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1

Quantum arithmetic with the Quantum Fourier Transform  

E-print Network

The Quantum Fourier Transform offers an interesting way to perform arithmetic operations on a quantum computer. We review existing Quantum Fourier Transform adders and multipliers and propose some modifications that extend their capabilities. Among the new circuits, we propose a quantum method to compute the weighted average of a series of inputs in the transform domain.

Lidia Ruiz-Perez; Juan Carlos Garcia-Escartin

2014-11-21

2

Fourier transform multiple quantum NMR  

Microsoft Academic Search

The motivation for detecting multiple quantum transitions by a Fourier transform experiment is reviewed and an experimental approach to high resolution multiple quantum spectra in dipolar systems along with results on some protonated liquid crystal systems are described. A simple operator formalism for the essential features of the time development is presented and some applications in progress are discussed. A

G. Drobny; A. Pines; S. Sinton; D. Weitekamp; D. Wemmer

1978-01-01

3

The Fourier Transform on Quantum Euclidean Space  

NASA Astrophysics Data System (ADS)

We study Fourier theory on quantum Euclidean space. A modified version of the general definition of the Fourier transform on a quantum space is used and its inverse is constructed. The Fourier transforms can be defined by their Bochner's relations and a new type of q-Hankel transforms using the first and second q-Bessel functions. The behavior of the Fourier transforms with respect to partial derivatives and multiplication with variables is studied. The Fourier transform acts between the two representation spaces for the harmonic oscillator on quantum Euclidean space. By using this property it is possible to define a Fourier transform on the entire Hilbert space of the harmonic oscillator, which is its own inverse and satisfies the Parseval theorem.

Coulembier, Kevin

2011-05-01

4

Fourier Transforms and Quantum Computation  

Microsoft Academic Search

The foundations of computer science are built upon the modified Church-Turing thesis. This thesis states that any reasonable\\u000a model of computation can be simulated by a probabilistic Turing Machine with at most polynomial factor simulation overhead\\u000a (see [10] for a discussion). Early interest in quantum computation from a computer science perspective was sparked by results indicating\\u000a that quantum computers violate

Umesh V. Vazirani

2000-01-01

5

Purple bacteria and quantum Fourier transform  

E-print Network

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 excitons. A simplified mathematical description of the exciton states is given in Hu, X. & Schulten, K. (1997) Physics Today 50, 28-34. Using this description, we will show, by suitable labeling of the lowest energy (Qy) excited states of individual BChls, that the resulting exciton states are the quantum Fourier transform of the BChls excited states. For Rs. molischianum ring exciton states will be modeled as the four qubit quantum Fourier transform and the explicit circuit will be derived. Exciton states for Rps. acidophila ring cannot be modeled with an integer number of qubits. Both quantum Fourier transforms are instances of the hidden subgroup problem and this opens up a possibility that both purple bacteria implement an efficient quantum circuit for light harvesting.

Samir Lipovaca

2007-02-22

6

Resource requirements for a fault-tolerant quantum Fourier transform  

NASA Astrophysics Data System (ADS)

We investigate resource requirements for a fault-tolerant quantum Fourier transform. The quantum Fourier transform is a basic subroutine for quantum algorithms which provide an exponential speedup over known classical ones, such as Shor's algorithm for factoring. To implement single-qubit rotations required for a quantum Fourier transform in a fault-tolerant manner, we consider two types of approaches: gate synthesis and state distillation. While the gate synthesis approximates single-qubit rotations with basic quantum operations, the state distillation allows one to perform single-qubit rotations for a quantum Fourier transform exactly. It is unknown, however, which approach is better for a quantum Fourier transform. Here we develop a state-distillation method optimized for a quantum Fourier transform and compare this performance with those of state-of-the-art techniques for gate synthesis without and with ancillary states (ancillas). The performance is evaluated with the resource requirement for a quantum Fourier transform. The resource is measured by the total number of ? /8 gates denoted by T , which is called the T count. Contrary to the expectation, the T count for the state distillation is considerably larger than those for the ancilla-free and ancilla-assisted gate synthesis. Thus, we conclude that the ancilla-assisted gate synthesis is a better approach to a fault-tolerant quantum Fourier transform.

Goto, Hayato

2014-11-01

7

Quantum mechanical perspectives and generalization of the fractional Fourier Transformation  

E-print Network

Fourier and fractional-Fourier transformations are widely used in theoretical physics. In this paper we make quantum perspectives and generalization for the fractional Fourier transformation (FrFT). By virtue of quantum mechanical representation transformation and the method of integration within normal ordered product (IWOP) of operators, we find the key point for composing FrFT, and reveal the structure of FrFT. Following this procedure, a full family of generalized fractional transformations are discovered with the usual FrFT as one special case. The eigen-functions of arbitrary GFrT are derived explicitly.

Jun-Hua Chen; Hong-Yi Fan

2014-08-23

8

Quantum control in two-dimensional Fourier-transform spectroscopy  

SciTech Connect

We present a method that harnesses coherent control capability to two-dimensional Fourier-transform optical spectroscopy. For this, three ultrashort laser pulses are individually shaped to prepare and control the quantum interference involved in two-photon interexcited-state transitions of a V-type quantum system. In experiments performed with atomic rubidium, quantum control for the enhancement and reduction of the 5P{sub 1/2}{yields} 5P{sub 3/2} transition was successfully tested in which the engineered transitions were distinguishably extracted in the presence of dominant one-photon transitions.

Lim, Jongseok; Lee, Han-gyeol; Lee, Sangkyung; Ahn, Jaewook [Department of Physics, KAIST, Daejeon 305-701 (Korea, Republic of)

2011-07-15

9

Discrete quantum Fourier transform in coupled semiconductor double quantum dot molecules  

E-print Network

In this Letter, we present a physical scheme for implementing the discrete quantum Fourier transform in a coupled semiconductor double quantum dot system. The main controlled-R gate operation can be decomposed into many simple and feasible unitary transformations. The current scheme would be a useful step towards the realization of complex quantum algorithms in the quantum dot system.

Ping Dong; Ming Yang; Zhuo-Liang Cao

2008-11-28

10

Uncertainty Principles for the Fourier Transforms in Quantum Calculus  

E-print Network

Some properties of the $q$-Fourier-sine transform are studied and $q$-analogues of the Heisenberg uncertainty principle is derived for the $q$-Fourier-cosine transform studied in \\cite{FB} and for the $q$-Fourier-sine transform.

Neji Bettaibi; Ahmed Fitouhi; Wafa Binous

2006-02-28

11

The amplified quantum Fourier transform: solving the local period problem  

NASA Astrophysics Data System (ADS)

This paper creates and analyzes a new quantum algorithm called the Amplified Quantum Fourier Transform (QFT) for solving the following problem: The Local Period Problem: Let L = {0,1 . . . N-1} be a set of N labels and let A be a subset of M labels of period P, i.e. a subset of the form A=\\{j:j=s+rP,r=0,1ldots M-1\\} where {P? sqrt{N}} and {M ? N}, and where M is assumed known. Given an oracle f : L? {0,1} which is 1 on A and 0 elsewhere, find the local period P and the offset s.

Cornwell, David J.

2013-02-01

12

ON SOME QUANTUM MECHANICAL AND MATHEMATICAL ASPECTS OF FOURIER TRANSFORMS OF FRACTIONAL ORDERS (FTFO)  

E-print Network

ON SOME QUANTUM MECHANICAL AND MATHEMATICAL ASPECTS OF FOURIER TRANSFORMS OF FRACTIONAL ORDERS the theory and applications of Fourier transforms of fractional orders (FTFO). Quantum mechanics consid. Introduction The concept of Fourier transforms of fractional orders (FTFO) was first introduced by physicist

Soatto, Stefano

13

The Amplified Quantum Fourier Transform: solving the local period problem  

E-print Network

This paper creates and analyses a new quantum algorithm called the Amplified Quantum Fourier Transform (Amplified-QFT) for solving the following problem: The Local Period Problem: Let L = {0,1...N-1} be a set of N labels and let A be a subset of M labels of period P, i.e. a subset of the form A = {j : j = s + rP; r = 0,1...M-1} where P {0,1} which is 1 on A and 0 elsewhere, find the local period P. A separate algorithm finds the offset s. The first part of the paper defines the Amplified-QFT algorithm. The second part of the paper summarizes the main results and compares the Amplified-QFT algorithm against the Quantum Fourier Transform (QFT) and Quantum Hidden Subgroup (QHS) algorithms when solving the local period problem. It is shown that the Amplified-QFT is, on average, quadratically faster than both the QFT and QHS algorithms. The third part of the paper provides the detailed proofs of the main results, describes the method of recovering P from an observation y and describes the method for recovering the offset s.

David J. Cornwell

2012-08-12

14

A watermark strategy for quantum images based on quantum fourier transform  

NASA Astrophysics Data System (ADS)

We present a robust watermark strategy for quantum images. The watermark image is embedded into the fourier coefficients of the quantum carrier image, which will not affect the carrier image's visual effect. Before being embedded into the carrier image, the watermark image is preprocessed to be seemingly meaningless using quantum circuit, which further ensures the security of the watermark image. The properties of fourier transform ensure that the watermark embedded in the carrier image resists the unavoidable noise and cropping.

Zhang, Wei-Wei; Gao, Fei; Liu, Bin; Wen, Qiao-Yan; Chen, Hui

2013-02-01

15

Analysis and improvement of the watermark strategy for quantum images based on quantum Fourier transform  

NASA Astrophysics Data System (ADS)

We investigate the quantum watermark strategy for quantum images based on quantum Fourier transform proposed by Zhang et al.(Quantum Inf Process 12(2):793-803, 2013). It is aimed to embed the watermark image into the Fourier coefficients of the quantum carrier image without affecting the carrier image's visual effect. However, in our opinion the protocol is not clearly described and several steps are ambiguous. Moreover, we argue that the watermarking algorithm claimed by the authors is incorrect. At last, a possible improvement strategy is presented.

Yang, Yu-Guang; Jia, Xin; Xu, Peng; Tian, Ju

2013-08-01

16

Fast parallel circuits for the quantum Fourier transform  

E-print Network

We give new bounds on the circuit complexity of the quantum Fourier transform (QFT). We give an upper bound of O(log n + log log (1/epsilon)) on the circuit depth for computing an approximation of the QFT with respect to the modulus 2^n with error bounded by epsilon. Thus, even for exponentially small error, our circuits have depth O(log n). The best previous depth bound was O(n), even for approximations with constant error. Moreover, our circuits have size O(n log (n/epsilon)). We also give an upper bound of O(n (log n)^2 log log n) on the circuit size of the exact QFT modulo 2^n, for which the best previous bound was O(n^2). As an application of the above depth bound, we show that Shor's factoring algorithm may be based on quantum circuits with depth only O(log n) and polynomial-size, in combination with classical polynomial-time pre- and post-processing. In the language of computational complexity, this implies that factoring is in the complexity class ZPP^BQNC, where BQNC is the class of problems computable with bounded-error probability by quantum circuits with poly-logarithmic depth and polynomial size. Finally, we prove an Omega(log n) lower bound on the depth complexity of approximations of the QFT with constant error. This implies that the above upper bound is asymptotically optimal (for a reasonable range of values of epsilon).

Richard Cleve; John Watrous

2000-06-01

17

Fast parallel circuits for the quantum Fourier transform  

Microsoft Academic Search

We give new bounds on the circuit complexity of the quan- tum Fourier transform (QFT). We give an upper bound of on the circuit depth for comput- ing an approximation of the QFT with respect to the mod- ulus with error bounded by . Thus, even for exponen- tially small error, our circuits have depth . The best previous depth

Richard Cleve; John Watrous

2000-01-01

18

Quantum Fourier Transforms and the Complexity of Link Invariants for Quantum Doubles of Finite Groups  

NASA Astrophysics Data System (ADS)

Knot and link invariants naturally arise from any braided Hopf algebra. We consider the computational complexity of the invariants arising from an elementary family of finite-dimensional Hopf algebras: quantum doubles of finite groups [denoted {{D(G)}} , for a group G]. These induce a rich family of knot invariants and, additionally, are directly related to topological quantum computation. Regarding algorithms for these invariants, we develop quantum circuits for the quantum Fourier transform over {{D(G)}} ; in general, we show that when one can uniformly and efficiently carry out the quantum Fourier transform over the centralizers Z(g) of the elements of G, one can efficiently carry out the quantum Fourier transform over {{D(G)}} . We apply these results to the symmetric groups to yield efficient circuits for the quantum Fourier transform over {{D(S_n)}} . With such a Fourier transform, it is straightforward to obtain additive approximation algorithms for the related link invariant. As for hardness results, first we note that in contrast to those concerning the Jones polynomial—where the images of the braid group representations are dense in the unitary group—the images of the representations arising from {{D(G)}} are finite. This important difference appears to be directly reflected in the complexity of these invariants. While additively approximating "dense" invariants is {{BQP}} -complete and multiplicatively approximating them is {{#P}} -complete, we show that certain {{D(G)}} invariants (such as {{D(A_n)}} invariants) are {{BPP}} -hard to additively approximate, {{SBP}} -hard to multiplicatively approximate, and {{#P}} -hard to exactly evaluate. To show this, we prove that, for groups (such as A n ) which satisfy certain properties, the probability of success of any randomized computation can be approximated to within any {\\varepsilon} by the plat closure. Finally, we make partial progress on the question of simulating anyonic computation in groups uniformly as a function of the group size. In this direction, we provide efficient quantum circuits for the Clebsch-Gordan transform over {{D(G)}} for "fluxon" irreps, i.e., irreps of {{D(G)}} characterized by a conjugacy class of G. For general irreps, i.e., those which are associated with a conjugacy class of G and an irrep of a centralizer, we present an efficient implementation under certain conditions, such as when there is an efficient Clebsch-Gordan transform over the centralizers (this could be a hard problem for some groups). We remark that this also provides a simulation of certain anyonic models of quantum computation, even in circumstances where the group may have size exponential in the size of the circuit.

Krovi, Hari; Russell, Alexander

2015-01-01

19

Bell's measure and implementing quantum Fourier transform with orbital angular momentum of classical light  

E-print Network

We perform Bell's measurement and perform quantum Fourier transform with the classical vortex beam. The violation of Bell's inequality for such a non-separable classical correlation has been demonstrated experimentally. Based on the classical vortex beam and nonquantum entanglement between the polarization and orbital angular momentum, the Hadamard gates and conditional phase gates have been designed. Furthermore, a quantum Fourier transform has been implemented experimentally, which is the crucial final step in Shor's algorithm

Song, Xinbing; Qin, Hongwei; Li, Pengyun; Zhang, Xiangdong

2015-01-01

20

Performance scaling of Shor's algorithm with a banded quantum Fourier transform  

NASA Astrophysics Data System (ADS)

In excellent agreement with our numerical simulations of Shor's algorithm, equipped with a truncated quantum Fourier transform of bandwidth b, we find that its performance scales ˜2-?bn, where n is the number of qubits, ?b=1.1×2-2b, and the bandwidth b is the number of quantum states coupled by the quantum Fourier transform. Nonexponential behavior is observed for small n and explained analytically. The large-n exponential scaling implies that b=7 is sufficient to operate a 1000-qubit quantum computer running Shor's algorithm on the 95% performance level and implies hardware savings of the order of half a million rotation gates.

Nam, Y. S.; Blümel, R.

2012-10-01

21

Large quantum Fourier transforms are never exactly realized by braiding conformal blocks  

SciTech Connect

Fourier transform is an essential ingredient in Shor's factoring algorithm. In the standard quantum circuit model with the gate set {l_brace}U(2), controlled-NOT{r_brace}, the discrete Fourier transforms F{sub N}=({omega}{sup ij}){sub NxN}, i,j=0,1,...,N-1, {omega}=e{sup 2{pi}}{sup i} at {sup {approx}}{sup sol{approx}} at {sup N}, can be realized exactly by quantum circuits of size O(n{sup 2}), n=ln N, and so can the discrete sine or cosine transforms. In topological quantum computing, the simplest universal topological quantum computer is based on the Fibonacci (2+1)-topological quantum field theory (TQFT), where the standard quantum circuits are replaced by unitary transformations realized by braiding conformal blocks. We report here that the large Fourier transforms F{sub N} and the discrete sine or cosine transforms can never be realized exactly by braiding conformal blocks for a fixed TQFT. It follows that an approximation is unavoidable in the implementation of Fourier transforms by braiding conformal blocks.

Freedman, Michael H. [Microsoft Project Q, Kavli Institute for Theoretical Physics, University of California, Santa Barbara, California 93106-4030 (United States); Wang, Zhenghan [Microsoft Project Q, Kavli Institute for Theoretical Physics, University of California, Santa Barbara, California 93106-4030 (United States); Department of Mathematics, Indiana University, Bloomington, Indiana 47405 (United States)

2007-03-15

22

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

23

Fourier Transform Pairs The Fourier transform transforms a function of  

E-print Network

Fourier Transform Pairs The Fourier transform transforms a function of time, f(t), into a function of frequency, F(s): F {f(t)}(s) = F(s) = Z - f(t)e- j2st dt. The inverse Fourier transform transforms a func. The inverse Fourier transform of the Fourier trans- form is the identity transform: f(t) = Z - Z - f()e- j2s

Masci, Frank

24

Analyzing Signals Fourier transform  

E-print Network

Page 1 1 Analyzing Signals Fourier transform s frequency content s linear combination of sin frequency analysis s windowed Fourier transform 6 #12;Page 4 7 Gabor Transform function to analyze window Gabor Transform Spatial domain Gabor domain b #12;Page 5 9 Gabor Transform Problems s discrete version

Sweldens, Wim

25

Unraveling quantum pathways using optical 3D Fourier-transform spectroscopy  

PubMed Central

Predicting and controlling quantum mechanical phenomena require knowledge of the system Hamiltonian. A detailed understanding of the quantum pathways used to construct the Hamiltonian is essential for deterministic control and improved performance of coherent control schemes. In complex systems, parameters characterizing the pathways, especially those associated with inter-particle interactions and coupling to the environment, can only be identified experimentally. Quantitative insight can be obtained provided the quantum pathways are isolated and independently analysed. Here we demonstrate this possibility in an atomic vapour using optical three-dimensional Fourier-transform spectroscopy. By unfolding the system’s nonlinear response onto three frequency dimensions, three-dimensional spectra unambiguously reveal transition energies, relaxation rates and dipole moments of each pathway. The results demonstrate the unique capacity of this technique as a powerful tool for resolving the complex nature of quantum systems. This experiment is a critical step in the pursuit of complete experimental characterization of a system’s Hamiltonian. PMID:23340430

Li, Hebin; Bristow, Alan D.; Siemens, Mark E.; Moody, Galan; Cundiff, Steven T.

2013-01-01

26

Photocurrent Measurements on a Quantum Cascade Laser Device by Fourier Transform Infrared Microscope  

NASA Astrophysics Data System (ADS)

Intersubband photocurrent in the InAs/AlSb mid-infrared quantum cascade laser (QCL) device is measured. To characterize subband energies in a fabricated and functioning QCL laser device, Fourier-transform infrared (FTIR) microscope is used to focus the probe light on the cleaved mirror of QCL. Photocurrent associated with intersubband transitions in the active layer are observed up to room temperature and the origin of peaks is identified by numerical simulation, which demonstrates the potential as a characterization tool for QCL devices.

Enobio, Eli Christopher I.; Sato, Hiroki; Ohtani, Keita; Ohno, Yuzo; Ohno, Hideo

2012-06-01

27

Detection and measurement of electroreflectance on quantum cascade laser device using Fourier transform infrared microscope  

SciTech Connect

We demonstrate the use of a Fourier Transform Infrared microscope system to detect and measure electroreflectance (ER) from mid-infrared quantum cascade laser (QCL) device. To characterize intersubband transition (ISBT) energies in a functioning QCL device, a microscope is used to focus the probe on the QCL cleaved mirror. The measured ER spectra exhibit resonance features associated to ISBTs under applied electric field in agreement with the numerical calculations and comparable to observed photocurrent, and emission peaks. The method demonstrates the potential as a characterization tool for QCL devices.

Enobio, Eli Christopher I.; Ohtani, Keita; Ohno, Yuzo; Ohno, Hideo, E-mail: ohno@riec.tohoku.ac.jp [Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan)] [Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan)

2013-12-02

28

Exploiting high resolution Fourier transform spectroscopy to inform the development of a quantum cascade laser based explosives detection systems  

NASA Astrophysics Data System (ADS)

Fourier Transform infrared spectroscopy (FTIR) is regularly used in forensic analysis, however the application of high resolution Fourier Transform infrared spectroscopy for the detection of explosive materials and explosive precursors has not been fully explored. This project aimed to develop systematically a protocol for the analysis of explosives and precursors using Fourier Transform infrared spectroscopy and basic data analysis to enable the further development of a quantum cascade laser (QCL) based airport detection system. This paper details the development of the protocol and results of the initial analysis of compounds of interest.

Carlysle, Felicity; Nic Daeid, Niamh; Normand, Erwan; McCulloch, Michael

2012-10-01

29

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. PMID:21742802

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

2011-01-01

30

Fractional order Fourier transform and Fourier optics  

Microsoft Academic Search

The electromagnetic field transfer from a spherical emitter to a spherical receiver is expressed through a fractional order Fourier transform. Given an emitter and a receiver, the order of the fractional transform is calculated as a function of their distance and their radii of curvature. The continuity of fractional Fourier transforms with respect to their orders corresponds to the continuity

Pierre Pellat-Finet; Georges Bonnet

1994-01-01

31

Optical 2D Fourier-transform spectra of GaAs quantum wells  

NASA Astrophysics Data System (ADS)

Optical 2D Fourier-transform spectra are presented for QWs at low temperature. Many-body effects are observed in the exciton lineshapes, and suppressed for certain polarization configuration [1]. Biexcitons are completely resolved and are formed from excitons on the same localization site. The 2D spectra simultaneously reveal homogeneous and inhomogeneous linewidths for all spectra features. Also observed are pure many-body interaction features in the form of 2-quantum transitions, which are spectrally separated from the biexciton contributions [2].[4pt] [1] A. D. Bristow, D. Karaiskaj, X. Dai, R. P. Mirin, S. T. Cundiff, Phys. Rev. B 79, 161305(R) (2009). [2] D. Karaiskaj, A. D. Bristow, L. Yang, X. Dai, R. P. Mirin, S. Mukamel, S. T. Cundiff, arXiv:0906.4068v1 [cond-mat.mes-hall] (2009).

Bristow, Alan; Karaiskaj, Denis; Dai, Xingcan; Cundiff, Steven; Yang, Lijun; Mukamel, Shaul; Mirin, Richard

2009-10-01

32

Sparse generalized Fourier transforms  

Microsoft Academic Search

Block-diagonalization of sparse equivariant discretization matrices is studied. Such matrices typically arise when partial\\u000a differential equations that evolve in symmetric geometries are discretized via the finite element method or via finite differences.\\u000a \\u000a By considering sparse equivariant matrices as equivariant graphs, we identify a condition for when block-diagonalization via\\u000a a sparse variant of a generalized Fourier transform (GFT) becomes particularly simple

Krister Åhlander; Daniel Henriksson

2007-01-01

33

Rainbow Fourier Transform  

NASA Technical Reports Server (NTRS)

We present a novel technique for remote sensing of cloud droplet size distributions. Polarized reflectances in the scattering angle range between 135deg and 165deg 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.

2012-01-01

34

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

35

Fourier-transform lidar.  

PubMed

We propose a new method based on the differential absorption lidar technique for multipollutant detection. A broadband laser is sent into the atmosphere in a wavelength range in which several pollutants absorb. The backscattered light is analyzed by a Fourier-transform spectrometer with time resolution. This mode of detection provides both spatial and high spectral resolution down to 0.01 cm(-1), allowing range-resolved measurements of several pollutants simultaneously. To demonstrate the feasibility of this method, we have measured water vapor concentration by using more than 10 individual lines in the 720-nm absorption band. The potential and the limitations are discussed critically. PMID:19862277

Douard, M; Bacis, R; Rambaldi, P; Ross, A; Wolf, J P; Fabre, G; Stringat, R

1995-10-15

36

Optical transformation from chirplet to fractional Fourier transformation kernel  

E-print Network

We find a new integration transformation which can convert a chirplet function to fractional Fourier transformation kernel, this new transformation is invertible and obeys Parseval theorem. Under this transformation a new relationship between a phase space function and its Weyl-Wigner quantum correspondence operator is revealed.

Hong-yi Fan; Li-yun Hu

2009-02-11

37

Two-quantum many-body coherences in two-dimensional fourier-transform spectra of exciton resonances in semiconductor quantum wells.  

PubMed

We present experimental coherent two-dimensional Fourier-transform spectra of Wannier exciton resonances in semiconductor quantum wells generated by a pulse sequence that isolates two-quantum coherences. By measuring the real part of the signals, we determine that the spectra are dominated by two-quantum coherences due to mean-field many-body interactions, rather than bound biexcitons. Simulations performed using dynamics controlled truncation agree with the experiments. PMID:20366499

Karaiskaj, Denis; Bristow, Alan D; Yang, Lijun; Dai, Xingcan; Mirin, Richard P; Mukamel, Shaul; Cundiff, Steven T

2010-03-19

38

Imaging Fourier Transform Spectrometer  

SciTech Connect

The operating principles of an Imaging Fourier Transform Spectrometer (IFTS) are discussed. The advantages and disadvantages of such instruments with respect to alternative imaging spectrometers are discussed. The primary advantages of the IFTS are the capacity to acquire more than an order of magnitude more spectral channels than alternative systems with more than an order of magnitude greater etendue than for alternative systems. The primary disadvantage of IFTS, or FTS in general, is the sensitivity to temporal fluctuations, either random or periodic. Data from the IRIFTS (ir IFTS) prototype instrument, sensitive in the infrared, are presented having a spectral sensitivity of 0.01 absorbance units, a spectral resolution of 6 cm{sup {minus}1} over the range 0 to 7899 cm{sup {minus}1}, and a spatial resolution of 2.5 mr.

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

1993-04-14

39

Amplified Quantum Transforms  

E-print Network

In this thesis we investigate two new Amplified Quantum Transforms. In particular we create and analyze the Amplified Quantum Fourier Transform (Amplified-QFT) and the Amplified-Haar Wavelet Transform. First, we provide a brief history of quantum mechanics and quantum computing. Second, we examine the Amplified-QFT in detail and compare it against the Quantum Fourier Transform (QFT) and Quantum Hidden Subgroup (QHS) algorithms for solving the Local Period Problem. We calculate the probabilities of success of each algorithm and show the Amplified-QFT is quadratically faster than the QFT and QHS algorithms. Third, we examine the Amplified-QFT algorithm for solving The Local Period Problem with an Error Stream. Fourth, we produce an uncertainty relation for the Amplified-QFT algorithm. Fifth, we show how the Amplified-Haar Wavelet Transform can solve the Local Constant or Balanced Signal Decision Problem which is a generalization of the Deutsch-Jozsa algorithm.

David Cornwell

2014-06-01

40

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 made…

Debnath, Lokenath

2012-01-01

41

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

42

Fast Quantum Efficiency Measurement and Characterization of Different Thin Film Solar Cells by Fourier Transform Photocurrent Spectroscopy  

Microsoft Academic Search

Fourier-transform Photocurrent Spectroscopy (FTPS) was introduced four years ago [1] as a method for fast and very sensitive evaluation of the spectral dependence of the optical absorption coefficient of photoconductive thin films and recently also for the quality assessment of thin film silicon solar cells [2]. In this contribution we refer about the FTPS characterization of different thin film solar

A. Poruba; L. Hodakova; A. Purkrt; J. Holovsky; M. Vanecek

2006-01-01

43

Tunable fractional-order Fourier transformer  

SciTech Connect

A fractional two-dimensional Fourier transformer whose orders are tuned by means of optical quadrupoles is described. It is shown that in the optical scheme considered, the Fourier-transform order a element of [0,1] in one of the mutually orthogonal planes corresponds to the transform order (2-a) in another plane, i.e., to inversion and inverse Fourier transform of the order a. (laser modes and beams)

Malyutin, A A [A.M. Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2006-01-31

44

Amplified quantum transforms  

NASA Astrophysics Data System (ADS)

In this thesis we investigate two new Amplified Quantum Transforms. In particular we create and analyze the Amplified Quantum Fourier Transform (Amplified-QFT) and the Amplified-Haar Wavelet Transform. The Amplified-QFT algorithm is used to solve the Local Period Problem. We calculate the probabilities of success and compare this algorithm with the QFT and QHS algorithms. We also examine the Amplified-QFT algorithm for solving the Local Period Problem with Error Stream. We use the Amplified-Haar Wavelet Transform for solving the Local Constant or Balanced Signal Decision Problem which is a generalization of the Deutsch-Jozsa problem.

Cornwell, David J.

45

Fourier Analysis and Structure Determination: Part I: Fourier Transforms.  

ERIC Educational Resources Information Center

Provides a brief introduction with some definitions and properties of Fourier transforms. Shows relations, ways of understanding the mathematics, and applications. Notes proofs are not included but references are given. First of three part series. (MVL)

Chesick, John P.

1989-01-01

46

Fractional Hankel transform studied by charge-amplitude state representations and complex fractional Fourier transformation.  

PubMed

Starting from a complex fractional Fourier transformation [Opt. Lett. 28, 680 (2003)], it is shown that the integral kernel of a fractional Hankel transformation is equivalent to the matrix element of an appropriate operator in the charge-amplitude state representations; i.e., the fractional Hankel transformation is endowed with a definite physical meaning (definite quantum-mechanical representation transform). PMID:14649933

Fan, Hong-yi

2003-11-15

47

Fourier transform channeled spectropolarimetry in the MWIR  

E-print Network

forms of spectroscopic measurement, such as a diffraction grating spectrometer, in the MWIR. Luo, et al, "Polarization acquisition using a commercial Fourier transform spectrometer in the MWIR. Chapman et al, "Data processing pipeline for a time-sampled imaging Fourier transform spectrometer

Dereniak, Eustace L.

