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1

Fast quantum Fourier-Weyl-Heisenberg transforms  

Microsoft Academic Search

We study the Fourier harmonic analysis of a functions on discrete 1D and nD Heisenberg-Weyl groups HW3 and HW2n+1, where K equals GF(2), GF(2m), GF(p), GF(pm) are the Galois fields, and develop fast quantum Fourier- Heisenberg-Weyl transforms on this groups.

Valeri G. Labunets; Ekaterina V. Rundblad-Labunets; Jaakko T. Astola

2001-01-01

2

Semiclassical Fourier Transform for Quantum Computation  

Microsoft Academic Search

It is shown that the Fourier transform preceding the final measurement in Shor's algorithm for factorization on a quantum computer can be carried out in a semiclassical way by using the ``classical'' (macroscopic) signal resulting from measuring one bit to determine the type of measurement carried out on the next bit, and so forth. In this way all the two-bit

Robert B. Griffiths; Chi-Sheng Niu

1996-01-01

3

Fourier-transform quantum state tomography  

NASA Astrophysics Data System (ADS)

We propose a technique for performing quantum state tomography of photonic polarization-encoded multiqubit states. Our method uses a single rotating wave plate, a polarizing beam splitter, and two photon-counting detectors per photon mode. As the wave plate rotates, the photon counters measure a pseudocontinuous signal which is then Fourier transformed. The density matrix of the state is reconstructed using the relationship between the Fourier coefficients of the signal and the Stokes’ parameters that represent the state. The experimental complexity, i.e., different wave plate rotation frequencies, scales linearly with the number of qubits.

Mohammadi, Mohammadreza; Bra?czyk, Agata M.; James, Daniel F. V.

2013-01-01

4

Fourier transform identities in quantum mechanics and the quantum line  

NASA Astrophysics Data System (ADS)

We give a quantum-mechanical interpretation of some modular identities (LF)3=?L2 arising in conformal field theory and the theory of quantum groups in relation to the mapping class group of a torus. The interpretation follows by evaluating the identity in the case of a non-standard group of the real line. The operation L takes the form of the Fourier transform of wave functions in L2(R) with length scale ???/m. We find that this can be factorised as ?L=exp(-i?p2/2m?) exp(-ix2/2??) P exp(-i?p2/2m?), where x, p mare the usual quantum mechanical position and momentum operators, P is the parity and ?=(1-i)/?2 is a normalization constant determined by verifying the identity on wavepackets. We understand this further in terms of the observation that the Fourier transformation is realized on the wavefunctions in quantum mechanics as the evolution by a quantum harmonic oscillator of period 2?? for 1/4 of a cycle. SERC Advanced Fellow and Drapers Fellow of Pembroke College, Cambridge.

Lyubashenko, V. V.; Majid, S.

1992-06-01

5

Quantum computation of Fourier transforms over symmetric groups  

Microsoft Academic Search

Many algorithmic developments in quantum com- plexity theory, including Shor's celebrated algorithms for factoring and discrete logs, have made use of Fourier transforms over abelian groups. That is, at some point in the computation, the macline is in a superposition of states corresponding to elements of a finite abelian group G, and in quantum polynomial time (i.e., poly- nomial in

Robert Beals

1997-01-01

6

Efficient quantum circuit for implementing discrete quantum Fourier transform in solid-state qubits  

NASA Astrophysics Data System (ADS)

Based on the iSWAP gate generated from the XY interaction between solid-state qubits, we present an efficient quantum circuit for the implementation of discrete quantum Fourier transform. The relatively cumbersome and expensive controlled-Rk gate and SWAP gate operations required for implementing discrete quantum Fourier transform in the naive quantum circuit are replaced only by iSWAP gate operation. The scheme can be realized using any physical system with XY interaction and it would be a useful step towards the implementation of more complex quantum computation in solid-state qubits.

Wang, Hong-Fu; Jiang, Xin-Xin; Zhang, Shou; Yeon, Kyu-Hwang

2011-06-01

7

Simple implementation of discrete quantum Fourier transform via cavity quantum electrodynamics  

NASA Astrophysics Data System (ADS)

We propose a scheme for implementing discrete quantum Fourier transform in cavity quantum electrodynamics (QED). The experimental implementation is appealingly simple because the combined effect of the complex controlled-Rk gate and SWAP gate operations required for implementing discrete quantum Fourier transform in the naive quantum circuit is replaced by the one-step CRkS gate, which can be directly implemented via atom-cavity interaction with the assistance of classical fields. We propose the detailed experimental procedure and analyze the experimental feasibility. The experimental implementation of the scheme would show the full power of quantum algorithm and would open wide prospects for more complicated quantum computation with atoms in QED.

Wang, Hong-Fu; Zhu, Ai-Dong; Zhang, Shou; Yeon, Kyu-Hwang

2011-01-01

8

Entanglement of periodic states, the quantum Fourier transform, and Shor's factoring algorithm  

SciTech Connect

The preprocessing stage of Shor's algorithm generates a class of quantum states referred to as periodic states, on which the quantum Fourier transform is applied. Such states also play an important role in other quantum algorithms that rely on the quantum Fourier transform. Since entanglement is believed to be a necessary resource for quantum computational speedup, we analyze the entanglement of periodic states and the way it is affected by the quantum Fourier transform. To this end, we derive a formula that evaluates the Groverian entanglement measure for periodic states. Using this formula, we explain the surprising result that the Groverian entanglement of the periodic states built up during the preprocessing stage is only slightly affected by the quantum Fourier transform.

Most, Yonatan; Biham, Ofer [Racah Institute of Physics, Hebrew University, Jerusalem IL-91904 (Israel); Shimoni, Yishai [Racah Institute of Physics, Hebrew University, Jerusalem IL-91904 (Israel); Department of Neurology, Mount Sinai School of Medicine, New York, New York (United States)

2010-05-15

9

Fast quantum nD Fourier and radon transforms  

Microsoft Academic Search

Fast Classical and quantum algorithms are introduced for a wide class of non-separable nD discrete unitary K- transforms(DKT)KNn. They require a number of 1D DKT Kn smaller than in the Cooley-Tukey radix-p FFT-type approach. The method utilizes a decomposition of the nDK- transform into a product of original nD discrete Radon Transform and of a family parallel\\/independ 1DK-transforms. If the

Valeri G. Labunets; Ekaterina V. Rundblad-Labunets; Jaakko T. Astola

2001-01-01

10

Analysis of electronic structures of quantum dots using meshless Fourier transform k.p method  

Microsoft Academic Search

We develop a complete Fourier transform k.p method and present its application for a theoretical investigation on electronic structures of quantum dots with consideration of the built-in strain effects. The Fourier transform technique is applied to the periodic position-dependent Hamiltonian, and a simple and neat expression of the Hamiltonian matrix in the Fourier domain is formulated due to the orthogonality

Qiuji Zhao; Ting Mei

2011-01-01

11

Analysis of electronic structures of quantum dots using meshless Fourier transform k.p method  

NASA Astrophysics Data System (ADS)

We develop a complete Fourier transform k.p method and present its application for a theoretical investigation on electronic structures of quantum dots with consideration of the built-in strain effects. The Fourier transform technique is applied to the periodic position-dependent Hamiltonian, and a simple and neat expression of the Hamiltonian matrix in the Fourier domain is formulated due to the orthogonality of exponential functions. Spurious solutions can be avoided due to the truncation of high Fourier frequencies. A kinetic Hamiltonian matrix in momentum domain is formulated by entering the analytical Fourier transform of the quantum-dot shape function into the neat Hamiltonian matrix easily, which allows meshless numerical implementation. The formulation of strain Hamiltonian matrix is done by convolution of Fourier series of strain components and Fourier series of the quantum-dot shape functions. Therefore, an original Fourier transform-based k.p approach is developed by combining the kinetic Hamiltonian matrix and the strain Hamiltonian. This approach is adopted to study the dimension effect and strain effect on the ground states of electrons and holes of pyramidal quantum dots that are truncated to different heights. The ground-state energy variation shows that the electron state is the most sensitive to these effects and the strain effect on E1, LH1, and HH1 is more prominent for sharperquantum dots. This investigation shows that band mixing between the conduction band and valence band, and band mixing between heavy-hole and light-hole bands are reduced due to the strain effect, whereas this effect is more prominent for nontruncated pyramidal quantum dots due to the stress concentration. Among the three ground states, light-hole states are more weakly confined in the nonpyramidal quantum dot and shift to the tip of the pyramid due to the strain.

Zhao, Qiuji; Mei, Ting

2011-03-01

12

Novel image encryption/decryption based on quantum Fourier transform and double phase encoding  

NASA Astrophysics Data System (ADS)

A novel gray-level image encryption/decryption scheme is proposed, which is based on quantum Fourier transform and double random-phase encoding technique. The biggest contribution of our work lies in that it is the first time that the double random-phase encoding technique is generalized to quantum scenarios. As the encryption keys, two phase coding operations are applied in the quantum image spatial domain and the Fourier transform domain respectively. Only applying the correct keys, the original image can be retrieved successfully. Because all operations in quantum computation must be invertible, decryption is the inverse of the encryption process. A detailed theoretical analysis is given to clarify its robustness, computational complexity and advantages over its classical counterparts. It paves the way for introducing more optical information processing techniques into quantum scenarios.

Yang, Yu-Guang; Xia, Juan; Jia, Xin; Zhang, Hua

2013-07-01

13

A multiparty quantum proxy group signature scheme for the entangled-state message with quantum Fourier transform  

Microsoft Academic Search

A novel multiparty quantum proxy group signature scheme is proposed based on the discrete quantum Fourier transform in order\\u000a to improve the efficiency and the security of quantum signature for an n-dimensional quantum message, in which the generation and verification of the signature can be successfully conducted only\\u000a if all the n participants cooperate with each other and with the

Jinjing Shi; Ronghua Shi; Ying Tang; Moon Ho Lee

2011-01-01

14

Global phase and minimum time of quantum Fourier transform for qudits represented by quadrupole nuclei  

NASA Astrophysics Data System (ADS)

We demonstrate the relation between a global phase of the quantum gate and the layout of energy levels of its effective Hamiltonian required for implementing the gate for minimum time. By an example of the quantum Fourier transform gate for a qudit represented by a quadrupole nucleus with the spin I = 1, the effective Hamiltonians and minimum implementation times for different global phases are found. Using numerical optimal control methods, the problem of the global phase in searching for the optimal pulse shape is considered in detail for the quantum Fourier transform gate at I = 1, 3/2, 2, and 5/2. It is shown that at the constrained control time the gradient algorithms can converge to the solutions corresponding to different global phases or the same global phase with different minimum times of the gate implementation.

Shauro, V. P.; Zobov, V. E.

2013-10-01

15

Quantum multiresolution analysis via fast Fourier transform on Heisenberg group  

Microsoft Academic Search

We study classical and quantum harmonic analysis of phase space functions (classical observes) on finite Heisenberg group HW2N+1(ZNmn, ZNmn, Zmn) over the ring Zmn. This group is the discrete version of the real Heisenberg group HW2N+1(RN, RN, R), where R is the real field. These functions have one dimensional and m1, m2,...,mn-dimensions matrix valued spectral components (for irreducible representations of

Ekaterina Rundblad; Valeriy G. Labunets; Peter Novak

2005-01-01

16

Efficient quantum-state tomography for quantum-information processing using a two-dimensional Fourier-transform technique  

SciTech Connect

A method of quantum-state tomography for quantum-information processing is described. The method is based on the use of the Fourier-transform technique and involves detection of all the diagonal elements of the density matrix in a one-dimensional experiment and all the off-diagonal elements by a two-dimensional experiment. The method is efficient for a large number of qubits ({>=}5). The proposed method is outlined using a two-qubit system and demonstrated using simulations by tomographing arbitrary complex density matrices of two- and four-qubit systems.

Das, Ranabir; Mahesh, T.S. [Department of Physics, Indian Institute of Science, Bangalore 560012 (India); Kumar, Anil [Department of Physics, Indian Institute of Science, Bangalore 560012, (India); Sophisticated Instruments Facility, Indian Institute of Science, Bangalore 560012 (India)

2003-06-01

17

Scaling laws for Shor's algorithm with a banded quantum Fourier transform  

NASA Astrophysics Data System (ADS)

We investigate the performance of a streamlined version of Shor's algorithm in which the quantum Fourier transform is replaced by a banded version that, for each qubit, retains only coupling to its b nearest neighbors. Defining the performance P(n,b) of the n-qubit algorithm for bandwidth b as the ratio of the success rates of Shor's algorithm equipped with the banded and the full-bandwidth (b=n-1) versions of the quantum Fourier transform, our numerical simulations show that P(n,b)?exp[-?max2(n,b)/100] for nnt(b) (exponential regime), where nt(b), the location of the transition, is approximately given by nt(b)?b+5.9+7.7(b+2)-47 for b?8, ?max(n,b)=2?[2-b-1(n-b-2)+2-n], and ?b?1.1×2-2b. Analytically we obtain P(n,b)?exp[-?max2(n,b)/64] for nnt(b), where ?b(a)?(?2)/(12ln(2))×2-2b?1.19×2-2b. Thus, our analytical results predict the ?max2 scaling (nnt) of the data perfectly. In addition, in the large-n regime, the prefactor in ?b(a) is close to the results of our numerical simulations, and in the low-n regime, the numerical scaling factor in our analytical result is within a factor 2 of its numerical value. As an example we show that b=8 is sufficient for factoring RSA-2048 with a 95% success rate.

Nam, Y. S.; Blümel, R.

2013-03-01

18

Fourier Transform Mass Spectrometry  

PubMed Central

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.

Scigelova, Michaela; Hornshaw, Martin; Giannakopulos, Anastassios; Makarov, Alexander

2011-01-01

19

Super fast Fourier transform  

NASA Astrophysics Data System (ADS)

In this paper, we have developed the recursive fast orthogonal mapping algorithms based fast Fourier transforms. Particularly, we introduced a new fast Fourier transform algorithm with linear multiplicative complexity. The proposed algorithms not only reduces the multiplicative complexity, but also is comparable to the existing methods such as Duhamel, Heideman, Burrus, Vetterli, Wang [11,15,16,19,21,27,28] in the total number of operations (arithmetic complexity, or the number of multiplications and additions).

Agaian, Sos S.; Caglayan, Okan

2006-02-01

20

Fourier Transform I  

NSDL National Science Digital Library

Created by Lang Moore for the Connected Curriculum Project, the purpose of this module is to study the Fourier transform and use it to describe solutions of the heat equation on an infinite rod. This is one of a much larger set of learning modules hosted by Duke University.

Moore, Lang

2010-07-02

21

Dispersive Fourier transform spectroscopy  

Microsoft Academic Search

Dispersive Fourier transform spectroscopy (DFTS) is a technique for determining the optical constants of solids, liquids and gases from direct measurements of both the amplitude and phase of either their reyection or transmission coeficients. Measurements are usually made at normal incidence with the specimen in one arm of a Michelson interferometer. The technique has been widely used for measurements in

T. J. Parker

1990-01-01

22

Fourier transform of supermeasures  

NASA Astrophysics Data System (ADS)

In the note, a Smolyanov-Shavgulidze model of infinite-dimensional superspace H ? = ?0 hat ? H 0 ? ?1 hat ? H 1 corresponding to a Hilbert space H = H 0 ? H 1 over a Hilbert superalgebra ? = ?0 ? ?1 is considered. Its relation to the Khrennikov superspace is discussed. Moreover, H ? is equipped with the structure of Hilbert superspace with an inner superproduct (·, ·)?. The supermeasures are defined as ?? hat ? (? H 1)-valued measures on H 0 (?? stands for the complexification of ?). The definition of the Fourier supertransform is similar to the ordinary one, tilde ? ( y) = int _{H_? } e^{i(y, z)_? } ?( dz). It turns out that the values of the Fourier supertransform of a supermeasure on the subspace overline H _? = H 0 ? ?1 hat ? H 1 can be obtained by applying a certain operator to the values of the classical Fourier transform. The main result is the theorem claiming that the Fourier supertransform of supermeasures is isometric on superspaces with zero even part ( H 0 = {0}). As a corollary, we note that the operator of Fourier supertransform is injective. We also give necessary and sufficient conditions for the countable additivity of cylindrical supermeasures in terms of continuity of their Fourier supertransforms (an analog of the Minlos-Sazonov theorem).

Panyunin, N. M.

2007-12-01

23

Rainbow Fourier transform  

NASA Astrophysics Data System (ADS)

We present a novel technique for remote sensing of cloud droplet size distributions. Polarized reflectances in the scattering angle range between 135° and 165° exhibit a sharply defined rainbow structure, the shape of which is determined mostly by single scattering properties of cloud particles, and therefore, can be modeled using the Mie theory. Fitting the observed rainbow with such a model (computed for a parameterized family of particle size distributions) has been used for cloud droplet size retrievals. We discovered that the relationship between the rainbow structures and the corresponding particle size distributions is deeper than it had been commonly understood. In fact, the Mie theory-derived polarized reflectance as a function of reduced scattering angle (in the rainbow angular range) and the (monodisperse) particle radius appears to be a proxy to a kernel of an integral transform (similar to the sine Fourier transform on the positive semi-axis). This approach, called the rainbow Fourier transform (RFT), allows us to accurately retrieve the shape of the droplet size distribution by the application of the corresponding inverse transform to the observed polarized rainbow. While the basis functions of the proxy-transform are not exactly orthogonal in the finite angular range, this procedure needs to be complemented by a simple regression technique, which removes the retrieval artifacts. This non-parametric approach does not require any a priori knowledge of the droplet size distribution functional shape and is computationally fast (no look-up tables, no fitting, computations are the same as for the forward modeling).

Alexandrov, Mikhail D.; Cairns, Brian; Mishchenko, Michael I.

2012-12-01

24

Representation of the quantum Fourier transform on multilevel basic elements by a sequence of selective rotation operators  

NASA Astrophysics Data System (ADS)

To experimentally realize quantum computations on d-level basic elements (qudits) at d > 2, it is necessary to develop schemes for the technical realization of elementary logical operators. We have found sequences of selective rotation operators that represent the operators of the quantum Fourier transform (Walsh-Hadamard matrices) for d = 3-10. For the prime numbers 3, 5, and 7, the well-known method of linear algebra is applied, whereas, for the factorable numbers 6, 9, and 10, the representation of virtual spins is used (which we previously applied for d = 4, 8). Selective rotations can be realized, for example, by means of pulses of an RF magnetic field for systems of quadrupole nuclei or laser pulses for atoms and ions in traps.

Ermilov, A. S.; Zobov, V. E.

2007-12-01

25

Application of the fast Fourier transform to computation of Fourier integrals, Fourier series, and convolution integrals  

Microsoft Academic Search

The fast Fourier transform is a computational procedure for calculating the finite Fourier transform of a time series. In this paper, the properties of the finite Fourier transform are related to commonly used integral transforms including the Fourier transform and convolution integrals. The relationship between the finite Fourier transform and Fourier series is also discussed.

J. Cooley; P. Lewis; P. Welch

1967-01-01

26

A Quick Fourier Transform Algorithm.  

National Technical Information Service (NTIS)

A new highly efficient algorithm for calculation of Fourier coefficients on a digital computer is presented. For sample sizes up to 1024 points, this algorithm is competitive with the Fast Fourier Transform. For example, on a 5-microsec cycle time machine...

J. F. Kohne

1970-01-01

27

Optical Fourier transform techniques for advanced Fourier spectroscopy systems.  

PubMed

A review of multichannel long integration time, optical Fourier transform techniques for advanced Fourier spectroscopy systems is followed by the description of a new multichannel time-integrating optical Fourier transform chirp-Z system and a discussion of its use in Fourier spectroscopy signal processing. PMID:20221177

Casasent, D; Psaltis, D

1980-06-15

28

The Fourier Transform  

Microsoft Academic Search

To calculate a transform, just listen. The ear automatically performs the calculation, which the intellect can execute only after years of mathematical education. The ear formulates a transform by converting sound-the waves of pressure traveling through time and the atmosphere-into a spectrum, a description of the sound as a series of volumes at distinct pitches. The brain turns this information

Ronald N. Bracewell

1989-01-01

29

Analysis of thermal band gap variations of PbS quantum dots by Fourier transform transmission and emission spectroscopy  

NASA Astrophysics Data System (ADS)

Fourier transmission and emission spectroscopy was employed in the range from 5 to 300 K to measure the thermal band gap shift of 4.7 nm PbS quantum dots. The analytical comparison of fits carried out with the expressions of Varshni and Fan revealed limited accuracy of the Varshni fitting parameters. Evidence is presented that transmission spectroscopy in conjunction with the Fan model concurs with the microscopic material features, resulting in a tool to determine intrinsic properties of quantum dots.

Ullrich, B.; Wang, J. S.; Brown, G. J.

2011-08-01

30

Room Temperature Observation of the Energy Levels of Mid-Infrared Quantum Well Lasers using Fourier Transform Infrared-Surface Photovoltage Spectroscopy  

Microsoft Academic Search

At room temperature, we demonstrate an unambiguous detection of the ground- and excited-state transitions of mid-infrared GaInSb\\/AlGaInSb type I quantum well (QW) lasers grown on GaAs using a new technique based on Fourier transform infrared surface photovoltage spectroscopy. It is found that none of the currently established spectroscopic techniques is able to detect even the ground state transition of these

Tarun Kumar Sharma; Natasha Elizabeth Fox; Thomas Jeff Cockburn Hosea; Geoffrey Richard Nash; Stuart David Coomber; Louise Buckle; Martin Trevor Emeny; Tim Ashley

2008-01-01

31

A Fast Fourier Transform Compiler  

Microsoft Academic Search

The FFTW library for computing the discrete Fourier transform (DFT) has gained a wide acceptance in both academia and industry, because it provides excellent performance on a variety of machines (even competitive with or faster than equivalent libraries supplied by vendors). In FFTW, most of the performance-critical code was generated automatically by a special-purpose compiler, called genfft, that outputs C

Matteo Frigo

1999-01-01

32

Fourier transform spectroscopy in astrophysics  

NASA Astrophysics Data System (ADS)

A review of studies using Fourier transform spectroscopy is presented. Topics include the use of this technique in solar system spectroscopy, including the sun, planets, and comets. Measurements of the molecular hydrogen emission from shock waves in molecular clouds, the study of embedded sources in molecular clouds, and IR spectroscopy of young stars are examined. The use of Fourier spectroscopy in studying the abundances of C2, CH, CN, CO, CS, H2, and OH, the determination of radial velocities, atmospheric structure and motions, the study of circumstellar material, and laboratory spectroscpoy are also discussed.

Ridgway, Stephen T.

33

Fast classical and quantum fractional Walsh transforms  

Microsoft Academic Search

The fractional Fourier transform (FRFT) is one-parametric generalization of the classical Fourier transform. FRFT was introduced in the 1980s and found a lot of applications in signal processing. The time and spectral domains are both special cases of the fractional Fourier domain. They correspond to the Oth and 1st functional Fourier domains, respectively. We introduce the classical and quantum fractional

Valeri Labunets; Ekaterina Labunets-Rundblad; Karen Egiazarian; Jaakko Astola

2001-01-01

34

A Short Biography of Joseph Fourier and Historical Development of Fourier Series and Fourier Transforms  

ERIC Educational Resources Information Center

|This article deals with a brief biographical sketch of Joseph Fourier, his first celebrated work on analytical theory of heat, his first great discovery of Fourier series and Fourier transforms. Included is a historical development of Fourier series and Fourier transforms with their properties, importance and applications. Special emphasis is…

Debnath, Lokenath

2012-01-01

35

AIR POLLUTION MEASUREMENT BY FOURIER TRANSFORM SPECTROSCOPY  

EPA Science Inventory

Fourier transform spectroscopy substantially reduces the limitations on infrared methods of pollution measurement. EPA has used long path cells and Fourier transform spectrometers for pollutant measurement both in the laboratory and in the field. Labile pollutants are best measur...

36

Remarks on the Fast Fourier Transform.  

National Technical Information Service (NTIS)

The author discusses the fast Fourier transform and other waveform processing algorithms, emphasizing that because it is especially useful in attacking large problems, simpler solutions may be missed if the fast Fourier transform is used as a likely avenu...

C. M. Rader

1969-01-01

37

What is the fast Fourier transform?  

Microsoft Academic Search

The fast Fourier transform is a computational tool which facilitates signal analysis such as power spectrum analysis and filter simulation by means of digital computers. It is a method for efficiently computing the discrete Fourier transform of a series of data samples (referred to as a time series). In this paper, the discrete Fourier transform of a time series is

W. T. Cochran; J. W. Cooley; D. L. Favin; H. D. Helms; R. A. Kaenel; W. W. Lang; D. E. Nelson; C. M. Rader; P. D. Welch

1967-01-01

38

An introduction to the angular Fourier transform  

Microsoft Academic Search

The author introduces the angular Fourier transform (AFT), a generalization of the classical Fourier transform. The AFT can be interpreted as a rotation on the time-frequency plane. An AFT with an angle of alpha = pi \\/2 corresponds to the classical Fourier transform, and an AFT with alpha =0 corresponds to the identity operator. The angles of successively performed AFTs

Luis B. Almeida; R. Alves Redol

1993-01-01

39

Fourier-transform laser spectroscopy  

NASA Astrophysics Data System (ADS)

The development of microphotonic sensors based on Fourier-transform laser spectroscopy (FT-LS) is discussed. The application demonstrated is for measurement of vapors from the hydrocarbon fuels JP-8, diesel fuel, and gasoline. The two-laser prototype FT-LS sensor used for our research employs distributed-feedback lasers in the near-infrared spectral region (1.3- and 1.7-?m wavelength). An extension of this research to multilaser arrays is discussed. We believe that this is the first measurement of middle-distillate fuel-vapor concentrations using this optical mixing technique.

McNesby, Kevin L.; Miziolek, Andrzej W.

2003-04-01

40

Laser Field Imaging Through Fourier Transform Heterodyne  

SciTech Connect

The authors present a detection process capable of directly imaging the transverse amplitude, phase, and Doppler shift of coherent electromagnetic fields. Based on coherent detection principles governing conventional heterodyned RADAR/LADAR systems, Fourier Transform Heterodyne incorporates transverse spatial encoding of the reference local oscillator for image capture. Appropriate selection of spatial encoding functions allows image retrieval by way of classic Fourier manipulations. Of practical interest: (1) imaging may be accomplished with a single element detector/sensor requiring no additional scanning or moving components, (2) as detection is governed by heterodyne principles, near quantum limited performance is achievable, (3) a wide variety of appropriate spatial encoding functions exist that may be adaptively configured in real-time for applications requiring optimal detection, and (4) the concept is general with the applicable electromagnetic spectrum encompassing the RF through optical.

Cooke, B.J.; Laubscher, B.E.; Olivas, N.L.; Galbraith, A.E.; Strauss, C.E.; Grubler, A.C.

1999-04-05

41

Quantum transformations  

SciTech Connect

We show that the quantum Hamilton-Jacobi equation can be written in the classical form with the spatial derivative {partial_derivative}{sub q} replaced by {partial_derivative}{sub q} with dq = dq/{radical}1{minus}{beta}{sup 2}(q), where {beta}{sup 2}(q) is strictly related to the quantum potential. This can be seen as the opposite of the problem of finding the wave function representation of classical mechanics as formulated by Schiller and Rosen. The structure of the above {open_quotes}quantum transformation{close_quotes}, related to the recently formulated equivalence principle, indicates that the potential deforms space geometry. In particular, a result by Flanders implies that both W(q) = V(q) {minus} E and the quantum potential Q are proportional to the curvatures {kappa}{sub W} and {kappa}{sub Q} which arise as natural invariants in an equivalence problem for curves in the projective line. In this formulation the Schroedinger equation takes the geometrical form ({partial_derivative}{sub q}{sup 2} + {kappa}{sub W}){psi} = 0.

Faraggi, A.E. [Univ. of Florida, Gainesville, FL (United States). Institute for Fundamental Theory; Matone, M. [Univ. of Padova (Italy). Dept. of Physics G. Galilei

1998-01-09

42

Dual Comb Fourier Transform Spectroscopy  

NASA Astrophysics Data System (ADS)

The advent of laser frequency combs a decade ago has already revolutionized optical frequency metrology and precision spectroscopy. Extensions of laser combs from the THz region to the extreme ultraviolet and soft x-ray frequencies are now under exploration. Such laser combs have become enabling tools for a growing tree of applications, from optical atomic clocks to attosecond science. Recently, the millions of precisely controlled laser comb lines that can be produced with a train of ultrashort laser pulses have been harnessed for highly multiplexed molecular spectroscopy. Fourier multi-heterodyne spectroscopy, dual comb spectroscopy, or asynchronous optical sampling spectroscopy with frequency combs are emerging as powerful new spectroscopic tools. Even the first proof-of-principle experiments have demonstrated a very exciting potential for ultra-rapid and ultra-sensitive recording of complex molecular spectra. Compared to conventional Fourier transform spectroscopy, recording times could be shortened from seconds to microseconds, with intriguing prospects for spectroscopy of short lived transient species. Longer recording times allow high resolution spectroscopy of molecules with extreme precision, since the absolute frequency of each laser comb line can be known with the accuracy of an atomic clock. The spectral structure of sharp lines of a laser comb can be very useful even in the recording of broadband spectra without sharp features, as they are e.g. encountered for molecular gases or in the liquid phase. A second frequency comb of different line spacing permits the generation of a comb of radio frequency beat notes, which effectively map the optical spectrum into the radio frequency regime, so that it can be recorded with a single fast photodetector, followed by digital signal analysis. In the time domain, a pulse train of a mode-locked femtosecond laser excites some molecular medium at regular time intervals. A second pulse train of different repetition frequency interferometrically samples the transient response or "free induction decay" of the medium, akin to an optical sampling oscilloscope.

Hänsch, T. W.; Picqué, N.

2010-06-01

43

Physically constrained Fourier transform deconvolution method.  

PubMed

An iterative Fourier-transform-based deconvolution method for resolution enhancement is presented. This method makes use of the a priori information that the data are real and positive. The method is robust in the presence of noise and is efficient especially for large data sets, since the fast Fourier transform can be employed. PMID:19412237

Flaherty, Francis A

2009-05-01

44

Lagrange-mesh calculations and Fourier transform  

SciTech Connect

The Lagrange-mesh method is a very accurate procedure for computing eigenvalues and eigenfunctions of a two-body quantum equation written in the configuration space. Using a Gauss quadrature rule, the method only requires the evaluation of the potential at some mesh points. The eigenfunctions are expanded in terms of regularized Lagrange functions, which vanish at all mesh points except one. Using the peculiarities of the method, it is shown that the Fourier transform of the eigenfunctions, computed in the configuration space, can easily be obtained with good accuracy in the physical domain of the momentum space. Also, observables in this space can easily be computed with good accuracy only using matrix elements and eigenfunctions computed in the configuration space.

Lacroix, Gwendolyn; Semay, Claude [Service de Physique Nucleaire et Subnucleaire, Universite de Mons-UMONS, Academie universitaire Wallonie-Bruxelles, Place du Parc 20, B-7000 Mons (Belgium)

2011-09-15

45

Surface Inspection using fourier transform infrared spectroscopy.  

National Technical Information Service (NTIS)

The use of reflectance Fourier transform infrared (FTIR) spectroscopy as a tool for surface inspection is described. Laboratory instruments and portable instruments can support remote sensing probes that can map chemical contaminants on surfaces. Detectio...

G. L. Powell N. R. Smyrl D. M. Williams H. M. Meyers T. E. Barber

1994-01-01

46

Historical notes on the fast Fourier transform  

Microsoft Academic Search

The fast Fourier transform algorithm has a long and interesting history that has only recently been appreciated. In this paper, the contributions of many investigators are described and placed in historical perspective.

JAMES W. COOLEY; PETER A. W. LEWIS; PETER D. WELCH

1967-01-01

47

Image processing and the Arithmetic Fourier Transform  

SciTech Connect

A new Fourier technique, the Arithmetic Fourier Transform (AFT) was recently developed for signal processing. This approach is based on the number-theoretic method of Mobius inversion. The AFT needs only additions except for a small amount of multiplications by prescribed scale factors. This new algorithm is also well suited to parallel processing. And there is no accumulation of rounding errors in the AFT algorithm. In this reprint, the AFT is used to compute the discrete cosine transform and is also extended to 2-D cases for image processing. A 2-D Mobius inversion formula is proved. It is then applied to the computation of Fourier coefficients of a periodic 2-D function. It is shown that the output of an array of delay-line (or transversal) filters is the Mobius transform of the input harmonic terms. The 2-D Fourier coefficients can therefore be obtained through Mobius inversion of the output of the filter array.

Tufts, D.W.; Fan, Z.; Cao, Z.

1989-01-01

48

Quantum Lower Bound for Recursive Fourier Sampling  

Microsoft Academic Search

One of the earliest quantum algorithms was discovered by Bernstein and Vazirani, for a problem called Recursive Fourier Sampling. This paper shows that the Bernstein-Vazirani algorithm is not far from optimal. The moral is that the need to \\

Scott Aaronson

2002-01-01

49

Fast Hardware Fourier Transformation Through Counting  

Microsoft Academic Search

Hardware Fourier transformations are considered with the goal of increasing speed through parallel operation. Two designs in which the basic element is a fast counter are developed. One is applicable when the number of transformed points N is prime while the other, requiring somewhat more hardware, is applicable to all N.

SHALHAV ZOHAR

1973-01-01

50

Fourier Transform of Untransformable Signals Using Pattern Recognition Technique  

Microsoft Academic Search

In this paper we are highlighting the signals that are not Fourier transformable and give its Fourier transform using PCA (Principle Component Analysis), lDA (linear Discriminant Analysis). Such signals are step signal, signum, etc. Basically Fourier transform transforms time domain signal into frequency domain and after transformation describes what frequencies original signal have. Principle Component Analysis is a way of

Varun Gupta; G. Singh; M. Mittal; Sharvan Kumar Pahuja

2010-01-01

51

Comparison of Arithmetic Requirements for the PFA (Prime Factor Algorithm), WFTA (Winograd Fourier Transform Algorithm), SWIFT, MFFT (Mixed Radix Fast Fourier Transform), FFT (Fast Fourier Transform) and DFT (Discrete Fourier Transform) Algorithms.  

National Technical Information Service (NTIS)

This discrete Fourier transform (DFT) is a powerful reversible mapping transform for discrete data sequences with mathematical properties analogous to those of the Fourier transform. The DFT can be used for spectral analysis of time series, fast correlati...

R. C. Hicks

1982-01-01

52

Elliptic Discrete Fourier Transforms of Type II  

Microsoft Academic Search

This paper presents a novel concept of the iV-point elliptic DFT of type II (EDFT-II), by considering and generalizing the iV-point DFT in the real space R2N. In the definition of such Fourier transformation, the block-wise representation of the matrix of the DFT is reserved and the Givens transformations for multiplication by the twiddle coefficients are substituted by other basic

Artyom M. Grigoryan

2009-01-01

53

Uniform time-sampling Fourier transform spectroscopy.  

PubMed

We show that uniform time sampling of both the reference and the target channels in a continuous scanning Fourier transform spectrometer is a simple and versatile way of extending the Nyquist limit shorter than the wavelength of the reference channel. We also discuss the benefits of recording the reference channel when intensity calibrating the target data. PMID:18253194

Brasunas, J C; Cushman, G M

1997-04-01

54

Fourier transform infrared imaging of bone.  

PubMed

Fourier transform infrared imaging (FTIRI) is a technique that can be used to analyze the material properties of bone using tissue sections. In this chapter I describe the basic principles of FTIR and the methods for capturing and analyzing FTIR images in bone sections. PMID:22130948

Paschalis, Eleftherios P

2012-01-01

55

Radar backscatter analysis using fractional Fourier transform  

Microsoft Academic Search

This paper focuses on analyzing radar backscatter returns using the fractional Fourier transform. This study is motivated by two factors: first, to examine the radar backscatter mechanism of standard small targets; and second, to extract pertinent scattering features that can be used in target recognition. Radar returns have been examined using time-frequency analysis techniques, particularly those targets with dispersive scattering

Ismail I. Jouny

2004-01-01

56

Livermore Imaging Fourier Transform Infrared Spectrometer (LIFTIRS)  

SciTech Connect

Lawrence Livermore National Laboratory is currently operating a hyperspectral imager, the Livermore Imaging Fourier Transform Infrared Spectrometer (LIFTIRS). This instrument is capable of operating throughout the infrared spectrum from 3 to 12.5 {mu}m with controllable spectral resolution. In this presentation we report on it`s operating characteristics, current capabilities, data throughput and calibration issues.

Carter, M.R.; Bennett, C.L.; Fields, D.J.; Lee, F.D.

1995-05-10

57

Fourier Transform Spectroscopy, Eleventh International Conference. Proceedings  

SciTech Connect

These proceedings represent the papers presented at the Eleventh International Conference on Fourier Transform Spectroscopy held in August, 1997 in Athens, Georgia, USA. The Conference provided an atmosphere for people of diverse backgrounds to congregate and exchange information. The topics discussed included applications of Fourier transform spectroscopy to surface science, biological systems, atmospheric science, forensics and textiles, etc. Biochemical and biomedical studies utilizing Fourier Transform infrared spectroscopy formed a large section of the Conference Applications to semiconductor industry, namely monitoring of CVD processes and photoresists were also discussed. Most of the applications were in the near and mid infrared, with a few extending to the far infrared and visible regions of the electromagnetic spectrum. In the Keynote Address, Fourier Transform Ion Cyloctron Resonance Spectroscopy was reviewed by Professor Alan G. Marshall of the National High Magnetic Field Laboratory in Florida. Altogether 152 papers were presented at the Conference and out of these, 15 have been abstracted for the Energy, Science and Technology database. (AIP)

de Haseth, J.A. [Department of Chemistry, University of Georgia, Atlanta, GA 30602-2556 (United States)

1998-05-01

58

A bibliography on dispersive Fourier transform spectronomy  

Microsoft Academic Search

A bibliography is presented of 112 source publications and 20 review articles and books containing information on the technique of dispersive Fourier transform spectrometry (DFTS), and its application to the study of gases, liquids and solids. An index is provided to the source publications which includes a list of nearly 100 materials which have been studied by DFTS, and sections

J. R. Birch; T. J. Parker

1979-01-01

59

Fourier Transform and Reflective Imaging Pyrometry  

SciTech Connect

A stationary Fourier transform pyrometer was used to record mid-wavelength IR spectra in dynamic shock experiments. The gated-IR camera used with this system was also used to record images of light produced and light reflected from shocked metals in order to constrain the dynamic emissivity and provide temperature estimates. This technique will be referred to as reflective imaging pyrometry.

Stevens, G. D.

2011-07-01

60

Quantum transport efficiency and Fourier's law.  

PubMed

We analyze the steady-state energy transfer in a chain of coupled two-level systems connecting two thermal reservoirs. Through an analytic treatment we find that the energy current is independent of the system size, hence violating Fourier's law of heat conduction. The classical diffusive behavior in Fourier's law of heat conduction can be recovered by introducing decoherence to the quantum systems constituting the chain. We relate these results to recent discussions of energy transport in biological light-harvesting systems, and discuss the role of quantum coherence and entanglement. PMID:23367904

Manzano, Daniel; Tiersch, Markus; Asadian, Ali; Briegel, Hans J

2012-12-13

61

Fractional Fourier transform for elliptical Gaussian beams  

NASA Astrophysics Data System (ADS)

Based on the definition of fractional Fourier transform (FRT), an analytical formula is derived for the FRT of elliptical Gaussian beam (EGB) by using a tensor method. The corresponding tensor ABCD law for performing the FRT of EGB is obtained. The connection between the FRT formula and the generalized Collins formula is discussed. By using the derived formula, the influences of the fractional order on the properties of EGB in the fractional Fourier plane are studied in detail. The derived formulae provide a powerful tool for analyzing and calculating the FRT of EGB.

Cai, Yangjian; Lin, Qiang

2003-03-01

62

Mosaic imaging Fourier transform spectrometer applications  

Microsoft Academic Search

A high-speed passive FTIR imaging spectrometer has been developed and tested in airborne flight tests on both fixed wing and helicopter platforms. This sensor was developed and flown from 2000 to 2005 in conjunction with various organizations, and is known as the Turbo FT. The Turbo FT is a laser-less rotary high speed Fourier Transform Infra-Red (FTIR) spectrometer capable of

Winthrop Wadsworth; Jens Peter Dybwad; Drew Stone

2005-01-01

63

Periodicity-induced generalized Fourier transform pair  

Microsoft Academic Search

The field radiated by an infinite periodic structure can be expressed in terms of Floquet waves (FWs), both in the frequency domain (FD) and time domain (TD) (see Felsen, L.B. and Capolino, F., IEEE Trans. Antennas Propagat., vol.48, p.921-31, 2000). A new periodicity-induced generalized Fourier transform (FT) pair is derived relating FD-FWs to TD-FWs and vice versa, based on tabulated

Filippo Capolino

2002-01-01

64

Electrocardiogram analysis through time discrete Fourier transform  

NASA Astrophysics Data System (ADS)

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.

Lancaster, Cameron; Zhang, Guoping

2011-03-01

65

Fast classical and quantum fractional Haar wavelet transforms  

Microsoft Academic Search

The fractional Fourier transform (FRFT) is one-parametric generalization of the classical Fourier transform. FRFT was introduced in the 1980s and found a lot of applications in signal processing. The time and spectral domains are both the special cases of the functional Fourier domain. They correspond to the 0th and 1st fractional Fourier domains, respectively. We introduce the classical and quantum

Valeri Labunets; Ekaterina Labunets-Rundblad; Jaakko Astola

2001-01-01

66

Quantum indeterminism: a direct consequence of Fourier ontology  

NASA Astrophysics Data System (ADS)

Fourier ontology and consequent quantum indeterminism and the way to overcome it shall be discussed. Furthermore it shall be proven that recent experimental technology goes far beyond the limits imposed by Heisenberg indetermination relations. These experiments are perfectly integrated in the new causal nonlinear quantum physics. Keywords: Orthodox quantum mechanics, Fourier ontology, Heisenberg indetermination relations, nonlinear quantum physics, general uncertainty relations, beyond Heisenberg limits.

Croca, J. R.

2013-10-01

67

The prosaic Laplace and Fourier transform  

SciTech Connect

Integral Transform methods play an extremely important role in many branches of science and engineering. The ease with which many problems may be solved using these techniques is well known. In Electrical Engineering especially, Laplace and Fourier Transforms have been used for a long time as a way to change the solution of differential equations into trivial algebraic manipulations or to provide alternate representations of signals and data. These techniques, while seemingly overshadowed by today`s emphasis on digital analysis, still form an invaluable basis in the understanding of systems and circuits. A firm grasp of the practical aspects of these subjects provides valuable conceptual tools. This tutorial paper is a review of Laplace and Fourier Transforms from an applied perspective with an emphasis on engineering applications. The interrelationship of the time and frequency domains will be stressed, in an attempt to comfort those who, after living so much of their lives in the time domain, find thinking in the frequency domain disquieting. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

Smith, G.A. [Brookhaven National Laboratory, Upton, New York (United States)

1995-05-05

68

Fourier transform methods in local gravity modeling  

NASA Astrophysics Data System (ADS)

New algorithms for computing the terrain connections, all components of the attraction of the topography at the topographic surface, and the gradients of these attractions were developed using Fourier transforms; in contrast to methods currently in use, all divergences of the integrals are removed during the analysis. The FFT methods described allow many of the computations employed in modeling the gravity field on a local basis to be performed very efficiently using gridded digital elevation data and mean gravity values estimated from the original gravity observations. Results using these methods were shown to agree with those obtained by traditional methods.

Harrison, J. C.; Dickinson, M.

1989-06-01

69

Advanced Techniques for Fourier Transform Wavefront Reconstruction  

SciTech Connect

The performance of Fourier transform (FT) reconstructors in large adaptive optics systems with Shack-Hartmann sensors and a deformable mirror is analyzed. FT methods, which are derived for point-based geometries, are adapted for use on the continuous systems. Analysis and simulation show how to compensate for effects such as misalignment of the deformable mirror and wavefront sensor gain. Further filtering methods to reduce noise and improve performance are presented. All these modifications can be implemented at the filtering stage, preserving the speed of FT reconstruction. Simulation of a large system shows how compensated FT methods can have equivalent or better performance to slower vector-matrix-multiply reconstructions.

Poyneer, L A

2002-08-05

70

Fourier transform infrared spectroscopy of peptides.  

