Lawson, J.
1997-03-03
What follows is a description of my analysis. First, the FFT that I use is described on the attached pages. Note that the scaling factor for the forward transform is 1/N. I compute the following rms values: rms(original data) = 64.9463 nm; rms(data*hanning) = 55.7723 nm (before renormalization). The use of the hanning filter is accompanied by a renormalization to insure that the rms value is maintained. I also fit to the curvature of the scan. The data corrected for focus gives the following rms values: rms(corrected data) = 56.8835 nm; rms(corrected data*hanning) = 53.2179 nm (before renormalization). The PSD is shown for various data. The PSD is calculated as: PSD = | FFT(y) | {sup 2} * xl where xl is the length of the x axis, 45.9952. I did find an error in the plot that you were sent. If kx is the frequency axis, i.e., values from (0,Nyquist), then kx(l,Nyquist) is plotted versus PSD(0,Nyquist). This error is corrected in the attached plots. The plot you have appears to be the PSD of the original data with no hanning applied. The removal of the quadratic term appear to have a negligible effect on the PSD. It changes only the first couple of terms (which lie outside of the data valid range). The removal of the center feature has a much stronger effect.
Fourier Analysis of Musical Intervals
NASA Astrophysics Data System (ADS)
LoPresto, Michael C.
2008-11-01
Use of a microphone attached to a computer to capture musical sounds and software to display their waveforms and harmonic spectra has become somewhat commonplace. A recent article in The Physics Teacher aptly demonstrated the use of MacScope2 in just such a manner as a way to teach Fourier analysis.3 A logical continuation of this project is to use MacScope not just to analyze the Fourier composition of musical tones but also musical intervals.
Fourier Analysis of Musical Intervals
ERIC Educational Resources Information Center
LoPresto, Michael C.
2008-01-01
Use of a microphone attached to a computer to capture musical sounds and software to display their waveforms and harmonic spectra has become somewhat commonplace. A recent article in "The Physics Teacher" aptly demonstrated the use of MacScope in just such a manner as a way to teach Fourier analysis. A logical continuation of this project is to…
Fourier analysis of blazar variability
Finke, Justin D.; Becker, Peter A.
2014-08-10
Blazars display strong variability on multiple timescales and in multiple radiation bands. Their variability is often characterized by power spectral densities (PSDs) and time lags plotted as functions of the Fourier frequency. We develop a new theoretical model based on the analysis of the electron transport (continuity) equation, carried out in the Fourier domain. The continuity equation includes electron cooling and escape, and a derivation of the emission properties includes light travel time effects associated with a radiating blob in a relativistic jet. The model successfully reproduces the general shapes of the observed PSDs and predicts specific PSD and time lag behaviors associated with variability in the synchrotron, synchrotron self-Compton, and external Compton emission components, from submillimeter to γ-rays. We discuss applications to BL Lacertae objects and to flat-spectrum radio quasars (FSRQs), where there are hints that some of the predicted features have already been observed. We also find that FSRQs should have steeper γ-ray PSD power-law indices than BL Lac objects at Fourier frequencies ≲ 10{sup –4} Hz, in qualitative agreement with previously reported observations by the Fermi Large Area Telescope.
Ultrasonic Transducers for Fourier Analysis.
ERIC Educational Resources Information Center
Greenslade, Thomas B., Jr.
1995-01-01
Describes an experiment that uses the ultrasonic transducer for demonstrating the Fourier components of waveshapes such as the square and triangular waves produced by laboratory function generators. (JRH)
Fourier analysis and synthesis tomography.
Wagner, Kelvin H.; Sinclair, Michael B.; Feldkuhn, Daniel
2010-05-01
Most far-field optical imaging systems rely on a lens and spatially-resolved detection to probe distinct locations on the object. We describe and demonstrate a novel high-speed wide-field approach to imaging that instead measures the complex spatial Fourier transform of the object by detecting its spatially-integrated response to dynamic acousto-optically synthesized structured illumination. Tomographic filtered backprojection is applied to reconstruct the object in two or three dimensions. This technique decouples depth-of-field and working-distance from resolution, in contrast to conventional imaging, and can be used to image biological and synthetic structures in fluoresced or scattered light employing coherent or broadband illumination. We discuss the electronically programmable transfer function of the optical system and its implications for imaging dynamic processes. Finally, we present for the first time two-dimensional high-resolution image reconstructions demonstrating a three-orders-of-magnitude improvement in depth-of-field over conventional lens-based microscopy.
Nonlinear Fourier analysis with cnoidal waves
Osborne, A.R.
1996-12-31
Fourier analysis is one of the most useful tools to the ocean engineer. The approach allows one to analyze wave data and thereby to describe a dynamical motion in terms of a linear superposition of ordinary sine waves. Furthermore, the Fourier technique allows one to compute the response function of a fixed or floating structure: each sine wave in the wave or force spectrum yields a sine wave in the response spectrum. The counting of fatigue cycles is another area where the predictable oscillations of sine waves yield procedures for the estimation of the fatigue life of structures. The ocean environment, however, is a source of a number of nonlinear effects which must also be included in structure design. Nonlinearities in ocean waves deform the sinusoidal shapes into other kinds of waves such as the Stokes wave, cnoidal wave or solitary wave. A key question is: Does there exist a generalization of linear Fourier analysis which uses nonlinear basis functions rather than the familiar sine waves? Herein addresses the dynamics of nonlinear wave motion in shallow water where the basis functions are cnoidal waves and discuss nonlinear Fourier analysis in terms of a linear superposition of cnoidal waves plus their mutual nonlinear interactions. He gives a number of simple examples of nonlinear Fourier wave motion and then analyzes an actual surface-wave time series obtained on an offshore platform in the Adriatic Sea. Finally, he briefly discusses application of the cnoidal wave spectral approach to the computation of the frequency response function of a floating vessel. The results given herein will prove useful in future engineering studies for the design of fixed, floating and complaint offshore structures.
Fourier analysis of the SOR iteration
NASA Technical Reports Server (NTRS)
Leveque, R. J.; Trefethen, L. N.
1986-01-01
The SOR iteration for solving linear systems of equations depends upon an overrelaxation factor omega. It is shown that for the standard model problem of Poisson's equation on a rectangle, the optimal omega and corresponding convergence rate can be rigorously obtained by Fourier analysis. The trick is to tilt the space-time grid so that the SOR stencil becomes symmetrical. The tilted grid also gives insight into the relation between convergence rates of several variants.
Fourier analysis of quadratic phase interferograms
NASA Astrophysics Data System (ADS)
Muñoz-Maciel, Jesús; Mora-González, Miguel; Casillas-Rodríguez, Francisco J.; Peña-Lecona, Francisco G.
2015-06-01
A phase demodulation method from a single interferogram with a quadratic phase term is developed. The fringe pattern being analysed may contain circular, elliptic or astigmatic fringes. The Fourier transform of such interferograms is seen to be also a sine or a cosine of a second order polynomial in both the real and imaginary parts. In this work we take a discrete Fourier transform of the fringe patterns and then we take separate inverse discrete transforms of the real and imaginary parts of the frequency spectrum. This results in two new interferograms corresponding to the sine and cosine of the quadratic term of the phase modulated by the sine and cosine of the linear term. The linear term of these interferograms may be recovered with similar procedures of fringe analysis from open fringe interferograms. Once the linear term is retrieved the quadratic phase of the interferogram being analysed can also be calculated. The present approach is also being investigated for interferograms with nearly circularly symmetry given that the phase contains some tilt. The described procedure of Fourier analysis from quadratic phase interferograms of nearly symmetric interferograms could be used instead of complex and time consuming algorithms for phase recovery from fringe patterns with closed fringes. Finally, the method is tested in simulated and real data.
Fourier analysis: from cloaking to imaging
NASA Astrophysics Data System (ADS)
Wu, Kedi; Cheng, Qiluan; Wang, Guo Ping
2016-04-01
Regarding invisibility cloaks as an optical imaging system, we present a Fourier approach to analytically unify both Pendry cloaks and complementary media-based invisibility cloaks into one kind of cloak. By synthesizing different transfer functions, we can construct different devices to realize a series of interesting functions such as hiding objects (events), creating illusions, and performing perfect imaging. In this article, we give a brief review on recent works of applying Fourier approach to analysis invisibility cloaks and optical imaging through scattering layers. We show that, to construct devices to conceal an object, no constructive materials with extreme properties are required, making most, if not all, of the above functions realizable by using naturally occurring materials. As instances, we experimentally verify a method of directionally hiding distant objects and create illusions by using all-dielectric materials, and further demonstrate a non-invasive method of imaging objects completely hidden by scattering layers.
Effects of data gaps on Fourier Analysis
NASA Astrophysics Data System (ADS)
Negrea, Catalin; Munteanu, Costel; Echim, Marius
2014-05-01
Fourier Analysis is a vital and widely used tool in all branches of science that require advanced data processing. The method is often used via the Fast Fourier Transform (FFT) implementation readily available in most programming languages. This is a valid approach for data sets with equally spaced data points and no gaps. Such conditions are not always met in real situations where corrections and adjustments to the method are needed. We investigate the intrinsic limitations of four such methods when data gaps are present: 1) linear interpolations and FFT, 2) a direct implementation of the Discrete Fourier Transform, 3) a Z-Transform and 4) the Lomb-Scargle algorithm. Theoretical analysis tools can provide an insight as to the likely problems of such methods and we discuss the likely modifications to the computed spectra. Also, a time series with no data gaps and a constant sampling frequency is altered by introducing several gap configurations and the resulting spectra with the four methods are compared to highlight changes with respect to the original spectrum. Effects on the amplitude and phase of the resulting power spectral densities are analyzed for non-uniformly sampled solar wind data provided by the Venus Express spacecraft. Phase effects are also studied in the context of a sliding window approach. Research supported by the European Community's Seventh Framework Programme (FP7/2007-2013) under grant agreement no 313038/STORM, and a grant of the Romanian Ministry of National Education, CNCS - UEFISCDI, project number PN-II-ID-PCE-2012-4-0418.
Fourier analysis of biological signals with a programmable calculator.
Avolio, A P
1984-01-01
A Fourier analysis program written for the Texas Instruments TI-59 programmable calculator is presented. The program determines the Fourier coefficients of any time varying periodic signal. PMID:6546911
Fourier analysis of multitracer cosmological surveys
NASA Astrophysics Data System (ADS)
Abramo, L. Raul; Secco, Lucas F.; Loureiro, Arthur
2016-02-01
We present optimal quadratic estimators for the Fourier analysis of cosmological surveys that detect several different types of tracers of large-scale structure. Our estimators can be used to simultaneously fit the matter power spectrum and the biases of the tracers - as well as redshift-space distortions (RSDs), non-Gaussianities (NGs), or any other effects that are manifested through differences between the clusterings of distinct species of tracers. Our estimators reduce to the one by Feldman, Kaiser & Peacock (FKP) in the case of a survey consisting of a single species of tracer. We show that the multitracer estimators are unbiased, and that their covariance is given by the inverse of the multitracer Fisher matrix. When the biases, RSDs and NGs are fixed to their fiducial values, and one is only interested in measuring the underlying power spectrum, our estimators are projected into the estimator found by Percival, Verde & Peacock. We have tested our estimators on simple (lognormal) simulated galaxy maps, and we show that it performs as expected, being either equivalent or superior to the FKP method in all cases we analysed. Finally, we have shown how to extend the multitracer technique to include the one-halo term of the power spectrum.
Fourier functional analysis for unsteady aerodynamic modeling
NASA Technical Reports Server (NTRS)
Lan, C. Edward; Chin, Suei
1991-01-01
A method based on Fourier analysis is developed to analyze the force and moment data obtained in large amplitude forced oscillation tests at high angles of attack. The aerodynamic models for normal force, lift, drag, and pitching moment coefficients are built up from a set of aerodynamic responses to harmonic motions at different frequencies. Based on the aerodynamic models of harmonic data, the indicial responses are formed. The final expressions for the models involve time integrals of the indicial type advocated by Tobak and Schiff. Results from linear two- and three-dimensional unsteady aerodynamic theories as well as test data for a 70-degree delta wing are used to verify the models. It is shown that the present modeling method is accurate in producing the aerodynamic responses to harmonic motions and the ramp type motions. The model also produces correct trend for a 70-degree delta wing in harmonic motion with different mean angles-of-attack. However, the current model cannot be used to extrapolate data to higher angles-of-attack than that of the harmonic motions which form the aerodynamic model. For linear ramp motions, a special method is used to calculate the corresponding frequency and phase angle at a given time. The calculated results from modeling show a higher lift peak for linear ramp motion than for harmonic ramp motion. The current model also shows reasonably good results for the lift responses at different angles of attack.
Analysis of eccentric photorefraction by Fourier optics
NASA Astrophysics Data System (ADS)
Liu, Yong; Chen, Jiabi
2007-03-01
Eccentric photorefraction usually is used as early eyesight diagnostic test of infants and small children. Unlike currently approved geometrical optical model of eccentric photorefractometer, the crescent formation and the light-intensity distribution in the pupil image of a myopic eye are analyzed by Fourier optics with the assumption of an isotropic scattering retina. In the case of little circular light source and rectangular slit, the simulation results of different myopic diopters are obtained by geometrical optical theory and Fourier optics respectively. It is found that the simulation results by Fourier optics are similar as those obtained by geometrical optics, and all simulations are almost corresponding to the experimental result. The result demonstrates that the new method presented here is feasible.
Double Fourier analysis for Emotion Identification in Voiced Speech
NASA Astrophysics Data System (ADS)
Sierra-Sosa, D.; Bastidas, M.; Ortiz P., D.; Quintero, O. L.
2016-04-01
We propose a novel analysis alternative, based on two Fourier Transforms for emotion recognition from speech. Fourier analysis allows for display and synthesizes different signals, in terms of power spectral density distributions. A spectrogram of the voice signal is obtained performing a short time Fourier Transform with Gaussian windows, this spectrogram portraits frequency related features, such as vocal tract resonances and quasi-periodic excitations during voiced sounds. Emotions induce such characteristics in speech, which become apparent in spectrogram time-frequency distributions. Later, the signal time-frequency representation from spectrogram is considered an image, and processed through a 2-dimensional Fourier Transform in order to perform the spatial Fourier analysis from it. Finally features related with emotions in voiced speech are extracted and presented.
Electrocardiogram analysis through time discrete Fourier transform
NASA Astrophysics Data System (ADS)
Lancaster, Cameron; Zhang, Guoping
2011-03-01
The motivation for this research is to find an alternative method to diagnose heart conditions. This can be accomplished by analyzing wave patterns in EKG data, and using the Fourier Transform to compare steady wave patterns against fibrillating wave patterns. The two main contributors are the following: heart electricity and Fourier Transform. Also, it is recognized that ion movement has potential to change the frequency in any heart beat signal. This effect is caused due to a strong electrostatic attraction that causes the membrane capacitance to build charge. For a single ion focus, the Nernst Potential influences the equilibrium potential for the membrane of an ion. If two or more ions are contributing to an electric field charge, the Goldman-Hodgkin-Katz will find the membrane equilibrium potential. If a membrane has an efflux, or influx, of ions, then it is possible to get the passive flow of the electric current to zero. In continued research, we will gain knowledge of solving equations; such as ionic flux, quantitative diffusion, electric current density, and more. The finishing portion of this research will be to compare the Fourier Transformed wave graphs to determine heart conditions. Supported by U.S. Department of Energy under Contract No. DE-FG02-06ER46304 and Indiana State University.
Fourier mode analysis of source iteration in spatially periodic media
Zika, M.R.; Larsen, E.W.
1998-12-31
The standard Fourier mode analysis is an indispensable tool when designing acceleration techniques for transport iterations; however, it requires the assumption of a homogeneous infinite medium. For problems of practical interest, material heterogeneities may significantly impact iterative performance. Recent work has applied a Fourier analysis to the discretized two-dimensional transport operator with heterogeneous material properties. The results of these analyses may be difficult to interpret because the heterogeneity effects are inherently coupled to the discretization effects. Here, the authors describe a Fourier analysis of source iteration (SI) that allows the calculation of the eigenvalue spectrum for the one-dimensional continuous transport operator with spatially periodic heterogeneous media.
NASA Astrophysics Data System (ADS)
Laude, David A., Jr.; Johlman, Carolyn; Wilkins, Charles L.
1985-12-01
During the past few years it has been demonstrated that linkage of multiple spectrometry systems with gas chromatography (GC) offers significant advantages for structural analysis of mixture components as they are sepa-rated. In the work to be described, a Fourier transform mass spectrometer (FTMS) has been linked in parallel with a Fourier transform infrared (FTIR) spectrometer for concurrent analysis of GC eluants from a fused silica capillary column. This system provides FTIR, electron impact, and chemical ionization mass spectral analysis of each mixture component as it emerges from the GC. Furthermore, mass measurement accuracy in the low ppm range in the absence of calibrant is made possible by the FTMS. Effective use of the com-plementary information obtained is shown to produce more reliable analytical performance than for any individual measurement.
Xgremlin: Interferograms and spectra from Fourier transform spectrometers analysis
NASA Astrophysics Data System (ADS)
Nave, G.; Griesmann, U.; Brault, J. W.; Abrams, M. C.
2015-11-01
Xgremlin is a hardware and operating system independent version of the data analysis program Gremlin used for Fourier transform spectrometry. Xgremlin runs on PCs and workstations that use the X11 window system, including cygwin in Windows. It is used to Fourier transform interferograms, plot spectra, perform phase corrections, perform intensity and wavenumber calibration, and find and fit spectral lines. It can also be used to construct synthetic spectra, subtract continua, compare several different spectra, and eliminate ringing around lines.
Comparative analysis of imaging configurations and objectives for Fourier microscopy.
Kurvits, Jonathan A; Jiang, Mingming; Zia, Rashid
2015-11-01
Fourier microscopy is becoming an increasingly important tool for the analysis of optical nanostructures and quantum emitters. However, achieving quantitative Fourier space measurements requires a thorough understanding of the impact of aberrations introduced by optical microscopes that have been optimized for conventional real-space imaging. Here we present a detailed framework for analyzing the performance of microscope objectives for several common Fourier imaging configurations. To this end, we model objectives from Nikon, Olympus, and Zeiss using parameters that were inferred from patent literature and confirmed, where possible, by physical disassembly. We then examine the aberrations most relevant to Fourier microscopy, including the alignment tolerances of apodization factors for different objective classes, the effect of magnification on the modulation transfer function, and vignetting-induced reductions of the effective numerical aperture for wide-field measurements. Based on this analysis, we identify an optimal objective class and imaging configuration for Fourier microscopy. In addition, the Zemax files for the objectives and setups used in this analysis have been made publicly available as a resource for future studies. PMID:26560923
Fast Fourier transform analysis of rotor-bearing systems
NASA Technical Reports Server (NTRS)
Choy, K. C.; Gunter, E. J.; Allaire, P. E.
1978-01-01
Nonlinear transient analysis of rotor-bearing systems is becoming increasingly important in the analysis of modern-day rotating machinery to model such phenomena as oil film whirl. This paper develops an analysis technique incorporating modal analysis and fast Fourier transform techniques to analyze rotors with residual shaft bow and realistic nonlinear bearings. The technique is demonstrated on single-mass and three-mass rotor examples. Comparisons of the theoretical results with experimental data give excellent agreement.
Fourier analysis of finite element preconditioned collocation schemes
NASA Technical Reports Server (NTRS)
Deville, Michel O.; Mund, Ernest H.
1990-01-01
The spectrum of the iteration operator of some finite element preconditioned Fourier collocation schemes is investigated. The first part of the paper analyses one-dimensional elliptic and hyperbolic model problems and the advection-diffusion equation. Analytical expressions of the eigenvalues are obtained with use of symbolic computation. The second part of the paper considers the set of one-dimensional differential equations resulting from Fourier analysis (in the tranverse direction) of the 2-D Stokes problem. All results agree with previous conclusions on the numerical efficiency of finite element preconditioning schemes.
Discrete Fourier Transform Analysis in a Complex Vector Space
NASA Technical Reports Server (NTRS)
Dean, Bruce H.
2009-01-01
Alternative computational strategies for the Discrete Fourier Transform (DFT) have been developed using analysis of geometric manifolds. This approach provides a general framework for performing DFT calculations, and suggests a more efficient implementation of the DFT for applications using iterative transform methods, particularly phase retrieval. The DFT can thus be implemented using fewer operations when compared to the usual DFT counterpart. The software decreases the run time of the DFT in certain applications such as phase retrieval that iteratively call the DFT function. The algorithm exploits a special computational approach based on analysis of the DFT as a transformation in a complex vector space. As such, this approach has the potential to realize a DFT computation that approaches N operations versus Nlog(N) operations for the equivalent Fast Fourier Transform (FFT) calculation.
On One Application of Fourier Analysis in Plastic Surgery
NASA Astrophysics Data System (ADS)
Rakhimov, Abdumalik; Zainuddin, Hishamuddin
In present paper, we discuss the spectral methods of measurement of the degree of speech and/or quality of sound by comparing the coefficient of performance indicators depending on energy distributions, ratio of energy of the fundamental tone and energy of overtones. Such a method is very efficient for string oscillation with different initial conditions and it is useful for justification of applications of Fourier analysis in plastic surgery in treatment of some medical diseases.
Two-Dimensional Fourier Transform Analysis of Helicopter Flyover Noise
NASA Technical Reports Server (NTRS)
SantaMaria, Odilyn L.; Farassat, F.; Morris, Philip J.
1999-01-01
A method to separate main rotor and tail rotor noise from a helicopter in flight is explored. Being the sum of two periodic signals of disproportionate, or incommensurate frequencies, helicopter noise is neither periodic nor stationary. The single Fourier transform divides signal energy into frequency bins of equal size. Incommensurate frequencies are therefore not adequately represented by any one chosen data block size. A two-dimensional Fourier analysis method is used to separate main rotor and tail rotor noise. The two-dimensional spectral analysis method is first applied to simulated signals. This initial analysis gives an idea of the characteristics of the two-dimensional autocorrelations and spectra. Data from a helicopter flight test is analyzed in two dimensions. The test aircraft are a Boeing MD902 Explorer (no tail rotor) and a Sikorsky S-76 (4-bladed tail rotor). The results show that the main rotor and tail rotor signals can indeed be separated in the two-dimensional Fourier transform spectrum. The separation occurs along the diagonals associated with the frequencies of interest. These diagonals are individual spectra containing only information related to one particular frequency.
Fourier analysis of conductive heat transfer for glazed roofing materials
Roslan, Nurhana Lyana; Bahaman, Nurfaradila; Almanan, Raja Noorliyana Raja; Ismail, Razidah; Zakaria, Nor Zaini
2014-07-10
For low-rise buildings, roof is the most exposed surface to solar radiation. The main mode of heat transfer from outdoor via the roof is conduction. The rate of heat transfer and the thermal impact is dependent on the thermophysical properties of roofing materials. Thus, it is important to analyze the heat distribution for the various types of roofing materials. The objectives of this paper are to obtain the Fourier series for the conductive heat transfer for two types of glazed roofing materials, namely polycarbonate and polyfilled, and also to determine the relationship between the ambient temperature and the conductive heat transfer for these materials. Ambient and surface temperature data were collected from an empirical field investigation in the campus of Universiti Teknologi MARA Shah Alam. The roofing materials were installed on free-standing structures in natural ventilation. Since the temperature data are generally periodic, Fourier series and numerical harmonic analysis are applied. Based on the 24-point harmonic analysis, the eleventh order harmonics is found to generate an adequate Fourier series expansion for both glazed roofing materials. In addition, there exists a linear relationship between the ambient temperature and the conductive heat transfer for both glazed roofing materials. Based on the gradient of the graphs, lower heat transfer is indicated through polyfilled. Thus polyfilled would have a lower thermal impact compared to polycarbonate.
Vortex metrology using Fourier analysis techniques: vortex networks correlation fringes.
Angel-Toro, Luciano; Sierra-Sosa, Daniel; Tebaldi, Myrian; Bolognini, Néstor
2012-10-20
In this work, we introduce an alternative method of analysis in vortex metrology based on the application of the Fourier optics techniques. The first part of the procedure is conducted as is usual in vortex metrology for uniform in-plane displacement determination. On the basis of two recorded intensity speckled distributions, corresponding to two states of a diffuser coherently illuminated, we numerically generate an analytical signal from each recorded intensity pattern by using a version of the Riesz integral transform. Then, from each analytical signal, a two-dimensional pseudophase map is generated in which the vortices are located and characterized in terms of their topological charges and their core's structural properties. The second part of the procedure allows obtaining Young's interference fringes when Fourier transforming the light passing through a diffracting mask with multiple apertures at the locations of the homologous vortices. In fact, we use the Fourier transform as a mathematical operation to compute the far-field diffraction intensity pattern corresponding to the multiaperture set. Each aperture from the set is associated with a rectangular hole that coincides both in shape and size with a pixel from recorded images. We show that the fringe analysis can be conducted as in speckle photography in an extended range of displacement measurements. Effects related with speckled decorrelation are also considered. Our experimental results agree with those of speckle photography in the range in which both techniques are applicable. PMID:23089799
Fourier analysis of conductive heat transfer for glazed roofing materials
NASA Astrophysics Data System (ADS)
Roslan, Nurhana Lyana; Bahaman, Nurfaradila; Almanan, Raja Noorliyana Raja; Ismail, Razidah; Zakaria, Nor Zaini
2014-07-01
For low-rise buildings, roof is the most exposed surface to solar radiation. The main mode of heat transfer from outdoor via the roof is conduction. The rate of heat transfer and the thermal impact is dependent on the thermophysical properties of roofing materials. Thus, it is important to analyze the heat distribution for the various types of roofing materials. The objectives of this paper are to obtain the Fourier series for the conductive heat transfer for two types of glazed roofing materials, namely polycarbonate and polyfilled, and also to determine the relationship between the ambient temperature and the conductive heat transfer for these materials. Ambient and surface temperature data were collected from an empirical field investigation in the campus of Universiti Teknologi MARA Shah Alam. The roofing materials were installed on free-standing structures in natural ventilation. Since the temperature data are generally periodic, Fourier series and numerical harmonic analysis are applied. Based on the 24-point harmonic analysis, the eleventh order harmonics is found to generate an adequate Fourier series expansion for both glazed roofing materials. In addition, there exists a linear relationship between the ambient temperature and the conductive heat transfer for both glazed roofing materials. Based on the gradient of the graphs, lower heat transfer is indicated through polyfilled. Thus polyfilled would have a lower thermal impact compared to polycarbonate.
Speech processing based on short-time Fourier analysis
Portnoff, M.R.
1981-06-02
Short-time Fourier analysis (STFA) is a mathematical technique that represents nonstationary signals, such as speech, music, and seismic signals in terms of time-varying spectra. This representation provides a formalism for such intuitive notions as time-varying frequency components and pitch contours. Consequently, STFA is useful for speech analysis and speech processing. This paper shows that STFA provides a convenient technique for estimating and modifying certain perceptual parameters of speech. As an example of an application of STFA of speech, the problem of time-compression or expansion of speech, while preserving pitch and time-varying frequency content is presented.
Fourier analysis and signal processing by use of the Moebius inversion formula
NASA Technical Reports Server (NTRS)
Reed, Irving S.; Yu, Xiaoli; Shih, Ming-Tang; Tufts, Donald W.; Truong, T. K.
1990-01-01
A novel Fourier technique for digital signal processing is developed. This approach to Fourier analysis is based on the number-theoretic method of the Moebius inversion of series. The Fourier transform method developed is shown also to yield the convolution of two signals. A computer simulation shows that this method for finding Fourier coefficients is quite suitable for digital signal processing. It competes with the classical FFT (fast Fourier transform) approach in terms of accuracy, complexity, and speed.
Spatial Fourier analysis of video photobleaching measurements. Principles and optimization.
Tsay, T T; Jacobson, K A
1991-08-01
The major use of the fluorescence recovery after photobleaching (FRAP) technique is to measure the translational motion of the molecular components in various condensed media. In a conventional laser spot photobleaching experiment, a photomultiplier is used to measure the total brightness levels of the bleached region in the sample, so no spatial information can be directly obtained. In video-FRAP, a series of images after photobleaching is acquired, allowing the spatial character of the recovery to be determined; this permits direct detection of both anisotropic diffusion and flow. To utilize all of the available image data to determine the transport coefficients, a two-dimensional spatial Fourier transform analysis of the images after photobleaching was employed. The change in the transform between two time points reflects the action of diffusion during the interim. An important advantage of this method, which involves taking the ratio of image transforms at different time points, is that it does not require a specific initial condition to be created by laser photobleaching. The ability of the analysis to extract transport coefficients from computer-simulated diffusional recovery is assessed in the presence of increasing amounts of noise. Experimental data analysis from the diffusion of proteins in viscous solutions and from the diffusion of protein receptors on cell surfaces demonstrate the feasibility of the Fourier analysis to obtain transport coefficients from the video FRAP measurement. PMID:1912279
Particle field holography data reduction by Fourier transform analysis
NASA Technical Reports Server (NTRS)
Hess, Cecil F.; Trolinger, James D.
1987-01-01
The size distribution of a particle field hologram is obtained with a Fourier transformation of the Fraunhofer diffraction pattern of the reconstructed hologram. Off-axis absorption holograms of particle fields with known characteristics were obtained and analyzed with a commercially available instrument. The mean particle size of the reconstructed hologram was measured with an error of + or - 5 percent, while the distribution broadening was estimated within + or - 15 percent. Small sections of a pulsed laser hologram of a synthetic fuel spray were analyzed with this method thus yielding a spatially resolved size distribution. The method yields fast and accurate automated analysis of particle field holograms.
Non-Harmonic Fourier Analysis for bladed wheels damage detection
NASA Astrophysics Data System (ADS)
Neri, P.; Peeters, B.
2015-11-01
The interaction between bladed wheels and the fluid distributed by the stator vanes results in cyclic loading of the rotating components. Compressors and turbines wheels are subject to vibration and fatigue issues, especially when resonance conditions are excited. Even if resonance conditions can be often predicted and avoided, high cycle fatigue failures can occur, causing safety issues and economic loss. Rigorous maintenance programs are then needed, forcing the system to expensive shut-down. Blade crack detection methods are beneficial for condition-based maintenance. While contact measurement systems are not always usable in exercise conditions (e.g. high temperature), non-contact methods can be more suitable. One (or more) stator-fixed sensor can measure all the blades as they pass by, in order to detect the damaged ones. The main drawback in this situation is the short acquisition time available for each blade, which is shortened by the high rotational speed of the components. A traditional Discrete Fourier Transform (DFT) analysis would result in a poor frequency resolution. A Non-Harmonic Fourier Analysis (NHFA) can be executed with an arbitrary frequency resolution instead, allowing to obtain frequency information even with short-time data samples. This paper shows an analytical investigation of the NHFA method. A data processing algorithm is then proposed to obtain frequency shift information from short time samples. The performances of this algorithm are then studied by experimental and numerical tests.