48

Fourier-transform holographic microscope  

SciTech Connect

We describe a holographic microscope with a spatial resolution approaching the diffraction limit. The instrument uses a tiny drop of glycerol as a lens to create the spherically diverging reference illumination necessary for Fourier-transform holography. Measurement of the point-spread function, which is obtained by imaging a knife edge in dark-field illumination, indicates a transverse resolution of 1.4 {mu}m with wavelength {lambda} = 514.5 nm. Longitudinal resolution is obtained from the holograms by the numerical equivalent of optical sectioning. We describe the method of reconstruction and demonstrate the microscope's capability with selected biological specimens. The instrument offers two unique capabilities: (1) it can collect three-dimensional information in a single pulse of light, avoiding specimen damage and bleaching; and (2) it can record three-dimensional motion pictures from a series of light pulses. The conceptual design is applicable to a broad range of wavelengths and we discuss extension to the x-ray regime.

Haddad, W.S.; Cullen, D.; Longworth, J.W.; McPherson, A.; Boyer, K.; Rhodes, C.K. (MCR Technology Corporation, P.O. Box 10084, Chicago, Illinois 60610-0084 (United States)); Solem, J.C. (Theoretical Division, Los Alamos National Laboratory, MS B210, Los Alamos, N. M. 87545 (United States))

1992-08-20

49

The Geostationary Fourier Transform Spectrometer  

NASA Technical Reports Server (NTRS)

The Geostationary Fourier Transform Spectrometer (GeoFTS) is an imaging spectrometer designed for a geostationary orbit (GEO) earth science mission to measure key atmospheric trace gases and process tracers related to climate change and human activity. GEO allows GeoFTS to continuously stare at a region of the earth for frequent sampling to capture the variability of biogenic fluxes and anthropogenic emissions from city to continental spatial scales and temporal scales from diurnal, synoptic, seasonal to interannual. The measurement strategy provides a process based understanding of the carbon cycle from contiguous maps of carbon dioxide (CO2), methane (CH4), carbon monoxide (CO), and chlorophyll fluorescence (CF) collected many times per day at high spatial resolution (2.7kmx2.7km at nadir). The CO2/CH4/CO/CF measurement suite in the near infrared spectral region provides the information needed to disentangle natural and anthropogenic contributions to atmospheric carbon concentrations and to minimize uncertainties in the flow of carbon between the atmosphere and surface. The half meter cube size GeoFTS instrument is based on a Michelson interferometer design that uses all high TRL components in a modular configuration to reduce complexity and cost. It is self-contained and as independent of the spacecraft as possible with simple spacecraft interfaces, making it ideal to be a "hosted" payload on a commercial communications satellite mission. The hosted payload approach for measuring the major carbon-containing gases in the atmosphere from the geostationary vantage point will affordably advance the scientific understating of carbon cycle processes and climate change.

Key, Richard; Sander, Stanley; Eldering, Annmarie; Blavier, Jean-Francois; Bekker, Dmitriy; Manatt, Ken; Rider, David; Wu, Yen-Hung

2012-01-01

50

The Geostationary Fourier Transform Spectrometer  

NASA Technical Reports Server (NTRS)

The Geostationary Fourier Transform Spectrometer (GeoFTS) is an imaging spectrometer designed for an earth science mission to measure key atmospheric trace gases and process tracers related to climate change and human activity. The GeoFTS instrument is a half meter cube size instrument designed to operate in geostationary orbit as a secondary "hosted" payload on a commercial geostationary satellite mission. The advantage of GEO is the ability to continuously stare at a region of the earth, enabling frequent sampling to capture the diurnal variability of biogenic fluxes and anthropogenic emissions from city to continental scales. The science goal is to obtain a process-based understanding of the carbon cycle from simultaneous high spatial resolution measurements of carbon dioxide (CO2), methane (CH4), carbon monoxide (CO), and chlorophyll fluorescence (CF) many times per day in the near infrared spectral region to capture their spatial and temporal variations on diurnal, synoptic, seasonal and interannual time scales. The GeoFTS instrument is based on a Michelson interferometer design with a number of advanced features incorporated. Two of the most important advanced features are the focal plane arrays and the optical path difference mechanism. A breadboard GeoFTS instrument has demonstrated functionality for simultaneous measurements in the visible and IR in the laboratory and subsequently in the field at the California Laboratory for Atmospheric Remote Sensing (CLARS) observatory on Mt. Wilson overlooking the Los Angeles basin. A GeoFTS engineering model instrument is being developed which will make simultaneous visible and IR measurements under space flight like environmental conditions (thermal-vacuum at 180 K). This will demonstrate critical instrument capabilities such as optical alignment stability, interferometer modulation efficiency, and high throughput FPA signal processing. This will reduce flight instrument development risk and show that the GeoFTS design is mature and flight ready.

Key, Richard; Sander, Stanley; Eldering, Annmarie; Miller, Charles; Frankenberg, Christian; Natra, Vijay; Rider, David; Blavier, Jean-Francois; Bekker, Dmitriy; Wu, Yen-Hung

2012-01-01

51

The Geostationary Fourier Transform Spectrometer  

NASA Astrophysics Data System (ADS)

The Geostationary Fourier Transform Spectrometer (GeoFTS) is an imaging spectrometer designed for a geostationary orbit (GEO) earth science mission to measure key atmospheric trace gases and process tracers related to climate change and human activity. GEO allows GeoFTS to continuously stare at a region of the earth for frequent sampling to capture the variability of biogenic fluxes and anthropogenic emissions from city to continental spatial scales and temporal scales from diurnal, synoptic, seasonal to interannual. The measurement strategy provides a process based understanding of the carbon cycle from contiguous maps of carbon dioxide (CO2), methane (CH4), carbon monoxide (CO), and chlorophyll fluorescence (CF) collected many times per day at high spatial resolution (~2.7km×2.7km at nadir). The CO2/CH4/CO/CF measurement suite in the near infrared spectral region provides the information needed to disentangle natural and anthropogenic contributions to atmospheric carbon concentrations and to minimize uncertainties in the flow of carbon between the atmosphere and surface. The half meter cube size GeoFTS instrument is based on a Michelson interferometer design that uses all high TRL components in a modular configuration to reduce complexity and cost. It is self-contained and as independent of the spacecraft as possible with simple spacecraft interfaces, making it ideal to be a "hosted" payload on a commercial communications satellite mission. The hosted payload approach for measuring the major carbon-containing gases in the atmosphere from the geostationary vantage point will affordably advance the scientific understating of carbon cycle processes and climate change.

Key, Richard; Sander, Stanley; Eldering, Annmarie; Blavier, Jean-Francois; Bekker, Dmitriy; Manatt, Kenneth; Rider, David; Wu, Yen-Hung (James)

2012-09-01

52

Two-Dimensional Clifford Windowed Fourier Transform  

NASA Astrophysics Data System (ADS)

Recently several generalizations to higher dimension of the classical Fourier transform (FT) using Clifford geometric algebra have been introduced, including the two-dimensional (2D) Clifford-Fourier transform (CFT). Based on the 2D CFT, we establish the two-dimensional Clifford windowed Fourier transform (CWFT). Using the spectral representation of the CFT, we derive several important properties such as shift, modulation, a reproducing kernel, isometry, and an orthogonality relation. Finally, we discuss examples of the CWFT and compare the CFT and CWFT.

Bahri, Mawardi; Hitzer, Eckhard M. S.; Adji, Sriwulan

53

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

54

Demystification of the geometric Fourier transforms  

NASA Astrophysics Data System (ADS)

As it will turn out in this paper, the recent hype about most of the Clifford Fourier transforms is not thoroughly worth the pain. Almost every one that has a real application is separable and these transforms can be decomposed into a sum of real valued transforms with constant multivecor factors. This fact makes their interpretation, their analysis, and their implementation almost trivial.

Bujack, Roxana; Scheuermann, Gerik; Hitzer, Eckhard

2013-10-01

55

FOURIER TRANSFORM INFRARED SPECTROMETRY OF AMBIENT AEROSOLS  

EPA Science Inventory

Fourier transform infrared (FTIR) spectrometry has been evaluated as a method for determining the concentration of selected species present in ambient aerosols collected on Teflon filters. The filters are analyzed by transmission measurements after collection of the fine fraction...

56

Topics In Chemical Instrumentation: Fourier Transformations for Chemists Part I. Introduction to the Fourier Transform.  

ERIC Educational Resources Information Center

This paper explores how Fourier Transform (FT) mimics spectral transformation, how this property can be exploited to advantage in spectroscopy, and how the FT can be used in data treatment. A table displays a number of important FT serial/spectral pairs related by Fourier Transformations. A bibliography and listing of computer software related to…

Glasser, L.

1987-01-01

57

Replica Fourier Transform: Properties and applications  

NASA Astrophysics Data System (ADS)

The Replica Fourier Transform is the generalization of the discrete Fourier Transform to quantities defined on an ultrametric tree. It finds use in conjunction of the replica method used to study thermodynamics properties of disordered systems such as spin glasses. Its definition is presented in a systematic and simple form and its use illustrated with some representative examples. In particular we give a detailed discussion of the diagonalization in the Replica Fourier Space of the Hessian matrix of the Gaussian fluctuations about the mean field saddle point of spin glass theory. The general results are finally discussed for a generic spherical spin glass model, where the Hessian can be computed analytically.

Crisanti, A.; De Dominicis, C.

2015-02-01

58

SIGNAL APPROXIMATION VIA THE GOPHER FAST FOURIER TRANSFORM  

E-print Network

SIGNAL APPROXIMATION VIA THE GOPHER FAST FOURIER TRANSFORM By I. Ben Segal and M.A. Iwen IMA-626-7370 URL: http://www.ima.umn.edu #12;Signal Approximation via the Gopher Fast Fourier Transform I. Ben the Gopher Fast Fourier Transform (GFFT), of the more recently developed sparse Fourier transform techniques

59

Optimal modal fourier-transform wavefront control.  

PubMed

Optimal modal Fourier-transform wavefront control combines the speed of Fourier-transform reconstruction (FTR) with real-time optimization of modal gains to form a fast, adaptive wavefront control scheme. Our modal basis is the real Fourier basis, which allows direct control of specific regions of the point-spread function. We formulate FTR as modal control and show how to measure custom filters. Because the Fourier basis is a tight frame, we can use it on a circular aperture for modal control even though it is not an orthonormal basis. The modal coefficients are available during reconstruction, greatly reducing computational overhead for gain optimization. Simulation results show significant improvements in performance in low-signal-to-noise-ratio situations compared with nonadaptive control. This scheme is computationally efficient enough to be implemented with off-the-shelf technology for a 2.5 kHz, 64 x 64 adaptive optics system. PMID:16134846

Poyneer, Lisa A; Véran, Jean-Pierre

2005-08-01

60

Fast Fourier Transform algorithm design and tradeoffs  

NASA Technical Reports Server (NTRS)

The Fast Fourier Transform (FFT) is a mainstay of certain numerical techniques for solving fluid dynamics problems. The Connection Machine CM-2 is the target for an investigation into the design of multidimensional Single Instruction Stream/Multiple Data (SIMD) parallel FFT algorithms for high performance. Critical algorithm design issues are discussed, necessary machine performance measurements are identified and made, and the performance of the developed FFT programs are measured. Fast Fourier Transform programs are compared to the currently best Cray-2 FFT program.

Kamin, Ray A., III; Adams, George B., III

1988-01-01

61

Unitarity of Generalized Fourier–Gauss Transforms  

Microsoft Academic Search

A generalized Fourier–Gauss transform is an operator acting in a Boson Fock space and is formulated as a continuous linear operator acting on the space of test white noise functions. It does not admit, in general, a unitary extension with respect to the norm of the Boson Fock space induced from the Gaussian measure with variance 1 but is extended

Un Cig Ji; Nobuaki Obata

2006-01-01

62

Directional Uncertainty Principle for Quaternion Fourier Transform  

E-print Network

This paper derives a new directional uncertainty principle for quaternion valued functions subject to the quaternion Fourier transformation. This can be generalized to establish directional uncertainty principles in Clifford geometric algebras with quaternion subalgebras. We demonstrate this with the example of a directional spacetime algebra function uncertainty principle related to multivector wave packets.

Eckhard Hitzer

2013-06-06

63

History of Fourier Transform Spectrometer Technology Development  

Microsoft Academic Search

The history of Fourier Transform Spectroscopy technology is closely aligned with rapid technological developments in optical manufacturing, digital signal processing, laser technology and high precision servo mechanisms. The evolution of these technologies have also influenced historical disadvantages and even advantages of this technique of spectroscopy

Henry Buijs

64

Optical flow estimation using Fourier Mellin Transform  

Microsoft Academic Search

In this paper, we propose a novel method of computing the optical flow using the Fourier Mellin Transform (FMT). Each image in a sequence is divided into a regular grid of patches and the optical flow is estimated by calculating the phase correlation of each pair of co-sited patches using the FMT. By applying the FMT in calculating the phase

Huy Tho Ho; Roland Goecke

2008-01-01

65

Ultrafast Fourier-transform parallel processor  

SciTech Connect

A new, flexible, parallel-processing architecture is developed for a high-speed, high-precision Fourier transform processor. The processor is intended for use in 2-D signal processing including spatial filtering, matched filtering and image reconstruction from projections.

Greenberg, W.L.

1980-04-01

66

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

67

Discrete Fourier transforms of nonuniformly spaced data  

NASA Technical Reports Server (NTRS)

Time series or spatial series of measurements taken with nonuniform spacings have failed to yield fully to analysis using the Discrete Fourier Transform (DFT). This is due to the fact that the formal DFT is the convolution of the transform of the signal with the transform of the nonuniform spacings. Two original methods are presented for deconvolving such transforms for signals containing significant noise. The first method solves a set of linear equations relating the observed data to values defined at uniform grid points, and then obtains the desired transform as the DFT of the uniform interpolates. The second method solves a set of linear equations relating the real and imaginary components of the formal DFT directly to those of the desired transform. The results of numerical experiments with noisy data are presented in order to demonstrate the capabilities and limitations of the methods.

Swan, P. R.

1982-01-01

68

Electro-optic imaging Fourier transform spectrometer  

NASA Technical Reports Server (NTRS)

An Electro-Optic Imaging Fourier Transform Spectrometer (EOIFTS) for Hyperspectral Imaging is described. The EOIFTS includes an input polarizer, an output polarizer, and a plurality of birefringent phase elements. The relative orientations of the polarizers and birefringent phase elements can be changed mechanically or via a controller, using ferroelectric liquid crystals, to substantially measure the spectral Fourier components of light propagating through the EIOFTS. When achromatic switches are used as an integral part of the birefringent phase elements, the EIOFTS becomes suitable for broadband applications, with over 1 micron infrared bandwidth.

Chao, Tien-Hsin (Inventor); Znod, Hanying (Inventor)

2009-01-01

69

Electro-optic Imaging Fourier Transform Spectrometer  

NASA Technical Reports Server (NTRS)

JPL is developing an innovative compact, low mass, Electro-Optic Imaging Fourier Transform Spectrometer (E-0IFTS) for hyperspectral imaging applications. The spectral region of this spectrometer will be 1 - 2.5 pm (1000 -4000 cm-') to allow high-resolution, high-speed hyperspectral imaging applications [l-51. One application will be theremote sensing of the measurement of a large number of different atmospheric gases simultaneously in the sameairmass. Due to the use of a combination of birefiingent phase retarders and multiple achromatic phase switches toachieve phase delay, this spectrometer is capable of hyperspectral measurements similar to that of the conventionalFourier transform spectrometer but without any moving parts. In this paper, the principle of operations, systemarchitecture and recent experimental progress will be presen.

Chao, Tien-Hsin

2005-01-01

70

Electro-optic Imaging Fourier Transform Spectrometer  

NASA Technical Reports Server (NTRS)

JPL is developing an innovative 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 micron (1000-4000/cm) to allow high-resolution, high-speed hyperspectral imaging applications. One application will be the remote sensing of 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

2005-01-01

71

Programs for high-speed Fourier, Mellin and Fourier-Bessel transforms  

NASA Technical Reports Server (NTRS)

Several FORTRAN program modules for performing one-dimensional and two-dimensional discrete Fourier transforms, Mellin, and Fourier-Bessel transforms are described along with programs that realize the algebra of high speed Fourier transforms on a computer. The programs can perform numerical harmonic analysis of functions, synthesize complex optical filters on a computer, and model holographic image processing methods.

Ikhabisimov, D. K.; Debabov, A. S.; Kolosov, B. I.; Usikov, D. A.

1979-01-01

72

Pulse FourierTransform Optical Spectroscopy  

Microsoft Academic Search

The optical analog of pulse Fourier-transform NMR spectroscopy is demonstrated. Doppler-free infrared spectra are obtained for a set of closely spaced 13CH3F transitions at 9.66 mum from two-pulse echo and free-induction decay transients. The effects of elastic or inelastic collisions on the decay rate are obtained for each transition, and the long-range force laws are deduced from the dependence of

Stephen B. Grossman; A. Schenzle; Richard G. Brewer

1977-01-01

73

Fourier transforms of fractional order and their optical interpretation  

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. Fractional Fourier transforms can extend the range of spatial filtering operations.

Haldun M. Ozaktas; David Mendlovic

1993-01-01

74

CAT scan and Radon/X-ray transform Relations with the Fourier transform. Dual Radon  

E-print Network

CAT scan and Radon/X-ray transform Relations with the Fourier transform. Dual Radon Radon transform of Tomographic Type #12;CAT scan and Radon/X-ray transform Relations with the Fourier transform. Dual Radon Radon one may want to ask 2 Tomography 3 CAT scan and Radon/X-ray transform 4 Relations with Fourier

75

Noise figure of amplified dispersive Fourier transformation  

SciTech Connect

Amplified dispersive Fourier transformation (ADFT) is a powerful tool for fast real-time spectroscopy as it overcomes the limitations of traditional optical spectrometers. ADFT maps the spectrum of an optical pulse into a temporal waveform using group-velocity dispersion and simultaneously amplifies it in the optical domain. It greatly simplifies spectroscopy by replacing the diffraction grating and detector array in the conventional spectrometer with a dispersive fiber and single-pixel photodetector, enabling ultrafast real-time spectroscopic measurements. Following our earlier work on the theory of ADFT, here we study the effect of noise on ADFT. We derive the noise figure of ADFT and discuss its dependence on various parameters.

Goda, Keisuke; Jalali, Bahram [Electrical Engineering Department, University of California, Los Angeles, California 90095 (United States)

2010-09-15

76

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

77

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

78

Fourier transform methods in local gravity modeling  

NASA Technical Reports Server (NTRS)

New algorithms were derived for computing terrain corrections, all components of the attraction of the topography at the topographic surface and the gradients of these attractions. These algoriithms utilize fast Fourier transforms, but, in contrast to methods currently in use, all divergences of the integrals are removed during the analysis. Sequential methods employing a smooth intermediate reference surface were developed to avoid the very large transforms necessary when making computations at high resolution over a wide area. A new method for the numerical solution of Molodensky's problem was developed to mitigate the convergence difficulties that occur at short wavelengths with methods based on a Taylor series expansion. A trial field on a level surface is continued analytically to the topographic surface, and compared with that predicted from gravity observations. The difference is used to compute a correction to the trial field and the process iterated. Special techniques are employed to speed convergence and prevent oscillations. Three different spectral methods for fitting a point-mass set to a gravity field given on a regular grid at constant elevation are described. Two of the methods differ in the way that the spectrum of the point-mass set, which extends to infinite wave number, is matched to that of the gravity field which is band-limited. The third method is essentially a space-domain technique in which Fourier methods are used to solve a set of simultaneous equations.

Harrison, J. C.; Dickinson, M.

1989-01-01

79

Compact Fourier transform spectrometer without moving parts  

NASA Astrophysics Data System (ADS)

Fourier transform spectroscopy (FTS) is a potent analytical tool for chemical and biological analysis, but is limited by system size, expense, and robustness. To make FTS technology more accessible, we present a compact, inexpensive FTS system based on a novel liquid crystal (LC) interferometer. This design is unique because the optical path difference (OPD) is controlled by voltage applied to the LC cell. The OPD is further improved by reflecting the polarized incident light through the LC several times before reaching the second polarizer and measurement. This paper presents the theoretical model and numerical simulations for the liquid crystal Fourier transform spectrometer (LCFTS), and experimental results from the prototype. Based on the experimental results, the LCFTS performs in accordance with the theoretical predictions, achieving a maximum OPD of 210?m and a resolution of 1nm at a wavelength of 630nm. The instrumental response refresh rate is just under 1 second. Absorbance measurements were conducted for single and mixed solutions of deionized water and isopropyl alcohol, demonstrating agreement with a commercial system and literature values. We also present the LCFTS transmission spectra for varying concentrations of potassium permanganate to show system sensitivity.

Huang, Chu-Yu; Estroff, B.; Wang, Wei-Chih

2012-04-01

80

Fourier Transforms for Chemists Part III. Fourier Transforms in Data Treatment.  

ERIC Educational Resources Information Center

Discusses the factors affecting the behavior of a spectral function. Lists some important properties of Fourier transform (FT) pairs that are helpful when using the FT. Notes that these properties of the mathematical formulation have identical counterparts in the physical behavior of FT systems. (TW)

Glasser, L.

1987-01-01

81

Geometric interpretations of the Discrete Fourier Transform (DFT)  

NASA Technical Reports Server (NTRS)

One, two, and three dimensional Discrete Fourier Transforms (DFT) and geometric interpretations of their periodicities are presented. These operators are examined for their relationship with the two sided, continuous Fourier transform. Discrete or continuous transforms of real functions have certain symmetry properties. The symmetries are examined for the one, two, and three dimensional cases. Extension to higher dimension is straight forward.

Campbell, C. W.

1984-01-01

82

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.

83

Fourier transform infrared spectrometric determination of Ziram.  

PubMed

A procedure has been developed for vapour-phase Fourier transform infrared determination of Ziram, a dithiocarbamate pesticide. The method is based on the evolution of CS(2), after decomposition of the dithiocarbamate with diluted H(2)SO(4) at 50 degrees C. The CS(2) evolved was swept by a carrier flow of nitrogen to a laboratory-made infrared gas cell of 39 mm pathlength and 490 mul volume. The signals were registered as a function of time. The area of peaks obtained from absorbance measurement in the wavenumber range between 1600 and 1450 cm(-1) were interpolated in a calibration line established from Ziram standards treated in the same way as samples. The method provided an absolute limit of detection of 0.055 mg, a variation coefficient of the order of 6% for an analyte mass of 50 mg, and an analysis time of 3.5 min. PMID:18968330

Cassella, A R; Garrigues, S; de Campos, R C; de la Guardia, M

2001-07-01

84

Surface Inspection using fourier transform infrared spectroscopy  

SciTech Connect

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. Detection limits under the best of conditions are in the subnanometer range (i.e., near absolute cleanliness), excellent performance is obtained in the submicrometer range, and useful performance may exist for films tens of microns thick. Identifying and quantifying contamination such as mineral oils and greases, vegetable oils, and silicone oils on aluminum foil, galvanized sheet steel, smooth aluminum tubing, and gritblasted 7075 aluminum alloy and D6AC steel are described. The ability to map in time and space the distribution of oil stains on metals is demonstrated. Techniques for quantitatively applying oils to metals, subsequently verifying the application, and nonlinear relationships between reflectance and the quantity of oil are discussed.

Powell, G.L.; Smyrl, N.R.; Williams, D.M.; Meyers, H.M. III [Martin Marietta Energy Systems, Inc., TN (United States). Oak Ridge Y-12 Plant; Barber, T.E.; Marrero-Rivera, M. [Oak Ridge Institute for Science and Education, Oak Ridge, TN (United States)

1994-08-08

85

Double image encryption based on iterative fractional Fourier transform  

Microsoft Academic Search

We present an image encryption algorithm to simultaneously encrypt two images into a single one as the amplitudes of fractional Fourier transform with different orders. From the encrypted image we can get two original images independently by fractional Fourier transforms with two different fractional orders. This algorithm can be independent of additional random phases as the encryption\\/decryption keys. Numerical results

Zhengjun Liu; Shutian Liu

2007-01-01

86

Application of Fourier Transform Infrared Spectrophotometry in Pharmaceutical Drugs Analysis  

Microsoft Academic Search

This review provides some background to infrared spectroscopy including Fourier transform infrared spectroscopy. It is not meant to be complete or exhaustive but to provide the reader with sufficient background for selected applications in pharmaceutical analysis. Fourier transform infrared spectroscopy (FTIR) is a fast and nondestructive analytical method. Associated with chemometrics, it can become a powerful tool for the pharmaceutical

Andrei A. Bunaciu; Hassan Y. Aboul-Enein; Serban Fleschin

2010-01-01

87

Heisenberg Uncertainty Principle for the q-Bessel Fourier transform  

E-print Network

Heisenberg Uncertainty Principle for the q-Bessel Fourier transform Lazhar Dhaouadi Abstract further variant of Heisen- bergs uncertainty principle. Let f be the Fourier transform of f defined by f is defined by V [g] = R x2 g(x)dx. The Heisenberg uncertainty principle can be stated as follows V [|f|2 ]V

Paris-Sud XI, Université de

88

Multiplicity of fractional Fourier transforms and their relationships  

Microsoft Academic Search

The multiplicity of the fractional Fourier transform (FRT), which is intrinsic in any fractional operator, has been claimed by several authors, but never systematically developed. The paper starts with a general FRT definition, based on eigenfunctions and eigenvalues of the ordinary Fourier transform, which allows us to generate all possible definitions. The multiplicity is due to different choices of both

Gianfranco Cariolaro; Tomaso Erseghe; Peter Kraniauskas; Nicola Laurenti

2000-01-01

89

Polar Fourier transforms of radially sampled NMR data  

Microsoft Academic Search

Radial sampling of the NMR time domain has recently been introduced to speed up data collection significantly. Here, we show that radially sampled data can be processed directly using Fourier transforms in polar coordinates. We present a comprehensive theoretical analysis of the discrete polar Fourier transform, and derive the consequences of its application to radially sampled data using linear response

Brian E. Coggins; Pei Zhou

2006-01-01

90

Geostationary Fourier Transform Spectrometer (GeoFTS)  

NASA Astrophysics Data System (ADS)

In order to confidently project the future evolution of climate and support efforts to mitigate the climate change, quantifying the emissions of CO2 and CH4 is a national and international priority. To accomplish this goal, new observational approaches are required that operate over spatial scales ranging from regional to global, and temporal scales from diurnal to decadal. Geostationary satellite observations of CO2, CH4 and correlative quantities such as CO and chlorophyll fluorescence provide a new measurement approach to deliver the quantity and quality of data needed for improved flux estimates and an improved understanding of the partitioning between biogenic and anthropogenic sources. GeoFTS is an exciting new concept that combines the game changing technology of imaging Fourier Transform Spectroscopy with the observational advantages of a geostationary orbit. The GeoFTS observations enable well-posed surface-atmospheric carbon exchange assessments as well as quantify the atmospheric signatures of anthropogenic CO2 and CH4 emissions. GeoFTS uses a single instrument to make measurements in the near-infrared spectral region at high spectral resolution. The imaging FTS measures atmospheric CO2, CH4, and CO to deliver high-resolution maps multiple times per day. A half-meter-sized cube, the instrument is designed to be a secondary "hosted" payload on a commercial GEO satellite. The instrument leverages recent NASA technology investments, uses a flight-proven interferometer and sensor chip assemblies, and requires no new technology development. NASA and other government agencies have adopted the hosted payload implementation approach because it substantially reduces the overall mission cost. Dense continuous mapping (4 km x 4 km pixels at 40 deg. latitude) is a transformational advance beyond, and complementary to, the capabilities of the NASA missions of record in low earth orbit, providing two to three orders of magnitude improvement in the number of observations over a third of the globe below 60 deg. latitude.

Sander, S. P.; Bekker, D. L.; Blavier, J. L.; Duren, R. M.; Eldering, A.; Frankenberg, C.; Key, R.; Manatt, K.; Miller, C. E.; Natraj, V.; Rider, D. M.; Wu, Y.

2012-12-01

91

Stepwise Iterative Fourier Transform: The SIFT  

NASA Technical Reports Server (NTRS)

A program, designed specifically to study the respective effects of some common data problems on results obtained through stepwise iterative Fourier transformation of synthetic data with known waveform composition, was outlined. Included in this group were the problems of gaps in the data, different time-series lengths, periodic but nonsinusoidal waveforms, and noisy (low signal-to-noise) data. Results on sinusoidal data were also compared with results obtained on narrow band noise with similar characteristics. The findings showed that the analytic procedure under study can reliably reduce data in the nature of (1) sinusoids in noise, (2) asymmetric but periodic waves in noise, and (3) sinusoids in noise with substantial gaps in the data. The program was also able to analyze narrow-band noise well, but with increased interpretational problems. The procedure was shown to be a powerful technique for analysis of periodicities, in comparison with classical spectrum analysis techniques. However, informed use of the stepwise procedure nevertheless requires some background of knowledge concerning characteristics of the biological processes under study.

Benignus, V. A.; Benignus, G.

1975-01-01

92

A discrete Fourier transform for virtual memory machines  

NASA Technical Reports Server (NTRS)

An algebraic theory of the Discrete Fourier Transform is developed in great detail. Examination of the details of the theory leads to a computationally efficient fast Fourier transform for the use on computers with virtual memory. Such an algorithm is of great use on modern desktop machines. A FORTRAN coded version of the algorithm is given for the case when the sequence of numbers to be transformed is a power of two.

Galant, David C.