PubMed

Fourier transform infrared (FTIR) spectroscopy provides data that are widely used for secondary structure characterization of peptides. A wide array of available sampling methods permits structural analysis of peptides in diverse environments such as aqueous solution (including optically turbid media), powders, detergent micelles, and lipid bilayers. In some cases, side chain vibrations can also be resolved and used for tertiary structure and chemical analysis. Data from several low-resolution spectroscopic techniques, including FTIR, can be combined to generate an empirical phase diagram, an overall picture of peptide structure as a function of environmental conditions that can aid in the global interpretation of large amounts of spectroscopic data. PMID:24146410

Bakshi, Kunal; Liyanage, Mangala R; Volkin, David B; Middaugh, C Russell

2014-01-01

71

Fourier transform infrared spectroscopy of deuterated proteins  

NASA Astrophysics Data System (ADS)

We report on Fourier transform spectra of deuterated proteins: Bovine Serum Albumin, Leptin, Insulin-like Growth Factor II, monoclonal antibody to ovarian cancer antigen CA125 and Osteopontin. The spectra exhibit changes in the relative amplitude and spectral width of certain peaks. New peaks not present in the non-deuterated sample are also observed. Ways for improving the deuteration of proteins by varying the temperature and dilution time are discussed. We propose the use of deuterated proteins to increase the sensitivity of immunoassays aimed for early diagnostic of diseases most notably cancer.

Marcano O., A.; Markushin, Y.; Melikechi, N.; Connolly, D.

2008-08-01

72

Velocity synchronized fourier transform hologram camera system.  

PubMed

Methods for recording holograms of hypervelocity particles were studied. It was assumed that the particle would move an appreciable distance during the exposure time. The problem was to find a method of maintaining stationary hologram interference fringes as the object moved within the field of view. A Fourier transform method employing an interferometer and using a reference beam produced by back reflection from the object was found to be conceptually correct. The stationarity of the approach was demonstrated experimentally. It was also proven possible to change arbitrarily the position of the reconstructed image relative to the hologram axis. PMID:20076335

Dyes, W A; Kellen, P F; Klaubert, E C

1970-05-01

73

Miniature Fourier transform instrument for radiation thermometry  

NASA Astrophysics Data System (ADS)

A miniature Fourier transform (FT) spectrometer has been tested as a device for remotely measuring the temperature of a high stability/emissivity blackbody. The commercially manufactured device is based on the novel design of a polarizing Wollaston prism spatial domain interferometer, with a Si diode array detector, and without any moving parts. The measurement of temperature using Planck's law showed a consistent nonlinear effect. This results in an error of the order of 1% for measurement of temperatures 500 K and above. Planned calibration measurements should reduce the nonlinearity related error and improve the FT temperature measurement.

Dunmore, Franklin J.; Hanssen, Leonard M.

1998-06-01

74

Fourier Transforms Simplified: Computing an Infrared Spectrum from an Interferogram  

ERIC Educational Resources Information Center

|Fourier transforms are used widely in chemistry and allied sciences. Examples include infrared, nuclear magnetic resonance, and mass spectroscopies. A thorough understanding of Fourier methods assists the understanding of microscopy, X-ray diffraction, and diffraction gratings. The theory of Fourier transforms has been presented in this…

Hanley, Quentin S.

2012-01-01

75

Fourier Transforms Simplified: Computing an Infrared Spectrum from an Interferogram  

ERIC Educational Resources Information Center

Fourier transforms are used widely in chemistry and allied sciences. Examples include infrared, nuclear magnetic resonance, and mass spectroscopies. A thorough understanding of Fourier methods assists the understanding of microscopy, X-ray diffraction, and diffraction gratings. The theory of Fourier transforms has been presented in this "Journal",…

Hanley, Quentin S.

2012-01-01

76

Interference analysis of multicarrier systems based on affine fourier transform  

Microsoft Academic Search

Multicarrier techniques based on affine Fourier transform (AFT) have been recently proposed for transmission in the wireless channels. The AFT represents a generalization of the Fourier and fractional Fourier transform. We derive the exact and approximated interference power, upper bound and measure of applicability for the AFT based multicarrier (AFT-MC) system. It is demonstrated that the AFT-MC system effectively minimizes

Djuro Stojanovic; Igor Djurovic; Branimir R. Vojcic

2009-01-01

77

Fractional Fourier transform in optics - a new perspective  

NASA Astrophysics Data System (ADS)

This paper presents the optical implementation of fractional Fourier transform using bulk optics in a new light. We used a two-lens Fourier transforming setup. The field distribution at the half order fractional Fourier transform plane is obtained using Fresnel transform as the analysing tool. It is shown that the half-order fractional Fourier transform of any function is a product of Fresnel function and the Fourier transform of the product of the given function in a reduced coordinate with another Fresnel function. Then analytical expressions are also deduced for the nature of the half order Fourier transform of a plane wave, delta function, sinusoidal grating, rectangular aperture as well as Gaussian input function. We verified our theoretical prediction experimentally with a square-top grating as the objectE The effect of spatial filtering at the half transform plane is also explored.

Sanyal, Sucharita; Ghosh, Ajay; Dey, Kashi Nath

78

Two-dimensional fourier transform spectrometer  

DOEpatents

The present invention relates to a system and methods for acquiring two-dimensional Fourier transform (2D FT) spectra. Overlap of a collinear pulse pair and probe induce a molecular response which is collected by spectral dispersion of the signal modulated probe beam. Simultaneous collection of the molecular response, pulse timing and characteristics permit real time phasing and rapid acquisition of spectra. Full spectra are acquired as a function of pulse pair timings and numerically transformed to achieve the full frequency-frequency spectrum. This method demonstrates the ability to acquire information on molecular dynamics, couplings and structure in a simple apparatus. Multi-dimensional methods can be used for diagnostic and analytical measurements in the biological, biomedical, and chemical fields.

DeFlores, Lauren; Tokmakoff, Andrei

2013-09-03

79

FFTW: Fastest Fourier Transform in the West  

NASA Astrophysics Data System (ADS)

FFTW is a C subroutine library for computing the discrete Fourier transform (DFT) in one or more dimensions, of arbitrary input size, and of both real and complex data (as well as of even/odd data, i.e. the discrete cosine/sine transforms or DCT/DST).Benchmarks performed on a variety of platforms show that FFTW's performance is typically superior to that of other publicly available FFT software, and is even competitive with vendor-tuned codes. In contrast to vendor-tuned codes, however, FFTW's performance is portable: the same program will perform well on most architectures without modification.The FFTW library is required by other codes such as StarCrash and Hammurabi.

Frigo, Matteo; Johnson, Steven G.

2012-01-01

80

Fourier transform general formula for systematic potentials.  

PubMed

For calculating molecular integrals of systematic potentials, a three-dimensional (3D) Fourier transform general formula can be derived, by the use of the Abel summation method. The present general formula contains all 3D Fourier transform formulas which are well known as Bethe-Salpeter formulas (Bethe and Salpeter, Handbuch der Physik, Bd. XXXV, 1957) as special cases. It is shown that, in several of the Bethe-Salpeter formulas, the integral does not converge in the meaning of the Riemann integral but converges in the meaning of a hyper function as the Schwartz distribution. For showing an effectiveness of the present general formula, the convergence condition of molecular integrals is derived generally for all of the present potentials. It is found that molecular integrals can be converged in the meaning of the Riemann integral for the present potentials, except for those for extra super singular potentials. It is also found that the convergence condition of molecular integrals over the Slater-type orbitals is exactly the same as that of the corresponding integrals over the Gaussian-type orbitals for the present systematic potentials. For showing more effectiveness, the molecular integral over the gauge-including atomic orbitals is derived for the magnetic dipole-same-dipole interaction. PMID:22298234

Ishida, Kazuhiro

2012-02-01

81

Fourier Transform Light Scattering of Tissues  

NASA Astrophysics Data System (ADS)

We review the basic principles of light-tissue interaction and common methods of investigation. The mathematical framework for describing weakly scattering regime (the Born approximation) as well as the strong scattering regime (the diffusion equation) are described. Traditional techniques based on polarization, time-resolved, single and multiple scattering are reviewed. We then introduce Fourier transform light scattering (FTLS), which is a recent development from our own laboratory. FTLS is the spatial analogue of Fourier transform spectroscopy, in the sense that it provides angular scattering (spatial frequency) data from phase and amplitude measurements in the spatial (image) domain. We show that FTLS can be used as a diagnostic tool by translating the quantitative phase information into data of clinical relevance. Further, FTLS allows us to extract scattering parameters of the tissue from imaging unlabeled, thin tissue slices, using a relationship which we call the scattering-phase theorem. Using these measurements, FTLS can predict the outcome of many other experiments, including time resolved and enhanced backscattering experiments.

Kim, Taewoo; Sridharan, Shamira; Popescu, Gabriel

82

The Fourier transform of tubular densities  

NASA Astrophysics Data System (ADS)

We consider the Fourier transform of tubular volume densities, with arbitrary axial geometry and (possibly) twisted internal structure. This density can be used to represent, among others, magnetic flux or the electron density of biopolymer molecules. We consider tubes of both finite radii and unrestricted radius. When there is overlap of the tube structure the net density is calculated using the super-position principle. The Fourier transform of this density is composed of two expressions, one for which the radius of the tube is less than the curvature of the axis and one for which the radius is greater (which must have density overlap). This expression can accommodate an asymmetric density distribution and a tube structure which has non-uniform twisting. In addition we give several simpler expressions for isotropic densities, densities of finite radius, densities which decay at a rate sufficient to minimize local overlap and finally individual surfaces of the tube manifold. These simplified cases can often be expressed as arclength integrals and can be evaluated using a system of first-order ODEs.

Prior, C. B.; Goriely, A.

2012-06-01

83

CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES: Fourier transform technique in variational treatment of two-electron parabolic quantum dot  

NASA Astrophysics Data System (ADS)

In this work, we propose an efficient method of reducing the computational effort of variational calculation with a Hylleraas-like trial wavefunction. The method consists of introducing integral transforms for the terms as rk12 exp (-?r12) which provide the calculation of the expectation value of energy and the relevant matrix elements to be done analytically over single-electron coordinates instead of Hylleraas coordinates. We have used this method to calculate the ground state energy of a two-electron system in a spherical dot and a disk-like quantum dot separately. Under parabolic confinement potential and within effective mass approximation size and shape effects of quantum dots on the ground state energy of two electrons have been investigated. The calculation shows that our results even with a small number of basis states are in good agreement with previous theoretical results.

?akiro?lu, S.; Y?ld?z, A.; Do?an, Ü.; Akgüngör, K.; Epik, H.; Ergün, Y.; Sar?, H.; ?, Sökmen

2009-08-01

84

A General Spectral Transformation Simultaneously Including a Fourier Transformation and a Laplace Transformation.  

National Technical Information Service (NTIS)

A general spectral transformation is proposed and described. Its spectrum can be interpreted as a Fourier spectrum or a Laplace spectrum. The laws and functions of the method are discussed in comparison with the known transformations, and a sample applica...

H. Marko

1978-01-01

85

Fast nD Fourier-Heisenberg-Weyl transforms  

Microsoft Academic Search

In this work we study the harmonic analysis of functions on the n-D Heisenberg groups H over the Galois field GF(p) for generating Gabor atoms. Analogous to the Fourier transform, the expansion of functions on the basis of irreducible complex matrix representations of the Heisenberg group defines the generalized Fourier transform on this group, or, simply, the Fourier-Heisenberg transform. The

V. Labunets; E. Rundblad-Labunets; J. Astola; K. Egiazarian

2000-01-01

86

Birefringent prism based Fourier transform spectrometer.  

PubMed

This paper presents the design of a rugged and compact Fourier transform spectrometer (FTS) utilizing a birefringent prism, a pair of polarizers and a linear CCD array. This design improves on existing FTS by eliminating moving parts and spreading the optical path difference (OPD) spatially (rather than temporal scanning), making the system smaller, more reliable, and dramatically reducing measurement times. Both the theoretical models for the design and experimental results of the prototype are presented. The optical performance is tested using LEDs of known wavelengths, with the fringe counting technique employed during interferogram acquisition to ensure accurate sampling of the interferogram at constant OPD intervals. Reconstructing the spectra showed that the detected wavelengths deviated from the actual wavelengths by less than 1 nm. PMID:22555737

Huang, Chu-Yu; Wang, Wei-Chih

2012-05-01

87

Fourier transform spectrometer controller for partitioned architectures  

NASA Astrophysics Data System (ADS)

The current trend in spacecraft computing is to integrate applications of different criticality levels on the same platform using no separation. This approach increases the complexity of the development, verification and integration processes, with an impact on the whole system life cycle. Researchers at ESA and NASA advocated for the use of partitioned architecture to reduce this complexity. Partitioned architectures rely on platform mechanisms to provide robust temporal and spatial separation between applications. Such architectures have been successfully implemented in several industries, such as avionics and automotive. In this paper we investigate the challenges of developing and the benefits of integrating a scientific instrument, namely a Fourier Transform Spectrometer, in such a partitioned architecture.

Tamas-Selicean, D.; Keymeulen, D.; Berisford, D.; Carlson, R.; Hand, K.; Pop, P.; Wadsworth, W.; Levy, R.

88

Efficient VLSI Architectures for the Arithmetic Fourier Transform (AFT)  

Microsoft Academic Search

Recently, a new method based on the number-the- oretic Mobius inversion formula has been proposed for the computation of the discrete Fourier transform (DFT). The arithmetic Fourier transform (AFT), as this method is known, computes N = 2L + 1 Fourier coefficients (in one dimension) with as few as 3N real multiplications and 1.5N' real additions. However, the number count

Brian T. Kelley; Vijay K. Madisetti

1993-01-01

89

Local Fractional Fourier's Transform Based on the Local Fractional Calculus  

Microsoft Academic Search

A new modeling for the local fractional Fourier's transform containing the local fractional calculus is investigated in fractional space. The properties of the local fractional Fourier's transform are obtained and two examples for the local fractional systems are investigated in detail.

Xiaojun Yang; Zongxin Kang; Changhe Liu

2010-01-01

90

A Novel TDLMS Algorithm Based on the Fractional Fourier Transform  

Microsoft Academic Search

LMS adaptive filtering is widely used in smart antenna and space-time signal processing. The transform domain LMS (TDLMS) adaptive filtering is a very popular alternative technique to general LMS-type algorithms. As Fourier analysis is one of the most frequently used tools in signal processing, this paper first introduces fractional Fourier transform (FRFT) and part of its properties, and then presents

Gang Su; Guangxi Zhu

2006-01-01

91

Fractional Fourier transforms and their optical implementation. II  

Microsoft Academic Search

Fourier transforms of fractional order a are defined in a manner such that the common Fourier transform is a special case with order a = 1. An optical interpretation is provided in terms of quadratic graded index media and discussed from both wave and ray viewpoints. Several mathematical properties are derived. 1. MOTIVATION It is often the case that an

Haldun M. Ozaktas; David Mendlovic

1993-01-01

92

THE DISCRETE FOURIER TRANSFORM AND CYCLIC CONVOLUTION ON INTEGRAL LATTICES  

Microsoft Academic Search

A discrete Fourier transform and a cyclic convolution are constructed on an arbitrary integral lattice. The construction includes as a special case the usual discrete Fourier transform and the usual cyclic convolution. Applications to questions of interpolation of functions and digital signal processing are considered. Methods in the spectral theory of automorphic functions are used to investigate questions in approximation

V A Bykovski?

1989-01-01

93

Mosaic imaging Fourier transform spectrometer applications  

NASA Astrophysics Data System (ADS)

A high-speed passive FTIR imaging spectrometer has been developed and tested in airborne flight tests on both fixed wing and helicopter platforms. This sensor was developed and flown from 2000 to 2005 in conjunction with various organizations, and is known as the Turbo FT. The Turbo FT is a laser-less rotary high speed Fourier Transform Infra-Red (FTIR) spectrometer capable of very high speed, spectral resolution to 1 cm-1, and operation in rugged environments. For these tests, the sensor was run at 8 cm-1 resolution and 50-100 scans per second with either a single element or a 2x8 element LWIR detector. An on-board auto-calibrating blackbody accessory was developed and automated chemical detection software was developed. These features allow in-flight calibration, facilitated detection of target gas clouds, and reported detections to an on-board targeting computer. This paper will discuss the system specifications, sensor performance, and field results from various experiments. Current work on development of an 8x8 pixel Turbo FT system will also be presented.

Wadsworth, Winthrop; Dybwad, Jens Peter; Stone, Drew

2005-06-01

94

Fourier and Schur-Weyl transforms applied to XXX Heisenberg magnet  

NASA Astrophysics Data System (ADS)

Similarities and differences between Fourier and Schur-Weyl transforms have been discussed in the context of a one-dimensional Heisenberg magnetic ring with N nodes. We demonstrate that main difference between them correspond to another partitioning of the Hilbert space of the magnet. In particular, we point out that application of the quantum Fourier transform corresponds to splitting of the Hilbert space of the model into subspaces associated with the orbits of the cyclic group, whereas, the Schur-Weyl transform corresponds to splitting into subspaces associated with orbits of the symmetric group.

Jakubczyk, P.; Lulek, T.; Jakubczyk, D.; Lulek, B.

2010-03-01

95

Fourier transform infrared microspectroscopy of endocarditis vegetation.  

PubMed

The objectives of this work were to compare the infrared spectra of bacterial endocarditis vegetation with those of native valvular tissue and the infrared spectra of vegetation bacterial masses with those of surrounding vegetation tissue. Streptococcal aortic endocarditis was induced in three rabbits. Vegetation slices were cryo-sectioned for study by Fourier transform infrared (FT-IR) microspectroscopy. Valvular apparatus, vegetation, and bacterial masses within the vegetation were localized on hematoxylin and eosin (H&E) stained contiguous slices. Infrared images of whole vegetations and images of bacterial masses were acquired with apertures set to 80 x 80 and 20 x 20 microm, respectively. Valvular apparatus and vegetation showed different infrared spectra, mainly in the amide I and amide II bands (1674-1518 cm(-1)), and at about 1450, 1400, 1340, 1280, 1240, 1200, 1080, and 1030 cm(-1). Valvular collagen, elastin, and proteoglycans may explain these differences. Bacterial masses and surrounding vegetation showed different infrared patterns, mainly in the amide I and amide II bands and in the 1142-991 cm(-1) carbohydrate spectral range. Bacterial nucleic acids and polysaccharides may partly explain these differences. Study of experimental endocarditis vegetation using FT-IR microspectroscopy distinguishes (1) the vegetation from the valvular tissue, and (2) the bacterial masses from the surrounding tissue. This study demonstrates for the first time that FT-IR microspectroscopy is able to detect bacterial growth in infected tissue. FT-IR microspectroscopy appears to be a useful tool for investigation of the biochemical structure of endocarditis vegetation. PMID:20719053

Batard, Eric; Jamme, Frédéric; Boutoille, David; Jacqueline, Cédric; Caillon, Jocelyne; Potel, Gilles; Dumas, Paul

2010-08-01

96

Vector coding algorithms for multidimensional discrete Fourier transform  

NASA Astrophysics Data System (ADS)

A new fast algorithm is presented for the multidimensional discrete Fourier transform (DFT). This algorithm is derived using an interesting technique called "vector coding" (VC), and we call it the vector-coding fast Fourier transform (VC-FFT) algorithm. Since the VC-FFT is an extension of the Cooley-Tukey algorithm from 1-D to multidimensional form, the structure of the program is as simple as the Cooley-Tukey fast Fourier transform (FFT). The new algorithm significantly reduces the number of multiplications and recursive stages. The VC-FFT therefore comprehensively reduces the complexity of the algorithm as compared with other current multidimensional DFT algorithms.

Chen, Zhaodou; Zhang, Lijing

2008-02-01

97

VLSI fast Fourier transform digital signal processor chip  

NASA Astrophysics Data System (ADS)

A high performance VLSI chip has been designed to perform the Fast Fourier Transform (FFT) used in digital signal processing systems. This Bendix proprietary, custom digital signal processor (DSP) chip performs a 128 Point FFT and has a wide range of avionics and aerospace applications ranging from radar to sonar systems. The chip employs a novel algorithm designed to efficiently implement the FFT with a minimum of hardware by eliminating all multiply operations while achieving high throughput rates. It executes both the Fast Fourier Transform and the Inverse Fast Fourier Transform which are powerful tools in frequency domain analysis.

Hutchinson, S. A.; Kagey, D. R.; Kantowski, J. W.; Miller, M. A.

98

Securing information using fractional Fourier transform in digital holography  

NASA Astrophysics Data System (ADS)

In this paper, we demonstrate a fully digital technique using double random Fourier, and fractional plane encryption. The input image to be encrypted is multiplied by a phase mask, and either its Fourier or fractional Fourier transform is obtained. Using interference with a wave from another random phase mask, the encrypted data (Fourier or fractional hologram) is recorded digitally. The decryption key is also recorded as a digital hologram, called the key hologram. An electronic key generated in the PC is multiplied with the encrypted hologram, and a Fourier or fractional Fourier transform (encrypted image) is obtained. This decryption key hologram, the electronically generated key (random phase code), and the encrypted image can be transmitted through communication channels. The retrieval is carried out by all-digital means.

Kumar Nishchal, Naveen; Joseph, Joby; Singh, Kehar

2004-05-01

99

Optical signal processing - Fourier transforms and convolution/correlation  

NASA Astrophysics Data System (ADS)

The application of Fourier techniques and linear-systems theory to the analysis and synthesis of optical systems is described in a theoretical review, and Fourier-based optical signal-processing methods are considered. Topics examined include monochromatic wave fields and their phasor representation, wave propagation, Fourier-transform and spectrum analysis with a spherical lens, coherent and incoherent imaging and spatial filtering, and a channelized spectrum analyzer (using both spherical and cylindrical lenses) for multiple one-dimensional input signals.

Rhodes, William T.

100

Analysis of coaxial photonic crystal transmittance by Fourier transform  

NASA Astrophysics Data System (ADS)

In this work, we present an analysis of harmonic frequency transmission filters based on one-dimensional photonic crystals using a Fourier transform approach. This approach relates the photonic crystal transmittance with the Fourier transform of the logarithmic derivate of their refraction index profile. We compare this Fourier approach with the exact transmission calculated by means of the transfer matrix method. We study the accuracy of different functions proposed in the literature that relate the Fourier transform of the index profile with the transmittance. This Fourier approach provides a more intuitive understanding of the transmission properties of one-dimensional photonic crystals. We experimentally demonstrate these properties by using coaxial cables of different impedances. This kind of electrical system is easier to perform experimentally and reproduces, in the radiofrequency range, the properties of one-dimensional photonic crystals.

Sanchez-Lopez, M. M.; Cos, J.; Davis, J. A.; Miller, D. A.; Moreno, I.; Velasquez, P.

2005-07-01

101

Signal Approximation via the Gopher Fast Fourier Transform  

NASA Astrophysics Data System (ADS)

We consider the problem of quickly estimating the best ?-term Fourier representation for a given frequency-sparse band-limited signal (i.e., function) f: [0,2?]-->¢. In essence, this requires the identification of ? of the largest magnitude frequencies of \\vf ?¢N, and the estimation their Fourier coefficients. Randomized sublinear-time Monte Carlo algorithms, which have a small probability of failing to output accurate answers for each input signal, have been developed for solving this problem [1, 2]. These methods were implemented as the Ann Arbor Fast Fourier Transform (AAFFT) and empirically evaluated in [3]. In this paper we present and evaluate the first implementation, called the Gopher Fast Fourier Transform (GFFT), of the more recently developed sparse Fourier transform techniques from [4]. Our experiments indicate that different variants of GFFT generally outperform AAFFT with respect to runtime and sample usage.

Ben Segal, I.; Iwen, M. A.

2010-11-01

102

A shattered survey of the Fractional Fourier Transform  

Microsoft Academic Search

In this survey paper we introduce the reader to the notion of the fractional Fourier transform, which may be considered as a fractional power of the classical Fourier trans- form. It has been intensely studied during the last decade, an attention it may have partially gained because of the vivid interest in time-frequency analysis methods of signal processing, like wavelets.

A. Bultheel

103

Arithmetic Fourier Transform (AFT): Iterative Computation and Image Processing Applications.  

National Technical Information Service (NTIS)

A Fourier analysis method using an iterative Arithmetic Fourier Transform (AFT) is presented. It overcomes the difficulty of dense, Farey-fraction sampling which is inherent in the original AFT algorithm. This disadvantage of the AFT is turned into an adv...

D. W. Tufts H. Chen

1992-01-01

104

FT Digital Filtering and Simulating Fourier transform Apodization via Excel  

NSDL National Science Digital Library

This report presents an excel spreadsheet which simulates Fourier Transform apodization filtering on a noisy signal that contains either white or an environmental noise source. Users may download the report in PDF file format.

Overway, Ken

2008-02-04

105

Technique for the metrology calibration of a Fourier transform spectrometer  

SciTech Connect

A method is presented for using a Fourier transform spectrometer (FTS) to calibrate the metrology of a second FTS. This technique is particularly useful when the second FTS is inside a cryostat or otherwise inaccessible.

Spencer, Locke D.; Naylor, David A

2008-11-10

106

Feasibility Investigation of Integrated Optics Fourier Transform Devices.  

National Technical Information Service (NTIS)

The possibility of producing an integrated optics data processing device based upon Fourier transformations or other parallel processing techniques, and the ways in which such techniques may be used to upgrade the performance of present and projected NASA...

C. M. Verber D. W. Vahey V. E. Wood R. P. Kenan N. F. Hartman

1977-01-01

107

The quest for conformal geometric algebra Fourier transformations  

NASA Astrophysics Data System (ADS)

Conformal geometric algebra is preferred in many applications. Clifford Fourier transforms (CFT) allow holistic signal processing of (multi) vector fields, different from marginal (channel wise) processing: Flow fields, color fields, electro-magnetic fields, ... The Clifford algebra sets (manifolds) of -1 lead to continuous manifolds of CFTs. A frequently asked question is: What does a Clifford Fourier transform of conformal geometric algebra look like? We try to give a first answer.

Hitzer, Eckhard

2013-10-01

108

Herz spaces and restricted summability of Fourier transforms and Fourier series  

NASA Astrophysics Data System (ADS)

A general summability method, the so-called [theta]-summability is considered for multi-dimensional Fourier transforms and Fourier series. A new inequality for the Hardy-Littlewood maximal function is verified. It is proved that if the Fourier transform of [theta] is in a Herz space, then the restricted maximal operator of the [theta]-means of a distribution is of weak type (1,1), provided that the supremum in the maximal operator is taken over a cone-like set. From this it follows that over a cone-like set a.e. for all . Moreover, converges to f(x) over a cone-like set at each Lebesgue point of if and only if the Fourier transform of [theta] is in a suitable Herz space. These theorems are extended to Wiener amalgam spaces as well. The Riesz and Weierstrass summations are investigated as special cases of the [theta]-summation.

Weisz, Ferenc

2008-08-01

109

Generalised Propagation for Fast Fourier Transforms with Partial or Missing Data  

Microsoft Academic Search

Discrete Fourier transforms and other related Fourier methods have been practically implementable due to the fast Fourier transform (FFT). However there are many situations where doing fast Fourier transforms without complete data would be desirable. In this pa- per it is recognised that formulating the FFT algorithm as a belief network allows suitable priors to be set for the Fourier

Amos J. Storkey

2003-01-01

110

Fourier Transforms of Pulses Containing Exponential Leading and Trailing Profiles  

SciTech Connect

In this monograph we discuss a class of pulse shapes that have exponential rise and fall profiles, and evaluate their Fourier transforms. Such pulses can be used as models for time-varying processes that produce an initial exponential rise and end with the exponential decay of a specified physical quantity. Unipolar examples of such processes include the voltage record of an increasingly rapid charge followed by a damped discharge of a capacitor bank, and the amplitude of an electromagnetic pulse produced by a nuclear explosion. Bipolar examples include acoustic N waves propagating for long distances in the atmosphere that have resulted from explosions in the air, and sonic booms generated by supersonic aircraft. These bipolar pulses have leading and trailing edges that appear to be exponential in character. To the author's knowledge the Fourier transforms of such pulses are not generally well-known or tabulated in Fourier transform compendia, and it is the purpose of this monograph to derive and present these transforms. These Fourier transforms are related to a definite integral of a ratio of exponential functions, whose evaluation we carry out in considerable detail. From this result we derive the Fourier transforms of other related functions. In all Figures showing plots of calculated curves, the actual numbers used for the function parameter values and dependent variables are arbitrary and non-dimensional, and are not identified with any particular physical phenomenon or model.

Warshaw, S I

2001-07-15

111

On the Fourier transform for a symmetric group homogeneous space  

Microsoft Academic Search

By using properties of the Young orthogonal representation, this paper derives a simple form for the Fourier transform of permutations acting on the homogeneous space of $n$-dimensional vectors, and shows that the transform requires $2n-2$ multiplications and the same number of additions.

Ramakrishna Kakarala

2009-01-01

112

Equivalences of Triangulated Categories and Fourier-Mukai Transforms  

Microsoft Academic Search

We give a condition for an exact functor between triangulated categories to\\u000abe an equivalence. Applications to Fourier-Mukai transforms are discussed. In\\u000aparticular, we obtain a large number of such transforms for K3 surfaces.

Tom Bridgeland

1999-01-01

113

[Analysis of cell arrangements in Biota orientalis using Fourier transformation].  

PubMed

Fourier transform image-processing technology is applied for determining the cross section cell arrangement of early-wood in Biota orientalis. In this method, the disc-convoluted dot map from each cell radius with 10 pixels is transformed by Fourier transform, generating the angle distribution function in the power spectral pattern. The maximum value is the arrangement of the cell. The results of Fourier transform image-processing technology indicated that the arrangements of the cell of Biota orientalis are 15 degrees in oblique direction, respectively. This method provides a new basis for the digitized identification of the wood, and also the new theoretical research direction for the digitized identification and examination of the wood species. PMID:20038030

Duo, Hua-Qiong; Wang, Xi-Ming

2009-10-01

114

Fractional Fourier transform of two-dimensional signal with DSP device  

NASA Astrophysics Data System (ADS)

Taking advantage of the high speed arithmetic offers by the parallelism of the digital signal processor DSP TMS320C6711 of TI, we implemented two algorithms to find the Fourier transform of fractional order of two dimensional signals ("The discrete fractional Fourier transform" and "Fractional Fourier Transform calculation through the fast-Fourier-transform algorithm"). As a result, we have two algorithms for calculate the fractional Fourier transform of images using a DSP, the images are captured using a camera CCD and the fractional Fourier transform is display in a monitor, both are connected to the DSP device directly. Finally, the work focuses in the evaluation of this algorithms, in order to find which is best performance related to four criteria determined from the properties of the Fourier transform of fractional order: The inverse transform, fractional Fourier transform of order one or standard Fourier transform, fractional Fourier transform of order zero or operator identity and order additivity.

Cornejo, Joaquin A.; Torres Moreno, Yezid M.

2004-10-01

115

Geometry and dynamics in the fractional discrete Fourier transform  

Microsoft Academic Search

The N×N Fourier matrix is one distinguished element within the group U(N) of all N×N unitary matrices. It has the geometric property of being a fourth root of unity and is close to the dynamics of harmonic oscillators. The dynamical correspondence is exact only in the N-->? contraction limit for the integral Fourier transform and its fractional powers. In the

Kurt Bernardo Wolf; Guillermo Krötzsch

2007-01-01

116

Imaging Fourier transform spectroscopy with multi-aperture telescopes  

Microsoft Academic Search

Fourier spectroscopy can be performed with multi-aperture telescopes by adjusting the optical path difference between apertures. Expressions are given for the measured intensity and the recovered spectrum for a general multi-aperture system. The transfer function of a multi-aperture spectrometer is strikingly different than for a conventional Michelson imaging spectrometer. ©2003 Optical Society of America OCIS codes: (300.6300) Spectroscopy, Fourier transforms;

Samuel T. Thurman; James R. Fienup; R. L. Kendrick

117

Hardware Implementations of Fourier Transform Signal Processing.  

National Technical Information Service (NTIS)

Methods for signal processing using transform techniques are reviewed with the aim of putting these into perspective, clarifying the chief options available to an intending user and indicating how he should choose between them, bearing in mind the constra...

J. B. G. Roberts D. Greenhalgh G. M. Dillard

1980-01-01

118

Discrete wavelet transform implementation in Fourier domain for multidimensional signal  

NASA Astrophysics Data System (ADS)

Wavelet transforms are often calculated by using the Mallat algorithm. In this algorithm, a signal is decomposed by a cascade of filtering and downsampling operations. Computing time can be important but the filtering operations can be speeded up by using fast Fourier transform (FFT)-based convolutions. Since it is necessary to work in the Fourier domain when large filters are used, we present some results of Fourier-based optimization of the sampling operations. Acceleration can be obtained by expressing the samplings in the Fourier domain. The general equations of the down- and upsampling of digital multidimensional signals are given. It is shown that for special cases such as the separable scheme and Feauveau's quincunx scheme, the samplings can be implemented in the Fourier domain. The performance of the implementations is determined by the number of multiplications involved in both FFT- convolution-based and Fourier-based algorithms. This comparison shows that the computational costs are reduced when the proposed implementation is used. The complexity of the algorithm is O(NlogN). By using this Fourier-based method, the use of large filters or infinite impulse response filters in multiresolution analysis becomes manageable in terms of computation costs. Mesh simplification based on multiresolution `detail relevance' images illustrates an application of the implemenentation.

Nicolier, Frederic; Laligant, Olivier; Truchetet, Frederic

2002-07-01

119

Fourier-Transform Microwave Spectroscopy of HCCNSi and NCNSi  

NASA Astrophysics Data System (ADS)

By means of Fourier transform microwave spectroscopy of a supersonic jet, the pure rotational spectra of the silicon-bearing chain molecules silaisocyanoacetylene, HCCNSi, and cyanosilaisocyanide, NCNSi, have been studied for the first time. The molecules were observed in low-current dc discharges through appropriate gas mixtures comprising CH_3CN/SiH_4 and cyanogen/SiH_4 heavily diluted in neon. Spectroscopic searches and identification were based on predictions from high-level quantum-chemical calculations at the CCSD(T) level of theory in combination with large basis sets. Excellent agreement between experimental and calculated molecular parameters is found. In addition to the parent isotopic species, rotational lines of rare isotopologs were also observed. Because of the close relationship of these two species to known astronomical molecules and due to their sizable dipole moments of ?=1.4 D (HCCNSi) and ?=5.4 D (NCNSi) both are plausible targets for future astronomical searches using large radio telescopes.

Thorwirth, S.; Kaiser, R. I.; McCarthy, M. C.; Crabtree, K. N.; Martinez, O., Jr.

2013-06-01

120

Fourier Transform Microwave Spectroscopy of the Hoso Radical  

NASA Astrophysics Data System (ADS)

Molecules closely-related to SO_2 are of considerable interest because of the important role this triatomic or its surrogates play in the atmospheric and combustion chemistry of sulfur-containing compounds. Previous coupled-cluster quantum chemical calculations of the [HSO_2] potential energy surface conclude that a cis-isomer is the ground state, the trans isomer is a transition state, and that a C2v HSO_2 isomer lies considerably higher in energy (˜ 20 kcal/mol). Using Fourier Transform microwave spectroscopy, the rotational spectrum of the cis-HOSO radical has been precisely characterized for the first time by applying a DC discharge to a mixture of water and sulfur dioxide heavily diluted in neon. The fundamental rotational transition was detected near 17 GHz, in good agreement (within ˜ 1%) of the calculated value derived from the equilibrium structure. Microwave-microwave double resonance techniques have been used to extend the dataset to higher frequencies and to provide confirmation of the spectroscopic assignments. D. Binns, and P. Marshall, Journal of Chemical Physics 95, 4940, (1991) B. Napolion, and J. D. Watts, Chemical Physics Letters 421, 562, (2006)

Lattanzi, Valerio; McCarthy, M. C.; Tamassia, Filippo

2011-06-01

121

Dispersive Fourier transformation for fast continuous single-shot measurements  

NASA Astrophysics Data System (ADS)

Dispersive Fourier transformation is an emerging measurement technique that overcomes the speed limitations of traditional optical instruments and enables fast continuous single-shot measurements in optical sensing, spectroscopy and imaging. Using chromatic dispersion, dispersive Fourier transformation maps the spectrum of an optical pulse to a temporal waveform whose intensity mimics the spectrum, thus allowing a single-pixel photodetector to capture the spectrum at a scan rate significantly beyond what is possible with conventional space-domain spectrometers. Over the past decade, this method has brought us a new class of real-time instruments that permit the capture of rare events such as optical rogue waves and rare cancer cells in blood, which would otherwise be missed using conventional instruments. In this Review, we discuss the principle of dispersive Fourier transformation and its implementation across a wide range of diverse applications.

Goda, K.; Jalali, B.

2013-02-01

122

Neural network signature verification using Haar wavelet and Fourier transforms  

NASA Astrophysics Data System (ADS)

This paper discusses the use of neural network's for handwritten signature verification using the Fourier and Haar wavelet transforms as methods of encoding signature images. Results will be presented that discuss a neural network's ability to generalize to unseen signatures using wavelet encoded training data. These results will be discussed with reference to both Backpropagation networks and Cascade-Correlation networks. Backpropagation and Cascade- Correlation networks are used to compare and contrast the generalization ability of Haar wavelet and Fourier transform encoded signature data.

McCormack, Daniel K.; Brown, B. M.; Pedersen, John F.

1993-08-01

123

Fractional Fourier transform in temporal ghost imaging with classical light  

SciTech Connect

We investigate temporal, second-order classical ghost imaging with long, incoherent, scalar plane-wave pulses. We prove that in rather general conditions, the intensity correlation function at the output of the setup is given by the fractional Fourier transform of the temporal object. In special cases, the correlation function is shown to reduce to the ordinary Fourier transform and the temporal image of the object. Effects influencing the visibility and the resolution are considered. This work extends certain known results on spatial ghost imaging into the time domain and could find applications in temporal tomography of pulses.

Setaelae, Tero [Department of Applied Physics, Aalto University, P.O. Box 13500, FI-00076 Aalto (Finland); Shirai, Tomohiro [Photonics Research Institute, National Institute of Advanced Industrial Science and Technology, 1-2-1 Namiki, Tsukuba 305-8564 (Japan); Friberg, Ari T. [Department of Applied Physics, Aalto University, P.O. Box 13500, FI-00076 Aalto (Finland); Department of Physics and Mathematics, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu (Finland)

2010-10-15

124

Extending Fourier transformations to Hamilton's quaternions and Clifford's geometric algebras  

NASA Astrophysics Data System (ADS)

We show how Fourier transformations can be extended to Hamilton's algebra of quaternions. This was initially motivated by applications in nuclear magnetic resonance and electric engineering. Followed by an ever wider range of applications in color image and signal processing. Hamilton's algebra of quaternions is only one example of the larger class of Clifford's geometric algebras, complete algebras encoding a vector space and all its subspace elements. We introduce how Fourier transformations are extended to Clifford algebras and applied in electromagnetism, and in the processing of images, color images, vector field and climate data.

Hitzer, Eckhard

2013-10-01

125

The Theory of Pulsed Fourier Transform Microwave Spectroscopy Carried Out in a Fabry-Perot Cavity  

Microsoft Academic Search

A semiclassical theory has been developed to describe pulsed Fourier transform microwave spectroscopy carried out in a Fabry-Perot cavity. A density matrix formalism is used to study the interaction of a two-level quantum system with a classical standing wave electric field, appropriate for the Fabry-Perot cavity. Equations describing the polarization of, and subsequent emission of radiation by arbitrary distributions of

Edward Joseph Campbell

1981-01-01

126

Infrared Fourier Transform Spectrometry of Gas Chromatography Effluents.  

National Technical Information Service (NTIS)

An evaluation was made of the performance of a computerized Fourier transform infrared spectrometer for the on-line measurement of the infrared spectra of GC effluents. An optimum condition for GCIR analysis was described. Detection limits of a few nanomo...

L. V. Azarraga A. C. McCall

1974-01-01

127

TWO-DIMENSIONAL FOURIER TRANSFORM ANALYSIS OF HELICOPTER FLYOVER NOISE  

Microsoft Academic Search

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

Odilyn L. Santa Maria; F. Farassat; Philip J. Morris

1999-01-01

128

The research of apodization method of Fourier transform spectrometer  

NASA Astrophysics Data System (ADS)

Apodization function is very important to the spectral accuracy in the phase error correction procession of Fourier transform spectrometer. So a novel apodization function and a high efficient phase error correction method are developed in this paper. The short double sided interferogram data and zero-crossing single sided interferogram data are gained by sampling and this data need zero-padding in order to have the same resolution. Then we reconstruct a complex number sequence, which the real part is the data of zero-crossing single sided interferogram and the imaginary part is the data of short double sided interferogram. The complex number sequence multiplied by the new apodization function and then the discrete Fourier transform is used to attain time domain data. We can obtain high precision spectrum based on the conjugate symmetry properties of discrete Fourier transform in the end. The results of experiments and theory analyzing demonstrate that proposed apodization function could suppress sidelobe and decrease the error due to the short double sided interferogram data have been used twice effectively, and the spectral inversion algorithm based on the new apodization function has not need interpolation computing, only has once fourier transform and once apodization, so the efficiency is improved greatly. Theory analysis and experiments shows the method is reasonable and efficient.

Zhang, Peng; Zhang, Zhi-hui; Han, Shun-li

2013-08-01

129

APPLICATION OF FOURIER TRANSFORM SPECTROSCOPY TO AIR POLLUTION PROBLEMS  

EPA Science Inventory

The nature of information that can be retrieved from spectra obtained with Fourier transform spectroscopy is discussed. Nonlinear, least-squares analysis of spectra is capable of retrieving information that is beyond the reach of conventional methods and has improved precision an...

130

An Adaptation of the Fast Fourier Transform for Parallel Processing  

Microsoft Academic Search

A modified version of the Fast Fourier Transform is developed and described. This version is well adapted for use in a special-purpose computer designed for the purpose. It is shown that only three operators are needed. One operator replaces successive pairs of data points by their sums and differences. The second operator performs a fixed permutation which is an ideal

Marshall C. Pease; Menlo Parh

1968-01-01

131

Signal estimation from modified short-time Fourier transform  

Microsoft Academic Search

In this paper, we present an algorithm to estimate a signal from its modified short-time Fourier transform (STFT). This algorithm is computationally simple and is obtained by minimizing the mean squared error between the STFT of the estimated signal and the modified STFT. Using this algorithm, we also develop an iterative algorithm to estimate a signal from its modified STFT

DANIEL W. GRIFFIN; JAE S. LIM

1984-01-01

132

Stable signal and image reconstruction from noisy Fourier transform phase  

Microsoft Academic Search

The problem of reconstruction of finite signals and images from the noisy Fourier transform phase is addressed. The problem is pointed out to be ill-posed with respect to distortion in the phase. Regularizing reconstruction algorithms are proposed that significantly improve estimates of signals or images reconstructed from their noisy phases

Igor Lyuboshenko; Alexander Akhmetshin

1999-01-01

133

Image registration for Fizeau Fourier transform imaging spectroscopy  

Microsoft Academic Search

Fourier transform imaging spectroscopy (FTIS) can be performed with a Fizeau imaging interferometer by recording a series of images with various optical path differences (OPDs) between subapertures of the optical system and postprocessing. The quality of the spectral data is affected by misregistration of the raw image measurements. A Fizeau FTIS system possesses unique degrees of freedom that can be

Samuel T. Thurman; James R. Fienup

2006-01-01

134

Dealiased spectral images from aliased Fizeau Fourier transform spectroscopy measurements  

Microsoft Academic Search

Fizeau Fourier transform imaging spectroscopy (FTIS) is a technique for collecting both spatial and spectral information about an object with a Fizeau imaging interferometer and postprocessing. The technique possesses unconventional imaging properties due to the fact that the system transfer functions, including the imaging and spectral postprocessing operations, are given by cross correlations between subapertures of the optical system, in

Samuel T. Thurman; James R. Fienup

2007-01-01

135

Image registration for Fizeau Fourier transform imaging spectroscopy  

Microsoft Academic Search

Fourier transform imaging spectroscopy (FTIS) can be performed with a Fizeau imaging interferometer by recording a series of images with various optical path differences (OPDs) between subapertures of the optical system and post- processing. The quality of the spectral data is affected by misregistration of the raw image measurements. A Fizeau FTIS system possesses unique degrees of freedom that can

Samuel T. Thurman; James R. Fienup

136

Discrimination of Salmonella enterica serotypes by Fourier transform infrared spectroscopy  

Microsoft Academic Search

Salmonella continues to be an important cause of foodborne infections in humans throughout the world. The precise nature of the infection depends on the specific combination of host and Salmonella serotypes, some of them being highly pathogenic. Fourier transform infrared (FT-IR) spectroscopy together with chemometric techniques were used in this study to discriminate closely related S. enterica serotypes. Intact cells

Ornella Ewa Preisner; José Cardoso Menezes; Raquel Guiomar; Jorge Machado; João Almeida Lopes

137

Absorption mode fourier transform electrostatic linear ion trap mass spectrometry.  