Quantitative assessment of human body shape using Fourier analysis
NASA Astrophysics Data System (ADS)
Friess, Martin; Rohlf, F. J.; Hsiao, Hongwei
2004-04-01
Fall protection harnesses are commonly used to reduce the number and severity of injuries. Increasing the efficiency of harness design requires the size and shape variation of the user population to be assessed as detailed and as accurately as possible. In light of the unsatisfactory performance of traditional anthropometry with respect to such assessments, we propose the use of 3D laser surface scans of whole bodies and the statistical analysis of elliptic Fourier coefficients. Ninety-eight male and female adults were scanned. Key features of each torso were extracted as a 3D curve along front, back and the thighs. A 3D extension of Elliptic Fourier analysis4 was used to quantify their shape through multivariate statistics. Shape change as a function of size (allometry) was predicted by regressing the coefficients onto stature, weight and hip circumference. Upper and lower limits of torso shape variation were determined and can be used to redefine the design of the harness that will fit most individual body shapes. Observed allometric changes are used for adjustments to the harness shape in each size. Finally, the estimated outline data were used as templates for a free-form deformation of the complete torso surface using NURBS models (non-uniform rational B-splines).
The Fourier analysis technique and epsilon-pseudo-eigenvalues
Donato, J.M.
1993-07-01
The spectral radii of iteration matrices and the spectra and condition numbers of preconditioned systems are important in forecasting the convergence rates for iterative methods. Unfortunately, the spectra of iteration matrices or preconditioned systems is rarely easily available. The Fourier analysis technique has been shown to be a useful tool in studying the effectiveness of iterative methods by determining approximate expressions for the eigenvalues or condition numbers of matrix systems. For non-symmetric matrices the eigenvalues may be highly sensitive to perturbations. The spectral radii of nonsymmetric iteration matrices may not give a numerically realistic indication of the convergence of the iterative method. Trefethen and others have presented a theory on the use of {epsilon}-pseudo-eigenvalues in the study of matrix equations. For Toeplitz matrices, we show that the theory of c-pseudo-eigenvalues includes the Fourier analysis technique as a limiting case. For non-Toeplitz matrices, the relationship is not clear. We shall examine this relationship for non-Toeplitz matrices that arise when studying preconditioned systems for methods applied to a two-dimensional discretized elliptic differential equation.
A Fourier analysis of symmetry in protein structure.
Taylor, William R; Heringa, Jaap; Baud, Franck; Flores, Tomas P
2002-02-01
The score matrix from a structure comparison program (SAP) was used to search for repeated structures using a Fourier analysis. When tested with artificial data, a simple Fourier transform of the smoothed matrix provided a clear signal of the repeat periodicity that could be used to extract the repeating units with the SAP program. The strength of the Fourier signal was calibrated against the signal from model proteins. The most useful of these was the novel random-walk approach employed to generate realistic 'fake' structures. On the basis of these it was possible to conclude that only a small proportion of protein structures have an unexpected degree of symmetry. Artificially generated 'ideal' folds provided an upper limit on the strength of signal that could be expected from a 'perfectly' repeating compact structure. Unexpectedly, some of the very regular beta-propellor folds attained the same strength but the majority of symmetric structures lay below this region. When native proteins were ranked by the power of their spectrum a wide variety of fold types were seen to score highly. In the betaalpha class, these included the globular betaalpha proteins and the more repetitive leucine-rich betaalpha folds. In the all-beta class; beta-propellors, beta-prisms and beta-helices were found as well as the more globular gamma-crystalin domains. When this ranked list was filtered to remove proteins that contained detectable internal sequence similarity (using the program REPRO), the list became exclusively composed of just globular betaalpha class proteins and in the top 50 re-ranked proteins, only a single 4-fold propellor structure remained. PMID:11917144
Analysis of far-infrared emission Fourier transform spectra
NASA Technical Reports Server (NTRS)
Park, J. H.; Carli, B.
1986-01-01
An analysis method that uses the nonlinear least-squares fit technique has been developed for emission spectra obtained with a Fourier transform spectrometer. This method is used for the analysis of submillimeter-region atmospheric emission spectra obtained with a balloon-borne FT spectrometer that was carried out as a correlative measurement for the Limb IR Monitor of the Stratosphere (LIMS) satellite experiment. The retrieved mixing ratios of H2O and O3 in the stratosphere from four spectral intervals have standard deviations of about 10 percent, and the average values agree to within 10 percent of corresponding results from the LIMS satellite experiment which used a broadband emission radiometer in the IR region.
Gas emission analysis based on Fourier transformed infrared spectroscopy
NASA Astrophysics Data System (ADS)
Shu, Xiaowen; Zhang, Xiaofu; Lian, Xu; Jin, Hui
2014-12-01
Solar occultation flux (SOF), a new optical technology to detect the gas based on the traditional Fourier transformed infrared spectroscopy (FTIR) developed quickly recently. In this paper, the system and the data analysis is investigated. First a multilayer transmission model of solar radiation is simulated. Then the retrieval process is illustrated. In the proceeding of the data analysis, the Levenberg-Marquardt non-linear square fitting is used to obtain the gas column concentration and the related emission ratio. After the theory certification, the built up system is conducted in a fertilizer plant in Hefei city .The results show SOF is available in the practice and the retrieved gas column concentration can give important information about the pollution emission and dispersion
Higher-order Fourier analysis over finite fields and applications
NASA Astrophysics Data System (ADS)
Hatami, Pooya
Higher-order Fourier analysis is a powerful tool in the study of problems in additive and extremal combinatorics, for instance the study of arithmetic progressions in primes, where the traditional Fourier analysis comes short. In recent years, higher-order Fourier analysis has found multiple applications in computer science in fields such as property testing and coding theory. In this thesis, we develop new tools within this theory with several new applications such as a characterization theorem in algebraic property testing. One of our main contributions is a strong near-equidistribution result for regular collections of polynomials. The densities of small linear structures in subsets of Abelian groups can be expressed as certain analytic averages involving linear forms. Higher-order Fourier analysis examines such averages by approximating the indicator function of a subset by a function of bounded number of polynomials. Then, to approximate the average, it suffices to know the joint distribution of the polynomials applied to the linear forms. We prove a near-equidistribution theorem that describes these distributions for the group F(n/p) when p is a fixed prime. This fundamental fact was previously known only under various extra assumptions about the linear forms or the field size. We use this near-equidistribution theorem to settle a conjecture of Gowers and Wolf on the true complexity of systems of linear forms. Our next application is towards a characterization of testable algebraic properties. We prove that every locally characterized affine-invariant property of functions f : F(n/p) → R with n∈ N, is testable. In fact, we prove that any such property P is proximity-obliviously testable. More generally, we show that any affine-invariant property that is closed under subspace restrictions and has "bounded complexity" is testable. We also prove that any property that can be described as the property of decomposing into a known structure of low
Partial differential equation transform — Variational formulation and Fourier analysis
Wang, Yang; Wei, Guo-Wei; Yang, Siyang
2011-01-01
Nonlinear partial differential equation (PDE) models are established approaches for image/signal processing, data analysis and surface construction. Most previous geometric PDEs are utilized as low-pass filters which give rise to image trend information. In an earlier work, we introduced mode decomposition evolution equations (MoDEEs), which behave like high-pass filters and are able to systematically provide intrinsic mode functions (IMFs) of signals and images. Due to their tunable time-frequency localization and perfect reconstruction, the operation of MoDEEs is called a PDE transform. By appropriate selection of PDE transform parameters, we can tune IMFs into trends, edges, textures, noise etc., which can be further utilized in the secondary processing for various purposes. This work introduces the variational formulation, performs the Fourier analysis, and conducts biomedical and biological applications of the proposed PDE transform. The variational formulation offers an algorithm to incorporate two image functions and two sets of low-pass PDE operators in the total energy functional. Two low-pass PDE operators have different signs, leading to energy disparity, while a coupling term, acting as a relative fidelity of two image functions, is introduced to reduce the disparity of two energy components. We construct variational PDE transforms by using Euler-Lagrange equation and artificial time propagation. Fourier analysis of a simplified PDE transform is presented to shed light on the filter properties of high order PDE transforms. Such an analysis also offers insight on the parameter selection of the PDE transform. The proposed PDE transform algorithm is validated by numerous benchmark tests. In one selected challenging example, we illustrate the ability of PDE transform to separate two adjacent frequencies of sin(x) and sin(1.1x). Such an ability is due to PDE transform’s controllable frequency localization obtained by adjusting the order of PDEs. The
Gas Analysis by Fourier Transform Mm-Wave Spectroscopy
NASA Astrophysics Data System (ADS)
Harris, Brent J.; Steber, Amanda L.; Lehmann, Kevin K.; Pate, Brooks H.
2013-06-01
Molecular rotational spectroscopy of low pressure, room temperature gases offers high chemical selectivity and sensitivity with the potential for a wide range of applications in gas analysis. A strength of the technique is the potential to identify molecules that have not been previously studied by rotational spectroscopy by comparing experimental results to predictions of the spectroscopic parameters from quantum chemistry -6 so called library-free detection. The development of Fourier transform mm-wave spectrometers using high peak power (30 mW) active multiplier chain mm-wave sources brings new measurement capabilities to the analysis of complex gas mixtures. Strategies for gas analysis based on high-throughput mm-wave spectroscopy and arbitrary waveform generator driven mm-wave sources are described. Several new measurement capabilities come from the intrinsic time-domain measurement technique. High-sensitivity double-resonance measurements can be performed to speed the analysis of a complex gas sample containing several species. This technique uses a "pi-pulse" to selectively invert the population of two selected rotational energy levels and the effect of this excitation pulse on all other transitions in the spectrometer operating range is monitored using segmented chirped-pulse Fourier transform spectroscopy. This method can lead to automated determination of the molecular rotational constants. Rapid pulse duration scan experiments can be used to estimate the magnitude and direction of the dipole moment of the molecule from an unknown spectrum. Coherent pulse echo experiments, using the traditional Hahn sequence or two-color population recovery methods, can be used to determine the collisional relaxation rate of the unknown molecule. This rate determination improves the ability to estimate the mass of the unknown molecule from the determination of the Doppler dephasing rate. By performing a suite of automated, high-throughput measurements, there is the
Error analysis for the Fourier domain offset estimation algorithm
NASA Astrophysics Data System (ADS)
Wei, Ling; He, Jieling; He, Yi; Yang, Jinsheng; Li, Xiqi; Shi, Guohua; Zhang, Yudong
2016-02-01
The offset estimation algorithm is crucial for the accuracy of the Shack-Hartmann wave-front sensor. Recently, the Fourier Domain Offset (FDO) algorithm has been proposed for offset estimation. Similar to other algorithms, the accuracy of FDO is affected by noise such as background noise, photon noise, and 'fake' spots. However, no adequate quantitative error analysis has been performed for FDO in previous studies, which is of great importance for practical applications of the FDO. In this study, we quantitatively analysed how the estimation error of FDO is affected by noise based on theoretical deduction, numerical simulation, and experiments. The results demonstrate that the standard deviation of the wobbling error is: (1) inversely proportional to the raw signal to noise ratio, and proportional to the square of the sub-aperture size in the presence of background noise; and (2) proportional to the square root of the intensity in the presence of photonic noise. Furthermore, the upper bound of the estimation error is proportional to the intensity of 'fake' spots and the sub-aperture size. The results of the simulation and experiments agreed with the theoretical analysis.
HIGH RESOLUTION FOURIER ANALYSIS WITH AUTO-REGRESSIVE LINEAR PREDICTION
Barton, J.; Shirley, D.A.
1984-04-01
Auto-regressive linear prediction is adapted to double the resolution of Angle-Resolved Photoemission Extended Fine Structure (ARPEFS) Fourier transforms. Even with the optimal taper (weighting function), the commonly used taper-and-transform Fourier method has limited resolution: it assumes the signal is zero beyond the limits of the measurement. By seeking the Fourier spectrum of an infinite extent oscillation consistent with the measurements but otherwise having maximum entropy, the errors caused by finite data range can be reduced. Our procedure developed to implement this concept adapts auto-regressive linear prediction to extrapolate the signal in an effective and controllable manner. Difficulties encountered when processing actual ARPEFS data are discussed. A key feature of this approach is the ability to convert improved measurements (signal-to-noise or point density) into improved Fourier resolution.
FOURIER ANALYSIS OF EXTENDED FINE STRUCTURE WITH AUTOREGRESSIVE PREDICTION
Barton, J.; Shirley, D.A.
1985-01-01
Autoregressive prediction is adapted to double the resolution of Angle-Resolved Photoemission Extended Fine Structure (ARPEFS) Fourier transforms. Even with the optimal taper (weighting function), the commonly used taper-and-transform Fourier method has limited resolution: it assumes the signal is zero beyond the limits of the measurement. By seeking the Fourier spectrum of an infinite extent oscillation consistent with the measurements but otherwise having maximum entropy, the errors caused by finite data range can be reduced. Our procedure developed to implement this concept applies autoregressive prediction to extrapolate the signal to an extent controlled by a taper width. Difficulties encountered when processing actual ARPEFS data are discussed. A key feature of this approach is the ability to convert improved measurements (signal-to-noise or point density) into improved Fourier resolution.
Cutoff probe using Fourier analysis for electron density measurement
NASA Astrophysics Data System (ADS)
Na, Byung-Keun; You, Kwang-Ho; Kim, Dae-Woong; Chang, Hong-Young; You, Shin-Jae; Kim, Jung-Hyung
2012-01-01
This paper proposes a new method for cutoff probe using a nanosecond impulse generator and an oscilloscope, instead of a network analyzer. The nanosecond impulse generator supplies a radiating signal of broadband frequency spectrum simultaneously without frequency sweeping, while frequency sweeping method is used by a network analyzer in a previous method. The transmission spectrum (S21) was obtained through a Fourier analysis of the transmitted impulse signal detected by the oscilloscope and was used to measure the electron density. The results showed that the transmission frequency spectrum and the electron density obtained with a new method are very close to those obtained with a previous method using a network analyzer. And also, only 15 ns long signal was necessary for spectrum reconstruction. These results were also compared to the Langmuir probe's measurements with satisfactory results. This method is expected to provide not only fast measurement of absolute electron density, but also function in other diagnostic situations where a network analyzer would be used (a hairpin probe and an impedance probe) by replacing the network analyzer with a nanosecond impulse generator and an oscilloscope.
Fourier analysis of polar cap electric field and current distributions
NASA Technical Reports Server (NTRS)
Barbosa, D. D.
1984-01-01
A theoretical study of high-latitude electric fields and currents, using analytic Fourier analysis methods, is conducted. A two-dimensional planar model of the ionosphere with an enhanced conductivity auroral belt and field-aligned currents at the edges is employed. Two separate topics are treated. A field-aligned current element near the cusp region of the polar cap is included to investigate the modifications to the convection pattern by the east-west component of the interplanetary magnetic field. It is shown that a sizable one-cell structure is induced near the cusp which diverts equipotential contours to the dawnside or duskside, depending on the sign of the cusp current. This produces characteristic dawn-dusk asymmetries to the electric field that have been previously observed over the polar cap. The second topic is concerned with the electric field configuration obtained in the limit of perfect shielding, where the field is totally excluded equatorward of the auroral oval. When realistic field-aligned current distributions are used, the result is to produce severely distorted, crescent-shaped equipotential contours over the cap. Exact, analytic formulae applicable to this case are also provided.
On the Fourier and Wavelet Analysis of Coronal Time Series
NASA Astrophysics Data System (ADS)
Auchère, F.; Froment, C.; Bocchialini, K.; Buchlin, E.; Solomon, J.
2016-07-01
Using Fourier and wavelet analysis, we critically re-assess the significance of our detection of periodic pulsations in coronal loops. We show that the proper identification of the frequency dependence and statistical properties of the different components of the power spectra provides a strong argument against the common practice of data detrending, which tends to produce spurious detections around the cut-off frequency of the filter. In addition, the white and red noise models built into the widely used wavelet code of Torrence & Compo cannot, in most cases, adequately represent the power spectra of coronal time series, thus also possibly causing false positives. Both effects suggest that several reports of periodic phenomena should be re-examined. The Torrence & Compo code nonetheless effectively computes rigorous confidence levels if provided with pertinent models of mean power spectra, and we describe the appropriate manner in which to call its core routines. We recall the meaning of the default confidence levels output from the code, and we propose new Monte-Carlo-derived levels that take into account the total number of degrees of freedom in the wavelet spectra. These improvements allow us to confirm that the power peaks that we detected have a very low probability of being caused by noise.
Fixed-point error analysis of Winograd Fourier transform algorithms
NASA Technical Reports Server (NTRS)
Patterson, R. W.; Mcclellan, J. H.
1978-01-01
The quantization error introduced by the Winograd Fourier transform algorithm (WFTA) when implemented in fixed-point arithmetic is studied and compared with that of the fast Fourier transform (FFT). The effect of ordering the computational modules and the relative contributions of data quantization error and coefficient quantization error are determined. In addition, the quantization error introduced by the Good-Winograd (GW) algorithm, which uses Good's prime-factor decomposition for the discrete Fourier transform (DFT) together with Winograd's short length DFT algorithms, is studied. Error introduced by the WFTA is, in all cases, worse than that of the FFT. In general, the WFTA requires one or two more bits for data representation to give an error similar to that of the FFT. Error introduced by the GW algorithm is approximately the same as that of the FFT.
Using musical intervals to demonstrate superposition of waves and Fourier analysis
NASA Astrophysics Data System (ADS)
LoPresto, Michael C.
2013-09-01
What follows is a description of a demonstration of superposition of waves and Fourier analysis using a set of four tuning forks mounted on resonance boxes and oscilloscope software to create, capture and analyze the waveforms and Fourier spectra of musical intervals.
Using Musical Intervals to Demonstrate Superposition of Waves and Fourier Analysis
ERIC Educational Resources Information Center
LoPresto, Michael C.
2013-01-01
What follows is a description of a demonstration of superposition of waves and Fourier analysis using a set of four tuning forks mounted on resonance boxes and oscilloscope software to create, capture and analyze the waveforms and Fourier spectra of musical intervals.
Transfer function analysis in epi-illumination Fourier ptychography
Pacheco, Shaun; Salahieh, Basel; Milster, Tom; Rodriguez, Jeffrey J.; Liang, Rongguang
2016-01-01
This letter explores Fourier ptychography (FP) using epi-illumination. The approach effectively modifies the FP transfer function to be coherent-like out to the incoherent limit of twice the numerical aperture over the wavelength 2NA/λ. Images reconstructed using this approach are shown to have higher contrast at finer details compared with images using incoherent illumination, indicating that the FP transfer function is superior in high spatial frequency regions. PMID:26565870
Analysis of a thioether lubricant by infrared Fourier microemission spectrophotometry
NASA Technical Reports Server (NTRS)
Jones, W. R., Jr.; Morales, W.; Lauer, J. L.
1986-01-01
An infrared Fourier microemission spectrophotometer is used to obtain spectra (wavenumber range, 630 to 1230 0.1 cm) from microgram quantities of thioether lubricant samples deposited on aluminum foil. Infrared bands in the spectra are reproducible and could be identified as originating from aromatic species (1,3-disubstituted benzenes). Spectra from all samples (neat and formulated, used and unused) are very similar. Additives (an acid and a phosphinate) present in low concentration (0.10 percent) in the formulated fluid are not detected. This instrument appears to be a viable tool in helping to identify lubricant components separated by liquid chromatography.
Fourier analysis of a gated blood-pool study during atrial flutter
Makler, P.T. Jr.; McCarthy, D.M.; London, J.W.; Sandler, M.S.; Alavi, A.
1983-08-01
First-harmonic Fourier analysis of a gated blood-pool study is based on the assumption that the cardiac chambers contract once per cardiac cycle. In atrial arrhythmias this condition may not exist for the atria. We recently studied a patient with atrial flutter and 2:1 artioventricular conduction. There were predictable alterations in the first-harmonic Fourier phase and amplitude images. The observed changes from first-harmonic Fourier analysis were: (a) very low atrial amplitude values, and (b) absence of identifiable atrial regions on the phase image.
Imaging Fourier transform spectrometer (IFTS): parametric sensitivity analysis
NASA Astrophysics Data System (ADS)
Keller, Robert A.; Lomheim, Terrence S.
2005-06-01
Imaging Fourier transform spectrometers (IFTS) allow for very high spectral resolution hyperspectral imaging while using moderate size 2D focal plane arrays in a staring mode. This is not the case for slit scanning dispersive imaging spectrometers where spectral sampling is related to the focal plane pixel count along the spectral dimension of the 2D focal plane used in such an instrument. This can become a major issue in the longwave infrared (LWIR) where the operability and yield of highly sensitivity arrays (i.e.HgCdTe) of large dimension are generally poor. However using an IFTS introduces its own unique set of issues and tradeoffs. In this paper we develop simplified equations for describing the sensitivity of an IFTS, including the effects of data windowing. These equations provide useful insights into the optical, focal plane and operational design trade space that must be considered when examining IFTS concepts aimed at a specific sensitivity and spectral resolution application. The approach is illustrated by computing the LWIR noise-equivalent spectral radiance (NESR) corresponding to the NASA Geosynchronous Imaging Fourier Transform Spectrometer (GIFTS) concept assuming a proven and reasonable noise-equivalent irradiance (NEI) capability for the focal plane.
A Fourier analysis for a fast simulation algorithm. [for switching converters
NASA Technical Reports Server (NTRS)
King, Roger J.
1988-01-01
This paper presents a derivation of compact expressions for the Fourier series analysis of the steady-state solution of a typical switching converter. The modeling procedure for the simulation and the steady-state solution is described, and some desirable traits for its matrix exponential subroutine are discussed. The Fourier analysis algorithm was tested on a phase-controlled parallel-loaded resonant converter, providing an experimental confirmation.
Guided-mode analysis by the Lanczos-Fourier expansion
NASA Astrophysics Data System (ADS)
Koukoutsaki, Panagiota A.; Tigelis, Ioannis G.; Manenkov, Alexander B.
2002-11-01
The Lanczos-Fourier series expansion is employed to analyze the guided-mode field in an asymmetrical slab waveguide, the core of which has an anisotropic and inhomogeneous dielectric permittivity. A system of linear homogeneous equations is derived by the collocation technique with consideration of the wave equation and the appropriate boundary conditions at the interfaces between the core and cladding media. The propagation constants are found from a determinant equation that ensures the existence of a nontrivial solution of the system. Numerical results are presented for several cases of dielectric permittivity, including the constant, parabolic, linear, and anisotropic cases. This approach is found to converge reasonably fast, and Richardson's extrapolation technique is applied to accelerate the convergence further. The approach can be easily generalized from the scalar to the vector equation, and, as an example, we consider the guided modes of a circular fiber.
Gasoline analysis and brand identification using a static Fourier-transform ultraviolet spectrometer
NASA Astrophysics Data System (ADS)
Steers, Darren; Gerrard, Carl; Hirst, Bill; Sibbett, Wilson; Padgett, Miles J.
1999-11-01
The ultraviolet (UV) absorption spectra of several gasoline samples are measured using a compact static Fourier-transform (FT) spectrometer. The FT-UV spectrometer is constructed from crystalline quartz Wollaston prisms and polarizers fabricated from beta barium borate to form an interferogram in the spatial domain. The interferogram is recorded with a UV-sensitive detector array and Fourier transformed to yield spectra. Investigation using principal component analysis enables the identification of important gasoline properties such as origin.
Fourier optics analysis of grating sensors with tilt errors.
Ferhanoglu, Onur; Toy, M Fatih; Urey, Hakan
2011-06-15
Dynamic diffraction gratings can be microfabricated with precision and offer extremely sensitive displacement measurements and light intensity modulation. The effect of pure translation of the moving part of the grating on diffracted order intensities is well known. This study focuses on the parameters that limit the intensity and the contrast of the interference. The effects of grating duty cycle, mirror reflectivities, sensor tilt and detector size are investigated using Fourier optics theory and Gaussian beam optics. Analytical findings reveal that fringe visibility becomes <0.3 when the optical path variation exceeds half the wavelength within the grating interferometer. The fringe visibility can be compensated by monitoring the interfering portion of the diffracted order light only through detector size reduction in the expense of optical power. Experiments were conducted with a grating interferometer that resulted in an eightfold increase in fringe visibility with reduced detector size, which is in agreement with theory. Findings show that diffraction grating readout principle is not limited to translating sensors but also can be used for sensors with tilt or other deflection modes. PMID:21685984
Fourier transform infrared spectroscopic analysis of cell differentiation
NASA Astrophysics Data System (ADS)
Ishii, Katsunori; Kimura, Akinori; Kushibiki, Toshihiro; Awazu, Kunio
2007-02-01
Stem cells and its differentiations have got a lot of attentions in regenerative medicine. The process of differentiations, the formation of tissues, has become better understood by the study using a lot of cell types progressively. These studies of cells and tissue dynamics at molecular levels are carried out through various approaches like histochemical methods, application of molecular biology and immunology. However, in case of using regenerative sources (cells, tissues and biomaterials etc.) clinically, they are measured and quality-controlled by non-invasive methods from the view point of safety. Recently, the use of Fourier Transform Infrared spectroscopy (FT-IR) has been used to monitor biochemical changes in cells, and has gained considerable importance. The objective of this study is to establish the infrared spectroscopy of cell differentiation as a quality control of cell sources for regenerative medicine. In the present study, as a basic study, we examined the adipose differentiation kinetics of preadipocyte (3T3-L1) and the osteoblast differentiation kinetics of bone marrow mesenchymal stem cells (Kusa-A1) to analyze the infrared absorption spectra. As a result, we achieved to analyze the adipose differentiation kinetics using the infrared absorption peak at 1739 cm-1 derived from ester bonds of triglyceride and osteoblast differentiation kinetics using the infrared absorption peak at 1030 cm-1 derived from phosphate groups of calcium phosphate.
Fourier Transform Methods Applied To The Analysis Of Microphotometric Images Of Histologic Sections
NASA Astrophysics Data System (ADS)
Dytch, Harvey E.; Wied, George L.
1989-06-01
Implementation of one-dimensional Fourier transform techniques for the analysis of histologic sections is discussed, as is the motivation for their use. Features of the frequency domain representation derived by such a transform are shown to be related to several important diagnostic clues. The interpretation of the Fourier magnitude spectrum in histologically relevant terms is examined by means of Fourier transforms of idealized tissue simulations. Some of the perturbations of these ideal spectra produced by biologic reality are discussed. Three classic types of cervical epithelial tissue are modeled, and their representation as Fourier magnitude spectra interpreted in the light of the previous results: characteristic frequency domain signatures are obtained for each. It is concluded that these techniques may provide diagnostically important objective measures, and may be applied to otherwise intractable histologic specimens with crowded and overlapping nuclei.
Teaching time-series analysis. I. Finite Fourier analysis of ocean waves
NASA Astrophysics Data System (ADS)
Whitford, Dennis J.; Vieira, Mario E. C.; Waters, Jennifer K.
2001-04-01
The introduction of students to methods of time-series analysis is a pedagogical challenge, since the availability of easily manipulated computer software presents an attractive alternative to an understanding of the computations, as well as their assumptions and limitations. A two-part pedagogical tutorial exercise is offered as a hands-on laboratory to complement classroom discussions or as a reference for students involved in independent research projects. The exercises are focused on the analysis of ocean waves, specifically wind-generated surface gravity waves. The exercises are cross-disciplinary in nature and can be extended to any other field dealing with random signal analysis. The first exercise introduces the manual arithmetic steps of a finite Fourier analysis of a wave record, develops a spectrum, and compares these results to the results obtained using a fast Fourier transform (FFT). The second part of the exercise, described in the subsequent article, takes a longer wave record and addresses the theoretical and observed wave probability distributions of wave heights and sea surface elevations. These results are then compared to a FFT, thus linking the two pedagogical laboratory exercise parts for a more complete understanding of both exercises.
Refined Fourier-transform method of analysis of full two-dimensional digitized interferograms
NASA Astrophysics Data System (ADS)
Lovrić, Davorin; Vučić, Zlatko; Gladić, Jadranko; Demoli, Nazif; Mitrović, Slobodan; Milas, Mirko
2003-03-01
A refined Fourier-transform method of analysis of interference patterns is presented. The refinements include a method of automatic background subtraction and a way of treating the problem of heterodyning. The method proves particularly useful for analysis of long sequences of interferograms.
Assessment of the site of ventricular activation by Fourier analysis of gated blood-pool studies
Links, J.M.; Raichlen, J.S.; Wagner, H.N. Jr.; Reid, P.R.
1985-01-01
The authors studied the use of first-harmonic Fourier analysis of gated blood-pool images to assess the site of ventricular activation in a group of 12 patients undergoing electrophysiologic pacing studies. They acquired gated blood-pool studies during pacing at up to four sites at each of two different rates. A total of 50 studies were made. At a pacing rate of 100 beats/min, when the pacing electrode was the right-ventricular outflow tract, 7/8; at the anterolateral left-ventricular wall, 4/4. When the Fourier activation site was at the right-ventricular apex, 9/9 times the pacing electrode was there; at the right-ventricular outflow tract, 7/10; in the left ventricle, 4/4. Fourier analysis of gated blood-pool studies can help identify the site of ventricular activation but is not sufficiently accurate to fully replace endocardial mapping.
The combined use of order tracking techniques for enhanced Fourier analysis of order components
NASA Astrophysics Data System (ADS)
Wang, K. S.; Heyns, P. S.
2011-04-01
Order tracking is one of the most important vibration analysis techniques for diagnosing faults in rotating machinery. It can be performed in many different ways, each of these with distinct advantages and disadvantages. However, in the end the analyst will often use Fourier analysis to transform the data from a time series to frequency or order spectra. It is therefore surprising that the study of the Fourier analysis of order-tracked systems seems to have been largely ignored in the literature. This paper considers the frequently used Vold-Kalman filter-based order tracking and computed order tracking techniques. The main pros and cons of each technique for Fourier analysis are discussed and the sequential use of Vold-Kalman filtering and computed order tracking is proposed as a novel idea to enhance the results of Fourier analysis for determining the order components. The advantages of the combined use of these order tracking techniques are demonstrated numerically on an SDOF rotor simulation model. Finally, the approach is also demonstrated on experimental data from a real rotating machine.
Wahbi, A M; Abdine, H; Korany, M A
1978-05-01
The basic principle for the use of Fourier functions in spectrophotometric analysis is discussed. Fourier function coefficients are linearly related to concentration and are associated with relative standard deviations of less than 1%. The proper choice of function and range, number of points and the transformation of an absorption curve are discussed. New trigonometric functions are derived to correct for linear irrelevant absorption. The method is illustrated by the determination of progesterone and testosterone propionate in oily solutions without prior chromatography. The results obtained are compared with those obtained using orthogonal polynomials. PMID:674337
Numerical dispersion analysis for three-dimensional Laplace-Fourier-domain scalar wave equation
NASA Astrophysics Data System (ADS)
Chen, Jing-Bo
2016-06-01
Based on the phase velocity and attenuation propagation velocity, a method for performing numerical dispersion analysis of three-dimensional Laplace-Fourier-domain scalar wave equation is presented. This method is applied to a 27-point average-derivative optimal scheme and a 27-point finite-element scheme. Within the relative error of 1%, the 27-point average-derivative optimal scheme requires seven grid points per wavelength and pseudo-wavelength while the 27-point finite-element scheme requires 23 grid points per wavelength and pseudo-wavelength for equal and unequal directional sampling intervals. Numerical examples show that the 27-point Laplace-Fourier-domain average-derivative optimal scheme is more accurate than the 27-point Laplace-Fourier-domain finite-element scheme for the same computational cost. By using larger directional sampling intervals while maintaining accuracy, the 27-point Laplace-Fourier-domain average-derivative optimal scheme can greatly reduce the computational cost of three-dimensional Laplace-Fourier-domain modelling.
Program for the analysis of time series. [by means of fast Fourier transform algorithm
NASA Technical Reports Server (NTRS)
Brown, T. J.; Brown, C. G.; Hardin, J. C.