1992-01-01

93

The Extended Fourier Transform for 2D Spectral Estimation  

Microsoft Academic Search

We present a linear algebraic method, named the eXtended Fourier Transform (XFT), for spectral estimation from truncated time signals. The method is a hybrid of the discrete Fourier transform (DFT) and the regularized resolvent transform (RRT) (J. Chen et al., J. Magn. Reson.147, 129–137 (2000)). Namely, it estimates the remainder of a finite DFT by RRT. The RRT estimation corresponds

Geoffrey S. Armstrong; Vladimir A. Mandelshtam

2001-01-01

94

Two-Quantum Many-Body Coherences in Two-Dimensional Fourier-Transform Spectra of Exciton Resonances in Semiconductor Quantum Wells  

E-print Network

by a pulse sequence that isolates two-quantum coherences. By measuring the real part of the signals, we. A hallmark of many-body interactions has been the appearance of a signal for negative delay in two-pulse TFWM experiment. In TFWM, the sample is excited by two pulses, E1ðt þ � and E2ðt� with wave vectors k1

Mukamel, Shaul

95

Cryogenic Scan Mechanism for Fourier Transform Spectrometer  

NASA Technical Reports Server (NTRS)

A compact and lightweight mechanism has been developed to accurately move a Fourier transform spectrometer (FTS) scan mirror (a cube corner) in a near-linear fashion with near constant speed at cryogenic temperatures. This innovation includes a slide mechanism to restrict motion to one dimension, an actuator to drive the motion, and a linear velocity transducer (LVT) to measure the speed. The cube corner mirror is double-passed in one arm of the FTS; double-passing is required to compensate for optical beam shear resulting from tilting of the moving cube corner. The slide, actuator, and LVT are off-the-shelf components that are capable of cryogenic vacuum operation. The actuator drives the slide for the required travel of 2.5 cm. The LVT measures translation speed. A proportional feedback loop compares the LVT voltage with the set voltage (speed) to derive an error signal to drive the actuator and achieve near constant speed. When the end of the scan is reached, a personal computer reverses the set voltage. The actuator and LVT have no moving parts in contact, and have magnetic properties consistent with cryogenic operation. The unlubricated slide restricts motion to linear travel, using crossed roller bearings consistent with 100-million- stroke operation. The mechanism tilts several arc seconds during transport of the FTS mirror, which would compromise optical fringe efficiency when using a flat mirror. Consequently, a cube corner mirror is used, which converts a tilt into a shear. The sheared beam strikes (at normal incidence) a flat mirror at the end of the FTS arm with the moving mechanism, thereby returning upon itself and compensating for the shear

Brasunas, John C.; Francis, John L.

2011-01-01

96

Fourier transform based scalable image quality measure.  

PubMed

We present a new image quality assessment (IQA) algorithm based on the phase and magnitude of the 2D (twodimensional) Discrete Fourier Transform (DFT). The basic idea is to compare the phase and magnitude of the reference and distorted images to compute the quality score. However, it is well known that the Human Visual Systems (HVSs) sensitivity to different frequency components is not the same. We accommodate this fact via a simple yet effective strategy of nonuniform binning of the frequency components. This process also leads to reduced space representation of the image thereby enabling the reduced-reference (RR) prospects of the proposed scheme. We employ linear regression to integrate the effects of the changes in phase and magnitude. In this way, the required weights are determined via proper training and hence more convincing and effective. Lastly, using the fact that phase usually conveys more information than magnitude, we use only the phase for RR quality assessment. This provides the crucial advantage of further reduction in the required amount of reference image information. The proposed method is therefore further scalable for RR scenarios. We report extensive experimental results using a total of 9 publicly available databases: 7 image (with a total of 3832 distorted images with diverse distortions) and 2 video databases (totally 228 distorted videos). These show that the proposed method is overall better than several of the existing fullreference (FR) algorithms and two RR algorithms. Additionally, there is a graceful degradation in prediction performance as the amount of reference image information is reduced thereby confirming its scalability prospects. To enable comparisons and future study, a Matlab implementation of the proposed algorithm is available at http://www.ntu.edu.sg/home/wslin/reduced_phase.rar. PMID:22562758

Narwaria, Manish; Lin, Weisi; McLoughlin, Ian; Emmanuel, Sabu; Chia, Liang-Tien

2012-08-01

97

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

98

TRAITEMENT D'IMAGES TRANSFORME DE FOURIER  

E-print Network

(-jx) #1; 2 #12; TRANSFORM�E DE FOURIER CONVOLUTION 1D -FONCTIONS CONTINUES- (f # g)(x) = Z +# -# f(t)g SPECTRE . Signal sinusoïdal de fréquence f0 # f(x) = c cos(2#f0x) (c est l'amplitude du signal et T = 1/f0 FOURIER (4) Série de Fourier de l'onde carrée 1D f(x) = A0 2 + # X n=1 An cos(2#nf0x) + # X n=1 Bn sin(2

Mignotte, Max

99

A Reconfigurable Butterfly Architecture for Fourier and Fermat Transforms  

E-print Network

A Reconfigurable Butterfly Architecture for Fourier and Fermat Transforms Ali Al Ghouwayel, Yves) used for the classical operations in the complex field. The second one is the Fermat Number Transform equal to Ft, where Ft = 22t + 1 is the Fermat number, the NTT is called the Fermat Number Transform (FNT

Boyer, Edmond

100

THE UNCERTAINTY PRINCIPLE FOR FOURIER TRANSFORMS ON THE REAL LINE  

E-print Network

THE UNCERTAINTY PRINCIPLE FOR FOURIER TRANSFORMS ON THE REAL LINE MITCH HILL Abstract. This paper inversion theorem and use this to prove the classical uncertainty principle which shows that the spread. Fourier Inversion 8 5. The Uncertainty Principle 13 6. The Amrein-Berthier Theorem 15 Acknowledgments 17

May, J. Peter

101

Estimates for the Fourier-Bessel transforms of multivariate functions  

NASA Astrophysics Data System (ADS)

Two estimates useful in applications are proved for the Fourier-Bessel (or Hankel) transform in the space {L}_2 ( {{R}_ + ^2 } ) for some classes of two-variable functions characterized by a generalized modulus of continuity.

Abilov, V. A.; Kerimov, M. K.

2012-06-01

102

Surface Fourier-transform lens using a metasurface  

NASA Astrophysics Data System (ADS)

We propose a surface (or 2D) Fourier-transform lens using a gradient refractive index (GRIN) metasurface in the microwave band, which is composed of sub-wavelength quasi-periodical metallic patches on a grounded dielectric substrate. Such a metasurface supports the transverse magnetic (TM) modes of surface waves. To gradually change the size of textures, we obtain different surface refractive indices, which can be tailored to fit the required refractive-index profile of a surface Fourier-transform lens. According to the theory of spatial Fourier transformation, we make use of the proposed lens to realize surface plane-wave scanning under different feeding locations. The simulation and experimental results jointly confirm the validity of the surface Fourier-transform lens. The proposed method can also be extended to the terahertz frequency.

Li, Yun Bo; Cai, Ben Geng; Cheng, Qiang; Cui, Tie Jun

2015-01-01

103

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

104

Fourier transform techniques for the inference of cloud motion  

NASA Technical Reports Server (NTRS)

The development and evaluation are reported of phase shift techniques based on the Fourier transform for the estimation of cloud motion from geosynchronous meteorological satellite photographs. An alternative approach to cloud motion estimation, involving thresholding, was proposed and studied.

Lo, R. C.; Rosenfeld, A.

1974-01-01

105

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

106

A unified framework for the fractional Fourier transform  

Microsoft Academic Search

The paper investigates the possibility for giving a general definition of the fractional Fourier transform (FRT) for all signal classes [one-dimensional (1-D) and multidimensional, continuous and discrete, periodic and aperiodic]. Since the definition is based on the eigenfunctions of the ordinary Fourier transform (FT), the preliminary conditions is that the signal domain\\/periodicity be the same as the FT domain\\/periodicity. Within

Gianfranco Cariolaro; Tomaso Erseghe; Peter Kraniauskas; Nicola Laurenti

1998-01-01

107

The Quantum Mellin transform  

E-print Network

We uncover a new type of unitary operation for quantum mechanics on the half-line which yields a transformation to ``Hyperbolic phase space''. We show that this new unitary change of basis from the position x on the half line to the Hyperbolic momentum $p_\\eta$, transforms the wavefunction via a Mellin transform on to the critial line $s=1/2-ip_\\eta$. We utilise this new transform to find quantum wavefunctions whose Hyperbolic momentum representation approximate a class of higher transcendental functions, and in particular, approximate the Riemann Zeta function. We finally give possible physical realisations to perform an indirect measurement of the Hyperbolic momentum of a quantum system on the half-line.

J. Twamley; G. J. Milburn

2007-02-12

108

Dynamic measurement of deformation using Fourier transform digital holographic interferometry  

NASA Astrophysics Data System (ADS)

Digital holographic interferometry (DHI) is a well-established optical technique for measurement of nano-scale deformations. It has become more and more important due to the rapid development of applications in aerospace engineering and biomedicine. Traditionally, phase shift technique is used to quantitatively measure the deformations in DHI. However, it cannot be applied in dynamic measurement. Fourier transform phase extraction method, which can determine the phase distribution from only a single hologram, becomes a promising method to extract transient phases in DHI. This paper introduces a digital holographic interferometric system based on 2D Fourier transform phase extraction method, with which deformations of objects can be measured quickly. In the optical setup, the object beam strikes a CCD via a lens and aperture, and the reference beam is projected on the CCD through a single-mode fiber. A small inclination angle between the diverging reference beam and optical axial is introduced in order to physically separate the Fourier components in frequency domain. Phase maps are then obtained by the utilization of Fourier transform and windowed inverse Fourier transform. The capability of the Fourier transform DHI is discussed by theoretical discussion as well as experiments.

Gao, Xinya; Wu, Sijin; Yang, Lianxiang

2013-10-01

109

The Abel, Fourier and radon transforms on symmetric spaces  

Microsoft Academic Search

In this paper we prove a new inversion theorem and a refinement of an old\\u000asupport theorem for two Radon transforms on a symmetric space. Included are\\u000asome new identities for the Abel transform and some results about the Fourier\\u000atransform from a joint work with Rawat, Sengupta and Sitaram.

Sigurdur Helgason

2005-01-01

110

Deriving the integral representation of a fractional Hankel transform from a fractional Fourier transform.  

PubMed

We derive the integral representation of a fractional Hankel transform (FRHT) from a fractional Fourier transform. Some basic properties of the FRHT such as Parseval's theorem and its optical implementation are discussed qualitatively. PMID:18087459

Yu, L; Lu, Y; Zeng, X; Huang, M; Chen, M; Huang, W; Zhu, Z

1998-08-01

111

Electro-Optical Imaging Fourier-Transform Spectrometer  

NASA Technical Reports Server (NTRS)

An electro-optical (E-O) imaging Fourier-transform spectrometer (IFTS), now under development, is a prototype of improved imaging spectrometers to be used for hyperspectral imaging, especially in the infrared spectral region. Unlike both imaging and non-imaging traditional Fourier-transform spectrometers, the E-O IFTS does not contain any moving parts. Elimination of the moving parts and the associated actuator mechanisms and supporting structures would increase reliability while enabling reductions in size and mass, relative to traditional Fourier-transform spectrometers that offer equivalent capabilities. Elimination of moving parts would also eliminate the vibrations caused by the motions of those parts. Figure 1 schematically depicts a traditional Fourier-transform spectrometer, wherein a critical time delay is varied by translating one the mirrors of a Michelson interferometer. The time-dependent optical output is a periodic representation of the input spectrum. Data characterizing the input spectrum are generated through fast-Fourier-transform (FFT) post-processing of the output in conjunction with the varying time delay.

Chao, Tien-Hsin; Zhou, Hanying

2006-01-01

112

Linear Response Theory 15.0.6 Fourier Transform  

E-print Network

Chapter 15 Linear Response Theory 15.0.6 Fourier Transform A function of time f(t) which transform of f(t). Note that if f(t) = (t) such that (t)dt = 1, then F() = 1 2 , and (t) = 1 2 - eit d 85 #12;86 CHAPTER 15. LINEAR RESPONSE THEORY 15.0.7 Convolution Consider f(t) with transform F() and h

Palffy-Muhoray, Peter

113

Uniqueness results for the phase retrieval problem of fractional Fourier transforms of variable order  

E-print Network

In this paper, we investigate the uniqueness of the phase retrieval problem for the fractional Fourier transform (FrFT) of variable order. This problem occurs naturally in optics and quantum physics. More precisely, we show that if $u$ and $v$ are such that fractional Fourier transforms of order $\\alpha$ have same modulus $|F_\\alpha u|=|F_\\alpha v|$ for some set $\\tau$ of $\\alpha$'s, then $v$ is equal to $u$ up to a constant phase factor. The set $\\tau$ depends on some extra assumptions either on $u$ or on both $u$ and $v$. Cases considered here are $u$, $v$ of compact support, pulse trains, Hermite functions or linear combinations of translates and dilates of Gaussians. In this last case, the set $\\tau$ may even be reduced to a single point (i.e. one fractional Fourier transform may suffice for uniqueness in the problem).

Philippe Jaming

2010-09-17

114

Computing the Fast Fourier Transform on a vector computer  

NASA Technical Reports Server (NTRS)

Two algorithms are presented for performing a Fast Fourier Transform on a vector computer and are compared on the Control Data Corporation STAR-100. The relative merits of the two algorithms are shown to depend upon whether only a few or many independent transforms are desired. A theorem is proved which shows that a set of independent transforms can be computed by performing a partial transformation on a single vector. The results of this theorem also apply to nonvector machines and have reduced the average time per transform by a factor of two on the CDC 6600 computer.

Korn, D. G.; Lambiotte, J. J., Jr.

1979-01-01

115

Blind digital watermarking method in the fractional Fourier transform domain  

NASA Astrophysics Data System (ADS)

In this paper, we proposed a novel blind digital image watermarking algorithm based on the fractional Fourier transform (FRFT), which is a generalization of the ordinary Fourier transform and its output has the mixed time and frequency components of the signal. The original image is segmented into non-overlapping blocks for watermarking, and each block is transformed by the two dimensional fractional Fourier transform with two fractional orders. Then each pixel value of binary watermark is embedded by modifying the back-diagonal FRFT coefficients of each image block at the same location with a random array. After perform an inverse two dimensional fractional Fourier transform, we can obtain the watermarked image and the transform orders can be consider as the encryption keys in this method. A series of attacking experiments are performed on the proposed method. The experiments results show that the proposed algorithm not only is of good imperceptibility and security and is very robust to JPEG compression noise attacks and image manipulation operations, but also can provide protection even under compound attacks.

Lang, Jun; Zhang, Zheng-guang

2014-02-01

116

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

117

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

118

Theoretical for astigmatism Fourier transform-based imaging processor  

NASA Astrophysics Data System (ADS)

We propose a new step imaging method based on astigmatism Fourier transform for synthetic-aperture ladar imaging processor, which is mainly used in optical imaging processing system of synthetic-aperture imaging ladar. The time-domain data is translated into spatial coordinate expression suitable for space optical conversion. The Fourier transform is realized by astigmatism principle. It can simultaneously achieve radar goals focusing both on distance and azimuth. Processor scale is effectively reduced. The process of target echo confocal imaging data is simplified. The requirements of ladar imaging processing system are reduced. It has a great advantage in the synthetic-aperture imaging ladar target echo confocal imaging data processing.

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

2014-09-01

119

Fourier-transform and global contrast interferometer alignment methods  

DOEpatents

Interferometric methods are presented to facilitate alignment of image-plane components within an interferometer and for the magnified viewing of interferometer masks in situ. Fourier-transforms are performed on intensity patterns that are detected with the interferometer and are used to calculate pseudo-images of the electric field in the image plane of the test optic where the critical alignment of various components is being performed. Fine alignment is aided by the introduction and optimization of a global contrast parameter that is easily calculated from the Fourier-transform.

Goldberg, Kenneth A. (Berkeley, CA)

2001-01-01

120

Modulated Fourier Transform Raman Fiber-Optic Spectroscopy  

NASA Technical Reports Server (NTRS)

A modification to a commercial Fourier Transform (FT) Raman spectrometer is presented for the elimination of thermal backgrounds in the FT Raman spectra. The modification involves the use of a mechanical optical chopper to modulate the continuous wave laser, remote collection of the signal via fiber optics, and connection of a dual-phase digital-signal-processor (DSP) lock-in amplifier between the detector and the spectrometer's collection electronics to demodulate and filter the optical signals. The resulting Modulated Fourier Transform Raman Fiber-Optic Spectrometer is capable of completely eliminating thermal backgrounds at temperatures exceeding 300 C.

Jensen, Brian J. (Inventor); Cooper, John B. (Inventor); Wise, Kent L. (Inventor)

2000-01-01

121

Cauchy transforms of measures viewed as some functionals of Fourier transforms #  

E-print Network

Cauchy transforms of measures viewed as some functionals of Fourier transforms # Zbigniew J. Jurek Urbanik ABSTRACT. The Cauchy transform of a positive measure plays an impor­ tant role in complex analysis and more recently in so­called free probability. We show here that the Cauchy transform restricted

Jurek, Zbigniew J.

122

Cauchy transforms of measures viewed as some functionals of Fourier transforms  

E-print Network

Cauchy transforms of measures viewed as some functionals of Fourier transforms Zbigniew J. Jurek Urbanik ABSTRACT. The Cauchy transform of a positive measure plays an impor- tant role in complex analysis and more recently in so-called free probability. We show here that the Cauchy transform restricted

Jurek, Zbigniew J.

123

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

124

Achieving Efficient Polynomial Multiplication in Fermat Fields Using the Fast Fourier Transform  

E-print Network

Achieving Efficient Polynomial Multiplication in Fermat Fields Using the Fast Fourier Transform. Keywords Finite fields, polynomial multiplication, Fast Fourier Trans- form (FFT), Fermat numbers, Fermat

125

A Unified Method of Finding Laplace Transforms, Fourier Transforms, and Fourier Series. [and] An Inversion Method for Laplace Transforms, Fourier Transforms, and Fourier Series. Integral Transforms and Series Expansions. Modules and Monographs in Undergraduate Mathematics and Its Applications Project. UMAP Units 324 and 325.  

ERIC Educational Resources Information Center

This document contains two units that examine integral transforms and series expansions. In the first module, the user is expected to learn how to use the unified method presented to obtain Laplace transforms, Fourier transforms, complex Fourier series, real Fourier series, and half-range sine series for given piecewise continuous functions. In…

Grimm, C. A.

126

Discrete Fourier Transform Analysis in a Complex Vector Space  

NASA Technical Reports Server (NTRS)

Alternative computational strategies for the Discrete Fourier Transform (DFT) have been developed using analysis of geometric manifolds. This approach provides a general framework for performing DFT calculations, and suggests a more efficient implementation of the DFT for applications using iterative transform methods, particularly phase retrieval. The DFT can thus be implemented using fewer operations when compared to the usual DFT counterpart. The software decreases the run time of the DFT in certain applications such as phase retrieval that iteratively call the DFT function. The algorithm exploits a special computational approach based on analysis of the DFT as a transformation in a complex vector space. As such, this approach has the potential to realize a DFT computation that approaches N operations versus Nlog(N) operations for the equivalent Fast Fourier Transform (FFT) calculation.

Dean, Bruce H.

2009-01-01

127

Visible-NIR imaging optics for a Fourier transform spectrometer  

NASA Astrophysics Data System (ADS)

We present details of optical design, opto-mechanical design and testing of a visible-NIR imaging optical system for a Fourier transform spectrometer dedicated to astronomical application at the Mont Mégantic Observatory (Observatoire du Mont Mégantic, OMM, located south Québec city, Canada). Design considerations as well as testing and experimental results are presented.

Thibault, Simon; Reecht, Jérôme; Lavigne, Jean-François; Desnoyers, Nichola

2004-10-01

128

Fourier transform spectroscopy of cotton and cotton trash  

Technology Transfer Automated Retrieval System (TEKTRAN)

Fourier Transform techniques have been shown to have higher signal-to-noise capabilities, higher throughput, negligible stray light, continuous spectra, and higher resolution. In addition, FT spectroscopy affords for frequencies in spectra to be measured all at once and more precise wavelength calib...

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

Identification of species of Brucella using Fourier transform infrared spectroscopy  

Microsoft Academic Search

Fourier transform infrared spectroscopy (FTIR) is a technique that has been used over the years in chemical analysis for the identification of substances and is one that may be applied to the characterisation of microorganisms. The marked tendency of Brucella towards variation in the smooth rough phase, together with the laboriousness and risk involved in the methods used in their

M. A. Miguel Gómez; M. A. Bratos Pérez; F. J. Mart??n Gil; A. Dueñas D??ez; J. F. Mart??n Rodr??guez; P. Gutiérrez Rodr??guez; A. Orduña Domingo; A. Rodr??guez Torres

2003-01-01

131

Rainbow Fourier transform Mikhail D. Alexandrov a,b,n  

E-print Network

Rainbow Fourier transform Mikhail D. Alexandrov a,b,n , Brian Cairns b , Michael I. Mishchenko b Rainbow Optical particle characterization Remote sensing a b s t r a c t We present a novel technique between 1351 and 1651 exhibit a sharply defined rainbow structure, the shape of which is determined mostly

132

Rainbow Fourier transform Mikhail D. Alexandrov a,b,n  

E-print Network

71 73 75 77 79 81 Rainbow Fourier transform Mikhail D. Alexandrov a,b,n , Brian Cairns b , Michael I, USAQ3 a r t i c l e i n f o Keywords: ElectromagneticQ4 scattering Polarization Mie theory Rainbow angle range between 1351 and 1651 exhibit a sharply defined rainbow structure, the shape of which

133

Fourier transform ion cyclotron resonance precision atomic mass measurement limits  

SciTech Connect

The application of Fourier Transform Ion Cylcotron Resonance Mass Spectroscopy to precision atomic mass measurements is considered. Limits on the mass accuracy of this technique for atomic masses are discussed, and plans for future developments with application to fundamental weak interaction physics are presented.

Kouzes, R.T.

1992-07-01

134

Redundancy, the Discrete Fourier Transform, and Impulse Noise Cancellation  

Microsoft Academic Search

The relationship between the discrete Fourier transform and error-control codes is examined. Under certain conditions we show that discrete-time sequences carry redundant information which then allow for the detection and correction of errors. An application of this technique to impulse noise cancellation for pulse amplitude modulation transmission is described.

J. Wolf

1983-01-01

135

A prescription of Winograd's discrete Fourier transform algorithm  

NASA Technical Reports Server (NTRS)

A detailed and complete description of Winograd's discrete Fourier transform algorithm (DFT) is presented omitting all proofs and derivations. The algorithm begins with the transfer of data from the input vector array to the working array where the actual transformation takes place, otherwise known as input scrambling and output unscrambling. The third array holds constraints required in the transformation stage that are evaluated in the precomputation stage. The algorithm is made up of several FORTRAN subroutines which are not to be confused with practical software algorithmic implementation since they are designed for clarity and not for speed.

Zohar, S.

1979-01-01

136

A Student's Guide to Fourier Transforms - 2nd Edition  

NASA Astrophysics Data System (ADS)

Fourier transform theory is of central importance in a vast range of applications in physical science, engineering, and applied mathematics. This new edition of a successful student text provides a concise introduction to the theory and practice of Fourier transforms, using qualitative arguments wherever possible and avoiding unnecessary mathematics. After a brief description of the basic ideas and theorems, the power of the technique is then illustrated by referring to particular applications in optics, spectroscopy, electronics and telecommunications. The rarely discussed but important field of multi-dimensional Fourier theory is covered, including a description of computer-aided tomography (CAT-scanning). The final chapter discusses digital methods, with particular attention to the fast Fourier transform. Throughout, discussion of these applications is reinforced by the inclusion of worked examples. The book assumes no previous knowledge of the subject, and will be invaluable to students of physics, electrical and electronic engineering, and computer science. Expanded to include more emphasis on applications An established successful textbook for undergraduate and graduate students Includes worked examples and copious diagrams throughout

James, J. F.

2002-09-01

137

A VLSI architecture for simplified arithmetic Fourier transform algorithm  

NASA Technical Reports Server (NTRS)

The arithmetic Fourier transform (AFT) is a number-theoretic approach to Fourier analysis which has been shown to perform competitively with the classical FFT in terms of accuracy, complexity, and speed. Theorems developed in a previous paper for the AFT algorithm are used here to derive the original AFT algorithm which Bruns found in 1903. This is shown to yield an algorithm of less complexity and of improved performance over certain recent AFT algorithms. A VLSI architecture is suggested for this simplified AFT algorithm. This architecture uses a butterfly structure which reduces the number of additions by 25 percent of that used in the direct method.

Reed, Irving S.; Shih, Ming-Tang; Truong, T. K.; Hendon, E.; Tufts, D. W.

1992-01-01

138

Fourier transforms and fractals in the food and agricultural industry  

NASA Astrophysics Data System (ADS)

Links between the fractal Hausdorff-dimension, the Fourier transform of 2D scenes and image segmentation by texture are discussed. It is shown that the fractal Hausdorff-dimension can be derived by integration of the intensity of the spatial frequency domain (i.e. the Fourier plane) over a set of different band-limited spatial filters. The difference between a computational and optical approach to determine the Hausdorff-dimension are shown, with advantages of both methods discussed. Possible future directions of research/improvements are mentioned. Natural and simulated scenes are considered which apply to a wide range of situations in the agricultural and food industry.

Zwiggelaar, Reyer; Bull, Christine R.

1994-11-01

139

Modified Fourier-Hankel method based on analysis of errors in Abel inversion using Fourier transform techniques  

Microsoft Academic Search

Errors in discrete Abel inversion methods using Fourier transform techniques have been analyzed. The Fourier expansion method is very accurate but sensitive to noise. The Fourier-Hankel method has a significant systematic negative deviation, which increases with the radius; inversion error of the method can be reduced by adjusting the value of a factor. With a decrease of the factor both

Shuiliang Ma; Hongming Gao; Lin Wu

2008-01-01

140

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. PMID:23262541

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

2013-01-01

141

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

142

Un algorithme de transformation de Fourier rapide à double base  

Microsoft Academic Search

\\u000a Analyse  Cet article décrit un algorithme de transformation de Fourier rapide proposé récemment, qui présente des avantages en complexité\\u000a de calcul, occupation mémoire et régularité de structure. Après avoir brièvement décrit l’algorithme à double base dans le\\u000a cas de signaux complexes, l’application aux cas de signaux réels et réels symétriques est examinée, ainsi que le lien avec\\u000a un algorithme optimal quant

Pierre Duhamel

1985-01-01

143

Dispersive fourier transform far-infrared spectroscopy of aliphatic ketones  

Microsoft Academic Search

A dispersive Fourier transform far-infrared spectrometer is used to measure the optical constants (absorption and refractive index) of a number of aliphatic ketones, in the wave number range 20–500 cm?1. Several previously unreported absorption features of aliphatic ketones at far-infrared frequencies above the Poley region are found. Frequencies of some of the bands are shown to coincide with those calculated

Patrick F. Corcoran; Jagdish K. Vij; Tatiana S. Perova

1995-01-01

144

An Orthogonally Multiplexed QAM System Using the Discrete Fourier Transform  

Microsoft Academic Search

An orthogonally multiplexed QAM (O-QAM) system is a multichannel system with a baud rate spacing between adjacent carrier frequencies; this property is desirable to digitally implement the system using the discrete Fourier transformation (DFT). This paper provides a novel digital signal processing method based on anN\\/2-point DFT processing in the O-QAM system. A complexity comparison between a digital O-QAM system

BOTARO HIROSAKI

1981-01-01

145

The industrial value of Fourier Transform Raman spectroscopy  

NASA Astrophysics Data System (ADS)

Fourier Transform Raman accessories are offered by most of the FTIR manufacturers and provide versatile Raman facilities which are unequally easy to use. Applications of this new technology in a wide range of industrially significant areas are discussed including inorganic and organic analysis, pharmaceutical and forensic science, the study and analysis of polymers including elastomers and paints. Examples of species sorbed to electrodes and catalysts are then discussed.

Hendra, Patrick J.

1992-03-01

146

Industrial applications of open-path Fourier transform infrared spectrometry  

NASA Astrophysics Data System (ADS)

A commercially available fieldable Fourier transform infrared (FT-IR) spectrometer has been evaluated for monitoring volatile organic compounds (VOCs) in and around incineration equipment for VOC emissions. During this data collection a 20 X 20 inch polished stainless steel plate was used as the reflection surface, to evaluate the use of less expansive optics for industrial applications. Research has also progressed on developing a method to produce an I0 spectrum utilizing a short path length.

Spartz, Martin L.; Eldridge, Jess S.; Hipple, Gary D.; Reagen, William K.; Stock, Jeffrey W.

1994-01-01

147

Fourier transform profilometry by using digital dc subtraction  

NASA Astrophysics Data System (ADS)

A new method for eliminating unwanted background of Fourier transform profilometry (FTP) by using simple dc bias and background eliminations from the deformed grating images is proposed. The proposed method has an advantage over a conventional FTP in that the 3-D object profile can be accurately measured although original fundamental spectra are corrupted by a zeroth-order spectrum. Experimental verifications of the proposed method are presented.

Wongjarern, J.; Widjaja, J.; Sangpech, W.; Thongdee, N.; Santisoonthornwat, P.; Traisak, O.; Chuamchaitrakool, P.; Meemon, P.

2014-06-01

148

Fast Fourier transform analysis of rotor-bearing systems  

NASA Technical Reports Server (NTRS)

Nonlinear transient analysis of rotor-bearing systems is becoming increasingly important in the analysis of modern-day rotating machinery to model such phenomena as oil film whirl. This paper develops an analysis technique incorporating modal analysis and fast Fourier transform techniques to analyze rotors with residual shaft bow and realistic nonlinear bearings. The technique is demonstrated on single-mass and three-mass rotor examples. Comparisons of the theoretical results with experimental data give excellent agreement.

Choy, K. C.; Gunter, E. J.; Allaire, P. E.

1978-01-01

149

The determination of peroxide value by fourier transform infrared spectroscopy  

Microsoft Academic Search

A rapid method for the quantitative determination of peroxide value (PV) of vegetable oils by Fourier transform infrared (FTIR)\\u000a transmission spectroscopy is described. Calibration standards were prepared by the addition oft-butyl hydroperoxide to a series of vegetable oils, along with random amounts of oleic acid and water. Additional standards\\u000a were derived through the addition of mono- and diglyceride spectral contributions,

F. R. van de Voort; A. A. Ismail; J. Sedman; J. Dubois; T. Nicodemo

1994-01-01

150

Fourier spectroscopy with a one-million-point transformation  

NASA Technical Reports Server (NTRS)

A new type of interferometer for use in Fourier spectroscopy has been devised at the Aime Cotton Laboratory of the National Center for Scientific Research (CNRS), Orsay, France. With this interferometer and newly developed computational techniques, interferograms comprising as many as one million samples can now be transformed. The techniques are described, and examples of spectra of thorium and holmium, derived from one million-point interferograms, are presented.

Connes, J.; Delouis, H.; Connes, P.; Guelachvili, G.; Maillard, J.; Michel, G.