PubMed

In Fourier transform mass spectrometry, it is well-known that plotting the spectrum in absorption mode rather than magnitude mode has several advantages. However, magnitude spectra remain commonplace due to difficulties associated with determining the phase of each frequency at the onset of data acquisition, which is required for generating absorption spectra. The phasing problem for electrostatic traps is much simpler than for Fourier transform ion cyclotron resonance (FTICR) instruments, which greatly simplifies the generation of absorption spectra. Here, we present a simple method for generating absorption spectra from a Fourier transform electrostatic linear ion trap mass spectrometer. The method involves time shifting the data prior to Fourier transformation in order to synchronize the onset of data acquisition with the moment of ion acceleration into the electrostatic trap. Under these conditions, the initial phase of each frequency at the onset of data acquisition is zero. We demonstrate that absorption mode provides a 1.7-fold increase in resolution (full width at half maximum, fwhm) as well as reduced peak tailing. We also discuss methodology that may be applied to unsynchronized data in order to determine the time shift required to generate an absorption spectrum. PMID:23901788

Hilger, Ryan T; Wyss, Phillip J; Santini, Robert E; McLuckey, Scott A

2013-08-15

138

Propagation of uncertainty in a discrete Fourier transform algorithm  

Microsoft Academic Search

The problem of evaluating the uncertainty that characterises discrete Fourier transform output data is dealt with, using a method based on a ‘white box’ theoretical approach. The main sources of uncertainty (quantization, time jitter, microprocessor finite wordlength) are analysed obtaining equations useful to evaluate the uncertainty in both module and phase output values, for any hardware configuration and for any

Giovanni Betta; Consolatina Liguori; Antonio Pietrosanto

2000-01-01

139

Quantitative flash pyrolysis Fourier transform infrared spectroscopy of organic materials  

Microsoft Academic Search

Thermal degradation is a common technique used to investigate the nature of organic materials. However, existing methods for the Fourier transform infrared (FTIR) identification and quantification of volatile products from the thermal degradation of organic materials are limited to the technique of thermogravimetric analysis (TGA)–FTIR, which utilizes relatively low heating rates. However, the thermal degradation products of organic materials are

Richard W. Court; Mark A. Sephton

2009-01-01

140

Fast Fourier Transform Solvers and Preconditioners for Quadratic Spline Collocation  

Microsoft Academic Search

Quadratic Spline Collocation (QSC) methods of optimal order of convergence have been recently developed for the solution of elliptic Partial Differentia l Equations (PDEs). In this paper, linear solvers based on Fast Fourier Transforms (FFT) are developed for the solution of the QSC equations. The complexity of the FFT solvers is , where is the gridsize in one dimension. These

Christina C. Christara; Kit Sun Ng

2000-01-01

141

Inverses of Multivariable Polynomial Matrices by Discrete Fourier Transforms  

Microsoft Academic Search

The problem of the fast computation of the Moore–Penrose and Drazin inverse of a multi-variable polynomial matrix is addressed. The algorithms proposed, use evaluation-interpolation techniques and the Fast Fourier transform. They proved to be faster than other known algorithms. The efficiency of the algorithms is illustrated via randomly generated examples.

S. Vologiannidis; N. P. Karampetakis

2004-01-01

142

Speech encryption based on fast Fourier transform permutation  

Microsoft Academic Search

This paper deals with the permutation of FFT (Fast Fourier Transform) coefficients in a speech encryption system. The scrambling algorithm is based on the permutation of the FFT coefficients and provides a highly secured scrambled signal by permuting a large number of those coefficients. The algorithm for the generation the permutation matrices is explained. This system is useful for a

Shahram Etemadi Borujeni

2000-01-01

143

The interpolated fast Fourier transform: a comparative study  

Microsoft Academic Search

The properties of five interpolating fast Fourier transform (IFFT) methods (IFFT) are studied with respect to their systematic errors and their noise sensitivity, for a monofrequency signal. It is shown that windows with small spectral side lobes do not always result in a better overall performance of the IFFT method and that time-domain estimators can be more efficient than the

J. Schoukens; Rik Pintelon; H. Van Hamme

1992-01-01

144

An ultrafast barcode reader using amplified dispersive Fourier transform  

Microsoft Academic Search

Dispersive Fourier transformation (FT) is a powerful technique in which the spectrum of a pulse is mapped into a time-domain waveform using chromatic dispersion. It replaces a diffraction grating and detector array with a dispersive fiber, single photodetector, and digitizer. This simplifies the system, and more importantly, enables fast real-time spectroscopy . Dispersive FT has also been used for optical

K. Goda; K. Tsia; B. Jalali

2008-01-01

145

Discrete fractional Fourier transform computation by adaptive method  

NASA Astrophysics Data System (ADS)

The continuous fractional Fourier transform (FRFT) can be interpreted as a rotation of a signal in the time-frequency plane and is a powerful tool for analyzing and processing nonstationary signals. Because of the importance of the FRFT, the discrete fractional Fourier transform (DFRFT) has recently become an important issue. We present the computation method for the DFRFT using the adaptive least-mean-square algorithm. First, the DFRFT computation scheme with single angle parameter of the signal block using the adaptive filter system is introduced. Second, considering the transform angles always change in practical applications, the DFRFT computation scheme with adjustable-angle parameter of the signal block using the adaptive filter system is presented. Then we construct two realization structures of the DFRFT computation with simultaneous multiple-angle parameters for each signal block. The proposed computation approaches have the inherent parallel structures, which make them suitable for efficient very large scale integration implementations.

Zhang, Feng; Tao, Ran; Wang, Yue

2013-06-01

146

Improvement for Characteristic of Multirate Discrete Fourier Transform  

NASA Astrophysics Data System (ADS)

Multirate discrete Fourier transform (MR-DFT) has been proposed as one of the DFT algorithms by us. The feature of the MR-DFT is to use only one multiplication for each Fourier coefficient. Therefore the number of multiplications can be decreased comparing with the conventional DFT. In this paper, for applications of the MR-DFT, we consider how the noise affects the estimation performance of the MR-DFT. Then we propose two improved algorithms of the estimation performance, that is, a shifted multirate discrete Fourier transform (SMR-DFT) and a parallel shifted multirate discrete Fourier transform (PSMR-DFT). The SMR-DFT prevents an aliasing of the additive noise by a frequency modulation. The PSMR-DFT performs the parallel processing of the SMR-DFT with different sample points using the periodicity of an input signal. The estimation performances of the proposed algorithms are compared with MR-DFT by the computer simulations. The SMR-DFT could prevent the degradation of the estimation performance of the MR-DFT in the lower components caused by the wide bandwidth noise. Hence its estimation variance could become 0.61 times of the MR-DFT. Furthermore, the PSMR-DFT could improve the estimation variance of the SMR-DFT to 0.46 times. Comparing the number of operations of the proposed algorithms with the MR-DFT, the number of additions has increased, however, the number of multiplications has the same complexity.

Yamamoto, Hiroko; Noguchi, Kentaro; Tadokoro, Yoshiaki

147

Microholography by Numerical Wavefront Reconstruction in the Fourier Transform Geometry.  

NASA Astrophysics Data System (ADS)

New techniques for pulsed holographic microimaging with x-rays and visible light based on the Fourier transform geometry are presented. A charge-coupled device (CCD) is used to record the holographic information. Images are reconstructed numerically by fast Fourier transform (FFT) and by a novel "stigmatic" aberration-free technique. It is shown by numerical simulation that reconstruction by FFT inherently suffers from coma. An innovative design for a Fourier transform x -ray holographic microscope incorporating a metallic microsphere as the reference wave producing element is presented. The design is optimized for use with an x-ray laser source operating in the range lambda~eq43 A; nickel is found to be the best material for the reference sphere in this range. A visible light analog of the x-ray microscope was built and tested yielding an image of Ascaris larva. Two unique visible light Fourier transform holographic microscopes are also presented. The first incorporates a glycerol microdrop reference lens. This microscope was operated at N.A. ~ 0.25 with an argon ion laser at lambda = 514.5 nm. The transverse point spread function of the system was measured to be 1.40 mum, near the theoretical diffraction limit of 1.29 mu m. The second is a design based on a Mach-Zehnder interferometer. This Fourier Mach Zehnder holographic microscope (FMZHM) offers great flexibility and many advantages. The FMZHM was operated at N.A. _sp{~ }{>} 0.25 with lambda = 514.5 nm and yielded many 2-D and 3-D images of biological samples. A study of potential biological applications of visible and x-ray holographic microscopy is also presented.

Haddad, Waleed Sami

148

On scaling properties of fractional Fourier transform and its relation with other transforms  

NASA Astrophysics Data System (ADS)

Several properties of fractional Fourier transform (FRFT) have been studied recently and many are being investigated at present. In this article, scaling property of the FRFT is generalized and some of its applications are suggested. Some extensions of the sampling relations in the FRFT domain are also presented. The issues related to connections between the FRFT and other signal transforms such as scale transform, fractional Mellin transform, and chirp z-transform, are also investigated.

Sharma, K. K.; Joshi, S. D.

2006-01-01

149

Improved fourier transform based on orthogonal carrier processing  

NASA Astrophysics Data System (ADS)

We present a simplified Fourier-transform process, called the orthogonal frequency Fourier transform (OFFT). Conventional divide-and-conquer techniques, such as the fast Fourier transform (FFT), reduce the number of operations in a Fourier transform and simplify at least some of the complex-valued terms (i.e. twiddle factors). The FFT reduces the number of multipliers, which account for much of the chip area and power consumption in digital VLSI design. The OFFT and inverse OFFT exploit orthogonal frequency relationships to replace multiplications with simpler sampling and adding operations. Specifically, the OFFT replaces twiddle factors with step functions, which are superpositions of harmonic sinusoids. The resulting transform is adapted to add samples that are selected relative to at least one periodic step function, thus eliminating all complex multiplications. In phase and quadrature phase OFFT processing may be performed. OFFTs can be combined with pass-band sampling to simultaneously perform filtering, down conversion, and demodulation. Inverse OFFTs combined with pass-band filters can be used to provide up conversion of multi-carrier signals. Since OFFTs are substantially less complex than FFTs, OFFT processing is applicable to digital radio systems where there are considerable constraints on power consumption and chip size. The OFFT is particularly useful for processing multi-carrier transmission protocols in wireless communications, such as Carrier Interferometry, Orthogonal Frequency Division Multiplexing, and Multi-carrier Code Division Multiple Access, which are quickly gaining favor over single-carrier protocols. OFFT algorithms can process a greater number of carriers and provide lower complexity compared to FFTs.

Shattil, Steve J.; Nassar, Carl R.

2002-10-01

150

Purple bacteria and quantum Fourier transform  

Microsoft Academic Search

The LH-II of purple bacteria Rhodospirillum (Rs.) molischianum and Rhodopseudomonas (Rps.) acidophila adopts a highly symmetrical ring shape, with a radius of about 7 nm. In the case of Rps. acidophila the ring has a ninefold symmetry axis, and in LH-II from Rs. molischianum the ring has an eightfold symmetry axis. These rings are found to exibit two bands of

Samir Lipovaca

2007-01-01

151

Analysis of errors in the computation of Fourier coefficients using the arithmetic Fourier transform (AFT) and summation by parts (SBP)  

Microsoft Academic Search

The computational complexity and the effects of quantization and sampling instant errors in the arithmetic Fourier transform (AFT) and the summation by parts discrete Fourier transform (SBP-DFT) algorithms are examined. The relative efficiency of the AFT and SBP-DFT algorithms is demonstrated by comparing the number of multiplications, additions, memory storage locations, and input signal samples as well as the latency

G. F. Boudreaux-Bartels; D. W. Tufts; P. Dhir; G. Sadasiv; G. Fischer

1989-01-01

152

Novel fringe scanning/Fourier transform method of synthetic imaging  

SciTech Connect

We have developed a one-dimensional theory and a computer model for synthetically imaging scenes using a novel fringe scanning/Fourier transform technique. Our method probes a scene using two interfering beams of slightly different frequency. These beams form a moving fringe pattern which scans the scene and resonates with any spatial frequency components having the same spatial frequency as the scanning fringe pattern. A simple, non-imaging detector above the scene observes any scattered radiation from the scene falling onto it. If a resonance occurs between the scanning fringe pattern and the scene, then the scattered radiation will be modulated at the difference frequency between the two probing beams. By changing the spatial period of the fringe pattern and then measuring the amplitude and phase of the modulated radiation that is scattered from the scene, the Fourier amplitudes and phases of the different spatial frequency components making up the scene can be measured. A synthetic image of the scene being probed can be generated from this Fourier amplitude and phase data by taking the inverse Fourier transform of this information. This technique could be used to image objects using light, ultrasonic, or other electromagnetic or acoustic waves.

Crawford, T.M.; Albano, R.K.

1993-08-01

153

Many-impurity effects in Fourier transform scanning tunneling spectroscopy  

NASA Astrophysics Data System (ADS)

Fourier transform scanning tunneling spectroscopy (FTSTS) is a useful technique for extracting details of the momentum-resolved electronic band structure from inhomogeneities in the local density of states due to disorder-related quasiparticle scattering. To a large extent, current understanding of FTSTS is based on models of Friedel oscillations near isolated impurities. Here, a framework for understanding many-impurity effects is developed based on a systematic treatment of the variance ? ?2 (q,?) of the Fourier transformed local density of states ? (q,?) . One important consequence of this work is a demonstration that the poor signal-to-noise ratio inherent in ? (q,?) due to randomness in impurity positions can be eliminated by configuration averaging ? ?2 (q,?) . Furthermore, we develop a diagrammatic perturbation theory for ? ?2 (q,?) and show that an important bulk quantity, the mean-free-path, can be extracted from FTSTS experiments.

Kodra, O.; Atkinson, W. A.

2006-01-01

154

Fast Fourier transform method for shadow moire fringe pattern analysis  

NASA Astrophysics Data System (ADS)

An image system using the shadow moire method for the quantitative inspection of highway pavement surface has been developed. Studies have shown that a single moire image is ordinarily not sufficient to yield complete information about the gradient of a set of contour lines pertaining to a particular area of surface. The pavement surface reconstruction algorithm that has been developed to date uses two moire interferograms of any point on the surface to obtain overlapping information to correctly measure elevation. In this paper, a fast Fourier transform (FFT) method is described which generates accurate surface topographical information from a single interferogram. The fast Fourier transform used in conjunction with the shadow moire technique provides the basis for an automated pavement survey system now under development. This new approach is expected to significantly decrease system hardware and processing time requirements for an automated pavement survey system.

Guralnick, Sidney A.; Suen, Eric S.; Jin, G.

1992-08-01

155

Fourier transform digital holographic adaptive optics imaging system  

PubMed Central

A Fourier transform digital holographic adaptive optics imaging system and its basic principles are proposed. The CCD is put at the exact Fourier transform plane of the pupil of the eye lens. The spherical curvature introduced by the optics except the eye lens itself is eliminated. The CCD is also at image plane of the target. The point-spread function of the system is directly recorded, making it easier to determine the correct guide-star hologram. Also, the light signal will be stronger at the CCD, especially for phase-aberration sensing. Numerical propagation is avoided. The sensor aperture has nothing to do with the resolution and the possibility of using low coherence or incoherent illumination is opened. The system becomes more efficient and flexible. Although it is intended for ophthalmic use, it also shows potential application in microscopy. The robustness and feasibility of this compact system are demonstrated by simulations and experiments using scattering objects.

Liu, Changgeng; Yu, Xiao; Kim, Myung K.

2013-01-01

156

Target Image Enhancement in Radar Imaging Using Fractional Fourier Transform  

NASA Astrophysics Data System (ADS)

This paper presents a new Range-Doppler Algorithm based on Fractional Fourier Transform (RDA-FrFT) to obtain High-Resolution (HR) images for targets in radar imaging. The performance of the proposed RDA-FrFT is compared with the classical RDA algorithm, which is based on the Fast Fourier Transform (FFT). A closed-form expression for the range and azimuth compression of the proposed RDA-FrFT is mathematically derived and analyzed from the HR Synthetic Aperture Radar (SAR) imaging point of view. The proposed RDA-FrFT takes its advantage of the property of the FrFT to resolve chirp signals with high precision. Results show that the proposed RDA-FrFT gives low Peak Side-Lobe (PSL) and Integrated Side-Lobe (ISL) levels in range and azimuth directions for detected targets. HR images are obtained using the proposed RDA-FrFT algorithm.

El-Mashed, M. G.; Dessouky, M. I.; El-Kordy, M.; Zahran, O.; Abd El-Samie, F. E.

2012-03-01

157

Matrix-Vector Based Fast Fourier Transformations on SDR Architectures  

NASA Astrophysics Data System (ADS)

Today Discrete Fourier Transforms (DFTs) are applied in various radio standards based on OFDM (Orthogonal Frequency Division Multiplex). It is important to gain a fast computational speed for the DFT, which is usually achieved by using specialized Fast Fourier Transform (FFT) engines. However, in face of the Software Defined Radio (SDR) development, more general (parallel) processor architectures are often desirable, which are not tailored to FFT computations. Therefore, alternative approaches are required to reduce the complexity of the DFT. Starting from a matrix-vector based description of the FFT idea, we will present different factorizations of the DFT matrix, which allow a reduction of the complexity that lies between the original DFT and the minimum FFT complexity. The computational complexities of these factorizations and their suitability for implementation on different processor architectures are investigated.

He, Y.; Hueske, K.; Götze, J.; Coersmeier, E.

2008-05-01

158

Optical OFDM based on the fractional Fourier transform  

NASA Astrophysics Data System (ADS)

We describe a innovative OFDM scheme based on orthogonal chirped subcarriers, that corresponds to the fractional Fourier transform (FrFT) of the input signal. The FrFT can be electronically implemented with a complexity equivalent to the conventional fast Fourier transform (FFT); on the other hand, the planar device that implements the FrFT in the optical domain is similar to the passive arrayed waveguide grating (AWG) device that performs the FFT. We analyze the spectral efficiency, the peak-to-average power ratio (PAPR) and the frequency offset sensitivity of a FrFT-based optical OFDM system, and make an accurate comparison with the standard FFT-based implementation.

Cincotti, Gabriella

2012-01-01

159

Near IR electro-optic imaging Fourier transform spectrometer  

NASA Astrophysics Data System (ADS)

JPL and BNS Inc. are jointly developing a compact, low mass, Electro-Optic Imaging Fourier Transform Spectrometer (E-O IFTS) for hyperspectral imaging applications [6]. The spectral region of this spectrometer is in the near IR spectral band of 1 - 2.5 ?m (1000 - 4000 cm-1) to allow high-resolution, high-speed hyperspectral imaging applications. The specific applications for NASA"s missions will focus on the measurement of a large number of different atmospheric gases simultaneously in the same airmass. Due to the use of a combination of birefringent phase retarders (YVO4) and multiple achromatic phase switches to achieve phase delay, this spectrometer is capable of hyperspectral measurements similar to that of the conventional Fourier transform spectrometer but without any moving parts. In this paper, the principle of operations, system architecture and recent technical progress will be presented.

Chao, Tien-Hsin; Zhou, Hanying; Xia, Xiaowei; Serati, Steven

2005-03-01

160

Hyperspectral imaging using electro-optic Fourier transform spectrometer  

NASA Astrophysics Data System (ADS)

JPL and BNS Inc. are jointly developing a compact, low mass, Electro-Optic Imaging Fourier Transform Spectrometer (E-O IFTS) for hyperspectral imaging applications. The spectral region of this spectrometer will be 1 - 2.5 ?m (1000 - 4000 cm-1) to allow high-resolution, high-speed hyperspectral imaging applications. The specific applications for NASA's missions will focus on the measurement of a large number of different atmospheric gases simultaneously in the same airmass. Due to the use of a combination of birefringent phase retarders and multiple achromatic phase switches to achieve phase delay, this spectrometer is capable of hyperspectral measurements similar to that of the conventional Fourier transform spectrometer but without any moving parts. In this paper, the principle of operations, system architecture and recent experimental progress will be presented.

Chao, Tien-Hsin; Zhou, Hanying; Xia, Xiaowei; Serati, Steven A.

2004-04-01

161

High performance discrete Fourier transforms on graphics processors  

Microsoft Academic Search

We present novel algorithms for computing discrete Fourier transforms with high performance on GPUs. We present hierarchical, mixed radix FFT algorithms for both power-of-two and non-power-of-two sizes. Our hierarchical FFT algorithms efficiently exploit shared memory on GPUs using a Stockham formulation. We reduce the memory transpose overheads in hierarchical algorithms by combining the transposes into a block-based multi-FFT algorithm. For

Naga K. Govindaraju; Brandon Lloyd; Yuri Dotsenko; Burton Smith; John Manferdelli

2008-01-01

162

High performance discrete Fourier transforms on graphics processors  

Microsoft Academic Search

We present novel algorithms for computing discrete Fourier transforms with high performance on GPUs. We present hierarchical, mixed radix FFT algorithms for both power-of-two and non-power-of-two sizes. Our hierarchical FFT algorithms efficiently exploit shared memory on GPUs using a Stockham formulation. We reduce the memory transpose overheads in hierarchical algorithms by combining the transposes into a block- based multi-FFT algorithm.

Naga K. Govindaraju; Brandon Lloyd; Yuri Dotsenko; Burton Smith; John Manferdelli

2008-01-01

163

Tandem Fourier transform mass spectrometry of large molecules  

Microsoft Academic Search

Fourier-transform mass spectrometry has a number of key advantages, including simultaneous ion detection over a wide mass range, ultra-high resolution, and extensive capabilities for tandem mass spectrometry (MS\\/MS, even MSⁿ). Here, new methods for soft ionization including ²⁵²Cf plasma desorption, 193 nm laser desorption, multiphoton ionization, and electrospray ionization (ESI) are demonstrated to produce abundant molecular ion species from a

1990-01-01

164

Black string entropy and Fourier-Mukai transform  

Microsoft Academic Search

We propose a microscopic description of black strings in F-theory based on string duality and Fourier-Mukai transform. These strings admit several different microscopic descriptions involving D-brane as well as M2 or M5-brane configurations on elliptically fibered Calabi-Yau threefolds. In particular our results can also be interpreted as an asymptotic microstate count for D6-D2-D0 configurations in the limit of large D2-charge

Iosif Bena; Duiliu-Emanuel Diaconescu; Bogdan Florea

2007-01-01

165

Human Colorectal Cancers Display Abnormal FourierTransform Infrared Spectra  

Microsoft Academic Search

Fourier-transform infrared spectroscopy (FT-IR) was applied to the study of tissue sections of human colorectal cancer. Pairs of tissue samples from colorectal cancer and histologically normal mucosa 5-10 cm away from the tumor were obtained from 11 patients who underwent partial colectomy. All cancer specimens displayed abnormal spectra compared with the corresponding normal tissues. These changes involved the phosphate and

Basil Rigas; Susan Morgello; Ira S. Goldman; Patrick T. T. Wong

1990-01-01

166

Eliminating the picket fence effect of the fast Fourier transform  

Microsoft Academic Search

The canonical fast Fourier transform (FFT) is afflicted by the picket fence effect (PFE). This can be ascribed to the simplification caused by viewing non-parametrically. For a periodic signal composed of frequency well-separated tones, a complex formula for retrieving a tone's frequency can be derived in light of the parametric relationship among the FFT spectral lines around each tone's main-lobe.

Yan Feng Li; Kui Fu Chen

2008-01-01

167

Fractional Fourier transform for off-axis elliptical Gaussian beams  

NASA Astrophysics Data System (ADS)

The fractional Fourier transform (FRT) is applied to off-axis elliptical Gaussian beam (EGB). An analytical formula is derived for the FRT of off-axis EGB in terms of the tensor method. The corresponding tensor ABCD law for performing the FRT of off-axis EGB is also obtained. By using the derived formulae, numerical examples are given. The derived formulae provide a convenient way for analyzing and calculating the FRT of off-axis EGB.

Zheng, Chongwei

2006-03-01

168

Fourier transform raman spectroscopy of synthetic and biological calcium phosphates  

Microsoft Academic Search

Fourier-transform (FT) Raman spectroscopy was used to characterize the organic and mineral components of biological and synthetic calcium phosphate minerals. Raman spectroscopy provides information on biological minerals that is complimentary to more widely used infrared methodologies as some infrared-inactive vibrational modes are Raman-active. The application of FT-Raman technology has, for the first time, enabled the problems of high sample fluorescence

G. R. Sauer; W. B. Zunic; J. R. Durig; R. E. Wuthier

1994-01-01

169

The University of Toronto's balloon-borne Fourier transform spectrometer  

Microsoft Academic Search

The University of Toronto s Fourier transform spectrometer U of T FTS derived from a Bomem DA5 Michelson-type interferometer was rebuilt and flown on the Middle Atmosphere Nitrogen TRend Assessment MANTRA high-altitude balloon platform in September 2004 The U of T FTS has a resolution of 0 02 cm -1 a spectral range covering 1200-5000 cm -1 and InSb and

D. Wunch; J. R. Drummond; C. Midwinter; J. R. Taylor; D. Fu; K. A. Walker; C. T. McElroy; K. Strong; P. Bernath; H. Fast

2006-01-01

170

Fractional Fourier transform for a hollow Gaussian beam  

NASA Astrophysics Data System (ADS)

The fractional Fourier transform (FRT) for a hollow Gaussian beam (HGB) is investigated. Based on the definition of FRT in the cylindrical coordinate system, analytical formulae are derived for the FRT for a HGB. By using the derived formulae, the properties of a HGB in the FRT plane are illustrated numerically. The derived formulae provide a convenient way for analyzing and calculating the FRT of a HGB.

Zheng, Chongwei

2006-06-01

171

Flow injection Fourier transform infrared determination of caffeine in coffee  

Microsoft Academic Search

A fully automatized procedure has been developed for the Fourier transform infrared (FT-IR) spectroscopic determination of caffeine in coffee samples. The method involves the on-line extraction of caffeine with CHCl3. Samples, weighed inside empty PTFE cartridges of 0.5 cm internal diameter (i.d.) and 1.5 ml volume, were humidified with four drops of 0.25 M NH3. The cartridge was installed in

Zouhair Bouhsain; Jose M Garrigues; Salvador Garrigues; Miguel de la Guardia

1999-01-01

172

Fractional Fourier transform of truncated elliptical Gaussian beams  

NASA Astrophysics Data System (ADS)

Based on the fact that a hard-edged elliptical aperture can be expanded approximately as a finite sum of complex Gaussian functions in tensor form, an analytical expression for an elliptical Gaussian beam (EGB) truncated by an elliptical aperture and passing through a fractional Fourier transform system is derived by use of vector integration. The approximate analytical results provide more convenience for studying the propagation and transformation of truncated EGBs than the usual way by using the integral formula directly, and the efficiency of numerical calculation is significantly improved.

Du, Xinyue; Zhao, Daomu

2006-12-01

173

A convolution integral for Fourier transforms on the group SL (2, C )  

Microsoft Academic Search

The Fourier transform of a product of two functions onSL(2,C) is expressed as a convolution integral of the Fourier transforms of its factors. With the help of this convolution integral we present the Fourier transform of a polynomially bounded function as a finite linear combination of analytic delta functionals applied to a continuous function on the real line in an

W. Rühl

1968-01-01

174

Wiener amalgams and pointwise summability of Fourier transforms and Fourier series  

NASA Astrophysics Data System (ADS)

This paper provides a fairly general approach to summability questions for multi-dimensional Fourier transforms. It is based on the use of Wiener amalgam spaces W(L_p,?_q)({mathbb R}(d)) , Herz spaces and weighted versions of Feichtinger's algebra and covers a wide range of concrete special cases (20 of them are listed at the end of the paper). It is proved that under some conditions the maximal operator of the theta-means sigma_T(theta) f can be estimated pointwise by the Hardy-Littlewood maximal function. From this it follows that sigma_T(theta) f {->} f a.e. for all fin W(L_1,?_infty)({mathbb R}(d)) , hence fin L_p({mathbb R}(d)) for any 1? p? infty. Moreover, sigma_T(theta) f(x) converges to f(x) at each Lebesgue point of fin L_1({mathbb R}(d)) (resp. fin W(L_1,?_infty)({mathbb R}(d)) ) if and only if the Fourier transform of theta is in a suitable Herz space. In case theta is in a Besov space or in a weighted Feichtinger's algebra or in a Sobolev-type space then the a.e. convergence is obtained. Some sufficient conditions are given for theta to be in the weighted Feichtinger's algebra. The same results are presented for multi-dimensional Fourier series.

Feichtinger, Hans G.; Weisz, Ferenc

2006-05-01

175

Optical and Sonar Image Classification: Wavelet Packet Transform vs Fourier Transform  

Microsoft Academic Search

To develop a noise-insensitive texture classification algorithm for both optical and underwater sidescan sonar images, we study the multichannel texture classifi- cation algorithm that uses the wavelet packet transform and Fourier transform. The approach uses a multilevel dominant eigenvector estimation algorithm and statisti- cal distance measures to combine and select frequency channel features of greater discriminatory power. Consistently better performance

Xiaoou Tang; W. Kenneth Stewart

2000-01-01

176

Wavelets for approximate Fourier transform and data compression  

NASA Astrophysics Data System (ADS)

This dissertation has two parts. In the first part, we develop a wavelet-based fast approximate Fourier transform algorithm. The second part is devoted to the developments of several wavelet-based data compression techniques for image and seismic data. We propose an algorithm that uses the discrete wavelet transform (DWT) as a tool to compute the discrete Fourier transform (DFT). The classical Cooley-Tukey FFT is shown to be a special case of the proposed algorithm when the wavelets in use are trivial. The main advantage of our algorithm is that the good time and frequency localization of wavelets can be exploited to approximate the Fourier transform for many classes of signals, resulting in much less computation. Thus the new algorithm provides an efficient complexity versus accuracy tradeoff. When approximations are allowed, under certain sparsity conditions, the algorithm can achieve linear complexity, i.e. O(N). The proposed algorithm also has built-in noise reduction capability. For waveform and image compression, we propose a novel scheme using the recently developed Burrows-Wheeler transform (BWT). We show that the discrete wavelet transform (DWT) should be used before the Burrows-Wheeler transform to improve the compression performance for many natural signals and images. We demonstrate that the simple concatenation of the DWT and BWT coding performs comparably as the embedded zerotree wavelet (EZW) compression for images. Various techniques that significantly improve the performance of our compression scheme are also discussed. The phase information is crucial for seismic data processing. However, traditional compression schemes do not pay special attention to preserving the phase of the seismic data, resulting in the loss of critical information. We propose a lossy compression method that preserves the phase as much as possible. The method is based on the self-adjusting wavelet transform that adapts to the locations of the significant signal components. The elegant method of embedded zerotree wavelet compression is modified and incorporated into our compression scheme. Our method can be applied to both one dimensional seismic signals and two dimensional seismic images.

Guo, Haitao

177

Schemes for quantum key distribution with higher-order alphabets using single-photon fractional Fourier optics  

NASA Astrophysics Data System (ADS)

We propose generalized quantum key distribution schemes using spatially encoded d -dimensional qudits based on fractional Fourier transform operations. We determine the necessary conditions on the orders of the transforms which ensure a shared secret random key string and briefly discuss the transmission rate and a possible encoding procedure. We also show that the fractional Fourier transform can be used to analyze more general eavesdropping strategies, including an intermediate-basis attack. The error rate and information gain for the intercept-resend and intermediate-basis attacks are briefly analyzed for a particular example. Effects of atmospheric turbulence in a free-space transmission are considered.

Walborn, S. P.; Lemelle, D. S.; Tasca, D. S.; Souto Ribeiro, P. H.

2008-06-01

178

Black string entropy and Fourier-Mukai transform  

NASA Astrophysics Data System (ADS)

We propose a microscopic description of black strings in F-theory based on string duality and Fourier-Mukai transform. These strings admit several different microscopic descriptions involving D-brane as well as M2 or M5-brane configurations on elliptically fibered Calabi-Yau threefolds. In particular our results can also be interpreted as an asymptotic microstate count for D6-D2-D0 configurations in the limit of large D2-charge on the elliptic fiber. The leading behavior of the microstate degeneracy in this limit is shown to agree with the macroscopic entropy formula derived from the black string supergravity solution.

Bena, Iosif; Diaconescu, Duiliu-Emanuel; Florea, Bogdan

2007-04-01

179

Fourier-transform coherent anti-Stokes Raman scattering microscopy.  

PubMed

We report a novel Fourier-transform-based implementation of coherent anti-Stokes Raman scattering (CARS) microscopy. The method employs a single femtosecond laser source and a Michelson interferometer to create two pulse replicas that are fed into a scanning multiphoton microscope. By varying the time delay between the pulses, we time-resolve the CARS signal, permitting easy removal of the nonresonant background while providing high resolution, spectrally resolved images of CARS modes over the laser bandwidth (approximately 1500 cm(-1)). We demonstrate the method by imaging polystyrene beads in solvent. PMID:16496893

Ogilvie, Jennifer P; Beaurepaire, Emmanuel; Alexandrou, Antigoni; Joffre, Manuel

2006-02-15

180

Fractional Fourier transforms of elliptical Hermite-cosh-Gaussian beams  

NASA Astrophysics Data System (ADS)

A new kind of laser beams named the elliptical Hermite-sinusoidal-Gaussian beams (EHSGBs) is introduced and defined by use of tensor method, and the elliptical Hermite-cosh-Gaussian beam (EHChGB) can be regarded as special case of EHSGBs. The fractional Fourier transform (FRFT) is applied to treat the propagation of EHChGBs. An analytical expression for an EHChGB passing through an FRFT system is derived by using vector integration. Some numerical simulations are illustrated for the propagation properties of EHChGBs through FRFT systems.

Du, Xinyue; Zhao, Daomu

2007-06-01

181

Two-dimensional Fourier transform of scaled Dirac delta curves  

NASA Astrophysics Data System (ADS)

We obtain a Fourier transform scaling relation to find analytically, numerically, or experimentally the spectrum of an arbitrary scaled two-dimensional Dirac delta curve from the spectrum of the nonscaled curve. An amplitude factor is derived and given explicitly in terms of the scaling factors and the angle of the forward tangent at each point of the curve about the positive x axis. With the scaling relation we determine the spectrum of an elliptic curve by a circular geometry instead of an elliptical one. The generalization to N-dimensional Dirac delta curves is also included.

Guizar-Sicairos, Manuel; Gutiérrez-Vega, Julio C.

2004-09-01

182

On Application of the Fourier Transform Band Pass Filtering Technique  

NASA Astrophysics Data System (ADS)

In this work theoretical aspects of the Fourier Transform Band Pass Filter (FTBPF) technique are investigated which show that such a procedure is applicable to extraction of irregular monochromatic oscillations with time-varying amplitudes from the analyzed signal data. Considerations concerning the boundary effects occurring in numerical implementation of the FTBPF are included which indicate that the filter transfer function smoothness influences boundary effects magnitude. The possibility of using the studied filtration technique for recognition of elliptical oscillation polarization is envisaged and an estimate of oscillation polarization classification error is derived.

Popi?ski, Waldemar

2009-01-01

183

MIMO OFDM Systems Based on the Optimal Fractional Fourier Transform  

Microsoft Academic Search

Transmission over wireless time-varying channels can lead to inter-carrier interference (ICaI) and inter-cell interference\\u000a (ICeI) in multiple-input multiple-output orthogonal frequency division multiplexing systems. In this paper, it is considered\\u000a that each cell can search respective optimal order chirp basis to replace exponential basis to suppress ICaI, and optimal\\u000a interference restricted combination equalizer based on the Fractional Fourier Transform is proposed

Huiqi Wang; Hong Ma

2010-01-01

184

Fourier transform vibrational circular dichroism of small pharmaceutical molecules  

NASA Astrophysics Data System (ADS)

Fourier transform vibrational circular dichroism (FT-VCD) spectra of the small pharmaceutical molecules propanolol, ibuprofen and naproxen have been measured in the hydrogen stretching and mid-infrared regions to obtain information on solution conformation and to identify markers for absolute configuration determination. Ab initio molecular orbital calculations of low energy conformations, vibrational frequencies and VCD intensities for fragments of the drugs were utilized in interpreting the spectra. Features characteristic of five conformers of propranolol were identified. The weak positive CH stretching VCD signal in ibuprofen and naproxen is characteristic of the S-configuration of the chiral center common to these two analgesics.

Long, Fujin; Freedman, Teresa B.; Nafie, Laurence A.

1998-06-01

185

Fourier transform infrared - attenuated total reflection for wheat grain  

NASA Astrophysics Data System (ADS)

Mid-infrared regions of the spectrum of grain of four Triticum species were analyzed using Fourier transform infrared - attenuated total reflection. Significant variations were noted in the absorbance of all studied taxa over four wavenumber ranges. The principal component analysis supported strong discrimination of the four examined species. The percentage of variation explained by the first two principal component analyses reached 95.04%, including principal components 1-72.16% and 2-22.88%. The applied method supports quick identification of the grains of various hulled species of wheat and it is a useful tool for evaluating the seeds and food products obtained from those cereal species.

Suchowilska, E.; Kandler, W.; Wiwart, M.; Krska, R.

2012-04-01

186

Fourier transform infrared - attenuated total reflection for wheat grain  

NASA Astrophysics Data System (ADS)

Mid-infrared regions of the spectrum of grain of four Triticum species were analyzed using Fourier transform infrared - attenuated total reflection. Significant variations were noted in the absorbance of all studied taxa over four wavenumber ranges. The principal component analysis supported strong discrimination of the four examined species. The percentage of variation explained by the first two principal component analyses reached 95.04%, including principal components 1-72.16% and 2-22.88%. The applied method supports quick identification of the grains of various hulled species of wheat and it is a useful tool for evaluating the seeds and food products obtained from those cereal species.

Suchowilska, E.; Kandler, W.; Wiwart, M.; Krska, R.

2012-04-01

187

Quantification of Collagen Organization Using Fractal Dimensions and Fourier Transforms  

PubMed Central

Summary The structure of the collagen fibers that composes tendon and ligament are disrupted or damaged during injury and healing. Quantification of these changes is traditionally a laborious and subjective task. In this work we apply two automated techniques, Fourier transformation (FFT) and fractal dimension analysis (FA) to quantify the organization of collagen fibrils. Using multi-photon images we show that for healing ligament FA differentiates more clearly between the different time-points during healing. Using scanning electron microcopy images of overstretched tendon we show that combining FFT and FA measures separates the damaged and undamaged groups more clearly than either method individually.

Frisch, Kayt E.; Duenwald-Kuehl, Sarah E.; Lakes, Roderic S.; Vanderby, Ray

2011-01-01

188

Beam profile for the Herschel-SPIRE Fourier transform spectrometer.  

PubMed

One of the instruments on board the Herschel Space Observatory is the Spectral and Photometric Imaging Receiver (SPIRE). SPIRE employs a Fourier transform spectrometer with feed-horn-coupled bolometers to provide imaging spectroscopy. To interpret the resultant spectral images requires knowledge of the wavelength-dependent beam, which in the case of SPIRE is complicated by the use of multimoded feed horns. In this paper we describe a series of observations and the analysis conducted to determine the wavelength dependence of the SPIRE spectrometer beam profile. PMID:23736346

Makiwa, Gibion; Naylor, David A; Ferlet, Marc; Salji, Carl; Swinyard, Bruce; Polehampton, Edward; van der Wiel, Matthijs H D

2013-06-01

189

Selective enhancements in 2D Fourier transform optical spectroscopy with tailored pulse shapes.  

PubMed

Spectral features in two-dimensional Fourier transform optical spectroscopy were selectively enhanced using pulse shapes and sequences designed to amplify specific excited-state resonances. The enhancement was achieved by tailoring a small set of input parameters that control the amplitude and phase profiles of the excitation fields, coherently driving or suppressing selected resonances. The tailored pulse shapes were applied to enhance exciton and biexciton coherences in a semiconductor quantum well. Enhancement of selected resonances was demonstrated even in cases of spectrally overlapping features and complex many-body interactions. Modifications in the 2D spectral line shapes due to the tailored waveforms were calculated using the optical Bloch equations. PMID:23656554

Wen, Patrick; Nelson, Keith A

2013-05-23

190

On integral and finite Fourier transforms of continuous q-Hermite polynomials  

SciTech Connect

We give an overview of the remarkably simple transformation properties of the continuous q-Hermite polynomials H{sub n}(x vertical bar q) of Rogers with respect to the classical Fourier integral transform. The behavior of the q-Hermite polynomials under the finite Fourier transform and an explicit form of the q-extended eigenfunctions of the finite Fourier transform, defined in terms of these polynomials, are also discussed.

Atakishiyeva, M. K. [Universidad Autonoma del Estado de Morelos, Facultad de Ciencias (Mexico); Atakishiyev, N. M., E-mail: natig_atakishiyev@hotmail.co [Universidad Nacional Autonoma de Mexico, Instituto de Matematicas, Unidad Cuernavaca (Mexico)

2009-05-15

191

Generalized convolution and generalized Fourier–Wiener transform on abstract Wiener space  

Microsoft Academic Search

Using the generalized Fourier–Gauss transforms of functionals defined on the complexification of an abstract Wiener space in M.K. Im, U.C. Ji, and Y.J. Park [Relations between the first variation, the convolutions and the generalized Fourier-Gauss transforms, Bull. Korean Math. Soc. (2009), to appear], we study relations between the generalized convolution and the generalized Fourier–Wiener transform of cylinder functions. And we

Man Kyu Im

2010-01-01

192

Broad-band fourier transform quadrupole ion trap mass spectrometry.  

PubMed

Broad-band nondestructive ion detection is achieved in a quadrupole ion trap mass spectrometer by impulsive excitation of a collection of trapped ions of different masses and recording of ion image currents induced on a small detector electrode embedded in but isolated from the adjacent end cap electrode. The image currents are directly measured using a simple differential preamplifier, filter, and amplifier combination and then Fourier analyzed to obtain broad-band frequency domain spectra characteristic of the sample ions. The use of the detector electrode provides a significant reduction in capacitive coupling with the ring electrode. This minimizes coupling of the rf drive signal, which can saturate the front-end stage of the detection circuit and prevent measurement of the relatively weaker ion image currents. Although impulsive excitation is preferred due to its broad-band characteristics and simplicity of use, results are also given for narrow-band ac and broad-band SWIFT (stored wave-form inverse Fourier transform) excitation. Data using argon, acetophenone, and n-butylbenzene show that a resolution of better than 1000 is obtained with a detection bandwidth of 400 kHz. An advantage of nondestructive ion detection is the ability to measure a single-ion population multiple times. This is demonstrated using argon as the sample gas with an average remeasurement efficiency of >90%. Tandem mass spectrometry experiments using a population of acetophenone ions are also shown. PMID:21619266

Soni, M; Frankevich, V; Nappi, M; Santini, R E; Amy, J W; Cooks, R G

1996-10-01

193

Broad-band Fourier transform quadrupole ion trap mass spectrometry  

SciTech Connect

Broad-band nondestructive ion detection is achieved in a quadrupole ion trap mass spectrometer by impulsive excitation of a collection of trapped ions of different masses and recording of ion image currents induced on a small detector electrode embedded in but isolated from the adjacent end cap electrode. The image currents are directly measured using a simple differential preamplifier, filter, and amplifier combination and then Fourier analyzed to obtain broad-band frequency domain spectra characteristic of the sample ions. The use of the detector electrode provides a significant reduction in capacitive coupling with the ring electrode. This minimizes coupling of the rf drive signal, which can saturate the front-end stage of the detection circuit and prevent measurement of the relatively weaker ion image currents. Although impulsive excitation is preferred due to its broad-band characteristics and simplicity of use, results are also given for narrow-band ac and broad-band SWIFT (stored wave-form inverse Fourier transform) excitation. Data using argon, acetophenone, and n-butylbenzene show that a resolution of better than 1000 is obtained with a detection bandwidth of 400 kHz. An advantage of nondestructive ion detection is the ability to measure a single-ion population multiple times. This is demonstrated using argon as the sample gas with an average measurement efficiency of > 90%. 29 refs., 9 figs., 1 tab.

Soni, M.; Frankevich, V.; Nappi, M.; Santini, R.E.; Amy, J.W.; Cooks, R.G. [Purdue Univ., West Lafayette, IN (United States)

1996-10-01

194

Development of galvanostatic Fourier transform electrochemical impedance spectroscopy.  