1974-01-01
A digital computer program for the Fourier analysis of discrete time data is described. The program was designed to handle multiple channels of digitized data on general purpose computer systems. It is written, primarily, in a version of FORTRAN 2 currently in use on CDC 6000 series computers. Some small portions are written in CDC COMPASS, an assembler level code. However, functional descriptions of these portions are provided so that the program may be adapted for use on any facility possessing a FORTRAN compiler and random-access capability. Properly formatted digital data are windowed and analyzed by means of a fast Fourier transform algorithm to generate the following functions: (1) auto and/or cross power spectra, (2) autocorrelations and/or cross correlations, (3) Fourier coefficients, (4) coherence functions, (5) transfer functions, and (6) histograms.
NASA Technical Reports Server (NTRS)
Munoz, R. M. (Inventor)
1974-01-01
An input analog signal to be frequency analyzed is separated into N number of simultaneous analog signal components each identical to the original but delayed relative to the original by a successively larger time delay. The separated and delayed analog components are combined together in a suitable number of adders and attenuators in accordance with at least one component product of the continuous Fourier transform and analog signal matrices to separate the analog input signal into at least one of its continuous analog frequency components of bandwidth 1/N times the bandwidth of the original input signal. The original analog input signal can be reconstituted by combining the separate analog frequency components in accordance with the component products of the continuous Fourier transform and analog frequency component matrices. The continuous Fourier transformation is useful for spectrum analysis, filtering, transfer function synthesis, and communications.
Performance analysis of SHE-PWM using Fourier Series and Newton-Raphson analysis
NASA Astrophysics Data System (ADS)
Lada, M. Y.; Khiar, M. S. A.; Ghani, S. A.; Nawawi, M. R. M.; Nor, A. S. M.; Yuen, J. G. M.
2015-05-01
The performance of inverter has become a vital role in contributing effective power system nowadays. However the major issue that will reduce the inverter performance is the harmonic distortions that contribute to power losses. Thus, there are a variety of controls techniques have been implemented for inverters switching such as square wave, SHE-PWM, unipolar and bipolar. The square wave type inverter produces output voltage in square shape which has simple logic control and power switches. Next, unipolar and bipolar techniques are using comparator to compare the reference voltage waveform with the triangular waveform. The difference between unipolar and bipolar is there are two reference signals which are compared with the triangular waveform for unipolar switching. On the other hand, bipolar switching compares triangular waveform with a reference signal. Selective Harmonic Elimination Pulse-Width Modulation (SHE-PWM) is another control technique for inverters. This research propose SHE-PWM as a low switching frequency strategy that uses Fourier Series and Newton-Raphson analysis to calculate the switching angles for elimination of harmonic distortion. Fourier Series is used to determine the amplitude of any odd harmonic in the output signal whereas Newton-Raphson is used to solve the equation for finding switching angles. As a result, SHE-PWM can select the low frequency harmonic components need to be eliminated and reduce the harmonic distortion. It also prevents the harmonic distortion that sensitive to the inverter performance
Time sequence analysis of flickering auroras. I - Application of Fourier analysis. [in atmosphere
NASA Technical Reports Server (NTRS)
Berkey, F. T.; Silevitch, M. B.; Parsons, N. R.
1980-01-01
Using a technique that enables one to digitize the brightness of auroral displays from individual fields of a video signal, we have analyzed the frequency content of flickering aurora. Through the application of Fourier analysis to our data, we have found that flickering aurora contains a wide range of enhanced frequencies, although the dominant frequency enhancement generally occurs in the range 6-12 Hz. Each incidence of flickering that we observed was associated with increased radio wave absorption. Furthermore, we have found that flickering occurs in bright auroral surges, the occurrence of which is not limited to the 'breakup' phase of auroral substorms. Our results are interpreted in terms of a recently proposed theory of fluctuating double layers that accounts for a number of the observational features.
Novel Algorithm for Polar and Spherical Fourier Analysis on Two and Three Dimensional Images
NASA Astrophysics Data System (ADS)
Yang, Zhuo; Kamata, Sei-Ichiro
Polar and Spherical Fourier analysis can be used to extract rotation invariant features for image retrieval and pattern recognition tasks. They are demonstrated to show superiorities comparing with other methods on describing rotation invariant features of two and three dimensional images. Based on mathematical properties of trigonometric functions and associated Legendre polynomials, fast algorithms are proposed for multimedia applications like real time systems and large multimedia databases in order to increase the computation speed. The symmetric points are computed simultaneously. Inspired by relative prime number theory, systematic analysis are given in this paper. Novel algorithm is deduced that provide even faster speed. Proposed method are 9-15% faster than previous work. The experimental results on two and three dimensional images are given to illustrate the effectiveness of the proposed method. Multimedia signal processing applications that need real time polar and spherical Fourier analysis can be benefit from this work.
Zarabadi, Atefeh S; Pawliszyn, Janusz
2015-02-17
Analysis in the frequency domain is considered a powerful tool to elicit precise information from spectroscopic signals. In this study, the Fourier transformation technique is employed to determine the diffusion coefficient (D) of a number of proteins in the frequency domain. Analytical approaches are investigated for determination of D from both experimental and data treatment viewpoints. The diffusion process is modeled to calculate diffusion coefficients based on the Fourier transformation solution to Fick's law equation, and its results are compared to time domain results. The simulations characterize optimum spatial and temporal conditions and demonstrate the noise tolerance of the method. The proposed model is validated by its application for the electropherograms from the diffusion path of a set of proteins. Real-time dynamic scanning is conducted to monitor dispersion by employing whole column imaging detection technology in combination with capillary isoelectric focusing (CIEF) and the imaging plug flow (iPF) experiment. These experimental techniques provide different peak shapes, which are utilized to demonstrate the Fourier transformation ability in extracting diffusion coefficients out of irregular shape signals. Experimental results confirmed that the Fourier transformation procedure substantially enhanced the accuracy of the determined values compared to those obtained in the time domain. PMID:25607375
Fourier-, Hilbert- and wavelet-based signal analysis: are they really different approaches?
Bruns, Andreas
2004-08-30
Spectral signal analysis constitutes one of the most important and most commonly used analytical tools for the evaluation of neurophysiological signals. It is not only the spectral parameters per se (amplitude and phase) which are of interest, but there is also a variety of measures derived from them, including important coupling measures like coherence or phase synchrony. After reviewing some of these measures in order to underline the widespread relevance of spectral analysis, this report compares the three classical spectral analysis approaches: Fourier, Hilbert and wavelet transform. Recently, there seems to be increasing acceptance of the notion that Hilbert- or wavelet-based analyses be in some way superior to Fourier-based analyses. The present article counters such views by demonstrating that the three techniques are in fact formally (i.e. mathematically) equivalent when using the class of wavelets that is typically applied in spectral analyses. Moreover, spectral amplitude serves as an example to show that Fourier, Hilbert and wavelet analysis also yield equivalent results in practical applications to neuronal signals. PMID:15262077
Establishing a direct connection between detrended fluctuation analysis and Fourier analysis
NASA Astrophysics Data System (ADS)
Kiyono, Ken
2015-10-01
To understand methodological features of the detrended fluctuation analysis (DFA) using a higher-order polynomial fitting, we establish the direct connection between DFA and Fourier analysis. Based on an exact calculation of the single-frequency response of the DFA, the following facts are shown analytically: (1) in the analysis of stochastic processes exhibiting a power-law scaling of the power spectral density (PSD), S (f ) ˜f-β , a higher-order detrending in the DFA has no adverse effect in the estimation of the DFA scaling exponent α , which satisfies the scaling relation α =(β +1 )/2 ; (2) the upper limit of the scaling exponents detectable by the DFA depends on the order of polynomial fit used in the DFA, and is bounded by m +1 , where m is the order of the polynomial fit; (3) the relation between the time scale in the DFA and the corresponding frequency in the PSD are distorted depending on both the order of the DFA and the frequency dependence of the PSD. We can improve the scale distortion by introducing the corrected time scale in the DFA corresponding to the inverse of the frequency scale in the PSD. In addition, our analytical approach makes it possible to characterize variants of the DFA using different types of detrending. As an application, properties of the detrending moving average algorithm are discussed.
Fourier analysis of cell-wise Block-Jacobi splitting in two-dimensional geometry
Rosa, Massimiliano; Warsa, James S; Kelley, Timothy M
2009-01-01
A Fourier analysis is conducted in two-dimensional (2D) geometry for the discrete-ordinates (SN) approximation of the neutron transport problem solved with Richardson iteration (Source Iteration) using the cell-wise Block-Jacobi (B1) algorithm. The results of the Fourier analysis show that convergence of cell-wise BJ can degrade, leading to a spectral radius equal to 1, in problems containing optically thin cells. For problems containing cells that are optically thick, instead, the spectral radius tends to O. Hence, in the optically thick-cell regime, cell-wise BJ is rapidly convergent even for problems that are scattering dominated, with a scattering ratio c close to I.
Patterns of ventricular emptying by Fourier analysis of gated blood-pool studies
Links, J.M.; Douglass, K.H.; Wagner, H.N. Jr.
1980-10-01
Temporal Fourier analysis was applied to the processing of ECG-gated cardiac blood-pool studies on a pixel-by-pixel basis, to yield information about the pattern of ventricular emptying in normal hearts and in others with conduction abnormalities. The transform data at the fundamental frequency (the heart rate) were used to construct two types of display: (a) a distribution histogram of the pixel phase values, and (b) a cinematic display of the wave of emptying as it spread over the cardiac chambers. Preliminary results indicate that temporal Fourier analysis permits visualization of the pattern of ventricular emptying, which may prove useful in the study of motion abnormalities and asynergies, including those resulting from myocardial hypertrophy or conduction abnormalities, and as an aid in the optimum placement of pacemakers.
NASA Technical Reports Server (NTRS)
Deissler, Robert G.
1996-01-01
Background material on Fourier analysis and on the spectral form of the continuum equations, both averaged and unaveraged, are given. The equations are applied to a number of cases of homogeneous turbulence with and without mean gradients. Spectral transfer of turbulent activity between scales of motion is studied in some detail. The effects of mean shear, heat transfer, normal strain, and buoyancy are included in the analyses.
NASA Technical Reports Server (NTRS)
Powers, E. J.; Kim, Y. C.; Hong, J. Y.; Roth, J. R.; Krawczonek, W. M.
1978-01-01
A diagnostic, based on fast Fourier-transform spectral analysis techniques, that provides experimental insight into the relationship between the experimentally observable spectral characteristics of the fluctuations and the fluctuation-induced plasma transport is described. The model upon which the diagnostic technique is based and its experimental implementation is discussed. Some characteristic results obtained during the course of an experimental study of fluctuation-induced transport in the electric field dominated NASA Lewis bumpy torus plasma are presented.
Short time Fourier analysis of the electromyogram - Fast movements and constant contraction
NASA Technical Reports Server (NTRS)
Hannaford, Blake; Lehman, Steven
1986-01-01
Short-time Fourier analysis was applied to surface electromyograms (EMG) recorded during rapid movements, and during isometric contractions at constant forces. A portion of the data to be transformed by multiplying the signal by a Hamming window was selected, and then the discrete Fourier transform was computed. Shifting the window along the data record, a new spectrum was computed each 10 ms. The transformed data were displayed in spectograms or 'voiceprints'. This short-time technique made it possible to see time-dependencies in the EMG that are normally averaged in the Fourier analysis of these signals. Spectra of EMGs during isometric contractions at constant force vary in the short (10-20 ms) term. Short-time spectra from EMGs recorded during rapid movements were much less variable. The windowing technique picked out the typical 'three-burst pattern' in EMG's from both wrist and head movements. Spectra during the bursts were more consistent than those during isometric contractions. Furthermore, there was a consistent shift in spectral statistics in the course of the three bursts. Both the center frequency and the variance of the spectral energy distribution grew from the first burst to the second burst in the same muscle. The analogy between EMGs and speech signals is extended to argue for future applicability of short-time spectral analysis of EMG.
Measuring sperm movement within the female reproductive tract using Fourier analysis.
Nicovich, Philip R; Macartney, Erin L; Whan, Renee M; Crean, Angela J
2015-02-01
The adaptive significance of variation in sperm phenotype is still largely unknown, in part due to the difficulties of observing and measuring sperm movement in its natural, selective environment (i.e., within the female reproductive tract). Computer-assisted sperm analysis systems allow objective and accurate measurement of sperm velocity, but rely on being able to track individual sperm, and are therefore unable to measure sperm movement in species where sperm move in trains or bundles. Here we describe a newly developed computational method for measuring sperm movement using Fourier analysis to estimate sperm tail beat frequency. High-speed time-lapse videos of sperm movement within the female tract of the neriid fly Telostylinus angusticollis were recorded, and a map of beat frequencies generated by converting the periodic signal of an intensity versus time trace at each pixel to the frequency domain using the Fourier transform. We were able to detect small decreases in sperm tail beat frequency over time, indicating the method is sensitive enough to identify consistent differences in sperm movement. Fourier analysis can be applied to a wide range of species and contexts, and should therefore facilitate novel exploration of the causes and consequences of variation in sperm movement. PMID:25640702
NASA Technical Reports Server (NTRS)
Menenti, M.; Azzali, S.; Verhoef, W.; Van Swol, R.
1993-01-01
Examples are presented of applications of a fast Fourier transform algorithm to analyze time series of images of Normalized Difference Vegetation Index values. The results obtained for a case study on Zambia indicated that differences in vegetation development among map units of an existing agroclimatic map were not significant, while reliable differences were observed among the map units obtained using the Fourier analysis.
Analysis of moire fringes by Wiener filtering: An extension to the Fourier method
Harasse, Sebastien; Yashiro, Wataru; Momose, Atsushi
2012-07-31
In X-ray Talbot interferometry, tilting the phase grating with respect to the absorption grating results in the formation of spatial fringes. The analysis of this moire pattern, classically performed by the Fourier method, allows the extraction of the sample phase shift information from a single image. In this context, an extension to the Fourier method is proposed. The filter used to extract the fringe information is chosen optimally in the least-squares sense, given models for the zeroth and first order modes, noise and the modulation transfer function. The latter is obtained by measuring the detector response to moire fringes with increasing frequencies. The obtained Wiener filter allows a better reconstruction of the phase information at all fringe frequencies, compared to the usual box or gaussian filters. This is demonstrated quantitatively by experiments using synchrotron radiation.
Analysis of moiré fringes by Wiener filtering: An extension to the Fourier method
NASA Astrophysics Data System (ADS)
Harasse, Sébastien; Yashiro, Wataru; Momose, Atsushi
2012-07-01
In X-ray Talbot interferometry, tilting the phase grating with respect to the absorption grating results in the formation of spatial fringes. The analysis of this moiré pattern, classically performed by the Fourier method, allows the extraction of the sample phase shift information from a single image. In this context, an extension to the Fourier method is proposed. The filter used to extract the fringe information is chosen optimally in the least-squares sense, given models for the zeroth and first order modes, noise and the modulation transfer function. The latter is obtained by measuring the detector response to moiré fringes with increasing frequencies. The obtained Wiener filter allows a better reconstruction of the phase information at all fringe frequencies, compared to the usual box or gaussian filters. This is demonstrated quantitatively by experiments using synchrotron radiation.
NASA Astrophysics Data System (ADS)
Paul, Somnath; Tervo, Jani; Honakanen, Seppo
2014-05-01
We propose the Fourier Modal Method (FMM) as a convenient numerical tool for the design and analysis of nonlinear optical waveguides. The scope of this work includes the design of a polarization-independent nonlinear cross-slot waveguide for telecommunication applications at the wavelength of 1550 nm. The FMM method has been implemented, obeying the proper Fourier factorization rules, within a MATLABTM environment. The influence of the modal field intensity on the transverse refractive index distribution due to the optical Kerr effect is modeled with FMM for a propagation invariant scheme of the waveguide. The waveguide is geometrically optimized for an enhanced nonlinear light matter interaction. A silicon-inorganic hybrid material platform based on hydrogenated amorphous silicon (a-Si:H) and amorphous titanium dioxide (TiO2) is considered for the mentioned waveguide. With the optimized design of the waveguide, the achieved value of the nonlinear waveguide parameter (γ) is 4.678 × 104 W-1Km-1.
An application of the Fourier Series in the analysis of waterhammer in pumped storage plant
Serpas, D.
1995-12-31
In a pumped storage scheme, water flows from the upper reservoir to the lower reservoir, and the turbo/machine acts as turbine. In the pumping mode, the water is pumped from the lower reservoir to the upper reservoir, and the turbo/machine acts as a pump. A method using Fourier Series for the approximation of the characteristics curves of the pump in four quadrants is applied for the analysis of waterhammer due the power failure. Others conditions may also be analyzed. A program adjusts the data of the four characteristic curves in CHAUDRHY, 1987 by Fourier Series. This adjustment should permit a closer representation of the pump actually used in the system that will result in a more economical design.
Quantitative analysis of oils and fats by Fourier transform Raman spectroscopy
NASA Astrophysics Data System (ADS)
Sadeghi-Jorabchi, H.; Wilson, R. H.; Belton, P. S.; Edwards-Webb, J. D.; Coxon, D. T.
The rapid analysis of fats and oils is of great importance in the food industry. It is shown that Fourier transform Raman spectroscopy may be used for this purpose. Good quality spectra, free of fluorescence, may be obtained and the spectra may be interpreted in terms of changes in total unsaturation, cis/trans isomer ratios and the number of double bonds in the hydrocarbon chains. Quantitative analysis of total unsaturation and cis/trans is possible and offers considerable improvements in speed when compared with conventional methods.
NASA Astrophysics Data System (ADS)
Gokhale, M. H.
A spherical harmonic Fourier analysis of the maximum areas of sunspot groups listed in Ledgers I and II of Greenwich photoheliographic results for 1933 - 1954 yield significant peaks at the 11 y periodicity for some spherical harmonic modes: especially the mode (l = 6, m = 0). A similar analysis of the daily areas of the spotgroups during 1944 - 1954 yields 11 y periodicity peaks only for some non-axisymmetric modes. These results suggest that the sunspot activity may be physically related to long period global oscillations of the sun.
Spectral analysis comparisons of Fourier-theory-based methods and minimum variance (Capon) methods
NASA Astrophysics Data System (ADS)
Garbanzo-Salas, Marcial; Hocking, Wayne. K.
2015-09-01
In recent years, adaptive (data dependent) methods have been introduced into many areas where Fourier spectral analysis has traditionally been used. Although the data-dependent methods are often advanced as being superior to Fourier methods, they do require some finesse in choosing the order of the relevant filters. In performing comparisons, we have found some concerns about the mappings, particularly when related to cases involving many spectral lines or even continuous spectral signals. Using numerical simulations, several comparisons between Fourier transform procedures and minimum variance method (MVM) have been performed. For multiple frequency signals, the MVM resolves most of the frequency content only for filters that have more degrees of freedom than the number of distinct spectral lines in the signal. In the case of Gaussian spectral approximation, MVM will always underestimate the width, and can misappropriate the location of spectral line in some circumstances. Large filters can be used to improve results with multiple frequency signals, but are computationally inefficient. Significant biases can occur when using MVM to study spectral information or echo power from the atmosphere. Artifacts and artificial narrowing of turbulent layers is one such impact.
Siminoff, R
1991-01-01
Fourier analysis is used to study resolution of images processed by the matrix of simulated red-center (BCR) and green-center (BCG) bipolar cells (BC) of the human central fovea. Simulated achromatic and chromatic sine and square waves, and a two-bar stimulus are used to activate the BCs. Due to the "honeycomb" packing of the cones and BC matrices Fourier transforms are computed row by row using a one-dimensional FFT. Resolution computed by the Fourier transform is compared with the resolution index (RI), which is a method for determining resolution based on two-point discrimination in the space domain. In general the harmonic with the maximum amplitude gives the best correlation with RI for the three stimuli. Amplitudes at all spatial frequencies are enhanced by increasing the number of cycles in the sine and square wave gratings. Results with simulated BCs compare favorably with human and macaque psychophysics measuring contrast sensitivity. Square wave gratings are better than sine wave greetings for studying resolution. PMID:1768719
NASA Technical Reports Server (NTRS)
Eppler, D. T.; Nummedal, D.; Ehrlich, R.
1977-01-01
If the lithology of lunar crust influences impact crater morphology, a method of analysis that is sensitive to small-scale changes in crater shape is required. In the present paper, it is shown that Fourier analysis in closed form can provide detailed information regarding planimetric crater shape. Preliminary analysis of the rim crest outline of 247 nearside lunar craters (larger than 18 km in diam) led to the following information: Imbrian and pre-Imbrian craters are more elongate than younger craters, possibly as a result of widespread crustal deformation early in the moon's history. Crater size does not affect the planimetric shape of craters. Highland craters are less circular than mare craters, probably due to the greater structural and lithologic complexity of the highland crust. Craters comprising each shape family of the eleventh harmonic typically are located in the same general geographic region of the moon.
Fourier transform infrared spectroscopy techniques for the analysis of drugs of abuse
NASA Astrophysics Data System (ADS)
Kalasinsky, Kathryn S.; Levine, Barry K.; Smith, Michael L.; Magluilo, Joseph J.; Schaefer, Teresa
1994-01-01
Cryogenic deposition techniques for Gas Chromatography/Fourier Transform Infrared (GC/FT-IR) can be successfully employed in urinalysis for drugs of abuse with detection limits comparable to those of the established Gas Chromatography/Mass Spectrometry (GC/MS) technique. The additional confidence of the data that infrared analysis can offer has been helpful in identifying ambiguous results, particularly, in the case of amphetamines where drugs of abuse can be confused with over-the-counter medications or naturally occurring amines. Hair analysis has been important in drug testing when adulteration of urine samples has been a question. Functional group mapping can further assist the analysis and track drug use versus time.
Assessment of vasomotor oscillations with Fourier analysis of biological tissue impedance
NASA Astrophysics Data System (ADS)
Nesterov, A.; Gavrilov, I.; Selector, L.; Mudraya, I.; Revenko, S.
2010-04-01
Fourier analysis revealed a number of periodicities in small variations of bioimpedance of human finger including the major spectrum peaks at the frequencies of heart beats, respiration, and Mayer wave (0.1 Hz). These periodic variations of bioimpedance were detected under the normal conditions and during blood flow arrest in the hand by a pneumatic cuff placed on the arm. They are explained by periodic variations in systemic blood pressure and by oscillations of regional vascular tone resulted from neural vasomotor control. During normal blood flow, the greatest variations in bioimpedance were observed at the heart rate, and their amplitude surpassed by an order of magnitude the amplitudes of respiratory oscillations and Mayer wave. In contrast, during blood arrest, the largest amplitude of rhythmical changes of the impedance characterized the oscillations at respiration rate, while the amplitude of oscillations at the heart rate was the smallest. During normal respiration and circulation, two side cardiac peaks were revealed in bioimpedance amplitude spectrum which disappeared during respiration arrest and thought to reflect the amplitude respiratory modulation of the cardiac output via sympathetic influences. During normal breathing, the second and the third harmonics of the cardiac spectrum peak were split reflecting frequency respiratory modulation of the heart rate by parasympathetic influences. The results favour applicability of Fourier analysis of bioimpedance variations in assessment of regional neural influences and neurogenic modulation of cardiac activity.
NASA Astrophysics Data System (ADS)
Dai, Xianglu; Xie, Huimin; Wang, Qinghua
2014-06-01
The geometric phase analysis (GPA), an important image-based deformation measurement method, has been used at both micro- and nano-scale. However, when a deformed image has apparent distortion, non-ignorable error in the obtained deformation field could occur by using this method. In this paper, the geometric phase analysis based on the windowed Fourier transform (WFT) is proposed to solve the above-mentioned issue, defined as the WFT-GPA method. In WFT-GPA, instead of the Fourier transform (FT), the WFT is utilized to extract the phase field block by block, and therefore more accurate local phase information can be acquired. The simulation tests, which include detailed discussion of influence factors for measurement accuracy such as window size and image noise, are conducted with digital deformed grids. The results verify that the WFT-GPA method not only keeps all advantages of traditional GPA method, but also owns a better accuracy for deformation measurement. Finally, the WFT-GPA method is applied to measure the machining distortion incurred in soft ultraviolet nanoimprint lithography (UV-NIL) process. The successful measurement shows the feasibility of this method and offers a full-field way for characterizing the replication quality of UV-NIL process.
Thompson, Sandra E.; Foster, Nancy S.; Johnson, Timothy J.; Valentine, Nancy B.; Amonette, James E.
2003-08-28
Fourier Transform Infrared Photoacoustic Spectroscopy (FTIR-PAS) has been applied for the first time to the identification and speciation of bacterial spores. With minimal preparation the spores were deposited into the photoacoustic sample cup and their spectra recorded. A total of 40 different samples of 5 different strains of Bacillus spores were analyzed: Bacillus subtilis ATCC 49760, Bacillus atrophaeus ATCC 49337, Bacillus subtilis 6051, Bacillus thuringiensis ssp. kurstaki, and Bacillus globigii Dugway. The statistical methods used included principal-component analysis (PCA), classification and regression trees (CART), and Mahalanobis-distance calculations. Internal cross-validation studies successfully classify the spores according to their bacterial strain in 38 of 40 cases (95%) and 36 of 40 (90%) in cross-validation. Analysis of fifteen blind samples, which included library and other spores, and nonbacterial materials, resulted in correct strain classification the blind samples that were members of the library and correct rejection of the nonbacterial samples.
Requirements Formulation and Dynamic Jitter Analysis for Fourier-Kelvin Stellar Interferometer
NASA Technical Reports Server (NTRS)
Liu, Kuo-Chia; Hyde, Tristram; Blaurock, Carl; Bolognese, Jeff; Howard, Joseph; Danchi, William
2004-01-01
The Fourier-Kelvin Stellar Interferometer (FKSI) has been proposed to detect and characterize extra solar giant planets. The baseline configuration for FKSI is a two- aperture, structurally connected nulling interferometer, capable of providing null depth less than lo4 in the infrared. The objective of this paper is to summarize the process for setting the top level requirements and the jitter analysis performed on FKSI to date. The first part of the paper discusses the derivation of dynamic stability requirements, necessary for meeting the FKSI nulling demands. An integrated model including structures, optics, and control systems has been developed to support dynamic jitter analysis and requirements verification. The second part of the paper describes how the integrated model is used to investigate the effects of reaction wheel disturbances on pointing and optical path difference stabilities.
Quantitative Fourier transform infrared analysis of gas phase cigarette smoke and other gas mixtures
Cueto, R.; Church, D.F.; Pryor, W.A. )
1989-03-01
A new method for the analysis of selected components in complex gas mixtures has been developed utilizing a relatively inexpensive Fourier transform infrared spectrometer and a continuous flow gas cell. The method was used to monitor nitric oxide and nitrogen dioxide concentrations in cigarette smoke with time. Using multivariate least-square regression analysis, it is possible to simultaneously quantitate both NO and NO{sub 2}, even in the presence of overlapping peaks. Using this method, the oxidation of nitric oxide in the presence of isoprene in cigarette smoke and in a model system was followed with time. The method also can be applied to other compounds in smoke or to any other gaseous mixture.
Zhang, Yong; Cao, Chun-yu; Feng, Wen-ying; Xu, Ming; Su, Zhen-hua; Liu, Xiao-meng; Lü, Wei-jun
2011-03-01
As one of the most powerful tools to investigate the compositions of raw materials and the property of pulp and paper, infrared spectroscopy has played an important role in pulp and paper industry. However, the traditional transmission infrared spectroscopy has not met the requirements of the producing processes because of its disadvantages of time consuming and sample destruction. New technique would be needed to be found. Fourier transform attenuated total reflection infrared spectroscopy (ATR-FTIR) is an advanced spectroscopic tool for nondestructive evaluation and could rapidly, accurately estimate the production properties of each process in pulp and paper industry. The present review describes the application of ATR-FTIR in analysis of pulp and paper industry. The analysis processes will include: pulping, papermaking, environmental protecting, special processing and paper identifying. PMID:21595211
Assis, A C Almeida; Barbosa, M F; Nabais, J M Valente; Custódio, A F; Tropecelo, P
2012-01-10
This paper describes the use of a diamond cell Fourier transform infrared (FTIR) spectroscopy methodology for the analysis of black toners commercialised in Portugal. A total of one hundred and thirty-eight samples from eighteen manufacturers were analysed in transmittance mode through a diamond cell. This methodology was considered to be non-destructive as it allows the forensic analysis of the questioned documents while preserving their integrity. The questioned documents' substrate (paper sheets) has no influence on the final result. This technique shows high repeatability and intermediate precision. Spectra were organized in twenty distinct groups based on their main chemical characteristics and relative peak intensity; and a black toner infrared spectral library was developed. Spectral matches between forty-five blind samples and the database resulted in a 100% positive identification to the correct group. PMID:21831548
Measurement of absolute optical thickness of mask glass by wavelength-tuning Fourier analysis.
Kim, Yangjin; Hbino, Kenichi; Sugita, Naohiko; Mitsuishi, Mamoru
2015-07-01
Optical thickness is a fundamental characteristic of an optical component. A measurement method combining discrete Fourier-transform (DFT) analysis and a phase-shifting technique gives an appropriate value for the absolute optical thickness of a transparent plate. However, there is a systematic error caused by the nonlinearity of the phase-shifting technique. In this research the absolute optical-thickness distribution of mask blank glass was measured using DFT and wavelength-tuning Fizeau interferometry without using sensitive phase-shifting techniques. The error occurring during the DFT analysis was compensated for by using the unwrapping correlation. The experimental results indicated that the absolute optical thickness of mask glass was measured with an accuracy of 5 nm. PMID:26125394
Fourier mode analysis of slab-geometry transport iterations in spatially periodic media
Larsen, E W; Zika, M R
1999-05-07
We describe a Fourier analysis of the diffusion-synthetic acceleration (DSA) and transport-synthetic acceleration (TSA) iteration schemes for a spatially periodic, but otherwise arbitrarily heterogeneous, medium. Both DSA and TSA converge more slowly in a heterogeneous medium than in a homogeneous medium composed of the volume-averaged scattering ratio. In the limit of a homogeneous medium, our heterogeneous analysis contains eigenvalues of multiplicity two at ''resonant'' wave numbers. In the presence of material heterogeneities, error modes corresponding to these resonant wave numbers are ''excited'' more than other error modes. For DSA and TSA, the iteration spectral radius may occur at these resonant wave numbers, in which case the material heterogeneities most strongly affect iterative performance.
Fourier mode analysis of slab-geometry transport iterations in spatially periodic media
Larsen, E; Zika, M
1999-04-01
We describe a Fourier analysis of the diffusion-synthetic acceleration (DSA) and transport-synthetic acceleration (TSA) iteration schemes for a spatially periodic, but otherwise arbitrarily heterogeneous, medium. Both DSA and TSA converge more slowly in a heterogeneous medium than in a homogeneous medium composed of the volume-averaged scattering ratio. In the limit of a homogeneous medium, our heterogeneous analysis contains eigenvalues of multiplicity two at ''resonant'' wave numbers. In the presence of material heterogeneities, error modes corresponding to these resonant wave numbers are ''excited'' more than other error modes. For DSA and TSA, the iteration spectral radius may occur at these resonant wave numbers, in which case the material heterogeneities most strongly affect iterative performance.