1972-01-01

151

Mass Spectral Peak Distortion Due to Fourier Transform Signal Processing  

NASA Astrophysics Data System (ADS)

Distortions of peaks can occur when one uses the standard method of signal processing of data from the Orbitrap and other FT-based methods of mass spectrometry. These distortions arise because the standard method of signal processing is not a linear process. If one adds two or more functions, such as time-dependent signals from a Fourier transform mass spectrometer and performs a linear operation on the sum, the result is the same as if the operation was performed on separate functions and the results added. If this relationship is not valid, the operation is non-linear and can produce unexpected and/or distorted results. Although the Fourier transform itself is a linear operator, the standard algorithm for processing spectra in Fourier transform-based methods include non-linear mathematical operators such that spectra processed by the standard algorithm may become distorted. The most serious consequence is that apparent abundances of the peaks in the spectrum may be incorrect. In light of these considerations, we performed theoretical modeling studies to illustrate several distortion effects that can be observed, including abundance distortions. In addition, we discuss experimental systems where these effects may manifest, including suggested systems for study that should demonstrate these peak distortions. Finally, we point to several examples in the literature where peak distortions may be rationalized by the phenomena presented here.

Rockwood, Alan L.; Erve, John C. L.

2014-12-01

152

Wavelength-encoded tomography based on optical temporal Fourier transform  

NASA Astrophysics Data System (ADS)

We propose and demonstrate a technique called wavelength-encoded tomography (WET) for non-invasive optical cross-sectional imaging, particularly beneficial in biological system. The WET utilizes time-lens to perform the optical Fourier transform, and the time-to-wavelength conversion generates a wavelength-encoded image of optical scattering from internal microstructures, analogous to the interferometery-based imaging such as optical coherence tomography. Optical Fourier transform, in principle, comes with twice as good axial resolution over the electrical Fourier transform, and will greatly simplify the digital signal processing after the data acquisition. As a proof-of-principle demonstration, a 150 -?m (ideally 36 ?m) resolution is achieved based on a 7.5-nm bandwidth swept-pump, using a conventional optical spectrum analyzer. This approach can potentially achieve up to 100-MHz or even higher frame rate with some proven ultrafast spectrum analyzer. We believe that this technique is innovative towards the next-generation ultrafast optical tomographic imaging application.

Zhang, Chi; Wong, Kenneth K. Y.

2014-09-01

153

UNIQUENESS RESULTS FOR THE PHASE RETRIEVAL PROBLEM OF FRACTIONAL FOURIER TRANSFORMS OF VARIABLE ORDER  

E-print Network

problem for the fractional Fourier transform (FrFT) of variable order. This problem occurs naturally and phrases. Phase retrieval; Pauli problem; Fractional Fourier transform; entire function of finite order. 1UNIQUENESS RESULTS FOR THE PHASE RETRIEVAL PROBLEM OF FRACTIONAL FOURIER TRANSFORMS OF VARIABLE

Paris-Sud XI, Université de

154

Quasiparticle relaxation in Heavy Fermions studied using Inverse Fourier Transform of optical conductivity  

E-print Network

Quasiparticle relaxation in Heavy Fermions studied using Inverse Fourier Transform of optical Keywords: Optical conductivity Inverse Fourier Transform Heavy Fermions a b s t r a c t Inverse Fourier Transform of optical conductivity is used for studies of quasiparticle relaxation in Heavy Fermions in time

Dordevic, Sasha V.

155

Radon and Fourier transforms for D-modules Andrea D'Agnolo  

E-print Network

Radon and Fourier transforms for D-modules Andrea D'Agnolo and Michael Eastwood Version: July 17, 2002 Contents 1 Radon and Fourier transforms for D-modules 3 1.1 Review on algebraic D-modules . . . . . . . . . . . . . . . . 3 1.2 Review on the Fourier-Laplace transform . . . . . . . . . . 5 1.3 Review on the Radon

D'Agnolo, Andrea

156

Improved digital filters for evaluating Fourier and Hankel transform integrals  

USGS Publications Warehouse

New algorithms are described for evaluating Fourier (cosine, sine) and Hankel (J0,J1) transform integrals by means of digital filters. The filters have been designed with extended lengths so that a variable convolution operation can be applied to a large class of integral transforms having the same system transfer function. A f' lagged-convolution method is also presented to significantly decrease the computation time when computing a series of like-transforms over a parameter set spaced the same as the filters. Accuracy of the new filters is comparable to Gaussian integration, provided moderate parameter ranges and well-behaved kernel functions are used. A collection of Fortran IV subprograms is included for both real and complex functions for each filter type. The algorithms have been successfully used in geophysical applications containing a wide variety of integral transforms

Anderson, Walter L.

1975-01-01

157

Quantum-Beat Free-Induction Decay of Copper Ions in an Aqueous Solution: FourierTransform ESR Spectroscopy by Optical Means  

Microsoft Academic Search

The fast-spin dynamics of transition-metal ions in an aqueous solution at room temperature has been directly observed in the subnanosecond region by polarization spectroscopy using the pump-probe technique. The time evolution of the optically induced magnetization is monitored through the change in the polarization of the probe pulse. Quantum-beat free-induction decay signals in the ground state of copper ions in

Shigenori Furue; Kazuyuki Nakayama; Toshiro Kohmoto; Masakazu Kunitomo; Yukio Fukuda

2004-01-01

158

The conformational analysis of push-pull enaminones using Fourier transform IR and NMR spectroscopy, and quantum chemical calculations. V. ?-Methyl-, fluorine-?-N,N-dimethylaminovinyl trifluoromethyl ketones  

NASA Astrophysics Data System (ADS)

IR Fourier spectra of two enaminoketones with general formula F3Csbnd COsbnd CRdbnd CHsbnd N(CH3)2, R = F (DMTFBN); R = CH3, (DMTMBN) were studied in various pure solvents. For comparison results of earlier investigated enaminoketone R = H (DMTBN) was also presented. On the basis of NMR and IR spectra it was shown that enaminoketones DMTBN, DMTFBN and DMTMBN presented in solutions as equilibrium of two conformers, (E-s-Z) ? (E-s-E) (for DMTFBN these conformers are denoted as (Z-s-Z) and (Z-s-E), respectively). DFT calculations were carried out to evaluate relative energy and dipole moment of each spatial form. It was shown that ‘closed-ring' complex formation between (E-s-Z) and (E-s-E) conformers of DMTBN accounts for discrepancies between DFT calculations of conformer relative energies and experimentally evaluated enthalpies of (E-s-Z) ? (E-s-E) equilibrium. In ?-substituted DMTFBN and DMTMBN, where formation of ‘closed-ring' complex was impossible we did not observe such discrepancies. For both (E-s-Z) and (E-s-E) conformers of the DMTBN and DMTMBN the main influence on the ?˜(Cdbnd O) vibrations has the solvent's hydrogen bond donor (HBD) acidity, whereas for the DMTFBN an influence of the solvent's polarity/polarizability dominated.

Vdovenko, Sergey I.; Gerus, Igor I.; Zhuk, Yuri I.; Kukhar, Valery P.; Röschenthaler, Gerd-Volker

2014-10-01

159

The conformational analysis of push-pull enaminones using Fourier transform IR and NMR spectroscopy, and quantum chemical calculations. V. ?-Methyl-, fluorine-?-N,N-dimethylaminovinyl trifluoromethyl ketones.  

PubMed

IR Fourier spectra of two enaminoketones with general formula F3CCOCRCHN(CH3)2, R=F (DMTFBN); R=CH3, (DMTMBN) were studied in various pure solvents. For comparison results of earlier investigated enaminoketone R=H (DMTBN) was also presented. On the basis of NMR and IR spectra it was shown that enaminoketones DMTBN, DMTFBN and DMTMBN presented in solutions as equilibrium of two conformers, (E-s-Z)?(E-s-E) (for DMTFBN these conformers are denoted as (Z-s-Z) and (Z-s-E), respectively). DFT calculations were carried out to evaluate relative energy and dipole moment of each spatial form. It was shown that 'closed-ring' complex formation between (E-s-Z) and (E-s-E) conformers of DMTBN accounts for discrepancies between DFT calculations of conformer relative energies and experimentally evaluated enthalpies of (E-s-Z)?(E-s-E) equilibrium. In ?-substituted DMTFBN and DMTMBN, where formation of 'closed-ring' complex was impossible we did not observe such discrepancies. For both (E-s-Z) and (E-s-E) conformers of the DMTBN and DMTMBN the main influence on the ??(CO) vibrations has the solvent's hydrogen bond donor (HBD) acidity, whereas for the DMTFBN an influence of the solvent's polarity/polarizability dominated. PMID:24820327

Vdovenko, Sergey I; Gerus, Igor I; Zhuk, Yuri I; Kukhar, Valery P; Röschenthaler, Gerd-Volker

2014-10-15

160

Partial differential equation transform — Variational formulation and Fourier analysis  

PubMed Central

Nonlinear partial differential equation (PDE) models are established approaches for image/signal processing, data analysis and surface construction. Most previous geometric PDEs are utilized as low-pass filters which give rise to image trend information. In an earlier work, we introduced mode decomposition evolution equations (MoDEEs), which behave like high-pass filters and are able to systematically provide intrinsic mode functions (IMFs) of signals and images. Due to their tunable time-frequency localization and perfect reconstruction, the operation of MoDEEs is called a PDE transform. By appropriate selection of PDE transform parameters, we can tune IMFs into trends, edges, textures, noise etc., which can be further utilized in the secondary processing for various purposes. This work introduces the variational formulation, performs the Fourier analysis, and conducts biomedical and biological applications of the proposed PDE transform. The variational formulation offers an algorithm to incorporate two image functions and two sets of low-pass PDE operators in the total energy functional. Two low-pass PDE operators have different signs, leading to energy disparity, while a coupling term, acting as a relative fidelity of two image functions, is introduced to reduce the disparity of two energy components. We construct variational PDE transforms by using Euler-Lagrange equation and artificial time propagation. Fourier analysis of a simplified PDE transform is presented to shed light on the filter properties of high order PDE transforms. Such an analysis also offers insight on the parameter selection of the PDE transform. The proposed PDE transform algorithm is validated by numerous benchmark tests. In one selected challenging example, we illustrate the ability of PDE transform to separate two adjacent frequencies of sin(x) and sin(1.1x). Such an ability is due to PDE transform’s controllable frequency localization obtained by adjusting the order of PDEs. The frequency selection is achieved either by diffusion coefficients or by propagation time. Finally, we explore a large number of practical applications to further demonstrate the utility of proposed PDE transform. PMID:22207904

Wang, Yang; Wei, Guo-Wei; Yang, Siyang

2011-01-01

161

Radon and Fourier transforms for Dmodules Andrea D'Agnolo and Michael Eastwood  

E-print Network

Radon and Fourier transforms for D­modules Andrea D'Agnolo and Michael Eastwood Contents Introduction 2 Acknowledgements 2 1. Radon and Fourier transforms for D­modules 3 1.1. Review on algebraic D­modules 3 1.2. Review on the Fourier­Laplace transform 5 1.3. Review on the Radon transform(s) 6 1.4. Review

162

Versatile and Sensitive Dual Comb Fourier Transform Spectroscopy  

NASA Astrophysics Data System (ADS)

Fourier transform spectroscopy based on time-domain interferences between two slightly detuned frequency comb sources holds much promise for the real-time diagnostic of gaseous, liquid or solid-state samples. In one very recent example, cavity-enhanced absorption spectroscopy with two infrared frequency combs has demonstrated a dramatically enhanced sensitivity, compared to conventional Fourier spectroscopy, with intriguing implications for instantaneous trace gas analysis. It however remains challenging to match continuously the comb and cavity modes across a broad spectral bandwidth during the time of a measurement. An obvious alternative for reaching a long interaction path is a conventional multipass cell. Additionally, differential detection schemes may be devised to increase the dynamic range of the interferometric measurements, thus providing enhanced signal to noise ratio. Experimental demonstrations will be given in the 1.5 ?m region with a dual comb set-up based on two Er-doped fiber femtosecond lasers. The versatility and performances of these solutions will be compared to the cavity-enhanced dual comb technique and other state-of-the-art alternatives. P. Jacquet, J. Mandon, B. Bernhardt, R. Holzwarth, G. Guelachvili, T. W. Hänsch, N. Picqué, Frequency Comb Fourier Transform Spectroscopy with kHz Optical Resolution, The Optical Society of America, Washington, DC 2009, paper FMB2 (2009). B. Bernhardt, A. Ozawa, P. Jacquet, M. Jacquey, Y. Kobayashi, T. Udem, R. Holzwarth, G. Guelachvili, T.W. Hänsch, N. Picqué, Cavity-enhanced dual-comb spectroscopy, Nature Photonics 4, 55-57 (2010),

Jacquey, M.; Jacquet, P.; Mandon, J.; Thon, R.; Guelachvili, G.; Hänsch, T. W.; Picqué, N.

2010-06-01

163

Two-Dimensional Fourier Transform Analysis of Helicopter Flyover Noise  

NASA Technical Reports Server (NTRS)

A method to separate main rotor and tail rotor noise from a helicopter in flight is explored. Being the sum of two periodic signals of disproportionate, or incommensurate frequencies, helicopter noise is neither periodic nor stationary. The single Fourier transform divides signal energy into frequency bins of equal size. Incommensurate frequencies are therefore not adequately represented by any one chosen data block size. A two-dimensional Fourier analysis method is used to separate main rotor and tail rotor noise. The two-dimensional spectral analysis method is first applied to simulated signals. This initial analysis gives an idea of the characteristics of the two-dimensional autocorrelations and spectra. Data from a helicopter flight test is analyzed in two dimensions. The test aircraft are a Boeing MD902 Explorer (no tail rotor) and a Sikorsky S-76 (4-bladed tail rotor). The results show that the main rotor and tail rotor signals can indeed be separated in the two-dimensional Fourier transform spectrum. The separation occurs along the diagonals associated with the frequencies of interest. These diagonals are individual spectra containing only information related to one particular frequency.

SantaMaria, Odilyn L.; Farassat, F.; Morris, Philip J.

1999-01-01

164

Coherent electromagnetic field imaging through Fourier transform heterodyne  

SciTech Connect

The authors present a detection process capable of directly imaging the transverse amplitude, phase, and if desired, Doppler shift of coherent electromagnetic fields. Based on coherent detection principles governing conventional heterodyned RADAR/LIDAR systems, Fourier Transform Heterodyne (FTH) incorporates transverse spatial encoding of the local oscillator for image capture. Appropriate selection of spatial encoding functions, or basis set, allows image retrieval by way of classic Fourier manipulations. Of practical interest: (1) imaging is accomplished on a single element detector requiring no additional scanning or moving components, and (2) a wide variety of appropriate spatial encoding functions exist that may be adaptively configured in real-time for applications requiring optimal detection. In this paper, they introduce the underlying principles governing FTH imaging, followed by demonstration of concept via a simple experimental setup based on a HeNe laser and a 69 element spatial phase modulator.

Cooke, B.J.; Laubscher, B.E.; Olivas, N.L.; Goeller, R.M.; Cafferty, M.; Briles, S.D. [Los Alamos National Lab., NM (United States); Galbraith, A.E. [Los Alamos National Lab., NM (United States)]|[Univ. of Arizona, Tucson, AZ (United States). Electrical and Computer Engineering Dept.; Grubler, A.C. [Los Alamos National Lab., NM (United States)]|[Naval Academy, Annapolis, MD (United States)

1998-12-31

165

Fourier transform spectrometry for fiber-optic sensor systems  

NASA Technical Reports Server (NTRS)

An integrated-optic Mach-Zehnder interferometer is used as a Fourier transform spectrometer to analyze the input and output spectra of a temperature-sensing thin-film etalon. This type of spectrometer has an advantage over conventional grating spectrometers because it is better suited for use with time-division-multiplexed sensor networks. In addition, this spectrometer has the potential for low cost due to its use of a component that could be manufactured in large quantities for the optical communications industry.

Beheim, Glenn; Tuma, Margaret L.; Sotomayor, Jorge L.; Flatico, Joseph M.

1993-01-01

166

SCUBA-2 Fourier transform spectrometer (FTS-2) commissioning results  

NASA Astrophysics Data System (ADS)

We present the latest commissioning results and instrument performance for the SCUBA-2 imaging Fourier Transform Spectrometer (FTS-2) installed at the James Clerk Maxwell Telescope (JCMT). This ancillary instrument provides intermediate spectral resolution (R ~10 to 5000) across both the 450 and 850 ?m atmospheric transmission windows with a FOV of ~5 arcmin2. The superconducting TES sensors and SQUID readout of SCUBA-2 present unique challenges for operation of an FTS; the sensitivity requirements demand high detector linearity and stability in addition to control of systematic atmospheric and optical spillover effects. We discuss the challenges encountered during commissioning and ongoing efforts to mitigate their effects.

Gom, Brad G.; Naylor, David A.; Friberg, Per; Bell, Graham S.; Bintley, Daniel; Abdelazim, Sherif; Sherwood, Matt

2014-07-01

167

Synthetic quadrature phase detector/demodulator for Fourier transform spectrometers.  

PubMed

A method is developed to demodulate (velocity correct) Fourier transform spectrometer data that are taken with an analog to digital converter that digitizes equally spaced in time. This method makes it possible to use simple low-cost, high-resolution audio digitizers to record high-quality data without the need for an event timer or quadrature laser hardware and makes it possible to use a metrology laser of any wavelength. The reduced parts count and simple implementation make it an attractive alternative in space-based applications when compared to previous methods such as the Brault algorithm. PMID:19104542

Campbell, Joel

2008-12-20

168

Fizeau Fourier transform imaging spectroscopy: missing data reconstruction.  

PubMed

Fizeau Fourier transform imaging spectroscopy yields both spatial and spectral information about an object. Spectral information, however, is not obtained for a finite area of low spatial frequencies. A nonlinear reconstruction algorithm based on a gray-world approximation is presented. Reconstruction results from simulated data agree well with ideal Michelson interferometer-based spectral imagery. This result implies that segmented-aperture telescopes and multiple telescope arrays designed for conventional imaging can be used to gather useful spectral data through Fizeau FTIS without the need for additional hardware. PMID:18545367

Thurman, Samuel T; Fienup, James R

2008-04-28

169

Fourier Transform Infrared Spectroscopy for Process Monitoring and Control  

E-print Network

by the U.S. Department of Energy under Contract No. DE ACOI-88ER8056, Mr. Stanley Sobczynski, Contract Monitor and under NSF Grant No. i119260037, Dr. Edward Dryan, Contract Monitor. The authors would also like to thank Peter Thorn, Pierre Leroueil... , Fuel, 60, 263-266, (1981). 3. Morrison, P.W. Jr., Solomon, P.R., Serio, M.A., Carangelo, R.M., and Markham, J.R., wFourier Transform Infrared Spectroscopy for Process Monitoring Part I: Theory & Part ll; Applications w , Sensors, 8, (12) 32...

Solomon, P. R.; Carangelo, M. D.; Carangelo, R. M.

170

Transfer Function Identification Using Orthogonal Fourier Transform Modeling Functions  

NASA Technical Reports Server (NTRS)

A method for transfer function identification, including both model structure determination and parameter estimation, was developed and demonstrated. The approach uses orthogonal modeling functions generated from frequency domain data obtained by Fourier transformation of time series data. The method was applied to simulation data to identify continuous-time transfer function models and unsteady aerodynamic models. Model fit error, estimated model parameters, and the associated uncertainties were used to show the effectiveness of the method for identifying accurate transfer function models from noisy data.

Morelli, Eugene A.

2013-01-01

171

Fourier Transform Microwave Spectrum of MgCCH (X2?^+)  

NASA Astrophysics Data System (ADS)

The pure rotational spectrum of MgCCH (X2?^+) in the frequency range of 9-40 GHz has been measured using Fourier transform microwave (FTMW) methods. The molecule was synthesized using discharge assisted laser ablation spectroscopy (DALAS) from a mixture of 0.1% acetylene in argon and the ablation of a magnesium rod. From these data, the hydrogen hyperfine parameters have been determined for the first time, as well as refinement of the rotational and spin-rotational constants, combined with previous millimeter-wave spectra measured by the Ziurys group.

Min, J.; Halfen, D. T.; Sun, M.; Hariss, B. T.; Ziurys, L. M.; Clouthier, D. J.

2011-06-01

172

Particle field holography data reduction by Fourier transform analysis  

NASA Technical Reports Server (NTRS)

The size distribution of a particle field hologram is obtained with a Fourier transformation of the Fraunhofer diffraction pattern of the reconstructed hologram. Off-axis absorption holograms of particle fields with known characteristics were obtained and analyzed with a commercially available instrument. The mean particle size of the reconstructed hologram was measured with an error of + or - 5 percent, while the distribution broadening was estimated within + or - 15 percent. Small sections of a pulsed laser hologram of a synthetic fuel spray were analyzed with this method thus yielding a spatially resolved size distribution. The method yields fast and accurate automated analysis of particle field holograms.

Hess, Cecil F.; Trolinger, James D.

1987-01-01

173

Fourier-transform Raman spectroscopic study of human hair  

NASA Astrophysics Data System (ADS)

Fourier-transform Raman microscopic spectra of normal, untreated and bleached hair fibres are presented. Vibrational assignments are made and differences are ascribed to the production of cysteic acid from cysteine. Changes in conformation associated with the disulphide bond in the keratotic component are noted from the ?(CSSC) vibrational modes at wave numbers near 500 cm -1. Raman spectra of hair root ends have also been investigated with a diminution in cysteine content being observed. Application of the technique to the biomedical investigation of healthy and diseased hair is proposed.

Akhtar, W.; Edwards, H. G. M.; Farwell, D. W.; Nutbrown, M.

1997-07-01

174

Data Transmission by Frequency-Division Multiplexing Using the Discrete Fourier Transform  

Microsoft Academic Search

The Fourier transform data communication system is a realization of frequency-division multiplexing (FDM) in which discrete Fourier transforms are computed as part of the modulation and demodulation processes. In addition to eliminating the bunks of subcarrier oscillators and coherent demodulators usually required in FDM systems, a completely digital implementation can be built around a special-purpose computer performing the fast Fourier

S. B. WEINSTEIN; PAUL M. EBERT

1971-01-01

175

2D Discrete Fourier Transform on Sliding Windows.  

PubMed

Discrete Fourier transform (DFT) is the most widely used method for determining the frequency spectra of digital signals. In this paper, a 2D sliding DFT (2D SDFT) algorithm is proposed for fast implementation of the DFT on 2D sliding windows. The proposed 2D SDFT algorithm directly computes the DFT bins of the current window using the precalculated bins of the previous window. Since the proposed algorithm is designed to accelerate the sliding transform process of a 2D input signal, it can be directly applied to computer vision and image processing applications. The theoretical analysis shows that the computational requirement of the proposed 2D SDFT algorithm is the lowest among existing 2D DFT algorithms. Moreover, the output of the 2D SDFT is mathematically equivalent to that of the traditional DFT at all pixel positions. PMID:25585421

Park, Chun-Su

2015-03-01

176

Fourier Transform for Fermionic Systems and the Spectral Tensor Network  

NASA Astrophysics Data System (ADS)

Leveraging the decomposability of the fast Fourier transform, I propose a new class of tensor network that is efficiently contractible and able to represent many-body systems with local entanglement that is greater than the area law. Translationally invariant systems of free fermions in arbitrary dimensions as well as 1D systems solved by the Jordan-Wigner transformation are shown to be exactly represented in this class. Further, it is proposed that these tensor networks be used as generic structures to variationally describe more complicated systems, such as interacting fermions. This class shares some similarities with the Evenbly-Vidal branching multiscale entanglement renormalization ansatz, but with some important differences and greatly reduced computational demands.

Ferris, Andrew J.

2014-07-01

177

Soft x-ray microscope using Fourier transform holography  

SciTech Connect

A Fourier transform holographic microscope with an anticipated resolution of better than 100 nm has been built. Extensive testing of the apparatus has begun. Preliminary results include the recording of interference fringes using 3.6 nm x-rays. The microscope employs a charge-coupled device (CCD) detector array of 576 {times} 384 elements. The system is illuminated by soft x-rays from a high brightness undulator. The reference point source is formed by a Fresnel zone plate with a finest outer zone width of 50 nm. Sufficient temporal coherence for hologram formation is obtained by a spherical grating monochromator. The x-ray hologram intensities at the recording plane are to be collected, digitized and reconstructed by computer. Data acquisition is under CAMAC control, while image display and off-line processing takes place on a VAX graphics workstation. Computational models of Fourier transform hologram synthesis, and reconstruction in the presence of noise, have demonstrated the feasibility of numerical methods in two dimensions, and that three-dimensional information is potentially recoverable. 13 refs., 3 figs.

McNulty, I.; Kirz, J.; Jacobsen, C.; Anderson, E.; Howells, M.R.; Rarback, H. (State Univ. of New York, Stony Brook, NY (USA). Dept. of Physics; Lawrence Berkeley Lab., CA (USA); Brookhaven National Lab., Upton, NY (USA))

1989-01-01

178

Radial Hilbert Transform in terms of the Fourier Transform applied to Image Encryption  

NASA Astrophysics Data System (ADS)

In the present investigation, a mathematical algorithm under Matlab platform using Radial Hilbert Transform and Random Phase Mask for encrypting digital images is implemented. The algorithm is based on the use of the conventional Fourier transform and two random phase masks, which provide security and robustness to the system implemented. Random phase masks used during encryption and decryption are the keys to improve security and make the system immune to attacks by program generation phase masks.

Morales, Y.; Díaz, L.; Torres, C.

2015-01-01

179

Modified Fourier-Hankel method based on analysis of errors in Abel inversion using Fourier transform techniques  

NASA Astrophysics Data System (ADS)

Errors in discrete Abel inversion methods using Fourier transform techniques have been analyzed. The Fourier expansion method is very accurate but sensitive to noise. The Fourier-Hankel method has a significant systematic negative deviation, which increases with the radius; inversion error of the method can be reduced by adjusting the value of a factor. With a decrease of the factor both methods show a noise filtering property. Based on the analysis, a modified Fourier-Hankel method that is accurate, computationally efficient, and has the ability to filter noise in the inversion process is proposed for applying to experimental data.

Ma, Shuiliang; Gao, Hongming; Wu, Lin

2008-03-01

180

Modified Fourier-Hankel method based on analysis of errors in Abel inversion using Fourier transform techniques.  

PubMed

Errors in discrete Abel inversion methods using Fourier transform techniques have been analyzed. The Fourier expansion method is very accurate but sensitive to noise. The Fourier-Hankel method has a significant systematic negative deviation, which increases with the radius; inversion error of the method can be reduced by adjusting the value of a factor. With a decrease of the factor both methods show a noise filtering property. Based on the analysis, a modified Fourier-Hankel method that is accurate, computationally efficient, and has the ability to filter noise in the inversion process is proposed for applying to experimental data. PMID:18709083

Ma, Shuiliang; Gao, Hongming; Wu, Lin

2008-03-20

181

GENERIC QUANTUM FOURIER TRANSFORMS Cristopher Moore  

E-print Network

groupes : W Groupe des morceaux qui nécessitent un temps de cuisson court (de l'ordre de 25 à 30 minutes pour i kg de viande). 2° Groupe des morceaux qui nécessitent un temps de cuisson long (2-3 heures ou

Rockmore, Dan

182

Polarization-dependent optical 2D Fourier transform spectroscopy of semiconductors  

PubMed Central

Optical 2D Fourier transform spectroscopy (2DFTS) provides insight into the many-body interactions in direct gap semiconductors by separating the contributions to the coherent nonlinear optical response. We demonstrate these features of optical 2DFTS by studying the heavy-hole and light-hole excitonic resonances in a gallium arsenide quantum well at low temperature. Varying the polarization of the incident beams exploits selection rules to achieve further separation. Calculations using a full many-body theory agree well with experimental results and unambiguously demonstrate the dominance of many-body physics. PMID:17630286

Zhang, Tianhao; Kuznetsova, Irina; Meier, Torsten; Li, Xiaoqin; Mirin, Richard P.; Thomas, Peter; Cundiff, Steven T.

2007-01-01

183

Polarization-dependent optical 2D Fourier transform spectroscopy of semiconductors.  

PubMed

Optical 2D Fourier transform spectroscopy (2DFTS) provides insight into the many-body interactions in direct gap semiconductors by separating the contributions to the coherent nonlinear optical response. We demonstrate these features of optical 2DFTS by studying the heavy-hole and light-hole excitonic resonances in a gallium arsenide quantum well at low temperature. Varying the polarization of the incident beams exploits selection rules to achieve further separation. Calculations using a full many-body theory agree well with experimental results and unambiguously demonstrate the dominance of many-body physics. PMID:17630286

Zhang, Tianhao; Kuznetsova, Irina; Meier, Torsten; Li, Xiaoqin; Mirin, Richard P; Thomas, Peter; Cundiff, Steven T

2007-09-01

184

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

2013-07-25

185

The Empirical Mode Decomposition algorithm via Fast Fourier Transform  

NASA Astrophysics Data System (ADS)

In this paper we consider a problem of implementing a fast algorithm for the Empirical Mode Decomposition (EMD). EMD is one of the newest methods for decomposition of non-linear and non-stationary signals. A basis of EMD is formed "on-the-fly", i.e. it depends from a distribution of the signal and not given a priori in contrast on cases Fourier Transform (FT) or Wavelet Transform (WT). The EMD requires interpolating of local extrema sets of signal to find upper and lower envelopes. The data interpolation on an irregular lattice is a very low-performance procedure. A classical description of EMD by Huang suggests doing this through splines, i.e. through solving of a system of equations. Existence of a fast algorithm is the main advantage of the FT. A simple description of an algorithm in terms of Fast Fourier Transform (FFT) is a standard practice to reduce operation's count. We offer a fast implementation of EMD (FEMD) through FFT and some other cost-efficient algorithms. Basic two-stage interpolation algorithm for EMD is composed of a Upscale procedure through FFT and Downscale procedure through a selection procedure for signal's points. First we consider the local maxima (or minima) set without reference to the axis OX, i.e. on a regular lattice. The Upscale through the FFT change the signal's length to the Least Common Multiple (LCM) value of all distances between neighboring extremes on the axis OX. If the LCM value is too large then it is necessary to limit local set of extrema. In this case it is an analog of the spline interpolation. A demo for FEMD in noise reduction task for OCT has been shown.

Myakinin, Oleg O.; Zakharov, Valery P.; Bratchenko, Ivan A.; Kornilin, Dmitry V.; Artemyev, Dmitry N.; Khramov, Alexander G.