PubMed

Here, we report development of the galvanostatic Fourier transform electrochemical impedance spectroscopy (FTEIS), which monitors impedance of electrochemical reactions activated by current steps. We first derive relevant relations for potential change upon application of a step current, obtain impedances theoretically from the relations by simulation, and verify them with experimental results. The validity of the galvanostatic FTEIS technique is demonstrated by measuring impedances of a semiconductive silicon wafer using the conventional frequency response analysis (FRA), the potentiostatic FTEIS, and the galvanostatic FTEIS methods, and the results are in excellent agreement with each other. This work is significant in that the galvanostatic FTEIS would allow one to record impedance changes during charge/discharge cycles of secondary batteries and fuel cells as well as electrochemically irreversible systems which may produce noise level chronoamperometric currents by potentiostatic techniques. PMID:23331177

Nam, Kwang-Mo; Shin, Dong-Hyup; Jung, Namchul; Joo, Moon G; Jeon, Sangmin; Park, Su-Moon; Chang, Byoung-Yong

2013-02-04

195

Calibration of the Geostationary Imaging Fourier Transform Spectrometer (GIFTS)  

NASA Astrophysics Data System (ADS)

The NASA New Millennium Program's Geostationary Imaging Fourier Transform Spectrometer (GIFTS) requires highly accurate radiometric and spectral calibration in order to carry out its mission to provide water vapor, wind, temperature, and trace gas profiling from geostationary orbit. A calibration concept has bene developed for the GIFTS Phase A instrument design. The in-flight calibration is performed using views of two on-board blackbody sources along with cold space. A radiometric calibration uncertainty analysis has been developed and used to show that the expected performance for GIFTS exceeds its top level requirement to measure brightness temperature to better than 1 K. For the Phase A GIFTS design, the spectral calibration is established by the highly stable diode laser used as the reference for interferogram sampling, and verified with comparisons to atmospheric calculations.

Best, Fred A.; Revercomb, Henry E.; Bingham, Gail E.; Knuteson, Robert O.; Tobin, David C.; LaPorte, Daniel D.; Smith, William L.

2001-02-01

196

Synthetic polyisoprenes studied by Fourier transform Raman spectroscopy  

NASA Astrophysics Data System (ADS)

Fourier transform Raman spectra are presented for the cis-1,4 and trans-1,4 isomers of polyisoprenes Vibrational intensities are used to determine quantitatively the amounts of each isomer in the microstructure. Improvements over previous work are suggested for the quantitative assessment of 1,4 microstructure. Also, changes in the Raman spectrum due to oxidative degradation show that preferential oxidative degradation for the vinyl-3,4 units occurs. The ? and ? forms of trans-1,4 polyisoprene were studied the ?(C?C) bands resolved were identified 4 cm -1 apart. A study of the copolymerization of methyl methacrylate with isoprene showed that the 1,4 form is the most favoured form produced on copolymerization. Accurate cis-1,4 and trans-1,4 microstructural information could not, however, be determined.

Bunce, S. J.; Edwards, H. G. M.; Johnson, A. F.; Lewis, I. R.; Turner, P. H.

1993-06-01

197

Charge Reversal Fourier Transform Ion Cyclotron Resonance Mass Spectrometry  

NASA Astrophysics Data System (ADS)

We report the first charge reversal experiments performed by tandem-in-time rather than tandem-in-space MS/MS. Precursor odd-electron anions from fullerene C60, and even-electron ions from 2,7-di- tert-butylfluorene-9-carboxylic acid and 3,3'-bicarbazole were converted into positive product ions (-CR+) inside the magnet of a Fourier transform ion cyclotron resonance mass spectrometer. Charge reversal was activated by irradiating precursor ions with high energy electrons or UV photons: the first reported use of those activation methods for charge reversal. We suggest that high energy electrons achieve charge reversal in one step as double electron transfer, whereas UV-activated -CR+ takes place stepwise through two single electron transfers and formally corresponds to a neutralization-reionization (-NR+) experiment.[Figure not available: see fulltext.

Lobodin, Vladislav V.; Savory, Joshua J.; Kaiser, Nathan K.; Dunk, Paul W.; Marshall, Alan G.

2013-02-01

198

Fourier transform microwave spectroscopy of N,N-dimethylacetamide  

NASA Astrophysics Data System (ADS)

The jet-cooled Fourier-transform microwave spectrum of N,N-dimethylacetamide was recorded in the region of 12 24 GHz, and was analyzed to determine rotational constants and nuclear quadrupole coupling constants. Coriolis-like coupling parameters characterizing interaction between internal rotation of methyl groups and the overall rotation were also determined from internal-rotation tunneling splittings of the rotational transitions. The Coriolis-like coupling parameters permitted determination of the barrier heights to internal rotation of the three methyl groups, which were found to be 677, 237, and 183 cm-1 for the C-methyl top, the trans-N-methyl top and the cis-N-methyl top, respectively.

Fujitake, Masaharu; Kubota, Yuji; Ohashi, Nobukimi

2006-03-01

199

Two-dimensional Fourier-transform spectroscopy of potassium vapor  

SciTech Connect

Optical two-dimensional Fourier-transform (2DFT) spectroscopy is used to study the coherent optical response of potassium vapor in a thin transmission cell. Rephasing and nonrephasing spectra of the D{sub 1} and D{sub 2} transitions are obtained and compared to numerical simulations. Non-perturbative calculations using the optical Bloch equations give very good agreement with the experimental peak strengths and line shapes. Nonradiative Raman-like coherences are isolated using a different 2DFT projection. Comparison between the optical and Raman linewidths shows that dephasing is due to partially correlated energy fluctuations. Density-dependent measurements show distortion of 2DFT spectra due to pulse propagation effects.

Dai, X.; Bristow, A. D.; Karaiskaj, D.; Cundiff, S. T. [JILA, University of Colorado and National Institute of Standards and Technology, Boulder, Colorado 80309-0440 (United States)

2010-11-15

200

Fractional Fourier transform of Lorentz-Gauss vortex beams  

NASA Astrophysics Data System (ADS)

An analytical expression for a Lorentz-Gauss vortex beam passing through a fractional Fourier transform (FRFT) system is derived. The influences of the order of the FRFT and the topological charge on the normalized intensity distribution, the phase distribution, and the orbital angular momentum density of a Lorentz-Gauss vortex beam in the FRFT plane are examined. The order of the FRFT controls the beam spot size, the orientation of the beam spot, the spiral direction of the phase distribution, the spatial orientation of the two peaks in the orbital angular momentum density distribution, and the magnitude of the orbital angular momentum density. The increase of the topological charge not only results in the dark-hollow region becoming large, but also brings about detail changes in the beam profile. The spatial orientation of the two peaks in the orbital angular momentum density distribution and the phase distribution also depend on the topological charge.

Zhou, GuoQuan; Wang, XiaoGang; Chu, XiuXiang

2013-08-01

201

Using Fourier transform microwave spectroscopy to detect hazardous air pollutants  

NASA Astrophysics Data System (ADS)

A pulsed-molecular-beam Fabry-Perot cavity Fourier-transform microwave spectrometer developed at NIST has demonstrated sensitivities for many polar gas- phase molecular species in the low parts per million (ppm) to parts per billion (ppb) range. The highest sensitivity is obtained using neon or argon carrier gas but nitrogen or air can also be used, with some loss in sensitivity (up to 100 times) due to the less efficient rotational and vibrational cooling in the molecular beam with diatomic gases. The minimum detectable concentrations for several representative compounds are provided. These include acetaldehyde, acrolein, propionaldhyde, benzaldehyde, p- tolualdehyde, methanol, SO2, propene, methyl t-butyl ether, ethyl t-butyl ether, and others. Considerable attention has been given to making the instrument versatile and user friendly. The instrument is computer controlled using standard GPIB interfaces and several graphical interfaces under the CPLUPLU operating system.

Lovas, F. J.; Pereyra, W.; Suenram, R. D.; Fraser, G. T.; Grabow, J.-U.; Hight Walker, A. R.

1995-05-01

202

Wavenumber scanning-based Fourier transform white-light interferometry.  

PubMed

Fourier transform white-light interferometry recovers the optical path difference of an interferometer by measuring the phase change caused by scanning wavelength. However, the optical spectrum, obtained by wavelength scanning method (?-method), contains a chirp in period. The chirp would induce deviation and decrease the measurement accuracy. An improved method, the wavenumber scanning method (k-method), is proposed and experimentally demonstrated, in which there is no chirp in the optical spectrum. The measurement results using the k-method and the ?-method are compared experimentally. The experimental results show that the standard deviation of the measurement results decreases from 0.015 to 0.004 ?m, when an extrinsic Fabry-Perot interferometer with a cavity length of 387 ?m is interrogated. PMID:22859041

Wang, Zhen; Jiang, Yi

2012-08-01

203

Universal calculation formula and calibration method in Fourier transform profilometry  

SciTech Connect

We propose a universal calculation formula of Fourier transform profilometry and give a strict theoretical analysis about the phase-height mapping relation. As the request on the experimental setup of the universal calculation formula is unconfined, the projector and the camera can be located arbitrarily to get better fringe information, which makes the operation flexible. The phase-height calibration method under the universal condition is proposed, which can avoid measuring the system parameters directly. It makes the system easy to manipulate and improves the measurement velocity. A computer simulation and experiment are conducted to verify its validity. The calculation formula and calibration method have been applied to measure an object of 22.00 mm maximal height. The relative error of the measurement result is only 0.59%. The experimental results prove that the three-dimensional shape of tested objects can be reconstructed exactly by using the calculation formula and calibration method, and the system has better universality.

Wen Yongfu; Li Sikun; Cheng Haobo; Su Xianyu; Zhang Qican

2010-12-01

204

Fourier transform infrared phase shift cavity ring down spectrometer  

NASA Astrophysics Data System (ADS)

We report on our current status towards the development of a prototype Fourier transform infrared phase shift cavity ring down spectrometer (FTIR-PS-CRDS) system under a U.S. EPA SBIR contract. Our system uses the inherent wavelength-dependent modulation imposed by the FTIR on a broadband thermal source for the phase shift measurement. This spectrally-dependent phase shift is proportional to the spectrally-dependent ring down time, which is proportional to the losses of the cavity including those due to molecular absorption. Our approach is a broadband and spectral range enhancement to conventional CRDS which is typically done in the near IR at a single wavelength; at the same time our approach is a sensitivity enhancement to traditional FTIR owing to the long effective path of the resonant cavity. In this paper we present a summary of the theory including performance projections and the design details of the prototype FTIR-PS-CRDS system.

Schundler, Elizabeth; Mansur, David J.; Vaillancourt, Robert; Benedict-Gill, Ryan; Newbry, Scott P.; Engel, James R.; Rentz Dupuis, Julia

2013-05-01

205

Fourier Transform Microwave Laboratory Detection of HSiNH_2  

NASA Astrophysics Data System (ADS)

HSiNH_2 has been detected by means of Fourier Transform Microwave spectroscopy through its fundamental rotational transition (JK_a,K_c=10,1?0 0,0). The molecule was produced in a discharge of a mixture of silane and ammonia heavily diluted in neon in the throat of a pulsed nozzle prior to supersonic expansion. High level ab initio calculations at the CCSD(T) level of theory have guided our laboratory search. The fundamental rotational transition has been detected within 0.1% of the predicted frequency and shows expected hyperfine structure from the presence of the nitrogen nucleus. Confirmation of the assignment is provided by the detection of the same transition for several isotopic species at precisely the expected predicted frequency, with the same hyperfine splitting. Microwave-microwave double-resonance techniques have been used to detect a second rotational transition.

Lattanzi, Valerio; McCarthy, M. C.; Thaddeus, P.; Thorwirth, Sven

2010-06-01

206

Single pulse pressure wave analysis by fast Fourier transformation.  

PubMed

Pressure recordings from 16 patients with normal pressure by hydrocephalus were analysed during controlled intracranial hypertension. Single pulse pressure wave (PPW) analyses were performed on a computer system with programs for automatic computation of mean intracranial pressure (MICP), pulse amplitude (PA), rise time coefficients (RT) and fast Fourier transformation (FFT). We found good correlation between the first harmony, MICP and PA, and between the fifth harmony and RT. The PPW is mainly composed of low-frequency components, but with increasing RT more high-frequency components are present. RT changes as compliance of the brain changes. Therefore the high-frequency components of the FFT may predict changes in the cerebral compliance, although there was no correlation between any of the harmonies and the pressure volume index (PVI). In this investigation PVI was found difficult to perform and evaluate. PMID:2576101

Christensen, L; Børgesen, S E

1989-12-01

207

Process control using fiber optics and Fourier transform infrared spectroscopy  

NASA Astrophysics Data System (ADS)

A process control system has been constructed using optical fibers interfaced to a Fourier transform infrared (FT-IR) spectrometer, to achieve remote spectroscopic analysis of food samples during processing. The multichannel interface accommodates six fibers, allowing the sequential observation of up to six samples. Novel fiber-optic sampling cells have been constructed, including transmission and attenuated total reflectance (ATR) designs. Different fiber types have been evaluated; in particular, plastic clad silica (PCS) and zirconium fluoride fibers. Processes investigated have included the dilution of fruit juice concentrate, and the addition of alcohol to fruit syrup. Suitable algorithms have been written which use the results of spectroscopic measurements to control and monitor the course of each process, by actuating devices such as valves and switches.

Kemsley, E. K.; Wilson, Reginald H.

1992-03-01

208

Fourier Transform Luminescence Spectroscopy of Semiconductor Thin Films and Devices  

SciTech Connect

We have been successful in adapting Fourier transform (FT) Raman accessories and spectrophotometers for sensitive measurements of the photoluminescence (PL) spectra of photovoltaic materials and devices. In many cases, the sensitivity of the FT technique allows rapid room-temperature measurements of weak luminescence spectra that cannot be observed using dispersive PL spectrophotometers. We present here the results of a number of studies of material and device quality obtained using FT-luminescence spectroscopy, including insights into bandgap variations, defect and impurity effects, and relative recombination rates. We also describe our approach to extending the range of the FT-Raman spectrophotometer to cover the region from 11,500 to 3700 cm-1, enabling FT-luminescence measurements to be made from 1.42 to 0.46 eV, and our investigation of FT-PL microspectroscopy.

Webb, J. D.; Keyes, B. M.; Ahrenkiel, R. K.; Wanlass, M. W.; Ramanathan, K.; Gedvilas, L. M.; Olson, M. R.; Dippo, P.; Jones, K. M.

1999-07-12

209

How to tickle spins with a fourier transform NMR spectrometer.  

PubMed

In the long bygone days of continuous-wave nuclear magnetic resonance (NMR) spectroscopy, a selected transition within a multiplet of a high-resolution spectrum could be irradiated by a highly selective continuous-wave (CW) radio-frequency (rf) field with a very weak amplitude ?(2)/(2?)?J. This causes splittings of connected transitions, allowing one to map the connectivities of all transitions within the energy-level diagram of the spin system. Such "tickling" experiments stimulated the invention of two-dimensional spectroscopy, but seem to have been forgotten for nearly 50 years. We show that tickling can readily be achieved in homonuclear systems with Fourier transform spectrometers by applying short pulses in the intervals between the sampling points. Extensions to heteronuclear systems are even more straightforward since they can be carried out using very weak CW rf fields. PMID:23281148

Segawa, Takuya F; Carnevale, Diego; Bodenhausen, Geoffrey

2012-12-23

210

A direct digital synthesis chirped pulse Fourier transform microwave spectrometer  

NASA Astrophysics Data System (ADS)

Chirped pulse Fourier transform microwave (CP-FTMW) spectrometers have become the instrument of choice for acquiring rotational spectra, due to their high sensitivity, fast acquisition rate, and large bandwidth. Here we present the design and capabilities of a recently constructed CP-FTMW spectrometer using direct digital synthesis (DDS) as a new method for chirped pulse generation, through both a suite of extensive microwave characterizations and deep averaging of the 10-14 GHz spectrum of jet-cooled acetone. The use of DDS is more suited for in situ applications of CP-FTMW spectroscopy, as it reduces the size, weight, and power consumption of the chirp generation segment of the spectrometer all by more than an order of magnitude, while matching the performance of traditional designs. The performance of the instrument was further improved by the use of a high speed digitizer with dedicated signal averaging electronics, which facilitates a data acquisition rate of 2.1 kHz.

Finneran, Ian A.; Holland, Daniel B.; Carroll, P. Brandon; Blake, Geoffrey A.

2013-08-01

211

University of Toronto's balloon-borne Fourier transform spectrometer  

NASA Astrophysics Data System (ADS)

A commercial ABB-Bomem DA5 Fourier transform spectrometer (FTS) was refitted with new software and electronics to create a FTS that is appropriate for both ground-based and balloon-based measurements. Nearly all the electronics were replaced, and new control software was written that allows the instrument to run remotely, provides access to all housekeeping information, and permits considerable freedom in data processing approaches. A ``delta'' tracker was used for fine tracking of the sun over a small tracking range, using the main gondola pointing system for coarse azimuth tracking. This facilitated a simple, effective method of instrument integration onto the payload. The new design reduced the mass of the FTS from 90 to 55 kg and reduced the power consumption from 145 to 65 W.

Wunch, Debra; Midwinter, Clive; Drummond, James R.; Thomas McElroy, C.; Bagès, Anne-Flore

2006-09-01

212

Development of an Imaging Fourier Transform Spectrometer for Astronomy  

NASA Astrophysics Data System (ADS)

We present an overview of the past and current development of the Imaging Fourier Transform Spectrometer (IFTS) concept for ground telescopes produced in collaboration between ABB Bomem and Université Laval. This instrument intends to produce spectra of variable resolutions up to R = ?/?? = 10 000 from the near UV to the near IR (350 nm to 900 nm). It is designed to fit the f/8 focus of the Mont Mégantic 1.6m optical telescope in Québec. The large number of spatial elements (> 1 million pixels) is the novel aspect of this FTS design along with innovative metrology system. Heritage from Next Generation Space Telescope (NGST) IFTS concept, Lawrence Livermore National Laboratory (LLNL)- ABB Bomem instrument and commercial ABB Bomem DA series FTS are reviewed. Techniques for accurately servoing the moving mirror alignment to a value smaller than 0.1 arc second and position to sub nanometer value are discussed. Also presented are results from the assembled interferometer sub-system.

Grandmont, Frederic; Drissen, Laurent; Joncas, Gilles

2003-02-01

213

A rheumatoid arthritis study by Fourier transform infrared spectroscopy  

NASA Astrophysics Data System (ADS)

Rheumatoid arthritis is a systemic inflammatory disease of unknown causes and a new methods to identify it in early stages are needed. The main purpose of this work is the biochemical differentiation of sera between normal and RA patients, through the establishment of a statistical method that can be appropriately used for serological analysis. The human sera from 39 healthy donors and 39 rheumatics donors were collected and analyzed by Fourier Transform Infrared Spectroscopy. The results show significant spectral variations with p<0.05 in regions corresponding to protein, lipids and immunoglobulins. The technique of latex particles, coated with human IgG and monoclonal anti-CRP by indirect agglutination known as FR and CRP, was performed to confirm possible false-negative results within the groups, facilitating the statistical interpretation and validation of the technique.

Carvalho, Carolina S.; Silva, Ana Carla A.; Santos, Tatiano J. P. S.; Martin, Airton A.; Dos Santos Fernandes, Ana Célia; Andrade, Luís E.; Raniero, Leandro

2012-02-01

214

The gas phase characterization of perfluorobutyryl chloride, C 3F 7COCl, using chirped pulse Fourier transform microwave spectroscopy  

NASA Astrophysics Data System (ADS)

A chirped pulse Fourier transform microwave spectrometer has been used to record the pure rotational spectrum of perfluorobutyryl chloride seeded in a pulsed supersonic expansion of argon gas. Only one conformer of the title molecule was observed. For the 35Cl species a total of 236 spectral transitions were recorded. Quantum chemical calculations together with the spectral constants obtained indicate that the observed conformer has the CCCCOCl centers contained within the ab plane with a dihedral angle ?CCCO = 0°.

Grubbs, G. S., II; Cooke, S. A.

2009-11-01

215

An Information Retrieval Model Based on Discrete Fourier Transform  

NASA Astrophysics Data System (ADS)

Information Retrieval (IR) systems combine a variety of techniques stemming from logical, vector-space and probabilistic models. This variety of combinations has produced a significant increase in retrieval effectiveness since early 1990s. Nevertheless, the quest for new frameworks has not been less intense than the research in the optimization and experimentation of the most common retrieval models. This paper presents a new framework based on Discrete Fourier Transform (DFT) for IR. Basically, this model represents a query term as a sine curve and a query is the sum of sine curves, thus it acquires an elegant and sound mathematical form. The sinusoidal representation of the query is transformed from the time domain to the frequency domain through DFT. The result of the DFT is a spectrum. Each document of the collection corresponds to a set of filters and the retrieval operation corresponds to filtering the spectrum - for each document the spectrum is filtered and the result is a power. Hence, the documents are ranked by the power of the spectrum such that the more the document decreases the power of the spectrum, the higher the rank of the document. This paper is mainly theoretical and the retrieval algorithm is reported to suggest the feasibility of the proposed model. Some small-scale experiments carried out for testing the effectiveness of the algorithm indicate a performance comparable to the state-of-the-art.

Costa, Alberto; Melucci, Massimo

216

X-ray refractive optics as a Fourier transformer for high resolution diffraction  

NASA Astrophysics Data System (ADS)

Refractive optics is proposed as a Fourier transformer for high resolution X-ray crystal diffraction. Employing refractive lenses the wave transmitted through the object transforms into spatial intensity distribution at its back focal plane according to the Fourier relations. A theoretical consideration of the Fourier transform technique is presented. Two types of samples were studied in Bragg reflection geometry: a grating made of strips of a thin SiO2 film on Si substrate and a grating made by profiling a Si crystal. Rocking curves of Si(111) Bragg reflection and corresponding Fourier patterns were analyzed.

Ershov, P.; Kuznetsov, S.; Snigireva, I.; Yunkin, V.; Goikhman, A.; Snigirev, A.

2013-05-01

217

Transmission line distance relaying using a variable window short-time Fourier transform  

Microsoft Academic Search

This paper presents a new approach for transmission line protection using a variable window short-time Fourier transform known as S-transform. The S-transform (ST) is a time–frequency spectral localization method, similar to short-time Fourier transform (STFT), but with a Gaussian window whose width scales inversely, and whose height scales linearly with the frequency. The change in spectral energy of the ST

S. R. Samantaray; P. K. Dash

2008-01-01

218

Implementation of Chirp Z Discrete Fourier Transform (DFT) on Virtex II FPGA  

Microsoft Academic Search

The application of Fourier results in conversion in representation of a signal in time domain to frequency domain. Hence, it forms an important tool for frequency analysis. With advent of digital computers, we can perform frequency analysis faster and more efficiently. Thus discrete Fourier transform is important for frequency analysis of signal in discrete form.\\u000aDiscrete Fourier Transform (DFT) and

Hariharan Natarajan

2004-01-01

219

Recursive Algorithm for Phase Retrieval in the Fractional Fourier Transform Domain  

Microsoft Academic Search

We first discuss the discrete fractional Fourier transform and present some essential properties. We then propose a recursive algorithm to implement phase retrieval from two intensities in the fractional Fourier transform domain. This approach can significantly simplify computational manipulations and does not need an initial phase estimate compared with conventional iterative algorithms. Simulation results show that this approach can successfully

Wen-Xiang Cong; Nan-Xian Chen; Ben-Yuan Gu

1998-01-01

220

Algorithms for Reconstruction of Partially Known, Band Limited Fourier Transform Pairs from Noisy Data.  

National Technical Information Service (NTIS)

This paper is a summary of more detailed mathematical work by the author on recovery of partially know Fourier transforms. These problems of inversion of the finite Fourier transform and of phase retrieval are known to be ill-posed. We draw a distinction ...

R. Barakat

1984-01-01

221

Enhanced Optical Image Verification Based on Joint Transform Correlator Adopting Fourier Hologram  

Microsoft Academic Search

In this paper two new architectures for optical image verification are proposed. Both architectures are based on conventional joint transform correlators (JTCs) adopting a Fourier hologram and can significantly improve the recovered image quality. First, an input phase-only function is Fourier transformed and then interferes with a reference wave that is diffracted from a plane wave incident on another random

Hsuan T. CHANGand; Ching T. T. Chen

2004-01-01

222

Architecture of the fast Walsh-Hadamard and fast Fourier transforms with charge transfer devices  

Microsoft Academic Search

This paper presents a novel approach for charge transfer device (CTD) implementation of the fast Walsh-Hadamard and fast Fourier transforms. This is achieved by first expressing the Hadamard matrix as a power of a matrix, which allows for efficient CTD implementation. These results are then used in CTD implementation of fast Fourier transforms. The errors which accrue on using CTDs

RAO YARLAGADDA; JOHN E. HERSHEY

1981-01-01

223

Application of the two-dimensional Fourier transform to nonlinear wave propagation phenomena  

Microsoft Academic Search

A new technique based on the two-dimensional Fourier transform is presented and applied to the study of nonlinear wave propagation phenomena in one-dimensional, finite, nonlinear transmission lines. The technique permits determining the effects of nonlinearities and boundary conditions on the Fourier transform and identifying incident and reflected waves and solitons which may propagate through the transmission line at constant speed.

I. Molina-Fernandez; C. Camacho-Penalosa; Juan I. Ramos

1994-01-01

224

Transformative effects of higher magnetic field in Fourier transform ion cyclotron mass spectrometry  

PubMed Central

The relationship of magnetic field strength and Fourier transform ion cyclotron resonance mass spectrometry performance was tested using three instruments with the same designs but different fields of 4.7, 7 and 9.4 tesla. We found that the theoretically predicted “transformative” effects of magnetic field are indeed observed experimentally. The most striking effects were that mass accuracy demonstrated approximately 2nd–3rd-order improvement with the magnetic field, depending upon the charge state of the analyte, and that peak splitting, which prohibited automated data analysis at 4.7 T, was not observed at 9.4 T.

Karabacak, N. Murat; Easterling, Michael L.; Agar, N.Y.R.; Agar, Jeffrey N.

2010-01-01

225

Cryogenic Fourier transform infrared spectrometer from 4 to 20 micrometers  

NASA Astrophysics Data System (ADS)

We describe the design and performance of a cryogenic Fourier transform spectrometer (Cryo-FTS) operating at a temperature of approximately 15 K. The instrument is based on a porch-swing scanning mirror design with active alignment stabilization using a fiber-optic coupled diode laser and voice-coil actuator mechanism. It has a KBr beamsplitter and has been integrated into an infrared radiometer containing a calibrated Si:As blocked impurity band (BIB) detector. Due to its low operating temperature, the spectrometer exhibits very small thermal background signal and low drift. Data from tests of basic spectrometer function, such as modulation efficiency, scan jitter, spectral range, and spectral resolution are presented. We also present results from measurements of faint point-like sources in a low background environment, including background, signal offset and gain, and spectral noise equivalent power, and discuss the possible use of the instrument for spectral characterization of ground-based infrared astronomy calibration sources. The Cryo-FTS is presently limited to wavelengths below 25 micrometers but can be in principle extended to longer wavelengths with changes in beamsplitter and detector.

Kaplan, Simon G.; Woods, Solomon I.; Jung, Timothy M.; Carter, Adriaan C.

2010-07-01

226

Fourier Transform Power Spectra Analysis of Dwarf Irregular Galaxies  

NASA Astrophysics Data System (ADS)

The LITTLE THINGS survey has obtained deep HI emission line maps with the data from VLA B, C and D array configurations for a representative sample of nearby dwarf irregular galaxies, and supplemented this with images from the FUV to the NIR. We present the fourier transform power spectra of the HI maps, FUV and NIR images for a subsample of nearly face-on (minor-to-major axis ratio > 0.8) LITTLE THINGS galaxies in order to examine structures within the galaxies' gas and stellar disks.The radial variations of the power spectra will be compared with global properties. We will also compare the relationship between the gas, star formation and stellar mass on different physical scales and at different radii, and discuss the possibility of using breaks in power-law power spectra to constrain the disk thickness. The LITTLE THINGS team is grateful to the National Science Foundation for funding through grants AST-0707563, AST-0707426, AST-0707468, and AST-0707835 to DAH, BGE, CES, and LMY. HZ was partly supported by NSF of China through grants \\#10425313, \\#10833006 and \\#10621303 to Professor Yu Gao.

Zhang, Hongxin; Hunter, D. A.; LITTLE THINGS Team

2012-01-01

227

Remote detection of organics using Fourier transform infrared spectroscopy  

SciTech Connect

Fourier transform infrared (FTIR) spectroscopy is an ideal technique for remote detection of organic emissions. There is an atmospheric window in the 1200 to 800 cm{sup {minus}1} region, which corresponds to the fingerprint'' region for organic molecules. Virtually all organic molecules have a unique absorption/emission pattern in the fingerprint region. A remote-passive FTIR relies on ambient emission of infrared energy from organics to obtain spectra. The instrumentation consists of inlet optics, and interferometer, a mercury cadmium telluride (MCT) detector, and an on-board computer. The transportable unit measures 40 cm by 50 cm and has been used to collect data while mounted on a helicopter or ground vehicle. Through the use of this FTIR combined with least squares software, it is possible to analyze qualitatively and quantitatively for organic vapors from either the air or ground. The data presented will include quantitative releases of common organics present in incinerator stacks, hazardous wastes, and illegal laboratories. Data will be presented for pure compounds, mixtures, and target analytes in the presence of interfering compounds. The sensitivity, reproducibility, and the potential of the technique will be discussed. 1 ref., 8 figs., 6 tabs.

Demirgian, J.C.; Spurgash, S.M.

1990-01-01

228

Fourier transform infrared spectroscopic analysis of cell differentiation  

NASA Astrophysics Data System (ADS)

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.

Ishii, Katsunori; Kimura, Akinori; Kushibiki, Toshihiro; Awazu, Kunio

2007-03-01

229

ABR topographic mapping with digital filtering using fast Fourier transform.  

PubMed

The power spectrum of normal ABR consists of three major parts: low (0-350 Hz: component A), middle (350-700 Hz: component B) and high (700-1200 Hz: component C) frequency components. With digital filtering using fast Fourier transform (FFT), three component waveforms of ABR were obtained and designated as component A, B and C. Component A has a positive peak which corresponds to wave V or the slow component of the original ABR. Component B has three positive peaks (B1-B3) which correspond to wave I, III and V, and component C has five positive peaks (C1-C5) which correspond to wave I-V. These three component waveforms of ABR were analyzed topographically in normal hearing adults and cats. In addition, changes in the topography of three component waveforms of ABR were studied in a series of experimentally induced lesions in the brainstem auditory pathway in cats. The following results were obtained: i) The highest voltage (HV) area of component B1 was detected on the ipsilateral side in normal adults and cats. The HV areas of component C1, C2 and C3 in normal adults and C1, C2 in normal cats were detected on the ipsilateral side. ii) There was a correlation between changes in component C and the lesion site of the auditory pathway. Component C appears to be the most sensitive indicator of the lesion site of the brainstem. PMID:8203245

Suzuki, T; Aoyagi, M; Koike, Y

1994-01-01

230

Analysis of ovarian tumor pathology by Fourier Transform Infrared Spectroscopy  

PubMed Central

Background Ovarian cancer is the second most common cancer among women and the leading cause of death among gynecologic malignancies. In recent years, infrared (IR) spectroscopy has gained attention as a simple and inexpensive method for the biomedical study of several diseases. In the present study infrared spectra of normal and malignant ovarian tissues were recorded in the 650 cm-1 to 4000 cm-1 region. Methods Post surgical tissue samples were taken from the normal and tumor sections of the tissue. Fourier Transform Infrared (FTIR) data on twelve cases of ovarian cancer with different grades of malignancy from patients of different age groups were analyzed. Results Significant spectral differences between the normal and the ovarian cancerous tissues were observed. In particular changes in frequency and intensity in the spectral region of protein, nucleic acid and lipid vibrational modes were observed. It was evident that the sample-to-sample or patient-to-patient variations were small and the spectral differences between normal and diseased tissues were reproducible. Conclusion The measured spectroscopic features, which are the spectroscopic fingerprints of the tissues, provided the important differentiating information about the malignant and normal tissues. The findings of this study demonstrate the possible use of infrared spectroscopy in differentiating normal and malignant ovarian tissues.

2010-01-01

231

Fundamental performances of a micro stationary Fourier transform spectrometer  

NASA Astrophysics Data System (ADS)

A new configuration of micro-spectrometer based on an infrared stationary Fourier transform (FTIR) interferometer has been developed at ONERA. Our device is based on a classic infrared focal plane array (FPA) of HgCdTe technology with a built-in two-wave wedge-like interferometer. This new architecture generates research works in several domains. Technological researches are conducted in collaboration with the CEA to optimize the manufacturing process and reduce the technological defects. In parallel, researches in optical design are conducted to implement the FTIR-FPA in a complete system. For this, theoretical work is needed to understand and describe the fringes formation inside the detection structure when illuminated by a wave which is not ideal, i.e. emitted by an extended source positioned at a finite distance from the detection plane. The results of this theoretical study are presented. These results are exploited to design a compact spectrometer with a very simple optical architecture. First experimental data are presented and discussed.

Gillard, Frédéric; Guérineau, Nicolas; Rommeluère, Sylvain; Taboury, Jean; Chavel, Pierre

2010-04-01

232

Fourier Transform Emission Spectroscopy of CuCl.  

PubMed

The electronic spectra of CuCl were observed in the 18 000 cm(-1) to 25 000 cm(-1) spectral region using a Bruker IFS 120 HR Fourier transform spectrometer (FTS) and with the FTS associated with the McMath-Pierce Solar Telescope at Kitt Peak. On the basis of ab initio calculations, the labels for the electronic states were revised, and the a(3)Sigma(+)(1)-X(1)Sigma(+) 0-0 band, the b(3)Pi(0)-X(1)Sigma(+) 0-0, 1-0, and 0-1 bands, the b(3)Pi(1)-X(1)Sigma(+) 0-0, 1-0, and 0-1 bands, the A(1)Pi-X(1)Sigma(+) 0-0, 1-0, and 0-2 bands, and the B(1)Sigma(+)-X(1)Sigma(+) 0-0 and 1-0 bands were measured. Improved spectroscopic constants were obtained for the excited and ground states. Copyright 2001 Academic Press. PMID:11281681

Parekunnel, T.; O'Brien, L. C.; Kellerman, T. L.; Hirao, T.; Elhanine, M.; Bernath, P. F.

2001-03-01

233

Fourier transform infrared and physicochemical analyses of roasted coffee.  

PubMed

In this study, Brazilian coffee beans processed to different stages of roast at 210, 220, 230, and 240 °C were analyzed for pH value, titratable acidity, moisture content, and color lightness. Fourier transform infrared (FTIR) spectroscopy, in conjunction with principal component analysis, was conducted to study the effects of process time and temperature on the IR-active components of the acetyl acetate extract of the roasted coffee. The results showed that high-temperature-short-time resulted in higher moisture content, higher pH value, and higher titratable acidity when the beans were roasted beyond the start-of-second-crack stage, as compare to low-temperature-long-time process (LTLT). The LTLT process also resulted in greater IR absorbance for aldehydes, ketones, aliphatic acids, aromatic acids, and caffeine carbonyl bands on the FTIR spectra. Clusters for principal component score plots were well separated, indicating that the changes IR-active components in the coffee extracts, due to the different roasting treatments, can be discriminated by the FTIR technique. On the basis of the loading plots of principal components, changes of IR-active compounds in the coffee extract at various stages of roasting were discussed. PMID:22563854

Wang, Niya; Lim, Loong-Tak

2012-05-16

234

Quantitative flash pyrolysis Fourier transform infrared spectroscopy of organic materials.  

PubMed

Thermal degradation is a common technique used to investigate the nature of organic materials. However, existing methods for the Fourier transform infrared (FTIR) identification and quantification of volatile products from the thermal degradation of organic materials are limited to the technique of thermogravimetric analysis (TGA)-FTIR, which utilizes relatively low heating rates. However, the thermal degradation products of organic materials are known to vary depending on the rate of heating, with lower heating rates of biomass associated with increased yields of solid char and decreased yields of volatiles, as well as a greater opportunity for secondary reactions between the residue and the pyrolysis products. Hence, it is difficult to relate the products of organic matter thermally degraded at <100 degrees C min(-1) in TGA to the products of flash pyrolysis at up to 20,000 degrees C s(-1). We have developed and applied a novel methodology for quantitative flash pyrolysis-FTIR analysis of the volatile pyrolysis products of organic-rich materials. Calibration curves of water, carbon dioxide and methane have been constructed and used to determine absolute volatile release from wood (ash, Lat. Fraxinus). This technique is quicker and simpler than comparable pyrolysis-gas chromatography-mass spectrometry techniques, and avoids errors associated with the lower rates of temperature increase associated with techniques such as thermogravimetric analysis. PMID:19345759

Court, Richard W; Sephton, Mark A

2009-03-06

235

Fourier-transform Raman characterization of brazilwood trees and substitutes.  

PubMed

In this work we have applied Fourier-transform Raman spectroscopy to the analysis of several archival samples of brazilwoods from different geographical origins and of different ages. Samples of Caesalpinia echinata Lam. (from Brazil, South America), Caesalpinia sappan L. (East Indies, Asia), Haematoxylum brasiletto Karsten (Central America) and Haematoxylum campechianum L. (North America) were analysed in order to isolate key Raman biomarker bands which could provide the basis for an identification protocol. Previously recorded Raman spectra of brazilin and brazilein pigments extracted from genuine brazilwood of Brazilian origin provided a foundation for the nondestructive spectral discrimination between a sample of false 'brazilwood', which consisted of an inferior wood substratum stained with genuine pigment, and the true specimens. The provision of well-documented specimens of determinable age from the archival collection facilitated the evaluation of the effects of temporal degradation on the observed spectra, which could be used to further test the experimental protocols for nondestructive verification of samples in the archive with questionable assignment or provenance. PMID:12572809

Edwards, Howell G M; de Oliveira, Luiz F C; Nesbitt, Mark

2003-01-01

236

Fourier transform infrared spectroscopy (FTIR) of laser-irradiated cementum  

NASA Astrophysics Data System (ADS)

Utilizing Fourier Transform Infrared Spectroscopy (FTIR) in specular reflectance mode chemical changes of root cement surfaces due to laser radiation were investigated. A total of 18 samples of root cement were analyzed, six served as controls. In this study laser energies were set to those known for removal of calculus or for disinfection of periodontal pockets. Major changes in organic as well as inorganic components of the cementum were observed following Nd:YAG laser irradiation (wavelength 1064 nm, pulse duration 250 ?s, free running, pulse repetition rate 20 Hz, fiber diameter 320 ?m, contact mode; Iskra Twinlight, Fontona, Slovenia). Er:YAG laser irradiation (wavelength 2.94 ?m, pulse duration 250 ?s, free running, pulse repetition rate 6 Hz, focus diameter 620 ?m, air water cooling 30 ml/min; Iskra Twinlight, Fontona, Slovenia) significantly reduced the Amid bands due to changes in the organic components. After irradiation with a frequency doubled Alexandrite laser (wavelength 377 nm, pulse duration 200 ns, q-switched, pulse repetition rate 20 Hz, beam diameter 800 ?m, contact mode, water cooling 30 ml/min; laboratory prototype) only minimal reductions in the peak intensity of the Amide-II band were detected.

Rechmann, Peter; White, Joel M.; Cecchini, Silvia C. M.; Hennig, Thomas

2003-06-01

237

Fourier transform microwave spectroscopy of aluminum hydrosulfide, AlSH  

NASA Astrophysics Data System (ADS)

Pure rotational transitions of three isotopic species of aluminum hydrosulfide, AlSH, have been measured with a cavity pulsed jet Fourier transform microwave spectrometer. AlSH was prepared by the reaction of laser ablated Al metal with H2S, and was stabilized in pulsed supersonic free jets of Ar. For each species the transition 101-000 was measured; hyperfine structure due to the nuclear spin of 27Al was observed for the first time and analyzed. For Al32SH and Al32SD, the rotational constants are in excellent agreement with published values. For the third species, Al34SH, this is the first observation, and its rotational constants are consistent with the published geometry. Information on the electronic structure of the molecule has been obtained using the 27Al nuclear quadrupole coupling constants and nuclear spin-rotation constants. The latter have been used to evaluate 27Al NMR shielding parameters, which are compared with those of other 27Al compounds. These shieldings have been found to be in excellent agreement with theoretical predictions. The results should also help facilitate astrophysical searches for the molecule.

Fukushima, Masaru; Gerry, Michael C. L.

2010-07-01

238

Vehicle Recognition Based on Fourier, Wavelet and Curvelet Transforms - a Comparative Study  

Microsoft Academic Search

Summary This paper proposes the application of 3 different kinds of feature extractors to recognize & classify 5 models of vehicles. These feature extractors are Fast Fourier transform, discrete wavelet transform & discrete curvelet transform. To justify the correct amount of each feature extractor, we perform each of the mentioned transforms to input images, precisely. The classifier used in this

Farhad Mohamad Kazemi; Saeed Samadi; Hamid Reza Pourreza; Mohammad R. Akbarzadeh-totonchi

2007-01-01

239

Correspondence between quantum-optical transform and classical-optical transform explored by developing Dirac's symbolic method  

NASA Astrophysics Data System (ADS)

By virtue of the new technique of performing integration over Dirac's ket-bra operators, we explore quantum optical version of classical optical transformations such as optical Fresnel transform, Hankel transform, fractional Fourier transform, Wigner transform, wavelet transform and Fresnel-Hadmard combinatorial transform etc. In this way one may gain benefit for developing classical optics theory from the research in quantum optics, or vice-versa. We cannot only find some new quantum mechanical unitary operators which correspond to the known optical transformations, deriving a new theorem for calculating quantum tomogram of density operators, but also can reveal some new classical optical transformations. For examples, we find the generalized Fresnel operator (GFO) to correspond to the generalized Fresnel transform (GFT) in classical optics. We derive GFO's normal product form and its canonical coherent state representation and find that GFO is the loyal representation of symplectic group multiplication rule. We show that GFT is just the transformation matrix element of GFO in the coordinate representation such that two successive GFTs is still a GFT. The ABCD rule of the Gaussian beam propagation is directly demonstrated in the context of quantum optics. Especially, the introduction of quantum mechanical entangled state representations opens up a new area in finding new classical optical transformations. The complex wavelet transform and the condition of mother wavelet are studied in the context of quantum optics too. Throughout our discussions, the coherent state, the entangled state representation of the two-mode squeezing operators and the technique of integration within an ordered product (IWOP) of operators are fully used. All these have confirmed Dirac's assertion: "...for a quantum dynamic system that has a classical analogue, unitary transformation in the quantum theory is the analogue of contact transformation in the classical theory".

Fan, Hong-yi; Hu, Li-yun

2012-06-01

240

Far infrared Fourier-transform spectroscopy of mono-deuterated hydrogen peroxide HOOD  

NASA Astrophysics Data System (ADS)

We present the gas phase spectrum of singly deuterated hydrogen peroxide, HOOD, in its vibrational ground state, recorded by the high resolution Fourier-transform interferometer located at the AILES synchrotron beamline connected to SOLEIL. More than 1000 transitions in the range from 20 to 143 cm?1 were assigned, leading to a set of preliminary rotational and centrifugal distortion constants determined by least squares fit analysis. All transitions are split by the tunneling motion of a hindered internal rotation. The splitting has been determined to be 5.786(13) cm?1 in the torsional ground state and it shows a dependence on the rotational quantum number Ka. Some perturbations were not treated yet, but the present analysis permits to obtain a preliminary set of parameters.

Herberth, Doris; Baum, Oliver; Pirali, Olivier; Roy, Pascale; Thorwirth, Sven; Yamada, Koichi M. T.; Schlemmer, Stephan; Giesen, Thomas F.

2012-07-01

241

Optical Doppler tomography with short-time Fourier transform and Hilbert transform  

NASA Astrophysics Data System (ADS)

Optical Doppler tomography (ODT) combines Doppler principle with Optical coherence tomography (OCT) to image both the structure and the flow velocity of moving particles in highly scattering biological tissues. The flow velocity can be determined by measurement of the Doppler shift of the interference fringe frequency with a short-time Fourier transform (STFT) or a Hilbert transform. For STFT ODT, velocity resolution varies inversely with the Fourier transform window size at each pixel, while spatial resolution is proportional to the window size. Consequently, velocity resolution and spatial resolution are coupled. For phase-resolved ODT with Hilbert transform, high velocity resolution can be achieved while maintaining a high spatial resolution. However, the maximum determinable Doppler shift is limited by axial-line scanning speed. As a result, STFT ODT and phase-resolved ODT are applicable to measurement of high speed and low speed velocity, respectively. We use these two methods in the established ODT system. An in vitro model using a small circular glass tubule with flowing solution of polystyrene beads inside and an in vivo model of rat's cerebral arterioles are investigated, demonstrating the advantage and disadvantage of STFT ODT and phase-resolved ODT.