Murali, S; Vladimir, Kulish V
2007-10-01
Fast Fourier transform (FFT) and fractal dimension (FD) are computed to discover the evoked potentials (EPs) in the base human electroencephalograms (EEGs) corresponding to six types of odor inhalation, one at a time. During the first 20 s of the EEG recording, the patient breathes normally and the rest of the recording time 21-64 s, inhales an odor, when both the eye open and closed modes. FFT spectral analysis cannot discriminate the potential due to olfactory stimuli from the base EEG. However, fractal spectra analysis predicts the evoked potential due to inhalation of English rose, jasmine, lemon, orange, rose garden, and sandalwood concentrates. Similar results are obtained for three of the patients examined and on computing for five EEG recordings of two patients during inhalation of six types of odor. PMID:17729151
Rosa, M.; Warsa, J. S.; Chang, J. H.
2006-07-01
A Fourier analysis is conducted for the discrete-ordinates (SN) approximation of the neutron transport problem solved with Richardson iteration (Source Iteration) and Richardson iteration preconditioned with Transport Synthetic Acceleration (TSA), using the Parallel Block-Jacobi (PBJ) algorithm. Both 'traditional' TSA (TTSA) and a 'modified' TSA (MTSA), in which only the scattering in the low order equations is reduced by some non-negative factor {beta} and < 1, are considered. The results for the un-accelerated algorithm show that convergence of the PBJ algorithm can degrade. The PBJ algorithm with TTSA can be effective provided the {beta} parameter is properly tuned for a given scattering ratio c, but is potentially unstable. Compared to TTSA, MTSA is less sensitive to the choice of {beta}, more effective for the same computational effort (c'), and it is unconditionally stable. (authors)
NASA Astrophysics Data System (ADS)
Chen, Cheng; Liang, Jingqiu; Liang, Zhongzhu; Lü, Jinguang; Qin, Yuxin; Tian, Chao; Wang, Weibiao
2015-12-01
A method of "slope splicing" is proposed to build a tall-stepped mirror with high precision in a stepped-mirror-based static Fourier transform infrared spectrometer. The structural parameters were designed, and their errors were analyzed. We present the test results and an analysis of the combined effect of the errors on the recovered spectrum. The spectrum-constructing error of the constructed spectrum, 5.81%, meets the requirements for the system and suitable for realization of a miniaturized spectrometer. We performed experiments with the tall-stepped mirror to obtain the interferogram and spectrum of a silicon carbide light source. Further work is needed to optimize the capability of the system.
Visser, T; Vredenbregt, M J; de Jong, A P; van Rossum, H J; Stephany, R W; van Ginkel, L A
1994-12-01
Cryotrapping gas chromatography-Fourier transform infrared spectrometry has been used for confirmation analysis of the beta-agonists clenbuterol, salbutamol, mabuterol, bromobuterol, cimaterol, cimbuterol and mapenterol in urine and liver samples of veal calves, subsequent to selected ion detection gas chromatography-mass spectrometry. Samples have been analysed as their trimethylsilyl and methylboronate derivatives. Methylboronate derivatives yielded strongly diminished chemical background and interference levels in the infrared chromatograms of standards and samples. The limit of identification for methylboronate derivatives was at the low ppb level in incurred samples. The similarity of analyte and reference spectra, together with the retention time, was found to be a useful criterion for confirmation of unknown compounds. PMID:7879875
Zhang, Xiaoxing; Liu, Heng; Ren, Jiangbo; Li, Jian; Li, Xin
2015-02-01
Gas-insulated switchgear (GIS) internal SF6 gas produces specific decomposition components under partial discharge (PD). By detecting these characteristic decomposition components, such information as the type and level of GIS internal insulation deterioration can be obtained effectively, and the status of GIS internal insulation can be evaluated. SF6 was selected as the background gas for Fourier transform infrared spectroscopy (FTIR) detection in this study. SOF2, SO2F2, SO2, and CO were selected as the characteristic decomposition components for system analysis. The standard infrared absorption spectroscopy of the four characteristic components was measured, the optimal absorption peaks were recorded and the corresponding absorption coefficient was calculated. Quantitative detection experiments on the four characteristic components were conducted. The volume fraction variation trend of four characteristic components at different PD time were analyzed. And under five different PD quantity, the quantitative relationships among gas production rate, PD time, and PD quantity were studied. PMID:25459612
NASA Astrophysics Data System (ADS)
Zhang, Xiaoxing; Liu, Heng; Ren, Jiangbo; Li, Jian; Li, Xin
2015-02-01
Gas-insulated switchgear (GIS) internal SF6 gas produces specific decomposition components under partial discharge (PD). By detecting these characteristic decomposition components, such information as the type and level of GIS internal insulation deterioration can be obtained effectively, and the status of GIS internal insulation can be evaluated. SF6 was selected as the background gas for Fourier transform infrared spectroscopy (FTIR) detection in this study. SOF2, SO2F2, SO2, and CO were selected as the characteristic decomposition components for system analysis. The standard infrared absorption spectroscopy of the four characteristic components was measured, the optimal absorption peaks were recorded and the corresponding absorption coefficient was calculated. Quantitative detection experiments on the four characteristic components were conducted. The volume fraction variation trend of four characteristic components at different PD time were analyzed. And under five different PD quantity, the quantitative relationships among gas production rate, PD time, and PD quantity were studied.
NASA Astrophysics Data System (ADS)
Nosi, D.; Delfino, G.; Quercioli, F.
2013-03-01
A combined transmission electron microscopy (TEM) and Fourier transform analysis has been performed on the secretory granules storing active peptides/proteins in serous cutaneous glands of n = 12 anuran species. Previous TEM investigation showed that the granules are provided with remarkable repeating substructures based on discrete subunits, arranged into a consistent framework. Furthermore, TEM findings revealed that this recurrent arrangement is acquired during a prolonged post-Golgian (or maturational) processing that affects the secretory product. Maturation leads to a variety of patterns depending on the degree of subunit clustering. This variety of recurrent patterns has been plotted into a range of frequency spectra. Through this quantitative approach, we found that the varying granule substructure can be reduced to a single mechanism of peptide/protein aggregation.
Single frame method for resolution enhancement of the Fourier fringe analysis method
NASA Astrophysics Data System (ADS)
Tavares, Paulo J.; Vaz, Mário A. P.
2013-11-01
Fourier Transform Profilometry (FTP) is one of the most popular fringe analysis methods in Optical Metrology for a wealth of applications in Mechanical Engineering, such as shape profilometry or defect detection with shearography or holographic interferometry methods. Gradient range and spatial resolution in the FTP method depend on the size of the filter window in reciprocal space. The authors have previously reported on a method that uses a single crossed fringe pattern for the elimination of the fundamental frequency and enlargement of the carrier window, which is therefore inherently able to cope with dynamic situations. This article describes an improved version of the technique that no longer resources to bit-shifting operations, greatly improving the flexibility of the previously reported technique, whilst retaining its main advantages.
Fast Fourier transform analysis of sounds made while swallowing various foods.
Taniwaki, Mitsuru; Kohyama, Kaoru
2012-10-01
The cervical auscultation method was applied to investigate sounds generated while swallowing various foods with unique physical properties, including liquid (water), semiliquid (yogurt), and solid (konjac jelly). To study the differences among swallowing sounds for various foods, fast Fourier transform (FFT) analysis was applied to signals that were attributed to the flow of a food bolus, which is a swallowable soft mass of chewed food. An FFT program was developed that enabled the calculation of a spectrum for a specified region of time domain swallowing sound signals. The intensity of spectra in the frequency range between 400 and 1000 Hz significantly differed: liquid > semiliquid > solid. The FFT spectrum in this range was suggested to represent the frequency characteristics of the swallowing sounds of various foods. PMID:23039442
Principal component analysis based carrier removal approach for Fourier transform profilometry
NASA Astrophysics Data System (ADS)
Feng, Shijie; Chen, Qian; Zuo, Chao
2015-05-01
To handle the issue of the nonlinear carrier phase due to the divergent illumination commonly adopted in the fringe projection measurement, we propose a principal component analysis (PCA) based carrier removal method for Fourier transform profilometry. By PCA, the method can decompose the nonlinear carrier phase map into several principal components, where the phase of the carrier can be extracted from the first dominant component acquired. It is effective and requires less human intervention since no data points need to be collected from the reference plane in advance compared with traditional methods. Further, the influence of the lens distortion is considered thus the carrier can be determined more accurately. Our experiment shows the validity of the proposed approach.
Neichel, Benoit; Fusco, Thierry; Conan, Jean-Marc
2009-01-01
Several wide-field-of-view adaptive optics (WFAO) concepts such as multi-conjugate AO (MCAO), multi-object AO (MOAO), and ground-layer AO (GLAO) are currently being studied for the next generation of Extremely Large Telescopes (ELTs). All these concepts will use atmospheric tomography to reconstruct the turbulent-phase volume. In this paper, we explore different reconstruction algorithms and their fundamental limitations, conducting this analysis in the Fourier domain. This approach allows us to derive simple analytical formulations for the different configurations and brings a comprehensive view of WFAO limitations. We then investigate model and statistical errors and their effect on the phase reconstruction. Finally, we show some examples of different WFAO systems and their expected performance on a 42 m telescope case. PMID:19109619
Verification of the helioseismic Fourier-Legendre analysis for meridional flow measurements
NASA Astrophysics Data System (ADS)
Roth, M.; Doerr, H.-P.; Hartlep, T.
2016-08-01
Context. Measuring the Sun's internal meridional flow is one of the key issues of helioseismology. Using the Fourier-Legendre analysis is a technique for addressing this problem. Aims: We validate this technique with the help of artificial helioseismic data. Methods: The analysed data set was obtained by numerically simulating the effect of the meridional flow on the seismic wave field in the full volume of the Sun. In this way, a 51.2-h long time series was generated. The resulting surface velocity field is then analyzed in various settings: Two 360° × 90° halfspheres, two 120° × 60° patches on the front and farside of the Sun (North and South, respectively) and two 120° × 60° patches on the northern and southern frontside only. We compare two possible measurement setups: observations from Earth and from an additional spacecraft on the solar farside, and observations from Earth only, in which case the full information of the global solar oscillation wave field was available. Results: We find that, with decreasing observing area, the accessible depth range decreases: the 360° × 90° view allows us to probe the meridional flow almost to the bottom of the convection zone, while the 120° × 60° view means only the outer layers can be probed. Conclusions: These results confirm the validity of the Fourier-Legendre analysis technique for helioseismology of the meridional flow. Furthermore these flows are of special interest for missions like Solar Orbiter that promises to complement standard helioseismic measurements from the solar nearside with farside observations.
NASA Astrophysics Data System (ADS)
Brzezinski, A.
2014-12-01
The methods of spectral analysis are applied to solve the following two problems concerning the free Chandler wobble (CW): 1) to estimate the CW resonance parameters, the period T and the quality factor Q, and 2) to perform the excitation balance of the observed free wobble. It appears, however, that the results depend on the algorithm of spectral analysis applied. Here we compare the following two algorithms which are frequently applied for analysis of the polar motion data, the classical discrete Fourier analysis and the maximum entropy method corresponding to the autoregressive modeling of the input time series. We start from general description of both methods and of their application to the analysis of the Earth orientation observations. Then we compare results of the analysis of the polar motion and the related excitation data.
Sanfilippo, P.G.; Grimm, J.L.; Flanagan, J.G.; Lathrop, K.L.; Sigal, I.A.
2014-01-01
The lamina cribrosa (LC) plays an important biomechanical role in the optic nerve head (ONH). We developed a statistical shape model of the LC and tested if the shape varies with age or IOP. The ONHs of 18 donor eyes (47 to 91 years, mean 76 years) fixed at either 5 or 50 mm Hg of IOP were sectioned, stained, and imaged under a microscope. A 3D model of each ONH was reconstructed and the outline of the vertical sagittal section closest to the geometric centre of the LC extracted. The outline shape was described using elliptic Fourier analysis, and principal components analysis (PCA) employed to identify the primary modes of LC shape variation. Linear mixed effect models were used to determine if the shape measurements were associated with age or IOP. The analysis revealed several modes of shape variation: thickness and depth directly (PC1), or inversely (PC2) related, and superior-inferior asymmetry (PC3). Only PC3 was associated with IOP, with higher IOP correlating with greater curvature of the LC superiorly compared to inferiorly. Our analysis enabled a concise and complete characterization of LC shape, revealing variations without defining them a priori. No association between LC shape and age was found for the relatively old population studied. Superior-inferior asymmetry of LC shape was associated with IOP, with more asymmetry at higher IOP. Increased IOP was not associated with LC thickness or depth. PMID:25193035
Rajačić, M M; Todorović, D J; Krneta Nikolić, J D; Janković, M M; Djurdjević, V S
2016-09-01
Air sample monitoring in Serbia, Belgrade started in the 1960s, while (7)Be activity in air and total (dry and wet) deposition has been monitored for the last 22 years by the Environment and Radiation Protection Department of the Institute for Nuclear Sciences, Vinca. Using this data collection, the changes of the (7)Be activity in the air and the total (wet and dry) deposition samples, as well as their correlation with meteorological parameters (temperature, pressure, cloudiness, sunshine duration, precipitation and humidity) that affect (7)Be concentration in the atmosphere, were mathematically described using the Fourier analysis. Fourier analysis confirmed the expected; the frequency with the largest intensity in the harmonic spectra of the (7)Be activity corresponds to a period of 1 year, the same as the largest intensity frequency in Fourier series of meteorological parameters. To analyze the quality of the results produced by the Fourier analysis, we compared the measured values of the parameters with the values calculated according to the Fourier series. Absolute deviations between measured and predicted mean monthly values are in range from 0.02 mBq/m(3) to 0.7 mBq/m(3) for (7)Be activity in air, and 0.01 Bq/m(2) and 0.6 Bq/m(2) for (7)Be activity in deposition samples. Relatively good agreement of measured and predicted results offers the possibility of prediction of the (7)Be activity. PMID:27396670
Childs, Paul; Wong, Allan C. L.; Fu, H. Y.; Liao, Yanbiao; Tam, Hwayaw; Lu Chao; Wai, P. K. A.
2010-12-20
.We measured the hydrostatic pressure dependence of the birefringence and birefringent dispersion of a Sagnac interferometric sensor incorporating a length of highly birefringent photonic crystal fiber using Fourier analysis. Sensitivity of both the phase and chirp spectra to hydrostatic pressure is demonstrated. Using this analysis, phase-based measurements showed a good linearity with an effective sensitivity of 9.45nm/MPa and an accuracy of {+-}7.8kPa using wavelength-encoded data and an effective sensitivity of -55.7cm{sup -1}/MPa and an accuracy of {+-}4.4kPa using wavenumber-encoded data. Chirp-based measurements, though nonlinear in response, showed an improvement in accuracy at certain pressure ranges with an accuracy of {+-}5.5kPa for the full range of measured pressures using wavelength-encoded data and dropping to within {+-}2.5kPa in the range of 0.17 to 0.4MPa using wavenumber-encoded data. Improvements of the accuracy demonstrated the usefulness of implementing chirp-based analysis for sensing purposes.
NASA Astrophysics Data System (ADS)
Bej, Subhajit; Tervo, Jani; Francés, Jorge; Svirko, Yuri P.; Turunen, Jari
2016-05-01
We propose the nonlinear Fourier Modal Method (FMM) [J. Opt. Soc. Am. B 31, 2371 (2014)] as a convenient and versatile numerical tool for the design and analysis of grating based next generation all-optical devices. Here, we include several numerical examples where the FMM is used to simulate all-optically tunable functionalities in sub-wavelength periodic structures. At first, we numerically investigate a 1-D periodic nonlinear binary grating with amorphous TiO2. We plot the diffraction efficiency in the transmitted orders against the structure depth for normally incident plane wave. Change in diffraction efficiencies for different incident field amplitudes are evident from the plots. We verify the accuracy of our implementation by comparing our results with the results obtained with the nonlinear Split Field-Finite Difference Time Domain (SF-FDTD) method. Next we repeat the same experiment with vertically standing amorphous Titanium dioxide (TiO2) nanowire arrays grown on top of quartz which are periodic in two mutually perpendicular directions and examine the efficiencies in the direct transmitted light for different incident field amplitudes. Our third example includes analysis of a form birefringent linear grating with Kerr medium. With FMM we demonstrate that the birefringence of such a structure can be tuned by all-optical means. As a final example, we design a narrow band Guided Mode Resonance Filter (GMRF). Numerical experiments based on the nonlinear FMM reveal that the spectral tunability of such a filter can be obtained by all-optical means.
NASA Astrophysics Data System (ADS)
Williams, Anthony; Chung, Jaebum; Ou, Xiaoze; Zheng, Guoan; Rawal, Siddarth; Ao, Zheng; Datar, Ram; Yang, Changhuei; Cote, Richard
2014-06-01
Circulating tumor cells (CTCs) are recognized as a candidate biomarker with strong prognostic and predictive potential in metastatic disease. Filtration-based enrichment technologies have been used for CTC characterization, and our group has previously developed a membrane microfilter device that demonstrates efficacy in model systems and clinical blood samples. However, uneven filtration surfaces make the use of standard microscopic techniques a difficult task, limiting the performance of automated imaging using commercially available technologies. Here, we report the use of Fourier ptychographic microscopy (FPM) to tackle this challenge. Employing this method, we were able to obtain high-resolution color images, including amplitude and phase, of the microfilter samples over large areas. FPM's ability to perform digital refocusing on complex images is particularly useful in this setting as, in contrast to other imaging platforms, we can focus samples on multiple focal planes within the same frame despite surface unevenness. In model systems, FPM demonstrates high image quality, efficiency, and consistency in detection of tumor cells when comparing corresponding microfilter samples to standard microscopy with high correlation (R2=0.99932). Based on these results, we believe that FPM will have important implications for improved, high throughput, filtration-based CTC analysis, and, more generally, image analysis of uneven surfaces.
Anderson, Timothy J.; Ai, Yongfeng; Jones, Roger W.; Houk, Robert S.; Jane, Jay-lin; Zhao, Yinsheng; Birt, Diane F.; McClelland, John F.
2013-01-29
Fourier transform infrared photoacoustic spectroscopy (FTIR-PAS) qualitatively and quantitatively measured resistant starch (RS) in rat cecal contents. Fisher 344 rats were fed diets of 55% (w/w, dry basis) starch for 8 weeks. Cecal contents were collected from sacrificed rats. A corn starch control was compared against three RS diets. The RS diets were high-amylose corn starch (HA7), HA7 chemically modified with octenyl succinic anhydride, and stearic-acid-complexed HA7 starch. To calibrate the FTIR-PAS analysis, samples from each diet were analyzed using an enzymatic assay. A partial least-squares cross-validation plot generated from the enzymatic assay and FTIR-PAS spectral results for starch fit the ideal curve with a R2 of 0.997. A principal component analysis plot of components 1 and 2 showed that spectra from diets clustered significantly from each other. This study clearly showed that FTIR-PAS can accurately quantify starch content and identify the form of starch in complex matrices.
Williams, Anthony; Chung, Jaebum; Ou, Xiaoze; Zheng, Guoan; Rawal, Siddarth; Ao, Zheng; Datar, Ram; Yang, Changhuei; Cote, Richard
2014-01-01
Abstract. Circulating tumor cells (CTCs) are recognized as a candidate biomarker with strong prognostic and predictive potential in metastatic disease. Filtration-based enrichment technologies have been used for CTC characterization, and our group has previously developed a membrane microfilter device that demonstrates efficacy in model systems and clinical blood samples. However, uneven filtration surfaces make the use of standard microscopic techniques a difficult task, limiting the performance of automated imaging using commercially available technologies. Here, we report the use of Fourier ptychographic microscopy (FPM) to tackle this challenge. Employing this method, we were able to obtain high-resolution color images, including amplitude and phase, of the microfilter samples over large areas. FPM’s ability to perform digital refocusing on complex images is particularly useful in this setting as, in contrast to other imaging platforms, we can focus samples on multiple focal planes within the same frame despite surface unevenness. In model systems, FPM demonstrates high image quality, efficiency, and consistency in detection of tumor cells when comparing corresponding microfilter samples to standard microscopy with high correlation (R2=0.99932). Based on these results, we believe that FPM will have important implications for improved, high throughput, filtration-based CTC analysis, and, more generally, image analysis of uneven surfaces. PMID:24949708
Mao, Zhi-Hua; Yin, Jian-Hua; Zhang, Xue-Xi; Wang, Xiao; Xia, Yang
2016-02-01
Fourier transform infrared spectroscopic imaging (FTIRI) technique can be used to obtain the quantitative information of content and spatial distribution of principal components in cartilage by combining with chemometrics methods. In this study, FTIRI combining with principal component analysis (PCA) and Fisher's discriminant analysis (FDA) was applied to identify the healthy and osteoarthritic (OA) articular cartilage samples. Ten 10-μm thick sections of canine cartilages were imaged at 6.25μm/pixel in FTIRI. The infrared spectra extracted from the FTIR images were imported into SPSS software for PCA and FDA. Based on the PCA result of 2 principal components, the healthy and OA cartilage samples were effectively discriminated by the FDA with high accuracy of 94% for the initial samples (training set) and cross validation, as well as 86.67% for the prediction group. The study showed that cartilage degeneration became gradually weak with the increase of the depth. FTIRI combined with chemometrics may become an effective method for distinguishing healthy and OA cartilages in future. PMID:26977354
NASA Astrophysics Data System (ADS)
von Aulock, F. W.; Kennedy, B. M.; Schipper, C. I.; Castro, J. M.; Martin, D. E.; Oze, C.; Watkins, J. M.; Wallace, P. J.; Puskar, L.; Bégué, F.; Nichols, A. R. L.; Tuffen, H.
2014-10-01
Fourier transform infrared spectroscopy (FTIR) is an analytical technique utilized to measure the concentrations of H and C species in volcanic glasses. Water and CO2 are the most abundant volatile species in volcanic systems. Water is present in magmas in higher concentrations than CO2 and is also more soluble at lower pressures, and, therefore it is the dominant volatile forming bubbles during volcanic eruptions. Dissolved water affects both phase equilibria and melt physical properties such as density and viscosity, therefore, water is important for understanding magmatic processes. Additionally, quantitative measurements of different volatile species using FTIR can be achieved at high spatial resolution. Recent developments in analytical equipment such as synchrotron light sources and the development of focal plane array (FPA) detectors allow higher resolution measurements and the acquisition of concentration maps. These new capabilities are being used to characterize spatial gradients (or lack thereof) around bubbles and other textural features, which in turn lead to new insights into the behavior of volcanic feeder systems. Here, practical insights about sample preparation and analysis of the distribution and speciation of volatiles in volcanic glasses using FTIR spectroscopy are discussed. New advances in the field of FTIR analysis produce reliable data at high spatial resolution that can be used to produce datasets on the distribution, dissolution and diffusion of volatiles in volcanic materials.
NASA Astrophysics Data System (ADS)
Suriyawichitseranee, A.; Grigoriev, Yu. N.; Meleshko, S. V.
2015-03-01
The paper is devoted to group analysis of the spatially homogeneous and isotropic Boltzmann equation with a source term. In fact, the Fourier transform of the Boltzmann equation with respect to the molecular velocity variable is considered. Using a particular class of solutions, the determining equation for the admitted Lie group is reduced to a partial differential equation for the source function. The latter equation is analyzed by an algebraic method. A complete group classification of the Fourier transform of the Boltzmann equation is given. All invariant solutions of this equation are also presented in the paper.
NASA Astrophysics Data System (ADS)
Grigoriev, Yurii N.; Meleshko, Sergey V.; Suriyawichitseranee, Amornrat
2015-06-01
Group analysis of the spatially homogeneous and molecular energy dependent Boltzmann equations with source term is carried out. The Fourier transform of the Boltzmann equation with respect to the molecular velocity variable is considered. The correspondent determining equation of the admitted Lie group is reduced to a partial differential equation for the admitted source. The latter equation is analyzed by an algebraic method. A complete group classification of the Fourier transform of the Boltzmann equation with respect to a source function is given. The representation of invariant solutions and corresponding reduced equations for all obtained source functions are also presented.
Technology Transfer Automated Retrieval System (TEKTRAN)
Although grain shape is an important cereal breeding target, it has been evaluated using simple measurements, e.g. the length : width ratio. We used elliptic Fourier analysis to evaluate grain shape variation and conducted whole genome association mapping of grain shape using a germplasm collectio...
NASA Astrophysics Data System (ADS)
Loos, Joep; Birk, Manfred; Wagner, Georg
2014-06-01
A new fitting tool written in IDL for analysis of single or multiple molecular absorption spectra recorded with a Fourier-transform spectrometer will be presented. The software utilizes a microwindow-based line-by-line approach and its capabilities include the choice of numerous different line-shape models, from a simple Voigt to more sophisticated models including e.g. speed-dependence, Dicke narrowing or Rosenkranz line mixing. A comfortable interactive mode as well as a fully automatic mode have been implemented including various quality assessment procedures like the monitoring of correlation coefficients or the supply of useful information e.g. needed for file cuts (single spectrum residuals). Two application examples will be given as illustration of the software's capabilities. First, the results of a speed-dependent analysis of room temperature water vapor spectra in the 1250-1750 cm-1 range are compared to the original results obtained by an analysis based on single spectra fits applying the Voigt procedure. The results of the new approach show significantly reduced residuals and systematically larger broadening parameters. The so far published Voigt broadening parameters are effective parameters being systematically too small since they compensate narrowing. Usually effective Voigt parameters are retrieved from non-opaque lines and should only be used when modelling non-opaque lines. Second, the results of an analysis of air broadened nitrous oxide spectra in the ν3 rovibrational band utilizing the pCqSDHC model1 including first order line mixing will be presented. Speed dependence of the broadening parameter as well as line mixing have to be considered in order to represent the spectral features down to the 0.1% level.
Moffat, Jonathan G; Mayes, Andrew G; Belton, Peter S; Craig, Duncan Q M; Reading, Mike
2010-01-01
Photothermal-Fourier transform-infrared (PT-FT-IR) microspectroscopy employs a thermal probe mounted in a scanning probe microscope (SPM). By placement of the tip of the probe on the surface of a solid sample, it can obtain localized IR spectra of a wide range of samples. A second mode of analysis is also available; a sample can be taken from the selected location using a technique called thermally assisted nanosampling (TAN), then a spectrum can be obtained of the nanosample while the probe is remote from the surface. We report a novel method of local compositional analysis that combines both of these types of measurement; a reagent is attached to the tip using TAN, then the reagent is placed in contact with analyte. IR spectroscopy can then be used to analyze any interaction between the reagent and surface it is placed in contact with. All of these modes of analysis were illustrated using a metal chelating agent. In the surface mode, changes to a solid bead of a chelating resin were measured using standard PT-FT-IR. In the nanosampling mode of analysis, a particle of a chelating polymer was attached to the tip of the probe using TAN and this was placed in contact with a concentrated calcium solution. Strong spectral changes were observed that mirrored those found when exposing the surface bound chelating resin bead to a solution of the same ion. A semiquantitative simulation of the PT spectrum for a chelating resin bead was achieved using a thermal diffusion model derived from photoacoustic spectroscopy indicating that semiquantitative or quantitative measurements will be possible in such a system. PMID:19957959
Montaux-Lambert, Antoine; Mercère, Pascal; Primot, Jérôme
2015-11-01
An interferogram conditioning procedure, for subsequent phase retrieval by Fourier demodulation, is presented here as a fast iterative approach aiming at fulfilling the classical boundary conditions imposed by Fourier transform techniques. Interference fringe patterns with typical edge discontinuities were simulated in order to reveal the edge artifacts that classically appear in traditional Fourier analysis, and were consecutively used to demonstrate the correction efficiency of the proposed conditioning technique. Optimization of the algorithm parameters is also presented and discussed. Finally, the procedure was applied to grating-based interferometric measurements performed in the hard X-ray regime. The proposed algorithm enables nearly edge-artifact-free retrieval of the phase derivatives. A similar enhancement of the retrieved absorption and fringe visibility images is also achieved. PMID:26561119
Computational chemistry, in conjunction with gas chromatography/mass spectrometry/Fourier transform infrared spectrometry (GC/MS/FT-IR), was used to tentatively identify seven tetrachlorobutadiene (TCBD) isomers detected in an environmental sample. Computation of the TCBD infrare...
NASA Astrophysics Data System (ADS)
Sivkov, A. V.; Mudraya, I. S.; Revenko, S. V.; Ibragimov, A. R.; Nesterov, A. V.; Gavrilov, I. Yu; Kirpatovsky, V. I.; Stranadko, M. V.
2010-04-01
Original hardware and software system was used to record and analyze the variations of electrical impedance of the urinary bladder in narcotized rats (n=7) at rest, during instillation of physiological saline into the bladder resulted in elevation of intravesical pressure, and during subsequent urination accompanied by intravesical pressure release. Fourier analysis of impedance variations revealed three periodic components with the frequencies of heartbeat, respiration, and the Mayer wave (~0.1 Hz). In resting bladder, the amplitude of Mayer and respiratory spectrum peaks were high, and they increased to a different extent during physiological elevation of intravesical pressure, while a small cardiac peak did not changed significantly and tended to decrease at high intravesical pressure. Urination released intravesical pressure and restored all the peaks to the resting level. It is hypothesized that Mayer and respiratory bioimpedance oscillations of urinary bladder are neural in origin, while the cardiac peak is mainly determined by hydrodynamic arterial pulsations. The novel method can assess vesical circulation and its neural control at various phases of bladder activity.
Dishberger, Debra McLean
1983-04-01
This report represents a continuation of gravity work in the Cascade Mountains of Washington supported by the Division of Geology and Earth Resources since 1974. The purpose of this research has been collection of baseline gravity data for use in geothermal resource evaluation. Results of the Division's gravity studies to date are given in Danes and Phillips (1983a, 1983b). One of the problems encountered when analyzing gravity data is distinguishing between those parts of the data that represent geologic structures of interest, and those that do not. In many cases, the features of interest are relatively small, near-surface features, such as those sought in mineral, petroleum, or geothermal exploration. Gravity anomalies caused by such structures may be distorted or masked by anomalies caused by larger, deeper geologic structures. Gravity anomalies caused by relatively shallow, small geologic structures are termed residual anomalies. Those due to broad, deep-seated features can be described as regional anomalies. The purpose of this report is to describe a Fourier analysis method for separating residual and regional gravity anomalies from a complete Bouguer gravity anomaly field. The technique has been applied to gravity data from the Southern Cascade Mountains, Washington. Residual gravity anomaly maps at a scale of 1:250,000 are presented for various regional wavelength filters, and a power spectrum of the frequency components in the South Cascade gravity data is displayed. No attempt is made to interpret the results of this study in terms of geologic structures.
Spectroscopic analysis of bladder cancer tissues using Fourier transform infrared spectroscopy
NASA Astrophysics Data System (ADS)
Al-Muslet, Nafie A.; Ali, Essam E.
2012-03-01
Bladder cancer is one of the most common cancers in Africa. It takes several days to reach a diagnosis using histological examinations of specimens obtained by endoscope, which increases the medical expense. Recently, spectroscopic analysis of bladder cancer tissues has received considerable attention as a diagnosis technique due to its sensitivity to biochemical variations in the samples. This study investigated the use of Fourier transform infrared (FTIR) spectroscopy to analyze a number of bladder cancer tissues. Twenty-two samples were collected from 11 patients diagnosed with bladder cancer from different hospitals without any pretreatment. From each patient two samples were collected, one normal and another cancerous. FTIR spectrometer was used to differentiate between normal and cancerous bladder tissues via changes in spectra of these samples. The investigations detected obvious changes in the bands of proteins (1650, 1550 cm-1), lipids (2925, 2850 cm-1), and nucleic acid (1080, 1236 cm-1). The results show that FTIR spectroscopy is promising as a rapid, accurate, nondestructive, and easy to use alternative method for identification and diagnosis of bladder cancer tissues.