2014-09-01

186

Fourier transform method for imaging atmospheric Cherenkov telescopes  

NASA Astrophysics Data System (ADS)

We propose Fourier transform (hereafter FT) method for processing the images of extensive air showers (EAS) detected by imaging atmospheric Cherenkov telescopes (IACT) used in the very high energy (VHE) gamma-ray astronomy. The method uses a special type of discrete Fourier transforms (DFT) based on orbit functions of compact Lie groups, and the use of continuous extension of the inverse transform to approximate the discrete images by continuous EAS brightness distribution functions. Here we present the FT-method for SU(3) group which provides a practicable technique for realization of the DFT approach for functions sampled on hexagonal symmetry grids implemented in the current IACT cameras. We note that the proposed FT-method can also be implemented for the rectangular grids using the DFT on SU(2) × SU(2) group. To show the viability of the FT-method, here we apply it to Monte-Carlo simulated bank of TeV proton and gamma-ray EAS images only for the case of a stand-alone telescope and use a simple single-parameter (ALPHA) analysis. Comparing between the FT-method and the currently used ‘standard’ method for signal enhancement shows that a straightforward use of FT technique within standard parameterization scheme allows a better and systematic enhancement of the gamma-ray signal. The relative difference between these two methods becomes more profound especially for ‘photon poor’ images, for which the standard method significantly deteriorates. It suggests that the effective EAS detection thresholds could be reduced with implementation of the FT technique for IACTs. This prediction is further supported by a significant noise suppression capability of the method after using simple ‘low-pass’ filters in the image frequency domain. This new approach allows very deep ‘tail’ (and ‘height’) image cuts, differentiation of images, provides frequency spectra, etc., which could be used for development of new effective parameters for the EAS image processing.

Atoyan, A.; Patera, J.; Sahakian, V.; Akhperjanian, A.

2005-02-01

187

The Radon Transform on SO(3): A Fourier Slice Theorem and  

E-print Network

The Radon Transform on SO(3): A Fourier Slice Theorem and Numerical Inversion R. Hielscher1 , D.Hielscher@helmholz-muenchen.de The inversion of the one­dimensional Radon transform on the rotation group SO(3) is an ill posed inverse problem approach to the numerical inversion of the one­dimensional Radon transform on SO(3). Based on a Fourier

Hielscher, Ralf

188

The Radon Transform on SO(3): A Fourier Slice Theorem and Numerical  

E-print Network

The Radon Transform on SO(3): A Fourier Slice Theorem and Numerical Inversion Ralf Hielscher­dimensional Radon transform on the rotation group SO(3) is an ill posed inverse problem which applies to X inversion of the one­dimensional Radon transform on SO(3). Based on a Fourier slice theorem the discrete

189

International Conference on Fourier Transform Infrared Spectroscopy, University of South Carolina, Columbia, SC, June 8-12, 1981, Proceedings  

Microsoft Academic Search

Applications of Fourier transform infrared spectroscopy to in situ catalyst surface studies are considered along with Fourier transform infrared matrix isolation spectroscopy, Fourier transform far infrared studies of matrix-isolated alcohols, and impurity modes in semiinsulating chromium doped gallium arsenide. Attention is given to an analysis of spectral anomalies in rapid-scanning Fourier transform time-resolved infrared spectrometry, shift reagents in Fourier transform

1981-01-01

190

Generalized prolate spheroidal wave functions for optical finite fractional Fourier and linear canonical transforms  

Microsoft Academic Search

Prolate spheroidal wave functions (PSWFs) are known to be useful for analyzing the properties of the finite-extension Fourier transform (fi-FT). We extend the theory of PSWFs for the finite-extension fractional Fourier transform, the finite-extension linear canonical transform, and the finite-extension offset linear canonical transform. These finite transforms are more flexible than the fi-FT and can model much more generalized optical

Soo-Chang Pei; Jian-Jiun Ding

2005-01-01

191

Spectrochimica Acta Part A 56 (2000) 467473 A modified diffuse reflectance infrared Fourier transform  

E-print Network

(ATR), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and photoacoustic spec not only in terms of their theoretical and physical origin, but also in relation to penetration depth

Mitchell, Brian S.

192

Calibration of the Geostationary Imaging Fourier Transform Spectrometer (GIFTS)  

NASA Technical Reports Server (NTRS)

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 been 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, F. A.; Revercomb, H. E.; Bingham, G. E.; Knuteson, R. O.; Tobin, D. C.; LaPorte, D. D.; Smith, W. L.

2001-01-01

193

Solar radiometry at millimeter wavelengths. [Fast Fourier Transformation solutions  

NASA Technical Reports Server (NTRS)

In the area of resolution enhancement, the use of Fast Fourier Transform programs was investigated for possible application to millimeter wavelength maps of the sun. A difficulty arises with the La Posta maps in that they are limited to 35 arc-minutes square while the smeared out solar image is larger than that. A list of possible cometary emission lines near 13 millimeters is presented. Although preparation of the list was inspired by the appearance of Comet Kohoutek, the results are applicable to any future comet. The brightness temperature of the sun at 8.6 millimeters was measured using the moon as a calibration source. The result does not confirm a deep absorption feature as apparently observed by earlier workers.

Henze, W.

1974-01-01

194

Dealiased spectral images from aliased Fizeau Fourier transform spectroscopy measurements.  

PubMed

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 comparison with the conventional optical transfer function, which is given by the autocorrelation of the entire aperture of the system. The unconventional imaging properties of Fizeau FTIS can be exploited to form spatially dealiased spectral images from undersampled intensity measurements (obtain superresolution relative to the detector pixel spacing). We demonstrate this dealiasing technique through computer simulations and discuss the associated design and operational trade-offs. PMID:17164844

Thurman, Samuel T; Fienup, James R

2007-01-01

195

Discrimination of different Chrysanthemums with Fourier transform infrared spectroscopy  

NASA Astrophysics Data System (ADS)

Use Fourier transform infrared spectroscopy (FT-IR) to analyze simultaneously the main chemical constituents in different solvent extracts of seven kinds of Chrysanthemum samples of different regions. The findings indicate that different Chrysanthemum samples have dissimilar fingerprint characters in FT-IR spectra. Such spectral technique can provide substance structural information of the complicated test samples. According to these spectral fingerprint features, we cannot only identify the main components of different extracts, but also distinguish the origins of the Chrysanthemum samples from different regions easily, which is a troublesome work by existing analytical methods. FT-IR, with the characters of speediness, good repeatability and easy operation, can be used as an effective analytical means to study the complicated system, in our research, the tradition Chinese medicines.

Liu, Hong-xia; Zhou, Qun; Sun, Su-qin; Bao, Hong-juan

2008-07-01

196

Seismic data denoising based on the fractional Fourier transformation  

NASA Astrophysics Data System (ADS)

Seismic data may suffer from too severe noise contamination to carry out further processing and interpretation procedure. In the paper, a new scheme was proposed based on the fractional Fourier transform (FrFT) in time frequency domain to mitigate noise. The scheme consists of two steps. In the first step, the seismic signal is filtered with the ordinary Butterworth filter in the frequency domain. The residual noises after frequency filtering are with the same frequencies with the filtered seismic signals. In order to mitigate the residual noises further, the FrFT filter is applied in the second step. The results from the simulated seismic signals and the measurements data verify the validity of the proposed scheme in both frequency and time-frequency domains.

Zhai, Ming-Yue

2014-10-01

197

Gas emission analysis based on Fourier transformed infrared spectroscopy  

NASA Astrophysics Data System (ADS)

Solar occultation flux (SOF), a new optical technology to detect the gas based on the traditional Fourier transformed infrared spectroscopy (FTIR) developed quickly recently. In this paper, the system and the data analysis is investigated. First a multilayer transmission model of solar radiation is simulated. Then the retrieval process is illustrated. In the proceeding of the data analysis, the Levenberg-Marquardt non-linear square fitting is used to obtain the gas column concentration and the related emission ratio. After the theory certification, the built up system is conducted in a fertilizer plant in Hefei city .The results show SOF is available in the practice and the retrieved gas column concentration can give important information about the pollution emission and dispersion

Shu, Xiaowen; Zhang, Xiaofu; Lian, Xu; Jin, Hui

2014-12-01

198

Multiple images encryption based on Fourier transform hologram  

NASA Astrophysics Data System (ADS)

A new optical encryption method is proposed in this paper to achieve multiple images encryption. We introduce reference waves with different incident angles and random amplitude masks into a Fourier transform hologram configuration to encrypt multiple images. In the encryption procedure, different random amplitude masks (RAMs) which are placed into the reference arm vertically admit the multiplexing capability. When decrypting one of the original images, reference wave with the same incident angle as encrypting the target image is used to illuminate the encrypted hologram with the insertion of random amplitude mask whose transmissivity is reciprocal of that of the encrypting random amplitude mask in the reference arm. We also simulate and analyze the influence of partly wrong decrypting key on the decrypted results. Numerical simulation proves that the proposed encryption method is valid and of high security level.

Lin, Chao; Shen, Xueju; Tang, Rui; Zou, Xiao

2012-03-01

199

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

200

Quark-antiquark static energy from a restricted Fourier transform  

E-print Network

We provide a fully analytical determination of the perturbative quark-antiquark static energy in position space as defined by a restricted Fourier transformation from momentum to position space. Such a determination is complicated by the fact that the static energy genuinely decomposes into a strictly perturbative part (made up of contributions $\\sim\\alpha_s^n$, with $n\\in\\mathbb{N}$) which is conventionally evaluated in momentum space, and a so-called ultrasoft part (including terms $\\sim\\alpha_s^{n+m}\\ln^m\\alpha_s$, with $n\\geq3$ and $m\\in\\mathbb{N}$) which, conversely, is naturally evaluated in position space. Our approach facilitates the explicit determination of the static energy in position space at the accuracy with which the perturbative potential in momentum space is known, i.e., presently up to order $\\alpha_s^4$.

Felix Karbstein

2014-04-23

201

Structural Characterization of Carbohydrates by Fourier Transform Tandem Mass Spectrometry  

PubMed Central

Fourier transform tandem mass spectrometry (MS/MS) provides high mass accuracy, high sensitivity, and analytical versatility and has therefore emerged as an indispensable tool for structural elucidation of biomolecules. Glycosylation is one of the most common posttranslational modifications, occurring in ~50% of proteins. However, due to the structural diversity of carbohydrates, arising from non-template driven biosynthesis, achievement of detailed structural insight is highly challenging. This review briefly discusses carbohydrate sample preparation and ionization methods, and highlights recent developments in alternative high-resolution MS/MS strategies, including infrared multiphoton dissociation (IRMPD), electron capture dissociation (ECD), and electron detachment dissociation (EDD), for carbohydrates with a focus on glycans and proteoglycans from mammalian glycoproteins. PMID:22389641

Zhou, Wen; Håkansson, Kristina

2012-01-01

202

Nonlinear effects of phase blurring on Fourier transform holograms  

SciTech Connect

Liquid-crystal light valves can have intensity-dependent resolution. We find for a nematic liquid-crystal light valve that this effect is well modeled as a phase that has been blurred by a linear space-invariant filter. The phase point-spread function is measured and is used in simulations to demonstrate that it introduces intermodulation products to the diffraction patterns of computer-generated Fourier transform holograms. Also, the influence of phase blurring on a pseudorandom-encoding algorithm is evaluated in closed form. This analysis applied to a spot array generator design indicates that nonlinear effects are negligible only if the diameter of the point-spread function is a small fraction of the pixel spacing. (c) 2000 Optical Society of America.

Duelli, Markus [The ElectroOptics Research Institute, University of Louisville, Louisville, Kentucky 40292 (United States); Ge, Li [The ElectroOptics Research Institute, University of Louisville, Louisville, Kentucky 40292 (United States); Cohn, Robert W. [The ElectroOptics Research Institute, University of Louisville, Louisville, Kentucky 40292 (United States)

2000-09-01

203

Vector power multiple-parameter fractional Fourier transform of image encryption algorithm  

NASA Astrophysics Data System (ADS)

In this paper, we propose a multiple-parameter fractional Fourier transform with its transform order being a real vector, based on which a high-security image encryption scheme is also given. This novel fractional Fourier transform has removed the restriction on the dimension of transform order and highly enhances the security of image encryption scheme proposed in this paper without increasing the computational complexity and hardware cost. The numerical results verify the efficacy and security of this image encryption method. The vector power multi-parameter fractional Fourier transform is a generalized form of the classical fractional Fourier transform with all the previous fractional Fourier transform as its special cases and has theoretical significance in information processing and information security.

Ran, Qiwen; Zhao, Tieyu; Yuan, Lin; Wang, Jian; Xu, Lei

2014-11-01

204

Quantization maps, algebra representation, and non-commutative Fourier transform for Lie groups  

SciTech Connect

The phase space given by the cotangent bundle of a Lie group appears in the context of several models for physical systems. A representation for the quantum system in terms of non-commutative functions on the (dual) Lie algebra, and a generalized notion of (non-commutative) Fourier transform, different from standard harmonic analysis, has been recently developed, and found several applications, especially in the quantum gravity literature. We show that this algebra representation can be defined on the sole basis of a quantization map of the classical Poisson algebra, and identify the conditions for its existence. In particular, the corresponding non-commutative star-product carried by this representation is obtained directly from the quantization map via deformation quantization. We then clarify under which conditions a unitary intertwiner between such algebra representation and the usual group representation can be constructed giving rise to the non-commutative plane waves and consequently, the non-commutative Fourier transform. The compact groups U(1) and SU(2) are considered for different choices of quantization maps, such as the symmetric and the Duflo map, and we exhibit the corresponding star-products, algebra representations, and non-commutative plane waves.

Guedes, Carlos; Oriti, Daniele [Max Planck Institute for Gravitational Physics (Albert Einstein Institute), Am Mühlenberg 1, 14476 Potsdam (Germany)] [Max Planck Institute for Gravitational Physics (Albert Einstein Institute), Am Mühlenberg 1, 14476 Potsdam (Germany); Raasakka, Matti [Max Planck Institute for Gravitational Physics (Albert Einstein Institute), Am Mühlenberg 1, 14476 Potsdam (Germany) [Max Planck Institute for Gravitational Physics (Albert Einstein Institute), Am Mühlenberg 1, 14476 Potsdam (Germany); LIPN, Institut Galilée, Université Paris-Nord, 99, av. Clement, 93430 Villetaneuse (France)

2013-08-15

205

Pulsed Fourier-transform NQR of sup 14 N with a dc SQUID  

SciTech Connect

The zero-field free induction decay of solid ammonium perchlorate at 1.5 K has been directly detected with a dc superconducting quantum interference device. The Fourier-transform spectrum consists of three sharp lines at 17.4, 38.8, and 56.2 kHz arising from pure {sup 14}N nuclear quadrupole resonance transitions. The absence of splittings and resonance transitions from dipolar-coupled proton spins is attributed to reorientation of the ammonium groups by quantum tunneling in combination with motional averaging in the three proton levels characterized by the irreducible representation {ital T}. The measured {sup 14}N spin-spin relaxation time is 22{plus minus}2 ms and the spin-lattice relaxation time is 63{plus minus}6 ms.

Huerlimann, M.D.; Pennington, C.H.; Fan, N.Q.; Clarke, J.; Pines, A.; Hahn, E.L. (Department of Physics, University of California, Berkeley, Berkeley, California 94720 (United States) Department of Chemistry, University of California, Berkeley, Berkeley, California 94720 (United States) Materials Sciences Division, Lawrence Berkeley Laboratory, Berkeley, California 94720 (United States))

1992-07-27

206

The Fourier-Like and Hartley-Like Wavelet Analysis Based on Hilbert Transforms  

E-print Network

In continuous-time wavelet analysis, most wavelet present some kind of symmetry. Based on the Fourier and Hartley transform kernels, a new wavelet multiresolution analysis is proposed. This approach is based on a pair of orthogonal wavelet functions and is named as the Fourier-Like and Hartley-Like wavelet analysis. A Hilbert transform analysis on the wavelet theory is also included.

Soares, L R; Cintra, R J

2015-01-01

207

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

E-print Network

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

Naylor, David A.

208

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

Microsoft Academic Search

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

Ferdinand Klaus; Ute Blewonska; Bernhard O. Bundschuh

1994-01-01

209

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

E-print Network

] demonstrated this technique with a two-aperture telescope and a scene of point sources. However, the spatialReconstruction of multispectral image cubes from multiple- telescope array Fourier transform@optics.rochester.edu Abstract: Multiple-telescope arrays can function as Fourier transform imaging spectrometers, using

Fienup, James R.

210

Physical transformations between quantum states  

E-print Network

Given two sets of quantum states {A_1, ..., A_k} and {B_1, ..., B_k}, represented as sets of density matrices, necessary and sufficient conditions are obtained for the existence of a physical transformation T, represented as a trace-preserving completely positive map, such that T(A_i) = B_i for i = 1, ..., k. General completely positive maps without the trace-preserving requirement, and unital completely positive maps transforming the states are also considered.

Zejun Huang; Chi-Kwong Li; Edward Poon; Nung-Sing Sze

2012-10-26

211

A Fourier transform spectrometer using resonant vertical comb actuators  

NASA Astrophysics Data System (ADS)

The design, fabrication and characterization of a novel out-of-plane vertical comb-drive actuator based lamellar grating interferometer (LGI) is reported. The interferometer utilizes resonant mode vertical comb actuators, where comb fingers are simultaneously used for actuation and as a movable diffraction grating, making the device very compact. The Fourier transform of the zeroth order intensity pattern as a function of the optical path difference gives the spectrum of light. The main advantages offered by the proposed device are a long travel range (i.e. good spectral resolution), a large clear aperture (i.e. high light efficiency), and a very simple, robust and compact spectrometer structure. Peak-to-peak 106 µm out-of-plane deflection is observed in ambient pressure and at 28 V, corresponding to a theoretical spectral resolution of about 0.4 nm in the visible band and 3.6 nm at 1.5 µm. A simple CMOS compatible process based on bulk micromachining of a silicon-on-insulator wafer is used for the device fabrication.

Ataman, Caglar; Urey, Hakan; Wolter, Alexander

2006-12-01

212

Single beam Fourier transform digital holographic quantitative phase microscopy  

SciTech Connect

Quantitative phase contrast microscopy reveals thickness or height information of a biological or technical micro-object under investigation. The information obtained from this process provides a means to study their dynamics. Digital holographic (DH) microscopy is one of the most used, state of the art single-shot quantitative techniques for three dimensional imaging of living cells. Conventional off axis DH microscopy directly provides phase contrast images of the objects. However, this process requires two separate beams and their ratio adjustment for high contrast interference fringes. Also the use of two separate beams may make the system more vulnerable to vibrations. Single beam techniques can overcome these hurdles while remaining compact as well. Here, we describe the development of a single beam DH microscope providing whole field imaging of micro-objects. A hologram of the magnified object projected on to a diffuser co-located with a pinhole is recorded with the use of a commercially available diode laser and an arrayed sensor. A Fourier transform of the recorded hologram directly yields the complex amplitude at the image plane. The method proposed was investigated using various phase objects. It was also used to image the dynamics of human red blood cells in which sub-micrometer level thickness variation were measurable.

Anand, A., E-mail: arun-nair-in@yahoo.com; Chhaniwal, V. K.; Mahajan, S.; Trivedi, V. [Optics Laboratory, Applied Physics Department, Faculty of Technology and Engineering, M.S. University of Baroda, Vadodara 390001 (India)] [Optics Laboratory, Applied Physics Department, Faculty of Technology and Engineering, M.S. University of Baroda, Vadodara 390001 (India); Faridian, A.; Pedrini, G.; Osten, W. [Institut für Technische Optik, Universität Stuttgart, Pfaffenwaldring 9, 70569 Stuttgart (Germany)] [Institut für Technische Optik, Universität Stuttgart, Pfaffenwaldring 9, 70569 Stuttgart (Germany); Dubey, S. K. [Siemens Technology and Services Pvt. Ltd, Corporate Technology—Research and Technology Centre, Bangalore 560100 (India)] [Siemens Technology and Services Pvt. Ltd, Corporate Technology—Research and Technology Centre, Bangalore 560100 (India); Javidi, B. [Department of Electrical and Computer Engineering, U-4157, University of Connecticut, Storrs, Connecticut 06269-2157 (United States)] [Department of Electrical and Computer Engineering, U-4157, University of Connecticut, Storrs, Connecticut 06269-2157 (United States)

2014-03-10

213

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

2007-02-01

214

Geosynchronous Imaging Fourier Transform Spectrometer (GIFTS): Imaging and Tracking Capability  

NASA Technical Reports Server (NTRS)

The geosynchronous-imaging Fourier transform spectrometer (GIFTS) engineering demonstration unit (EDU) is an imaging infrared spectrometer designed for atmospheric soundings. It measures the infrared spectrum in two spectral bands (14.6 to 8.8 microns, 6.0 to 4.4 microns) using two 128 128 detector arrays with a spectral resolution of 0.57/cm with a scan duration of approx. 11 seconds. From a geosynchronous orbit, the instrument will have the capability of taking successive measurements of such data to scan desired regions of the globe, from which atmospheric status, cloud parameters, wind field profiles, and other derived products can be retrieved. The GIFTS EDU provides a flexible and accurate testbed for the new challenges of the emerging hyperspectral era. The EDU ground-based measurement experiment, held in Logan, Utah during September 2006, demonstrated its extensive capabilities and potential for geosynchronous and other applications (e.g., Earth observing environmental measurements). This paper addresses the experiment objectives and overall performance of the sensor system with a focus on the GIFTS EDU imaging capability and proof of the GIFTS measurement concept.

Zhou, D. K.; Larar, A. M.; Liu, Xu; Reisse, R. A.; Smith, W. L.; Revercomb, H. E.; Bingham, G. E.; Zollinger, L. J.; Tansock, J. J.; Huppi, Ronald J.

2007-01-01

215

Transmission fourier transform Raman spectroscopy of pharmaceutical tablet cores.  

PubMed

Transmission Fourier transform (FT) Raman spectroscopy of pharmaceutical tablet cores is demonstrated using traditional, unmodified commercial instrumentation. The benefits of improved precision over backscattering Raman spectroscopy due to increased sample volume are demonstrated. Self-absorption effects on analyte band ratios and sample probe volume are apparent, however. A survey of near-infrared (NIR) absorption spectra in the FT-Raman spectral range (approximately 0 to 3500 wavenumber shift from 1064 nm, or 1064 to 1700 nm) of molecules with a wide range of NIR-active functional groups shows that although absorption at the laser wavelength (1064 nm) is relatively small, some regions of the Raman spectrum coincide with NIR absorbances of 0.5 per cm or greater. Fortunately, the pharmaceutically important regions of the Raman shift spectrum from 0 to 600 cm(-1) and from 1400 to 1900 cm(-1) exhibit low self-absorption for most organic materials. A statistical analysis of transmission FT-Raman noise in spectra collected from different regions of a pharmaceutical tablet provides insight into both spectral distortion and reduced sampling volume caused by self-absorption. PMID:22449328

Pelletier, Michael J; Larkin, Peter; Santangelo, Matthew

2012-04-01

216

Ivory and simulated ivory artefacts: Fourier transform Raman diagnostic study  

NASA Astrophysics Data System (ADS)

The Fourier transform Raman spectrum of ivory is reported and assignments are proposed for the major spectroscopic features. Application of the FT Raman technique to the non-destructive diagnostic identification of ivory and simulated ivory artefacts is illustrated with reference to several specimens, both modern and aged. Although the FT Raman spectrum of ivory is similar to that of other bone samples, the characteristic vibrational modes are identified and it is suggested that the relative intensity ratio of the ?(CH) stretching bands near 2930 cm -1 and the hydroxyapatite ?(PO) stretching band at 960 cm -1 is a good diagnostic parameter for ivory. Other modes, such as ?(NH) near 3300 cm -1, the ?(CH 2) profile near 1250 cm -1 and ?(CC) symmetric ring stretching intensity at 1002 cm -1 are also good confirming indicators to distinguish ivory from bone and synthetic specimens. Modern specimens of "ivory" using synthetic polymers and polymer-inorganic composites are easily distinguished spectroscopically from genuine ivory, particularly close textural specimens, which involved a synthetic blending of poly(methylmethacrylate), polystyrene and calcite.

Edwards, H. G. M.; Farwell, D. W.

1995-11-01

217

Applications of Fourier transform-infrared spectroscopy to edible oils.  

PubMed

Recent developments in Fourier transform infrared (FT-IR) spectroscopy instrumentation extend the application of this technique to the field of food research, facilitating particularly the studies on edible oils and fats. In this work, FT-IR spectroscopy is used as an effective analytical tool in order: (a) to determine extra virgin olive oil adulteration with lower priced vegetable oils (sunflower oil, soyabean oil, sesame oil, corn oil) and (b) to monitor the oxidation process of corn oil samples undergone during heating or/and exposure to ultraviolet radiation. A band shift observed at 3009 cm(-1) assigned to the C_H stretching vibration of the cis-double bond, allows the determination of extra virgin olive oil adulteration. Changes in the 3050-2800 and 1745 cm(-1) spectral region appear after heating at elevated temperatures and aid the oxidation process monitoring. In addition, an analytical technique for the measurement of carbonylic compounds in oils, produced after heating, is applied. The possible antioxidant effect of oregano is also discussed. PMID:17723561

Vlachos, N; Skopelitis, Y; Psaroudaki, M; Konstantinidou, V; Chatzilazarou, A; Tegou, E

2006-07-28

218

[Study on spectrum inversion of spatially modulated Fourier transform spectrometer].  

PubMed

The sampling mode of static Fourier transform spectrometer is spatial domain sampling. The interferogram function is sampled by two orthogonal stepped mirrors and the interference irradiance is received by the detector. The interferogram image is a planar spatial array which consists of MXM interferogram units. After image segmentation, the interferogram image is divided into M x M interferogram units according to comparability criterion. By means of addressing location, the sampled interferogram sequence which matches up to the discrete optical path difference sequence could be gained. Using over-zero sampling technique, the big single side interferogram sequence and the small double side interferogram sequence are apodizated by different window functions. For the sake of correcting phase error, the frequency-domain spectrum correction and space-domain interferogram correction are researched and improved. The simulation result shows that the two methods can both gain the perfect spectrum line shape, and the effect of space-domain interferogram correction is better than others with the spectrum standard deviation only 0.012 088. PMID:22870669

Lü, Jin-Guang; Liang, Jing-Qiu; Liang, Zhong-Zhu

2012-06-01

219

Spectral analysis of cervical cells using the discrete Fourier transform.  

PubMed

This paper contains results from a preliminary study of spectral analysis techniques applied to the classification of cervical cells from routinely prepared Papanicolaou cervical smears. Experiments were conducted using a subset of 110 normals and 110 dyskaryotic single cell images randomly selected from a larger cell image data base. An assessment was made of the contribution of different regions within a cell image to the frequency spectrum. Three image sets were used, the original image itself plus two derived from it. In the first derived set, only nuclear size and shape were used. In the second set nuclear morphology and texture were included. Nuclear masking was performed using an interactive segmentation procedure. The discrete Fourier transform was applied to each image in the three image sets and classification experiments were performed using 80 features derived from the frequency spectra. An optimum set of features was selected for each experiment by canonical analysis. Good classification results were obtained when features extracted solely from nuclear shape were used. The inclusion of information relating to nuclear texture improved the results. However, inclusion of the extra nuclear region degraded the classifier's ability to discriminate between cell groups. PMID:8466852

Banda-Gamboa, H; Ricketts, I; Cairns, A; Hussein, K

1993-03-01

220

Ribosomal DNA Nanoprobes studied by Fourier Transform Infrared spectroscopy  

NASA Astrophysics Data System (ADS)

Paracoccidioides brasiliensis (P. brasiliensis) is a thermo-dimorphic fungus that causes paracoccidioidomycosis. Brazil epidemiological data shows that endemic areas are the subtropical regions, especially where agricultural activities predominate such as the Southeast, South, and Midwest. There are several tests to diagnose paracoccidioidomycosis, but they have many limitations such as low sensitivity, high cost, and a cross-reacting problem. In this work, gold nanoprobes were used to identify P. brasiliensis as an alternative diagnostic technique, which is easier to apply, costs less, and has great potential for application. The specific Ribosomal sequence of P. brasiliensis DNA was amplified and used to design the nanoprobes using a thiol-modified oligonucleotide. The results of positive and negative tests were done by UV-visible and Fourier Transform Infrared (FT-IR) measurements. The deconvolution of FT-IR sample spectra showed differences in the vibrational modes from the hydrogen bridge NHN and NHO bands that form the double helix DNA for samples matching the DNA sequence of nanoprobes that could be used to classify the samples.

Fagundes, Jaciara; Castilho, Maiara L.; Téllez Soto, Claudio A.; Vieira, Laís de Souza; Canevari, Renata A.; Fávero, Priscila P.; Martin, Airton A.; Raniero, Leandro

2014-01-01

221

Spectroscopic Stokes polarimetry based on Fourier transform spectrometer  

NASA Astrophysics Data System (ADS)

Two methods are proposed for measuring the spectroscopic Stokes parameters using a Fourier transform spectrometer. In the first method, it is designed for single point measurement. The parameters are extracted using an optical setup comprising a white light source, a polarizer set to 0°, a quarter-wave plate and a scanning Michelson interferometer. In the proposed approach, the parameters are extracted from the intensity distributions of the interferograms produced with the quarter-wave plate rotated to 0°, 22.5°, 45° and -45°, respectively. For the second approach, the full-field and dynamic measurement can be designed based upon the first method with special angle design in a polarizer and a quarter-wave plate. Hence, the interferograms of two-dimensional detection also can be simultaneously extracted via a pixelated phase-retarder and polarizer array on a high-speed CCD camera and a parallel read-out circuit with a multi-channel analog to digital converter. Thus, a full-field and dynamic spectroscopic Stokes polarimetry without any rotating components could be developed. The validity of the proposed methods is demonstrated both numerically and experimentally. To the authors' knowledge, this could be the simplest optical arrangement in extracting the spectral Stokes parameters. Importantly, the latter one method avoids the need for rotating components within the optical system and therefore provides an experimentally straightforward means of extracting the dynamic spectral Stokes parameters.

Liu, Yeng-Cheng; Lo, Yu-Lung; Li, Chang-Ye; Liao, Chia-Chi

2015-02-01

222

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

223

Picolinic and isonicotinic acids: a Fourier transform microwave spectroscopy study.  

