Radiometric Noise from Analysis of Spectral Residuals
Dufour, E.; Klonecki, A.; Standfuss, C.; Tournier, B.; Serio, C.; Masiello, G.; Tjemkes, S.; Stuhlmann, R.
2016-08-01
For the preparation and performance monitoring of the future generation of hyperspectral InfraRed sounders dedicated to the precise vertical profiling of the atmospheric state, such as the Meteosat Third Generation hyperspectral InfraRed Sounder, a reliable assessment of the instrument radiometric error covariance matrix is needed.Ideally, an inflight estimation of the radiometrric noise is recommended as certain sources of noise can be driven by the spectral signature of the observed Earth/ atmosphere radiance. Also, unknown correlated noise sources, generally related to incomplete knowledge of the instrument state, can be present, so a caracterisation of the noise spectral correlation is also neeed.A methodology, relying on the analysis of post-retreival spectral residuals, is designed and implemented to derive in-flight the covariance matrix on the basis of Earth scenes measurements. This methodology is successfully demonstrated using IASI observations as MTG-IRS proxy data and made it possible to highlight anticipated correlation structures explained by apodization and micro-vibration effects (ghost). This analysis is corroborated by a parallel estimation based on an IASI black body measurement dataset and the results of an independent micro-vibration model.
Insights on the Bayesian spectral density method for operational modal analysis
Au, Siu-Kui
2016-01-01
This paper presents a study on the Bayesian spectral density method for operational modal analysis. The method makes Bayesian inference of the modal properties by using the sample power spectral density (PSD) matrix averaged over independent sets of ambient data. In the typical case with a single set of data, it is divided into non-overlapping segments and they are assumed to be independent. This study is motivated by a recent paper that reveals a mathematical equivalence of the method with the Bayesian FFT method. The latter does not require averaging concepts or the independent segment assumption. This study shows that the equivalence does not hold in reality because the theoretical long data asymptotic distribution of the PSD matrix may not be valid. A single time history can be considered long for the Bayesian FFT method but not necessarily for the Bayesian PSD method, depending on the number of segments.
Spectral analysis of the sdO standard star Feige 34
Latour, M; Green, E M; Fontaine, G
2016-01-01
We present our current work on the spectral analysis of the hot sdO star Feige 34. We combine high S/N optical spectra and fully-blanketed non-LTE model atmospheres to derive its fundamental parameters (Teff, log g) and helium abundance. Our best fits indicate Teff =63 000 K, log g=6.0 and log N(He)/N(H)=-1.8. We also use available ultraviolet spectra (IUE and FUSE) to measure metal abundances. We find the star to be enriched in iron and nickel by a factor of ten with respect to the solar values, while lighter elements have subsolar abundances. The FUSE spectrum suggests that the spectral lines could be broadened by rotation.
A Spectral Multiscale Method for Wave Propagation Analysis: Atomistic-Continuum Coupled Simulation
Patra, Amit K; Ganguli, Ranjan
2014-01-01
In this paper, we present a new multiscale method which is capable of coupling atomistic and continuum domains for high frequency wave propagation analysis. The problem of non-physical wave reflection, which occurs due to the change in system description across the interface between two scales, can be satisfactorily overcome by the proposed method. We propose an efficient spectral domain decomposition of the total fine scale displacement along with a potent macroscale equation in the Laplace domain to eliminate the spurious interfacial reflection. We use Laplace transform based spectral finite element method to model the macroscale, which provides the optimum approximations for required dynamic responses of the outer atoms of the simulated microscale region very accurately. This new method shows excellent agreement between the proposed multiscale model and the full molecular dynamics (MD) results. Numerical experiments of wave propagation in a 1D harmonic lattice, a 1D lattice with Lennard-Jones potential, a ...
Spectral analysis of laser-Doppler perfusion signal measured during thermal test.
Maniewski, R; Leger, P; Lewandowski, P; Liebert, A; Bendayan, P; Boccalon, H; Bajorski, L; Möller, K O
1999-01-01
The method of spectral analysis of laser-Doppler perfusion signal measured during thermal test is proposed. During three 20 min phases with 40, 5, and 40 degrees C of thermal test laser-Doppler perfusion signal was recorded. For each signal phase frequency spectra were calculated using the FFT method. Quantitative parameter Spectral Factor for results evaluation was proposed. In total 94 patients were measured: 69 with Raynaud's phenomenon and 25 normal subjects. Additionally in 18 Raynaud's patients the influence of Nifedipine was studied. Results suggest that proposed parameter is able to differentiate between Raynaud's patients and normal subjects and that is useful for evaluation of Nifedipine effectiveness. However, further studies are needed to improve the method to differentiate between primary and secondary Raynaud's patients.
M.Yakit ONGUN
2007-01-01
In this paper we consider the nonselfadjoint (dissipative) Schr(o)dinger boundary value problem in the limit-circle case with an eigenparameter in the boundary condition. Since the boundary conditions are nonselfadjoint, the approach is based on the use of the maximal dissipative operator,and the spectral analysis of this operator is adequate for the boundary value problem. We construct a selfadjoint dilation of the maximal dissipative operator and its incoming and outgoing spectral representations, which make it possible to determine the scattering matrix of the dilation. We construct a functional model of the maximal dissipative operator and define its characteristic function in terms of solutions of the corresponding Schr(o)dinger equation. Theorems on the completeness of the system of eigenvectors and the associated vectors of the maximal dissipative operator and the Schr(o)dinger boundary value problem are given.