Portable Fourier Transform Spectroscopy for Analysis of Surface Contamination and Quality Control
NASA Technical Reports Server (NTRS)
Pugel, Diane
2012-01-01
Progress has been made into adapting and enhancing a commercially available infrared spectrometer for the development of a handheld device for in-field measurements of the chemical composition of various samples of materials. The intent is to duplicate the functionality of a benchtop Fourier transform infrared spectrometer (FTIR) within the compactness of a handheld instrument with significantly improved spectral responsivity. Existing commercial technology, like the deuterated L-alanine triglycine sulfide detectors (DLATGS), is capable of sensitive in-field chemical analysis. This proposed approach compares several subsystem elements of the FTIR inside of the commercial, non-benchtop system to the commercial benchtop systems. These subsystem elements are the detector, the preamplifier and associated electronics of the detector, the interferometer, associated readout parameters, and cooling. This effort will examine these different detector subsystem elements to look for limitations in each. These limitations will be explored collaboratively with the commercial provider, and will be prioritized to meet the deliverable objectives. The tool design will be that of a handheld gun containing the IR filament source and associated optics. It will operate in a point-and-shoot manner, pointing the source and optics at the sample under test and capturing the reflected response of the material in the same handheld gun. Data will be captured via the gun and ported to a laptop.
Cleary, Sean P; Thompson, Avery M; Prell, James S
2016-06-21
Highly heterogeneous samples that are difficult to resolve chromatographically arise in many contexts, including hetero-oligomeric protein assemblies, chaperone-target and protein-lipid assemblies, and long-chain polymers. Native mass spectrometry has emerged as a powerful tool to probe the stoichiometry and structure of biomolecular ion complexes, including megadalton-sized assemblies and assemblies with dozens of subunits. However, mass spectra of these ions are often highly congested, obfuscating determination of charge state, total mass, or subunit mass with conventional analysis methods. Here, we present a fast Fourier transform-based algorithm that can be used to deconvolve highly congested mass spectra for heterogeneous ion populations with repeated subunits. The method is parameter-free and requires no initial guesses of charge states, total mass, or subunit mass. To demonstrate a range of applications, the method is applied to ubiquitin with multiple adductions of sodium and potassium, single and mixed polymers, and self-assembled native protein-lipid complexes (Nanodiscs). The algorithm facilitates identification of the charge states, subunit mass, and charge-state specific total mass distribution present in the ion population. Results from application of the algorithm to these analytes include the first reported mass spectra and lipid stoichiometries of intact Nanodiscs containing lipid-raft associated sphingomyelin. Advantages to using this method with ion assemblies that have undergone minimal gas-phase collisional "clean-up" to retain native-like stoichiometries are discussed. PMID:27213759
NASA Astrophysics Data System (ADS)
Vipindas, V.; Gopinath, Sumesh; Girish, T. E.
2016-04-01
Galactic cosmic rays (GCRs) that traverse the heliosphere, in the energy range from several 100 MeV to a few GeV, are subjected to heliospheric modulation. GCRs interact with varying fields of the heliosphere to produce fluctuations in cosmic-ray intensity with variations in solar activity. The effects of modulation are continuously measured by the well-established world-wide neutron monitor network. Solar activity indices and cosmic-ray neutron monitor rates (at different cut-off rigidities) have been used to compare Fourier, Hilbert, and higher-order spectral (bispectral) features of GCR intensity variations at six stations for a period of nearly 50 years. The present study reveals that GCRs exhibit a number of short- and long-term periodicities that vary between 9 days and 22 years. The bispectral analysis shows the characteristic features of nonlinear coupling and complex phase relationships between various harmonics present in GCRs and solar activity proxies. We also offer possible explanations for the observed periodicities with the help of the previous findings.
Fourier-transform method of data compression and temporal fringe pattern analysis
Tuck Wah Ng; Kar Tien Ang
2005-11-20
Temporal fringe pattern analysis is invaluable in studies of transient phenomena but necessitates large data storage for two essential sets of data, i.e., fringe pattern intensity and deformation phase. We describe a compression scheme based on the Fourier-transform method for temporal fringe data storage that permits retrieval of both the intensity and the deformation phase. When the scheme was used with simulated temporal wavefront interferometry intensity fringe patterns, a high compression ratio of 10.77 was achieved, with a significant useful data ratio of 0.859. The average root-mean-square error in phase value restored was a low 0.0015 rad. With simulated temporal speckle interferometry intensity fringe patterns, the important paremeters varied with the modulation cutoff value applied. For a zero modulation cutoff value, the ratio of data points and the compression ratio values obtained were roughly the same as in wavelength interferometry, albeit the average root-mean-square error in the phase value restored was far higher. By increasing the modulation cutoff value we attained significant reduction and increase in the ratio of data points and the compression ratio, respectively, whereas the average root-mean-square error in the restored phase values was reduced only slightly.
Analysis of pork adulteration in beef meatball using Fourier transform infrared (FTIR) spectroscopy.
Rohman, A; Sismindari; Erwanto, Y; Che Man, Yaakob B
2011-05-01
Meatball is one of the favorite foods in Indonesia. The adulteration of pork in beef meatball is frequently occurring. This study was aimed to develop a fast and non destructive technique for the detection and quantification of pork in beef meatball using Fourier transform infrared (FTIR) spectroscopy and partial least square (PLS) calibration. The spectral bands associated with pork fat (PF), beef fat (BF), and their mixtures in meatball formulation were scanned, interpreted, and identified by relating them to those spectroscopically representative to pure PF and BF. For quantitative analysis, PLS regression was used to develop a calibration model at the selected fingerprint regions of 1200-1000 cm(-1). The equation obtained for the relationship between actual PF value and FTIR predicted values in PLS calibration model was y = 0.999x + 0.004, with coefficient of determination (R(2)) and root mean square error of calibration are 0.999 and 0.442, respectively. The PLS calibration model was subsequently used for the prediction of independent samples using laboratory made meatball samples containing the mixtures of BF and PF. Using 4 principal components, root mean square error of prediction is 0.742. The results showed that FTIR spectroscopy can be used for the detection and quantification of pork in beef meatball formulation for Halal verification purposes. PMID:21227596
Fast Fourier transformation analysis of kindling-induced afterdischarge in the rabbit hippocampus.
Tsuchiya, Komei; Kogure, Shinichi
2011-06-01
Kindling is a widely used animal model of intractable temporal lobe epilepsy. In the present study, we performed fast Fourier transformation (FFT) analysis of kindling-induced afterdischarge (AD) in the rabbit hippocampus. Ten adult rabbits were used. Kindling stimulation to the right hippocampus was delivered as a train of biphasic pulses (1 ms duration each) of 50 Hz for 1s, with suprathreshold intensity for AD. Motor responses were classified into five stages according to the conventional criteria. Of 10 animals, five developed stage 5 convulsions with a mean of 21 stimulations (kindled (K) group), while the remaining five animals did not (incomplete kindling (IK) group). We standardized each ratio of power spectral density of lower frequency band component (LFB: 0-9 Hz) and the higher frequency band (HFB: 12-30 Hz) in the initial stage as 1.0. The IK group exhibited small decrements (0.99 and 0.94 times) in LFB and HFB components at the final stage. In contrast, the K group exhibited a significantly (p<0.05) large decrement (0.49 times) in the LFB component and a very large increment (4.45 times) of HFB component at the final stage. Correlation analyses were performed between alteration of power spectral density ratio of the HFB component and AD duration, interictal discharge frequency, and behavioral stage during kindling progression. Fairly strong positive correlations were found in all cases in the K group. FFT analysis of kindling-induced AD demonstrated an important role of the HFB component: enhancement of the HFB component is associated with kindled stage, while decrement of it is associated with incomplete kindling stage. These findings suggest that FFT analysis of stimulus-induced and spontaneous seizure discharges is useful for examination of the progression of epileptic disorders. PMID:21498048
Finn, J.E.; Burger, C.V.; Holland-Bartels, L.
1997-01-01
We used otolith banding patterns formed during incubation to discriminate among hatchery- and wild-incubated fry of sockeye salmon Oncorhynchus nerka from Tustumena Lake, Alaska. Fourier analysis of otolith luminance profiles was used to describe banding patterns: the amplitudes of individual Fourier harmonics were discriminant variables. Correct classification of otoliths to either hatchery or wild origin was 83.1% (cross-validation) and 72.7% (test data) with the use of quadratic discriminant function analysts on 10 Fourier amplitudes. Overall classification rates among the six test groups (one hatchery and five wild groups) were 46.5% (cross-validation) and 39.3% (test data) with the use of linear discriminant function analysis on 16 Fourier amplitudes. Although classification rates for wild-incubated fry from any one site never exceeded 67% (cross-validation) or 60% (test data), location-specific information was evident for all groups because the probability of classifying an individual to its true incubation location was significantly greater than chance. Results indicate phenotypic differences in otolith microstructure among incubation sites separated by less than 10 km. Analysis of otolith luminance profiles is a potentially useful technique for discriminating among and between various populations of hatchery and wild fish.
Fourier Analysis and Structure Determination--Part III: X-ray Crystal Structure Analysis.
ERIC Educational Resources Information Center
Chesick, John P.
1989-01-01
Discussed is single crystal X-ray crystal structure analysis. A common link between the NMR imaging and the traditional X-ray crystal structure analysis is reported. Claims that comparisons aid in the understanding of both techniques. (MVL)
Resolution issues in the analysis of radar signals via Fourier approaches
NASA Astrophysics Data System (ADS)
Flores, Benjamin C.; Ochoa, Hector A.; Thomas, Gabriel
2004-08-01
Classical work in the field of high-resolution radar often assumes that an echo signal is made of a number of components that can be decomposed via Fourier analysis. Adjacent components are said to be resolved in the frequency domain if the intensity between them drops at least 3 decibels. This working definition is an extension of Lord Rayleigh's criterion for optical resolution. The problem with this approach is that whereas Rayleigh's criterion assumes signal incoherence, thus allowing for the addition of power components, a high-resolution radar signal is often the coherent sum of sinusoids, which implies voltage addition. The purpose of this paper is to discuss the consequences of using Rayleigh's criterion in the analysis of radar signals. Specifically, computer simulations using a complex signal are analyzed via the periodogram as the relative phase between the two components of the signal is allowed to change. The net effect introduced by this phase variation is to reduce or increase the spacing and intensity between two adjacent spectral peaks. These changes are due to constructive or destructive interference of spectral cross terms that cannot be ignored when attempting to resolve frequency components from one another. For instance, the simulations show that when using the averaged periodogram, the intensity in-between two adjacent components is above the -3 decibel threshold for a phase range of 1.2π radians, although the standard resolution criterion of c/2β is satisfied. Similar results are obtained when using a number of windows that are known to control sidelobe levels. Thus, the use of Rayleigh's criterion to define the resolution of a high-resolution radar system is technically inconsistent and undermines our ability to perform quantitative comparisons of target profiles, Doppler profiles and range-Doppler images. In this light, the authors promote the adoption of alternative criteria for judging resolution gains based on the norm of the signal
NASA Astrophysics Data System (ADS)
Harris, Brent; Steber, Amanda; Pate, Brooks
2014-06-01
A chirped-pulse Fourier transform mm-wave spectrometer has been tested in analytical chemistry applications of headspace analysis of volatile species. A solid-state mm-wave light source (260-290 GHz) provides 30-50 mW of power. This power is sufficient to achieve optimal excitation of individual transitions of molecules with dipole moments larger than about 0.1 D. The chirped-pulse spectrometer has near 100% measurement duty cycle using a high-speed digitizer (4 GS/s) with signal accumulation in an FPGA. The combination of the ability to perform optimal pulse excitation and near 100% measurement duty cycle gives a spectrometer that is fully optimized for trace detection. The performance of the instrument is tested using an EPA sample (EPA VOC Mix 6 - Supelco) that contains a set of molecules that are fast eluting on gas chromatographs and, as a result, present analysis challenges to mass spectrometry. The ability to directly analyze the VOC mixture is tested by acquiring the full bandwidth (260-290 GHz) spectrum in a "high dynamic range" measurement mode that minimizes spurious spectrometer responses. The high-resolution of molecular rotational spectroscopy makes it easy to analyze this mixture without the need for chemical separation. The sensitivity of the instrument for individual molecule detection, where a single transition is polarized by the excitation pulse, is also tested. Detection limits in water will be reported. In the case of chloromethane, the detection limit (0.1 microgram/L), matches the sensitivity reported in the EPA measurement protocol (EPA Method 524) for GC/MS.
NASA Astrophysics Data System (ADS)
Ota, T. A.
2013-10-01
Photonic Doppler velocimetry, also known as heterodyne velocimetry, is a widely used optical technique that requires the analysis of frequency modulated signals. This paper describes an investigation into the errors of short time Fourier transform analysis. The number of variables requiring investigation was reduced by means of an equivalence principle. Error predictions, as the number of cycles, samples per cycle, noise level, and window type were varied, are presented. The results were found to be in good agreement with analytical models.
Ota, T. A.
2013-10-15
Photonic Doppler velocimetry, also known as heterodyne velocimetry, is a widely used optical technique that requires the analysis of frequency modulated signals. This paper describes an investigation into the errors of short time Fourier transform analysis. The number of variables requiring investigation was reduced by means of an equivalence principle. Error predictions, as the number of cycles, samples per cycle, noise level, and window type were varied, are presented. The results were found to be in good agreement with analytical models.
Multiband analysis and synthesis of spectro-temporal modulations of Fourier spectrogram.
Chi, Tai-Shih; Hsu, Chung-Chien
2011-05-01
The two-dimensional spectro-temporal modulation filtering concept of the auditory model [T. Chi, P. Ru, and S. A. Shamma, J. Acoust. Soc. Am. 118(2), 887-906 (2005)] is implemented on the Fourier spectrogram. The Fourier magnitude spectrogram is analyzed in terms of its joint spectro-temporal modulations, which embed the temporal dynamics and spectral structures. Instead of iterative projection methods, the overlap-and-add method is adopted to invert modified Fourier spectrograms back to sounds. The proposed framework not only provides a similar spectro-temporal analytical process for sounds as the auditory model but also produces synthesized sounds with better quality in a timely manner, which makes proposed framework feasible to human speech recognition (HSR) applications as well. PMID:21568374
Wang, Ya-Mei; Ma, Shu-Ling; Feng, Li-Qun
2014-03-01
Wood preservative treatment can improve defects of plantation wood such as easy to corrupt and moth eaten. Among them heat-treatment is not only environmental and no pollution, also can improve the corrosion resistance and dimension stability of wood. In this test Poplar and Mongolian Seoteh Pine was treated by soybean oil as heat-conducting medium, and the heat treatment wood was studied for indoor decay resistance; wood chemical components before and after treatment, the effect of heat treatment on wood decay resistance performance and main mechanism of action were analysed by Fourier infrared spectrometric. Results showed that the mass loss rate of poplar fell from 19.37% to 5% and Mongolian Seoteh Pine's fell from 8.23% to 3.15%, so oil heat treatment can effectively improve the decay resistance. Infrared spectrum analysis shows that the heat treatment made wood's hydrophilic groups such as hydroxyl groups in largely reduced, absorbing capacity decreased and the moisture of wood rotting fungi necessary was reduced; during the heat treatment wood chemical components such as cellulose, hemicellu lose were degraded, and the nutrient source of wood rotting fungi growth necessary was reduced. Wood decay fungi can grow in the wood to discredit wood is because of that wood can provide better living conditions for wood decay fungi, such as nutrients, water, oxygen, and so on. The cellulose and hemicellulose in wood is the main nutrition source of wood decay fungi. So the oil heat-treatment can reduce the cellulose, hemicellulose nutrition source of wood decay fungi so as to improve the decay resistance of wood. PMID:25208386
Fourier transform infrared spectroscopic analysis of sperm chromatin structure and DNA stability.
Oldenhof, H; Schütze, S; Wolkers, W F; Sieme, H
2016-05-01
Sperm chromatin structure and condensation determine accessibility for damage, and hence success of fertilization and development. The aim of this study was to reveal characteristic spectral features coinciding with abnormal sperm chromatin packing (i.e., DNA-protein interactions) and decreased fertility, using Fourier transform infrared spectroscopy. Chromatin structure in spermatozoa obtained from different stallions was investigated. Furthermore, spermatozoa were exposed to oxidative stress, or treated with thiol-oxidizing and disulfide-reducing agents, to alter chromatin structure and packing. Spectroscopic studies were corroborated with flow cytometric analyses using the DNA-intercalating fluorescent dye acridine orange. Decreased fertility of individuals correlated with increased abnormal sperm morphology and decreased stability toward induced DNA damage. Treatment with the disulfide reducing agent dithiothreitol resulted in increased sperm chromatin decondensation and DNA accessibility, similar as found for less mature epididymal spermatozoa. In situ infrared spectroscopic analysis revealed that characteristic bands arising from the DNA backbone (ν1230, ν1086, ν1051 cm(-1) ) changed in response to induced oxidative damage, water removal, and decondensation. This coincided with changes in the amide-I region (intensity at ν1620 vs. ν1640 cm(-1) ) denoting concomitant changes in protein secondary structure. Reduction in protein disulfide bonds resulted in a decreased value of the asymmetric to symmetric phosphate band intensity (ν1230/ν1086 cm(-1) ), suggesting that this band ratio is sensitive for the degree of chromatin condensation. Moreover, when analyzing spermatozoa from different individuals, it was found that the asymmetric/symmetric phosphate band ratio negatively correlated with the percentage of morphologically abnormal spermatozoa. PMID:26916383
NASA Astrophysics Data System (ADS)
Townley-Smith, Keeley; Nave, Gillian; Imperial College London
2016-01-01
There is an on-going project in the Atomic Spectroscopy Group at NIST to obtain comprehensive spectral data for all of the singly ionized iron group elements and acquire more accurate energy levels, wavelengths and hyperfine structure (HFS) constants. The heavy abundance of the iron group elements and their contributions to a wide range of stellar spectra makes them of interest for astrophysical observations.Existing spectroscopic data for Mn are insufficient to model spectra obtained from HgMn stars such as HD 175640. Since manganese has an odd number of nucleons, its spectral lines generally exhibit HFS, a relativistic effect due to interaction between the magnetic moment of the nucleus and the orbiting electrons. If proper treatment of line broadening effects such as HFS is not taken, there is a poor fit of the lines in stellar spectra, leading to an overestimate of the abundance of Mn. The abnormally high abundance of manganese in HgMn stars means both weak and strong transitions are important. Weak lines may not be observed in the laboratory, but HFS constants for them can be derived from stronger transitions that combine with the two levels involved in the weak transition.Holt et al. (1999) measured HFS constants for 56 energy levels using laser spectroscopy. We have analyzed Fourier Transform spectra of a high current Mn/Ni hollow cathode lamp to obtain magnetic dipole A constants levels of Mn II. The A constants of Holt et al. (1999, MNRAS 306, 1007) for the z5P, z7P2, a5P and z5F levels were the starting point for our analysis, from which we derived A constants for 71 energy levels, including 51 previously unstudied levels. Our A constant for the a7S3 ground level differs by 5x10-4 cm-1 from that of Blackwell-Whitehead et al. (2005, ApJS 157, 402) and has a factor of 6 lower uncertainty.
Analysis of aircraft exhausts with Fourier-transform infrared emission spectroscopy.
Heland, J; Schäfer, K
1997-07-20
Because of the worldwide growth in air traffic and its increasing effects on the atmospheric environment, it is necessary to quantify the direct aircraft emissions at all altitudes. In this study Fourier-transform infrared emission spectroscopy as a remote-sensing multi-component-analyzing technique for aircraft exhausts was investigated at ground level with a double pendulum interferometer and a line-by-line computer algorithm that was applied to a multilayer radiative transfer problem. Initial measurements were made to specify the spectral windows for traceable compounds, to test the sensitivity of the system, and to develop calibration and continuum handling procedures. To obtain information about the radial temperature and concentration profiles, we developed an algorithm for the analysis of an axial-symmetric multilayered plume by use of the CO(2) hot band at approximately 2400 cm(-1). Measurements were made with several in-service engines. Effects that were due to engine aging were detected but have to be analyzed systematically in the near future. Validation measurements were carried out with a conventional propane gas burner to compare the results with those obtained with standard measurement equipment. These measurements showed good agreement to within +/-20% for the CO and NO(x) results. The overall accuracy of the system was found to be +/-30%. The detection limits of the system for a typical engine plume (380 degrees C, ? = 50 cm) are below 0.1% for CO(2), ~0.7% for H(2)O, ~20 ppmv (parts per million by volume) for CO, and ~90 ppmv for NO. PMID:18259296
Shawkey, Matthew D.; Saranathan, Vinodkumar; Pálsdóttir, Hildur; Crum, John; Ellisman, Mark H.; Auer, Manfred; Prum, Richard O.
2009-01-01
Organismal colour can be created by selective absorption of light by pigments or light scattering by photonic nanostructures. Photonic nanostructures may vary in refractive index over one, two or three dimensions and may be periodic over large spatial scales or amorphous with short-range order. Theoretical optical analysis of three-dimensional amorphous nanostructures has been challenging because these structures are difficult to describe accurately from conventional two-dimensional electron microscopy alone. Intermediate voltage electron microscopy (IVEM) with tomographic reconstruction adds three-dimensional data by using a high-power electron beam to penetrate and image sections of material sufficiently thick to contain a significant portion of the structure. Here, we use IVEM tomography to characterize a non-iridescent, three-dimensional biophotonic nanostructure: the spongy medullary layer from eastern bluebird Sialia sialis feather barbs. Tomography and three-dimensional Fourier analysis reveal that it is an amorphous, interconnected bicontinuous matrix that is appropriately ordered at local spatial scales in all three dimensions to coherently scatter light. The predicted reflectance spectra from the three-dimensional Fourier analysis are more precise than those predicted by previous two-dimensional Fourier analysis of transmission electron microscopy sections. These results highlight the usefulness, and obstacles, of tomography in the description and analysis of three-dimensional photonic structures. PMID:19158016
de Sá, M E; Ferreira, R; Rebelo, J R; Nogueira, A; Baptista, A M; Ribeiro, C
2001-05-01
III 17.9%; p < .0001). LV ejection fraction was statistically different in the four groups considered (I = 30.0% +/- 3.7; II = 39.9% +/- 2.9; III = 49.0% +/- 2.5; IV = 62.0% +/- 3.2). The degree of phase delay in aneurysmatic zones was quantified by the phase histogram. Average value of phase for the left ventricle was 129.7 +/- 8.4 degrees, and for the aneurysm it was 238.0 +/- 5.0 with an average phase delay of 104.8 +/- 4.1 degrees. The association of phase and amplitude images and the measurements of phase and amplitude values on the histograms allowed the distinction of akinetic aneurysm (phase delay and low amplitude) from the dyskinetic aneurysms (phase delay and high amplitude). Half of the isotopic diagnosis of aneurysms have been confirmed by classic contrast angiography, and a third of then have undergone surgery. The two dyskinetic aneurysms that have been submitted to aneurysmectomy had pos-operative improvement of LV function. On summary, phase and amplitude analysis by the Fourier method, which is independent of LV geometry, showed that LV regions with high phase values are associated with severe regional wall motion abnormalities and low ejections fractions. The definition of the sequence and amplitude of ventricular contraction allows the distinction of akinetic and dyskinetic aneurysms, anticipating the method as a valid contribution for the screening of patients likely to benefit from aneurysmectomy. PMID:11515305
NASA Astrophysics Data System (ADS)
Acworth, R. I.; Rau, Gabriel C.; McCallum, Andrew M.; Andersen, Martin S.; Cuthbert, Mark O.
2015-02-01
The long-term monitoring records of hydraulic heads frequently contain fluctuations originating from different cyclic drivers. Fourier analysis applied to these records can reveal connected surface-water/groundwater system characteristics. The various components of the atmospheric tides, the earth tides and the presence of diurnal responses to evapotranspiration are identified and isolated through band-pass filtering of data recorded from both vented and absolute gauge transducers. The signature of the different cyclic drivers is contained in amplitude and phase of the various signal components and can be used to determine the degree of system confinement. A methodology is described for the calculation of barometric efficiency in confined aquifers based upon the amplitude of the M2 and S2 components of the earth and atmospheric tides. It is demonstrated that Fourier analysis of water-level fluctuations is a simple but underused tool that can help to characterise shallow groundwater systems.
Fourier-Transform Infrared Spectroscopy Analysis of Modified Cotton Trash Extracts
Technology Transfer Automated Retrieval System (TEKTRAN)
In a previous study, Fourier transform infrared spectroscopy (FTIR) was utilized in identifying different types of botanical cotton trash as each was subjected to simulations of ginning and textile processing. Changes in the infrared spectra that occurred after heat treatment indicated that the nee...
Franck-Condon Factors for Diatomics: Insights and Analysis Using the Fourier Grid Hamiltonian Method
ERIC Educational Resources Information Center
Ghosh, Supriya; Dixit, Mayank Kumar; Bhattacharyya, S. P.; Tembe, B. L.
2013-01-01
Franck-Condon factors (FCFs) play a crucial role in determining the intensities of the vibrational bands in electronic transitions. In this article, a relatively simple method to calculate the FCFs is illustrated. An algorithm for the Fourier Grid Hamiltonian (FGH) method for computing the vibrational wave functions and the corresponding energy…
Technology Transfer Automated Retrieval System (TEKTRAN)
A new chemometric method based on absorbance ratios from Fourier transform infrared spectra was devised to analyze multicomponent biodegradable plastics. The method uses the BeerLambert law to directly compute individual component concentrations and weight losses before and after biodegradation of c...
Fourier Descriptor Analysis and Unification of Voice Range Profile Contours: Method and Applications
ERIC Educational Resources Information Center
Pabon, Peter; Ternstrom, Sten; Lamarche, Anick
2011-01-01
Purpose: To describe a method for unified description, statistical modeling, and comparison of voice range profile (VRP) contours, even from diverse sources. Method: A morphologic modeling technique, which is based on Fourier descriptors (FDs), is applied to the VRP contour. The technique, which essentially involves resampling of the curve of the…
NASA Astrophysics Data System (ADS)
Dai, Xianglu; Xie, Huimin; Wang, Huaixi; Li, Chuanwei; Liu, Zhanwei; Wu, Lifu
2014-02-01
The geometric phase analysis (GPA) method based on the local high resolution discrete Fourier transform (LHR-DFT) for deformation measurement, defined as LHR-DFT GPA, is proposed to improve the measurement accuracy. In the general GPA method, the fundamental frequency of the image plays a crucial role. However, the fast Fourier transform, which is generally employed in the general GPA method, could make it difficult to locate the fundamental frequency accurately when the fundamental frequency is not located at an integer pixel position in the Fourier spectrum. This study focuses on this issue and presents a LHR-DFT algorithm that can locate the fundamental frequency with sub-pixel precision in a specific frequency region for the GPA method. An error analysis is offered and simulation is conducted to verify the effectiveness of the proposed method; both results show that the LHR-DFT algorithm can accurately locate the fundamental frequency and improve the measurement accuracy of the GPA method. Furthermore, typical tensile and bending tests are carried out and the experimental results verify the effectiveness of the proposed method.
Fourier Transform Mass Spectrometry
Scigelova, Michaela; Hornshaw, Martin; Giannakopulos, Anastassios; Makarov, Alexander
2011-01-01
This article provides an introduction to Fourier transform-based mass spectrometry. The key performance characteristics of Fourier transform-based mass spectrometry, mass accuracy and resolution, are presented in the view of how they impact the interpretation of measurements in proteomic applications. The theory and principles of operation of two types of mass analyzer, Fourier transform ion cyclotron resonance and Orbitrap, are described. Major benefits as well as limitations of Fourier transform-based mass spectrometry technology are discussed in the context of practical sample analysis, and illustrated with examples included as figures in this text and in the accompanying slide set. Comparisons highlighting the performance differences between the two mass analyzers are made where deemed useful in assisting the user with choosing the most appropriate technology for an application. Recent developments of these high-performing mass spectrometers are mentioned to provide a future outlook. PMID:21742802
Sperling, Edit; Bunner, Anne E.; Sykes, Michael T.; Williamson, James R.
2008-01-01
Quantitative proteomic mass spectrometry involves comparison of the amplitudes of peaks resulting from different isotope labeling patterns, including fractional atomic labeling and fractional residue labeling. We have developed a general and flexible analytical treatment of the complex isotope distributions that arise in these experiments, using Fourier transform convolution to calculate labeled isotope distributions and least-squares for quantitative comparison with experimental peaks. The degree of fractional atomic and fractional residue labeling can be determined from experimental peaks at the same time as the integrated intensity of all of the isotopomers in the isotope distribution. The approach is illustrated using data with fractional 15N-labeling and fractional 13C-isoleucine labeling. The least-squares Fourier transform convolution approach can be applied to many types of quantitive proteomic data, including data from stable isotope labeling by amino acids in cell culture and pulse labeling experiments. PMID:18522437
Field-of-view analysis of a polarization interference Fourier transform imaging spectrometer.
DeHoog, Edward; Xia, Xiaowei; Parfenov, Alexander; Shih, Min-Yi
2011-09-20
The Fourier transform imaging spectrometer (FTIS) is an important tool for the measurement of spectral information in a scene. Advances in electro-optic crystal systems have led to the advent of the FTIS based on polarization interference filters. The operation of these devices as spectrometers has been well characterized, but the imaging capabilities have yet to be thoroughly explored. We explore the field-of-view limitations that occur when using this particular type of FTIS. PMID:21947057
Discrete fourier transform (DFT) analysis for applications using iterative transform methods
NASA Technical Reports Server (NTRS)
Dean, Bruce H. (Inventor)
2012-01-01
According to various embodiments, a method is provided for determining aberration data for an optical system. The method comprises collecting a data signal, and generating a pre-transformation algorithm. The data is pre-transformed by multiplying the data with the pre-transformation algorithm. A discrete Fourier transform of the pre-transformed data is performed in an iterative loop. The method further comprises back-transforming the data to generate aberration data.
FFTFIL; a filtering program based on two-dimensional Fourier analysis of geophysical data
Hildenbrand, T.G.
1983-01-01
The filtering program 'fftfil' performs a variety of operations commonly required in geophysical studies of gravity, magnetic, and terrain data. Filtering operations are carried out in the wave number domain where the Fourier coefficients of the input data are multiplied by the response of the selected filter. Input grids can be large (2=number of rows or columns=1024) and are not required to have numbers of rows and columns equal to powers of two.
Mid-Latitude Temperatures at 87 km: Results From Multi-Instrument Fourier Analysis
NASA Technical Reports Server (NTRS)
Drob, Douglas P.; Picone, J. M.; Eckermann, Stephen D.; She, C . Y.; Kafkalidis, J. F.; Ortland, D. A.; Niciejewski, R. J.; Killeen, T. L.
2000-01-01
Using a novel Fourier fitting method we combine two years of mid-latitude temperature measurements at 87 km from the High Resolution Doppler Imager, the Colorado State University lidar, and the Peach Mountain Interferometer. After accounting for calibration bias, significant local-time variations on the order of 10 K were observed. Stationary planetary waves with amplitudes up to 10 K were observed during winter, with weaker wave amplitudes occurring during other seasons. Because of calibration biases among these instruments, we could estimate the annual mean temperature to no better than 193.5 plus or minus 8.5 K.