PubMed

The rotational spectra of laser ablated picolinic and isonicotinic acids have been studied using broadband chirped pulse (CP-FTMW) and narrowband molecular beam (MB-FTMW) Fourier transform microwave spectroscopies. Two conformers of picolinic acid, s-cis-I and s-cis-II, and one conformer of isonicotinic acid have been identified through the analysis of their rotational spectra. The values of the inertial defect and the quadrupole coupling constants obtained for the most stable s-cis-I conformer of picolinic acid, evidence the formation of an O-H···N hydrogen bond between the acid group and the endocyclic N atom. The stabilization provided by this hydrogen bond compensates the destabilization energy due to the adoption of a -COOH trans configuration in this conformer. Its rs structure has been derived from the rotational spectra of several (13)C, (15)N, and (18)O species observed in their natural abundances. Mesomeric effects have been revealed by comparing the experimental values of the (14)N nuclear quadrupole coupling constants in the isomeric series of picolinic, isonicotinic, and nicotinic acids. PMID:25382020

Peña, Isabel; Varela, Marcelino; Franco, Vanina G; López, Juan C; Cabezas, Carlos; Alonso, José L

2014-12-01

224

Ribosomal DNA nanoprobes studied by Fourier transform infrared spectroscopy.  

PubMed

Paracoccidioides brasiliensis (P. brasiliensis) is a thermo-dimorphic fungus that causes paracoccidioidomycosis. Brazil epidemiological data shows that endemic areas are the subtropical regions, especially where agricultural activities predominate such as the Southeast, South, and Midwest. There are several tests to diagnose paracoccidioidomycosis, but they have many limitations such as low sensitivity, high cost, and a cross-reacting problem. In this work, gold nanoprobes were used to identify P. brasiliensis as an alternative diagnostic technique, which is easier to apply, costs less, and has great potential for application. The specific Ribosomal sequence of P. brasiliensis DNA was amplified and used to design the nanoprobes using a thiol-modified oligonucleotide. The results of positive and negative tests were done by UV-visible and Fourier Transform Infrared (FT-IR) measurements. The deconvolution of FT-IR sample spectra showed differences in the vibrational modes from the hydrogen bridge NHN and NHO bands that form the double helix DNA for samples matching the DNA sequence of nanoprobes that could be used to classify the samples. PMID:24036304

Fagundes, Jaciara; Castilho, Maiara L; Téllez Soto, Claudio A; Vieira, Laís de Souza; Canevari, Renata A; Fávero, Priscila P; Martin, Airton A; Raniero, Leandro

2014-01-24

225

A direct digital synthesis chirped pulse Fourier transform microwave spectrometer.  

PubMed

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. PMID:24007050

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

2013-08-01

226

Identification of species of Brucella using Fourier transform infrared spectroscopy.  

PubMed

Fourier transform infrared spectroscopy (FTIR) is a technique that has been used over the years in chemical analysis for the identification of substances and is one that may be applied to the characterisation of microorganisms. The marked tendency of Brucella towards variation in the smooth rough phase, together with the laboriousness and risk involved in the methods used in their identification, make their classification difficult. We studied the type strains of the different species and biovars of Brucella and 11 isolates of human origin of Brucella melitensis, six corresponding to biovar 1, one to biovar 2 and five to biovar 3. The results of linear discriminant analysis performed using the data provide an above 95% likelihood of correct classification, over half of which are in fact above 99% for the vast majority of Brucella strains. Only one case of B. melitensis biovar 1 has been incorrectly classified. The rest of the microorganisms studied (Staphylococcus aureus, Strteptococcus pyogenes, Enterococcus faecalis, Corynebacterium pseudodiphtheriticum, Clostridium perfringens, Escherichia coli, Acinetobacter calcoaceticus and Pseudomonas aeruginosa) have been classified correctly in all cases to a likelihood of over 80%. In the graphic representation of the analysis, a grouping of these can be seen in clusters, which include the different species. One of these comprises B. melitensis, another Brucella abortus, and another wider one is made up of Brucella suis. The Brucella canis, Brucella ovis and Brucella neotomae strains appear separate from the previously described groups. PMID:14500003

Miguel Gómez, M A; Bratos Pérez, M A; Martín Gil, F J; Dueñas Díez, A; Martín Rodríguez, J F; Gutiérrez Rodríguez, P; Orduña Domingo, A; Rodríguez Torres, A

2003-10-01

227

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. PMID:21176143

2010-01-01

228

Fourier transform methods applied to an optical heterodyne profilometer  

NASA Astrophysics Data System (ADS)

In this work, theory and experiment describe the performance of a surface profile measurement device based on optical heterodyne interferometry are presented. The object and reference beams propagating through the interferometer are obtained by single-pass through an acousto-optic modulator. The diffraction orders 0 and the Doppler-shifted +1 (object and reference beams, respectively) are manipulated to propagate collinearly towards the interferometer output where a fast photodetector is placed to collect the irradiance. The modulated optical signal is Fourier transformed using a data acquisition card and RF communications software. The peak centered at the acousto-optic frequency in the power spectrum is filtered and averaged. The irregularities on the surface of the reflective sample are proportional to the height of this peak. The profile of a reflective blazed grating has been sketched by translating laterally the sample using a nanopositioning system. Experimental results are compared to the measurement done with a scanning electron microscope. There has been found a good agreement between both methods.

Beltrán-González, A.; García-Torales, G.; Martínez-Ponce, G.

2013-11-01

229

Continued Development of a Planetary Imaging Fourier Transform Spectrometer (PIFTS)  

NASA Technical Reports Server (NTRS)

This report describes continued efforts to evaluate a breadboard of a Planetary Imaging Fourier Transform Spectrometer (PIFTS). The PIFTS breadboard was developed under prior PIDDP funding. That effort is described in the final report for NASA Grant NAG5-6248 and in two conference papers (Sromovsky et al. 2000; Revercomb et al. 2000). The PIFTS breadboard was designed for near-IR (1-5.2 micrometer imaging of planetary targets with spectral resolving powers of several hundred to several thousand, using an InSb detector array providing at least 64x64 pixels imaging detail. The major focus of the development effort was to combine existing technologies to produce a small and low power design compatible with a very low mass flyable instrument. The objective of this grant (NAG5-10729) was further characterization of the breadboard performance, including intercomparisons with the highly accurate non-imaging Advanced Emitted Radiance Interferometer (AERI) (Revercomb et al. 1994; Best et al. 1997).

Sromovsky, L. A.

2002-01-01

230

Fourier transform optical profilometry using fiber optic Lloyd's mirrors.  

PubMed

A fiber optic Lloyd's mirror assembly is used to obtain various optical interference patterns for the detection of 3D rigid body shapes. Two types of fiber optic Lloyd's systems are used in this work. The first consists of a single-mode optical fiber and a highly reflecting flat mirror to produce bright and dark strips. The second is constructed by locating a single-mode optical fiber in a v-groove, which is formed by two orthogonal flat mirrors to allow the generation of square-type interference patterns for the desired applications. The structured light patterns formed by these two fiber Lloyd's techniques are projected onto 3D objects. Fringe patterns are deformed due to the object's surface topography, which are captured by a digital CCD camera and processed with a Fourier transform technique to accomplish 3D surface topography of the object. It is demonstrated that the fiber-optic Lloyd's technique proposed in this work is more compact, more stable, and easier to configure than other existing surface profilometry systems, since it does not include any high-cost optical tools such as aligners, couplers, or 3D stages. The fringe patterns are observed to be more robust against environmental disturbances such as ambient temperature and vibrations. PMID:25608057

Kart, Türkay; Köso?lu, Gül?en; Yüksel, Heba; ?nci, Mehmet Naci

2014-12-10

231

Single beam Fourier transform digital holographic quantitative phase microscopy  

NASA Astrophysics Data System (ADS)

Quantitative phase contrast microscopy reveals thickness or height information of a biological or technical micro-object under investigation. The information obtained from this process provides a means to study their dynamics. Digital holographic (DH) microscopy is one of the most used, state of the art single-shot quantitative techniques for three dimensional imaging of living cells. Conventional off axis DH microscopy directly provides phase contrast images of the objects. However, this process requires two separate beams and their ratio adjustment for high contrast interference fringes. Also the use of two separate beams may make the system more vulnerable to vibrations. Single beam techniques can overcome these hurdles while remaining compact as well. Here, we describe the development of a single beam DH microscope providing whole field imaging of micro-objects. A hologram of the magnified object projected on to a diffuser co-located with a pinhole is recorded with the use of a commercially available diode laser and an arrayed sensor. A Fourier transform of the recorded hologram directly yields the complex amplitude at the image plane. The method proposed was investigated using various phase objects. It was also used to image the dynamics of human red blood cells in which sub-micrometer level thickness variation were measurable.

Anand, A.; Faridian, A.; Chhaniwal, V. K.; Mahajan, S.; Trivedi, V.; Dubey, S. K.; Pedrini, G.; Osten, W.; Javidi, B.

2014-03-01

232

External Second Gate-Fourier Transform Ion Mobility Spectrometry.  

SciTech Connect

Ion mobility spectrometry (IMS) is recognized as one of the most sensitive and versatile techniques for the detection of trace levels of organic vapors. IMS is widely used for detecting contraband narcotics, explosives, toxic industrial compounds and chemical warfare agents. Increasing threat of terrorist attacks, the proliferation of narcotics, Chemical Weapons Convention treaty verification as well as humanitarian de-mining efforts has mandated that equal importance be placed on the analysis time as well as the quality of the analytical data. (1) IMS is unrivaled when both speed of response and sensitivity has to be considered. (2) With conventional (signal averaging) IMS systems the number of available ions contributing to the measured signal to less than 1%. Furthermore, the signal averaging process incorporates scan-to-scan variations decreasing resolution. With external second gate Fourier Transform ion mobility spectrometry (FT-IMS), the entrance gate frequency is variable and can be altered in conjunction with other data acquisition parameters to increase the spectral resolution. The FT-IMS entrance gate operates with a 50% duty cycle and so affords a 7 to 10-fold increase in sensitivity. Recent data on high explosives are presented to demonstrate the parametric optimization in sensitivity and resolution of our system.

Tarver, Edward E., III

2005-01-01

233

Liquid chromatography/Fourier transform IR spectrometry interface flow cell  

DOEpatents

A zero dead volume (ZDV) microbore high performance liquid chromatography (..mu.. HPLC)/Fourier transform infrared (FTIR) interface flow cell includes an IR transparent crystal having a small diameter bore therein through which a sample liquid is passed. The interface flow cell further includes a metal holder in combination with a pair of inner, compressible seals for directly coupling the thus configured spectrometric flow cell to the outlet of a ..mu.. HPLC column end fitting to minimize the transfer volume of the effluents exiting the ..mu.. HPLC column which exhibit excellent flow characteristics due to the essentially unencumbered, open-flow design. The IR beam passes transverse to the sample flow through the circular bore within the IR transparent crystal, which is preferably comprised of potassium bromide (KBr) or calcium fluoride (CaF/sub 2/), so as to minimize interference patterns and vignetting encountered in conventional parallel-plate IR cells. The long IR beam pathlength and lensing effect of the circular cross-section of the sample volume in combination with the refractive index differences between the solvent and the transparent crystal serve to focus the IR beam in enhancing sample detection sensitivity by an order of magnitude.

Johnson, C.C.; Taylor, L.T.

1985-01-04

234

Liquid chromatography/Fourier transform IR spectrometry interface flow cell  

DOEpatents

A zero dead volume (ZDV) microbore high performance liquid chromatography (.mu.HPLC)/Fourier transform infrared (FTIR) interface flow cell includes an IR transparent crystal having a small diameter bore therein through which a sample liquid is passed. The interface flow cell further includes a metal holder in combination with a pair of inner, compressible seals for directly coupling the thus configured spectrometric flow cell to the outlet of a .mu.HPLC column end fitting to minimize the transfer volume of the effluents exiting the .mu.HPLC column which exhibit excellent flow characteristics due to the essentially unencumbered, open-flow design. The IR beam passes transverse to the sample flow through the circular bore within the IR transparent crystal, which is preferably comprised of potassium bromide (KBr) or calcium fluoride (CaF.sub.2), so as to minimize interference patterns and vignetting encountered in conventional parallel-plate IR cells. The long IR beam pathlength and lensing effect of the circular cross-section of the sample volume in combination with the refractive index differences between the solvent and the transparent crystal serve to focus the IR beam in enhancing sample detection sensitivity by an order of magnitude.

Johnson, Charles C. (Fairfield, OH); Taylor, Larry T. (Blacksburg, VA)

1986-01-01

235

Optimal Padding for the Two-Dimensional Fast Fourier Transform  

NASA Technical Reports Server (NTRS)

One-dimensional Fast Fourier Transform (FFT) operations work fastest on grids whose size is divisible by a power of two. Because of this, padding grids (that are not already sized to a power of two) so that their size is the next highest power of two can speed up operations. While this works well for one-dimensional grids, it does not work well for two-dimensional grids. For a two-dimensional grid, there are certain pad sizes that work better than others. Therefore, the need exists to generalize a strategy for determining optimal pad sizes. There are three steps in the FFT algorithm. The first is to perform a one-dimensional transform on each row in the grid. The second step is to transpose the resulting matrix. The third step is to perform a one-dimensional transform on each row in the resulting grid. Steps one and three both benefit from padding the row to the next highest power of two, but the second step needs a novel approach. An algorithm was developed that struck a balance between optimizing the grid pad size with prime factors that are small (which are optimal for one-dimensional operations), and with prime factors that are large (which are optimal for two-dimensional operations). This algorithm optimizes based on average run times, and is not fine-tuned for any specific application. It increases the amount of times that processor-requested data is found in the set-associative processor cache. Cache retrievals are 4-10 times faster than conventional memory retrievals. The tested implementation of the algorithm resulted in faster execution times on all platforms tested, but with varying sized grids. This is because various computer architectures process commands differently. The test grid was 512 512. Using a 540 540 grid on a Pentium V processor, the code ran 30 percent faster. On a PowerPC, a 256x256 grid worked best. A Core2Duo computer preferred either a 1040x1040 (15 percent faster) or a 1008x1008 (30 percent faster) grid. There are many industries that can benefit from this algorithm, including optics, image-processing, signal-processing, and engineering applications.

Dean, Bruce H.; Aronstein, David L.; Smith, Jeffrey S.

2011-01-01

236

Analyzing Real Vector Fields with Clifford Convolution and Clifford-Fourier Transform  

NASA Astrophysics Data System (ADS)

Postprocessing in computational fluid dynamics and processing of fluid flow measurements need robust methods that can deal with scalar and vector fields. While image processing of scalar data is a well-established discipline, there is a lack of similar methods for vector data. This paper surveys a particular approach defining convolution operators on vector fields using geometric algebra. This includes a corresponding Clifford-Fourier transform including a convolution theorem. Finally, a comparison is tried with related approaches for a Fourier transform of spatial vector or multivector data. In particular, we analyze the Fourier series based on quaternion holomorphic functions of Gürlebeck et al. (Funktionentheorie in der Ebene und im Raum, Birkhäuser, Basel, 2006), the quaternion Fourier transform of Hitzer (Proceedings of Function Theories in Higher Dimensions, 2006) and the biquaternion Fourier transform of Sangwine et al. (IEEE Trans. Signal Process. 56(4),1522-1531, 2007).

Reich, Wieland; Scheuermann, Gerik

237

Far-field radiation patterns of aperture antennas by the Winograd Fourier transform algorithm  

NASA Technical Reports Server (NTRS)

A more time-efficient algorithm for computing the discrete Fourier transform, the Winograd Fourier transform (WFT), is described. The WFT algorithm is compared with other transform algorithms. Results indicate that the WFT algorithm in antenna analysis appears to be a very successful application. Significant savings in cpu time will improve the computer turn around time and circumvent the need to resort to weekend runs.

Heisler, R.

1978-01-01

238

A combined ab initio, Fourier transform microwave and Fourier transform infrared spectroscopic investigation of ?-propiolactone: The ?8 and ?12 bands  

NASA Astrophysics Data System (ADS)

The pure rotational spectrum of ?-propiolactone (c-C 2H 4COO) has been recorded between 7 and 21 GHz using a pulsed jet Fourier transform microwave spectrometer. The resulting ground state spectroscopic constants guided the analysis of the rotationally-resolved infrared spectra of two bands that were collected using the far infrared beamline at the Canadian Light Source synchrotron. The observed modes correspond to motions best described as ring deformation ( ?12) at 747.2 cm -1 and CO ring stretching ( ?8) at 1095.4 cm -1. A global fit of 4430 a- and b-type transitions from the microwave spectrum and the two infrared bands provided an accurate set of ground state and excited state spectroscopic parameters. To complement the experimental results, the harmonic and anharmonic vibrational frequencies of all 21 infrared active modes of ?-propiolactone have been calculated using the DFT B3LYP method (6-311+G(d,p), 6-311++G(2d,3p) basis sets).

Chen, Ziqiu; van Wijngaarden, Jennifer

2009-10-01

239

Causal Correlation Functions and Fourier Transforms: Application in Calculating Pressure Induced Shifts  

NASA Technical Reports Server (NTRS)

By adopting a concept from signal processing, instead of starting from the correlation functions which are even, one considers the causal correlation functions whose Fourier transforms become complex. Their real and imaginary parts multiplied by 2 are the Fourier transforms of the original correlations and the subsequent Hilbert transforms, respectively. Thus, by taking this step one can complete the two previously needed transforms. However, to obviate performing the Cauchy principal integrations required in the Hilbert transforms is the greatest advantage. Meanwhile, because the causal correlations are well-bounded within the time domain and band limited in the frequency domain, one can replace their Fourier transforms by the discrete Fourier transforms and the latter can be carried out with the FFT algorithm. This replacement is justified by sampling theory because the Fourier transforms can be derived from the discrete Fourier transforms with the Nyquis rate without any distortions. We apply this method in calculating pressure induced shifts of H2O lines and obtain more reliable values. By comparing the calculated shifts with those in HITRAN 2008 and by screening both of them with the pair identity and the smooth variation rules, one can conclude many of shift values in HITRAN are not correct.

Ma, Q.; Tipping, R. H.; Lavrentieva, N. N.

2012-01-01

240

Observing extended sources with the Herschel SPIRE Fourier Transform Spectrometer  

NASA Astrophysics Data System (ADS)

The Spectral and Photometric Imaging Receiver (SPIRE) on the European Space Agency's Herschel Space Observatory utilizes a pioneering design for its imaging spectrometer in the form of a Fourier Transform Spectrometer (FTS). The standard FTS data reduction and calibration schemes are aimed at objects with either a spatial extent that is much larger than the beam size or a source that can be approximated as a point source within the beam. However, when sources are of intermediate spatial extent, neither of these calibrations schemes is appropriate and both the spatial response of the instrument and the source's light profile must be taken into account and the coupling between them explicitly derived. To that end, we derive the necessary corrections using an observed spectrum of a fully extended source with the beam profile and considering the source's light profile. We apply the derived correction to several observations of planets and compare the corrected spectra with their spectral models to study the beam coupling efficiency of the instrument in the case of partially extended sources. We find that we can apply these correction factors for sources with angular sizes up to ?D ~ 17''. We demonstrate how the angular size of an extended source can be estimated using the difference between the subspectra observed at the overlap bandwidth of the two frequency channels in the spectrometer, at 959 < ? < 989 GHz. Using this technique on an observation of Saturn, we estimate a size of 17.2'', which is 3% larger than its true size on the day of observation. Finally, we show the results of the correction applied on observations of a nearby galaxy, M82, and the compact core of a Galactic molecular cloud, Sgr B2.

Wu, R.; Polehampton, E. T.; Etxaluze, M.; Makiwa, G.; Naylor, D. A.; Salji, C.; Swinyard, B. M.; Ferlet, M.; van der Wiel, M. H. D.; Smith, A. J.; Fulton, T.; Griffin, M. J.; Baluteau, J.-P.; Benielli, D.; Glenn, J.; Hopwood, R.; Imhof, P.; Lim, T.; Lu, N.; Panuzzo, P.; Pearson, C.; Sidher, S.; Valtchanov, I.

2013-08-01

241

Tandem Fourier transform mass spectrometry of large molecules  

SciTech Connect

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 MS{sup n}). Here, new methods for soft ionization including {sup 252}Cf plasma desorption, 193 nm laser desorption, multiphoton ionization, and electrospray ionization (ESI) are demonstrated to produce abundant molecular ion species from a variety of compounds; ESI spectra of peptides as large as carbonic anhydrase (29,000 Da) with as many as 33+ charges are shown. Sensitivity can be improved up to 100x by remeasuring high mass ions multiple times; after excitation to a larger orbit for detection, energy lost through collisions with background neutrals returns these ions to the center of the cell where they are available for detection or dissociation in subsequent measurements. Photodissociation with 193 nm deposits 6.4 eV per photon absorbed, and produces spectra with extensive sequence information for a variety of peptides with dissociation efficiencies approaching 100%. Surface induced dissociation is demonstrated to produce structurally-useful fragmentation for peptides up to m/z 3100, a mass range where collisionally activated dissociation provides little information. Sensitivity for MS/MS and MS{sup n} measurements is substantially improved by simultaneously recording MS-II spectra of scores of precursors using the Hadamard deconvolution approach. Results with an eleven component mixture demonstrate a signal-to-noise (S/N) gain of 1.8x, as predicted by theory. A Hadamard of differences method is proposed in which all precursors are simultaneously dissociated such that posed in which all precursors are simultaneously dissociated such that MS{sup n} spectra of each of these could be obtained without additional time or sample over measuring just one (with the same S/N) individually.

Williams, E.R.

1990-01-01

242

High-resolution MALDI Fourier transform mass spectrometry of oligonucleotides.  

PubMed

The matrix-assisted laser desorption/ionization (MALDI) method has been used with an external ion source Fourier transform mass spectrometer (FIMS) to analyze single-stranded, mixed-base oligomers of DNA. It is demonstrated that ultrahigh mass resolution (830 000 fwhm) can be achieved for small oligomers, and high resolution (136 000 fwhm) can be achieved for a 25-mer at m/z 7634. MALDI-FTMS can clearly separate the molecular ion peaks from analyte-matrix adduct peaks and alkali metal-containing species that result from replacement of hydrogen ions with sodium or potassium ions at multiple sites along the phosphate backbone. Previous MALDI-FTMS studies of oligonucleotides had two limitations: (1) low sensitivity due to difficulty in trapping the high kinetic energy ions made by the laser and (2) fragmentation of the ions due to the long delay (tens to hundreds of milliseconds) between their formation and detection. Both of these problems are alleviated in the present study. With the external ion source FTMS instrument, ions made by MALDI are injected at low energy into the analyzer cell by a rf-only quadrupole ion guide, captured by gating the voltage on the trapping plates, and cooled by a 0.5-s pulse of argon gas. Under these conditions, fragmentation is minimized, and DNA ions can be trapped in the FTMS analyzer cell for greater than 50 s. Sensitivity is also improved, as demonstrated by detection of 1 pmol of a single-stranded, mixed-base 20-mer of DNA, with a signal-to-noise ratio greater than 20:1. PMID:9027224

Li, Y; Tang, K; Little, D P; Köster, H; Hunter, R L; McIver, R T

1996-07-01

243

Calibration of the Herschel SPIRE Fourier Transform Spectrometer  

NASA Astrophysics Data System (ADS)

The Herschel Spectral and Photometric REceiver (SPIRE) instrument consists of an imaging photometric camera and an imaging Fourier Transform Spectrometer (FTS), both operating over a frequency range of ˜450-1550 GHz. In this paper, we briefly review the FTS design, operation, and data reduction, and describe in detail the approach taken to relative calibration (removal of instrument signatures) and absolute calibration against standard astronomical sources. The calibration scheme assumes a spatially extended source and uses the Herschel telescope as primary calibrator. Conversion from extended to point-source calibration is carried out using observations of the planet Uranus. The model of the telescope emission is shown to be accurate to within 6 per cent and repeatable to better than 0.06 per cent and, by comparison with models of Mars and Neptune, the Uranus model is shown to be accurate to within 3 per cent. Multiple observations of a number of point-like sources show that the repeatability of the calibration is better than 1 per cent, if the effects of the satellite absolute pointing error (APE) are corrected. The satellite APE leads to a decrement in the derived flux, which can be up to ˜10 per cent (1 ?) at the high-frequency end of the SPIRE range in the first part of the mission, and ˜4 per cent after Herschel operational day 1011. The lower frequency range of the SPIRE band is unaffected by this pointing error due to the larger beam size. Overall, for well-pointed, point-like sources, the absolute flux calibration is better than 6 per cent, and for extended sources where mapping is required it is better than 7 per cent.

Swinyard, B. M.; Polehampton, E. T.; Hopwood, R.; Valtchanov, I.; Lu, N.; Fulton, T.; Benielli, D.; Imhof, P.; Marchili, N.; Baluteau, J.-P.; Bendo, G. J.; Ferlet, M.; Griffin, M. J.; Lim, T. L.; Makiwa, G.; Naylor, D. A.; Orton, G. S.; Papageorgiou, A.; Pearson, C. P.; Schulz, B.; Sidher, S. D.; Spencer, L. D.; van der Wiel, M. H. D.; Wu, R.

2014-06-01

244

Libyan Desert Glass: New field and Fourier transform infrared data  

NASA Astrophysics Data System (ADS)

Results are presented of new geological observations and laboratory analyses on Libyan Desert Glass (LDG), a unique kind of impact glass found in Egypt, probably 28.5-29.4 million years in age. A new LDG occurrence has been discovered some 50 km southward of the main LDG occurrences in the Great Sand Sea. From Fourier transform infrared (FTIR) analysis, the molecular structure of LDG is refined and significant differences are shown between LDG specimens and other pure silica glasses (fulgurite, industrial fused quartz, and amorphous biogenic silica) that are related to differences in their structures. The slight variations observed here for the mean Si-O-Si angle between the different glasses are attributed to their thermal histories. With regard to the other glasses analyzed, the LDG infrared spectral parameters point to a higher ratio of discontinuities and defects in the tetrahedral (SiO4) network. The quantitative mineralogical constitutions of sandstones and quartzites from the LDG geological setting were analyzed by FTIR. Cretaceous sandstones have a specific composition (about 90 wt% quartz, 10% dickite), clearly different from the Paleozoic ones (about 90 wt% quartz, but ?7% kaolinite). It is shown that the reddish silts bearing the LDG are constituted mainly of microquartz enriched with dickite, whose particle size distribution is characteristic of fluvio-lacustrine deposits, probably Oligocene to Miocene in age. The target rocks, most probably quartz sand, resulted from the weathering (loss of the cementing microquartz) of the Cretaceous sandstones from the Gilf Khebir Plateau with deposition in a high-energy environment.

Fröhlich, F.; Poupeau, G.; Badou, A.; Le Bourdonnec, F. X.; Sacquin, Y.; Dubernet, S.; Bardintzeff, J. M.; Véran, M.; Smith, D. C.; Diemer, E.

2013-12-01

245

A Synthetic Quadrature Phase Detector/Demodulator for Fourier Transform Transform Spectrometers  

NASA Technical Reports Server (NTRS)

A method is developed to demodulate (velocity correct) Fourier transform spectrometer (FTS) data that is taken with an analog to digital converter that digitizes equally spaced in time. This method makes it possible to use simple low cost, high resolution audio digitizers to record high quality data without the need for an event timer or quadrature laser hardware, and makes it possible to use a metrology laser of any wavelength. The reduced parts count and simplicity implementation makes it an attractive alternative in space based applications when compared to previous methods such as the Brault algorithm.

Campbell, Joel

2008-01-01

246

Fourier synthesis of optical potentials for atomic quantum gases  

SciTech Connect

We demonstrate a scheme for the Fourier synthesis of periodic optical potentials with asymmetric unit cells for atoms. In a proof of principle experiment, an atomic Bose-Einstein condensate is exposed to either symmetric or sawtooth-like asymmetric potentials by superimposing a conventional standing wave potential of {lambda}/2 spatial periodicity with a fourth-order lattice potential of {lambda}/4 periodicity. The high periodicity lattice is realized using dispersive properties of multiphoton Raman transitions. Future applications of the demonstrated scheme could range from the search for novel quantum phases in unconventionally shaped lattice potentials up to dissipationless atomic quantum ratchets.

Ritt, Gunnar; Geckeler, Carsten; Cennini, Giovanni [Physikalisches Institut der Universitaet Tuebingen, Auf der Morgenstelle 14, 72076 Tuebingen (Germany); Salger, Tobias; Weitz, Martin [Physikalisches Institut der Universitaet Tuebingen, Auf der Morgenstelle 14, 72076 Tuebingen (Germany); Institut fuer Angewandte Physik der Universitaet Bonn, Wegelerstrasse 8, 53115 Bonn (Germany)

2006-12-15

247

Clifford Fourier Transformation and Uncertainty Principle for the Clifford Geometric Algebra Cl 3,0  

Microsoft Academic Search

.  First, the basic concept of the vector derivative in geometric algebra is introduced. Second, beginning with the Fourier transform\\u000a on a scalar function we generalize to a real Fourier transform on Clifford multivector-valued functions\\u000a \\u000a $$ (f:\\\\user2{\\\\mathbb{R}}^3 \\\\to Cl_{3,0} ). $$\\u000a Third, we show a set of important properties of the Clifford Fourier transform on Cl3,0 such as differentiation properties, and

Bahri Mawardi

2006-01-01

248

Generalized Fourier transform and its application to the volume integral equation for elastic wave propagation in a half space  

Microsoft Academic Search

In the present study, a generalized Fourier transform for time harmonic elastic wave propagation in a half space is developed. The generalized Fourier transform is obtained from the spectral representation of the operator derived from the elastic wave equation. By means of the generalized Fourier transform, a volume integral equation method for the analysis of scattered elastic waves is presented.

Terumi Touhei

2009-01-01

249

Complexation of chitosan with acetic acid according to Fourier transform Raman spectroscopy data  

NASA Astrophysics Data System (ADS)

The results of the interaction between the protonated chitosan (CHI) macromolecule and the acetate ion in dilute acetic acid solutions were studied by Fourier transform Raman spectroscopy and quantum-chemical modeling. The complexation of CHI with the acetate ion showed itself as the 934 cm-1 band in the Raman spectrum, which suggests the formation of [CHI+ · CH3COO-] type ion pairs. It was concluded that a comparative analysis of the integrated intensities of the Raman bands in the range 880-940 cm-1 makes it possible to judge about the relative content of hydrated acetate ions, CHI macromolecules of the [CHI+ · CH3COO-] complex, and acetic acid molecules not involved in CHI protonation.