Meng, Jie; Ding, Zhihua

2007-10-01

242

Millimeter/submillimeter Fourier Transform Spectroscopy of Jovian Planet Atmospheres  

NASA Astrophysics Data System (ADS)

A new Fourier transform spectrometer, built for use at the Caltech Submillimeter Observatory, has been used to observe all four of the jovian planets (Jupiter, Saturn, Uranus, and Neptune) in the millimeter-submillimeter wavelength range (0.3-3.0 mm). These observations have resulted in the detection of the PH_3 1-0 rotational line (266.9 GHz) in Saturn, and the PH _3 3-2 (800.5 GHz) line in both Jupiter and Saturn. Because PH_3 is a disequilibrium species, it is an important tracer of vertical mixing and upper atmospheric photochemistry, and can therefore be used to derive dynamical and chemical properties of the jovian atmospheres. A jovian planet radiative transfer code has been used to model the observed PH_3 lineshapes. Using the FTS, a spectral line survey covering the entire range of submillimeter frequencies observable from the ground has also been performed on Jupiter at Saturn at a resolution of 200 MHz. This survey has yielded the tentative detection of HCl (and possibly HCN) in Saturn and, again with the aid of radiative transfer modeling, provided a great number of improved upper limits on the concentrations of many other species. Finally, Uranus and Neptune have been observed in the 1300 ?m atmospheric window which contains the CO 2-1 transition. This line was not detected in either planet, placing upper limits on the tropospheric CO mole fraction of 0.5 ppm in Uranus and 1.4 ppm in Neptune. A new Fourier transform spectrometer, built for use at the Caltech Submillimeter Observatory, has been used to observe all four of the jovian planets (Jupiter, Saturn, Uranus, and Neptune) in the millimeter-submillimeter wavelength range (0.3-3.0 mm). These observations have resulted in the detection of the PH_3 1-0 rotational line (266.9 GHz) in Saturn, and the PH _3 3-2 (800.5 GHz) line in both Jupiter and Saturn. Because PH_3 is a disequilibrium species, it is an important tracer of vertical mixing and upper atmospheric photochemistry, and can therefore be used to derive dynamical and chemical properties of the jovian atmospheres. A jovian planet radiative transfer code has been used to model the observed PH_3 lineshapes. Using the FTS, a spectral line survey covering the entire range of submillimeter frequencies observable from the ground has also been performed on Jupiter at Saturn at a resolution of 200 MHz. This survey has yielded the tentative detection of HCl (and possibly HCN) in Saturn and, again with the aid of radiative transfer modeling, provided a great number of improved upper limits on the concentrations of many other species. Finally, Uranus and Neptune have been observed in the 1300 ?m atmospheric window which contains the CO 2-1 transition. This line was not detected in either planet, placing upper limits on the tropospheric CO mole fraction of 0.5 ppm in Uranus and 1.4 ppm in Neptune.

Weisstein, Eric Wolfgang

1996-01-01

243

Dual Comb Fourier Transform Spectroscopy in the Green Region  

NASA Astrophysics Data System (ADS)

Laser combs in combination with other advancing tools of laser science, nonlinear optics, photonics, and electronic signal processing have the potential to vastly enhance the range and capabilities of molecular laser spectroscopy. The high versatility of frequency comb sources can indeed harness new techniques for ultra-rapid and ultra-sensitive recording of complex molecular spectra. The recent proof-of-principle demonstrations of dual comb Fourier transform spectroscopy have mostly been carried out in the near-infrared region, around 1.0 and 1.5 ?m. The mode-locked ytterbium- or erbium-doped fiber femtosecond laser systems emitting in this range indeed require few adjustment thanks to their guided light and permit reliable unattended operation. With expanded wavelength coverage and continued improvements in speed and sensitivity, dual comb spectroscopy should find use as a novel, time-domain spectroscopic analytical tool. As far as molecular spectroscopy is concerned, the mid-infrared and visible-ultraviolet wavelength regions show both the potential for specificity and sensitivity for tracing molecules. In particular, the visible-ultraviolet region complements the mid-infrared molecular fingerprint range, as it provides access to many electronic transitions, in particular belonging to reactive species. In this contribution, we report on our progress in the implementation of dual comb spectroscopy in the 520 nm green region. We present preliminary results on a powerful new sensitive ultra-rapid tool for linear rovibronic absorption spectroscopy, based on frequency-doubled ytterbium-doped fiber lasers and we discuss its intriguing prospects for spectroscopy of short lived transient species.

Knize, R. J.; Bernhardt, B.; Picqué, N.; Hänsch, T. W.

2010-06-01

244

IFIRS: an Imaging Fourier Transform Spectrometer for NGST  

NASA Astrophysics Data System (ADS)

To accomplish the scientific objectives of NGST, the observatory must be equipped with instruments suitable for panchromatic observations across the 1-15 mu m spectral region on the faintest detectable objects. A wide-field imaging spectrometer that is efficient in the confusion limit, which may occur in deep field images, will maximize the scientific return and opportunities for serendipity from NGST. An imaging Fourier transform spectrometer (IFTS) supports these requirements in a low-cost, efficient instrument package that functions as an electronically programmable infrared filter with both imaging and spectroscopic capability. The conceptual design of the Integral Field Infrared Spectrograph (IFIRS) is an imaging FTS configured as a 4-port Michelson interferometer. The added ports are obtained by the use of cube-corner retroreflectors. A 4-port design delivers complementary symmetric and antisymmetric interferograms to the primary and secondary focal plane assemblies (FPAs). In this design, the object field of the complementary input is also imaged and superimposed on each image of the primary input. In operation, when observing the sky in the primary input, the secondary input would be fed with a cold blackbody having negligible radiance. The final interferogram is constructed from the difference between the two outputs (which is therefore also immune to common mode noise) while the normalized ratio of the difference to the sum of the two outputs serves to compensate for temporal variations in the object radiance, and may reveal systematic variations due to telescope throughput or detector drifts. The interferometer aperture, field angle, beam waist control, beamsplitter/beamcombiner co-planar alignment, maximum optical frequency and maximum resolution have been traded at a conceptual level of detail. These tradeoffs suggest that a 12 cm beam splitter diameter is sufficient to accept the throughput of an 8 m primary over a 3.'4 x 3.'4 square field of view.

Graham, J. R.; Macoy, N. H.; Wickham, D. R.; Hertel, R. J.; Abrams, M. C.; Bennett, C. L.; Cook, K. H.; Wurtz, R.; Carr, J.; Dey, A.; Najita, J. R.; Morris, S. L.; Villemaire, A.; Wishnow, E.

1998-12-01

245

IFIRS: an Imaging Fourier Transform Spectrometer for NGST  

NASA Astrophysics Data System (ADS)

To accomplish the scientific objectives of NGST, the observatory must be equipped with instruments suitable for panchromatic observations across the 1-15 mu m spectral region on the faintest detectable objects. A wide-field imaging spectrometer that is efficient in the confusion limit, which may occur in deep field images, will maximize the scientific return and opportunities for serendipity from NGST. An imaging Fourier transform spectrometer (IFTS) supports these requirements in a low-cost, efficient instrument package that functions as an electronically programmable infrared filter with both imaging and spectroscopic capability. The conceptual design of the Integral Field Infrared Spectrograph (IFIRS) is an imaging FTS configured as a 4-port Michelson interferometer. The added ports are obtained by the use of cube-corner retroreflectors. A 4-port design delivers complementary symmetric and antisymmetric interferograms to the primary and secondary focal plane assemblies (FPAs). In this design, the object field of the complementary input is also imaged and superimposed on each image of the primary input. In operation, when observing the sky in the primary input, the secondary input would be fed with a cold blackbody having negligible radiance. The final interferogram is constructed from the difference between the two outputs (which is therefore also immune to common mode noise) while the normalized ratio of the difference to the sum of the two outputs serves to compensate for temporal variations in the object radiance, and may reveal systematic variations due to telescope throughput or detector drifts. The interferometer aperture, field angle, beam waist control, beamsplitter/beamcombiner co-planar alignment, maximum optical frequency and maximum resolution have been traded at a conceptual level of detail. These tradeoffs suggest that a 12 cm beam splitter diameter is sufficient to accept the throughput of an 8 m primary over a 5.'3 x 5.'3 square field of view.

Graham, J. R.; Macoy, N. H.; Wickham, D. R.; Hertel, R. J.; Abrams, M. C.; Bennett, C. L.; Cook, K.; Wurtz, R.; Carr, J.; Dey, A.; Najita, J.; Morris, S.; Villemaire, A.; Wishnow, E.

1999-05-01

246

Quantum computation of multifractal exponents through the quantum wavelet transform  

SciTech Connect

We study the use of the quantum wavelet transform to extract efficiently information about the multifractal exponents for multifractal quantum states. We show that, combined with quantum simulation algorithms, it enables to build quantum algorithms for multifractal exponents with a polynomial gain compared to classical simulations. Numerical results indicate that a rough estimate of fractality could be obtained exponentially fast. Our findings are relevant, e.g., for quantum simulations of multifractal quantum maps and of the Anderson model at the metal-insulator transition.

Garcia-Mata, Ignacio; Giraud, Olivier; Georgeot, Bertrand [Laboratoire de Physique Theorique (IRSAMC), UPS, Universite de Toulouse, F-31062 Toulouse (France); LPT - IRSAMC, CNRS, F-31062 Toulouse (France)

2009-05-15

247

Comparison of Fourier transform, windowed Fourier transform, and wavelet transform methods for phase calculation at discontinuities in fringe projection pro?lometry  

NASA Astrophysics Data System (ADS)

Phase demodulation techniques from one fringe pattern have been widely studied because it can measure dynamic objects by capturing single image. These techniques mainly include Fourier transform (FT), windowed Fourier transform (WFT), and wavelet transform (WT). FT has been widely used to demodulate phase information from single deformed fringe pattern on smooth objects. However, for objects having discontinuities and/or large slopes, FT cannot obtain correct phase at the edges because of its global processing. WFT and WT have been applied to nonstationary fringe pattern analysis. Since local fringe information used to extract phase information, WFT and WT are better than FT for phase calculation at discontinuities and/or slopes. In this paper, we discuss the pro and con of the three methods on phase calculation at discontinuities and/or slopes. Simulated and experimental data are tested at edges in order to confirm which method is appropriate to measure objects having discontinuities by using one-frame fringe pattern acquisition method.

Zhang, Zonghua; Jing, Zhao; Wang, Zhaohui; Kuang, Dengfeng

2012-08-01

248

The Fourier-series method for inverting transforms of probability distributions  

Microsoft Academic Search

This paper reviews the Fourier-series method for calculating cumulative distribution functions (cdf's) and probability mass functions (pmf's) by numerically inverting characteristic functions, Laplace transforms and generating functions. Some variants of the Fourier-series method are remarkably easy to use, requiring programs of less than fifty lines. The Fourier-series method can be interpreted as numerically integrating a standard inversion integral by means

Joseph Abate; Ward Whitt

1992-01-01

249

Two-Dimensional Fourier Transform Analysis of Helicopter Flyover Noise.  

National Technical Information Service (NTIS)

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...

P. J. Morris

2004-01-01

250

Two-Dimensional Fourier Transform Analysis of Helicopter Flyover Noise.  

National Technical Information Service (NTIS)

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...

O. L. SantaMaria F. Farassat P. J. Morris

1999-01-01

251

Fourier-transform-based composite intelligent control for high-frequency-response voice coil motor  

Microsoft Academic Search

During to the non derivability for triangle wave reference trajectory, whose high-frequency harmonics will stimulate the resonant modes in the high-frequency voice coil motor (VCM), the traditional speed and acceleration feed forwards can not be achieved. In this paper, the triangle wave was Fourier transformed to get its Fourier series composed of several sine functions, which are high order differential.

Xuanju Dang; Silin Zeng; Lin Zhang

2010-01-01

252

Lensless Fourier transform holography with soft x-rays  

NASA Astrophysics Data System (ADS)

Soft x-rays are effective for viewing nanoscale systems with element-specific contrast. Observations of these systems at sub-picosecond time scales are limited by the currently available x-ray sources, but this will change as x-ray free electron lasers come online. Capturing ultrafast images on the nanoscale at these x-ray sources will require techniques that are compatible with coherent, ultrafast, high-intensity x-ray pulses. Fourier transform holography (FTH) is one such technique. The developments in lensless soft x-ray FTH that make it a practical technique for single shot imaging are presented in this dissertation. FTH is robust, versatile and well suited for imaging with high spatial resolution. The key to realizing these attributes is the integration of a nanoscale transmission mask with the sample. The mask, which defines the holographic object and reference beams, is fabricated by focused ion beam milling. The advantages of using the integrated mask were first demonstrated by imaging a non-periodic magnetic worm domain pattern with 50 nm spatial resolution. This demonstration of spectro-holography used x-ray magnetic circular dichroism to capture a high contrast lensless image of the ferromagnetic domain structure in a magnetic multilayer film. A set of four follow-on experiments have developed the single shot capabilities of FTH. (1) Spatial multiplexing is introduced to extend the effective field of view without compromising spatial resolution. (2) By combining the extended field of view with a cross-beam pump-probe geometry, a method is proposed for imaging ultrafast evolution in a single shot. (3) Multiple reference sources are used experimentally to improve the signal-to-noise ratio of an image without increasing the exposure to the sample. (4) The capability of FTH to simultaneously access both phase and absorption contrast is observed. Without a laser like source of coherent x-rays, these experiments used high brilliance synchrotron radiation from undulator beamlines on electron storage rings, namely SSRL at SLAC and BESSY in Germany. The new instrumentation and methods developed here are relevant and transferable to the forthcoming x-ray free electron laser sources.

Schlotter, William F.

253

Rapid Bacterial Identification Using Fourier Transform Infrared Spectroscopy  

SciTech Connect

Recent studies at Pacific Northwest National Laboratory (PNNL) using infrared spectroscopy combined with statistical analysis have shown the ability to identify and discriminate vegetative bacteria, bacterial spores and background interferents from one another. Since the anthrax releases in 2001, rapid identification of unknown powders has become a necessity. Bacterial endospores are formed by some Bacillus species as a result of the vegetative bacteria undergoing environmental stress, e.g. a lack of nutrients. Endospores are formed as a survival mechanism and are extremely resistant to heat, cold, sunlight and some chemicals. They become airborne easily and are thus readily dispersed which was demonstrated in the Hart building. Fourier Transform Infrared (FTIR) spectroscopy is one of several rapid analytical methods used for bacterial endospore identification. The most common means of bacterial identification is culturing, but this is a time-consuming process, taking hours to days. It is difficult to rapidly identify potentially harmful bacterial agents in a highly reproducible way. Various analytical methods, including FTIR, Raman, photoacoustic FTIR and Matrix Assisted Laser Desorption/Ionization (MALDI) have been used to identify vegetative bacteria and bacterial endospores. Each has shown certain areas of promise, but each has shortcomings in terms of sensitivity, measurement time or portability. IR spectroscopy has been successfully used to distinguish between the sporulated and vegetative state. [1,2] It has also shown its utility at distinguishing between the spores of different species. [2-4] There are several Bacillus species that occur commonly in nature, so it is important to be able to distinguish between the many different species versus those that present an imminent health threat. The spectra of the different sporulated species are all quite similar, though there are some subtle yet reproducible spectroscopic differences. Thus, a more robust and reliable method is needed for differentiation. Using chemometrics, a classification scheme was developed and performed on samples sporulated in glucose broth. PNNL has demonstrated that vegetative bacteria and endospores have unique infrared (IR) signatures that can be used to identify to the species-, and in some cases, even to the strain-level. We have shown that the IR spectra of spores of different species tend to be quite similar, yet the small but reproducible differences in the spectra allow for a certain degree of differentiation. Further studies have shown that the culture medium can also have an effect on the spectra. For the distinction between vegetative and endospores, we have consistently observed a series of four peaks at 766, 725, 702, and a fairly sharp peak (FWHM 7 cm-1) at 660 cm-1, present only in the endospore spectra.

Valentine, Nancy B.; Johnson, Timothy J.; Su, Yin-Fong; Forrester, Joel B.

2007-02-01

254

Multiple Internal Reflection Fourier Transform Infrared Spectroscopy Studies of Thiocyanate Adsorption on Silver and Gold.  

National Technical Information Service (NTIS)

Conducting silver and gold coatings on silicon Attenuated Total Reflectance (ATR) plates have been employed as transparent electrodes to monitor in situ surface electrochemistry. The multiple internal reflection Fourier transform infrared spectroscopy (MI...

D. B. Parry J. M. Harris K. Ashley

1989-01-01

255

Applications of Fourier Transform Infrared Photoacoustic Spectroscopy to Solid Propellant Characterization.  

National Technical Information Service (NTIS)

Fourier transform infrared photoacoustic spectroscopy (FT-IR-PAS) has been used to examine surfaces of composite solid propellants. Depletion of crystalline energetic material from extruded surfaces and of plasticizer from aged surfaces has been documente...

R. A. Fifer R. A. Pesce-Rodriguez

1991-01-01

256

HIGH SENSITIVITY FOURIER TRANSFORM NMR. INTERMOLECULAR INTERACTIONS BETWEEN ENVIRONMENTAL TOXIC SUBSTANCES AND BIOLOGICAL MACROMOLECULES  

EPA Science Inventory

This project explored the feasibility of developing new techniques for evaluation of the effects of environmental toxic materials on complex biopolymer systems using high sensitivity Fourier transform nuclear magnetic resonance (nmr) spectroscopy. Commercial instrumentation avail...

257

Characterisation of optical pulses travelling through a photonic crystal fibre using Fourier-transform spectral interferometry  

NASA Astrophysics Data System (ADS)

Dispersion properties of a 37 cm long photonic crystal fibre were studied using spectral interferometry. The interferograms were evaluated by the conventional and the windowed Fourier-transform method, as well as other commonly used ones, such as the cosine function fit, the stationary phase point and the minima-maxima methods. It is shown that from the five techniques the conventional Fourier-transform method provided the dispersion coefficients with the highest accuracy, and both Fourier-transform techniques could detect phase jumps in the vicinity of the absorption valleys seen in the transmission spectrum of the fibre. We present a novel simple evaluation procedure based on Fouriertransform for a quick retrieval of the spatial and temporal pulse shape after the fibre. The time delay between the higher and the fundamental transversal modes was also measured by the Fourier-transform method.

Grósz, T.; Kiss, M.; Kovács, A. P.

2013-05-01

258

MATRIX MATERIALS FOR DIFFUSE REFLECTANCE FOURIER TRANSFORM INFRARED SPECTROMETRY OF SUBSTANCES IN POLAR SOLVENTS  

EPA Science Inventory

Calcium floride, magnesium fluoride, sulfur, silver bromide, silver chloride, and five different particle sizes of diamond powder were studied for use as matrix materials for diffuse reflectance Fourier transform infrared spectrometry. Potassium chloride was used as a reference b...

259

Investigation of Distortion of Divers' Speech Using Power Spectral Estimates Based on the Fast Fourier Transform.  

National Technical Information Service (NTIS)

The problem of distortion in underwater communications peculiar to free divers and techniques for analysis of speech wave forms are discussed. The fast Fourier transform algorithm, selected to analyze shifts in formant frequencies due to restricted oral c...

W. H. Bond J. M. Myatt

1969-01-01

260

Discrete Fourier Transform Identities for Testing the Accuracy of Digital Data Processing Systems and Procedures.  

National Technical Information Service (NTIS)

Analytical expressions are developed for the discrete Fourier transforms (DFTs) of three classes of theoretical time series that often occur in physical and engineering investigations. The DFTs are expressed in terms of arbitrary parameters specifying the...

R. A. Saenger

1974-01-01

261

Photoselective discrimination of matrix isolated respiratory enzymes from E. coli by Fourier transform infrared spectroscopy  

NASA Astrophysics Data System (ADS)

Photodissociation of heme-CO complexes in bacterial membranes was measured by Fourier transform infrared spectroscopy. Wavelength of the photodissociating light and selected cryogenic temperatures were used to distinguish multiple forms of respiratory enzymes (cytochromes).

Hill, John J.; Gennis, R. B.; Alben, James O.

1992-03-01

262

The Fourier Transform in Chemistry. Part 1. Nuclear Magnetic Resonance: Introduction.  

ERIC Educational Resources Information Center

|Using fourier transformation methods in nuclear magnetic resonance has made possible increased sensitivity in chemical analysis. This article describes these methods as they relate to magnetization, the RF magnetic field, nuclear relaxation, the RF pulse, and free induction decay. (CW)|

King, Roy W.; Williams, Kathryn R.

1989-01-01

263

Effect of coherence and polarization on frequency resolution in optical Fourier transforming system.  

PubMed

Using an example of vector Gaussian Schell-model beam, we demonstrate and analyze the dependence of the spatial frequency resolution in optical Fourier transforming system on the intrinsic coherence-polarization structure of illumination. PMID:22139295

Ostrovsky, Andrey S; Olvera-Santamaría, Miguel Á; Romero-Soría, Paulo C

2011-12-01

264

Particulate Matter Measurements using Open-Path Fourier Transform Infrared Spectroscopy.  

National Technical Information Service (NTIS)

Open-path Fourier transform infrared (OP-FTIR) spectroscopy is an accepted technology for measuring gaseous air contaminants. OP-FTIR absorbance spectra acquired during changing aerosols conditions reveal related changes in very broad baseline features. U...

R. A. Hashmonay D. B. Harris

2001-01-01

265

Polarized fourier transform infrared microscopy as a tool for structural analysis of adsorbates in molecular sieves  

SciTech Connect

This report tries to determine whether polarized fourier transform infrared microscopy could be useful in the analysis of the adsorbate structure in zeolites. Measurements on p-xylene loaded single crystals of silicalite I were performed.

Schueth, F. [Gutenberg-Universitaet, Mainz (Germany)

1992-09-17

266

A Pulsar de-dispersion Algorithm Based on the Short Time Fourier Transform (STFT)  

Microsoft Academic Search

In this paper a pulsar de-dispersion algorithm based on the Short Time Fourier Transform (STFT) is presented. First of all, the reason of the pulsar dispersion and several popular de-dispersion algorithms are induced. Secondly, the Short Time Fourier Transform (STFT) algorithm is also introduced and a de-dispersion algorithm is proposed based on it. Thirdly, the process of this algorithm is

Jian-Jian Gao; Cheng-Jin Jin; Long Gao

2007-01-01

267

Improved space time prewhitener for linear frequency modulation reverberation using fractional Fourier transform.  

PubMed

This letter presents an improved space time prewhitening method for linear frequency modulation (LFM) reverberation. The proposed method transforms the reverberation to fractional Fourier domain to whiten using fractional Fourier transform. The linear varying frequency in LFM reverberation is focused on a stationary frequency, and the adjacent block signal is used as the reference signal of prewhitening. Finally, experiment results with real reverberation data verify that the proposed method improves the detection performance of active sonar in shallow sea significantly. PMID:21218858

Wang, Ruhang; Huang, Jianguo; Ma, Tian; Zhang, Qunfei

2010-12-01

268

Phase retrieval from the magnitude of the Fourier transforms of nonperiodic objects  

Microsoft Academic Search

It is suggested that, given the magnitude of Fourier transforms sampled at the Bragg density, the phase problem is underdetermined by a factor of 2 for 1D, 2D, and 3D objects. It is therefore unnecessary to oversample the magnitude of Fourier transforms by 2Ã in each dimension (i.e., oversampling by 4Ã for 2D and 8Ã for 3D) in retrieving the

J. Miao; D. Sayre; H. N. Chapman

1998-01-01

269

Three-Dimensional X-Ray Fourier Transform Holography: The Bragg Case  

NASA Astrophysics Data System (ADS)

A novel approach to determine the structure of nanoscale crystals in three dimensions is proposed by the use of coherent x-ray Fourier transform holography in Bragg geometry. The full internal description is directly obtained by a single Fourier transform of the 3D intensity hologram. Together with the morphology, Bragg geometry gives access to the 3D displacement field within the crystal. This result opens great possibilities for the investigation of strain fields inside nanocrystals in a simple way.

Chamard, V.; Stangl, J.; Carbone, G.; Diaz, A.; Chen, G.; Alfonso, C.; Mocuta, C.; Metzger, T. H.

2010-04-01

270

Alternative path to the boundary: The CFT as the Fourier transform in AdS space  

SciTech Connect

In this paper we shed new light on the AdS/CFT duality by interpreting the CFT as the Fourier transform in AdS space. We make use of well-known integral geometry techniques to derive the Fourier transformation of a function defined on the AdS hyperboloid. We show that the Fourier transformation of a function on the hyperboloid is a function defined on the boundary. We find that the Green's functions from the literature are actually the Fourier weights (i.e. plane wave solutions) of the transformation and that the boundary values of fields appearing in the correspondence are the Fourier components of the transformation. One is thus left to interpret the CFT as the quantized version of a classical theory in AdS and the dual operator as the Fourier coefficients. Group theoretic considerations are discussed in relation to the transformation and its potential use in constructing QCD-like theories. In addition, we consider possible implications involving understanding the dual of AdS black holes.

Tolfree, Ian M. [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218 (United States)

2008-11-15

271

Alternative path to the boundary: The CFT as the Fourier transform in AdS space  

NASA Astrophysics Data System (ADS)

In this paper we shed new light on the AdS/CFT duality by interpreting the CFT as the Fourier transform in AdS space. We make use of well-known integral geometry techniques to derive the Fourier transformation of a function defined on the AdS hyperboloid. We show that the Fourier transformation of a function on the hyperboloid is a function defined on the boundary. We find that the Green’s functions from the literature are actually the Fourier weights (i.e. plane wave solutions) of the transformation and that the boundary values of fields appearing in the correspondence are the Fourier components of the transformation. One is thus left to interpret the CFT as the quantized version of a classical theory in AdS and the dual operator as the Fourier coefficients. Group theoretic considerations are discussed in relation to the transformation and its potential use in constructing QCD-like theories. In addition, we consider possible implications involving understanding the dual of AdS black holes.

Tolfree, Ian M.

2008-11-01

272

A program transformation and architecture support for quantum uncomputation  

Microsoft Academic Search

Quantum computing's power comes from new algorithms that exploit quantum mechanical phenomena for computation. Quantum algorithms are different from their classical counterparts in that quantum algorithms rely on algorithmic structures that are simply not present in classical computing. Just as classical program transformations and architectures have been designed for common classical algorithm structures, quantum program transformations and quantum architectures should

Ethan Schuchman; T. N. Vijaykumar

2006-01-01

273

Quantum simulation of noncausal kinematic transformations.  

PubMed

We propose the implementation of Galileo group symmetry operations or, in general, linear coordinate transformations in a quantum simulator. With an appropriate encoding, unitary gates applied to our quantum system give rise to Galilean boosts or spatial and time parity operations in the simulated dynamics. This framework provides us with a flexible toolbox that enhances the versatility of quantum simulation theory, allowing the direct access to dynamical quantities that would otherwise require full tomography. Furthermore, this method enables the study of noncausal kinematics and phenomena beyond special relativity in a quantum controllable system. PMID:24033011

Alvarez-Rodriguez, U; Casanova, J; Lamata, L; Solano, E

2013-08-28

274

Quantum Simulation of Noncausal Kinematic Transformations  

NASA Astrophysics Data System (ADS)

We propose the implementation of Galileo group symmetry operations or, in general, linear coordinate transformations in a quantum simulator. With an appropriate encoding, unitary gates applied to our quantum system give rise to Galilean boosts or spatial and time parity operations in the simulated dynamics. This framework provides us with a flexible toolbox that enhances the versatility of quantum simulation theory, allowing the direct access to dynamical quantities that would otherwise require full tomography. Furthermore, this method enables the study of noncausal kinematics and phenomena beyond special relativity in a quantum controllable system.

Alvarez-Rodriguez, U.; Casanova, J.; Lamata, L.; Solano, E.

2013-08-01

275

FourierTransform Method of Phase-Shift Determination  

Microsoft Academic Search

A new phase-shifting interferometry analysis technique has been developed to overcome the errors introduced by nonlinear, irregular, or unknown phase-step increments. In the presence of a spatial carrier frequency, by observation of the phase of the first-order maximum in the Fourier domain, the global phase-step positions can be measured, phase-shifting elements can be calibrated, and the accuracy of phase-shifting analysis

Kenneth A. Goldberg; Jeffrey Bokor

2001-01-01

276

Dynamic measurements by color gratings projection method using a two-step Fourier transform method  

NASA Astrophysics Data System (ADS)

The Fourier transform method is an analytical method for interferograms with a spatial linear carrier. Interferograms with a spatial linear carrier are analyzed to obtain the phase, by eliminating the noise from the shape components of the interferograms in the Fourier domain. However, when the noise and shape components overlap in the Fourier domain, it is difficult to eliminate only the overlapped noise components using conventional filtering techniques, such as bandpass filtering. Accordingly, a method is proposed to solve this problem using two interferograms with slightly different carrier frequencies. In this method, the Fourier transforms of two interferograms with slightly different carrier frequencies are separately calculated. Both of the spectra resulting from the Fourier transforms of the interferograms contain the same noise components; however, the locations of these components differ slightly for the two spectra. By subtracting the two Fourier spectra, the noise components are removed, and the main components are generated, because the frequency difference between the two components is small. We have named the proposed method the "two-step Fourier transpose method". The validity of the proposed filtering method is confirmed by experiments in which two color fringes are projected simultaneously onto a scatter object. Images of the color fringes are acquired via a CCD camera under the slow deformation of the scatter object. The images are then analyzed via the proposed method.

Kamiya, Kazuhide; Nomura, Takashi; Tanbo, Ami; Kimihisa, Matsumoto; Hatsuzou, Tashiro; Suzuki, Shinya

2012-11-01

277

Development of out-of-core fast Fourier transform software for the connection machine. Final report  

SciTech Connect

This report describes the algorithm and implementation of an out-of-core Fast Fourier Transform routine for the Thinking Machines Corp. CM-5 parallel computer. The software has the capability of transforming multi-dimensional arrays that are both real and complex.

Sweet, R.; Wilson, J. [Univ. of Colorado, Denver, CO (United States). Center for Computational Mathematics

1995-10-01

278

Real-time Fourier transformation of magnetotelluric data. Final technical report No. 203  

Microsoft Academic Search

Power spectra estimates for magnetotelluric data are computed using a continuous Fourier transformation technique which is implemented in real time on a Hewlett-Packard 9825 programmable calculator. This technique, known as cascade decimation, applies 32 point sine and cosine transforms to sequences of data produced by successively applying a low pass digital filter and decimation by two operator to the original

D. E. Wight; F. X. Jr. Bostick; H. W. Smith

1977-01-01

279

Optical image encryption based on two-dimensional N-parameter fractional Fourier transform  

NASA Astrophysics Data System (ADS)

In this paper, the weighted fractional Fourier transform with dilation parameter (N-PFRFT) is proposed as the weighted combination of the first four integer-order ordinary Fourier transforms. This N-PFRFT is an extension of four-item weighted fractional Fourier transform (N-PFRFT) defined by Shih[1] and it owns four free parameters in the weight coefficients besides the order of the fractional Fourier transform. A novel image encryption algorithm is presented by the N-PFRFT.The method owns more secret keys than the encryption methods operated by other fractional Fourier transforms without any increase of the computational complexity. On the other hand, the image still can't be decrypted correctly even though the order of FRFT which is treated as a secret key is known. So do the four free parameters. Therefore, both the order parameter and the vector parameter can be chosen in the real domain to improve the security of the encryption method. Digital simulations are presented to verify the more validity and efficiency of the algorithm.

Zhang, Haiying; Ran, Qiwen; Xiao, Yu; Ma, Jing; Tan, Liying; Zhang, Jin; Wei, Deyun

2009-07-01

280

Green's Function of a Finite Chain and the Discrete Fourier Transform  

NASA Astrophysics Data System (ADS)

Unlike the Fourier series expansion, the discrete Fourier transform is defined on a finite basis set of harmonic functions. The first approach is widely used in condensed matter to describe the thermodynamic limit of various lattice models, while the latter did not receive sufficient development that would allow to address finite lattices. In the present paper a general expression for the Green's function of a finite one-dimensional lattice with nearest neighbor interaction is derived for the first time via discrete Fourier transform. Solution of the Heisenberg spin chain with periodic and open boundary conditions is considered as an example. Although the final expressions are completely equivalent to Bethe ansatz, the examples allow us to clarify the differences between the two approaches. On the other hand, it is explained why the well known results obtained by Fourier series expansion were incomplete and thus provides a deeper understanding of the approach.

Cojocaru, Sergiu

281

Real-time spectrum analysis using hardware Fourier and chirp-Z transformations  

Microsoft Academic Search

The paper emphasizes the wide variety of distinct block-schematic approaches to be adopted in analog implementations for real-time spectrum analysis by hardware Fourier and chirp-Z transformations. The discussion covers Fourier analysis by correlation, chirp-Z analysis by correlation, variants of chirp-Z correlation, chirp-Z analysis by matched filtering, matching the chirp waveform with a dispersive delay line, and some features common to

R. Benjamin

1979-01-01

282

Coherence Analyses of Event-Related Potentials Using Fourier and Wavelet Transforms  

Microsoft Academic Search

The EEG coherence is beneficial to investigate cortical connectivity of different brain regions in response to specific events. Recently, the wavelet-based coherence is suggested for this purpose due to that it can capture the time-varying characteristics of signals from which the Fourier transform would suffer. However, the quantitative comparison between Fourier and wavelet-based coherence is less addressed. In this paper

Hsiao-Lung Chan; Ling-Fu Meng; Pei-Kuang Chao; Ming-An Lin

2007-01-01

283

SITELLE: a wide-field imaging Fourier transform spectrometer for the Canada-France-Hawaii Telescope  

Microsoft Academic Search

We describe the concept of a new instrument for the Canada-France-Hawaii telescope (CFHT), SITELLE (Spectromètre Imageur à Transformée de Fourier pour l'Etude en Long et en Large de raies d'Emission), as well as a science case and a technical study of its preliminary design. SITELLE will be an imaging Fourier transform spectrometer capable of obtaining the visible (350 nm -

L. Drissen; A.-P. Bernier; L. Rousseau-Nepton; A. Alarie; C. Robert; G. Joncas; S. Thibault; F. Grandmont

2010-01-01

284

Multi-aperture Fourier transform imaging spectroscopy: theory and imaging properties  

Microsoft Academic Search

Fourier transform imaging spectroscopy (FTIS) can be performed with a multi-aperture optical system by making a series of intensity measurements, while introducing optical path differences (OPD's) between various subapertures, and recovering spectral data by the standard Fourier post-processing technique. The imaging properties for multi-aperture FTIS are investigated by examining the imaging transfer functions for the recovered spectral images. For systems

Samuel T. Thurman; James R. Fienup

2005-01-01

285

Fidelities for transformations of unknown quantum states  

SciTech Connect

We present a general theoretical formalism to compute the fidelity of transformations of unknown quantum states, and we apply our theory to Gaussian transformations of continuous variable quantum systems. For the case of a Gaussian distribution of displaced coherent states, the theory is readily tractable by a covariance matrix formalism, and a wider class of states, exemplified by Fock states, can be treated efficiently by the Wigner function formalism. Given the distribution of input states, the optimum feedback gain is identified, and analytical results for the fidelities are presented for recently implemented teleportation and memory storage protocols for continuous variables.

Madsen, Lars Bojer [Department of Physics and Astronomy, University of Aarhus, 8000 Aarhus C (Denmark); Moelmer, Klaus [Department of Physics and Astronomy, University of Aarhus, 8000 Aarhus C (Denmark); Department of Physics and Astronomy, QUANTOP-Danish National Research Foundation Center for Quantum Optics, University of Aarhus, 8000 Aarhus C (Denmark)

2006-03-15

286

Fourier transform infrared microspectroscopy used to identify foreign materials related to breast implants.  

PubMed

Clinically useful methods to identify and document the presence of foreign material in tissues surrounding breast implants are needed. Fourier transform infrared microspectroscopy is an ideal technique for examining tissue for the presence of implantable biomaterials. Because the spectroscopy is microscopically guided, the pathologist is assured that the obtained spectrum is from the region of interest in a tissue section. Scanning electron microscopy yields elemental data but cannot be used to identify compounds. Because each compound has a unique spectrum by Fourier transform infrared microspectroscopy, the spectrum obtained enables identification of the various foreign materials observed by light microscopy in tissues surrounding breast implants. Histopathology from implant capsules demonstrating a silicone gel-filled implant, a saline-filled textured implant, a polyurethane foam-covered gel-filled implant, a Dacron fixation patch, and a paraffin injection granuloma are presented with corresponding Fourier transform infrared microspectroscopy spectra. PMID:7991526

Hardt, N S; Yu, L T; La Torre, G; Steinbach, B

1994-08-01

287

[Research on key technologies of all fiber optic Fourier transform spectrometer].  

PubMed

A noval all fiber optic Fourier transform spectrometer based on single mode fiber Mach-Zehnder interferometer is reported. The authors designed a piezoelectric optical phase modulator with two centimeter scan scale, which was used to replace the moving mirror of traditonal Fourier transform spectrometer. The 1 310 nm DFB laser was used as reference light source to make equal interval sampling of test light source's interferogram, and to eliminate errors of nonlinear modulation. Through making the inverse Fourier transform to test light source's interferogram, the authors obtained the spectrum of test source. The spectrum of ASE broadband light source was measured by FFTS system, and the experiment result agrees with that tested by grating spectrometer. Finally, the authors utilized fiber grating as sample to measure the resolution of FFTS system, and the spectral resolution is 0.78 cm(-1). PMID:19798938

Wang, An; Zhu, Ling; Zhang, Long; Liu, Yong; Zhu, Zhen; Li, Zhi-Gang; Wu, Jian-Dong; Fan, Yan-Ping

2009-07-01

288

Enhanced Optical Image Verification Based on Joint Transform Correlator Adopting Fourier Hologram  

NASA Astrophysics Data System (ADS)

In this paper two new architectures for optical image verification are proposed. Both architectures are based on conventional joint transform correlators (JTCs) adopting a Fourier hologram and can significantly improve the recovered image quality. First, an input phase-only function is Fourier transformed and then interferes with a reference wave that is diffracted from a plane wave incident on another random phase mask. Second, two phase-only functions are placed at the two input sides of a beamsplitter such that the interference pattern of their Fourier transforms can be detected. To obtain a predefined target image in the output plane, one of the input phase functions is iteratively retrieved by the use of the projection onto constraint sets algorithm. Simulation results show that the less mean squared error and better image quality are obtained for both the binary and grayscale images.

Chang, Hsuan T.; Chen, Ching T. T.

2004-05-01

289

Integrated test plan for the demonstration of a commercial Fourier Transform Infrared instrument  

SciTech Connect

This integrated test plan describes the use of a commercial Fourier Transform Infrared instrument for measuring Carbon Tetrachloride concentrations. The Fourier Transform Infrared will measure CCL4 concentrations in a line of sight path average mode in mass per cubic meter as a function of time. The goal of this test is to demonstrate the usefulness of a long path Fourier Transform Infrared instrument in determining CCL4 fluxes from the soil in the 200 area adjacent to disposal cribs where high soil fluxes are believed to exist. The instrument will be set up such that it can have a clear line of site path to it`s reflector and this line of site will be as near to the Z-9 fence as possible and have a path length as long as possible.

Koegler, K.J.

1993-08-01

290

Integrated test plan for the demonstration of a commercial Fourier Transform Infrared instrument  

NASA Astrophysics Data System (ADS)

This integrated test plan describes the use of a commercial Fourier Transform Infrared instrument for measuring carbon tetrachloride concentrations. The Fourier Transform Infrared will measure CCL4 concentrations in a line of sight path average mode in mass per cubic meter as a function of time. Demonstration of this device will be conducted at the 200 West Area Carbon Tetrachloride Expedited Response Action (ERA) site. The goal of this test is to demonstrate the usefulness of a long path Fourier Transform Infrared instrument in determining CCL4 fluxes from the soil in the 200 area adjacent to disposal cribs where high soil fluxes are believed to exist. The instrument will be set up such that it can have a clear line of site path to its reflector and this line of site will be as near to the Z-9 fence as possible and have a path length as long as possible.

Koegler, K. J.

1993-06-01

291

A study of pyrolysis of polymethylsiloxanes by Fourier transform infrared.  

PubMed

This paper is dedicated to a comparative study of pyrolysis of decamethylcyclopentasiloxane and hexamethyldisiloxane, widely used as precursors for CVD of silicon dioxide films. The pyrolysis process was carried out in a hot-wall horizontal tube reactor made from quartz within the temperature range 25-1000 degrees C. FTIR spectroscopy has been used for the analysis of gaseous reaction products in the exhaust line of the reactor. It has been found that transformation of DMPSO was initiated by the open ring in the precursor molecules with its further transformation to linear biradicals followed by the chain's growth due to radical reactions. HMDSO transformation is connected with separation of silanon, silyl and methyl radicals with following multi-type interactions of siloxane radicals and formation of non-rigorously organized three-dimensional molecules. PMID:22097543

Alexandrov, S E; Filatov, L A; Solovyeva, A S

2011-09-01

292

Flexible, runtime-efficient vector-radix algorithms for multidimensional fast Fourier transform  

NASA Astrophysics Data System (ADS)

Dynamic development in digital signal processing is inseparably bound to the disclosure of the fast Fourier transform (FFT). Implications from the application of these efficient algorithms for calculating the discrete (inverse) Fourier transform are significant in many ways. Applicability of FFT algorithms ranges far into almost every aspect of physics and performs a central role in analysis, design and implementation of DSP algorithms and digital systems. Consumed computer time almost ceases to be a problem when using FFT compared with straightforward discrete Fourier transform (DFT). The cutdown on consumed computer time by usage of FFT algorithms even holds greater promise for multidimensional applications with in general more complex tasks and heavier data loads to cope with. Without multidimensional FFT algorithms for high speed convolution or spectral analysis the successes for example in SAR, tomography, data compression or picture processing could not have been achieved. Since the introduction of the Cooley-Tukey-algorithm in 1965 methods to calculate the two- or N dimensional Fourier transform of a set of data are based essentially on the separability of the 2D FFT. With a 1D FFT algorithm the data set is `combed' row- and columnwise to form the 2D transform of the calculated 1D transforms. After some basics and recalling some different conventional approaches to 1D and 2D Fourier transform the paper concentrates on Vector-Radix-algorithms which decimate and transform a 2D data set simultaneous for both index directions and therefore seem suitable for parallelization. Vector-Radix-approaches are derived for general radices and for the 2D case also for nonquadratic data sets.

Klaus, Ferdinand; Blewonska, Ute; Bundschuh, Bernhard O.

1994-11-01

293

A program transformation and architecture support for quantum uncomputation  

Microsoft Academic Search

Quantum computing's power comes from new algorithms that exploit quantum mechanical phenomena for computation. Quantum algorithms are different from their classical counterparts in that quantum algorithms rely on algorithmic structures that are simply not present in classical computing. Just as classical program trans- formations and architectures have been designed for common classi- cal algorithm structures, quantum program transformations and quantum

Ethan Schuchman; T. N. Vijaykumar

2006-01-01

294

Simple example of track finding by Fourier transform and possibilities for vector or optical processors  

SciTech Connect

Simple examples of finding tracks by Fourier transform with filter or correlation function are presented. Possibilities for using this method in more complicated real situations and the processing times which might be achieved are discussed. The method imitates the simplest examples in the literature on optical pattern recognition and optical processing. The possible benefits of the method are in speed of processing in the optical Fourier transform wherein an entire picture is processed simultaneously. The speed of a computer vector processor may be competitive with present electro-optical devices. 2 refs., 6 figs.

Underwood, D.

1986-09-05

295

Hydrocarbon characterization by ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry  

SciTech Connect

The ultrahigh-resolution capabilities of Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) have been demonstrated for accurate mass measurements of complex hydrocarbon mixtures. Ultrahigh resolution is achievable over a wide mass range by the use of stored waveform inverse Fourier transform (SWIFT) ejection to eliminate space-charge effects. The mass measurement stability under different ionization conditions eliminates the need of mass reference standards during acquisition of sample spectra, thereby increasing sensitivity of the accurate mass measurements under low-voltage electron ionization conditions. 27 refs., 4 figs., 2 tabs.

Hsu, C.S. (Exxon Research and Engineering Company, Annandale, NJ (United States)); Liang, Z. (Exxon Research and Engineering Company, Annandale, NJ (United States) Millipore Corporation, Madison, WI (United States)); Campana, J.E. (Millipore Corporation, Madison, WI (United States))

1994-03-15

296

Local structure information by EXAFS analysis using two algorithms for Fourier transform calculation  

NASA Astrophysics Data System (ADS)

The present work is a comparison study between different algorithms of Fourier transform for obtaining very accurate local structure results using Extended X-ray Absorption Fine Structure technique. In this paper we focus on the local structural characteristics of supported nickel catalysts and Fe3O4 core-shell nanocomposites. The radial distribution function could be efficiently calculated by the fast Fourier transform when the coordination shells are well separated while the Filon quadrature gave remarkable results for close-shell coordination.