Gurka, D F; Titus, R; Robins, K; Wong, A; Wurrey, C J; Durig, J R; Shen, Z; Burkhard, L P
1996-12-01
Computational chemistry, in conjunction with gas chromatography/mass spectrometry/Fourier transform infrared spectrometry (GC/MS/FT-IR), was used to tentatively identify seven tetrachlorobutadiene (TCBD) isomers detected in an environmental sample. Computation of the TCBD infrared spectra was performed with the Gaussian quantum chemistry software. The Hartree-Fock/6-31G* level of theory was employed, with IR frequencies scaled by a standard factor of 0.89. This approach shows great promise as a means of characterizing or confirming environmental analyte identifications when standard spectra, or pure standards required to measure standard spectra, are unavailable. PMID:21619333
NASA Technical Reports Server (NTRS)
Beecken, Brian P.; Kleinman, Randall R.
2004-01-01
New developments in infrared sensor technology have potentially made possible a new space-based system which can measure far-infrared radiation at lower costs (mass, power and expense). The Stationary Imaging Fourier Transform Spectrometer (SIFTS) proposed by NASA Langley Research Center, makes use of new detector array technology. A mathematical model which simulates resolution and spectral range relationships has been developed for analyzing the utility of such a radically new approach to spectroscopy. Calculations with this forward model emulate the effects of a detector array on the ability to retrieve accurate spectral features. Initial computations indicate significant attenuation at high wavenumbers.
Schoonover, J R; Steckle, Jr., W P; Elliot, N; Ebey, P S; Nobile, A; Nikroo, A; Cook, R C; Letts, S A
2005-06-16
Planar samples of varying thicknesses of both CH and CD glow discharge polymer have been measured with Fourier transform infrared (FTIR) spectroscopy before and after exposure to deuterium-tritium (DT) gas at elevated temperature and pressure. Planar samples of polyimide films made from both hydrogenated and deuterated precursors have also been examined by FTIR before and after DT exposure. The post-exposure FTIR spectra demonstrated no measurable exchange of hydrogen with deuterium or tritium for either polymer. Evidence for oxidation of the glow discharge polymer due to atmospheric oxygen was the only chemical change indicated by the FTIR data.
NASA Astrophysics Data System (ADS)
Tavares, Paulo J.; Vaz, Mário A. P.
2013-03-01
Gradient range and spatial resolution in Fourier Transform Profilometry depend on the size of the filter window in reciprocal space. The proposed methods to date for the elimination of the fundamental frequency and enlargement of the filter window are either too computationally complex or depend on the possibility of using two frames, thus disabling the method's ability to cope with dynamic situations and subjecting the results to possible intensity changes between the two frame acquisitions. This article describes a simple method for using a single crossed fringe pattern to accomplish that objective, greatly improving the previously reported technique, whilst retaining its main advantages.
Analysis of fixed point FFT for Fourier domain optical coherence tomography systems.
Ali, Murtaza; Parlapalli, Renuka; Magee, David P; Dasgupta, Udayan
2009-01-01
Optical coherence tomography (OCT) is a new imaging modality gaining popularity in the medical community. Its application includes ophthalmology, gastroenterology, dermatology etc. As the use of OCT increases, the need for portable, low power devices also increases. Digital signal processors (DSP) are well suited to meet the signal processing requirements of such a system. These processors usually operate on fixed precision. This paper analyzes the issues that a system implementer faces implementing signal processing algorithms on fixed point processor. Specifically, we show the effect of different fixed point precisions in the implementation of FFT on the sensitivity of Fourier domain OCT systems. PMID:19965018
Fourier transform C-13 NMR analysis of some free and potassium-ion complexed antibiotics.
NASA Technical Reports Server (NTRS)
Ohnishi, M.; Fedarko, M.-C.; Baldeschwieler, J. D.; Johnson, L. F.
1972-01-01
Fourier transforms of the noise-decoupled, natural abundance C-13 NMR free induction decays of the cyclic antibiotic valinomycin and its potassium-ion complex have been obtained at 25.2 MHz. Comparisons are made with C-13 NMR spectra taken at 22.6 MHz of the cyclic antibiotic nonactin and the synthetic polyether dicyclohexyl-18-crown-6 and their potassium complexes. The results obtained suggest that conformational rearrangements of the molecule as a whole can compete with direct interactions between carbons and the potassium ion in determining C-13 chemical shift differences between the free and complexed species.
Mid-latitude temperatures at 87 km: Results from multi-instrument Fourier analysis
NASA Astrophysics Data System (ADS)
Drob, Douglas P.; Picone, J. Michael; Eckermann, Stephen D.; She, C. Y.; Kafkalidis, J. F.; Ortland, D. A.; Niciejewski, R. J.; Killeen, T. L.
2000-08-01
Using a novel Fourier fitting method we combine two years of mid-latitude temperature measurements at 87 km from the High Resolution Doppler Imager, the Colorado State University lidar, and the Peach Mountain Interferometer. After accounting for calibration bias, significant local-time variations on the order of 10 K were observed. Stationary planetary waves with amplitudes up to 10 K were observed during winter, with weaker wave amplitudes occurring during other seasons. Because of calibration biases among these instruments, we could estimate the annual mean temperature to no better than 193.5±8.5 K.
Characterizing the Nanoscale Layers of Tomorrow___s Electronics An Application of Fourier Analysis
Payne, Christopher Bishop; /Princeton U. /SLAC
2012-08-24
Thin film applications are of great interest to the semiconductor industry due to the important role they play in cutting edge technology such as thin film solar cells. X-Ray Reflectivity (XRR) characterizes thin films in a non-destructive and efficient manner yet complications exist in extracting these characteristics from raw XRR data. This study developed and tested two different algorithms to extract quantity of layers and thickness information on the nanometer scale from XRR data. It was concluded that an algorithm involving a local averaging technique revealed this information clearly in Fourier space.
Leszczyński, Adam; Wasilewski, Wojciech
2016-04-01
We present a method to calibrate wavefront distortion of the spatial light modulator setup by registering far-field images of several Gaussian beams diffracted off the modulator. The Fourier transform of resulting interference images reveals phase differences among typically five movable points on the modulator. Repeating this measurement yields a wavefront surface. Next, the amplitude efficiency is calibrated for registering the near-field image. For verification, we produced a superposition of seventh and eighth Bessel beams with different phase velocities and observed their interference. PMID:27140780
Fourier analysis of Solar atmospheric numerical simulations accelerated with GPUs (CUDA).
NASA Astrophysics Data System (ADS)
Marur, A.
2015-12-01
Solar dynamics from the convection zone creates a variety of waves that may propagate through the solar atmosphere. These waves are important in facilitating the energy transfer between the sun's surface and the corona as well as propagating energy throughout the solar system. How and where these waves are dissipated remains an open question. Advanced 3D numerical simulations have furthered our understanding of the processes involved. Fourier transforms to understand the nature of the waves by finding the frequency and wavelength of these waves through the simulated atmosphere, as well as the nature of their propagation and where they get dissipated. In order to analyze the different waves produced by the aforementioned simulations and models, Fast Fourier Transform algorithms will be applied. Since the processing of the multitude of different layers of the simulations (of the order of several 100^3 grid points) would be time intensive and inefficient on a CPU, CUDA, a computing architecture that harnesses the power of the GPU, will be used to accelerate the calculations.
Bangalore, Arjun S.; Demirgian, Jack C.; Boparai, Amrit S.; Small, Gary W.
1999-11-01
The Fourier transform infrared (FT-IR) spectral data of two nerve agent simulants, diisopropyl methyl phosphonate (DIMP) and dimethyl methyl phosphonate (DMMP), are used as test cases to determine the spectral resolution that gives optimal pattern recognition performance. DIMP is used as the target analyte for detection, while DMMP is used to test the ability of the automated pattern recognition methodology to detect the analyte selectively. Interferogram data are collected by using a Midac passive FT-IR instrument. The methodology is based on the application of pattern recognition techniques to short segments of single-beam spectra obtained by Fourier processing the collected interferogram data. The work described in this article evaluates the effect of varying spectral resolution on the pattern recognition results. The objective is to determine the optimal spectral resolution to be used for data collection. The results of this study indicate that the data with a nominal spectral resolution of 16 cm{sup -1} provide sufficient selectivity to give pattern recognition results comparable to that obtained by using higher resolution data. We found that, while higher resolution does not increase selectivity sufficiently to provide better pattern recognition results, lower resolution decreases selectivity and degrades the pattern recognition results. These results can be used as guidelines to maximize detection sensitivity, to minimize the time needed for data collection, and to reduce data storage requirements. (c) 2000 Society for Applied Spectroscopy.
A fractional Fourier transform analysis of the scattering of ultrasonic waves
Tant, Katherine M.M.; Mulholland, Anthony J.; Langer, Matthias; Gachagan, Anthony
2015-01-01
Many safety critical structures, such as those found in nuclear plants, oil pipelines and in the aerospace industry, rely on key components that are constructed from heterogeneous materials. Ultrasonic non-destructive testing (NDT) uses high-frequency mechanical waves to inspect these parts, ensuring they operate reliably without compromising their integrity. It is possible to employ mathematical models to develop a deeper understanding of the acquired ultrasonic data and enhance defect imaging algorithms. In this paper, a model for the scattering of ultrasonic waves by a crack is derived in the time–frequency domain. The fractional Fourier transform (FrFT) is applied to an inhomogeneous wave equation where the forcing function is prescribed as a linear chirp, modulated by a Gaussian envelope. The homogeneous solution is found via the Born approximation which encapsulates information regarding the flaw geometry. The inhomogeneous solution is obtained via the inverse Fourier transform of a Gaussian-windowed linear chirp excitation. It is observed that, although the scattering profile of the flaw does not change, it is amplified. Thus, the theory demonstrates the enhanced signal-to-noise ratio permitted by the use of coded excitation, as well as establishing a time–frequency domain framework to assist in flaw identification and classification. PMID:25792967
Zhou, Mi; Ke, Jian; Li, Bao-li; Tang, Cui-e; Tan, Jun; Liu, Rui; Wang, Hong; Li, Tao; Zhou, Sheng-yin
2015-10-01
This study was performed to establish a method that can quickly and accurately identify adulterated syrup in the pure pineapple juice. A attenuated total internal refraction-fourier transform infrared spectroscopy was used to collect the range of 900 -1 500 cm(-1) infrared spectra of 234 samples pure pineapple juice and adulterated syrup by beet syrup, rice syrup and cassava syrup. By using linear discriminant analysis and support vector machine for the identification model, comparing the full spectral and selected wavelengths based on principal component analysis loading plots of the two models to identify adulteration. Studies showed that the correct rate of validation set by linear discriminant analysis and support vector machine model on full spectral were both higher than 88%, variables were significantly reduced from 312 to 8 after selecting the eight characteristic wavelengths, the correct rate of validation set by linear discriminant analysis model was up to 96.15% and support vector machine was increase to 94.87%. The results demonstrated that the model built using a attenuated total internal refraction-fourier transform infrared spectroscopy in combination with chemometric methods after selected characteristic wavelengths could be used for the identification of the adulterated syrup in the pure pineapple juice. PMID:26904809
Villa, E.
1999-07-28
Air samples from F-Canyon effluents were collected at the F-Canyon stack and transported to a laboratory at the Savannah River Technology Center (SRTC) for analysis using a Fourier transform infrared spectrometer in conjunction with a multipath cell. Air samples were collected during the decladding and acid cuts of the dissolution of the irradiated aluminum-cladded slugs. The FTIR analyses of the air samples show the presence of NO2, NO, HNO2, N2O, SF6, and 85Kr during the dissolution cycle. The concentration time profiles of these effluents corresponded with expected release rates from the F-Canyon operations.
Analysis of collagen fiber domain organization by Fourier second harmonic generation microscopy
NASA Astrophysics Data System (ADS)
Ghazaryan, Ara; Tsai, Halley F.; Hayrapetyan, Gor; Chen, Wei-Liang; Chen, Yang-Fang; Jeong, Myung Yung; Kim, Chang-Seok; Chen, Shean-Jen; Dong, Chen-Yuan
2013-03-01
We present an automated and systematic two-dimensional discrete Fourier transform (2D-FFT) approach to analyze collagen fiber organization through the use of second harmonic generation (SHG) microscopy. Average orientations of individual domains and Ising-like order parameters introduced to characterize the correlation between orientations of adjacent domains may be used to quantitatively characterize fibrous tissues. Our approach was applied to analyze tissues including rat tail tendon, mouse skin, bovine corneas, and human corneas. We also show that collagen fiber organization in normal and keratokonus human corneas may be distinguished. The current approach may be used for the quantitative differentiation of SHG collagen fiber morphology in different tissues and may be applied for diagnostic purposes.
Analytical determination of orbital elements using Fourier analysis. I. The radial velocity case
NASA Astrophysics Data System (ADS)
Delisle, J.-B.; Ségransan, D.; Buchschacher, N.; Alesina, F.
2016-05-01
We describe an analytical method for computing the orbital parameters of a planet from the periodogram of a radial velocity signal. The method is very efficient and provides a good approximation of the orbital parameters. The accuracy is mainly limited by the accuracy of the computation of the Fourier decomposition of the signal which is sensitive to sampling and noise. Our method is complementary with more accurate (and more expensive in computer time) numerical algorithms (e.g. Levenberg-Marquardt, Markov chain Monte Carlo, genetic algorithms). Indeed, the analytical approximation can be used as an initial condition to accelerate the convergence of these numerical methods. Our method can be applied iteratively to search for multiple planets in the same system.
[Analysis of different parts of scorpio by Fourier transform infrared spectroscopy].
Zhang, Sheng-Jun; Xu, Chang-Hua; Chen, Jian-Bo; Zhou, Qun; Sun, Su-Qin
2011-10-01
Fourier transform infrared (FTIR) spectroscopy and second derivative IR spectroscopy were applied to analyze and evaluate different parts of Scorpio. The second derivative IR spectra show clear differences while the origin spectra are quite similar. It was found that proteins are the dominant components in each part and the tail has distinct proteins compared to the others; fats are mainly stored in the trunk; sulfates are ubiquitous in all parts. Interestingly, the back part of the trunk of degenerative Scorpio contains some purine. It was demonstrated that FTIR spectroscopy integrated with second derivative IR spectroscopy not only can offer a fast, comprehensive and objective methodology for analyzing and evaluating the micro-differences among the various parts of same medicinal materials, but also can provide a rational guidance for medicinal and pharmacological studies. PMID:22250541
NASA Astrophysics Data System (ADS)
Watanabe, Hiroyuki
In this research, an iterative learning type courseware was made, the distribution of time scores in the courseware is gotten by the learning management system. It is a proposed method by which the distribution of time scores is changed to frequency and to power spectrum using Fourier Transform. The learning process continues until students get the passing scores and are classified by using these values, which are related to average time and the average of scores‧ square. Furthermore, the cross-correlation coefficients between the standard student and students are calculated, and delay times are analyzed. Finally, the transfer functions of some students are calculated, and the characteristics of the learning processes are analyzed.
NASA Technical Reports Server (NTRS)
Zimmerman, G. A.; Gulkis, S.
1991-01-01
The sensitivity of a matched filter-detection system to a finite-duration continuous wave (CW) tone is compared with the sensitivities of a windowed discrete Fourier transform (DFT) system and an ideal bandpass filter-bank system. These comparisons are made in the context of the NASA Search for Extraterrestrial Intelligence (SETI) microwave observing project (MOP) sky survey. A review of the theory of polyphase-DFT filter banks and its relationship to the well-known windowed-DFT process is presented. The polyphase-DFT system approximates the ideal bandpass filter bank by using as few as eight filter taps per polyphase branch. An improvement in sensitivity of approx. 3 dB over a windowed-DFT system can be obtained by using the polyphase-DFT approach. Sidelobe rejection of the polyphase-DFT system is vastly superior to the windowed-DFT system, thereby improving its performance in the presence of radio frequency interference (RFI).
Aperiodic-Fourier modal method for analysis of body-of-revolution photonic structures.
Bigourdan, Florian; Hugonin, Jean-Paul; Lalanne, Philippe
2014-06-01
Modeling the field produced by a point-like dipole with an arbitrary location in the presence of a rotationally invariant nanostructure is an important issue in the context of designing nanoantennas. This is a challenging problem, as rotational symmetry is broken when introducing a noncentered dipole. Antennas larger than the wavelength are required for directivity, whereas the dipole-antenna distance is highly subwavelength, so there are two different length scales in the problem. In this paper, we introduce an original S-matrix approach based on an aperiodic-Fourier modal method. The potential of the technique is illustrated by considering three examples. We compare our results with a finite element technique. PMID:24977369
Kaiser, Nathan K; Savory, Joshua J; McKenna, Amy M; Quinn, John P; Hendrickson, Christopher L; Marshall, Alan G
2011-09-01
Complex natural organic mixtures such as petroleum require ultrahigh mass spectral resolution to separate and identify thousands of elemental compositions. Here, we incorporate a custom-built, voltage-compensated ICR cell for Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS), based on a prior design by Tolmachev to produce optimal mass resolution. The compensated ICR cell installed in a custom-built 9.4 T FTICR mass spectrometer consists of seven cylindrical segments with axial proportions designed to generate a dc trapping potential that approaches an ideal three-dimensional axial quadrupolar potential. However, the empirically optimized compensation voltages do not correspond to the most quadrupolar trapping field. The compensation electrodes minimize variation in the reduced cyclotron frequency by balancing imperfections in the magnetic and electric field. The optimized voltages applied to compensation electrodes preserve ion cloud coherence for longer transient duration by approximately a factor of 2, enabling separation and identification of isobaric species (compounds with the same nominal mass but different exact mass) common in petroleum, such as C(3) vs SH(4) (separated by 3.4 mDa) and SH(3)(13)C vs (12)C(4) (separated by 1.1 mDa). The improved performance of the ICR cell provides more symmetric peak shape and better mass measurement accuracy. A positive ion atmospheric pressure photoionization (APPI) petroleum spectrum yields more than 26,000 assigned peaks, Fourier-limited resolving power of 800,000 at m/z 500 (6.6 s transient duration), and 124 part per billion root mean square (rms) error. The tunability of the compensation electrodes is critical for optimal performance. PMID:21838231
Introduction to Fourier Optics
ERIC Educational Resources Information Center
Huggins, Elisha
2007-01-01
Much like a physical prism, which displays the frequency components of a light wave, Fourier analysis can be thought of as a mathematical prism that can tell us what harmonics or frequency components are contained in a recording of a sound wave. We wrote the MacScope II program so that the user could not only see a plot of the harmonic amplitudes…
Gil de Prado, Elena; Rivas, Eva-María; de Silóniz, María-Isabel; Diezma, Belén; Barreiro, Pilar; Peinado, José M
2014-11-01
The colony shape of four yeast species growing on agar medium was measured for 116 days by image analysis. Initially, all the colonies are circular, with regular edges. The loss of circularity can be quantitatively estimated by the eccentricity index, Ei , calculated as the ratio between their orthogonal vertical and horizontal diameters. Ei can increase from 1 (complete circularity) to a maximum of 1.17-1.30, depending on the species. One colony inhibits its neighbour only when it has reached a threshold area. Then, Ei of the inhibited colony increases proportionally to the area of the inhibitory colony. The initial distance between colonies affects those threshold values but not the proportionality, Ei /area; this inhibition affects the shape but not the total surface of the colony. The appearance of irregularities in the edges is associated, in all the species, not with age but with nutrient exhaustion. The edge irregularity can be quantified by the Fourier index, Fi , calculated by the minimum number of Fourier coefficients that are needed to describe the colony contour with 99% fitness. An ad hoc function has been developed in Matlab v. 7.0 to automate the computation of the Fourier coefficients. In young colonies, Fi has a value between 2 (circumference) and 3 (ellipse). These values are maintained in mature colonies of Debaryomyces, but can reach values up to 14 in Saccharomyces. All the species studied showed the inhibition of growth in facing colony edges, but only three species showed edge irregularities associated with substrate exhaustion. PMID:25100432
Gao, Jingz; Ji, Zhong-Ying; Wang, Zhong-Hou; Cui, Yan
2010-04-01
Spatially modulated imaging Fourier transform spectrometer (SMIFTS) was an instrument that depended on interference, and after calibration, the reconstruction spectrum can quantificationally reflect the diffuse reflection of target under sunshine. On-board calibration of SMIFTS confirmed the change of SMIFTS according to relative spectrum calibration, inspected long-time attenuation of SMIFTS optical system, and corrected export data of SMIFTS. According to the requirement of remote sensor application, it must stay in vacuum environment for a long time. As a radiant standard, the stability of lamp-house in long time is the most important characteristic of on-board calibration system. By calculation and experimentation, analyses of on-board calibration of SMIFTS, and testing spaceflight environment characteristic of on-board calibration, the difficulty in the key parts of on-board calibration of SMIFTS such as lamp-house, spectrum filter and integrating sphere was solved. According to the radiation-time stability testing for lamp-house and optics, particle-radiation testing, environmental-mechanics testing and hot vacuum examination, good result was obtained. By whole-aperture and part-field comparative wavelength calibration, the spectrum curve and before-launch interferogram were obtained. After comparison with reconstruction spectrum under different condition, the stability and credibility of SMIFTS on-board calibration system was proved. PMID:20545151
Lorin, Chrystelle; Melin, Anne-Marie; Chenu, Jean-Patrick; Perromat, Annie; Déléris, Gérard
2004-03-01
In this study, we have investigated the postoperative plasma consequences of coral implantation into femoral condyle of rabbits. Analyses were performed using Fourier transform infrared (FT-IR) spectroscopy, a sensitive and nondestructive method, to evaluate plasma modifications one day, one week, one month, and three months after surgery. This technique showed that both surgery and implantation induced important changes of lipidic compounds one day after surgery, with a body lipolysis. Major modifications appeared one week after surgery, with a decrease of protein and saccharide contents, and an increase of amino acids accompanied by a noticeable inflammatory process. These last changes were revealed by a hierarchical classification in the 1430-1295 and 1137-1092 cm(-1) spectral regions, leading to two well-separated groups, before and one week after surgery. After a delayed time of three months and despite a substantial recovery for biomolecules such as proteins and fatty acids, some alterations are always observed, such as for amino acids, triglycerides, and glycerol. Moreover, molecules implicated in the inflammatory process had not reached their initial level. PMID:15035715
Fourier spatial frequency analysis for image classification: training the training set
NASA Astrophysics Data System (ADS)
Johnson, Timothy H.; Lhamo, Yigah; Shi, Lingyan; Alfano, Robert R.; Russell, Stewart
2016-04-01
The Directional Fourier Spatial Frequencies (DFSF) of a 2D image can identify similarity in spatial patterns within groups of related images. A Support Vector Machine (SVM) can then be used to classify images if the inter-image variance of the FSF in the training set is bounded. However, if variation in FSF increases with training set size, accuracy may decrease as the size of the training set increases. This calls for a method to identify a set of training images from among the originals that can form a vector basis for the entire class. Applying the Cauchy product method we extract the DFSF spectrum from radiographs of osteoporotic bone, and use it as a matched filter set to eliminate noise and image specific frequencies, and demonstrate that selection of a subset of superclassifiers from within a set of training images improves SVM accuracy. Central to this challenge is that the size of the search space can become computationally prohibitive for all but the smallest training sets. We are investigating methods to reduce the search space to identify an optimal subset of basis training images.
Fourier Analysis of Blazar Variability: Klein-Nishina Effects and the Jet Scattering Environment
NASA Astrophysics Data System (ADS)
Finke, Justin D.; Becker, Peter A.
2015-08-01
The strong variability of blazars can be characterized by power spectral densities (PSDs) and Fourier frequency-dependent time lags. In previous work, we created a new theoretical formalism for describing the PSDs and time lags produced via a combination of stochastic particle injection and emission via the synchrotron, synchrotron self-Compton, and external Compton (EC) processes. This formalism used the Thomson cross section and simple δ-function approximations to model the synchrotron and Compton emissivities. Here we expand upon this work, using the full Compton cross section and detailed and accurate emissivities. Our results indicate good agreement between the PSDs computed using the δ-function approximations and those computed using the accurate expressions, provided the observed photons are produced primarily by electrons with energies exceeding the lower limit of the injected particle population. Breaks are found in the PSDs at frequencies corresponding to the cooling timescales of the electrons primarily responsible for the observed emission, and the associated time lags are related to the difference in electron cooling timescales between the two energy channels, as expected. If the electron cooling timescales can be determined from the observed time lags and/or the observed EC PSDs, then one could in principle use the method developed here to determine the energy of the external seed photon source for EC, which is an important unsolved problem in blazar physics.
The Spectrum and Term Analysis of Co III Measured Using Fourier Transform and Grating Spectroscopy
NASA Astrophysics Data System (ADS)
Smillie, D. G.; Pickering, J. C.; Nave, G.; Smith, P. L.
2016-03-01
The spectrum of Co iii has been recorded in the region 1562-2564 Å (64,000 cm-1-39,000 cm-1) by Fourier transform (FT) spectroscopy, and in the region 1317-2500 Å (164,000 cm-1-40,000 cm-1) using a 10.7 m grating spectrograph with phosphor image plate detectors. The spectrum was excited in a cobalt-neon Penning discharge lamp. We classified 514 Co iii lines measured using FT spectroscopy, the strongest having wavenumber uncertainties approaching 0.004 cm-1 (approximately 0.2 mÅ at 2000 Å, or 1 part in 107), and 240 lines measured with grating spectroscopy with uncertainties between 5 and 10 mÅ. The wavelength calibration of 790 lines of Raassen & Ortí Ortin and 87 lines from Shenstone has been revised and combined with our measurements to optimize the values of all but one of the 288 previously reported energy levels. Order of magnitude reductions in uncertainty for almost two-thirds of the 3d64s and almost half of the 3d64p revised energy levels are obtained. Ritz wavelengths have been calculated for an additional 100 forbidden lines. Eigenvector percentage compositions for the energy levels and predicted oscillator strengths have been calculated using the Cowan code.
Analysis of hyper-spectral data derived from an imaging Fourier transform: A statistical perspective
Sengupta, S.K.; Clark, G.A.; Fields, D.J.
1996-01-10
Fourier transform spectrometers (FTS) using optical sensors are increasingly being used in various branches of science. Typically, a FTS generates a three-dimensional data cube with two spatial dimensions and one frequency/wavelength dimension. The number of frequency dimensions in such data cubes is generally very large, often in the hundreds, making data analytical procedures extremely complex. In the present report, the problem is viewed from a statistical perspective. A set of procedures based on the high degree of inter-channel correlation structure often present in such hyper-spectral data, has been identified and applied to an example data set of dimension 100 x 128 x 128 comprising 128 spectral bands. It is shown that in this case, the special eigen-structure of the correlation matrix has allowed the authors to extract just a few linear combinations of the channels (the significant principal vectors) that effectively contain almost all of the spectral information contained in the data set analyzed. This in turn, enables them to segment the objects in the given spatial frame using, in a parsimonious yet highly effective way, most of the information contained in the data set.
Attenuated total reflectance fourier transform infrared analysis of fly ash geopolymer gel aging.
Rees, Catherine A; Provis, John L; Lukey, Grant C; van Deventer, Jannie S J
2007-07-17
Structural changes in fly ash geopolymers activated with different sodium hydroxide and silicate concentrations are investigated using attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy over a period of 200 days. A strong correlation is found between the concentration of silicate monomer in the activating solution and the position of the main Si-O-T stretching band in the FTIR spectrum, which gives an indication of the relative changes in the gel Si/Al ratio. The FTIR spectra of geopolymer samples with activating solution concentrations of up to 1.2 M SiO2 indicate that an Al-rich gel forms before the final gel composition is reached. The time required for the system to reach a steady gel composition depends on the silicate activating solution concentration and speciation. Geopolymers activated with solutions containing predominantly high-order silicate species rapidly reach a steady gel composition without first forming an Al-rich gel. A minimum silicate monomer concentration of approximately 0.6 M is required to shift the geopolymer synthesis mechanism from hydroxide activation to silicate activation. Silicate speciation in the activating solutions also affects zeolite formation and geopolymer microstructures, with a more homogeneous microstructure and less zeolite formation observed at a higher SiO2 content. PMID:17590027
Fourier transform infrared analysis of Tamra Bhasma at different levels: A preliminary study
Chaudhari, Swapnil Y.; Rajput, Dhirajsingh S.; Galib, R.; Prajapati, Pradeep Kumar
2015-01-01
Introduction: Tamra Bhasma, one among the herbo-metallic preparations is extensively used in Ayurveda for different conditions. To make it safe to use, Tamra has to pass through a set of classical pharmaceutical procedures including a series of quenching in prescribed liquids, followed by incineration with black sulfide of mercury and herbal juice of Citrus jambhiri Lush. and corm of Amorphophallus campanulatus Linn. FTIR profiles of Tamra Bhasma at different levels is not available. Aim: To evaluate the chemical changes in Tamra Bhasma at different steps by following Fourier transform infrared (FTIR) spectroscopy. Materials and Methods: In current study, raw Tamra, intermediate samples obtained during purification, incineration and Amritikarana were analyzed using FTIR. Results: It was observed that Shodhana procedure leads in the formation of bonds between surface particles of Tamra and Shodhana media. These formed bonds on the surface of Shodhita Tamra samples gave various sharp peaks representing presence of many functional groups. Conclusion: The FTIR spectra revealed that both Bhasma samples contained organic compounds probably in the form of a complex with common functional groups like alkyl, methyl, etc., which need further studies for exact characterization of the complexes. PMID:26730144
Zhao, Ming; Li, Yu; Peng, Leilei
2014-01-01
We report a fast non-iterative lifetime data analysis method for the Fourier multiplexed frequency-sweeping confocal FLIM (Fm-FLIM) system [ Opt. Express22, 10221 ( 2014)24921725]. The new method, named R-method, allows fast multi-channel lifetime image analysis in the system’s FPGA data processing board. Experimental tests proved that the performance of the R-method is equivalent to that of single-exponential iterative fitting, and its sensitivity is well suited for time-lapse FLIM-FRET imaging of live cells, for example cyclic adenosine monophosphate (cAMP) level imaging with GFP-Epac-mCherry sensors. With the R-method and its FPGA implementation, multi-channel lifetime images can now be generated in real time on the multi-channel frequency-sweeping FLIM system, and live readout of FRET sensors can be performed during time-lapse imaging. PMID:25321778
NASA Astrophysics Data System (ADS)
Cui, Boya; Tang, Yang; Grayson, M.
2015-01-01
Compounds and heterostructures in optical devices often host multiple carrier species that contribute simultaneously to the total electrical conduction, making it difficult to distinguish the characteristics of each type. Here a Fourier-domain Mobility Spectrum Analysis (FMSA)1 is introduced to sort the conductivity contributions of different carrier species from magnetotransport measurements. Using simulated magnetotransport data from 0 to 15 T of a simple initial trial spectrum, FMSA iteratively adjusts the spectral points in either the mobility domain or its Fourier reciprocal space to fit a mobility range spanning over three orders of magnitude (μ = 670 ~ 1,000,000 cm2/V·s). With its alternating local and global adjustments, FMSA is able to recover the mobility distribution of test data, as verified in convergence plots of the total error as a function of iteration number. This technique resolves the mobility spectra as well or better than competing MSA techniques with a simple and elegant algorithm, while precisely resolving the smoothness and width of mobility peaks without artificial broadening.