Mikhailov, G. P.; Tuchkov, S. V.; Lazarev, V. V.; Kulish, E. I.

2014-06-01

250

Complex signal recovery from two fractional Fourier transform intensities: order and noise dependence  

E-print Network

Complex signal recovery from two fractional Fourier transform intensities: order and noise on the fractional transform order are investigated. It is observed that in general, better results are obtained when the fractional transform order is close to unity and poorer results are obtained when the order is close to zero

Barshan, Billur

251

The Radon Transform on SO(3): A Fourier Slice Theorem and  

E-print Network

The Radon Transform on SO(3): A Fourier Slice Theorem and Numerical Inversion R. Hielscher 1 , D: Ralf.Hielscher@gsf.de The inversion of the one--dimensional Radon transform on the rotation group SO(3. This communication presents a novel approach to the numerical inversion of the one--dimensional Radon transform on SO

Potts, Daniel

252

The Radon Transform on SO(3): A Fourier Slice Theorem and  

E-print Network

The Radon Transform on SO(3): A Fourier Slice Theorem and Numerical Inversion R. Hielscher1 , D: Ralf.Hielscher@gsf.de The inversion of the one­dimensional Radon transform on the rotation group SO(3. This communication presents a novel approach to the numerical inversion of the one­dimensional Radon transform on SO

Potts, Daniel

253

Optimal warping function design for discrete time-warped Fourier transforms  

Microsoft Academic Search

We have recently introduced the class of generalized scale transforms and its subclass of warped Fourier transforms. Members in each class are defined by continuous time warping functions. While the two transforms admit a mathematically elegant analysis of warp-shift invariant systems it is still unclear how to design warping functions that deliver optimal representations for a given class of signals

Robert M. Nickel; William J. Williams

2000-01-01

254

Split manageable efficient algorithm for Fourier and Hadamard transforms  

Microsoft Academic Search

In this paper, a general, efficient, manageable split algorithm to compute one-dimensional (1-D) unitary transforms, by using the special partitioning in the frequency domain, is introduced. The partitions determine fast transformations that split the N-point unitary transform into a set of Ni-point transforms i=1: n(N1+...N n=N). Here, we introduce a class of splitting transformations: the so-called paired transforms. Based on

Artyom M. Grigoryan; Sos S. Agaian

2000-01-01

255

Rapidly scanning, high resolution Yb fiber based frequency comb-Fourier transform spectrometer  

Microsoft Academic Search

Frequency comb technology has revolutionized many aspects of spectroscopic measurements, most recently exemplified by the introduction of multi-heterodyne spectroscopy, which is now replacing traditional mechanically scanning Fourier transform spectrographs, providing orders of magnitude improvements in scan rate and resolution. However, a power scalable and compact, optically integratable platform for multi- heterodyne spectroscopy is still missing. This paper demonstrates a Fourier

A. Ruehl; I. Hartl; M. E. Fermann

2009-01-01

256

Momentum-space Lippmann-Schwinger-Equation, Fourier-transform with Gauss-Expansion-Method  

E-print Network

In these notes we construct the momentum-space potentials from configuration-space using for the Fourier-transformation the Gaussian-Expansion-Method (GEM). This has the advantage that the Fourier-Bessel integrals can be performed analytically, avoiding possible problems with the oscillations in the Bessel functions for large r, in particular for $p_f \

Th. A. Rijken

2014-09-19

257

CHARACTERIZING MODERN AND FOSSIL GYMNOSPERM EXUDATES USING MICRO-FOURIER TRANSFORM INFRARED SPECTROSCOPY  

E-print Network

CHARACTERIZING MODERN AND FOSSIL GYMNOSPERM EXUDATES USING MICRO-FOURIER TRANSFORM INFRARED spectroscopy have direct implications for the assessment of the fossil potential and the chemotaxonomic interpretation of modern and fossil gymnosperm exudates. Keywords: chemotaxonomy, plant resin, gum, conifers

Wolfe, Alexander P.

258

SPECIATION OF HAZARDOUS INORGANIC COMPOUNDS BY FOURIER TRANSFORM INFRARED (FTIR) SPECTROSCOPY  

EPA Science Inventory

The report describes an extension of the application of infrared methodology to characterize hazardous inorganic compounds in solid inorganic emissions, based on recent advances in instrumentation for Fourier transform infrared (FTIR) spectroscopy. The improved instrumentation, c...

259

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

260

Fourier Transform Infrared Spectroscopy: Part II. Advantages of FT-IR.  

ERIC Educational Resources Information Center

This is Part II in a series on Fourier transform infrared spectroscopy (FT-IR). Described are various advantages of FT-IR spectroscopy including energy advantages, wavenumber accuracy, constant resolution, polarization effects, and stepping at grating changes. (RH)

Perkins, W. D.

1987-01-01

261

Fourier transform of delayed fluorescence as an indicator of herbicide concentration.  

PubMed

It is well known that delayed fluorescence (DF) from Photosystem II (PSII) of plant leaves can be potentially used to sense herbicide pollution and evaluate the effect of herbicides on plant leaves. The research of using DF as a measure of herbicides in the literature was mainly conducted in time domain and qualitative correlation was often obtained. Fourier transform is often used to analyze signals. Viewing DF signal in frequency domain through Fourier transform may allow separation of signal components and provide a quantitative method for sensing herbicides. However, there is a lack of an attempt to use Fourier transform of DF as an indicator of herbicide. In this work, the relationship between the Fourier transform of DF and herbicide concentration was theoretically modelled and analyzed, which immediately yielded a quantitative method to measure herbicide concentration in frequency domain. Experiments were performed to validate the developed method. PMID:25152216

Guo, Ya; Tan, Jinglu

2014-12-21

262

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...

263

A High Resolution Fourier-Transform Spectrometer for the Measurement of Atmospheric Column Abundances  

NASA Technical Reports Server (NTRS)

A compact, high resolution Fourier-transform spectrometer for atmospheric near ultraviolet spectroscopy has been installed at the Jet Propulsion Laboratory's Table Mountain Facility (34.4N, 117.7 W, elevation 2290m).

Cageao, R.; Sander, S.; Blavier, J.; Jiang, Y.; Nemtchinov, V.

2000-01-01

264

EVALUATION OF THE FOURIER TRANSFORM INFRARED SPECTROMETER FOR PARTICLE-ASSOCIATED AMMONIUM SULFATE DETERMINATION  

EPA Science Inventory

A commercial Fourier transform infrared (FTIR) spectrometer, modified for automated analysis of particulate-associated sulfate, was used to obtain transmission spectra samples of particulate matter collected from the ambient air onto Teflon filters. n evaluation of this instrumen...

265

QUANTITATIVE FOURIER TRANSFORM INFRARED SPECTROSCOPIC INVESTIGATION OF HUMIC SUBSTANCE FUNCTIONAL GROUP COMPOSITION  

EPA Science Inventory

Infrared (IR) spectroscopy has been widely used for the structural investigation of humic substances. Although Fourier Transform Infrared (FTIR) instrumentation has been available for sometime, relatively little work with these instruments has been reported for humic substances,...

266

Forecasting performance of denoising signal by Wavelet and Fourier Transforms using SARIMA model  

NASA Astrophysics Data System (ADS)

The goal of this research is to determine the forecasting performance of denoising signal. Monthly rainfall and monthly number of raindays with duration of 20 years (1990-2009) from Bayan Lepas station are utilized as the case study. The Fast Fourier Transform (FFT) and Wavelet Transform (WT) are used in this research to find the denoise signal. The denoise data obtained by Fast Fourier Transform and Wavelet Transform are being analyze by seasonal ARIMA model. The best fitted model is determined by the minimum value of MSE. The result indicates that Wavelet Transform is an effective method in denoising the monthly rainfall and number of rain days signals compared to Fast Fourier Transform.

Ismail, Mohd Tahir; Mamat, Siti Salwana; Hamzah, Firdaus Mohamad; Karim, Samsul Ariffin Abdul

2014-07-01

267

Midwave infrared imaging Fourier transform spectrometry of combustion plumes  

NASA Astrophysics Data System (ADS)

A midwave infrared (MWIR) imaging Fourier transform spectrometer (IFTS) was used to successfully capture and analyze hyperspectral imagery of combustion plumes. Jet engine exhaust data from a small turbojet engine burning diesel fuel at a low rate of 300 cm3/min was collected at 1 cm -1 resolution from a side-plume vantage point on a 200x64 pixel window at a range of 11.2 meters. Spectral features of H2O, CO, and CO2 were present, and showed spatial variability within the plume structure. An array of thermocouple probes was positioned within the plume to aid in temperature analysis. A single-temperature plume model was implemented to obtain spatially-varying temperatures and plume concentrations. Model-fitted temperatures of 811 +/- 1.5 K and 543 +/- 1.6 K were obtained from plume regions in close proximity to thermocouple probes measuring temperatures of 719 K and 522 K, respectively. Industrial smokestack plume data from a coal-burning stack collected at 0.25 cm-1 resolution at a range of 600 meters featured strong emission from NO, CO, CO2, SO 2, and HCl in the spectral region 1800-3000 cm-1. A simplified radiative transfer model was employed to derive temperature and concentrations for clustered regions of the 128x64 pixel scene, with corresponding statistical error bounds. The hottest region (closest to stack centerline) was 401 +/- 0.36 K, compared to an in-stack measurement of 406 K, and model-derived concentration values of NO, CO2, and SO2 were 140 +/- 1 ppmV, 110,400 +/- 950 ppmV, and 382 +/- 4 ppmV compared to in-stack measurements of 120 ppmV (NOx), 94,000 ppmV, and 382 ppmV, respectively. In-stack measurements of CO and HCl were not provided by the stack operator, but model-derived values of 19 +/- 0.2 ppmV and 111 +/- 1 ppmV are reported near stack centerline. A deployment to Dugway Proving Grounds, UT to collect hyperspectral imagery of chemical and biological threat agent simulants resulted in weak spectral signatures from several species. Plume detection of methyl salicilate was achieved from both a stack release and explosive detonation, although spectral identification was not accomplished due to weak signal strength.

Bradley, Kenneth C.

268

High signal-to-noise Fourier transform spectroscopy with light emitting diode sources  

NASA Astrophysics Data System (ADS)

A temperature tuned light emitting diode (LED) has several advantages over conventional sources for Fourier transform spectroscopy. The large radiation density of LEDs, concentrated in a small spectral region, is ideal for high resolution Fourier transform spectroscopy where a high signal-to-noise (S/N) ratio is desired. A simple, inexpensive LED source leads to a superior performance at high resolutions exceeding that of a tungsten halogen lamp, in the visible region of spectrum.

Bhosale, J. S.

2011-09-01

269

A surface acoustic wave device for obtaining direct electronic Fourier transforms of images  

Microsoft Academic Search

A one-dimensional acoustic surface wave direct electronic Fourier transform (DEFT) camera was fabricated and evaluated. This device employs the elastophotoconductance mechanism (the interaction of a surface acoustic wave with a photo-conductive CdS polycrystalline film), creating electrical signals proportional to a spatial Fourier transform of the image incident on it. In this device, the surface acoustic wave is generated by a

N. T. Yang

1974-01-01

270

An uncertainty principle for real signals in the fractional Fourier transform domain  

Microsoft Academic Search

The fractional Fourier transform (FrFT) can be thought of as a generalization of the Fourier transform to rotate a signal representation by an arbitrary angle ? in the time-frequency plane. A lower bound on the uncertainty product of signal representations in two FrFT domains for real signals is obtained, and it is shown that a Gaussian signal achieves the lower

Sudarshan Shinde; Vikram M. Gadre

2001-01-01

271

Note: Phase sensitive detection of photoluminescence with Fourier transform spectroscopy.  

PubMed

Although known for more than twenty years, there is limited information in the literature regarding the experimental parameters of lock-in based phase sensitive emission detection in conjunction with Fourier spectrometers. For this technique - also known as double modulation spectroscopy - we present a guideline for parameter optimization by measuring the photoluminescence of InSb:Te at cryogenic temperatures. PMID:22300001

Ullrich, B; Brown, G J

2012-01-01

272

A Fast Algorithm for Nonequispaced Fourier Transforms on the Rotation Group  

E-print Network

transforms on the rotation group SO(3) motivated by a variety of applications, like protein-protein Definition 2.1) each as Dm,n l (g) = e-im e-in dm,n l (cos ) we use the nonequispaced fast Fourier transform

Prestin, Jürgen

273

Propagation properties of Bessel and Bessel-Gaussian beams in a fractional Fourier transform optical system  

NASA Astrophysics Data System (ADS)

The properties of Bessel-Gaussian beams (BGBs) and Bessel beams (BBs) propagating through a fractional Fourier transform (FRT) optical system have been investigated. The analytical transformation formulae for BBs and BGBs propagation through a FRT optical system are derived based on definition of the FRT in the cylindrical coordinate system. By using the derived formula, numerical examples are illustrated.

Zhao, Chengliang; Huang, Kaikai; Lu, Xuanhui

2010-03-01

274

A Graphical Presentation to Teach the Concept of the Fourier Transform  

ERIC Educational Resources Information Center

A study was conducted to visualize the reason why the Fourier transform technique is useful to detect the originating frequencies of a complicated superposition of waves. The findings reveal that students respond well when instructors adapt pictorial presentation to show how the time-domain function is transformed into the frequency domain.

Besalu, E.

2006-01-01

275

Evaluation of Fourier cosine/sine transforms using exponentially positioned samples  

NASA Astrophysics Data System (ADS)

The digital filter technique using exponentially positioned samples has been widely used in evaluating Hankel transforms. However it is not so widely used in evaluating Fourier transforms (FT). Published actual filters for FT evaluation are rather limited. We therefore present filters in lengths: 21, 61 and 101, which may be useful in evaluating FT for calculating e.g., the electromagnetic fields from a line source and from a dipole source, etc. It is shown that the filter technique can be more efficient (i.e., using fewer samples) than using digital Fourier transform (DFT) in evaluating FT related to 2D and 3D Green's functions.

Kong, F. N.

2012-04-01

276

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

277

Optical movie encryption based on a discrete multiple-parameter fractional Fourier transform  

NASA Astrophysics Data System (ADS)

A movie encryption scheme is proposed using a discrete multiple-parameter fractional Fourier transform and theta modulation. After being modulated by sinusoidal amplitude grating, each frame of the movie is transformed by a filtering procedure and then multiplexed into a complex signal. The complex signal is multiplied by a pixel scrambling operation and random phase mask, and then encrypted by a discrete multiple-parameter fractional Fourier transform. The movie can be retrieved by using the correct keys, such as a random phase mask, a pixel scrambling operation, the parameters in a discrete multiple-parameter fractional Fourier transform and a time sequence. Numerical simulations have been performed to demonstrate the validity and the security of the proposed method.

Zhong, Zhi; Zhang, Yujie; Shan, Mingguang; Wang, Ying; Zhang, Yabin; Xie, Hong

2014-12-01

278

Products of multiple Fourier series with application to the multiblade transformation  

NASA Technical Reports Server (NTRS)

A relatively simple and systematic method for forming the products of multiple Fourier series using tensor like operations is demonstrated. This symbolic multiplication can be performed for any arbitrary number of series, and the coefficients of a set of linear differential equations with periodic coefficients from a rotating coordinate system to a nonrotating system is also demonstrated. It is shown that using Fourier operations to perform this transformation make it easily understood, simple to apply, and generally applicable.

Kunz, D. L.

1981-01-01

279

Fourier-transform spectroscopy: new methods and applications: introduction by the feature editors  

NASA Astrophysics Data System (ADS)

We are pleased to introduce this special issue of papers on Fourier-transform spectroscopy, which grew out of a recent topical meeting sponsored by the Optical Society of America. The topical meeting welcomed all researchers who practice the art of Fourier-transform spectroscopy in the laboratory, in the atmosphere, and in space. The power and the wide applicability of Fourier-transform spectroscopy unite these fields with a common mathematical and instrumental bond. The meeting probed each of these areas in depth, bringing out new ideas for instrumentation, analysis, and applications. There was a strong sentiment at the meeting that the quality of papers and posters was exceptionally high and that it would be important for future progress in the field to have the results of this meeting captured in print. This special issue is the fruit of that effort.

Traub, Wesley A.; Winkel, Raymond J., Jr.; Goldman, Aaron

1996-06-01

280

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

281

Application and sensitivity investigation of Fourier transforms for microwave radiometric inversions  

NASA Technical Reports Server (NTRS)

Existing microwave radiometer technology now provides a suitable method for remote determination of the ocean surface's absolute brightness temperature. To extract the brightness temperature of the water from the antenna temperature equation, an unstable Fredholm integral equation of the first kind was solved. Fast Fourier Transform techniques were used to invert the integral after it is placed into a cross-correlation form. Application and verification of the methods to a two-dimensional modeling of a laboratory wave tank system were included. The instability of the Fredholm equation was then demonstrated and a restoration procedure was included which smooths the resulting oscillations. With the recent availability and advances of Fast Fourier Transform techniques, the method presented becomes very attractive in the evaluation of large quantities of data. Actual radiometric measurements of sea water are inverted using the restoration method, incorporating the advantages of the Fast Fourier Transform algorithm for computations.

Holmes, J. J.; Balanis, C. A.

1974-01-01

282

Does the entorhinal cortex use the Fourier transform?  

PubMed Central

Some neurons in the entorhinal cortex (EC) fire bursts when the animal occupies locations organized in a hexagonal grid pattern in their spatial environment. Place cells have also been observed, firing bursts only when the animal occupies a particular region of the environment. Both of these types of cells exhibit theta-cycle modulation, firing bursts in the 4–12 Hz range. Grid cells fire bursts of action potentials that precess with respect to the theta cycle, a phenomenon dubbed “theta precession.” Various models have been proposed to explain these phenomena, and how they relate to navigation. Among the most promising are the oscillator interference models. The bank-of-oscillators model proposed by Welday et al. (2011) exhibits all these features. However, their simulations are based on theoretical oscillators, and not implemented entirely with spiking neurons. We extend their work in a number of ways. First, we place the oscillators in a frequency domain and reformulate the model in terms of Fourier theory. Second, this perspective suggests a division of labor for implementing spatial maps: position vs. map layout. The animal's position is encoded in the phases of the oscillators, while the spatial map shape is encoded implicitly in the weights of the connections between the oscillators and the read-out nodes. Third, it reveals that the oscillator phases all need to conform to a linear relationship across the frequency domain. Fourth, we implement a partial model of the EC using spiking leaky integrate-and-fire (LIF) neurons. Fifth, we devise new coupling mechanisms, enlightened by the global phase constraint, and show they are capable of keeping spiking neural oscillators in consistent formation. Our model demonstrates place cells, grid cells, and phase precession. The Fourier model also gives direction for future investigations, such as integrating sensory feedback to combat drift, or explaining why grid cells exist at all. PMID:24376415

Orchard, Jeff; Yang, Hao; Ji, Xiang

2013-01-01

283

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

284

Quantum Energy Regression using Scattering Transforms  

E-print Network

We present a novel approach to the regression of quantum mechanical energies based on a scattering transform of an intermediate electron density representation. A scattering transform is a deep convolution network computed with a cascade of multiscale wavelet transforms. It possesses appropriate invariant and stability properties for quantum energy regression. This new framework removes fundamental limitations of Coulomb matrix based energy regressions, and numerical experiments give state-of-the-art accuracy over planar molecules.

Hirn, Matthew; Mallat, Stephane

2015-01-01

285

A small box Fast Fourier Transformation method for fast Poisson solutions in large systems  

NASA Astrophysics Data System (ADS)

We present a new divide-and-conquer algorithm to efficiently evaluate the Coulomb interaction in a large system, which is an essential part of self-consistent first-principle calculations. The total Coulomb potential ?(r)=1/|r| is divided into a short range part ?S(r) and a smooth long range part ?L(r). The system is divided into many cuboids, with a small box defined for each cuboid plus a buffer region. For the short range part, the interaction convolution integral is calculated directly using a Fast Fourier Transformation (FFT) in the small box. For the smooth long range part, the convolution integral is evaluated by a global FFT but on a coarse grid. The conversion between the dense grid and coarse grid values is done using small box FFTs with proper mask functions. Using this small box FFT method, the total Coulomb potentials of test quantum dot systems on 4803 grid and 24003 grid are calculated. For the 24003 grid case, the calculation is carried out by tens of thousands of processors with a computational speed up close to 10 times when compared with direct global FFT calculations using the FFTW package with the maximumly allowed number of processors. The maximum relative error is 4×10-5 while the absolute error is less than 0.1 meV.

Jiang, Xiang-Wei; Li, Shu-Shen; Wang, Lin-Wang

2013-12-01

286

Fourier transform synchrotron spectroscopy of torsional and CO-stretching bands of CH 3 17 OH  

NASA Astrophysics Data System (ADS)

The Fourier transform spectrum of the CH 317OH isotopologue of methanol has been recorded in the 65-1200 cm -1 spectral region at a resolution of 0.00096 cm -1 using synchrotron source radiation at the Canadian Light Source. Here we present an extension to higher torsional states of our investigation of the torsion-rotation transitions within the small-amplitude vibrational ground state, now including assignments of more than 16 500 lines involving quantum numbers in the ranges v t ? 3, J ? 30 and | K| ? 12, as well as a study of the strong CO-stretching band centered at 1020 cm -1. Energy term values have been determined for assigned ground and CO-stretching levels by use of the Ritz program, and have been fitted to series expansions in powers of J( J + 1) to determine substate origins and effective B values. Several Fermi anharmonic and Coriolis level-crossing resonances coupling the CO stretch with high torsional ground-state levels have been identified and characterized. The study is motivated by astrophysical applications, with a principal aim being the compilation of an extensive set of energy term values to permit prediction of astronomically observable sub-millimetre transitions to within an uncertainty of a few MHz.

Moruzzi, G.; Murphy, R. J.; Vos, J.; Lees, R. M.; Predoi-Cross, A.; Billinghurst, B. E.

2011-07-01

287

On Fourier integral transforms for q-Fibonacci and q-Lucas polynomials  

NASA Astrophysics Data System (ADS)

We study in detail two families of q-Fibonacci polynomials and q-Lucas polynomials, which are defined by non-conventional three-term recurrences. They were recently introduced by Cigler and were then employed by Cigler and Zeng to construct novel q-extensions of classical Hermite polynomials. We show that both of these q-polynomial families exhibit simple transformation properties with respect to the classical Fourier integral transform.

Atakishiyev, Natig; Franco, Pedro; Levi, Decio; Ragnisco, Orlando

2012-05-01

288

On Fourier integral transforms for $q$-Fibonacci and $q$-Lucas polynomials  

E-print Network

We study in detail two families of $q$-Fibonacci polynomials and $q$-Lucas polynomials, which are defined by non-conventional three-term recurrences. They were recently introduced by Cigler and have been then employed by Cigler and Zeng to construct novel $q$-extensions of classical Hermite polynomials. We show that both of these $q$-polynomial families exhibit simple transformation properties with respect to the classical Fourier integral transform.

Atakishiyev, Natig; Levi, Decio; Ragnisco, Orlando

2011-01-01

289

Development of Scanning-Type X-ray Fourier Transform Holography  

NASA Astrophysics Data System (ADS)

We developed a scanning-type x-ray Fourier transform holography and applied it to both the soft and hard x-ray regions. For this approach, we prepared the holography mask and the imaging object separately and placed them in contact with each other. In this configuration, the illuminated area can be changed by moving the sample relative to the mask via the translation stage. In this case, an image can be recovered by Fourier inversion of the hologram as in the usual lensless Fourier transform holography. This method also reduces the relative vibration between the mask and sample, and provides good quality images. The method was successfully applied to large-area imaging of magnetic domains in a Co/Pt perpendicular magnetic film with soft x-rays. In addition, cross-sectional imaging of Cu interconnect lines was performed in the hard x-ray region.

Nomura, K.; Awaji, N.; Doi, S.; Isogami, S.; Kodama, K.; Nakamura, T.; Suzuki, M.; Tsunoda, M.

2011-09-01

290

Fast Inverse Nonlinear Fourier Transform For Generating Multi-Solitons In Optical Fiber  

E-print Network

The achievable data rates of current fiber-optic wavelength-division-multiplexing (WDM) systems are limited by nonlinear interactions between different subchannels. Recently, it was thus proposed to replace the conventional Fourier transform in WDM systems with an appropriately defined nonlinear Fourier transform (NFT). The computational complexity of NFTs is a topic of current research. In this paper, a fast inverse NFT algorithm for the important special case of multi-solitonic signals is presented. The algorithm requires only $\\mathcal{O}(D\\log^{2}D)$ floating point operations to compute $D$ samples of a multi-soliton. To the best of our knowledge, this is the first algorithm for this problem with $\\log^{2}$-linear complexity. The paper also includes a many samples analysis of the generated nonlinear Fourier spectra.

Wahls, Sander

2015-01-01

291

Determination of phospholipid content of intramuscular fat by Fourier Transform Infrared spectroscopy  

Microsoft Academic Search

A method has been developed to determine the phospholipid content in fat extract with FTIR (Fourier Transform Infrared). l-?-Phosphatidylcholine from egg yolk in hexane solution was used as a reference for band identification at different concentrations. Phosphate bands were determined at different wavenumbers as described in the literature. A dilution series was made from meat extract and from 1-?-phosphatidylcholine. A

H. Villé; G. Maes; R. De Schrijver; G. Spincemaille; G. Rombouts; R. Geers

1995-01-01

292

Applications of Fourier transform infrared spectroscopy to in situ catalyst surface studies  

Microsoft Academic Search

Fourier transform infrared spectroscopy (FTIR) is a powerful tool for studying surface species present on supported catalysts during normal reaction conditions of high temperature and\\/or pressure. A special high-throughput optical bench has been used to optimize the sensitivity of this system for high optical density catalyst samples. The infrared cell is designed to operate at high vacuum for adsorption studies

David M. Haaland; Frank L. Williams

1981-01-01

293

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

E-print Network

Far infrared Fourier-transform spectroscopy of mono-deuterated hydrogen peroxide HOOD Doris-1, Tsukuba, Ibaraki 305-8569, Japan a r t i c l e i n f o Keywords: Deuterated hydrogen peroxide Far infrared phase spectrum of singly deuterated hydrogen peroxide, HOOD, in its vibrational ground state, recorded

Giesen, Thomas

294

Study on europium doped hydroxyapatite nanoparticles by Fourier transform infrared spectroscopy and their antimicrobial properties  

E-print Network

Study on europium doped hydroxyapatite nanoparticles by Fourier transform infrared spectroscopy were conducted on europium doped hydroxyapatite, Ca10-xEux(PO4)6(OH)2 nanocrystalline powders (Eu demonstrates that the antimicrobial activity of Eu:HAp nanoparticles is dependent on the europium concentration

Boyer, Edmond

295

Title: Crack Diagnostics via Fourier Transform: Real and Imaginary Components vs. Power Spectral Density  

E-print Network

Title: Crack Diagnostics via Fourier Transform: Real and Imaginary Components vs. Power Spectral examples based on the analysis of synthetic signals generated using the nonlinear model of a cracked part crack of various relative sizes. The numerical examples show that the detection, based on Fisher

Giurgiutiu, Victor

296

Rendering falling snow using an inverse Fourier transform Michael S. Langer  

E-print Network

Rendering falling snow using an inverse Fourier transform Michael S. Langer School of Computer snow, non-photorealistic rendering Methods for rendering falling snow typically use particle sys- tems we present an alter- native method for rendering falling snow which does not use parti- cles

Langer, Michael

297

COCHANNEL FM DEMODULATION VIA THE MULTI ANGLE-CENTERED DISCRETE FRACTIONAL FOURIER TRANSFORM  

E-print Network

COCHANNEL FM DEMODULATION VIA THE MULTI ANGLE-CENTERED DISCRETE FRACTIONAL FOURIER TRANSFORM S. L- poses of cochannel FM demodulation and also investigate its use for the demodulation of cochannel to accomplish cochannel signal separation and demodulation, where existing multicomponent AM­FM demod- ulation

Santhanam, Balu

298

Two-dimensional ultrafast fourier transform spectroscopy in the deep ultraviolet.  

PubMed

We demonstrate two-dimensional ultrafast fourier transform spectroscopy in the deep ultraviolet (approximately 260 nm) using an acousto-optic modulator based pulse shaper. The use of a pulse shaper in the ultraviolet allows for rapid scanning, high phase (time) stability (approximately 0.017 rad) and phase cycling. We present measurements on the DNA nucleobase Adenine. PMID:20372612

Tseng, Chien-hung; Matsika, Spiridoula; Weinacht, Thomas C

2009-10-12

299

Degradation of polymer/substrate interfaces an attenuated total reflection Fourier transform infrared spectroscopy approach  

E-print Network

for #12;iii polymer swelling, delamination and corrosion of the aluminum film under the polymer layer. On the contrary, delamination/swelling of the polymer was not observed at the eponol-aluminum interface, althoughDegradation of polymer/substrate interfaces ­ an attenuated total reflection Fourier transform

300

Alpha-rooting method of color image enhancement by discrete quaternion Fourier transform  

NASA Astrophysics Data System (ADS)

This paper presents a novel method for color image enhancement based on the discrete quaternion Fourier transform. We choose the quaternion Fourier transform, because it well-suited for color image processing applications, it processes all 3 color components (R,G,B) simultaneously, it capture the inherent correlation between the components, it does not generate color artifacts or blending , finally it does not need an additional color restoration process. Also we introduce a new CEME measure to evaluate the quality of the enhanced color images. Preliminary results show that the ?-rooting based on the quaternion Fourier transform enhancement method out-performs other enhancement methods such as the Fourier transform based ?-rooting algorithm and the Multi scale Retinex. On top, the new method not only provides true color fidelity for poor quality images but also averages the color components to gray value for balancing colors. It can be used to enhance edge information and sharp features in images, as well as for enhancing even low contrast images. The proposed algorithms are simple to apply and design, which makes them very practical in image enhancement.

Grigoryan, Artyom M.; Agaian, Sos S.