Aldea, N.; Pintea, S.; Rednic, V.; Matei, F.; Tiandou, Hu; Yaning, Xie

2009-08-01

297

The Los Alamos Fourier-transform spectrometer: Applications to molecular spectroscopy  

SciTech Connect

We outline design considerations and operating characteristics of the Los Alamos Fourier-transform spectrometer, a state-of-the-art instrument operating from 200 nm to 20 ..mu..m with a resolution of 0.0026 cm/sup /minus/1/ and very high wave number and intensity accuracy. Recent work in molecular spectroscopy carried out with this instrument will be discussed, including N/sub 2//sup +/ spectra obtained in inductively-coupled plasmas; high-temperature spectra of diatomic molecules of astrophysical interest; high-resolution rovibrational fine structure; and Fourier-transform Raman spectroscopy of species in expansion-cooled gases. 8 refs., 5 figs., 4 tabs.

Palmer, B.A.; McDowell, R.S.

1989-01-01

298

Phase-shifting algorithm via wavelength tuning based on temporal Fourier transform  

NASA Astrophysics Data System (ADS)

The phase-shifting algorithm via wavelength tuning based on temporal Fourier transform is according to the Fourier transform technique and the difference technique to realize the processing of the interferogram. This algorithm is applied to test some course profiles or the topography with high steps. The paper describes its main idea and presents the shortcoming of the algorithm proposed by Takeda. Then it puts forward the improved algorithml. The pape describes the realization processing and the errors of the new algorithm. Finally, it supplies the measurement result.

Yu, Yingjie; Zhang, Benhao; Jiao, Yunfang

2003-11-01

299

Amplified dispersive Fourier-transform imaging for ultrafast displacement sensing and barcode reading  

NASA Astrophysics Data System (ADS)

Dispersive Fourier transformation is a powerful technique in which the spectrum of an optical pulse is mapped into a time-domain waveform using chromatic dispersion. It replaces a diffraction grating and detector array with a dispersive fiber and single photodetector. This simplifies the system and, more importantly, enables fast real-time measurements. Here we describe a novel ultrafast barcode reader and displacement sensor that employs internally amplified dispersive Fourier transformation. This technique amplifies and simultaneously maps the spectrally encoded barcode into a temporal waveform. It achieves a record acquisition speed of 25 MHz-four orders of magnitude faster than the current state of the art.

Goda, Keisuke; Tsia, Kevin K.; Jalali, Bahram

2008-09-01

300

Transformation in mandibular imaging with sweep imaging with fourier transform magnetic resonance imaging  

PubMed Central

Objective Current imaging techniques are often sub-optimal for the detection of mandibular invasion by squamous cell carcinoma. The aim of this study was to determine the feasibility of a magnetic resonance imaging (MRI) based technique known as Sweep Imaging with Fourier Transform (SWIFT) to visualize the structural changes of intra-mandibular anatomy during invasion. Design Descriptive case study Setting Tertiary academic institution Method Two specimens from patients with oral carcinoma who underwent segmental mandibulectomy were imaged using a 9.4 Tesla Varian MRI system. The SWIFT images were correlated with histological sections. Results The SWIFT technique with in vitro specimens produced images with sufficient resolution (156–273) and contrast to allow accurate depiction of tumor invasion of cortical and medullary bone. Both specimens had histopathological evidence of mandibular invasion with tumor. A high degree of correlation was found between MR images and histopathologic findings. Conclusion SWIFT MRI offers three-dimensional assessment of cortical and medullary bone in fine detail with excellent qualitative agreement with histopathology. MR imaging with the SWIFT technique demonstrates great potential to identify mandibular invasion by oral carcinoma.

Kendi, Ayse Tuba Karagulle; Khariwala, Samir S.; Zhang, Jinjin; Idiyatullin, Djaudat S.; Corum, Curtis A.; Michaeli, Shalom; Pambuccian, Stefan E.; Garwood, Michael; Yueh, Bevan

2012-01-01

301

High-resolution magnetic-domain imaging by Fourier transform holography at 21 nm wavelength  

NASA Astrophysics Data System (ADS)

Exploiting x-ray magnetic circular dichroism at the L-edges of 3d transition metals, Fourier transform holography has become a standard technique to investigate magnetic samples with sub-100 nm spatial resolution. Here, magnetic imaging in the 21 nm wavelength regime using M-edge circular dichroism is demonstrated. Ultrafast pulses in this wavelength regime are increasingly available from both laser- and accelerator-driven soft x-ray sources. We explain the adaptations concerning sample preparation and data evaluation compared to conventional holography in the 1 nm wavelength range. We find the correction of the Fourier transform hologram to in-plane Fourier components to be critical for high-quality reconstruction and demonstrate 70 nm spatial resolution in magnetization imaging with this approach.

Schaffert, Stefan; Pfau, Bastian; Geilhufe, Jan; Günther, Christian M.; Schneider, Michael; von Korff Schmising, Clemens; Eisebitt, Stefan

2013-09-01

302

Discrete Fourier Transform based multimedia colour image authentication for wireless communication (DFTMCIAWC)  

Microsoft Academic Search

T his paper presents a novel steganographic schemes based on Discrete Fourier Transformation (DFT) and demonstrates the multimedia colour image authentication process in frequency domain for wireless communication(DFTMCIAWC). Authentication is done through embedding secrete message\\/image into the transformed frequency components of the source image at message originating node. The DFT is applied on sub-image block called mask of size 2

Nabin Ghoshal; J. K. Mandal

2011-01-01

303

Quantum measurement and the transformation from quantum to classical probabilities  

NASA Astrophysics Data System (ADS)

A specific model of quantum measurement [D. F. Walls, M. J. Collet, and G. J. Milburn, Phys. Rev. D 32, 3208 (1985)] based on a generic system-meter-environment measurement scheme is investigated in terms of probability distributions on projective Hilbert space. Starting from the unitary evolution of the total system a stochastic process for the wave function of the reduced system-meter system is derived by elimination of the degrees of freedom of the environment. The stochastic process is interpreted in terms of the direct detection of the photoelectrons created by the meter quanta in the environment. Two general variances are introduced which represent, respectively, the average intrinsic quantum fluctuations and the statistical fluctuations of the quantum expectation of the measured observable. Involving fourth moments of the wave function, these variances allow to monitor the transformation from quantum to classical probabilities during the process of measurement.

Breuer, Heinz-Peter; Petruccione, Francesco

1996-08-01

304

Terahertz spectroscopy with a holographic Fourier transform spectrometer plus array detector using coherent synchrotron radiation  

SciTech Connect

By use of coherent terahertz synchrotron radiation, we experimentally tested a holographic Fourier transform spectrometer coupled to an array detector to determine its viability as a spectral device. Somewhat surprisingly, the overall performance strongly depends on the absorptivity of the birefringent lithium tantalate pixels in the array detector.

Nikolay I. Agladz, John Klopf, Gwyn Williams, Albert J. Sievers

2010-06-01

305

Lossless compression of the geostationary imaging Fourier transform spectrometer (GIFTS) data via predictive partitioned vector quantization  

Microsoft Academic Search

The Geostationary Imaging Fourier Transform Spectrometer (GIFTS), as part of NASA's New Millennium Program, is an advanced instrument to provide high-temporal-resolution measurements of atmospheric temperature and water vapor, which will greatly facilitate the detection of rapid atmospheric changes associated with destructive weather events, including tornadoes, severe thunderstorms, flash floods, and hurricanes. The Committee on Earth Science and Applications from Space

Bormin Huang; Shih-Chieh Wei; Allen H.-L. Huang; Maciek Smuga-Otto; Robert Knuteson; Henry E. Revercomb; William L. Smith Sr.

2007-01-01

306

Towards data acquisition throughput increase in Fourier transform mass spectrometry of proteins using double frequency measurements  

Microsoft Academic Search

Combined with high and ultra high pressure liquid chromatography, mass spectrometry-based peptide and protein structure analysis requires high resolution and mass accuracy achievable within short ion detection time. Although Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR MS) offers highest resolution and mass accuracy among all types of mass spectrometers, it is unacceptably slow for many applications in proteomics requiring

Aleksey Vorobyev; Mikhail V. Gorshkov; Yury O. Tsybin

2011-01-01

307

Ab initio prediction of metabolic networks using Fourier transform mass spectrometry data  

Microsoft Academic Search

Fourier transform mass spectrometry has recently been introduced into the field of metabolomics as a technique that enables the mass separation of complex mixtures at very high resolution and with ultra high mass accuracy. Here we show that this enhanced mass accuracy can be exploited to predict large metabolic networks ab initio, based only on the observed metabolites without recourse

Rainer Breitling; Shawn Ritchie; Dayan Goodenowe; Mhairi L. Stewart; Michael P. Barrettb

2006-01-01

308

Petroleomics Applications of Fourier Transform Ion Cyclotron Resonance Mass Spectrometry: Crude Oil and Bitumen Analysis  

Microsoft Academic Search

The ultra-high mass resolving power and high mass accuracy of Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) have been shown to be well suited for the characterization of highly complex mixtures. Petroleum mixtures, arguably the most complex on the planet, have been extensively characterized by FT-ICR MS. This new field of \\

Donald Francis Smith

2007-01-01

309

The data processing pipeline for the Herschel\\/SPIRE Imaging Fourier Transform Spectrometer  

Microsoft Academic Search

We present the data processing pipeline to generate calibrated data products from the Spectral and Photometric Imaging Receiver (SPIRE) imaging Fourier Transform Spectrometer. The pipeline processes telemetry from SPIRE point source, jiggle- and raster-map observations, producing calibrated spectra in low-, medium-, high-, and mixed low- and high- resolution modes. The spectrometer pipeline shares some elements with the SPIRE photometer pipeline,

Trevor R. Fultona; David A. Naylorb; Peter Davis-Imhofa; M. Swinyarde; Tanya L. Lime; Nanyao Luh; France Marseille

310

Detection of exposure damage in composite materials using Fourier transform infrared technology  

Microsoft Academic Search

Goal: to detect the subtle changes in laminate composite structures brought about by thermal, chemical, ultraviolet, and moisture exposure. Compare sensitivity of an array of NDI methods, including Fourier Transform Infrared Spectroscopy (FTIR), to detect subtle differences in composite materials due to deterioration. Inspection methods applied: ultrasonic pulse echo, through transmission ultrasonics, thermography, resonance testing, mechanical impedance analysis, eddy current,

Dennis Patrick Roach; Randy L. Duvall

2010-01-01

311

Identification of Bacterial Spores using Statistical Analysis of Fourier Transform Infrared Photoacoustic Spectroscopy Data  

Microsoft Academic Search

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,

Sandra E. Thompson; Nancy S. Foster; Timothy J. Johnson; Nancy B. Valentine; James E. Amonette

2003-01-01

312

Qualitative and quantitative analysis of wood samples by Fourier transform infrared spectroscopy and multivariate analysis  

Microsoft Academic Search

Fourier transform infrared (FTIR) spectroscopy, in combination with multivariate analysis, enable the analysis of wood samples without time-consuming sample preparation. The aim of our work was to analysis the wood samples qualitatively and quantitatively by FTIR spectroscopy. A Van Soest method to determine the lignin, cellulose and hemicellulose content, was used as reference method. Multivariate calibration was performed based on

Huilun Chen; Carlo Ferrari; Marco Angiuli; Jun Yao; Costantino Raspi; Emilia Bramanti

2010-01-01

313

Experimental design protocol for the pattern recognition analysis of bandpass filtered Fourier transform infrared interferograms  

Microsoft Academic Search

Signal processing techniques are described for open path Fourier transform infrared (FTIR) measurements that overcome fundamental limitations in conventional data analysis strategies. Bandpass digital filters are applied directly to FTIR interferograms to isolate spectral frequencies of interest, followed by pattern recognition analysis of segments of the filtered interferogram to provide an automated means for detecting a target analyte. In this

Ronald E. Shaffer; Gary W. Small; Roger J. Combs; Robert B. Knapp; Robert T. Kroutil

1995-01-01

314

Incoherent optical two-dimensional Fourier transform using the chirp-z algorithm  

NASA Astrophysics Data System (ADS)

An incoherent optical method for computing two-dimensional complex-valued Fourier transforms is described. It is based on implementing the two-dimensional chirp-z algorithm with incoherent optical convolutions and indirect representation of complex-valued functions.

Glaser, I.; Katzir, Y.; Toschi, V.

1984-06-01

315

Incoherent optical two-dimensional Fourier transform using the chirp-z algorithm.  

PubMed

An incoherent optical method for computing two-dimensional complex-valued Fourier transforms is described. It is based on implementing the two-dimensional chirp-z algorithm with incoherent optical convolutions and indirect representation of complex-valued functions. PMID:19721543

Glaser, I; Katzir, Y; Toschi, V

1984-06-01

316

Topics in Chemical Instrumentation: Fourier Transform-Infrared Spectroscopy: Part I. Instrumentation.  

ERIC Educational Resources Information Center

|Discusses: (1) the design of the Fourier Transform-Infrared Spectroscopy (FT-IR) spectrometer; (2) the computation of the spectrum from the interferogram; and (3) the use of apodization. (Part II will discuss advantages of FT-IR over dispersive techniques and show applications of FT-IR to difficult spectroscopic measurements.) (JN)|

Perkins, W. D.

1986-01-01

317

An Inverse Fourier Transform for In-Place Continuous-Wave Data Reduction.  

National Technical Information Service (NTIS)

The selection and testing of an inverse Fourier transform (IFT) algorithm for use with Minuteman In-Place continuous-wave (CW) data are described. The CW data are obtained in the presence of noise at unequally spaced frequency intervals; the time response...

H. G. Heubach A. G. Larson R. C. Singleton

1974-01-01

318

Using a Fourier transform spectrometer for tropospheric UV-visible DOAS measurements  

Microsoft Academic Search

Concentration measurements of trace gases in the atmosphere require the use of highly sensitive and precise techniques. The UV-visible DOAS technique is one of them heavily used for tropospheric measurements. In order to assess the advantages and drawbacks of using a Fourier transform spectrometer, we have built a DOAS optical setup based on a Bruker IFS 120M spectrometer. The characteristics

Michel Carleer; Reginald Colin; Ann Carine Vandaele

1998-01-01

319

Classification of select category A and B bacteria by Fourier transform infrared spectroscopy  

Microsoft Academic Search

Relatively few reports have investigated the determination and classification of pathogens such as the National Institute of Allergy and Infectious Diseases (NIAID) Category A Bacillus anthracis spores and cells (BA), Yersinia species, Francisella tularensis (FT), and Category B Brucella species from FTIR spectra. We investigated the classification ability of the Fourier transform infrared (FTIR) spectra of viable pathogenic and non-pathogenic

Alan C. Samuels; A. Peter Snyder; Diane St. Amant; Darren K. Emge; Jennifer Minter; Mark Campbell; Ashish Tripathi

2008-01-01

320

Fourier transform Raman microscopic study of drug distribution in a transdermal drug delivery device  

Microsoft Academic Search

The mapping facility of a Fourier transform Raman microscope was used to construct a profile of oestradiol distribution in a transdermal drug delivery device (Hormone Replacement Therapy patch). Mapping was performed across a region of the patch which contained crystallised material for characterisation. The spectra acquired using the microscope facility were compared with those obtained of pure oestradiol and of

Clare L. Armstrong; Howell G. M. Edwards; Dennis W. Farwell; Adrian C. Williams

1996-01-01

321

Fourier transform imaging spectroscopy with a multiple-aperture telescope: band-by-band image reconstruction  

Microsoft Academic Search

Fourier transform imaging spectroscopy can be performed with a segmented-aperture telescope or a multiple-telescope array using the subaperture piston control mechanisms. Spectrum recovery from intensity measurements is analyzed for a general aperture configuration. The spatial transfer functions of the recovered spectral images are shown to vanish necessarily at the DC spatial frequency. This poses an interesting image reconstruction problem as

Samuel T. Thurman; James R. Fienup

2004-01-01

322

Reconstruction of multispectral image cubes from multiple- telescope array Fourier transform imaging spectrometer  

Microsoft Academic Search

Multiple-telescope arrays can function as Fourier transform imaging spectrometers, using the subaperture path-delay elements. However, the resulting spectral images are missing low spatial-frequency content. Reconstruction results are presented for a cube of simulated data using a nonlinear derivative-based sharpness metric that is designed for specific types of imagery.

Samuel T. Thurman; James R. Fienup

323

Copyright protection of vector map using digital watermarking method based on discrete Fourier transform  

Microsoft Academic Search

In this paper, a new digital watermarking method for vector maps is proposed, where the watermark can be embedded in a set of polylines by using the discrete Fourier transform (DFT). The robustness against external attacks and visual degradation caused by embedding were evaluated, and the effectiveness of the watermarking was confirmed. Our watermarking method is especially robust against vertex

I. Kitamura; S. Kanai; T. Kishinami

2001-01-01

324

Teaching Stable Two-Mirror Resonators through the Fractional Fourier Transform  

ERIC Educational Resources Information Center

|We analyse two-mirror resonators in terms of their fractional Fourier transform (FRFT) properties. We use the basic ABCD ray transfer matrix method to show how the resonator can be regarded as the cascade of two propagation-lens-propagation FRFT systems. Then, we present a connection between the geometric properties of the resonator (the g…

Moreno, Ignacio; Garcia-Martinez, Pascuala; Ferreira, Carlos

2010-01-01

325

Aller Interactions of Selenium Species with Living Bacterial Cells - A Fourier Transform Infrared Spectroscopy Approach  

Microsoft Academic Search

One area of astrobiology is devoted to duplicating conditions that exist on remote planets and moons (like Mars and Europa) on Earth, and studying the life that survives there. A variety of bacteria can thrive in inhospitable environments. An essential nutrient for life at low concentration can be a deadly poison at higher concentration. Fourier-transform infrared (FT-IR) spectroscopy is employed

J. C. Feo; M. A. Castro; S. R. Alford; A. J. Aller

326

Optical waveguide analysis using the Fourier transform and its application to intersecting waveguides  

Microsoft Academic Search

An analysis method for inhomogeneous waveguides which is effective even for the radiation mode light is derived and applied to study the propagation characteristics of intersecting waveguides. Considering virtual waveguides that include the real waveguide completely, the propagating light is expressed by the Fourier transform with virtual modes set up in the virtual waveguides. Using the concept of the power-flow

Minoru Seino; Hirochika Nakajima; Yoshimasa Daido; Ippei Sawaki; Kunihiko Asama

1984-01-01

327

Rapid species and strain differentiation of non-tubercoulous mycobacteria by FourierTransform Infrared microspectroscopy  

Microsoft Academic Search

Rapid identification of non-tuberculous mycobacteria (NTM) species is important in clinical laboratories to stipulate the appropriate therapy and to offer a comprehensive infection control. We applied Fourier-Transform Infrared microspectroscopy to evaluate, whether the most frequent species of NTM can be rapidly and uniformly identified by this method using microcolonies of NTM growing on solid nutrient agar plates. To establish a

Cecilia A. Rebuffo-Scheer; Carolin Kirschner; Maren Staemmler; Dieter Naumann

2007-01-01

328

Real-time detection of sine waves by means of a discrete Fourier transform  

Microsoft Academic Search

This paper deals with the problem of probabilistic detection of weak sine waves immersed in noise. The analysis is performed in the frequency domain after a discrete Fourier transform, and it is suited for real-time applications. The detection and false alarm probabilities are provided in analytical form as functions of the sampling parameters and the properties of the time window.

Diego Bellan

2009-01-01

329

Application of Fourier transform near-infrared spectroscopy to optimization of green tea steaming process conditions  

Microsoft Academic Search

In this study, we constructed prediction models by metabolic fingerprinting of fresh green tea leaves using Fourier transform near-infrared (FT-NIR) spectroscopy and partial least squares (PLS) regression analysis to objectively optimize of the steaming process conditions in green tea manufacture. The steaming process is the most important step for manufacturing high quality green tea products. However, the parameter setting of

Daiki Ono; Takeshi Bamba; Yuichi Oku; Tsutomu Yonetani; Eiichiro Fukusaki

2011-01-01

330

Development of secondary cell wall in cotton fibers as examined with Fourier transform-infrared spectroscopy  

Technology Transfer Automated Retrieval System (TEKTRAN)

Our presentation will focus on continuing efforts to examine secondary cell wall development in cotton fibers using infrared Spectroscopy. Cotton fibers harvested at 18, 20, 24, 28, 32, 36 and 40 days after flowering were examined using attenuated total reflection Fourier transform-infrared (ATR FT-...

331

Fourier Transform Infrared (FTIR) Spectroscopy for Monitoring Airborne Gases and Vapors of Industrial Hygiene Concern  

Microsoft Academic Search

There are few available analytical methods with which an industrial hygienist can perform near real-time identification and quantitation of gases and vapors in the workplace. At present, the instruments that come the closest to fulfilling this need are based on either Fourier transform infrared (FTIR) spectroscopy or mass spectroscopy (MS). In order to investigate the applicability of FTIR to the

YING LI-SHI; STEVEN P. LEVINE; CHRISTOPHER R. STRANG; WILLIAM F. HERGET

1989-01-01

332

MEASUREMENT OF ON-THE-FLY FOURIER TRANSFORM INFRARED REFERENCE SPECTRA OF ENVIRONMENTALLY IMPORTANT COMPOUNDS  

EPA Science Inventory

The United States Environmental Protection Agency (U.S. EPA) requires reference spectra to support its gas chromatography/Fourier transform infrared (GC/FT-IR) routine environmental monitoring program. Although on-the-fly (OTF) techniques are needed to satisfy the Agency's high s...

333

Fourier transform, wavelets, Prony analysis: tools for harmonics and quality of power  

Microsoft Academic Search

The Fourier transform is a very useful tool for signal studies. Nevertheless there are many problems in using it; but these problems are very well known and correctly explained in literature. Wavelets are not usual in power network analysis. However, they are easy to use and give good results; the edge effects are transient and the computation time may be

M. Meunier; F. Brouaye

1998-01-01

334

In situ Optical Histochemistry of Human Artery Using Near Infrared Fourier Transform Raman Spectroscopy  

Microsoft Academic Search

In this paper we demonstrate that near infrared Fourier transform Raman spectroscopy provides unprecedented biochemical information about the extent of atherosclerosis in human aorta. In particular, elastin, collagen, cholesterol, cholesterol esters, lipids, carotenoids, and calcium apatite deposits all can be discerned by using this technique, permitting study of each stage in the disease process. Additionally, these moieties can be detected

Joseph J. Baraga; Michael S. Feld; Richard P. Rava

1992-01-01

335

Identification of pollutant gases from an atmospheric mixture using high resolution Dispersive Fourier Transformation Spectroscopy  

Microsoft Academic Search

Dispersive Fourier Transformation Spectroscopy technique allows us to accurately measure the refractive index and absorption coefficient of pollutant gases over a wide range of frequencies from 0.3 - 0.9 Thz. This spectrum can be used to identify and detect a gas in a mixture. In this study, the absorption and refractive index data of carbon monoxide mixed with air is

Nawaf N. Almoayed; Golam R. Khan; Mohammed N. Afsar

2008-01-01

336

Precision high resolution fourier transform spectroscopy of greenhouse gases at millimeter and submillimeter wavelengths  

Microsoft Academic Search

Dispersive Fourier transform spectroscopy (DFTS) provides us with a very effective technique for the measurement of absorption and refractive index spectra of environmentally hazardous gases. This paper presents the rotational transition lines and refractive index spectra of Nitrous Oxide gas as a function of varying pressure using DFTS for the very first time. The relationship between the variation of the

N. N. Almoayed; G. R. Khan; M. N. Afsar

2008-01-01

337

High Resolution Dispersive Fourier Transform Spectroscopy for Pollutant Gases at Millimeter Wave and Terahertz Frequencies  

Microsoft Academic Search

Dispersive Fourier transform spectroscopy (DFTS) provides us with a very precise method of measuring the absorption and refractive index spectra of pollutant gases. This paper presents the rotational transition lines of sulfur dioxide gas as a function of varying pressure using DFTS for the very first time. The relationship between the variation of the pressure and the change in the

N. N. Almoayed; M. N. Afsar

2007-01-01

338

Kinetic energies and reactions of trapped ions in a Fourier transform ion cyclotron resonance mass spectrometer  

Microsoft Academic Search

Three independent investigations to ascertain the kinetic energies of trapped ions in a Fourier transform ion cyclotron resonance (FTICR) mass spectrometer were performed. Two of these studies were accomplished with the observation of ion-molecule reactions. The quantification of ion-molecule reaction rate constants as well as equilibrium constants was employed for ion kinetic energy determinations. The third inquiry relied on ion

Bruce

1992-01-01

339

Fourier transform ion cyclotron resonance versus time of flight for precision mass measurements.  

National Technical Information Service (NTIS)

Both Fourier Transform Ion Cyclotron Resonance and ICR Time-of-Flight mass spectroscopy (FTICR-MS and ICR-TOF-MS, respectively) have been applied to precision atomic mass measurements. This paper reviews the status of these approaches and compares their l...

R. T. Kouzes

1993-01-01

340

A Unified Approach to Fourier-Clifford-Prometheus Sequences, Transforms and Filter Banks  

Microsoft Academic Search

In this paper we develop a new unified approach to the so-called generalized Fourier-Clifford-Prometheus sequences, transforms (FCPTs) and M-channel Filter Banks. It is based on a new generalized FCPT-generating construction. This construction has a rich algebraic structure that supports a wide range of fast algorithms.

Ekaterina L.-Rundblad; Valeriy Labunets; Ilya Nikitin

341

Comparison of countershock prediction features based on autoregressive and fourier transformed spectral analysis  

Microsoft Academic Search

Spectral analysis of ventricular fibrillation (VF) ECG has been used for predicting countershock success, where the Fast Fourier Transformation (FFT) is the standard spectral estimator. Autoregressive (AR) spectral estimation should compute the spectrum with less computation time. This study compares the predictive power and computational performance of features based on FFT and AR methods. In an animal model of VF,

C. N. Nowak; G. Fischer; A. Neurauter; L. Wieser; B. Tilg; H. U. Strohmenger

2008-01-01

342

Chapter 5: Volcanic Fluorine Emissions: Observations by Fourier Transform Infrared Spectroscopy  

Microsoft Academic Search

Volcanoes are an important natural source of fluorine to the environment. For several decades, fluorine emissions from volcanoes have been measured by laboratory analysis of samples collected in situ, and abundances compared with other gas species to infer magmatic and hydrothermal processes occurring at depth. More recently, open-path Fourier transform infrared (OP-FTIR) spectroscopy has been applied to field measurements of

Georgina M. Sawyer; Clive Oppenheimer

2006-01-01

343

Fourier-transform ghost imaging with pure far-field correlated thermal light  

NASA Astrophysics Data System (ADS)

Pure far-field correlated thermal light beams are created with phase grating, and Fourier-transform ghost imaging depending only on the far-field correlation is demonstrated experimentally. Theoretical analysis and the results of experimental investigation of this pure far-field correlated thermal light are presented. Applications which may be exploited with this imaging scheme are discussed.

Liu, Honglin; Shen, Xia; Zhu, Da-Ming; Han, Shensheng

2007-11-01

344

Quantitative evaluation of ion signal detection in analytically important Fourier transform ion cyclotron resonance mass spectrometry  

Microsoft Academic Search

Experiments performed in a Fourier transform ion cyclotron resonance (FTICR) mass spectrometer are evaluated to produce quantitatively reliable mass spectra in which the ion population in the trapped-ion cell is proportional to the image current. Generation of signal intensity profiles as a function of excitation voltage is described for analyzing ion cloud evolution in response to the effect of system

Riegner

1993-01-01

345

Optimal Methods for Processing Mineralized Tissues for Fourier Transform Infrared Microspectroscopy  

Microsoft Academic Search

Fourier transform infrared microspectroscopy (FTIRM) and infrared imaging (FTIRI) are techniques utilized in the analysis of bone mineral and matrix properties in health and disease. Since the spatial arrangement of bone tissue is conserved using FTIRM and FTIRI, quantitative data can be obtained on bone mineral (hydroxyapatite) crystalline size and composition, and on matrix structure and composition at discrete anatomic

S. Aparicio; S. B. Doty; N. P. Camacho; E. P. Paschalis; L. Spevak; R. Mendelsohn; A. L. Boskey

2002-01-01

346

Advances in Data Processing for Open-path Fourier Transform Infrared Spectrometry of Greenhouse Gases  

Technology Transfer Automated Retrieval System (TEKTRAN)

The automated quantification of three greenhouse gases, ammonia, methane and nitrous oxide, in the vicinity of a large dairy farm by open-path Fourier transform infrared (OP/FT-IR) spectrometry at intervals of 5 minutes is demonstrated. Spectral pretreatment, including the detection and correction ...

347

QUANTITATIVE ANALYSIS OF FAT AND MOISTURE IN MAYONNAISE USING FOURIER TRANSFORM INFRARED SPECTROMETER  

Microsoft Academic Search

A rapid method for quantitative determination of fat and moisture in a variety of mayonnaise products (regular, reduced- and low-fat) was developed using Fourier Transform Infrared (FTIR) spectroscopy. Both the fat and moisture contents could be effectively solvated out of the soluble solids using 1-propanol without sonication. A load cell assembly with a 100 mm Teflon spacer gave sufficient separation under

Alison L. Chippie; Peter R. Jamieson; Caroline M. Golt; Chia-Hua Hsu; Y. Martin Lo

2002-01-01

348

Fourier transform infrared spectroscopic study of the thermal stability of peroxyacetyl nitrate  

Microsoft Academic Search

The unimolecular decomposition of peroxyacetyl nitrate (PAN) to form methyl nitrate and carbon dioxide has been studied over the temperature range 298-338 K by Fourier transform infrared spectroscopy (FTIR). Pure PAN samples (> 98%; 2-30 torr) were found to decompose thermally, nearly quantitatively, to these products, with the only other observed product being nitromethane (< 10%). Both PAN decomposition and

Gunnar I. Senum; R. Fajer; J. S. Gaffney

1986-01-01

349

Terahertz Fourier transform characterization of biological materials in a liquid phase  

Microsoft Academic Search

Significant progress has been achieved during the last several years relating to experimental and theoretical aspects of terahertz (or submillimetre wave) Fourier transform spectroscopy of biological macromolecules. However, previous research in this spectral range has been focused on bio-materials in solid state since it was common opinion that high water absorption will obscure the spectral signatures of the bio-molecules in

Tatiana Globus; Dwight Woolard; Thomas W. Crowe; Tatyana Khromova; Boris Gelmont; Jeffrey Hesler

2006-01-01

350

Waveguide Chirped-Pulse Fourier Transform Microwave Spectroscopy of 2-ETHOXYETHANOL  

NASA Astrophysics Data System (ADS)

The pure rotational spectrum of 2-ethoxyethanol was recorded from 8.7 to 26.5 GHz at 250 K with a waveguide chirped-pulse Fourier transform microwave spectrometer. The full spectrum contains contributions from multiple vibrational states. Preliminary assignments have been made with a combination of ab initio calculations and an automated spectral fitting program that accelerates the initial fitting process.

Phillips, Maria A.; Shipman, Steven T.

2013-06-01

351

Amplified Dispersive FourierTransform Imaging for Ultrafast Displacement Sensing and Barcode Reading  

Microsoft Academic Search

Dispersive Fourier transformation is a powerful technique in which the spectrum of an optical pulse is mapped into a time-domain waveform using chromatic dispersion. It replaces a diffraction grating and detector array with a dispersive fiber and single photodetector. This simplifies the system and, more importantly, enables fast real-time measurements. Here we describe a novel ultrafast barcode reader and displacement

Keisuke God; Kevin K. Tsi; Bahram Jalali

352

Numerical Simulations of the Fourier-Transformed Vlasov-Maxwell System in Higher Dimensions---Theory and Applications  

Microsoft Academic Search

We present a review of recent developments of simulations of the Vlasov-Maxwell system of equations using a Fourier transform method in velocity space. In this method, the distribution functions for electrons and ions are Fourier transformed in velocity space, and the resulting set of equations are solved numerically. In the original Vlasov equation, phase mixing may lead to an oscillatory

Bengt Eliasson

2010-01-01

353

A general analytical solution for flow to a single horizontal well by Fourier and Laplace transforms  

NASA Astrophysics Data System (ADS)

The objective of this paper is to present an analytical solution for describing the head distribution in an unconfined aquifer with a single pumping horizontal well parallel to a fully penetrating stream. The Laplace-domain solution is developed by applying Fourier sine, Fourier and Laplace transforms to the governing equation as well as the associated initial and boundary conditions. The time-domain solution is obtained after taking the inverse Laplace transform along with the Bromwich integral method and inverse Fourier and Fourier sine transforms. The upper boundary condition of the aquifer is represented by the free surface equation in which the second-order slope terms are neglected. Based on the solution and Darcy's law, the equation representing the stream depletion rate is then derived. The solution can simulate head distributions in an aquifer infinitely extending in horizontal direction if the well is located far away from the stream. In addition, the solution can also simulate head distributions in confined aquifers if specific yield is set zero. It is shown that the solution can be applied practically to evaluate flow to a horizontal well.

Huang, Ching-Sheng; Chen, Yu-Lin; Yeh, Hund-Der

2011-05-01

354

Fourier-Transform Raman and Fourier-Transform Infrared Spectroscopy (An Investigation of Five Higher Plant Cell Walls and Their Components).  

PubMed Central

Infrared and Raman spectra of sequentially extracted primary cell walls and their pectic polymers were obtained from five angiosperm plants. Fourier-transform Raman spectrometry was shown to be a powerful tool for the investigation of primary cell-wall architecture at a molecular level, providing complementary information to that obtained by Fourier-transform infrared microspectroscopy. The use of an extraction procedure using imidazole instead of cyclohexane trans-1,2-N,N,N[prime],N[prime]-diaminotetraacetate allows the extension of the infrared spectral window for data interpretation from 1300 to 800 cm-1, to 2000 to 800 cm-1, and allows us to obtain Raman spectra from extracted cell-wall material. Wall constituents such as pectins, proteins, aromatic phenolics, cellulose, and hemicellulose have characteristic spectral features that can be used to identify and/or fingerprint these polymers without, in most cases, the need for any physical separation. The Gramineae (rice [Oryza sativa], polypogon [Polypogon fugax steud], and sweet corn [Zea mays]) are spectroscopically very different from the nongraminaceous monocotyledon (onion [Allium cepa]) and the dicotyledon (carrot [Daucus carota]); this reflects differences in chemical composition and cross-linking of the walls. The possibility of a taxonomic classification of plant cell walls based on infrared and Raman spectroscopies and the use of spectral fingerprinting for authentication and detection of adulteration of products rich in cell-wall materials are discussed.

Sene, CFB.; McCann, M. C.; Wilson, R. H.; Grinter, R.

1994-01-01

355

Fourier transform IR and Fourier transform Raman spectroscopy studies of metallothionein-III: amide I band assignments and secondary structural comparison with metallothioneins-I and -II.  

PubMed

The secondary structures of porcine brain Cu(4)Zn(3)-metallothionein (MT)-III and Cd(5)Zn(2)MT-I, Cd(5)Zn(2)MT-II, and Zn(7)MT-I from rabbit livers in the solid state are investigated by Fourier transform IR spectroscopy (FTIR) and Fourier transform Raman spectroscopy (FT-Raman). The Cu(4)Zn(3)MT-III contains 26-28% beta-turns and half-turns, 13-14% 3(10)-helices, 47-49% random coils, and 11-12% beta-extended chains. The structural comparison of porcine brain Cu(4)Zn(3)MT-III with rabbit liver Cd(5)Zn(2)MT-I (II) and Zn(7)MT-I shows that the contents of the random coil structure are obviously increased. The results indicate that the insert of an acidic hexapeptide in the alpha domain of Cu(4)Zn(3)MT-III possibly forms an alpha helix. However, because the bands assigned to the alpha-helix and random coil structures are overlapped in the spectra, the content of random coil structures in Cu(4)Zn(3)MT-III is therefore higher than those in Cd(5)Zn(2)MT-I, Cd(5)Zn(2)MT-II, and Zn(7)MT-I. PMID:12209458

Shi, Yan-Bo; Fang, Jiang-Lin; Liu, Xiao-Yu; Du, Liang; Tang, Wen-Xia

2002-10-15

356

Data reconstructing for windowing broom Fourier transform imaging spectrometers based on multi-core techniques  

NASA Astrophysics Data System (ADS)

The windowing broom Fourier transform imaging spectrometer, based on space-time modulation, has the characteristics of high luminous flux, static interference part etc. However, the large amount of raw data and the data reconstruction increase the difficulty of the whole data processing and extend the computing time. In this paper, a parallel calculation algorithm for reconstruction of raw data is proposed. The proposed algorithm is achieved by using Task Parallel Library (TPL), which is provided by .NET framework, and a visualized processing system is further established. A set of data collected from a windowing broom Fourier transform imaging spectrometer is processed using both the proposed method and the ordinary serial algorithm. The scalability of this presented algorithm is verified by employing it on computers with different number of cores. The experimental results show that, compared to the serial algorithm, the proposed method can greatly speed up the processing with the same hardware condition, and it also has ideal scalability with different hardware.

Dong, Zhi-gang; Liao, Ning-fang; Qu, Liang; Lv, Hang

2013-08-01

357

Gaseous effluent monitoring and identification using an imaging Fourier transform spectrometer  

SciTech Connect

We are developing an imaging Fourier transform spectrometer for chemical effluent monitoring. The system consists of a 2-D infrared imaging array in the focal plane of a Michelson interferometer. Individual images are coordinated with the positioning of a moving mirror in the Michelson interferometer. A three dimensional data cube with two spatial dimensions and one interferogram dimension is then Fourier transformed to produce a hyperspectral data cube with one spectral dimension and two spatial dimensions. The spectral range of the instrument is determined by the choice of optical components and the spectral range of the focal plane array. Measurements in the near UV, visible, near IR, and mid-IR ranges are possible with the existing instrument. Gaseous effluent monitoring and identification measurements will be primarily in the ``fingerprint`` region of the spectrum, ({lambda} = 8 to 12 {mu}m). Initial measurements of effluent using this imaging interferometer in the mid-IR will be presented.

Carter, M.R.; Bennett, C.L.; Fields, D.J.; Hernandez, J.

1993-10-01

358

Mix ratio measurements of pozzolanic blends by Fourier transform infrared-attenuated total reflectance method  

SciTech Connect

The disposal of low-level radioactive liquid wastes at the Hanford Site near Richland, Washington, involves mixing the wastes with pozzolanic grout-forming solid blends. Checking the quality of each blend component and its mix ratio will ensure processibility of the blend and the long-term performance of the resulting waste grout. In earlier work at Hanford laboratories, Fourier transform infrared-transmission method (FTIR-TR) using KBr pellet was applied successfully in the analysis of blends consisting of cement, fly ash, and clays. This method involves time-consuming sample preparation resulting in slow turnaround for repetitive sampling. Because reflection methods do not require elaborate sample preparation, they have the potential to reduce turnaround analysis time. Neat samples may be examined making these methods attractive for quality control. This study investigates the capability of Fourier transform infrared-attenuated total reflectance method (FTIR-ATR) to analyze pozzolanic blends.

Rebagay, T.V.; Dodd, D.A.

1992-07-01

359

Diffractive imaging analysis of large-aperture segmented telescope based on partial Fourier transform  

NASA Astrophysics Data System (ADS)

Large-aperture segmented primary mirror will be widely used in next-generation space-based and ground-based telescopes. The effects of intersegment gaps, obstructions, position and figure errors of segments, which are all involved in the pupil plane, on the image quality metric should be analyzed using diffractive imaging theory. Traditional Fast Fourier Transform (FFT) method is very time-consuming and costs a lot of memory especially in dealing with large pupil-sampling matrix. A Partial Fourier Transform (PFT) method is first proposed to substantially speed up the computation and reduce memory usage for diffractive imaging analysis. Diffraction effects of a 6-meter segmented mirror including 18 hexagonal segments are simulated and analyzed using PFT method. The influence of intersegment gaps and position errors of segments on Strehl ratio is quantitatively analyzed by computing the Point Spread Function (PSF). By comparing simulation results with theoretical results, the correctness and feasibility of PFT method is confirmed.

Dong, Bing; Qin, Shun; Hu, Xinqi

2013-09-01

360

Research on projection grating pitch in GTAW surface sensing based on Fourier transform profilometry  

NASA Astrophysics Data System (ADS)

Selecting an appropriate pitch is one of the most important aspects to ensure the system measurement range and precision in grating projection principle of 3D profile measurement while the Fourier transform frequency spectrum is separated completely. According to the concept of the equivalent wavelength, the basic requirement for measurement system and the selection of projection grating pitch are discussed in this paper to avoid shadows and frequency spectrum alias in a crossed-optical-axes system in Fourier Transform Profilometry (FTP). The influence of CCD sampling to the FTP is also discussed to obtain CCD sampling condition. When the CCD sampling frequency is unchanged, it is necessary to reduce the grating frequency which means to increase the grating pitch to satisfy the sampling condition. Finally, the range of the grating pitch is determined, and the optimal grating pitch is obtained after the experiments.

Hu, Xian; Liu, Nansheng; Ai, Xiaopu; Wei, Yiqing; Liu, Xiaorui; Wei, Sheng

2009-11-01

361

Fatal extensive bone cement embolism: histological findings confirmed by Fourier transform infrared spectroscopy.  

PubMed

We herein report the first case of fatal extensive bone cement embolism appearing in pulmonary arterioles following surgical vertebral screw augmentation, which histological evidence of bone cement emboli was confirmed by Fourier transform infrared spectroscopy. A 47-year-old woman has accepted multilevel spine fusion and pedicle screw augmentation with totally 4 ml bone cement infusion. She suddenly developed low blood pressure, dyspnoea, and unconsciousness approximately 1 h post anaesthetic recovery, and then she was dead. It was shown both lungs were edematous in autopsy, and bluish emboli were appeared in extensive pulmonary arterioles in H&E stained sections. Negative information was shown in Molybdenum target X-ray imaging, but the emboli were confirmed to be PMMA bone cement by Fourier transform infrared spectroscopy. The present case indicated it might be effective to confirm the dubious trace component in histology by FTIR. PMID:23821787

Zheng, Na; Liang, Man; Zhang, Hai Dong; Zhu, Shao Hua; Yang, Tian Tong; Zhuo, Luo; Wang, Gui Feng; Liu, Hong Xia; Liu, Liang

2013-04-19

362

Image encryption based on extended fractional Fourier transform and digital holography technique  

NASA Astrophysics Data System (ADS)

We present a new optical image encryption algorithm that is based on extended fractional Fourier transform (FRT) and digital holography technique. We can perform the encryption and decryption with more parameters compared with earlier similar methods in FRT domain. In the extended FRT encryption system, the input data to be encrypted is extended fractional Fourier transformed two times and random phase mask is placed at the output plane of the first extended FRT. By use of an interference with a wave from another random phase mask, the encrypted data is stored as a digital hologram. The data retrieval is operated by all-digital means. Computer simulations are presented to verify its validity and efficiency.

Wang, Xiaogang; Zhao, Daomu; Chen, Linfei

2006-04-01

363

Absolute line intensities in the ? by laser photoacoustic spectroscopy and Fourier transform spectroscopy  

NASA Astrophysics Data System (ADS)

Line intensities and self-broadening coefficients in the ?1 + 3?3 band of 12C2H2 near 0.8 µm at room temperature were measured by means of both laser photoacoustic and Fourier transform spectroscopy. An experimental protocol has been developed to obtain absolute intensities from the photoacoustic measurements. Namely, the spectrometer was calibrated using water vapour line intensities available in Hitran 1996 [L. S. Rothman et al. (1998) J. quant. Spectrosc. Radiat. Transfer, 60, 665-710]. These photoacoustic line intensities were found to be on average 5% higher than corresponding measurements performed using Fourier transform spectroscopy, the accuracy of the latter being estimated to better than 4%. The accuracy of the photoacoustic intensities is discussed. Previous results from the literature [F. Herregodts, D. Hurtmans, J. Vander Auwera, and M. Herman (1999) J. chem. Phys., 111, 7954-7960] are revised.

Herregodts, F.; Kerrinckx, E.; Huet, T. R.; Vander Auwera, J.

364

Imaging Fourier transform endospectroscopy for in vivo and in situ multispectral imaging.  

PubMed

We report the design and implementation of a multispectral imaging Fourier transform endospectroscopy (IFTES) system. The IFTES system employs a flexible fiber bundle catheter coupled to a home-built imaging Fourier transform spectroscope. The instrument enables the performance of non- or minimally invasive subsurface imaging and multispectral imaging at the cellular level in vivo and in situ. A maximum spectral resolution of 0.2 nm at 632.8 nm and a lateral resolution of 4.4 ?m were proved. Preliminary results of a standard resolution target, ex-vivo small animal tissue, single wavelength laser, fluorescence solution, in-vivo mouse skin, microspheres mixture, and in-vivo transgenic mouse brain were given to demonstrate the potential of the technique. PMID:23188298

Zhang, Hongming; Yuan, Jing; Fu, Ling

2012-10-01

365

Fourier-transform mass spectrometry of large molecules by electrospray ionization.  