Hyatt, C J; Maughan, D W
1994-01-01
A method for determining and analyzing the wing beat frequency in Diptera is presented. This method uses an optical tachometer to measure Diptera wing movement during flight. The resulting signal from the optical measurement is analyzed using a Fast Fourier Transform (FFT) technique, and the dominant frequency peak in the Fourier spectrum is selected as the wing beat frequency. Also described is a method for determining quantitatively the degree of variability of the wing beat frequency about the dominant frequency. This method is based on determination of a quantity called the Hindex, which is derived using data from the FFT analysis. Calculation of the H index allows computer-based selection of the most suitable segment of recorded data for determination of the representative wing beat frequency. Experimental data suggest that the H index can also prove useful in examining wing beat frequency variability in Diptera whose flight muscle structure has been genetically altered. Examples from Drosophila indirect flight muscle studies as well as examples of artificial data are presented to illustrate the method. This method fulfills a need for a standardized method for determining wing beat frequencies and examining wing beat frequency variability in insects whose flight muscles have been altered by protein engineering methods. PMID:7811927
Mandibular shape analysis in fossil hominins: Fourier descriptors in norma lateralis.
Lestrel, P E; Wolfe, C A; Bodt, A
2013-08-01
Biological shape can be defined as the boundary of a form in 2-space (R(2)). An earlier study (Lestrel et al., 2010, HOMO-J. Comp. Hum. Biol.) of the cranial vault found that there were statistically significant differences between each of the three groups: H. erectus, H. heidelbergensis, and H. neanderthalensis compared with H. sapiens. In contrast, there was no statistically significant difference among the first three groups. These results suggest that these three groups may have formed single evolving lineage while H. sapiens represents a separate evolutionary development. The purpose of the current research was to discern if the mandible reflected a similar pattern as the cranial vault data. This study used lateral jpeg images of the mandible. Five fossil samples were used: A. robustus (n=7), H. erectus (n=12), H. heidelbergensis (n=4), H. neanderthalensis (n=22) and H. sapiens (n=61). Each mandible image was pre-processed with Photoshop Elements. Each image was then submitted to a specially written routine that digitized the 84 points along the mandible boundary. Each mandible was fitted with elliptical Fourier functions (EFFs). Procrustes superimposition was imposed to insure minimum shape differences. The mandible results largely mirrored the earlier cranial vault study with one exception. Statistically significant results were obtained for the mandible between the H. erectus and H. neanderthalensis samples in contrast to the earlier cranial vault data. F-tests disclosed that the statistical significance was limited to the anterior symphysis of the mandible. This mosaic pattern may be explained by the reduction in prognathism with the concomitant if rudimentary development of the chin as seen in H. neanderthalensis compared to H. erectus. PMID:23769600
Dugué, Laura; Vanrullen, Rufin
2014-01-01
What are the temporal dynamics of perceptual sampling during visual search tasks, and how do they differ between a difficult (or inefficient) and an easy (or efficient) task? Does attention focus intermittently on the stimuli, or are the stimuli processed continuously over time? We addressed these questions by way of a new paradigm using periodic fluctuations of stimulus information during a difficult (color-orientation conjunction) and an easy (+ among Ls) search task. On each stimulus, we applied a dynamic visual noise that oscillated at a given frequency (2-20 Hz, 2-Hz steps) and phase (four cardinal phase angles) for 500 ms. We estimated the dynamics of attentional sampling by computing an inverse Fourier transform on subjects' d-primes. In both tasks, the sampling function presented a significant peak at 2 Hz; we showed that this peak could be explained by nonperiodic search strategies such as increased sensitivity to stimulus onset and offset. Specifically in the difficult task, however, a second, higher-frequency peak was observed at 9 to 10 Hz, with a similar phase for all subjects; this isolated frequency component necessarily entails oscillatory attentional dynamics. In a second experiment, we presented difficult search arrays with dynamic noise that was modulated by the previously obtained grand-average attention sampling function or by its converse function (in both cases omitting the 2 Hz component to focus on genuine oscillatory dynamics). We verified that performance was higher in the latter than in the former case, even for subjects who had not participated in the first experiment. This study supports the idea of a periodic sampling of attention during a difficult search task. Although further experiments will be needed to extend these findings to other search tasks, the present report validates the usefulness of this novel paradigm for measuring the temporal dynamics of attention. PMID:24525262
NASA Astrophysics Data System (ADS)
Caprioli, A.; Cigada, A.; Raveglia, D.
2007-02-01
Nowadays the power of data analysis tools like the wavelet decomposition of signals is well known and spread. On the other hand the theoretical advantages of such methods often fight with reality, when real field signals are collected and analysed: it sometimes comes out that this time-frequency approach somehow fails, demanding for a deeper insight into the kind of physical problem to be considered, and requiring a sort of "benchmark" between the traditional Fourier approach and the more recent time-frequency one. In this paper, sharply application-oriented, the possibilities offered by the wavelet techniques have been analysed: both the DSP specialist and the field engineer points of view have been joined to exploit the new approach of its best. A real problem has been considered, in which acceleration signals from a train bogie are collected and real-time analysed, to get a diagnostic tool to know the track condition of a subway line. This paper would like to look for a compromise point between complex mathematics based techniques, such as wavelet packet, sometimes hard to comprehend to the application engineer, and the physical meaning of these tools helping in fixing the real method limits. Therefore the aim is not just trying this analysis on an almost random process, like the accelerations measured on a running bogie, to locate defects, but rather a discussion on the development of the continuous and discrete wavelet transform, in comparison with the classical Fourier analysis or filter banks. Only the minimum mathematical background is provided in the text, with the needed references, to give tools fit for comprehending the physical meaning of the new tools, capable of sparing computing effort, while preserving or even improving the system effectiveness.
NASA Astrophysics Data System (ADS)
Kester, Michael; Trygstad, Marc; Chabot, Paul
2003-09-01
A unique analytical methodology has recently been developed to perform real-time, on-line chemical analysis of bath solutions in semiconductor fabrication tools. A novel, patented fiber optic sensor is used to transmit infrared light directly through the tube walls of the circulating bath solutions within the fabrication tool in a completely non-invasive, non-extractive way. The sensor simply "clips" onto the tubing, thus permitting immediate analysis of the bath composition by Fourier Transform infrared (FTIR) spectroscopy. The infrared spectrometer is capable of multiplexing up to eight "Clippir™" sensor heads to a single interferometer using fiber optic cables. The instrument can analyze almost any bath solution utilized today. The analysis is performed using the near-infrared (NIR) portion of the electromagnetic spectrum, where absorption bands related to molecular vibrations can be found. The Fourier Transform infrared spectrometer gives access to absorption bands over a wide range of frequencies (or wavelengths), and the absorptions are correlated to concentrations using a chemometric approach employing a partial least-squares algorithm. Models are generated from this approach for each chemistry to be analyzed. This paper will review the analytical technology necessary to make such measurements, and discuss the instrument performance criteria required to achieve accurate and precise measurements of bath chemistries. The ability to measure non-infrared absorbing compounds will be discussed, as will the nature of the influence of sample temperature on measurement. Issues critical to the development of robust models and their direct implementation on multiple channels and even different instruments will be considered.
Mueller, Daniela; Ferrão, Marco Flôres; Marder, Luciano; da Costa, Adilson Ben; de Cássia de Souza Schneider, Rosana
2013-01-01
The main objective of this study was to use infrared spectroscopy to identify vegetable oils used as raw material for biodiesel production and apply multivariate analysis to the data. Six different vegetable oil sources—canola, cotton, corn, palm, sunflower and soybeans—were used to produce biodiesel batches. The spectra were acquired by Fourier transform infrared spectroscopy using a universal attenuated total reflectance sensor (FTIR-UATR). For the multivariate analysis principal component analysis (PCA), hierarchical cluster analysis (HCA), interval principal component analysis (iPCA) and soft independent modeling of class analogy (SIMCA) were used. The results indicate that is possible to develop a methodology to identify vegetable oils used as raw material in the production of biodiesel by FTIR-UATR applying multivariate analysis. It was also observed that the iPCA found the best spectral range for separation of biodiesel batches using FTIR-UATR data, and with this result, the SIMCA method classified 100% of the soybean biodiesel samples. PMID:23539030
Kwon, Yong-Kook; Ahn, Myung Suk; Park, Jong Suk; Liu, Jang Ryol; In, Dong Su; Min, Byung Whan; Kim, Suk Weon
2013-01-01
To determine whether Fourier transform (FT)-IR spectral analysis combined with multivariate analysis of whole-cell extracts from ginseng leaves can be applied as a high-throughput discrimination system of cultivation ages and cultivars, a total of total 480 leaf samples belonging to 12 categories corresponding to four different cultivars (Yunpung, Kumpung, Chunpung, and an open-pollinated variety) and three different cultivation ages (1 yr, 2 yr, and 3 yr) were subjected to FT-IR. The spectral data were analyzed by principal component analysis and partial least squares-discriminant analysis. A dendrogram based on hierarchical clustering analysis of the FT-IR spectral data on ginseng leaves showed that leaf samples were initially segregated into three groups in a cultivation age-dependent manner. Then, within the same cultivation age group, leaf samples were clustered into four subgroups in a cultivar-dependent manner. The overall prediction accuracy for discrimination of cultivars and cultivation ages was 94.8% in a cross-validation test. These results clearly show that the FT-IR spectra combined with multivariate analysis from ginseng leaves can be applied as an alternative tool for discriminating of ginseng cultivars and cultivation ages. Therefore, we suggest that this result could be used as a rapid and reliable F1 hybrid seed-screening tool for accelerating the conventional breeding of ginseng. PMID:24558311
Gao, Wenjing; Huyen, Nguyen Thi Thanh; Loi, Ho Sy; Kemao, Qian
2009-12-01
In optical interferometers, fringe projection systems, and synthetic aperture radars, fringe patterns are common outcomes and usually degraded by unavoidable noises. The presence of noises makes the phase extraction and phase unwrapping challenging. Windowed Fourier transform (WFT) based algorithms have been proven to be effective for fringe pattern analysis to various applications. However, the WFT-based algorithms are computationally expensive, prohibiting them from real-time applications. In this paper, we propose a fast parallel WFT-based library using graphics processing units and computer unified device architecture. Real-time WFT-based algorithms are achieved with 4 frames per second in processing 256x256 fringe patterns. Up to 132x speedup is obtained for WFT-based algorithms using NVIDIA GTX295 graphics card than sequential C in quad-core 2.5GHz Intel(R)Xeon(R) CPU E5420. PMID:20052242
Mackie, David M.; Jahnke, Justin P.; Benyamin, Marcus S.; Sumner, James J.
2016-01-01
The standard methodologies for quantitative analysis (QA) of mixtures using Fourier transform infrared (FTIR) instruments have evolved until they are now more complicated than necessary for many users’ purposes. We present a simpler methodology, suitable for widespread adoption of FTIR QA as a standard laboratory technique across disciplines by occasional users.•Algorithm is straightforward and intuitive, yet it is also fast, accurate, and robust.•Relies on component spectra, minimization of errors, and local adaptive mesh refinement.•Tested successfully on real mixtures of up to nine components. We show that our methodology is robust to challenging experimental conditions such as similar substances, component percentages differing by three orders of magnitude, and imperfect (noisy) spectra. As examples, we analyze biological, chemical, and physical aspects of bio-hybrid fuel cells. PMID:26977411
Fujii, Satoshi; Sato, Shinobu; Fukuda, Keisuke; Okinaga, Toshinori; Ariyoshi, Wataru; Usui, Michihiko; Nakashima, Keisuke; Nishihara, Tatsuji; Takenaka, Shigeori
2016-01-01
Diagnosis of periodontal disease by Fourier transform infrared (FT-IR) microscopic technique was achieved for saliva samples. Twenty-two saliva samples, collected from 10 patients with periodontal disease and 12 normal volunteers, were pre-processed and analyzed by FT-IR microscopy. We found that the periodontal samples showed a larger raw IR spectrum than the control samples. In addition, the shape of the second derivative spectrum was clearly different between the periodontal and control samples. Furthermore, the amount of saliva content and the mixture ratio were different between the two samples. Partial least squares discriminant analysis was used for the discrimination of periodontal samples based on the second derivative spectrum. The leave-one-out cross-validation discrimination accuracy was 94.3%. Thus, these results show that periodontal disease may be diagnosed by analyzing saliva samples with FT-IR microscopy. PMID:26860570
NASA Astrophysics Data System (ADS)
Rajiv, P.; Rajeshwari, Sivaraj; Venckatesh, Rajendran
2013-12-01
Fourier transform infrared spectroscopy (FT-IR) and Gas chromatography-mass spectroscopy have been carried out to investigate the chemical composition of Parthenium mediated vermicompost. Four different concentrations of Parthenium and cow dung mixtures were vermicomposted using the earthworms (Eudrilus eugeniae). FT-IR spectra reveal the absence of Parthenin toxin (sesquiterpene lactone) and phenols in vermicompost which was obtained from high concentration of cow dung mixed treatments. GC-MS analysis shows no phenolic compounds and predominant level of intermediate metabolites such as 4,8,12,16-Tetramethylheptadecan-4-olide (7.61%), 2-Pentadecanone, 6,10,14-trimethyl- (5.29%) and Methyl 16-methyl-heptadecanoate (4.69%) during the vermicomposting process. Spectral results indicated that Parthenin toxin and phenols can be eradicated via vermicomposting if mixed with appropriate quantity of cow dung.
Samlan, C T; Naik, Dinesh N; Viswanathan, Nirmal K
2016-01-01
Discovered in 1813, the conoscopic interference pattern observed due to light propagating through a crystal, kept between crossed polarizers, shows isochromates and isogyres, respectively containing information about the dynamic and geometric phase acquired by the beam. We propose and demonstrate a closed-fringe Fourier analysis method to disentangle the isogyres from the isochromates, leading us to the azimuthally varying geometric phase and its manifestation as isogyres. This azimuthally varying geometric phase is shown to be the underlying mechanism for the spin-to-orbital angular momentum conversion observed in a diverging optical field propagating through a z-cut uniaxial crystal. We extend the formalism to study the optical activity mediated uniaxial-to-biaxial transformation due to a weak transverse electric field applied across the crystal. Closely associated with the phase and polarization singularities of the optical field, the formalism enables us to understand crystal optics in a new way, paving the way to anticipate several emerging phenomena. PMID:27625210
NASA Astrophysics Data System (ADS)
Brüning, Rainer; Scholz, Peter; Ondruschka, Bernd
2005-07-01
The construction of a stage-II-screening device for heterogeneous catalysts in gas phase reactions under ambient pressure is described. The concentrations of the reaction products are determined by Fourier transform infrared analysis in combination with a chemometric interpretation of the obtained spectra. Thus, fast high-precision product analyses with complete mass balances are feasible, within the limits of accuracy of the measurements. The device is designed to screen up to 17 catalysts in one testing cycle. It is possible to determine temperature-conversion-selectivity dependencies as well as long-term measurements under constant conditions. With the help of the device described, the catalytic properties of new materials were parallel tested for the oxidative dehydrogenation of isopropanol.
Rajiv, P; Rajeshwari, Sivaraj; Venckatesh, Rajendran
2013-12-01
Fourier transform infrared spectroscopy (FT-IR) and Gas chromatography-mass spectroscopy have been carried out to investigate the chemical composition of Parthenium mediated vermicompost. Four different concentrations of Parthenium and cow dung mixtures were vermicomposted using the earthworms (Eudrilus eugeniae). FT-IR spectra reveal the absence of Parthenin toxin (sesquiterpene lactone) and phenols in vermicompost which was obtained from high concentration of cow dung mixed treatments. GC-MS analysis shows no phenolic compounds and predominant level of intermediate metabolites such as 4,8,12,16-Tetramethylheptadecan-4-olide (7.61%), 2-Pentadecanone, 6,10,14-trimethyl- (5.29%) and Methyl 16-methyl-heptadecanoate (4.69%) during the vermicomposting process. Spectral results indicated that Parthenin toxin and phenols can be eradicated via vermicomposting if mixed with appropriate quantity of cow dung. PMID:23998948
NASA Astrophysics Data System (ADS)
Sukuta, Sydney; Bruch, Reinhard F.
2002-05-01
The goal of this study is to test the feasibility of using noise factor/eigenvector bands as general clinical analytical tools for diagnoses. We developed a new technique, Noise Band Factor Cluster Analysis (NBFCA), to diagnose benign tumors via their Fourier transform IR fiber optic evanescent wave spectral data for the first time. The middle IR region of human normal skin tissue and benign and melanoma tumors, were analyzed using this new diagnostic technique. Our results are not in full-agreement with pathological classifications hence there is a possibility that our approaches could complement or improve these traditional classification schemes. Moreover, the use of NBFCA make it much easier to delineate class boundaries hence this method provides results with much higher certainty.
NASA Astrophysics Data System (ADS)
Civco, Daniel L.; Witharana, Chandi
2012-10-01
Pan-sharpening of moderate resolution multispectral remote sensing data with those of a higher spatial resolution is a standard practice in remote sensing image processing. This paper suggests a method by which the spatial properties of resolution merge products can be assessed. Whereas there are several accepted metrics, such as correlation and root mean square error, for quantifying the spectral integrity of fused images, relative to the original multispectral data, there is less agreement on a means by which to assess the spatial properties, relative to the original higher-resolution, pansharpening data. In addition to qualitative, visual, and somewhat subjective evaluation, quantitative measures used have included correlations between high-pass filtered panchromatic and fused images, gradient analysis, wavelet analysis, among others. None of these methods, however, fully exploits the spatial and structural information contained in the original high resolution and fused images. This paper proposes the use of the Fourier transform as a means to quantify the degree to which a fused image preserves the spatial properties of the pan-sharpening high resolution data. A highresolution 8-bit panchromatic image was altered to produce a set of nine different test images, as well as a random image. The Fourier Magnitude (FM) image was calculated for each of the datasets and compared via FM to FM image correlation. Furthermore, the following edge detection algorithms were applied to the original and altered images: (a) Canny; (b) Sobel; and (c) Laplacian. These edge-filtered images were compared, again by way of correlation, with the original edge-filtered panchromatic image. Results indicate that the proposed method of using FTMI as a means of assessing the spatial fidelity of high-resolution imagery used in the data fusion process outperforms the correlations produced by way of comparing edge-enhanced images.
Zhang, Jie; Pan, Ruru; Gao, Weidong
2015-02-01
Yarn density measurement is a significant part of yarn-dyed fabric analysis, traditionally based on reflective image analysis. In this paper, utilizing fabric light transmittance, a method for two-dimensional discrete Fourier transform (2D DFT) analysis on the transmission fabric image is developed for fabric density inspection. First, the power spectrum is generated from the fabric image by a 2D DFT. Next, the yarn skew angles are detected based on the power spectrum analysis. Then the fabric image is reconstructed by an inverse 2D DFT. Finally, projection curves are generated from the reconstructed images and the number of yarns is counted according to the peaks and valleys to obtain the fabric density. Through a comparison between analysis on the reflective and transmission images of multiple-color fabrics, it is proved that the latter method can segment the yarns with more satisfactory accuracy. Furthermore, the experimental and theoretical analyses demonstrate that the proposed method is effective for the density inspection of yarn-dyed fabrics with good robustness and great accuracy. PMID:25967813
Zhu, Ying; Tan, Tuck Lee
2016-04-15
An effective and simple analytical method using Fourier transform infrared (FTIR) spectroscopy to distinguish wild-grown high-quality Ganoderma lucidum (G. lucidum) from cultivated one is of essential importance for its quality assurance and medicinal value estimation. Commonly used chemical and analytical methods using full spectrum are not so effective for the detection and interpretation due to the complex system of the herbal medicine. In this study, two penalized discriminant analysis models, penalized linear discriminant analysis (PLDA) and elastic net (Elnet),using FTIR spectroscopy have been explored for the purpose of discrimination and interpretation. The classification performances of the two penalized models have been compared with two widely used multivariate methods, principal component discriminant analysis (PCDA) and partial least squares discriminant analysis (PLSDA). The Elnet model involving a combination of L1 and L2 norm penalties enabled an automatic selection of a small number of informative spectral absorption bands and gave an excellent classification accuracy of 99% for discrimination between spectra of wild-grown and cultivated G. lucidum. Its classification performance was superior to that of the PLDA model in a pure L1 setting and outperformed the PCDA and PLSDA models using full wavelength. The well-performed selection of informative spectral features leads to substantial reduction in model complexity and improvement of classification accuracy, and it is particularly helpful for the quantitative interpretations of the major chemical constituents of G. lucidum regarding its anti-cancer effects. PMID:26827180
NASA Astrophysics Data System (ADS)
Zhu, Ying; Tan, Tuck Lee
2016-04-01
An effective and simple analytical method using Fourier transform infrared (FTIR) spectroscopy to distinguish wild-grown high-quality Ganoderma lucidum (G. lucidum) from cultivated one is of essential importance for its quality assurance and medicinal value estimation. Commonly used chemical and analytical methods using full spectrum are not so effective for the detection and interpretation due to the complex system of the herbal medicine. In this study, two penalized discriminant analysis models, penalized linear discriminant analysis (PLDA) and elastic net (Elnet),using FTIR spectroscopy have been explored for the purpose of discrimination and interpretation. The classification performances of the two penalized models have been compared with two widely used multivariate methods, principal component discriminant analysis (PCDA) and partial least squares discriminant analysis (PLSDA). The Elnet model involving a combination of L1 and L2 norm penalties enabled an automatic selection of a small number of informative spectral absorption bands and gave an excellent classification accuracy of 99% for discrimination between spectra of wild-grown and cultivated G. lucidum. Its classification performance was superior to that of the PLDA model in a pure L1 setting and outperformed the PCDA and PLSDA models using full wavelength. The well-performed selection of informative spectral features leads to substantial reduction in model complexity and improvement of classification accuracy, and it is particularly helpful for the quantitative interpretations of the major chemical constituents of G. lucidum regarding its anti-cancer effects.
Graichen, Uwe; Eichardt, Roland; Fiedler, Patrique; Strohmeier, Daniel; Zanow, Frank; Haueisen, Jens
2015-01-01
Important requirements for the analysis of multichannel EEG data are efficient techniques for signal enhancement, signal decomposition, feature extraction, and dimensionality reduction. We propose a new approach for spatial harmonic analysis (SPHARA) that extends the classical spatial Fourier analysis to EEG sensors positioned non-uniformly on the surface of the head. The proposed method is based on the eigenanalysis of the discrete Laplace-Beltrami operator defined on a triangular mesh. We present several ways to discretize the continuous Laplace-Beltrami operator and compare the properties of the resulting basis functions computed using these discretization methods. We apply SPHARA to somatosensory evoked potential data from eleven volunteers and demonstrate the ability of the method for spatial data decomposition, dimensionality reduction and noise suppression. When employing SPHARA for dimensionality reduction, a significantly more compact representation can be achieved using the FEM approach, compared to the other discretization methods. Using FEM, to recover 95% and 99% of the total energy of the EEG data, on average only 35% and 58% of the coefficients are necessary. The capability of SPHARA for noise suppression is shown using artificial data. We conclude that SPHARA can be used for spatial harmonic analysis of multi-sensor data at arbitrary positions and can be utilized in a variety of other applications. PMID:25885290
Chagovets, Vtaliy; Kononikhin, Aleksey; Starodubtseva, Nataliia; Kostyukevich, Yury; Popov, Igor; Frankevich, Vladimir; Nikolaev, Eugene
2016-01-01
The importance of high-resolution mass spectrometry for the correct data interpretation of a direct tissue analysis is demonstrated with an example of its clinical application for an endometriosis study. Multivariate analysis of the data discovers lipid species differentially expressed in different tissues under investigation. High-resolution mass spectrometry allows unambiguous separation of peaks with close masses that correspond to proton and sodium adducts of phosphatidylcholines and to phosphatidylcholines differing in double bond number. PMID:27553733
Trillo, Cristina; Doval, Angel F; Mendoza-Santoyo, Fernando; Pérez-López, Carlos; de la Torre-Ibarra, Manuel; Deán, J Luis
2009-09-28
The combination of a high-speed TV holography system and a 3D Fourier-transform data processing is proposed for the analysis of multimode vibrations in plates. The out-of-plane displacement of the object under generic vibrational excitation is resolved in time by the fast acquisition rate of a high-speed camera, and recorded in a sequence of interferograms with spatial carrier. A full-field temporal history of the multimode vibration is thus obtained. The optical phase of the interferograms is extracted and subtracted from the phase of a reference state to yield a sequence of optical phase-change maps. Each map represents the change undergone by the object between any given state and the reference state. The sequence of maps is a 3D array of data (two spatial dimensions plus time) that is processed with a 3D Fourier-transform algorithm. The individual vibration modes are separated in the 3D frequency space due to their different vibration frequencies and, to a lesser extent, to the different spatial frequencies of the mode shapes. The contribution of each individual mode (or indeed the superposition of several modes) to the dynamic behaviour of the object can then be separated by means of a bandpass filter (or filters). The final output is a sequence of complex-valued maps that contain the full-field temporal history of the selected mode (or modes) in terms of its mechanical amplitude and phase. The proof-of-principle of the technique is demonstrated with a rectangular, fully clamped, thin metal plate vibrating simultaneously in several of its natural resonant frequencies under white-noise excitation. PMID:19907591
Wagoner, J.L.; Younker, J.L.
1982-03-01
Two-dimensional quartz grain shape was used to characterize sand grains from different source areas in the Owens Valley of eastern California. Combining a mathematical description of the grain outline and multivariate discriminant analysis, we have shown that quartz from clastic source rocks has a distinctive imprint when compared to samples from granitic, volcanic, or mixed fluvial source areas. Alternatively, quartz provided by a granitic source could equally well have been interpreted as if it were derived from any of the other sources considered. This study provides a standard of comparison for further analysis of sediment deposited in arid alluvial environments.
Freel, Christopher D; Gilliland, Kurt O; Mekeel, Harold E; Giblin, Frank J; Costello, M Joseph
2003-04-01
The structural characteristics of differentiated fiber cells in control and hyperbaric oxygen (HBO)-treated guinea pig lenses were examined by transmission electron microscopy (TEM). Emphasis was placed on cell damage, membrane integrity, and cytoplasmic texture. Given the faint gross opacities observed in HBO-treated lenses in previous studies, it was hypothesized that subtle but significant morphological differences due to oxidative damage exist between control and treated animals. Experimental animals received either 70 or 85 treatments with HBO (2.5 atm of 100% O(2) for 2.5 hr, 3 times per week for 5-7 months). All specimens were obtained within 24 hr of death. Freshly cut Vibratome lens sections were fixed and processed for low and high-magnification thin-section TEM analysis. Cytoplasmic texture was analyzed using Fourier and autocorrelation image processing techniques. Low-magnification analysis revealed relatively insignificant differences in general appearance between the fiber cells of the inner fetal and embryonic nuclei in control and HBO-treated guinea pigs. Both groups demonstrated cells of similar morphology with equivalent membrane complexity and homogeneous cytoplasmic texture. Evidence of any major cellular damage or extracellular space debris was not obvious. High-magnification analysis of the cytoplasm of the treated lenses exhibited a mild, yet detectable increase in texture compared with controls and was confirmed by Fourier analysis. Cytoplasmic texture increased in complexity with additional treatments. The absence of major cellular damage in the lenses of HBO-treated animals suggests a less conspicuous source of light scattering. The small changes in cytoplasmic organization observed between treated and control animals may entirely account for the increase in nuclear light scattering observed by slit lamp. The results obtained with this guinea pig/HBO model parallel many of the morphological data associated with human nuclear cataracts. The
Chen, L; Carpita, N C; Reiter, W D; Wilson, R H; Jeffries, C; McCann, M C
1998-11-01
We have developed a rapid method to screen large numbers of mutant plants for a broad range of cell wall phenotypes using Fourier transform infrared (FTIR) microspectroscopy of leaves. We established and validated a model that can discriminate between the leaves of wild-type and a previously defined set of cell-wall mutants of Arabidopsis. Exploratory principal component analysis indicated that mutants deficient in different cell-wall sugars can be distinguished from each other. Discrimination of cell-wall mutants from wild-type was independent of variability in starch content or additional unrelated mutations that might be present in a heavily mutagenised population. We then developed an analysis of FTIR spectra of leaves obtained from over 1000 mutagenised flax plants, and selected 59 plants whose spectral variation from wild-type was significantly out of the range of a wild-type population, determined by Mahalanobis distance. Cell wall sugars from the leaves of selected putative mutants were assayed by gas chromatography-mass spectrometry and 42 showed significant differences in neutral sugar composition. The FTIR spectra indicated that six of the remaining 17 plants have altered ester or protein content. We conclude that linear discriminant analysis of FTIR spectra is a robust method to identify a broad range of structural and architectural alterations in cell walls, appearing as a consequence of developmental regulation, environmental adaptation or genetic modification. PMID:9881159
Texture Analysis of the Epidermis Based on Fast Fourier Transformation in Sjögren-Larsson Syndrome
Auada, Mariam P; Adam, Randall L.; Leite, Neucimar J.; Puzzi, Maria B.; Cintra, Maria L.; Rizzo, William B.; Metze, Konradin
2011-01-01
OBJECTIVE To investigate whether image analysis of routine hematoxylin-eosin (H-E) skin sections usingfast Fourier transformation (FFT) could detect structural alterations in patients with Sjögren-Larsson syndrome (SLS) diagnosed by molecular biology. STUDY DESIGN Skin punch biopsies of 9 patients with SLS and 17 healthy volunteers were obtained. Digital images of routine histologic sections were taken, and their gray scale luminance was analyzed by FFT. The inertia values were determined for different ranges of the spatial frequencies in the vertical and horizontal direction. To get an estimation of anisotropy, we calculated the resultant vector of the designated frequency ranges. RESULTS In the prickle cell layer, SLS patients showed more intense amplitudes in spatial structures with periods between 1.2 and 3.6 µm in the vertical direction, which correlated in part with accentuated nuclei and nucleoli and perinucleolar halos in the H-E sections. In a linear discriminant analysis, the variables derived from the FFT images correctly discriminated 84.6% of the patients. Texture features derived from the gray level co-occurrence matrix were not able to separate the groups. CONCLUSION Exploratory texture analysis by FFT was able to detect discrete alterations in the prickle cell layer in routine light microscopy slides of SLS patients. The structural changes identified by FFT may be related to abnormal cellular components associated with aberrant lipid metabolism. PMID:16927642
NASA Astrophysics Data System (ADS)
Afanasyeva, Natalia I.; Welser, Leslie; Bruch, Reinhard F.; Kano, Angelique; Makhine, Volodymyr
1999-10-01
A new infrared (IR) interferometric method has been developed in conjunction with low-loss, flexible optical fibers, sensors, and probes. This combination of fiber optical sensors and Fourier Transform (FT) spectrometers can be applied to many fields, including (1) noninvasive medical diagnostics of cancer and other different diseases in vivo, (2) minimally invasive bulk diagnostics of tissue, (3) remote monitoring of tissue, chemical processes, and environment, (4) surface analysis of polymers and other materials, (5) characterization of the quality of food, pharmacological products, cosmetics, paper, and other wood-related products, as well as (6) agricultural, forensic, geological, mining, and archeological field measurements. In particular, our nondestructive, fast, compact, portable, remote and highly sensitive diagnostics tools are very promising for subsurface analysis at the molecular level without sample preparation. For example, this technique is ideal for different types of soft porous foams, rough polymers, and rock surfaces. Such surfaces, as well as living tissue, are very difficult to investigate by traditional FTIR methods. We present here FEW-FTIR spectra of polymers, banana and grapefruit peels, and living tissues detected directly at surfaces. In addition, results on the vibrational spectral analysis of normal and pathological skin tissue in the region of 850 - 4000 cm-1 are discussed.
Kolmogorov-Smirnov like test for time-frequency Fourier spectrogram analysis in LISA Pathfinder
NASA Astrophysics Data System (ADS)
Ferraioli, Luigi; Armano, Michele; Audley, Heather; Congedo, Giuseppe; Diepholz, Ingo; Gibert, Ferran; Hewitson, Martin; Hueller, Mauro; Karnesis, Nikolaos; Korsakova, Natalia; Nofrarias, Miquel; Plagnol, Eric; Vitale, Stefano
2015-03-01
A statistical procedure for the analysis of time-frequency noise maps is presented and applied to LISA Pathfinder mission synthetic data. The procedure is based on the Kolmogorov-Smirnov like test that is applied to the analysis of time-frequency noise maps produced with the spectrogram technique. The influence of the finite size windowing on the statistic of the test is calculated with a Monte Carlo simulation for 4 different windows type. Such calculation demonstrate that the test statistic is modified by the correlations introduced in the spectrum by the finite size of the window and by the correlations between different time bins originated by overlapping between windowed segments. The application of the test procedure to LISA Pathfinder data demonstrates the test capability of detecting non-stationary features in a noise time series that is simulating low frequency non-stationary noise in the system.
Mass Spectrometry and Fourier Transform Infrared Spectroscopy for Analysis of Biological Materials
Anderson, Timothy J.
2014-12-01
Time-of-flight mass spectrometry along with statistical analysis was utilized to study metabolic profiles among rats fed resistant starch (RS) diets. Fischer 344 rats were fed four starch diets consisting of 55% (w/w, dbs) starch. A control starch diet consisting of corn starch was compared against three RS diets. The RS diets were high-amylose corn starch (HA7), HA7 chemically modified with octenyl succinic anhydride, and stearic-acid-complexed HA7 starch. A subgroup received antibiotic treatment to determine if perturbations in the gut microbiome were long lasting. A second subgroup was treated with azoxymethane (AOM), a carcinogen. At the end of the eight week study, cecal and distal-colon contents samples were collected from the sacrificed rats. Metabolites were extracted from cecal and distal colon samples into acetonitrile. The extracts were then analyzed on an accurate-mass time-of-flight mass spectrometer to obtain their metabolic profile. The data were analyzed using partial least-squares discriminant analysis (PLS-DA). The PLS-DA analysis utilized a training set and verification set to classify samples within diet and treatment groups. PLS-DA could reliably differentiate the diet treatments for both cecal and distal colon samples. The PLS-DA analyses of the antibiotic and no antibiotic treated subgroups were well classified for cecal samples and modestly separated for distal-colon samples. PLS-DA analysis had limited success separating distal colon samples for rats given AOM from those not treated; the cecal samples from AOM had very poor classification. Mass spectrometry profiling coupled with PLS-DA can readily classify metabolite differences among rats given RS diets.
Analysis of the nutritional status of algae by Fourier transform infrared chemical imaging
NASA Astrophysics Data System (ADS)
Hirschmugl, Carol J.; Bayarri, Zuheir-El; Bunta, Maria; Holt, Justin B.; Giordano, Mario
2006-09-01
A new non-destructive method to study the nutritional status of algal cells and their environments is demonstrated. This approach allows rapid examination of whole cells without any or little pre-treatment providing a large amount of information on the biochemical composition of cells and growth medium. The method is based on the analysis of a collection of infrared (IR) spectra for individual cells; each spectrum describes the biochemical composition of a portion of a cell; a complete set of spectra is used to reconstruct an image of the entire cell. To obtain spatially resolved information synchrotron radiation was used as a bright IR source. We tested this method on the green flagellate Euglena gracilis; a comparison was conducted between cells grown in nutrient replete conditions (Type 1) and on cells allowed to deplete their medium (Type 2). Complete sets of spectra for individual cells of both types were analyzed with agglomerative hierarchical clustering, leading to distinct clusters representative of the two types of cells. The average spectra for the clusters confirmed the similarities between the clusters and the types of cells. The clustering analysis, therefore, allows the distinction of cells of the same species, but with different nutritional histories. In order to facilitate the application of the method and reduce manipulation (washing), we analyzed the cells in the presence of residual medium. The results obtained showed that even with residual medium the outcome of the clustering analysis is reliable. Our results demonstrate the applicability FTIR microspectroscopy for ecological and ecophysiological studies.
NASA Astrophysics Data System (ADS)
Guerrero, Andres; Lerno, Larry; Barile, Daniela; Lebrilla, Carlito B.
2015-03-01
Bovine κ-caseinoglycomacropeptide (GMP) is a highly modified peptide from κ-casein produced during the cheese making process. The chemical nature of GMP makes analysis by traditional proteomic approaches difficult, as the peptide bears a strong net negative charge and a variety of post-translational modifications. In this work, we describe the use of electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS) for the top-down analysis of GMP. The method allows the simultaneous detection of different GMP forms that result from the combination of amino acid genetic variations and post-translational modifications, specifically phosphorylation and O-glycosylation. The different GMP forms were identified by high resolution mass spectrometry in both negative and positive mode and confirmation was achieved by tandem MS. The results showed the predominance of two genetic variants of GMP that occur as either mono- or bi-phosphorylated species. Additionally, these four forms can be modified with up to two O-glycans generally sialylated. The results demonstrate the presence of glycosylated, bi-phosphorylated forms of GMP never described before.
Zhou, Xibin; Shi, Quan; Zhang, Yahe; Zhao, Suoqi; Zhang, Rui; Chung, Keng H; Xu, Chunming
2012-04-01
A novel technique was developed for characterization of saturated hydrocarbons. Linear alkanes were selectively oxidized to ketones by ruthenium ion catalyzed oxidation (RICO). Branched and cyclic alkanes were oxidized to alcohols and ketones. The ketones were then reduced to alcohols by lithium aluminum hydride (LiAlH(4)). The monohydric alcohols (O(1)) in the products obtained from the RICO and RICO-LiAlH(4) reduction reactions were characterized using negative-ion electrospray ionization (ESI) Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS) for identification of iso-paraffins, acyclic paraffins and cyclic paraffins. Various model saturated compounds were used to determine the RICO reaction and ionization selectivity. The results from the FTICR MS analysis on the petroleum distillates derived saturated fraction were in agreement with those from field ionization gas chromatography time-of-flight mass spectrometry (FI GC-TOF MS) analysis. The technique was also used to characterize a petroleum vacuum residue (VR) derived saturates. The results showed that the saturated molecules in the VR contained up to 11 cyclic rings, and the maximum carbon number was up to 92. PMID:22424498
Amateis, P.G.
1984-01-01
High performance liquid chromatographic separations employing on-line flow cell Fourier transform infrared spectroscopic detection were developed for polar compounds including phenols, alcohols, amines and azaarenes. Detection by FTIR gave information concerning hydrogen bonding and solvent effects occurring during the separations in addition to giving structural information about eluted species to aid in identification. Both analytical size and microbore normal phase columns were employed. Such experimental considerations as column overload, injected minimum detectable quantities, the use of analytical vs. microbore columns and flow cell pathlength were examined. The developed HPLC-FTIR systems were applied to the analysis of several coal liquefaction samples for heteroatom content. Confirmatory and additional information concerning the samples were provided by field ionization mass spectrometry, gas chromatography/mass spectrometry and reversed phase liquid chromatography employing UV detection. An equation relating reversed phase retention times to structural parameters was developed and applied to the analysis of the coal-derived samples. Two process solvents were found to contain primarily alkyl-substituted phenols in addition to azaarenes such as pyridine and quinoline. Some non-distillable coal-derived samples were found to contain azaarenes such as alkyl quinolines. Evidence was also found concerning the presence of hydroxy-pyridine type compounds and the incorporation of process solvent molecules into the coal structure during liquefaction.
The use of Fourier transform (FT) surface-enhanced Raman scattering for biochemical analysis
NASA Astrophysics Data System (ADS)
Jeffers, Robert Butler
Surface-enhanced Raman scattering (SERS) is a powerful spectroscopic technique that has created exciting opportunities in the field of bioanalytical chemistry, where it combines ultrasensitive detection of biologically relevant molecules with vibrational spectroscopy. Due to the difficulties in preparing reproducible SERS active substrates, SERS has been mainly used as a qualitative tool. In order for SERS to be utilized as a viable tool for quantitative analysis, simple, facile SERS substrates which generate clean, highly reproducible signals must be developed. This dissertation deals with the evaluation of three different methods of SERS that led to the development of a novel substrate for the analysis of biological molecules. In this dissertation, I demonstrated the generation of a SERS signal from pyridine adsorbed to the surface of a roughened silver electrode. The Raman signal was detected utilizing a remote fiber optic probe dispersive Raman instrument. The necessary parameters for generating the optimal SERS signal were established. The SERS spectrum of pyridine was successfully characterized. The synthesis of silver colloid solutions for use as a SERS active substrate was demonstrated. Two different synthetic methods were utilized and the conditions for optimal SERS signal strength were established. SERS signals from solutions of tryptophan were successfully generated and detected using an FT-Raman spectrometer. In this dissertation. I report the successful chemical deposition of a thin silver film on the surface of a quartz/glass fiber filter for use as a SERS active substrate. The successful detection of the SERS signal of solutions of phenylalanine and tryptophan utilizing the silver-coated filters and a FT-Raman instrument was demonstrated. Significant progress was made to develop a quantifiable SERS method utilizing the silver-coated filters. The silver-coated filter SERS method presented here is a novel and promising method for biochemical analysis
Polyimide analysis using diffuse reflectance-FTIR. [Fourier Transform IR Spectroscopy
NASA Technical Reports Server (NTRS)
Young, P. R.; Chang, A. C.
1985-01-01
The thermal imidization of a number of polyimide precursors in the form of powders, films, and prepregs was examined by an in situ diffuse reflectance-FTIR technique where infrared spectra were determined while the material was being heated. An analysis of these spectra revealed that, with the exception of one water soluble adhesive, each precursor developed an anhydride band around 1850 cm/cu during imidization. This band diminished in intensity during final stages of cure. Efforts were made to quantify the amount of anhydride in several samples. Evidence obtained could be interpreted to mean that poly(amic acid) resins undergo an initial reduction in molecular weight during imidization before recombining to achieve their ultimate molecular weights as polyimides. Several reports in the literature are cited to support this interpretation. This report serves both to document anhydride formation during imidization and to increase our fundamental understanding of how polyimides cure.
NASA Technical Reports Server (NTRS)
Lauer, J. L.; King, V. W.
1979-01-01
A far-infrared interferometer was converted into an emission microspectrophotometer for surface analysis. To cover the mid-infrared as well as the far-infrared the Mylar beamsplitter was made replaceable by a germanium-coated salt plate, and the Moire fringe counting system used to locate the moveable Michelson mirror was improved to read 0.5 micron of mirror displacement. Digital electronics and a dedicated minicomputer were installed for data collection and processing. The most critical element for the recording of weak emission spectra from small areas was, however, a reflecting microscope objective and phase-locked signal detection with simultaneous referencing to a blackbody source. An application of the technique to lubrication problems is shown.
Fourier Series Applications in Multitemporal Remote Sensing Analysis using Landsat Data
NASA Astrophysics Data System (ADS)
Brooks, Evan Beren
Researchers now have unprecedented access to free Landsat data, enabling detailed monitoring of the Earth's land surface and vegetation. There are gaps in the data, due in part to cloud cover. The gaps are aperiodic and localized, forcing any detailed multitemporal analysis based on Landsat data to compensate. Harmonic regression approximates Landsat data for any point in time with minimal training images and reduced storage requirements. In two study areas in North Carolina, USA, harmonic regression approaches were least as good at simulating missing data as STAR-FM for images from 2001. Harmonic regression had an R2 ≥ 0.9 over three quarters of all pixels. It gave the highest R2predicted values on two thirds of the pixels. Applying harmonic regression with the same number of harmonics to consecutive years yielded an improved fit, R2 ≥ 0.99 for most pixels. We next demonstrate a change detection method based on exponentially weighted moving average (EWMA) charts of harmonic residuals. In the process, a data-driven cloud filter is created, enabling use of partially clouded data. The approach is shown capable of detecting thins and subtle forest degradations in Alabama, USA, considerably finer than the Landsat spatial resolution in an on-the-fly fashion, with new images easily incorporated into the algorithm. EWMA detection accurately showed the location, timing, and magnitude of 85% of known harvests in the study area, verified by aerial imagery. We use harmonic regression to improve the precision of dynamic forest parameter estimates, generating a robust time series of vegetation index values. These values are classified into strata maps in Alabama, USA, depicting regions of similar growth potential. These maps are applied to Forest Service Forest Inventory and Analysis (FIA) plots, generating post-stratified estimates of static and dynamic forest parameters. Improvements to efficiency for all parameters were such that a comparable random sample would require
NASA Astrophysics Data System (ADS)
Benetti, Carolina; Kazarain, Sergei G.; Alves, Marco A. V.; Blay, Alberto; Correa, Luciana; Zezell, Denise M.
2014-03-01
The cutting of bone is routinely required in medical procedures, especially in dental applications. In such cases, bone regeneration and new bone quality can determine the success of the treatment. This study investigated the main spectral differences of undamaged and healed bone using the ATR-FTIR spectroscopy technique. Three rabbits were submitted to a surgical procedure; a small piece of bone (3x3 mm2) was removed from both sides of their jaws using a high speed drill. After 15 days, the rabbits were euthanized and the jaws were removed. A bone slice was cut from each side of the jaw containing regions of undamaged and newly formed bone, resulting in six samples which were polished for spectroscopic comparison. The samples were analyzed by FTIR spectroscopy using a diamond ATR accessory. Spectral characteristics were compared and particular attention was paid to the proportion of phosphate to amide I bands and the width of the phosphate band. The results show that the ratio of phosphate to amide I is smaller in new bone tissue than in the undamaged bone, indicating a higher organic content in the newly formed bone. The analysis of the width of the phosphate band suggests a crystallinity difference between both tissues, since the width was higher in the new bone than in the natural bone. These results suggest that the differences observed in bone aging processes by FTIR spectroscopic can be applied to the study of healing processes.
Fourier transform infrared analysis of aerosol formed in the photooxidation of 1-octene
NASA Astrophysics Data System (ADS)
Palen, Edward J.; Allen, David T.; Pandis, Spyros N.; Paulson, Suzanne; Seinfeld, John H.; Flagan, Richard C.
The chemical composition of aerosol generated in the photooxidation of 1-octene was examined using infrared microscopy interfaced with a low pressure impactor. The low pressure impactor segregated the aerosol into eight size fractions and deposited the aerosol onto ZnSe impaction substrates. The ZnSe surfaces were transparent in the mid-infrared region and therefore allowed direct analysis of the aerosol, with no extraction, using infrared microscopy. Infrared spectra of the size segregated aerosol showed strong absorbances due to ketone, alcohol, carboxylic acid and organonitrate functional groups. Absorbance features were relatively independent of particle size, with the exception of the carboxylic acid absorbances, which were found only in the largest aerosol size fractions. Molar loadings for each of the groups were estimated, based on model compound calibration standards. The molar loadings indicate that most aerosol species are multifunctional, with an average of one ketone group per molecule, an alcohol group in two of every three molecules and an organonitrate group in one of every three molecules.
ERIC Educational Resources Information Center
Pezzolo, Alessandra De Lorenzi
2011-01-01
The diffuse reflectance infrared Fourier transform (DRIFT) spectra of sand samples exhibit features reflecting their composition. Basic multivariate analysis (MVA) can be used to effectively sort subsets of homogeneous specimens collected from nearby locations, as well as pointing out similarities in composition among sands of different origins.…
Mohanan, Sharika; Srivastava, Atul
2014-04-10
The present work is concerned with the development and application of a novel fringe analysis technique based on the principles of the windowed-Fourier-transform (WFT) for the determination of temperature and concentration fields from interferometric images for a range of heat and mass transfer applications. Based on the extent of the noise level associated with the experimental data, the technique has been coupled with two different phase unwrapping methods: the Itoh algorithm and the quality guided phase unwrapping technique for phase extraction. In order to generate the experimental data, a range of experiments have been carried out which include cooling of a vertical flat plate in free convection conditions, combustion of mono-propellant flames, and growth of organic as well as inorganic crystals from their aqueous solutions. The flat plate and combustion experiments are modeled as heat transfer applications wherein the interest is to determine the whole-field temperature distribution. Aqueous-solution-based crystal growth experiments are performed to simulate the mass transfer phenomena and the interest is to determine the two-dimensional solute concentration field around the growing crystal. A Mach-Zehnder interferometer has been employed to record the path-integrated quantity of interest (temperature and/or concentration) in the form of interferometric images in the experiments. The potential of the WFT method has also been demonstrated on numerically simulated phase data for varying noise levels, and the accuracy in phase extraction have been quantified in terms of the root mean square errors. Three levels of noise, i.e., 0%, 10%, and 20% have been considered. Results of the present study show that the WFT technique allows an accurate extraction of phase values that can subsequently be converted into two-dimensional temperature and/or concentration distribution fields. Moreover, since WFT is a local processing technique, speckle patterns and the inherent
Oinas, J; Rieppo, L; Finnilä, M A J; Valkealahti, M; Lehenkari, P; Saarakkala, S
2016-01-01
The changes in chemical composition of human articular cartilage (AC) caused by osteoarthritis (OA) were investigated using Fourier transform infrared microspectroscopy (FTIR-MS). We demonstrate the sensitivity of FTIR-MS for monitoring compositional changes that occur with OA progression. Twenty-eight AC samples from tibial plateaus were imaged with FTIR-MS. Hyperspectral images of all samples were combined for K-means clustering. Partial least squares regression (PLSR) analysis was used to compare the spectra with the OARSI grade (histopathological grading of OA). Furthermore, the amide I and the carbohydrate regions were used to estimate collagen and proteoglycan contents, respectively. Spectral peak at 1338 cm(-1) was used to estimate the integrity of the collagen network. The layered structure of AC was revealed using the carbohydrate region for clustering. Statistically significant correlation was observed between the OARSI grade and the collagen integrity in the superficial (r = -0.55) and the deep (r = -0.41) zones. Furthermore, PLSR models predicted the OARSI grade from the superficial (r = 0.94) and the deep (r = 0.77) regions of the AC with high accuracy. Obtained results suggest that quantitative and qualitative changes occur in the AC composition during OA progression, and these can be monitored by the use of FTIR-MS. PMID:27445254
Hu, Jun; Xiao, Rui; Shen, Dekui; Zhang, Huiyan
2013-01-01
Structural characteristics of benzene-ethanol-extracted lignin (BEL) and acetone-extracted lignin (AL) precipitated from black liquor were identified by elemental analysis, FTIR, (13)C NMR, and (1)H NMR, while the thermal behaviors were examined with thermogravimetric-Fourier transform infrared spectroscopy (TG-FTIR). The frequency of β-O-4 bonds per 100 C9 monomeric units was 28 and 17 for BEL and AL. Two-stage pyrolysis processes were observed for the two lignins. The mass loss rate of the initial solvent evolution stage (110-180 °C) of BEL was greater than that of AL. The two lignins presented slightly different mass loss curves and evolution profiles of gases in the main pyrolysis stage (280-500 °C). A global kinetic model was proposed for lignin pyrolysis and activation energies of 39.5 and 38.8 kJ/mol was obtained for BEL and AL. The results enhance understanding of lignin pyrolysis and facilitate commercial utilization of black-liquor lignin. PMID:23220109
Ross, Charles W; Simonsick, William J; Bogusky, Michael J; Celikay, Recep W; Guare, James P; Newton, Randall C
2016-01-01
Ceramides are a central unit of all sphingolipids which have been identified as sites of biological recognition on cellular membranes mediating cell growth and differentiation. Several glycosphingolipids have been isolated, displaying immunomodulatory and anti-tumor activities. These molecules have generated considerable interest as potential vaccine adjuvants in humans. Accurate analyses of these and related sphingosine analogues are important for the characterization of structure, biological function, and metabolism. We report the complementary use of direct laser desorption ionization (DLDI), sheath flow electrospray ionization (ESI) Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS) and high-field nuclear magnetic resonance (NMR) analysis for the rapid, accurate identification of hexacosanoylceramide and starting materials. DLDI does not require stringent sample preparation and yields representative ions. Sheath-flow ESI yields ions of the product and byproducts and was significantly better than monospray ESI due to improved compound solubility. Negative ion sheath flow ESI provided data of starting materials and products all in one acquisition as hexacosanoic acid does not ionize efficiently when ceramides are present. NMR provided characterization of these lipid molecules complementing the results obtained from MS analyses. NMR data was able to differentiate straight chain versus branched chain alkyl groups not easily obtained from mass spectrometry. PMID:27367671
Ross, Charles W.; Simonsick, William J.; Bogusky, Michael J.; Celikay, Recep W.; Guare, James P.; Newton, Randall C.
2016-01-01
Ceramides are a central unit of all sphingolipids which have been identified as sites of biological recognition on cellular membranes mediating cell growth and differentiation. Several glycosphingolipids have been isolated, displaying immunomodulatory and anti-tumor activities. These molecules have generated considerable interest as potential vaccine adjuvants in humans. Accurate analyses of these and related sphingosine analogues are important for the characterization of structure, biological function, and metabolism. We report the complementary use of direct laser desorption ionization (DLDI), sheath flow electrospray ionization (ESI) Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS) and high-field nuclear magnetic resonance (NMR) analysis for the rapid, accurate identification of hexacosanoylceramide and starting materials. DLDI does not require stringent sample preparation and yields representative ions. Sheath-flow ESI yields ions of the product and byproducts and was significantly better than monospray ESI due to improved compound solubility. Negative ion sheath flow ESI provided data of starting materials and products all in one acquisition as hexacosanoic acid does not ionize efficiently when ceramides are present. NMR provided characterization of these lipid molecules complementing the results obtained from MS analyses. NMR data was able to differentiate straight chain versus branched chain alkyl groups not easily obtained from mass spectrometry. PMID:27367671
NASA Astrophysics Data System (ADS)
Hendrickson, Christopher L.; Quinn, John P.; Kaiser, Nathan K.; Smith, Donald F.; Blakney, Greg T.; Chen, Tong; Marshall, Alan G.; Weisbrod, Chad R.; Beu, Steven C.
2015-09-01
We describe the design and initial performance of the first 21 tesla Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. The 21 tesla magnet is the highest field superconducting magnet ever used for FT-ICR and features high spatial homogeneity, high temporal stability, and negligible liquid helium consumption. The instrument includes a commercial dual linear quadrupole trap front end that features high sensitivity, precise control of trapped ion number, and collisional and electron transfer dissociation. A third linear quadrupole trap offers high ion capacity and ejection efficiency, and rf quadrupole ion injection optics deliver ions to a novel dynamically harmonized ICR cell. Mass resolving power of 150,000 ( m/Δm 50% ) is achieved for bovine serum albumin (66 kDa) for a 0.38 s detection period, and greater than 2,000,000 resolving power is achieved for a 12 s detection period. Externally calibrated broadband mass measurement accuracy is typically less than 150 ppb rms, with resolving power greater than 300,000 at m/z 400 for a 0.76 s detection period. Combined analysis of electron transfer and collisional dissociation spectra results in 68% sequence coverage for carbonic anhydrase. The instrument is part of the NSF High-Field FT-ICR User Facility and is available free of charge to qualified users.
Ruíz, A; Ayora Cañada, M J; Lendl, B
2001-02-01
The development of an automated, rapid and highly precise method for determination of the peroxide value in edible oils based on a continuous flow system and Fourier transform infrared (FTIR) spectroscopic detection is described. The sample stream was mixed with a solvent mixture consisting of 25% (v/v) toluene in hexanol which contained triphenylphosphine (TPP). The hydroperoxides present in the sample reacted stoichiometrically with TPP to give triphenylphosphine oxide (TPPO) which has a characteristic and intense absorption band at 542 cm-1. A 10% (m/v) TPP solution in the solvent mixture and a 100 cm reaction coil were necessary for complete reaction. FTIR transmission spectra were recorded using a flow cell equipped with CsI windows having an optical pathlength of 100 microns. By using tert-butyl hydroperoxide spiked oil standards and evaluation of the band formed at 542 cm-1 a linear calibration graph covering the range 1-100 PV (peroxide value; mequiv O2 kg-1 oil) was obtained. The relative standard deviation was 0.23% (n = 11) and the throughput 24 samples h-1. The developed system was also applied to the determination of PV in olive, sunflower and corn oils, showing good agreement with the official reference method of the European Community which is based on titration using organic solvents. The results obtained clearly show that the developed method is superior to the standard wet chemical method, hence suggesting its application in routine analysis and quality control. PMID:11235111
Hendrickson, Christopher L; Quinn, John P; Kaiser, Nathan K; Smith, Donald F; Blakney, Greg T; Chen, Tong; Marshall, Alan G; Weisbrod, Chad R; Beu, Steven C
2015-09-01
We describe the design and initial performance of the first 21 tesla Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. The 21 tesla magnet is the highest field superconducting magnet ever used for FT-ICR and features high spatial homogeneity, high temporal stability, and negligible liquid helium consumption. The instrument includes a commercial dual linear quadrupole trap front end that features high sensitivity, precise control of trapped ion number, and collisional and electron transfer dissociation. A third linear quadrupole trap offers high ion capacity and ejection efficiency, and rf quadrupole ion injection optics deliver ions to a novel dynamically harmonized ICR cell. Mass resolving power of 150,000 (m/Δm(50%)) is achieved for bovine serum albumin (66 kDa) for a 0.38 s detection period, and greater than 2,000,000 resolving power is achieved for a 12 s detection period. Externally calibrated broadband mass measurement accuracy is typically less than 150 ppb rms, with resolving power greater than 300,000 at m/z 400 for a 0.76 s detection period. Combined analysis of electron transfer and collisional dissociation spectra results in 68% sequence coverage for carbonic anhydrase. The instrument is part of the NSF High-Field FT-ICR User Facility and is available free of charge to qualified users. PMID:26091892
Stockdale, Gregory; Murphy, Brian M; D'Antonio, Jennifer; Manning, Mark Cornell; Al-Azzam, Wasfi
2015-01-01
Comparing higher order structure (HOS) in therapeutic proteins is a significant challenge. Previously, we showed that changes in solution conditions produced detectable changes in the second-derivative amide I Fourier transform infrared (FTIR) spectra for a variety of model proteins. Those comparisons utilized vector-based approaches, such as spectral overlap and spectral correlation coefficients to quantify differences between spectra. In this study, chemometric analyses of the same data were performed, to classify samples into different groups based on the solution conditions received. The solution conditions were composed of various combinations of temperature, pH, and salt types. At first, principal component analysis (PCA) was used to visually demonstrate that FTIR spectra respond to changes in solution conditions, which, presumably indicates variations in HOS. This observed when samples from the same solution condition form clusters within a PCA score plot. The second approach, called soft independent modeling of class analogy (SIMCA), was conducted to account for the within-class experimental error for the lysozyme spectra. The DModX values, indicative of the distance of each spectra to their respective class models, was found to be a more sensitive quantitative indicator of changes in HOS, when compared with the modified area of overlap algorithm. The SIMCA approach provides a metric to determine whether new observations do, or do not belong to a particular class or group. Thus, SIMCA is the recommended approach when multiple samples from each condition are available. PMID:25382804
Pounder, F Nell; Reddy, Rohith K; Bhargava, Rohit
2016-06-23
Breast cancer screening provides sensitive tumor identification, but low specificity implies that a vast majority of biopsies are not ultimately diagnosed as cancer. Automated techniques to evaluate biopsies can prevent errors, reduce pathologist workload and provide objective analysis. Fourier transform infrared (FT-IR) spectroscopic imaging provides both molecular signatures and spatial information that may be applicable for pathology. Here, we utilize both the spectral and spatial information to develop a combined classifier that provides rapid tissue assessment. First, we evaluated the potential of IR imaging to provide a diagnosis using spectral data alone. While highly accurate histologic [epithelium, stroma] recognition could be achieved, the same was not possible for disease [cancer, no-cancer] due to the diversity of spectral signals. Hence, we employed spatial data, developing and evaluating increasingly complex models, to detect cancers. Sub-mm tumors could be very confidently predicted as indicated by the quantitative measurement of accuracy via receiver operating characteristic (ROC) curve analyses. The developed protocol was validated with a small set and statistical performance used to develop a model that predicts study design for a large scale, definitive validation. The results of evaluation on different instruments, at higher noise levels, under a coarser spectral resolution and two sampling modes [transmission and transflection], indicate that the protocol is highly accurate under a variety of conditions. The study paves the way to validating IR imaging for rapid breast tumor detection, its statistical validation and potential directions for optimization of the speed and sampling for clinical deployment. PMID:27095431
Phalen, R N; Que Hee, Shane S
2005-06-01
This study developed a method to produce uniform captan surface films on a disposable nitrile glove for quantitation with a portable attenuated total reflection Fourier transform infrared (ATR-FTIR) spectrometer. A permeation test was performed using aqueous captan formulation. Uniform captan surface films were produced using solvent casting with 2-propanol and a 25 mm filter holder connected to a vacuum manifold to control solvent evaporation. The coefficient of variation of the reflectance at 1735 +/- 5 cm(-1) was minimized by selection of the optimum solvent volume, airflow rate, and evaporation time. At room temperature, the lower to upper quantifiable limits were 0.31-20.7 microg/cm2 (r = 0.9967; p < or = 0.05) for the outer glove surface and 0.55-17.5 microg/cm2 (r = 0.9409; p < or = 0.05) for the inner surface. Relative humidity and temperature did not affect the uncoated gloves at the wavelength of captan analysis. Glove screening using ATR-FTIR was necessary as a control for between-glove variation. Captan permeation, after 8 hours exposure to an aqueous concentration of 217 mg/mL of Captan 50-WP, was detected at 0.8 +/- 0.3 microg/cm2 on the inner glove surface. ATR-FTIR can detect captan permeation and can determine the protectiveness of this glove in the field. PMID:16053538
Oinas, J.; Rieppo, L.; Finnilä, M. A. J.; Valkealahti, M.; Lehenkari, P.; Saarakkala, S.
2016-01-01
The changes in chemical composition of human articular cartilage (AC) caused by osteoarthritis (OA) were investigated using Fourier transform infrared microspectroscopy (FTIR-MS). We demonstrate the sensitivity of FTIR-MS for monitoring compositional changes that occur with OA progression. Twenty-eight AC samples from tibial plateaus were imaged with FTIR-MS. Hyperspectral images of all samples were combined for K-means clustering. Partial least squares regression (PLSR) analysis was used to compare the spectra with the OARSI grade (histopathological grading of OA). Furthermore, the amide I and the carbohydrate regions were used to estimate collagen and proteoglycan contents, respectively. Spectral peak at 1338 cm−1 was used to estimate the integrity of the collagen network. The layered structure of AC was revealed using the carbohydrate region for clustering. Statistically significant correlation was observed between the OARSI grade and the collagen integrity in the superficial (r = −0.55) and the deep (r = −0.41) zones. Furthermore, PLSR models predicted the OARSI grade from the superficial (r = 0.94) and the deep (r = 0.77) regions of the AC with high accuracy. Obtained results suggest that quantitative and qualitative changes occur in the AC composition during OA progression, and these can be monitored by the use of FTIR-MS. PMID:27445254