PubMed Central

The multiply charged ions produced by electrospray ionization of peptides of molecular masses up to 29 kDa have been successfully introduced into a Fourier transform mass spectrometer of unique capabilities for tandem mass spectrometry, large ion dissociation, and resolution. Electrospray ionization places an unusually high number of charges on a peptide yielding mass/charge (m/z) values of 600-1500; in this range at normal operating pressures (approximately 10(-9) torr; 1 torr = 133.3 Pa) Fourier-transform mass spectrometry resolving power is greater than 100,000. Although only 10(-7) torr pressure has been obtained with the initial interface, the resulting resolving power of 5000 makes possible the resolution of isotopic peaks of multiply charged ions. Mass measuring accuracies of a few daltons for molecular masses up to 17 kDa have also been achieved.

Henry, K D; Williams, E R; Wang, B H; McLafferty, F W; Shabanowitz, J; Hunt, D F

1989-01-01

366

Optical imaging process based on two-dimensional Fourier transform for synthetic aperture imaging ladar  

NASA Astrophysics Data System (ADS)

The synthetic aperture imaging ladar (SAIL) systems typically generate large amounts of data difficult to compress with digital method. This paper presents an optical SAIL processor based on compensation of quadratic phase of echo in azimuth direction and two dimensional Fourier transform. The optical processor mainly consists of one phase-only liquid crystal spatial modulator(LCSLM) to load the phase data of target echo and one cylindrical lens to compensate the quadratic phase and one spherical lens to fulfill the task of two dimensional Fourier transform. We show the imaging processing result of practical target echo obtained by a synthetic aperture imaging ladar demonstrator. The optical processor is compact and lightweight and could provide inherent parallel and the speed-of-light computing capability, it has a promising application future especially in onboard and satellite borne SAIL systems.

Sun, Zhiwei; Zhi, Ya'nan; Liu, Liren; Sun, Jianfeng; Zhou, Yu; Hou, Peipei

2013-09-01

367

Simulation of micromechanical behavior of polycrystals: finite elements vs. fast Fourier transforms  

SciTech Connect

In this work, we compare finite element and fast Fourier transform approaches for the prediction of micromechanical behavior of polycrystals. Both approaches are full-field approaches and use the same visco-plastic single crystal constitutive law. We investigate the texture and the heterogeneity of the inter- and intragranular, stress and strain fields obtained from the two models. Additionally, we also look into their computational performance. Two cases - rolling of aluminium and wire drawing of tungsten - are used to evaluate the predictions of the two mode1s. Results from both the models are similar, when large grain distortions do not occur in the polycrystal. The finite element simulations were found to be highly computationally intensive, in comparison to the fast Fourier transform simulations.

Lebensohn, Ricardo A [Los Alamos National Laboratory; Prakash, Arun [IWM FREIBURG

2009-01-01

368

The X1?g+ ground state of Mg2 studied by Fourier-transform spectroscopy  

NASA Astrophysics Data System (ADS)

The A1?u+ - X1?g+ UV spectrum of Mg2 has been investigated with high resolution Fourier-transform spectroscopy. Mg2 vapor was created in a heat pipe. Various spectroscopic methods have been employed, such as conventional absorption spectroscopy with light from a broad band lamp and laser-induced fluorescence. The high resolution of the Fourier-transform spectrometer, together with computer aided evaluation methods of the spectra, yields precise transition frequencies. The new data and data available from earlier investigations are applied in direct potential fits of lower and upper electronic states. Various representations of potential energy curves for the ground state X1?g+ have been employed and their benefits in terms of smallest number of parameters are discussed. Scattering lengths are derived for the homonuclear isotopologues and compared with previous results.

Knöckel, H.; Rühmann, S.; Tiemann, E.

2013-03-01

369

The X(1)?g(+) ground state of Mg2 studied by Fourier-transform spectroscopy.  

PubMed

The A(1)?u(+) - X(1)?g(+) UV spectrum of Mg2 has been investigated with high resolution Fourier-transform spectroscopy. Mg2 vapor was created in a heat pipe. Various spectroscopic methods have been employed, such as conventional absorption spectroscopy with light from a broad band lamp and laser-induced fluorescence. The high resolution of the Fourier-transform spectrometer, together with computer aided evaluation methods of the spectra, yields precise transition frequencies. The new data and data available from earlier investigations are applied in direct potential fits of lower and upper electronic states. Various representations of potential energy curves for the ground state X(1)?g(+) have been employed and their benefits in terms of smallest number of parameters are discussed. Scattering lengths are derived for the homonuclear isotopologues and compared with previous results. PMID:23485290

Knöckel, H; Rühmann, S; Tiemann, E

2013-03-01

370

Determination of phospholipids in vegetable oil by fourier transform infrared spectroscopy  

Microsoft Academic Search

A method was developed to determine the total phospholipid content in vegetable oil by Fourier transform infrared spectroscopy\\u000a (FTIR). Calibration curves of I-?-phosphatidylcholine (PC), I-?-phosphatidylethanolamine (PE), and I-?-phosphatidylinositol\\u000a (PI) in hexane were generated at different concentrations. The optimal phospholipid absorption bands between 1200–970 cm?1 were identified and used for quantitative determination. High R\\u000a 2?0.968 were observed between band areas and

J. M. Nzai; A. Proctor

1998-01-01

371

Fourier series of functions whose Hankel transform is supported on [0, 1  

Microsoft Academic Search

LetJµ denote the Bessel function of order µ. For a>-1, the system x-a\\/2-1\\/2Ja+2n+1(x1\\/2, n=0, 1, 2,..., is orthogonal onL2((0, 8),xadx). In this paper we study the mean convergence of Fourier series with respect to this system for functions whose Hankel transform is supported on [0, 1].

Juan L. Varona

1994-01-01

372

Towards high-throughput metabolomics using ultrahigh-field Fourier transform ion cyclotron resonance mass spectrometry  

Microsoft Academic Search

With unmatched mass resolution, mass accuracy, and exceptional detection sensitivity, Fourier Transform Ion Cyclotron Resonance\\u000a Mass Spectrometry (FTICR-MS) has the potential to be a powerful new technique for high-throughput metabolomic analysis. In\\u000a this study, we examine the properties of an ultrahigh-field 12-Tesla (12T) FTICR-MS for the identification and absolute quantitation\\u000a of human plasma metabolites, and for the untargeted metabolic fingerprinting

Jun Han; Ryan M. Danell; Jayanti R. Patel; Dmitry R. Gumerov; Cameron O. Scarlett; J. Paul Speir; Carol E. Parker; Ivan Rusyn; Steven Zeisel; Christoph H. Borchers

2008-01-01

373

Microcomputer-based instrumentation for multi-frequency Fourier transform alternating current (admittance and impedance) voltammetry  

Microsoft Academic Search

Microcomputer-based instrumentation has been developed which enables high quality Fourier transform alternating current admittance and impedance voltammograms to be obtained over a wide range of frequencies and d.c. potentials. A carefully chosen phase-optimised small amplitude alternating potential waveform containing sets of frequencies which avoid harmonic or intermodular interference are periodically superimposed onto a staircase d.c. ramped voltage. Considerable versatility is

Jeno Házì; Darrell M. Elton; W. Alexander Czerwinski; Jörg Schiewe; Victoria A. Vicente-Beckett; Alan M. Bond

1997-01-01

374

Measuring residual stress of anisotropic thin film by fast Fourier transform.  

PubMed

A new method for the measurement of anisotropic stress in thin films based on 2-D fast Fourier transform (FFT) is presented. A modified Twyman-Green interferometer was used for surface topography measurement. A fringe normalization technique was also used to improve the phase extraction technique efficiently. The measurement of anisotropic stress in obliquely deposited MgF(2) thin film was demonstrated. PMID:20721050

Tien, Chuen-Lin; Zeng, Hung-Da

2010-08-01

375

On a Relative Fourier–Mukai Transform on Genus One Fibrations  

Microsoft Academic Search

We study relative Fourier–Mukai transforms on genus one fibrations with section, allowing explicitly the total space of the fibration to be singular and non-projective. Grothendieck duality is used to prove a skew–commutativity relation between this equivalence of categories and certain duality functors. We use our results to explicitly construct examples of semi-stable sheaves on degenerating families of elliptic curves.

Igor Burban; Bernd Kreussler

2006-01-01

376

Security Evaluation of a DPA-Resistant S-Box Based on the Fourier Transform  

Microsoft Academic Search

At CHES 2006, Prouff et al. proposed a novel S-box calculation based on the discrete Fourier transform as a first-order DPA countermeasure. At CHES 2008,\\u000a Coron et al. showed that the original countermeasure can be broken by first-order DPA due to a biased mask and they proposed an improved\\u000a algorithm. This paper shows that there is still a flaw in the

Yang Li; Kazuo Sakiyama; Shin-ichi Kawamura; Yuichi Komano; Kazuo Ohta

2009-01-01

377

Genetic programming of polynomial harmonic models using the discrete Fourier transform  

Microsoft Academic Search

The paper presents a genetic programming (GP) system that evolves polynomial harmonic networks. The hybrid tree-structured network representation suggests that terminal harmonics with non-multiple frequencies may enter polynomial function nodes as variables. The harmonics with non-multiple, irregular frequencies are derived analytically using the discrete Fourier transform. The development of polynomial harmonic GP includes also design of a regularized statistical fitness

Nikolay Nikolaev; Hitoshi Iba

2001-01-01

378

Chemically functionalized carbon nanotubes and their characterization using thermogravimetric analysis, fourier transform infrared, and raman spectroscopy  

Microsoft Academic Search

This article reports key findings on the chemical functionalization of carbon nanotubes (CNT). The functionalization of chemical\\u000a vapor-deposited CNT was carried out by treating tubes with polyvinyl alcohol through ultrasonication in water with the aid\\u000a of a surfactant. The surfactant is expected to promote the unbundling of aggregated CNT. The characterization of functionalized\\u000a samples using thermogravimetric analysis, Fourier transform infrared

E. Titus; N. Ali; G. Cabral; J. Gracio; P. Ramesh Babu; M. J. Jackson

2006-01-01

379

First signal on the cryogenic fourier-transform ion cyclotron resonance mass spectrometer  

Microsoft Academic Search

The construction and achievement of the first signal on a cryogenic Fourier-transform ion cyclotron resonance mass spectrometer\\u000a (FTICR-MS) are reported here, demonstrating proof-of-concept of this new instrument design. Building the FTICR cell into the\\u000a cold bore of a superconducting magnet provided advantages over conventional warm bore design. At 4.2 K, the vacuum system\\u000a cryopumps itself, thus removing the requirement for

Cheng Lin; Raman Mathur; Kostantin Aizikov; Peter B. O’Connor

2007-01-01

380

Optical design of a miniature Fourier transform lens system for a hybrid digital-optical correlator  

NASA Astrophysics Data System (ADS)

The availability of high resolution spatial light modulators (SLMs) and modern digital signal processors (DSPs) allows a convenient hybridization of digital and optical image processing to produce a small and compact correlator system. The hybridization allows the optical Fourier transform lens system for a correlator to be compact, such that it will fit inside a conventional PC. We describe the design of the optical system.

Birch, Philip M.; Li, Gongde; Claret-Tournier, Frederic; Young, Rupert C.; Budgett, David M.; Chatwin, Christopher R.

2002-07-01

381

Characterization of an RNA bulge structure by Fourier transform infrared spectroscopy  

Microsoft Academic Search

There may be several advantages associated with an antisense oligonucleotide that induces a bulged structure into its RNA target molecule. Many structures of RNA bulges are elucidated from single-stranded RNA models. However, a two-component system is the minimum requirement for a realistic antisense model. We have used Fourier transform infrared spectroscopy to investigate a single-stranded RNA oligonucleotide with known NMR

Martina Banyay; Jessica Sandbrink; Roger Strömberg; Astrid Gräslund

2004-01-01

382

Elastic electron scattering from state-selected molecules. II. Fourier transforms  

Microsoft Academic Search

The elastic, electron scattering cross sections for molecules in particular vibration-rotation states contain two-dimensional information if there is a well-defined quantization axis. In addition to deducing that information by representing the scattered intensity by a model, it is possible to reconstruct a real space image of the molecule by means of a special two-dimensional Fourier transform that is unique to

D. A. Kohl; E. J. Shipsey

1992-01-01

383

Fourier transform infrared spectroscopic study of the carbonate ions in bone mineral during aging  

Microsoft Academic Search

Summary  The environment of CO3\\u000a 2? ions in the bone mineral of chickens of different ages and in bone fractions of different density have been investigated\\u000a by resolution-enhanced Fourier Transform Infrared (FTIR) Spectroscopy. Three carbonate bands appear in thev\\u000a 2 CO3 domain at 878, 871, and 866 cm?1, which may be assigned to three different locations of the ion in the

C. Rey; V. Renugopalakrishman; B. Collins; Melvin J. Glimcher

1991-01-01

384

Nontargeted metabolome analysis by use of Fourier transform ion cyclotron mass spectrometry  

Microsoft Academic Search

Advanced functional genomic tools now allow the parallel and high-throughput analyses of gene and protein expression. Although this information is crucial to our understanding of gene function, it offers insufficient insight into phenotypic changes associated with metabolism. Here we introduce a high-capacity Fourier Transform Ion Cyclotron Mass Spectrometry (FTMS)¿based method, capable of nontargeted metabolic analysis and suitable for rapid screening

Asaph Aharoni; Vos de C. H; C. A. Maliepaard; G. Kruppa; R. J. Bino; D. Goodenough; Dayan B. Goodenowe

2002-01-01

385

Fractional Fourier transform for elliptical Gaussian beam in spatial-frequency domain  

NASA Astrophysics Data System (ADS)

The fractional Fourier transform (FRT) is applied to elliptical Gaussian beam (EGB) in spatial-frequency domain. An equivalent tensor ABCD law for the FRT of EGB is derived in terms of the tensor method. The connection between the FRT formula and the generalized Collins formula in spatial-frequency domain is discussed. The derived formulae provide a powerful tool for analyzing and calculating the FRT of EGB in spatial-frequency domain. An application example is provided.

Cai, Yangjian; Lin, Qiang

386

Automated detection of sulfur dioxide in stack emissions by passive Fourier transform infrared spectrometry  

Microsoft Academic Search

Passive Fourier transform infrared (FT-IR) spectrometry is used in the automated qualitative determination of sulfur dioxide (SO2) in a stack monitoring application. Digital filtering and pattern recognition techniques are optimized and applied to short sections of interferograms in a methodology developed to minimize effects of background variation. Two data sets are investigated that were collected with four similarly configured FT-IR

Frederick W Koehler; Gary W Small; Roger J Combs; Robert B Knapp; Robert T Kroutil

2001-01-01

387

Measurement of sulfur dioxide with the differential optical absorption technique combined with Fourier transformation  

Microsoft Academic Search

The concentration of sulfur dioxide has been measured in the ultraviolet spectral range with a combination of the differential optical absorption technique and Fourier transformation. Measurements have been made with a pathlength of two meters and a measuring time of one minute. Sulfur dioxide levels of less than 0.1 ppm (volume) were assessed with a measurement uncertainty of [plus minus]0.03

L. Axelsson; A. Lauber

1992-01-01

388

Submillimeter FourierTransform Spectrometer Measurements of Atmospheric Opacity Above Mauna Kea  

Microsoft Academic Search

We present accurately calibrated submillimeter atmospheric transmission spectra obtained with a Fourier-transform spectrometer at the Caltech Submillimeter Observatory on Mauna Kea, Hawaii. These measurements cover the 0.9 - 0.3-mm wavelength range and are the first in a series aimed at defining the terrestrial long-wave atmospheric transmission curve. The 4.1-km altitude of the Mauna Kea site provides access to extremely low

E. Serabyn; E. W. Weisstein; D. C. Lis; J. R. Pardo

1998-01-01

389

Polarized Single-Crystal FourierTransform Infrared Microscopy of Ouray Dickite and Keokuk Kaolinite  

Microsoft Academic Search

Single-crystal Fourier-transform infrared (FTIR) spectra of Keokuk kaolinite and Ouray dickite were obtained with an FTIR microscope. Although numerous IR, FTIR, and Raman spectra of poly- crystalline kaolinite and dickite can be found in the literature, the present data represent the first reported single-crystal vibrational spectra for these clay minerals. The orientation of the crystallographic axes of dickite was determined

C. T. Johnston; S. F. AGNEW; D. L. BISH

1990-01-01

390

In situ semiconductor materials characterization by emission Fourier transform infrared spectroscopy  

Microsoft Academic Search

The results of a novel emission Fourier transform infrared (E\\/FT-IR) spectrometer for in-situ characterization of semiconductor materials is presented. For the experiments, the wafers were heated and the infrared emission profiles from the substrates were collected by a standard FT-IR spectrometer. Differences in the emission spectra from different substrates are explained through correlation to the optical properties of the corresponding

Zhen-Hong Zhou; Senja Compton; Isabel Yang; Rafael Reif

1994-01-01

391

The characterisation of pluripotent and multipotent stem cells using fourier transform infrared microspectroscopy.  

PubMed

Fourier transform infrared (FTIR) microspectroscopy shows potential as a benign, objective and rapid tool to screen pluripotent and multipotent stem cells for clinical use. It offers a new experimental approach that provides a holistic measurement of macromolecular composition such that a signature representing the internal cellular phenotype is obtained. The use of this technique therefore contributes information that is complementary to that acquired by conventional genetic and immunohistochemical methods. PMID:24065090

Cao, Julie; Ng, Elizabeth S; McNaughton, Donald; Stanley, Edouard G; Elefanty, Andrew G; Tobin, Mark J; Heraud, Philip

2013-08-26

392

The Fourier transform of a function related to the plasma dispersion function  

Microsoft Academic Search

The Fourier transform F of the function Z (omega\\/modulus KV)\\/modulus KV is considered in reference to the theory of linearized waves in a hot plasma having a Maxwellian velocity distribution. The term Z is the so-called plasma dispersion function, omega and k are the frequency and wave number of a wave, and v is the thermal velocity of the particle.

A. E. P. M. Abels-Vanmaanen

1980-01-01

393

Achromatic or quasi-color Fourier transform hologram and optical diffraction images  

NASA Astrophysics Data System (ADS)

A binary computer generated hologram (CGH) and a Fourier Transform hologram (FTH) with gray level/quasi-colors are similar to all appearance in the structure of hologram cell. However, they are wholly different in display techniques by the use of gray level or quasi-colors. It is possible to directly take a picture of reduced FTH, i.e., a kind of positive and negative transparency, displayed on a standard color LCD/CRT using a negative film with high contrast.

Iizuka, Masayuki; Ookuma, Yoshio; Nakashima, Yoshio

2001-06-01

394

An introduction to combined Fourier-wavelet transform and its application to convectively coupled equatorial waves  

NASA Astrophysics Data System (ADS)

Convectively coupled equatorial waves (CCEWs) are major sources of tropical day-to-day variability. The majority of CCEWs-related studies for the past decade or so have based their analyses, in one form or another, on the Fourier-based space-time spectral analysis method developed by Wheeler and Kiladis (WK). Like other atmospheric and oceanic phenomena, however, CCEWs exhibit pronounced nonstationarity, which the conventional Fourier-based method has difficulty elucidating. The purpose of this study is to introduce an analysis method that is able to describe the time-varying spectral features of CCEWs. The method is based on a transform, referred to as the combined Fourier-wavelet transform (CFWT), defined as a combination of the Fourier transform in space (longitude) and wavelet transform in time, providing an instantaneous space-time spectrum at any given time. The elaboration made on how to display the CFWT spectrum in a manner analogous to the conventional method (i.e., as a function of zonal wavenumber and frequency) and how to estimate the background noise spectrum renders the method more practically feasible. As a practical example, this study analyzes 3-hourly cloud archive user service (CLAUS) cloudiness data for 23 years. The CFWT and WK methods exhibit a remarkable level of agreement in the distributions of climatological-mean space-time spectra over a wide range of space-time scales ranging in time from several hours to several tens of days, indicating the instantaneous CFWT spectrum provides a reasonable snapshot. The usefulness of the capability to localize space-time spectra in time is demonstrated through examinations of the annual cycle, interannual variability, and a case study.

Kikuchi, Kazuyoshi

2013-09-01

395

Determination of anisidine value in thermally oxidized palm olein by fourier transform infrared spectroscopy  

Microsoft Academic Search

Fourier transform infrared (FTIR) spectroscopy with transmission cell is described to predict anisidine value of palm olein.\\u000a The calibration set was prepared by mixing the thermally oxidized palm olein and the unoxidized palm olein with certain ratios\\u000a (w\\/w) covering a wide range of anisidine values. A partial least square (PLS) regression technique was employed to construct\\u000a a calibration model. This

Y. B. Che Man; G. Setiowaty

1999-01-01

396

Effect of the fringe visibility on spectrum SNR of Fourier transform imaging spectrometer  

NASA Astrophysics Data System (ADS)

The principle of Fourier transform spectrometer is based on the relationship of Fourier-Transform between interferogram and spectrum. The spectral information of Fourier transform imaging spectrometer (FTIS) reconstructed from raw interferogram by data processing. So there are two kinds of signal-to-noise ratio (SNR) to evaluate instrument performance, one regarding interferogram and the other regarding reconstructed spectrum. Because the raw interferogram is intuitive, the interferogram SNR is studied usually. On the contrary, the spectrum SNR is studied less because of the complexity of the data processing from interferogram to spectrum. The research about the effect of the interference fringe visibility on the spectrum SNR is especially few. This paper present a research work on the relations between the interference fringe visibility and the spectrum SNR. Firstly, the reduction of fringe visibility caused by imaging lens defocus was analyzed. Secondly, the changes of the average spectrum signal and noise caused by the reduction of fringe visibility were calculated. For average spectrum signal, the math deductions are done base on Fourier transform theory. The average noise with different input signal optic-electrons number are simulated. the results show that the average spectrum signal is directly proportional to the fringe visibility, and the effect of fringe visibility on the noise related to signal can be ignorable. Finally, In order to demonstrate above results, the imaging experiment was done with white-light source, using LASIS (Large aperture static imaging spectrometer) based on Sagnac Interferometer. The average spectrum SNRs under different fringe visibility are calculated and analyzed. The experimental results show that: the average spectrum SNRs increase from 42.7 to 62.4.along with the fringe visibility increasing from 0.5051 to 0.687. the reconstructed spectrum SNR is directly proportional to the fringe visibility. As a result, the interferogram fringe visibility can be used to estimate the reconstructed spectrum SNR, and evaluate the performance of FTIS before data processing.

Wang, Shuang; Bin, Xiangli; Jing, Juanjuan; Pi, Haifeng

2013-08-01

397

Very low H–O–H bending frequencies. IV. Fourier transform infrared spectra of synthetic dittmarite  

Microsoft Academic Search

The Fourier transform infrared spectra of MgNH4PO4·H2O (the synthetic analogue of the mineral dittmarite) and of a series of its partially deuterated analogues have been studied as a part of our continuous work on compounds exhibiting very low water bending frequencies. Although, the presence of ammonium bands makes the assignments in this case more difficult than for the potassium analogues,

Bojan Šoptrajanov; Viktor Stefov; Igor Kuzmanovski; Gligor Jovanovski; H. Dieter Lutz; Bernward Engelen

2002-01-01

398

Non-destructive evaluation (NDE) using multi-aperture DSPI system and fast Fourier transform method  

Microsoft Academic Search

Digital speckle pattern interferometry (DSPI) and digital shearography (DS) are two independent whole-field non-contacting optical methods for nondestructive flaw detection and precision measurements. A multi-aperture arrangement in front the imaging lens provides the grid structure within the speckles to yield desired diffraction halos at the Fourier transform plane. A three aperture arrangement in front of the imaging system is proposed

Basanta Bhaduri; N. Krishna Mohan; M. P. Kothiyal

2007-01-01

399

A rapid method for detecting bacterial polyhydroxyalkanoates in intact cells by Fourier transform infrared spectroscopy  

Microsoft Academic Search

Polyhydroxyalkanoates (PHA) are synthesized by many bacteria as inclusion bodies, and their biodegradability and structural\\u000a diversity have been studied with a view to their potential application as biodegradable materials. In this paper, Fourier-transform\\u000a infrared spectroscopy (FT-IR) was used to carry out rapid qualitative analysis of PHA in intact bacterial cells. The FT-IR\\u000a spectra of pure PHA containing short-chain-length monomers, such

K. Hong; S. Sun; W. Tian; G. Q. Chen; W. Huang

1999-01-01

400

Degeneration of solventogenic Clostridium strains monitored by Fourier transform infrared spectroscopy of bacterial cells  

Microsoft Academic Search

  Strain degeneration in solventogenic clostridia is a known problem in the technical acetone–butanol fermentation bioprocess,\\u000a especially in the continuous process mode. Clostridial strain degeneration was studied by Fourier transform infrared (FT-IR)\\u000a spectroscopy of the bacterial cells. Degenerative variant formation in two strains, Clostridium beijerinckii NCIMB 8052 and Clostridium species AA332, was detected spectroscopically. Colonies on solid media were sampled, or

KC Schuster; R Goodacre; JR Gapes; M Young

2001-01-01

401

FOURIER-TRANSFORM ANALYSIS OF NORMAL PHOTOELECTRON DIFFRACTION DATA FOR SURFACE-STRUCTURE DETERMINATION  

SciTech Connect

A direct method for surface-structure determination from normal emission photoelectron diffraction (NPD) data is presented. Fourier transforms of the calculated NPD intensities yield peaks at adsorbate-substrate normal interlayer distances. Applications are demonstrated using theoretical NPD curves for the Se/Ni system calculated by dynamical theory. These results show that interplanar spacings between the overlayer and as many as four substrate layers could be determined with an accuracy of better than 3%.

Hussain, Z.; Shirley, D. A.; Li, C. H.; Tong, S. Y.

1981-05-01

402

FOURIER-TRANSFORM ANALYSIS OF NORMAL PHOTOELECTRON DIFFRACTION DATA FOR SURFACE-STRUCTURE DETERMINATION  

SciTech Connect

A direct method for surface-structure determination from normal emission photoelectron diffraction (NPD) data is presented. Fourier transforms of the calculated NPD intensities yield peaks at adsorbate-substrate normal interlayer distances. Applications are demonstrated using theoretical NPD curves for the Se/Ni system calculated by dynamical theory. These results show that interplanar spacings between the overlayer and as many as four substrate layers could be determined with an accuracy of better than 2%.

Hussain, Z.; Shirley, D. A.; Li, C. H.; Tong, S. Y.

1980-10-01

403

Optical phase retrieval by phase-space tomography and fractional-order Fourier transforms  

Microsoft Academic Search

Phase-space tomography is experimentally demonstrated for the determination of the spatially varying amplitude and phase of a quasi-monochromatic optical f ield by measurements of intensity only. Both fully and partially coherent sources are characterized. The method, which makes use of the fractional-order Fourier transform, also yields the Wigner distribution of the f ield and works in one or two dimensions.

D. F. McAlister; M. Beck; L. Clarke; A. Mayer; M. G. Raymer

1995-01-01

404

An in situ Fourier transform infrared spectroelectrochemical study on ethanol electrooxidation on Pd in alkaline solution  

Microsoft Academic Search

The mechanism of ethanol electrooxidation on a palladium electrode in alkaline solution (from 0.01 to 5M NaOH) has been investigated by cyclic voltammetry and in situ Fourier transform infrared spectroelectrochemistry. The electrode performance has been found to depend on the pH of the fuel solution. The best performance was observed in 1M NaOH solution (pH=14), while the electrochemical activity decreased

Xiang Fang; Lianqin Wang; Pei Kang Shen; Guofeng Cui; Claudio Bianchini

2010-01-01

405

A 64-point Fourier transform chip for video motion compensation using phase correlation  

Microsoft Academic Search

Details of a new low power fast Fourier transform (FFT) processor for use in digital television applications are presented. This has been fabricated using a 0.6-?m CMOS technology and can perform a 64 point complex forward or inverse FFT on real-time video at up to 18 Megasamples per second. It comprises 0.5 million transistors in a die area of 7.8×8

Colin Chiu; Wing Hui; Tiong Jiu Ding; J. V. McCanny

1996-01-01

406

Fourier Transform Vibrational Spectroscopy of Pure Carbon and Silicon-Carbon Clusters  

Microsoft Academic Search

Fourier transform infrared studies of pure carbon and silicon-carbon clusters produced by vacuum ultraviolet (VUV) photolysis and by the newly developed method of laser evaporation have resulted in the identification of new vibrational information for the C_4, SiC_4 and C_9 clusters. For the first time, the far-infrared bending vibration of C_4 has been observed at a frequency of 172.4 cm^{-1}

Paul Andrew Withey

1993-01-01

407

Fourier transform infrared spectroscopy techniques for the analysis of drugs of abuse  

Microsoft Academic Search

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

Kathryn S. Kalasinsky; Barry K. Levine; Michael L. Smith; Joseph J. Magluilo; Teresa Schaefer

1994-01-01

408

Dispersive Fourier transform spectroscopy in the visible of absorbing gases and vapours  

Microsoft Academic Search

Dispersive Fourier transform spectroscopy in the visible (DFTS-VIS) is used to study the complex refractive index n?(?, T, ?) of equilibrium mixtures of NO2N2O4 near room temperature, as well as the dispersion of n?(?, T, ?) of cadmium vapour up to temperatures of 1052K. In addition, the dispersion of the complex mean dipole polarizability \\\\?ga(?) is obtained from these measurements.

D. Goebel; U. Hohm; K. Kerl

1995-01-01

409

The Characterisation of Pluripotent and Multipotent Stem Cells Using Fourier Transform Infrared Microspectroscopy  

PubMed Central

Fourier transform infrared (FTIR) microspectroscopy shows potential as a benign, objective and rapid tool to screen pluripotent and multipotent stem cells for clinical use. It offers a new experimental approach that provides a holistic measurement of macromolecular composition such that a signature representing the internal cellular phenotype is obtained. The use of this technique therefore contributes information that is complementary to that acquired by conventional genetic and immunohistochemical methods.

Cao, Julie; Ng, Elizabeth S.; McNaughton, Donald; Stanley, Edouard G.; Elefanty, Andrew G.; Tobin, Mark J.; Heraud, Philip

2013-01-01

410

Construction of protein distance matrix based on amino acid indices and Discrete Fourier Transform.  

PubMed

Protein distance matrix is widely used in various protein sequence analyses, and mainly obtained by using pairwise sequence alignment scores or protein sequence homology, which fail to take into consideration of individual physical characteristics of protein sequences and amino acids, or a combination of these features. In this paper, a new method is therefore proposed for constructing protein distance matrix based on natural amino acid indices in combination with Discrete Fourier Transform (DFT). PMID:24110625

Chrysostomou, Charalambos; Seker, Huseyin

2013-07-01

411

Cavity ring-down spectroscopy with Fourier-transform-limited light pulses  

Microsoft Academic Search

We have investigated the implications of using a pulsed, nearly Fourier-transform-limited, single-mode light source for cavity ring-down spectroscopy (CRDS) in the mid-infrared spectral range. We show that in the case where the coherence time and duration of the light pulse exceeds the cavity roundtrip time, mode beating generates oscillations in the ring-down waveform. When the period of the oscillations is

J. Martin; B. A. Paldus; P. Zalicki; E. H. Wahl; T. G. Owano; J. S. Harris; C. H. Kruger; R. N. Zare

1996-01-01

412

Orthogonal Signal Correction Used for Noise Elimination of Open Path Fourier Transform Infrared Spectra  

Microsoft Academic Search

Open path Fourier transform infrared (OP–FTIR) spectroscopy is qualified in detecting mixtures by multivariate calibration methods such as partial least squares (PLS); however, its applications are still restricted by background noise, which is unavoidable for OP–FTIR spectra and cannot be resolved solely by multivariate calibration methods. Hence OP–FTIR spectra are often pretreated before the data are subjected to the multivariate

Lin Zhang; Liming Zhang; Yan Li; Junde Wang

2005-01-01

413

Applying open-path Fourier transform infrared spectroscopy for measuring aerosols  

Microsoft Academic Search

This paper examines the feasibility of using Open-Path Fourier Transform Infrared Spectroscopy (OP-FTIR) to measure aerosols. The extinction spectra of water, ammonium nitrate, and ammonium sulfate aerosols were first simulated with various particle size distributions (geometric mean ranged from 2 to 10 ? m; geometric standard deviation ranged from 1.1 to 2.5) based on the Mie theory. An optimization procedure

Chang-Fu Wu; Yen-Ling Chen; Chih-Chieh Chen; Tzu-Ting Yang; Pao-Erh Chang

2007-01-01

414

Open-path Fourier transform infrared spectrometry characterization of low temperature combustion gases in biomass fuels  

Microsoft Academic Search

Accurate determination of gas concentration emitted during thermal degradation (pyrolysis) of biomass in forest fires is one of the keypoints in recent research on physical-based fire spread models. However, it is a very cumbersome task not well solved by classical invasive sensors and procedures. In this work, a methodology to use open-path Fourier transform-based infrared (OP-FTIR) spectrometry has been applied

A. J. de Castro; A. M. Lerma; F. López; M. Guijarro; C. Díez; C. Hernando; J. Madrigal

2007-01-01

415

Evaluation of an Open-Path Fourier Transform Infrared Spectrophotometer Using an Exposure Chamber  

Microsoft Academic Search

This study investigated the use of a controlled outdoor exposure chamber to evaluate the accuracy of an open-path Fourier transform infrared (OP-FTIR) spectrometer, using path lengths that are found in the workplace. A range of stable homogenous pollutant concentrations of toluene and cyclohexane were generated in the chamber, multiple backgrounds were taken throughout each sampling day, and open-path measurements were

L. A. Todd

1996-01-01

416

Imaging open-path Fourier transform infrared spectrometer for 3D cloud profiling  

Microsoft Academic Search

OPTRA and University of North Carolina are developing an imaging open-path Fourier transform infrared (I-OP-FTIR) spectrometer for 3D profiling of chemical and biological agent simulant plumes released into test ranges and chambers. An array of I-OP-FTIR instruments positioned around the perimeter of the test site, in concert with advanced spectroscopic algorithms, enables real time tomographic reconstruction of the plume. The

Julia Rentz Dupuis; David J. Mansur; Robert Vaillancourt; Thomas Evans; Elizabeth Schundler; Lori Todd; Kathleen Mottus

2008-01-01

417

Transmission quantification for open path Fourier transform spectroscopy with temperature compensation  

Microsoft Academic Search

This dissertation contains analyses of new methods for determining the concentration and temperature of atmospheric gases from the data generated by an open-path Fourier transform (OP-FTIR) spectrometer. The concept of FTIR and the subset OP-FTIR are explained in terms of the physical instrumentation and the traditional Beer-Lambert Law based absorbance quantification. The important problems of background collection and water vapor

Robert Stiles Crampton

2007-01-01

418

Leakage-free identification of FRF's with the discrete time Fourier transform  

Microsoft Academic Search

The discrete time Fourier transform (DTFT) has for long been used for non-parametric measurement of frequency response functions (FRF). However, beyond the appreciable simplicity and computational efficiency of the method, its use has been severely criticised when applied to stationary random signals because of the inherent spectral leakage it induces—e.g. in the so-called H1, H2, H3, Hv, etc. estimators. This

J. Antoni

2006-01-01

419

Influence of external voltage on the reprotonated polyaniline films by Fourier Transform Infrared spectroscopy  

Microsoft Academic Search

In this paper, we reported the electrical fourier transform infrared (FT-IR) spectra measurements on the reprotonated polyaniline (PANI) thin films. Application of external voltage reduced the intensity in FT-IR spectra and resulted in the shift of band situation. The FT-IR spectra as a function of temperature were also conducted in order to investigate the effect of Joule heating. We found

Tieli Zhou; Shuangxi Xing; Chuanzhou Zhang; Yan Wu; Chun Zhao

2009-01-01

420

Numerical modelling of the two-dimensional Fourier transformed Vlasov–Maxwell system  

Microsoft Academic Search

The two-dimensional Vlasov–Maxwell system, for a plasma with mobile, magnetised electrons and ions, is investigated numerically. A previously developed method for solving the two-dimensional electrostatic Vlasov equation, Fourier transformed in velocity space, for mobile electrons and with ions fixed in space, is generalised to the fully electromagnetic, two-dimensional Vlasov–Maxwell system for mobile electrons and ions. Special attention is paid to

Bengt Eliasson

2003-01-01

421

Fourier transform infrared (FTIR) spectroscopy for analysis of extra virgin olive oil adulterated with palm oil  

Microsoft Academic Search

Fourier transform infrared (FTIR) spectroscopy has been developed for analysis of extra virgin olive oil (EVOO) adulterated with palm oil (PO). Measurements were made on pure EVOO and that adulterated with varying concentrations of PO (1.0–50.0% wt.\\/wt. in EVOO). Two multivariate calibrations, namely partial least square (PLS) and principle component regression (PCR) were optimized for constructing the calibration models, either

A. Rohman; Y. B. Che Man

2010-01-01

422

Hyperfine resolved spectrum of the bromomethyl radical, CH2Br, by Fourier transform microwave spectroscopy  

Microsoft Academic Search

Pure rotational spectra of the bromomethyl radical, CH2Br, were measured by using a Fourier transform microwave (FT-MW) spectrometer in order to fully resolve hyperfine structures arising from both the bromine and hydrogen nuclei. We detected a total of 124 lines for the 79Br and 81Br isotopomers, including Ka=0 (ortho species) and Ka=1 (para species). No hyperfine splitting due to the

H. Ozeki; T. Okabayashi; M. Tanimoto; S. Saito; S. Bailleux

2007-01-01

423

Thermogravimetric coupled with Fourier transform infrared analysis study on thermal treatment of monopotassium phosphate residue  

Microsoft Academic Search

In China, safe disposal of hazardous waste is more and more a necessity, urged by rapid economic development. The pyrolysis\\u000a and combustion characteristics of a residue from producing monopotassium phosphate (monopotassium phosphate residue), considered\\u000a as a hazardous waste, were studied using a thermogravimetric, coupled with Fourier transform infrared analyzer (TG-FTIR).\\u000a Both pyrolysis and combustion runs can be subdivided into three

Yuheng Feng; Xuguang Jiang; Yong Chi; Xiaodong Li; Hongmei Zhu

2011-01-01

424

Imaging Geostationary Fourier Transform Spectrometer-revolutionary tool for tropospheric chemistry  

Microsoft Academic Search

The Geostationary Imaging Fourier Transform Spectrometer (GIFTS) has been selected by the National Aeronautics and Space Administration (NASA) for its 2004 New Millennium Program mission. The GIFTS geophysical data products are derived from measurements of atmospheric thermal emission in 2 spectral bands: 685-1130 cm-1 and 1650-2250 cm-1, at high spectral resolution (up to 0.3 cm-1) on a 4-km spatial grid.

N. S. Pougatchev; W. L. Smith; F. W. Harrison; A. M. Larar; C. P. Rinsland; D. J. Jacob; I. Bey; B. D. Field; R. M. Yantosca; A. Huang; S. R. Nolf; S. V. Kireev

2001-01-01

425

Remote measurement of gaseous pollutant concentrations using a mobile Fourier transform interferometer system  

Microsoft Academic Search

A commercial Fourier transform interferometer system with telescopic optics has been installed in a van and used to make long-path absorption and single-ended emission measurements of gaseous pollutant concentrations at a number of geographical locations. The system covers the IR spectra region from 650 cm⁻¹ to 6000 cm⁻¹ at a maximum resolution of 0.06 cm⁻¹. For many pollutants, concentrations in

William F. Herget; James D. Brasher

1979-01-01

426

Remote measurement of gaseous pollutant concentrations using a mobile Fourier transform interferometer system  

Microsoft Academic Search

A commercial Fourier-transform interferometer system with telescopic optics has been installed in a van and used to make long-path absorption and single-ended emission measurements of gaseous pollutant concentrations at a number of geographical locations. The system covers the IR spectral region from 650 to 6000 kaysers at a maximum resolution of 0.06 kayser. For many pollutants, concentrations in the 1-10-ppb

W. F. Herget; J. D. Brasher

1979-01-01

427

Fourier-transform-limited performance of a lithographically scribed planar holographic Bragg reflector  

Microsoft Academic Search

Planar holographic Bragg reflectors (HBRs) are computer-generated two-dimensional (2-D) slab-waveguide-based refractive-index gratings. HBRs provide the spectral filtering function of fiber Bragg gratings but-enabled by the 2-D slab waveguide geometry-add the capability to spatially route signals. Here, we report on a silica-on-silicon-based focusing HBR providing 17 GHz, essentially Fourier-transform-limited, spectral resolution. This result comprises the first time deep ultraviolet projection lithography

C. Greiner; D. Iazikov; T. W. Mossberg

2004-01-01

428

Fourier transform and convolution subroutines for the IBM 3090 Vector Facility  

SciTech Connect

A set of highly optimized subroutines for digital signal processing has been included in the Engineering and Scientific Subroutine Library (ESSL) for the IBM 3090 Vector Facility. These include FORTRAN-callable subroutines for Fourier transforms, convolution, and correlation. The subroutines are carefully designed and tuned for optimal vector and cache performance. Speedups of up to 9 1/2 times over scalar performance on the 3090 have been obtained.

Agarwal, R.C.; Cooley, J.W.

1986-03-01

429

Depth profile study of large-sized coal samples by Fourier transform infrared photoacoustic spectroscopy  

Microsoft Academic Search

A multidisciplinary approach is demonstrated to elucidate coal weathering at a molecular level. Fourier Transform Infrared Photoacoustic Spectroscopy (FT-IR\\/PAS) provides a technique for a compositional depth profile of coal by simply varying the modulation frequency (mirror velocity) of the light impinging upon the solid surface. In order that the potential of this technique in this field could be evaluated, large-sized

Tiziana Zerlia

1986-01-01

430

Study of coal oxidation kinetics by Fourier Transform Infrared-Photoacoustic Spectroscopy (FTIR-PAS)  

Microsoft Academic Search

Fourier Transform Infrared-Photoacoustic Spectroscopy (FTIR-PAS) was used to measure oxidation-induced changes in IR absorbance bands of coal during exposure to air in an oven for up to 200 h. Studies were conducted at oxidation temperatures of 110, 120, 130, and 140°C on raw Illinois No. 6 coal and at 140°C on coals treated with HCl or CaClâ aqueous solutions in

P. L. Chien; R. Markuszewski; H. G. Araghi; J. F. McClelland

1985-01-01

431

3D spectral imaging with synchrotron Fourier transform infrared spectro-microtomography.  

PubMed

We report Fourier transform infrared spectro-microtomography, a nondestructive three-dimensional imaging approach that reveals the distribution of distinctive chemical compositions throughout an intact biological or materials sample. The method combines mid-infrared absorption contrast with computed tomographic data acquisition and reconstruction to enhance chemical and morphological localization by determining a complete infrared spectrum for every voxel (millions of spectra determined per sample). PMID:23913258

Martin, Michael C; Dabat-Blondeau, Charlotte; Unger, Miriam; Sedlmair, Julia; Parkinson, Dilworth Y; Bechtel, Hans A; Illman, Barbara; Castro, Jonathan M; Keiluweit, Marco; Buschke, David; Ogle, Brenda; Nasse, Michael J; Hirschmugl, Carol J

2013-08-04

432

Rapid scan Fourier transform detection of a frequency encoded quartz crystal microbalance array  

NASA Astrophysics Data System (ADS)

A detection method for thickness shear mode (TSM) or quartz crystal microbalance (QCM) sensor arrays is described. Each element of the sensor array is frequency encoded so that it has a unique resonant frequency and can be identified under any operating condition. Frequency encoding of TSM sensors can be realized (1) by creating individual sensors with different thicknesses of piezoelectric base material or (2) preferably by electroplating sensors of identical piezoelectric base material thickness with predetermined thicknesses of metal films. Frequency changes can be detected by use of pulsed Fourier transform method or rapid scan Fourier transform method with a heterodyne configuration in which frequency reference is generated by a local oscillator based on a device modified according to the frequency encoding procedure. The detection method allows high analysis speed and low cost in hardware construction. A four-sensor chemical vapor detection system is designed and constructed to demonstrate the principle of frequency encoding and rapid scan Fourier transform detection for QCM arrays.

Guan, Shenheng; Nielsen, Ralph B.

2003-12-01

433

Single-channel color image encryption based on iterative fractional Fourier transform and chaos  

NASA Astrophysics Data System (ADS)

A single-channel color image encryption is proposed based on iterative fractional Fourier transform and two-coupled logistic map. Firstly, a gray scale image is constituted with three channels of the color image, and permuted by a sequence of chaotic pairs which is generated by two-coupled logistic map. Firstly, the permutation image is decomposed into three components again. Secondly, the first two components are encrypted into a single one based on iterative fractional Fourier transform. Similarly, the interim image and third component are encrypted into the final gray scale ciphertext with stationary white noise distribution, which has camouflage property to some extent. In the process of encryption and description, chaotic permutation makes the resulting image nonlinear and disorder both in spatial domain and frequency domain, and the proposed iterative fractional Fourier transform algorithm has faster convergent speed. Additionally, the encryption scheme enlarges the key space of the cryptosystem. Simulation results and security analysis verify the feasibility and effectiveness of this method.

Sui, Liansheng; Gao, Bo

2013-06-01

434

Reservoir information extraction using a fractional fourier transform and a smooth pseudo Wigner-Ville distribution  

NASA Astrophysics Data System (ADS)

Currently, it is difficult for people to express signal information simultaneously in the time and frequency domains when analyzing acoustic logging signals using a simple-time or frequency-domain method. It is difficult to use a single type of time-frequency analysis method, which affects the feasibility of acoustic logging signal analysis. In order to solve these problems, in this paper, a fractional Fourier transform and smooth pseudo Wigner-Ville distribution (SPWD) were combined and used to analyze array acoustic logging signals. The time-frequency distribution of signals with the variation of orders of fractional Fourier transform was obtained, and the characteristics of the time-frequency distribution of different reservoirs under different orders were summarized. Because of the rotational characteristics of the fractional Fourier transform, the rotation speed of the cross terms was faster than those of primary waves, shear waves, Stoneley waves, and pseudo Rayleigh waves. By choosing different orders for different reservoirs according to the actual circumstances, the cross terms were separated from the four kinds of waves. In this manner, we could extract reservoir information by studying the characteristics of partial waves. Actual logging data showed that the method outlined in this paper greatly weakened cross-term interference and enhanced the ability to identify partial wave signals.

Wang, Zhu-Wen; Wang, Xiao-Li; Xiang, Min; Liu, Jing-Hua; Zhang, Xue-Ang; Yang, Chuang

2012-12-01

435

New Potentials for Old: The Darboux Transformation in Quantum Mechanics  

ERIC Educational Resources Information Center

|The Darboux transformation in quantum mechanics is reviewed at a basic level. Examples of how this transformation leads to exactly solvable potentials related to the "particle in a box" and the harmonic oscillator are shown in detail. The connection between the Darboux transformation and some modern operator based approaches to quantum mechanics…

Williams, Brian Wesley; Celius, Tevye C.

2008-01-01

436

Transformation of Zernike coefficients: a Fourier-based method for scaled, translated, and rotated wavefront apertures.  

PubMed

This paper studies the effects on Zernike coefficients of aperture scaling, translation, and rotation, when a given aberrated wavefront is described on the Zernike polynomial basis. It proposes an analytical method for computing the matrix that enables the building of transformed Zernike coefficients from the original ones. The technique is based on the properties of Zernike polynomials and Fourier transform, and, in the case of a full aperture without central obstruction, the coefficients of the matrix are given in terms of integrals of Bessel functions. The integral formulas are exact and do not depend on any specific ordering of the polynomials. PMID:23595334

Tatulli, Eric

2013-04-01

437

Transformation of Zernike coefficients: a Fourier-based method for scaled, translated, and rotated wavefront apertures  

NASA Astrophysics Data System (ADS)

This paper studies the effects on Zernike coefficients of aperture scaling, translation and rotation, when a given aberrated wavefront is described on the Zernike polynomial basis. It proposes a new analytical method for computing the matrix that enables the building of the transformed Zernike coefficients from the original ones. The technique is based on the properties of Zernike polynomials Fourier Transform and, in the case of a full aperture without central obstruction, the coefficients of the matrix are given in terms of integrals of Bessel functions. The integral formulas are exact and do not depend on any specific ordering of the polynomials.

Tatulli, Eric

2013-04-01

438

Quantum Computers Can Search Rapidly by Using Almost Any Transformation  

Microsoft Academic Search

A quantum computer has a clear advantage over a classical computer for\\u000aexhaustive search. The quantum mechanical algorithm for exhaustive search was\\u000aoriginally derived by using subtle properties of a particular quantum\\u000amechanical operation called the Walsh-Hadamard (W-H) transform. This paper\\u000ashows that this algorithm can be implemented by replacing the W-H transform by\\u000aalmost any quantum mechanical operation. This

Lov K. Grover

1998-01-01

439

Evaluation of small-angle scattering data of charged particles using the generalized indirect Fourier transformation technique  

Microsoft Academic Search

Small-angle x-ray and neutron scattering are widely used techniques to study the structure of colloidal particles in the size range up to 100 nm. The indirect Fourier transformation technique is well established to obtain model free real space information, but the interpretation of the results is limited to cases where particle interaction can be neglected. The extended generalized indirect Fourier

G. Fritz; A. Bergmann; O. Glatter

2000-01-01

440

Universal linear Bogoliubov transformations through one-way quantum computation  

SciTech Connect

We show explicitly how to realize an arbitrary linear unitary Bogoliubov (LUBO) transformation on a multimode quantum state through homodyne-based one-way quantum computation. Any LUBO transformation can be approximated by means of a fixed, finite-sized, sufficiently squeezed Gaussian cluster state that allows for the implementation of beam splitters (in form of three-mode connection gates) and general one-mode LUBO transformations. In particular, we demonstrate that a linear four-mode cluster state is a sufficient resource for an arbitrary one-mode LUBO transformation. Arbitrary-input quantum states including non-Gaussian states could be efficiently attached to the cluster through quantum teleportation.

Ukai, Ryuji; Yoshikawa, Jun-ichi; Iwata, Noriaki; Furusawa, Akira [Department of Applied Physics and Quantum-Phase Electronics Center, School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Loock, Peter van [Optical Quantum Information Theory Group, Max Planck Institute for the Science of Light, Institute of Theoretical Physics I, Universitaet Erlangen-Nuernberg, Staudtstrasse 7/B2, D-91058 Erlangen (Germany)

2010-03-15

441

Fourier transform infrared spectroscopy study of small transition-metal carbide clusters  

NASA Astrophysics Data System (ADS)

Small molecular clusters consisting of transition metals and carbon, which are the focus of the research, are important for their potential as astrophysically significant species and for the information they may provide about the structures and bonding mechanisms of larger transition-metal carbide structures, such as metallocarbohedrenes. Additional applications exist for semiconductors and quantum dots. The dissertation research is concerned with a new investigation of the structures and infrared signatures of novel transition-metal carbide clusters using Fourier transform infrared (FTIR) spectroscopy and density functional theory (DFT). FTIR absorption spectra were obtained by trapping the vapor produced by the simultaneous evaporation of transition metal and carbon rods with Nd:YAG lasers in an Ar matrix maintained at ˜10 K in a vacuum at ˜10 -7 Torr. Comparison of the vibrational fundamentals and isotopic shifts observed in 13C-enriched vibrational spectra to the isotopic spectra predicted by DFT has enabled the identification of vibrational fundamentals of linear NiC3Ni, cyclic TiC3, and cyclic ScC3. The nu3(sigmau) asymmetric carbon stretching mode of linear NiC3Ni has been observed at 1950.8 cm-1. Although other small nickel-carbon clusters have been investigated theoretically, this is the first experimental or theoretical study of the structure and infrared signature of NiC3Ni. Two vibrational fundamentals of cyclic TiC3 (a fanlike geometry with a transannular metal-carbon bond) were observed at nu3(a 1)=624.3 and nu5(b2)=1484.2 cm-1, corresponding to symmetric metal-carbon and asymmetric carbon-carbon stretching modes, respectively. A third frequency at 573.8 cm -1 has provisionally been assigned to the nu4( b1) fundamental. Three vibrational fundamentals of cyclic ScC3 were observed including the nu5(b 2)=1478.0 cm-1 asymmetric carbon stretch, the nu 3(a1)=557.0 cm-1 symmetric metal-carbon stretch, and the nu1(a1)=1190.7 cm-1 symmetric carbon stretch. The results for TiC3 and ScC3 provide the first unambiguous evidence of the cyclic structures suggested by earlier photoelectron spectroscopy studies, significantly improve the accuracy of the nu3(a1) measurements, and identify three new vibrational fundamentals. FTIR measured isotopic spectra for all of the fundamentals are in good agreement with the predictions of DFT simulations using the B3LYP hybrid functional. Innovative sample preparation techniques have also been developed in this investigation.

Kinzer, Raymond Edward, Jr.

442

Fourier Transform Microwave Spectroscopy of Multiconformational Molecules and Van Der Waals Complexes.  

NASA Astrophysics Data System (ADS)

With the use of a Fourier transform microwave (FTM) spectrometer, structural determinations of two types of species; multiconformational molecules and van der Waals complexes, have been performed. Presented in this thesis are three sections summarizing this research effort. The first section contains a detailed explanation of the FTM instrument. In Section II, the study of three multiconformational molecules is presented as two chapters. Finally, three chapters in Section III outline the work still in progress on many van der Waals complexes. Section I was written to be a "manual" for the FTM spectrometer and to aid new additions to the group in their understanding of the instrument. An instruction guide is necessary for home-built instruments such as this one due to their unique design and application. Vital techniques and theories are discussed and machine operation is outlined. A brief explanation of general microwave spectroscopy as performed on an FTM spectrometer is also given. Section II is composed of two chapters pertaining to multiconformational molecules. In Chapter 2, a complete structural analysis of dipropyl ether is reported. The only conformer assigned had C_{rm s} symmetry. Many transitions are yet unassigned. Chapter 3 summarizes an investigation of two nitrosamines; methyl ethyl and methyl propyl nitrosamine. Only one conformer was observed for methyl ethyl nitrosamine, but two were assigned to methyl propyl nitrosamine. Nuclear hyperfine structure and internal methyl rotation complicated the spectra. The final section, Section III, contains the ongoing progress on weakly bound van der Waals complexes. The analysis of the OCS--HBr complex identified the structure as quasi-linear with large amplitude bending motions. Five separate isotopomers were assigned. Transitions originating from the HBr--DBr complex were measured and presented in Chapter 5. Although early in the analysis, the structure was determined to be bent and deuterium bonded. The final chapter of this section is meant to be a permanent record of transition frequencies whose molecular carrier is still in question. Two different groups of transitions from two different samples are listed. Further work is needed to unambiguously assign the frequencies with a carrier and quantum numbers, however the complexes (H_2 O)--(HCl)_2 and NO--H _2O are considered possible suspects.

Hight Walker, Angela Renee

1995-01-01

443

Retina as Reciprocal Spatial Fourier Transform Space Implies ``Wave-transformation'' Functions, String Theory, the Inappropriate Uncertainty Principle, and Predicts ``Quarked'' Protons.  

NASA Astrophysics Data System (ADS)

Vision, via transform space: ``Nature behaves in a reciprocal way;' also, Rect x pressure-input sense-reports as Sinc p, indicating brain interprets reciprocal ``p'' space as object space. Use Mott's and Sneddon's Wave Mechanics and Its Applications. Wave transformation functions are strings of positron, electron, proton, and neutron; uncertainty is a semantic artifact. Neutrino-string de Broglie-Schr"odinger wave-function models for electron, positron, suggest three-quark models for protons, neutrons. Variably vibrating neutrino-quills of this model, with appropriate mass-energy, can be a vertical proton string, quills leftward; thread string circumferentially, forming three interlinked circles with ``overpasses''. Diameters are 2:1:2, center circle has quills radially outward; call it a down quark, charge --1/3, charge 2/3 for outward quills, the up quarks of outer circles. String overlap summations are nodes; nodes also far left and right. Strong nuclear forces may be --px. ``Dislodging" positron with neutrino switches quark-circle configuration to 1:2:1, `downers' outside. Unstable neutron charge is 0. Atoms build. With scale factors, retinal/vision's, and quantum mechanics,' spatial Fourier transforms/inverses are equivalent.

Mc Leod, Roger David; Mc Leod, David M.

2007-10-01

444

Stellar Astrophysics With a Dispersed Fourier Transform Spectrograph. I. Instrument Description and Orbits of Single-Lined Spectroscopic Binaries.  

National Technical Information Service (NTIS)

We have designed and constructed a second-generation version of the dispersed Fourier transform spectrograph, or dFTS. This instrument combines a spectral interferometer with a dispersive spectrograph to provide highaccuracy, high-resolution optical spect...

A. R. Hajian A. T. Cenko B. B. Behr M. Murison R. S. McMillan

2009-01-01

445

EVALUATION OF A PORTABLE FOURIER TRANSFORM INFRARED GAS ANALYZER FOR MEASUREMENTS OF AIR TOXICS IN POLLUTION PREVENTION RESEARCH  

EPA Science Inventory

A portable Fourier transform infrared gas analyzer with a photoacoustic detector performed reliably during pollution prevention research at two industrial facilities. It exhibited good agreement (within approximately 6%) with other analytical instruments (dispersive infrared and ...

446

Optimal quantum learning of a unitary transformation  

SciTech Connect

We address the problem of learning an unknown unitary transformation from a finite number of examples. The problem consists in finding the learning machine that optimally emulates the examples, thus reproducing the unknown unitary with maximum fidelity. Learning a unitary is equivalent to storing it in the state of a quantum memory (the memory of the learning machine) and subsequently retrieving it. We prove that, whenever the unknown unitary is drawn from a group, the optimal strategy consists in a parallel call of the available uses followed by a 'measure-and-rotate' retrieving. Differing from the case of quantum cloning, where the incoherent 'measure-and-prepare' strategies are typically suboptimal, in the case of learning the 'measure-and-rotate' strategy is optimal even when the learning machine is asked to reproduce a single copy of the unknown unitary. We finally address the problem of the optimal inversion of an unknown unitary evolution, showing also in this case the optimality of the 'measure-and-rotate' strategies and applying our result to the optimal approximate realignment of reference frames for quantum communication.

Bisio, Alessandro; Chiribella, Giulio; D'Ariano, Giacomo Mauro; Facchini, Stefano; Perinotti, Paolo [QUIT Group, Dipartimento di Fisica 'A. Volta' and INFN Sezione di Pavia, via Bassi 6, I-27100 Pavia (Italy); Perimeter Institute for Theoretical Physics, 31 Caroline Street North, Waterloo, Ontario N2L 2Y5 (Canada); QUIT Group, Dipartimento di Fisica 'A. Volta' and INFN Sezione di Pavia, via Bassi 6, I-27100 Pavia (Italy)

2010-03-15

447

Quasi-Fourier-transform limited, scannable, high energy titanium-sapphire laser source for high resolution spectroscopy  

Microsoft Academic Search

A tunable injection seeded Ti:sapphire laser source has been developed and tested. Slave-master tandem cavity and ramp-lock-and-fire concepts have been implemented and fully controlled by a digital signal processor. A Fourier-transform-based analysis, as well as direct measurements, have demonstrated spectral linewidths in the range of 3.5-15 MHz (HWHM), with potential tunability over the entire Ti:sapphire lasing range. A quasi-Fourier-transform limited

Patrick Dupré; Terry A. Miller

2007-01-01

448

Application of Fourier transform and autocorrelation to cluster identification in the three-dimensional atom probe.  

PubMed

Because of the increasing number of collected atoms (up to millions) in the three-dimensional atom probe, derivation of chemical or structural information from the direct observation of three-dimensional images is becoming more and more difficult. New data analysis tools are thus required. Application of a discrete Fourier transform algorithm to three-dimensional atom probe datasets provides information that is not easily accessible in real space. Derivation of mean particle size from Fourier intensities or from three-dimensional autocorrelation is an example. These powerful methods can be used to detect and image nano-segregations. Using three-dimensional 'bright-field' imaging, single nano-segregations were isolated from the surrounding matrix of an iron-copper alloy. Measurement of the inner concentration within clusters is, therefore, straightforward. Theoretical aspects related to filtering in reciprocal space are developed. PMID:15566495

Vurpillot, F; De Geuser, F; Da Costa, G; Blavette, D

2004-12-01

449

Near- to far-field transformation in the aperiodic Fourier modal method.  

PubMed

This paper addresses the task of obtaining the far-field spectrum for a finite structure given the near-field calculated by the aperiodic Fourier modal method in contrast-field formulation (AFMM-CFF). The AFMM-CFF efficiently calculates the solution to Maxwell's equations for a finite structure by truncating the computational domain with perfectly matched layers (PMLs). However, this limits the far-field solution to a narrow strip between the PMLs. The Green's function for layered media is used to extend the solution over the whole super- and substrate. The approach is validated by applying it to the problem of scattering from a cylinder for which the analytical solution is available. Moreover, a numerical study is conducted on the accuracy of the approximate far-field computed with the super-cell Fourier modal method by using the AFMM-CFF with near- to far-field transformation as a reference. PMID:24085211

Rook, Ronald; Pisarenco, Maxim; Setija, Irwan D

2013-10-01

450

Secondary structure of T4 gene 33 protein. Fourier transform infrared and circular dichroic spectroscopic studies.  

PubMed

The secondary structure of bacteriophage T4 gene 33 protein (gp33) has been quantitatively examined by using Fourier transform infrared (FT-IR) and circular dichroism (CD) spectroscopy. Resolution enhancement techniques, including Fourier deconvolution and derivative spectroscopy were used to quantitate the spectral information from the amide I bands. The relative areas of these component bands indicate 21% alpha-helix, 25% beta-sheet, 34% turn, 12% random coil and 8% other undefined structures in gp33. An analysis of the CD spectrum of gp33 at the same pH and temperature revealed 19% alpha-helix, 25% beta-sheet, 13% turn and 43% random coil structures. The possible reasons for the discrepancies in estimates of the contributions to the secondary structure from turns and random coils are discussed. PMID:9184943

Shao, W; Kearns, D R; Sanders, G M

1997-04-01

451

Modular System for Performing the Discrete Fourier Transform via the Chirp-Z Transform.  

National Technical Information Service (NTIS)

The patent provides apparatus, useful for signal processing operations which involve taking a transform of an input signal, which can be implemented in modular form. The apparatus can be implemented either with a parallel output or a serial output, depend...

J. M. Speiser H. J. Whitehouse

1976-01-01

452

SAR vibrometry using the pseudo-subspace approach based on the discrete fractional Fourier transform  

NASA Astrophysics Data System (ADS)

In synthetic-aperture radar (SAR), ground-target vibrations introduce a phase modulation in the returned signals, a phenomenon often referred to as the micro-Doppler effect. Earlier work has shown that the problem of estimating common ground-target vibrations can be transformed into the problem of successively estimating chirp parameters of the returned signal in properly sized subapertures. Recently, a method based on the discrete fractional Fourier transform (DFRFT) was proposed, in conjunction with the subaperture framework, to estimate target vibrations in the absence of noise. In this paper a pseudo-subspace approach is employed to extend the applicability of the DFRFT-based vibration-estimation method to signals that are corrupted by white noise. The new algorithm first calculates the inverse discrete Fourier transform of row and column projections of the magnitude of the DFRFT spectrum of the SAR returned signal to obtain two vectors. Next, covariance matrices are estimated from the sample covariance matrices of the two vectors. A pseudo-subspace approach is then applied to the covariance matrices to yield the pseudo-spectra. The chirp rate of the signal is estimated by finding the principle frequency component in the corresponding pseudo-spectrum. Monte-Carlo simulations demonstrate that the proposed method generally offers improved mean-square-error performance in the presence of noise compared to the direct DFRFT-based method.

Wang, Qi; Santhanam, Balu; Pepin, Matthew; Atwood, Tom; Hayat, Majeed M.

2011-05-01

453

Development and Analysis of Time Variant Discrete Fourier Transform Order Tracking  

NASA Astrophysics Data System (ADS)

Several of the common order tracking methods for solving noise and vibration problems of rotating machinery are reviewed. These methods include the fast Fourier transform (FFT) and resampling based order tracking algorithms. The time variant discrete Fourier transform (TVDFT) is developed as a new and alternative order tracking method. This method contains many advantages which the current order tracking methods do not possess. The TVDFT has the advantage of being very computationally efficient as well as the ability to minimise leakage errors. The basic TVDFT method may also be extended to a more complex method through the use of an orthogonality compensation matrix which can separate closely spaced orders as well as separate the contributions of crossing orders. The basic TVDFT is a combination of the FFT and the resampling based methods, a special case of the chirp-z transform. This method can be formulated in several different manners, one of which will give results matching the resampling based methods very closely. Both analytical and experimental data are used to establish the behavioural characteristics of this new method.

Blough, J. R.

2003-11-01

454

[The meteorological satellite spectral image registration based on Fourier-Mellin transform].  

PubMed

The meteorological satellite spectral image is an effective tool for researches on meteorological science and environmental remote sensing science. Image registration is the basis for the application of the meteorological satellite spectral image data. In order to realize the registration of the satellite image and the template image, a new registration method based on the Fourier-Mellin transform is presented in this paper. Firstly, we use the global coastline vector map data to build a landmark template, which is a reference for the meteorological satellite spectral image registration. Secondly, we choose infrared sub-image of no cloud according to the cloud channel data, and extract the edges of the infrared image by Sobel operator. Finally, the affine transform model parameters between the landmark template and the satellite image are determined by the Fourier-Mellin transform, and thus the registration is realized. The proposed method is based on the curve matching in essence. It needs no feature point extraction, and can greatly simplify the process of registration. The experimental results using the infrared spectral data of the FY-2D meteorological satellite show that the method is robust and can reach a high speed and high accuracy. PMID:23705469

Wang, Liang; Liu, Rong; Zhang, Li; Duan, Fu-Qing; Lü, Ke

2013-03-01

455

Identification of early biomarkers during acetaminophen-induced hepatotoxicity by fourier transform infrared microspectroscopy.  

PubMed

Acetaminophen is a widely prescribed drug used to relieve pain and fever; however, it is a leading cause of drug-induced liver injury and a burden on public healthcare. In this study, hepatotoxicity in mice post oral dosing of acetaminophen was investigated using liver and sera samples with Fourier Transform Infrared microspectroscopy. The infrared spectra of acetaminophen treated livers in BALB/c mice show decrease in glycogen, increase in amounts of cholesteryl esters and DNA respectively. Rescue experiments using L-methionine demonstrate that depletion in glycogen and increase in DNA are abrogated with pre-treatment, but not post-treatment, with L-methionine. This indicates that changes in glycogen and DNA are more sensitive to the rapid depletion of glutathione. Importantly, analysis of sera identified lowering of glycogen and increase in DNA and chlolesteryl esters earlier than increase in alanine aminotransferase, which is routinely used to diagnose liver damage. In addition, these changes are also observed in C57BL/6 and Nos2(-/-) mice. There is no difference in the kinetics of expression of these three molecules in both strains of mice, the extent of damage is similar and corroborated with ALT and histological analysis. Quantification of cytokines in sera showed increase upon APAP treatment. Although the levels of Tnf? and Ifn? in sera are not significantly affected, Nos2(-/-) mice display lower Il6 but higher Il10 levels during this acute model of hepatotoxicity. Overall, this study reinforces the growing potential of Fourier Transform Infrared microspectroscopy as a fast, highly sensitive and label-free technique for non-invasive diagnosis of liver damage. The combination of Fourier Transform Infrared microspectroscopy and cytokine analysis is a powerful tool to identify multiple biomarkers, understand differential host responses and evaluate therapeutic regimens during liver damage and, possibly, other diseases. PMID:23029070

Gautam, Rekha; Chandrasekar, Bhagawat; Deobagkar-Lele, Mukta; Rakshit, Srabanti; Kumar B N, Vinay; Umapathy, Siva; Nandi, Dipankar

2012-09-19

456

Frequency Acquisition in a Signal with Few Sinusoids Using Effective Fourier Transform  

NASA Astrophysics Data System (ADS)

The evaluation of discrete Fourier transforms (DFT) in a real time is a common problem in various technical areas. Nowadays, research in technology offers more and more powerful tools not only for DFT evaluation, but for many signal processing algorithms as well. However, many applications still need either a faster or cheaper solution. In spite of signal processors, where multiplication is usually a one-cycl-operation, in VLSI design of signal processing algorithm, the number of multiplications is one of the important factors for the effective complexity limit of the algorithms. This paper describes a novel algorithm (Effective Fourier Transform, EFT) for an approximative computation of a DFT without multiplication. The algorithm is based on the generation of a discrete harmonic function. Considering some constraints for the frequency of the signal, an arithmetic shift can be used instead of the multiplication by cos(W). Columns of the DFT- matrix can be approximated by the reorganized samples of the harmonic generator. Considering addition and arithmetic shifts as basic operations, EFT is faster than the classical "butterfly" fast Fourier transform. An error analysis of the algorithm depends on the speed limitation. Several factors, such as the length of the DFT and number of sinusoids in an analyzed spectrum have an effect on the error analysis. Maximum error cca 2 % of the spectral magnitude is guarantied for the worst case. For well- separated sinusoids in the spectrum and for some "magic" lengths of EFT, a maximum error cca 0.1% can be achieved. For statistical evaluation of the spectrum EFT is even more suitable, as one part of the algorithm can be done only once for several EFT computations.

Rozinaj, Gregor

1996-04-01

457

Fourier-transform infrared derivative spectroscopy with an improved signal-to-noise ratio.  

PubMed

Infrared derivative spectroscopy is a useful technique for finding peaks hidden in broad spectral features. A data acquisition technique is shown that will improve the signal-to-noise ratio (SNR) of Fourier-transform infrared (FTIR) derivative spectroscopy. Typically, in a FTIR measurement one samples each point for the same time interval. The effect of using a graded time interval is studied. The simulations presented show that the SNR of first-derivative FTIR spectroscopy will improve by 15% and that the SNR of second-derivative FTIR will improve by 34%. PMID:16190454

Fetterman, M R

2005-09-01

458

Fourier-transform infrared derivative spectroscopy with an improved signal-to-noise ratio  

NASA Astrophysics Data System (ADS)

Infrared derivative spectroscopy is a useful technique for finding peaks hidden in broad spectral features. A data acquisition technique is shown that will improve the signal-to-noise ratio (SNR) of Fourier-transform infrared (FTIR) derivative spectroscopy. Typically, in a FTIR measurement one samples each point for the same time interval. The effect of using a graded time interval is studied. The simulations presented show that the SNR of first-derivative FTIR spectroscopy will improve by 15% and that the SNR of second-derivative FTIR will improve by 34%.

Fetterman, M. R.

2005-09-01

459

Computation of isotopic peak center-mass distribution by Fourier transform.  

PubMed

We derive a new efficient algorithm for the computation of the isotopic peak center-mass distribution of a molecule. With the use of Fourier transform techniques, the algorithm accurately computes the total abundance and average mass of all the isotopic species with the same number of nucleons. We evaluate the performance of the method with 10 benchmark proteins and other molecules; results are compared with BRAIN, a recently reported polynomial method. The new algorithm is comparable to BRAIN in accuracy and superior in terms of speed and memory, particularly for large molecules. An implementation of the algorithm is available for download. PMID:22873736

Fernandez-de-Cossio Diaz, Jorge; Fernandez-de-Cossio, Jorge

2012-08-08

460

High Throughput Proteomics Using Fourier Transform Ion Cyclotron Resonance Mass Spectrometry  

SciTech Connect

The advent of high throughput proteomics technology for global detection and quantitation of proteins creates new opportunities and challenges for those seeking to gain greater understanding of cellular machinery. Here, we review recent advances in high-resolution capillary liquid chromatography coupled to Fourier transform ion cyclotron resonance (FTICR) mass spectrometry along with its potential application to high throughput proteomics. These technological advances combined with quantitative stable isotope labeling methodologies provide powerful tools for expanding our understanding of biology at the system-level.

Qian, Weijun; Camp, David G.; Smith, Richard D.

2004-06-01

461

Numerical simulations of turbulent fluid flows. I - Fast Fourier transform method  

NASA Astrophysics Data System (ADS)

A brief review on turbulent flow problems is presented. The large eddy simulation technique is promising for detail numerical analyses of turbulent flows using existing computers. A computer program TURBINE has been developed, in which the Poisson equation for pressure is solved by using the fast Fourier transform technique and the tri-diagonal matrix algorithm to improve numerical accuracy and cpu time. The program was tested with use of an exactly solvable problem proposed by Taylor. Good numerical accuracy was obtained and cpu time was decreased to about 1/30 as compared with SOLA program based on a pressure iteration technique.

Sakai, K.; Sekiya, T.

1984-10-01

462

Fourier Transform Spectroscopy of 18O-Enriched Carbonyl Sulfide from 1825 to 2700 cm ?1  

Microsoft Academic Search

We have measured the Fourier transform spectrum of carbonyl sulfide from 1825 to 2700 cm?1, using a sample enriched in both18O (94.0%) and17O (1.54%). A careful calibration yields a line-position accuracy between 1.5 and 3.0 10?5cm?1. We have observed and analyzed 118 infrared bands of which 93 are measured for the first time: 55 for18O12C32S, 20 for18O12C34S, 11 for18O12C33S, 1

T. Strugariu; A. Fayt; H. Bredohl; J.-F. Blavier; I. Dubois

1998-01-01

463

Assessment of fibre orientation in reinforced concrete using Fourier image transform.  

PubMed

In this study, ribbon-shaped amorphous cast-iron fibres were used to reinforce a concrete matrix. X-ray photographs have been taken to detect fibres in situ. Their orientation has been investigated by automatic image analysis methods. However, this measurement should not be influenced by the digitization on the square frame of the analyser. For that purpose, the Fourier transform was used rather than the rose of direction method. This analysis revealed the transverse isotropic nature of the spatial arrangement of these fibres, whose axis of revolution corresponds to the concrete casting axis. Such a morphological characterization of the fibre-reinforced concrete reveals its mechanical behaviour. PMID:9767490

Redon; Chermant; Chermant; Coster

1998-09-01

464

Study of coal oxidation kinetics by Fourier Transform Infrared-Photoacoustic Spectroscopy (FTIR-PAS)  

SciTech Connect

Fourier Transform Infrared-Photoacoustic Spectroscopy (FTIR-PAS) was used to measure oxidation-induced changes in IR absorbance bands of coal during exposure to air in an oven for up to 200 h. Studies were conducted at oxidation temperatures of 110, 120, 130, and 140/sup 0/C on raw Illinois No. 6 coal and at 140/sup 0/C on coals treated with HCl or CaCl/sub 2/ aqueous solutions in order to vary the concentration of exchangeable cations present. 7 refs., 5 figs.

Chien, P.L.; Markuszewski, R.; Araghi, H.G.; McClelland, J.F.

1985-01-01

465

Fast Wavefront Reconstruction in Large Adaptive Optics Systems Using the Fourier Transform  

SciTech Connect

Wavefront Reconstruction using the Fast Fourier Transform and spatial filtering is shown to be computationally tractable and sufficiently accurate for use in large Shack Hartmann-based adaptive optics systems (up to at least 10,000 actuators). This method is significantly faster and can have lower noise propagation than traditional VMM reconstructors. The boundary problem which prevented the accurate reconstruction of phase in circular apertures using square-grid FTs is identified and solved. The methods are adapted for use on the Fried-geometry. Detailed performance analysis of mean squared error and noise propagation for FT methods is presented, using both theory and simulation.

Poyneer, L; Gravel, D T; Brase, J M

2002-01-13

466

Fourier transform infrared spectroscopy reveals a rigid ?-helical assembly for the tetrameric Streptomyces lividans K+ channel  

PubMed Central

The structure of the tetrameric K+ channel from Streptomyces lividans in a lipid bilayer environment was studied by polarized attenuated total reflection Fourier transform infrared spectroscopy. The channel displays approximately 43% ?-helical and 25% ?-sheet content. In addition, H/D exchange experiments show that only 43% of the backbone amide protons are exchangeable with solvent. On average, the ?-helices are tilted 33° normal to the membrane surface. The results are discussed in relationship to the lactose permease of Escherichia coli, a membrane transport protein.

le Coutre, Johannes; Kaback, H. Ronald; Patel, C. Kumar N.; Heginbotham, Lise; Miller, Christopher

1998-01-01

467

Attosecond nonlinear Fourier transformation spectroscopy of CO{sub 2} in extreme ultraviolet wavelength region  

SciTech Connect

The interferometric autocorrelation functions of attosecond pulse trains in the time domain were measured by detecting CO{sub 2}{sup 2+} as well as the atomic and molecular fragment ions generated via two-photon absorption of intense vacuum ultraviolet-extreme ultraviolet light by CO{sub 2}. It was demonstrated that the Fourier transformation of the interferometric autocorrelation functions of the respective fragment ions appearing in a time-of-flight mass spectrum exhibit spectroscopic information in the frequency domain corresponding to the two-photon photofragment excitation spectra of CO{sub 2} and the double ionization excitation spectrum to form CO{sub 2}{sup 2+}.

Okino, Tomoya; Yamanouchi, Kaoru [Department of Chemistry, School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Extreme Photonics Research Group, RIKEN Advanced Science Institute, 2-1 Hirosawa, Wako-shi, Saitama 351-0198 (Japan); Shimizu, Toshihiko; Ma, Ri; Nabekawa, Yasuo; Midorikawa, Katsumi [Extreme Photonics Research Group, RIKEN Advanced Science Institute, 2-1 Hirosawa, Wako-shi, Saitama 351-0198 (Japan)

2008-10-28

468

Response of multiferroic composites inferred from a fast-Fourier-transform-based numerical scheme  

NASA Astrophysics Data System (ADS)

The effective response and the local fields within periodic magneto-electric multiferroic composites are investigated by means of a numerical scheme based on fast Fourier transforms. This computational framework relies on the iterative resolution of coupled series expansions for the magnetic, electric and strain fields. By using an augmented Lagrangian formulation, a simple and robust procedure which makes use of the uncoupled Green operators for the elastic, electrostatics and magnetostatics problems is proposed. Its accuracy is assessed in the cases of laminated and fibrous two-phase composites for which analytical solutions exist.

Brenner, Renald; Bravo-Castillero, Julián

2010-11-01

469

Chemical imaging with Fourier transform coherent anti-Stokes Raman scattering microscopy.  

PubMed

We report chemical imaging using Fourier transform coherent anti-Stokes Raman scattering (FTCARS) microscopy. Adding a passively phase-stable local field to amplify the weak FTCARS signal, we also demonstrate interferometric FTCARS microscopy, permitting reduced incident power to be used for imaging. We discuss signal-to-noise considerations and the conditions necessary to effectively suppress background noise, allowing FTCARS microscopy that is limited by the shot noise of the detector. We also discuss differences between the signal-to-noise obtainable by time and frequency domain coherent anti-Stokes Raman scattering (CARS) methods. PMID:19122721

Cui, Meng; Skodack, Joshua; Ogilvie, Jennifer P

2008-11-01

470

Nonlinear stationary states of the Vlasov equation in the Fourier-transformed velocity-space  

NASA Astrophysics Data System (ADS)

We give an exact expression for the nonlinear stationary solutions of the Vlasov Poisson equation in the Fourier-transformed velocity-space in both one and three space dimensions. We show that these solutions are entire functions of the amplitude of the electrostatic potential and that they converge to the van Kampen linear continuum eigenfunctions, if this amplitude tends to zero. We establish a correspondence between the nonlinear solutions and the BGK waves over the whole complex energy-plane. The solution corresponding to a phase space electron hole is investigated in detail.

Nocera, L.

2006-03-01

471

Actin-driven cell dynamics probed by Fourier transform light scattering  

PubMed Central

We applied the newly developed Fourier transform light scattering (FTLS) to study dynamic light scattering in single live cells, at a temporal scale of seconds to hours. The nanoscale cell fluctuations were measured with and without the active actin contribution. We found experimentally that the spatio-temporal signals rendered by FTLS reveal interesting cytoskeleton dynamics in glial cells (the predominant cell type in the nervous system). The active contribution of actin cytoskeleton was obtained by modulating its dynamic properties via Cytochalasin-D, a drug that inhibits actin polymerization/depolymerization.

Ding, Huafeng; Millet, Larry J.; Gillette, Martha U.; Popescu, Gabriel

2010-01-01

472

Dioxin analysis by gas chromatography-Fourier transform ion cyclotron resonance mass spectrometry (GC-FTICRMS)  

Microsoft Academic Search

The feasibility of utilizing a gas chromatograph-tandem quadrupole-Fourier transform ion cyclotron resonance mass spectrometer\\u000a (GC-MS\\/MS-FTICRMS) to analyze chlorinated-dioxins\\/furans (CDDs\\/CDFs) and mixed halogenated dioxins\\/furans (HDDs\\/HDFs) was\\u000a investigated by operating the system in the GC-FTICRMS mode. CDDs\\/CDFs and mixed HDDs\\/HDFs could be analyzed at 50,000 to\\u000a 100,000 resolving power (RP) on the capillary gas Chromatographic time scale. Initial experiments demonstrated that 1

Vince Y. Taguchi; Robert J. Nieckarz; Ray E. Clement; Stefan Krolik; Robert Williams

2010-01-01

473

Quantitative Fourier transform infrared analysis for anisidine value and aldehydes in thermally stressed oils  

Microsoft Academic Search

A Fourier transform infrared (FTIR) transmission-based spectroscopic method was investigated for the simultaneous monitoring\\u000a of aldehyde formation and the determination of anisidine value (AV) in thermally stressed oils. Synthetic calibration standards\\u000a were prepared by adding known amounts of hexanal,t-2-hexenal andt,t-2,4-decadienal to canola oil (these compounds considered representative of aldehydic compounds formed during oxidation) plus\\u000a random amounts of other compounds representative

J. Dubois; F. R. van de Voort; J. Sedman; A. A. Ismail; H. R. Ramaswamy

1996-01-01

474

Laser desorption studies of high mass biomolecules in Fourier-transform ion cyclotron resonance mass spectrometry.  

PubMed Central

Matrix-assisted laser desorption ionization is used to obtain Fourier-transform ion cyclotron resonance mass spectra of model peptides (e.g., gramicidin S, angiotensin I, renin substrate, melittin, and bovine insulin). Matrix-assisted laser desorption ionization yields ions having appreciable kinetic energies. Two methods for trapping the high kinetic energy ions are described: (i) the ion signal for [M+H]+ ions is shown to increase with increasing trapping voltages, and (ii) collisional relaxation is used for the detection of [M+H]+ ions of bovine insulin. Images

Solouki, T; Russell, D H

1992-01-01

475

The Spontaneous Loss of Coherence Catastrophe in Fourier Transform Ion Cyclotron Resonance Mass Spectrometry  

PubMed Central

The spontaneous loss of coherence catastrophe (SLCC) is a frequently observed, yet poorly studied, space-charge related effect in Fourier-transform ion cyclotron resonance mass spectrometry (FTICR-MS). This manuscript presents an application of the filter diagonalization method (FDM) in the analysis of this phenomenon. The temporal frequency behavior reproduced by frequency shift analysis using the FDM shows the complex nature of the SLCC, which can be explained by a combination of factors occurring concurrently, governed by electrostatics and ion packet trajectories inside the ICR cell.

Aizikov, Konstantin; Mathur, Raman; O'Connor, Peter B.

2009-01-01

476

Using the fast fourier transform to accelerate the computational search for RNA conformational switches.  

PubMed

Using complex roots of unity and the Fast Fourier Transform, we design a new thermodynamics-based algorithm, FFTbor, that computes the Boltzmann probability that secondary structures differ by [Formula: see text] base pairs from an arbitrary initial structure of a given RNA sequence. The algorithm, which runs in quartic time O(n(4)) and quadratic space O(n(2)), is used to determine the correlation between kinetic folding speed and the ruggedness of the energy landscape, and to predict the location of riboswitch expression platform candidates. A web server is available at http://bioinformatics.bc.edu/clotelab/FFTbor/. PMID:23284639

Senter, Evan; Sheikh, Saad; Dotu, Ivan; Ponty, Yann; Clote, Peter

2012-12-19

477

Polarization acquisition using a commercial Fourier transform spectrometer in the MWIR  

NASA Astrophysics Data System (ADS)

A spectropolarimeter utilizing an Oriel MIR8000 Fourier Transform Spectrometer in the MWIR is demonstrated. The use of the channeled spectral technique, originally developed by K. Oka, is created with the use of two AR coated Yttrium Vanadate (YVO4) crystal retarders with a 2:1 thickness ratio. A basic mathematical model for the system is presented, showing that the Stokes parameters are directly present in the interferogram. Theoretical results are then compared with real data from the system, an improved model is provided to simulate the effects of absorption within the crystal, and error between reconstructions with phase-corrected and raw interferograms is analyzed.

Kudenov, Michael W.; Hagen, Nathan A.; Luo, Haitao; Dereniak, Eustace L.; Robertson, Shawn; Montilla, Leonardo G.; Vo, Tom B.; Tam, Justina; Nichols, Julia D.; Gerhart, Grant R.

2006-09-01

478

A zero-dispersion monochromator and two-beam output for UV Fourier transform absorption spectrometry  

NASA Astrophysics Data System (ADS)

The motivation for using a zero-dispersion monochromator as a band-pass filter with a Fourier transform spectrometer is discussed, and the design of such an instrument is presented. Benefits in performance over commercial band-pass filters are demonstrated. In addition the advantages of using the second optical output of the spectrometer are discussed, particularly with respect to absorption spectroscopy when the signal from the second output can compensate for fluctuations and drift in the intensity of the background continuum source.

Blackie, D.; Murray, J. E.; Blackwell-Whitehead, R.; Thorne, A. P.; Pickering, J. C.; Willey, B. R.

2011-06-01

479

In vivo measurement of lower back deformations with Fourier-transform profilometry  

SciTech Connect

Through the variation of their cross sections, the in vivo response of lower back muscles to low loading in an upright seated posture is explored by the Fourier-transform profilometry technique. The maximization of its sensitivity allows us to reach an adequate resolution for the evaluation of low-back displacements. Refinements of the fringe pattern analysis permit the minimization of errors. The experiments show an asymmetric distribution of the displacement during head rotation movements. Significant contribution of the lower back to grasping exertions is also observed. These results are thought to be useful for early defect detection in the lower back.

Hanafi, Abdelmalek; Gharbi, Tijani; Cornu, Jean-Yves

2005-04-20

480

Atmospheric Pressure Ionization Permanent Magnet Fourier Transform Ion Cyclotron Resonance Mass Spectrometry  

PubMed Central

A new Fourier Transform Ion Cyclotron Resonance mass spectrometer based on a permanent magnet with an atmospheric pressure ionization source was designed and constructed. A mass resolving power (full-width-at-half-maximum) of up to 80,000 in the electron ionization mode and 25,000 in the electrospray mode was obtained. Also, a mass measurement accuracy at low-ppm level has been demonstrated for peptide mixtures in a mass range of up to 1,200 m/z in the isotopically resolved mass spectra.

Vilkov, Andrey N.; Gamage, Chaminda M.; Misharin, Alexander S.; Doroshenko, Vladimir M.; Tolmachev, Dmitry A.; Tarasova, Irina A.; Kharybin, Oleg N.; Novoselov, Konstantin P.; Gorshkov, Michael V.

2007-01-01

481

Fourier-transform method for the design of wideband antireflection coatings  

NASA Astrophysics Data System (ADS)

Modified Fourier-transform techniques developed by the National Research Council of Canada are applied to the design of wideband antireflection (AR) coatings on germanium for the wavelength between 7.7 and 12.3 microns. These techniques are found to be effective even when strong constraints are imposed on the overall optical thickness and on the refractive-index range available for the film materials. Graded-index and multilayer designs are developed which had a remarkable resemblance in refractive-index structure and performance to some of the best systems found by more conventional methods.

Verly, P. G.; Dobrowolski, J. A.; Willey, R. R.

1992-07-01

482

Improve Fourier transform profilometry by locally area modulating squared binary structured pattern  

NASA Astrophysics Data System (ADS)

Our recent study found that it is very difficult to use the binary defocusing technique to completely suppress the 3rd-order harmonics, and thus it is challenging to achieve high-quality three-dimensional (3-D) measurement with the Fourier transformation method. This paper presents a novel approach to effectively eliminate the 3rd order harmonics by modulating the binary structured patterns in both x and y directions. Both simulation and experimental results will be presented to verify the performance of the proposed technique.

Lohry, William; Zhang, Song

2012-09-01

483

FOURIER TRANSFORM INFRARED VIBRATIONAL SPECTROSCOPIC IMAGING: Integrating Microscopy and Molecular Recognition *  

NASA Astrophysics Data System (ADS)

The recent development of Fourier transform infrared (FTIR) spectroscopic imaging has enhanced our capability to examine, on a microscopic scale, the spatial distribution of vibrational spectroscopic signatures of materials spanning the physical and biomedical disciplines. Recent activity in this emerging area has concentrated on instrumentation development, theoretical analyses to provide guidelines for imaging practice, novel data processing algorithms, and the introduction of the technique to new fields. To illustrate the impact and promise of this spectroscopic imaging methodology, we present fundamental principles of the technique in the context of FTIR spectroscopy and review new applications in various venues ranging from the physical chemistry of macromolecular systems to the detection of human disease.

Levin, Ira W.; Bhargava, Rohit

2005-05-01

484

Single image orthogonal fringe technique for resolution enhancement of the Fourier transform fringe analysis method  

NASA Astrophysics Data System (ADS)

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.

Tavares, Paulo J.; Vaz, Mário A. P.

2013-03-01