2014-02-01

301

Analysis of power system dynamic oscillations with heat phenomenon by Fourier transformation  

Microsoft Academic Search

When two or more poorly damped oscillation modes of close-by frequencies are excited, beat phenomena occur. The stability output Fourier transformation (SOFT) technique is extended to analyze such beat phenomena with the objective of determining the frequency components and their damping constants. Comparisons with other numerical techniques for dynamic stability are presented. Further work for the improvement of the optimization

K. C. Lee; K. P. Poon

1990-01-01

302

$(p,q)-$deformed Fibonacci and Lucas polynomials: characterization and Fourier integral transforms  

E-print Network

A full characterization of $(p,q)$-deformed Fibonacci and Lucas polynomials is given. These polynomials obey non-conventional three-term recursion relations. Their generating functions and Fourier integral transforms are explicitly computed and discussed. Relevant results known in the literature are examined as particular cases.

Mahouton Norbert Hounkonnou; Sama Arjika

2013-07-09

303

Fourier-transform photocurrent spectroscopy using a supercontinuum light Christian Petermann, Rene Beigang, and Peer Fischer  

E-print Network

Fourier-transform photocurrent spectroscopy using a supercontinuum light source Christian Petermann a supercontinuum light source Christian Petermann,1,a) Rene Beigang,2 and Peer Fischer3 1 Fraunhofer Institute demonstrate an implementation of frequency-encoded photocurrent spectroscopy using a super-continuum light

304

Parasitic diffuse reflection in a Fourier transform spectrometer yielding subharmonic ghosts and line-shape distortion  

Microsoft Academic Search

When using a high-resolution Fourier transform spectrometer (FTS) in a cube-corner configuration, subharmonic ghosts are observed in the spectrum. These ghosts are attributable to parasitic diffuse reflections on the mirrors of the FTS arm. The reflected beams skip a part of the interferometer and travel a different path from the main beam thus experiencing a smaller optomechanical gain. These reflections

Geneviève Taurand; Jérôme Genest; Maxime Cadotte; Mathieu Gibeault; Éric Lanoue

2007-01-01

305

Broad-band spectroscopy with the James Clerk Maxwell Telescope using a polarizing Fourier transform spectrometer  

Microsoft Academic Search

We report the first use of a polarizing Fourier transform spectrometer on the James Clerk Maxwell Telescope. Solar spectra have been measured through four of the submillimeter and millimeter atmospheric windows. The repeatability is shown to be excellent, with signal-to-noise ratios exceeding 100 per spectral element per scan. The spectra also show good agreement with synthetic atmospheric transmission spectra over

D. A. Naylor; T. A. Clark; G. R. Davis; W. D. Duncan; G. J. Tompkins

1993-01-01

306

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

307

A Fast Fourier Transform with Rectangular Output on the BCC and FCC Lattices  

E-print Network

A Fast Fourier Transform with Rectangular Output on the BCC and FCC Lattices Usman R. Alim (1 and yields a 30% savings in samples as compared to the Cartesian lattice [8]. The Face-Centered Cubic (FCC]. From the perspective of continuous signal reconstruction, both the BCC and FCC lattices have received

Alim, Usman Raza

308

On the use of windows for harmonic analysis with the discrete Fourier transform  

Microsoft Academic Search

This paper makes available a concise review of data windows and their affect on the detection of harmonic signals in the presence of broad-band noise, and in the presence of nearby strong harmonic interference. We also call attention to a number of common errors in the application of windows when used with the fast Fourier transform. This paper includes a

FREDRIC J. HARRIS

1978-01-01

309

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-...

310

Characteristic Length Scale of Bicontinuous Nanoporous Structure by Fast Fourier Transform  

Microsoft Academic Search

We propose a method derived from fast Fourier transform (FFT) process to measure the characteristic length scale of bicontinuous nanoporous structures. By rotationally averaging the FFT power spectrum of a nanoporous micrograph from scanning electron microscope (SEM) or transmission electron microscope (TEM), a significant peak in the power spectrum can be obtained, which reflects the characteristic length scale of the

Takeshi Fujita; Ming Wei Chen

2008-01-01

311

The Fourier transform solution for the Green's function of monoenergetic neutron transport theory  

E-print Network

Nearly 45 years ago, Ken Case published his seminal paper on the singular eigenfunction solution for the Green's function of the monoenergetic neutron transport equation with isotropic scattering. Previously, the solution had been obtained by Fourier transform. While it is apparent the two had to be equivalent, a convincing equivalence proof for general anisotropic scattering remained a challenge until now.

Barry D. ganapol

2014-03-17

312

PARTICULATE MATTER MEASUREMENTS USING OPEN-PATH FOURIER TRANSFORM INFRARED SPECTROSCOPY  

EPA Science Inventory

Open-path Fourier transform infrared (OP-FT1R) spectroscopy is an accepted technology for measuring gaseous air contaminants. OP-FT1R absorbance spectra acquired during changing aerosols conditions reveal related changes in very broad baseline features. Usually, this shearing of ...

313

THE FUTURE FAST FOURIER TRANSFORM? ALAN EDELMAN, PETER McCORQUODALE, AND SIVAN TOLEDO  

E-print Network

THE FUTURE FAST FOURIER TRANSFORM? ALAN EDELMAN, PETER McCORQUODALE, AND SIVAN TOLEDO§ SIAM J. SCI subject classifications. 65T20, 65Y05, 65Y20 PII. S1064827597316266 1. Introduction. In future high improvements in com- munication bandwidth. Therefore, important algorithms for the future may trade off

Edelman, Alan

314

Fourier-transform spectroscopy of O3 in the 3-micron region  

NASA Technical Reports Server (NTRS)

Fourier transform spectra of ozone have been recorded in the 2-5-micron region at a resolution of 0.01/cm. Absorption lines belonging to numerous vibration-rotation transitions have been observed in these spectra, and a detailed analysis of the band system centered at 3.6 microns has been completed.

Smith, M. A. H.; Rinsland, C. P.; Malathy Devi, V.; Flaud, J.-M.; Camy-Peyret, C.

1989-01-01

315

Application of Fourier transform infrared spectroscopy to determine free fatty acid contents in palm olein  

Microsoft Academic Search

A simple and rapid method for the quantitative determination of free fatty acid (FFA) contents in palm olein by Fourier transform infrared (FTIR) transmission spectroscope is described. A set of palm olein samples is used as the calibration set. This set was prepared by spiking increasing amounts of oleic acid into a series of palm oleins that covers a wide

Y. B. Che Man; G. Setiowaty

1999-01-01

316

Comparison of FourierTransform Infrared Spectroscopic Screening of Exfoliated Cervical Cells with Standard Papanicolaou Screening  

Microsoft Academic Search

To compare Fourier-transform infrared (FTIR) spectroscopy in screening cervical cytology and standard Papanicolaou (Pap) screening with colposcopic directed biopsy as a “gold standard,” we prospectively gathered FTIR samples and Pap smears of all patients attending our program's colposcopy clinics, from February to October 1995. We recorded demographic data for each patient including colposcopy, cytology, treatment follow-up, and histology. Using the

Michael Fung Kee Fung; Mary Senterman; Pascale Eid; Wylam Faught; Nadia Z. Mikhael; Patrick T. T. Wong

1997-01-01

317

Memory Bandwidth Efficient Two-Dimensional Fast Fourier Transform Algorithm and Implementation for Large Problem Sizes  

E-print Network

throughput and off-chip memory bandwidth. An efficient use of memory bandwidth must become a first-based implementations of two-dimensional fast Fourier transform (2D-FFT) where the large datasets must reside off-chip only a portion of the dataset that fits on-chip is operated on at a time, requiring data elements

Franchetti, Franz

318

ATMOSPHERIC MEASUREMENTS OF TRACE POLLUTANTS; LONG PATH FOURIER TRANSFORM INFRARED SPECTROSCOPY  

EPA Science Inventory

Described are the results of a four-year study to measure trace pollutant concentrations in polluted atmospheres by kilometer pathlength Fourier transform infrared (FT-IR) absorption spectroscopy. The study covers selected smog episodes during the years 1976 to 1979. During 1976 ...

319

Laboratory Investigations An Examination of Triassic Cynodont Tooth Enamel Chemistry Using Fourier Transform Infrared Spectroscopy  

Microsoft Academic Search

The Cynodontia are considered to be partic- ularly significant as their remains document the reptile- to-mammal transition during the Permian and Triassic periods. Studies examining cynodont morphology and anatomy have shown that these animals acquired increasingly mammal-like characteristics during their evolution. In this study, we use Fourier Transform Infrared spectroscopy to assess the enamel structure of several Triassic cynodonts. Extant

J. Botha; J. Lee-Thorp; M. Sponheimer

2004-01-01

320

The Kinetics of Mo(Co)6 Substitution Monitored by Fourier Transform Infrared Spectrophotometry.  

ERIC Educational Resources Information Center

Describes a physical chemistry experiment that uses Fourier transform (FTIR) spectrometers and microcomputers as a way of introducing students to the spectral storage and manipulation techniques associated with digitized data. It can be used to illustrate FTIR spectroscopy, simple kinetics, inorganic mechanisms, and Beer's Law. (TW)

Suslick, Kenneth S.; And Others

1987-01-01

321

FOURIER TRANSFORM SPECTROSCOPY AS A CONTINUOUS MONITORING METHOD: A SURVEY OF APPLICATIONS AND PROSPECTS  

EPA Science Inventory

Several field tests of a Fourier transform infrared (FTIR) spectrometer have been conducted. he results indicate that effective use of this type of instrument in the field of continuous emissions monitoring (CEM) is possible under the proper conditions, and within limits currentl...

322

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

323

FOURIER TRANSFORM RAMAN SPECTROSCOPIC ANALYSIS OF LEAD-EXPOSED MUSCLE TISSUES OF CATLA CATLA  

Microsoft Academic Search

Lead is considered to be one of the most common toxic metals present in the environment, exposure to it being a major concern to public health. Fourier Transform (FT) Raman Spectroscopy can provide information on the molecular composition of a substance by detecting and analyzing light that is inelastically scattered from the substance following its excitation by monochromatic laser light.

M. VADIVELU; V. VIJAYASUNDARAM; Annamalai Nagar

2009-01-01

324

Ordered fast Fourier transforms on a massively parallel hypercube multiprocessor  

NASA Technical Reports Server (NTRS)

The present evaluation of alternative, massively parallel hypercube processor-applicable designs for ordered radix-2 decimation-in-frequency FFT algorithms gives attention to the reduction of computation time-dominating communication. A combination of the order and computational phases of the FFT is accordingly employed, in conjunction with sequence-to-processor maps which reduce communication. Two orderings, 'standard' and 'cyclic', in which the order of the transform is the same as that of the input sequence, can be implemented with ease on the Connection Machine (where orderings are determined by geometries and priorities. A parallel method for trigonometric coefficient computation is presented which does not employ trigonometric functions or interprocessor communication.

Tong, Charles; Swarztrauber, Paul N.

1991-01-01

325

Description of the absorption spectrum of bromine recorded by means of Fourier transform spectroscopy : the (B 303A00+u ~  

E-print Network

1685 Description of the absorption spectrum of bromine recorded by means of Fourier transform An in extenso analysis of the (B-X ) Br2 bromine absorption spectrum recorded by means of Fourier Transform and extensive studies of the (B-X) bromine system have already been made [2-6], in the paper of Barrow Clark

Paris-Sud XI, Université de

326

Progress Towards Chirped-Pulse Fourier Transform Thz Spectroscopy  

NASA Astrophysics Data System (ADS)

New opportunities are provided by the development of higher power THz frequency multiplier sources, the development of a broadband Chirped-Pulse FTMW spectroscopy technique at microwave and mm Wave frequencies, and recently demonstrated heterodyne hot electron bolometer detection technology in the THz frequency region with near quantum noise-limited performance and high spectral resolution. Combining these three technologies and extending the chirped-pulse technique to 0.85 THz enables a host of new applications. NIST is currently pursing applications as a point sensor for greenhouse gases, volatile organic compounds, and potentially human breath. The generation and detection of phase stable chirped pulses at 850 GHz will be demonstrated. A description of the experimental setup and preliminary data will be presented for nitrous oxide. G.G. Brown, B.C. Dian, K.O. Douglass, S.M. Geyer, S. Shipman and B.H. Pate, Rev.Sci.Instrum. 79 (2008) 053103. E. Gerecht, D. Gu, L. You, K.S. Yngvesson, IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES. 56, (2008) 1083.

Douglass, Kevin O.; Plusquellic, David F.; Gerecht, Eyal

2010-06-01

327

In-place self-sorting fast Fourier transform algorithm with local memory references  

NASA Astrophysics Data System (ADS)

An new algorithm for the fast Fourier transform is proposed. Its three main characteristics are: being in-place (no auxiliary storage is required), being self-sorting or in-order (no bit reversal is necessary), and having locality of reference (items whose addresses are near one another are referenced closed together in time). A simple Fortran 90 program is given to illustrate the algorithm. In our platform, its performance is similar to the conventional algorithm for small transforms, and about three times faster for large transforms.

Pérez-Jordá, José M.

1998-01-01

328

The Power of Strong Fourier Sampling: Quantum Algorithms for Affine Groups and Hidden Shifts  

Microsoft Academic Search

Many quantum algorithms, including Shor's celebrated factoring and discrete log algorithms, proceed by reduction to a hidden subgroup problem, in which an unknown subgroup H of a group G must be determined from a quantum state over G that is uniformly supported on a left coset of H. These hidden subgroup problems are typically solved by Fourier sampling: the quantum

Cristopher Moore; Daniel N. Rockmore; Alexander Russell; Leonard J. Schulman

2007-01-01

329

Discrimination of Unitary Transformations and Quantum Algorithms  

E-print Network

Quantum algorithms are typically understood in terms of the evolution of a multi-qubit quantum system under a prescribed sequence of unitary transformations. The input to the algorithm prescribes some of the unitary transformations in the sequence with others remaining fixed. For oracle query algorithms, the input determines the oracle unitary transformation. Such algorithms can be regarded as devices for discriminating amongst a set of unitary transformations. The question arises: "Given a set of known oracle unitary transformations, to what extent is it possible to discriminate amongst them?" We investigate this for the Deutsch-Jozsa problem. The task of discriminating amongst the admissible oracle unitary transformations results in an exhaustive collection of algorithms which can solve the problem with certainty.

David Collins

2008-11-09

330

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

PubMed

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. PMID:12232436

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

1994-12-01

331

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. PMID:12232436

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

1994-01-01

332

Fourier Transform of the Stretched Exponential Function: Analytic Error Bounds, Double Exponential Transform, and Open-Source Implementation libkww  

E-print Network

The C library \\texttt{libkww} provides functions to compute the Kohlrausch-Williams-Watts function, i.e.\\ the Laplace-Fourier transform of the stretched (or compressed) exponential function $\\exp(-t^\\beta)$ for exponents $\\beta$ between 0.1 and 1.9 with sixteen-digits accuracy. Analytic error bounds are derived for the low and high frequency series expansions. For intermediate frequencies the numeric integration is enormously accelerated by using the Ooura-Mori double exponential transformation. The source code is available from the project home page \\url{http://apps.jcns.fz-juelich.de/doku/sc/kww}.

Joachim Wuttke

2012-09-01

333

A fast partial Fourier transform (FPFT) for data compression and filtering.  

SciTech Connect

A discrete Fourier transform (DFT) or the closely related discrete cosine transform (DCT) is often employed as part of a data compression scheme. This paper presents a fast partial Fourier transform (FPFT) algorithm that is useful for calculating a subset of M Fourier transform coefficients for a data set comprised of N points (M < N). This algorithm reduces to the standard DFT when M = 1 and it reduces to the radix-2, decimation-in-time FFT when M = N and N is a power of 2. The DFT requires on the order of MN complex floating point multiplications to calculate M coefficients for N data points, a complete FFT requires on the order of (N/2)log{sub 2}N multiplications independent of M, and the new FPFT algorithm requires on the order of (N/2)log{sub 2}M + N multiplications. The FPFT algorithm introduced in this paper could be readily adapted to parallel processing. In addition to data compression, the FPFT algorithm described in this paper might be useful for very narrow band filter operations that pass only a small number of non-zero frequency coefficients such that M << N.

Smith, Mark William

2010-07-01

334

Program for the analysis of time series. [by means of fast Fourier transform algorithm  

NASA Technical Reports Server (NTRS)

A digital computer program for the Fourier analysis of discrete time data is described. The program was designed to handle multiple channels of digitized data on general purpose computer systems. It is written, primarily, in a version of FORTRAN 2 currently in use on CDC 6000 series computers. Some small portions are written in CDC COMPASS, an assembler level code. However, functional descriptions of these portions are provided so that the program may be adapted for use on any facility possessing a FORTRAN compiler and random-access capability. Properly formatted digital data are windowed and analyzed by means of a fast Fourier transform algorithm to generate the following functions: (1) auto and/or cross power spectra, (2) autocorrelations and/or cross correlations, (3) Fourier coefficients, (4) coherence functions, (5) transfer functions, and (6) histograms.

Brown, T. J.; Brown, C. G.; Hardin, J. C.

1974-01-01

335

A Discussion of the Discrete Fourier Transform Execution on a Typical Desktop PC  

NASA Technical Reports Server (NTRS)

This paper will discuss and compare the execution times of three examples of the Discrete Fourier Transform (DFT). The first two examples will demonstrate the direct implementation of the algorithm. In the first example, the Fourier coefficients are generated at the execution of the DFT. In the second example, the coefficients are generated prior to execution and the DFT coefficients are indexed at execution. The last example will demonstrate the Cooley- Tukey algorithm, better known as the Fast Fourier Transform. All examples were written in C executed on a PC using a Pentium 4 running at 1.7 Ghz. As a function of N, the total complex data size, the direct implementation DFT executes, as expected at order of N2 and the FFT executes at order of N log2 N. At N=16K, there is an increase in processing time beyond what is expected. This is not caused by implementation but is a consequence of the effect that machine architecture and memory hierarchy has on implementation. This paper will include a brief overview of digital signal processing, along with a discussion of contemporary work with discrete Fourier processing.

White, Michael J.

2006-01-01

336

Transformations between symmetric sets of quantum states  

E-print Network

We investigate probabilistic transformations of quantum states from a `source' set to a `target' set of states. Such transforms have many applications. They can be used for tasks which include state-dependent cloning or quantum state discrimination, and as interfaces between systems whose information encodings are not related by a unitary transform, such as continuous-variable systems and finite-dimensional systems. In a probabilistic transform, information may be lost or leaked, and we explain the concepts of leak and redundancy. Following this, we show how the analysis of probabilistic transforms significantly simplifies for symmetric source and target sets of states. In particular, we give a simple linear program which solves the task of finding optimal transforms, and a method of characterizing the introduced leak and redundancy in information-theoretic terms. Using the developed techniques, we analyse a class of transforms which convert coherent states with information encoded in their relative phase to symmetric qubit states. Each of these sets of states on their own appears in many well studied quantum information protocols. Finally, we suggest an asymptotic realization based on quantum scissors.

Vedran Dunjko; Erika Andersson

2012-06-22

337

A spectral synthesis method to suppress aliasing and calibrate for delay errors in Fourier transform correlators  

E-print Network

Context: Fourier transform (or lag) correlators in radio interferometers can serve as an efficient means of synthesising spectral channels. However aliasing corrupts the edge channels so they usually have to be excluded from the data set. In systems with around 10 channels, the loss in sensitivity can be significant. In addition, the low level of residual aliasing in the remaining channels may cause systematic errors. Moreover, delay errors have been widely reported in implementations of broadband analogue correlators and simulations have shown that delay errors exasperate the effects of aliasing. Aims: We describe a software-based approach that suppresses aliasing by oversampling the cross-correlation function. This method can be applied to interferometers with individually-tracking antennas equipped with a discrete path compensator system. It is based on the well-known property of interferometers where the drift scan response is the Fourier transform of the source's band-limited spectrum. Methods: In this p...

Kaneko, Tak

2008-01-01

338

A fast Fourier transform accelerated Ewald summation technique for the vector electromagnetic rectangular cavity Green's function  

NASA Astrophysics Data System (ADS)

A fast Fourier transform accelerated Ewald method for the computation of the vector electromagnetic rectangular cavity Green's function in terms of the electric field due to electric currents is presented and used in a boundary integral formulation. The Ewald summation technique suffers from the high-frequency breakdown when it is applied to Green's functions of wave problems. In the case of the rectangular cavity Green's function, the number of necessary terms in the spectral series grows, therefore, cubically with frequency for a given accuracy. To counteract the high-frequency breakdown, the evaluation of the spectral series is accelerated with an inverse fast Fourier transform in this work. At high frequencies, a speed-up of up to four orders of magnitude is achieved. As an application example, a reverberation chamber containing a metallic enclosure and a mode-stirrer is modeled.

Gruber, M. E.; Koenen, C.; Eibert, T. F.

2015-01-01

339

MightySat II.1 Fourier-transform hyperspectral imager payload performance  

NASA Astrophysics Data System (ADS)

Using a new microsat called MightySat II as a platform, Kestrel Corporation is designing and building the first Fourier transform hyperspectral imager (FTHSI) to be operated from a spacecraft. This payload will also be the first to fly on the Phillips Laboratory MightySat II spacecraft series, a new, innovative approach, to affordable space testing of high risk, high payoff technologies. Performance enhancements offered by the Fourier transform approach have shown it to be one of the more promising spaceborne hyperspectral concepts. Simulations of the payload's performance have shown that the instrument is capable of separating a wide range of subtle spectral differences. Variations in the return from the Georges Bank and shoals are discernible and various types of coastal grasses (sea oats and spartina) can be isolated against a sand background.

Otten, Leonard J.; Sellar, R. Glenn; Rafert, J. Bruce

1995-12-01

340

Raman spectroscopy of gases with a Fourier transform spectrometer: the spectrum of D2  

Microsoft Academic Search

A high-resolution Fourier transform spectrometer (FTS) has been used to record spontaneous incoherent laser Raman spectra of gases. The resolution, sensitivity, calibration accuracy, and spectral coverage achieved in these spectra demonstrate the viability of the FTS for Raman spectroscopy. Measurements from a spectrum of D2 containing both v = 0-0 and v = 1-0 transitions were fitted to the Dunham

Donald E. Jennings; A. Weber; J. W. Brault

1986-01-01

341

On Fourier integral transforms for q-Fibonacci and q-Lucas polynomials  

Microsoft Academic Search

We study in detail two families of q-Fibonacci polynomials and q-Lucas polynomials, which are defined by non-conventional three-term recurrences. They were recently introduced by Cigler and were then employed by Cigler and Zeng to construct novel q-extensions of classical Hermite polynomials. We show that both of these q-polynomial families exhibit simple transformation properties with respect to the classical Fourier integral

Natig Atakishiyev; Pedro Franco; Decio Levi; Orlando Ragnisco

2012-01-01

342

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

343

Techniques for Handling and Removal of Spectral Channels in Fourier Transform Synchrotron-Based Spectra  

SciTech Connect

Channel spectra are a big problem for those attempting to use synchrotron-based Fourier transform spectra for spectral lineshape studies. Due to the layout of the optical system at the CLS far-infrared beamline, the synchrotron beam undergoes unavoidable multiple reflections on the steering mirrors, beam splitter, several sets of windows, and filters. We present a method for eliminating channel spectra and compare the results of our technique with other methods available in the literature.

Ibrahim, Amr; Predoi-Cross, Adriana; Teillet, Philippe M. [University of Lethbridge, Department of Physics and Astronomy, 4401 University Drive, Lethbridge, AB, T1K 3M4 (Canada)

2010-02-03

344

Gas-phase Fourier Transform Far-Infrared Spectroscopy of Astrophycical Species  

Microsoft Academic Search

In the next future, space-based and ground-based missions will produced high spatial and spectral resolution data of the Universe. Consequently, laboratory measurements are necessary to complete the spectroscopic knowledge of important molecules. We have measured emission and absorption spectra of several species by Fourier transform spectroscopy in the range 60 - 600 cm-1 (2 - 20 THz) at Doppler-limited resolution.

O. Pirali; M. Vervloet

2003-01-01

345

Fourier Transform Far-Infrared Spectroscopy of the NH 2, NHD, and ND 2Radicals  

Microsoft Academic Search

The gas-phase far-infrared absorption spectra of the NH2, NHD, and ND2radicals have been observed in the 51–366 cm?1region with a high-resolution Fourier transform spectrometer. The NH2radical was generated in a multiple-traversal absorption cell by a dc discharge in an NH3and Ar mixture. A discharge in an NH3, D2, and Ar mixture was used for production of NHD and ND2. The

Isamu Morino; Kentarou Kawaguchi

1997-01-01

346

Three-dimensional fourier transformation calculation of the radiation dose received from a 60 Co source  

Microsoft Academic Search

Conclusion  A physical model and software for calculation of three-dimensional distribution of the absorbed dose (kerma) using the Fourier\\u000a transformation was developed. Approaches to approximate calculation of the point core of scattered photons in tissue-equivalent\\u000a medium were proposed, and the calculation errors were estimated.\\u000a \\u000a The developed method was used for determining the absorbed dose distribution in several typical cases. It was

V. N. Vasil'ev

1999-01-01

347

Micro-turbomachine driving an infrared polarization modulator for Fourier transform infrared spectroscopy  

Microsoft Academic Search

This paper describes the development of a micro-air-turbine-driven polarization modulator (MPM) for double modulation Fourier transform infrared spectroscopy (FT-IR). The MPM has a Au\\/Cr wire grid polarizer on the backside of a ? 5 mm n-type silicon turbine rotor. The MPM was fabricated using silicon bulk micromachining techniques such as photolithography and deep reactive ion etching (deep RIE). We completed

Motoaki HARA; Shuji TANAKA; M. Esashi

2001-01-01

348

Investigation of infrared Fourier-Transform spectroscopy for oral cancer detection  

E-print Network

in the detection of cancers of the breast, colon, rectum, cervix, prostate, testis, tongue, mouth, and skin at earlier stages, when treatment is more likely to be successful. Self- examinations for cancers of the breast and skin may also result in detection...INVESTIGATION OF INFRARED FOURIER-TRANSFORM SPECTROSCOPY FOR ORAL CANCER DETECTION A Thesis by KEVIN MICHAEL COONEY Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree...

Cooney, Kevin Michael

1998-01-01

349

Command and data handling system for the Panchromatic Fourier Transform Spectrometer  

Microsoft Academic Search

Panchromatic Fourier Transform Spectrometer (Pan-FTS) is an Instrument Incubator Program (IIP) funded development to build and demonstrate a single instrument capable of meeting or exceeding the requirements of the Geostationary Coastal and Air Pollution Events (GEO-CAPE) mission. Pan-FTS has recently started operation at Mt. Wilson, CA, providing atmospheric measurement capabilities in the IR and UV-VIS. The currently deployed instrument includes

Dmitriy L. Bekker; Jean-Francois L. Blavier; Dejian Fu; Richard W. Key; Ken S. Manatt; Colin McKinney; David M. Rider; Stanley P. Sander; Thomas A. Werne; Amy C. Wu; Yen-Hung Wu

2012-01-01

350

Fourier transform measurements of water vapor line parameters in the 4200–6600 cm ?1 region  

Microsoft Academic Search

New high-resolution water vapor absorption spectra were obtained at room temperature in the 4200–6600cm?1 spectral region by combining Fourier transform spectrometers (FTS) with single and multiple reflection cells. With absorption paths from 0.3 to 1800 m in pure and air diluted water vapor, accurate measurements of about 10400 lines in an intensity range from 10?29 to 10?19cm\\/molecule have been performed.

Alain Jenouvrier; Ludovic Daumont; Laurence Régalia-Jarlot; Vladimir G. Tyuterev; Michel Carleer; Ann Carine Vandaele; Semen Mikhailenko; Sophie Fally

2007-01-01

351

Fourier transform infrared spectroscopy and differential scanning calorimetry studies of fatty acid homogeneous ceramide 2  

Microsoft Academic Search

Ceramides provide a major component of the barrier function of skin. An understanding of barrier organization requires a detailed characterization of ceramide phase behavior and molecular interactions. Toward this end, Fourier transform infrared (FTIR) and differential scanning calorimetry (DSC) studies of ceramide 2 analogues (non-hydroxylated fatty acid N-acyl sphingosines) of specific chain lengths (C14, C16, C18, C20) are presented. In

Hui-Chen Chen; Richard Mendelsohn; Mark E. Rerek; David J. Moore

2000-01-01

352

Determination of olive oil free fatty acid by fourier transform infrared spectroscopy  

Microsoft Academic Search

A new procedure for determining free fatty acids (FFA) in olive oil based on spectroscopic Fourier transform infrared-attenuated\\u000a total reflectance spectroscopy measurements is proposed. The range of FFA contents of samples was extended by adding oleic\\u000a acid to several virgin and pure olive oils, from 0.1 to 2.1%. Calibration models were constructed using partial least-squares\\u000a regression (PLSR). Two wavenumber ranges

Enriqueta Bertran; Marcelo Blanco; Jordi Coello; Hortensia Iturriaga; Santiago Maspoch; Ivan Montoliu

1999-01-01

353

Characterization of the dispersion of chirped fiber Bragg grating through Fourier transform spectrometry method  

Microsoft Academic Search

Introduces a Fourier transform spectrometric method for the precise characterization of dispersion of chirped FBGs(fiber Bragg grating). The measurement system is a fiber Michelson interferometer composed of a broadband EDFA (Erium doped fiber amplifier) light source, a 3db 2×2 fiber coupler, a pair of polarization controllers, a optical attenuator, a fiber filter, an O\\/E converter, A\\/D converter, computer and a

Qingshan Chen; Naiguang Lu; Feng Jiang

2008-01-01

354

Lime kiln source characterization: Lime manufacturing industry Fourier transform infrared spectroscopy. Final report  

SciTech Connect

The purpose of this testing program is to obtain uncontrolled and controlled hydrogen chloride (HCl) and speciated hydrocarbon Hazardous Air Pollutants (HAPs) emissions data from lime production plants to support a national emission standard for hazardous air pollutants (NESHAP). This report presents data from the Fourier Transform Infrared Spectroscopy (FTIR) measurements. FTIR source testing was conducted for the following purposes: Quantify HCl emission levels; and Gather screening (i.e., qualitative) data on other HAP emissions.

Toney, M.L.

1999-07-01

355

Determination of pectin degree of esterification by diffuse reflectance Fourier transform infrared spectroscopy  

Microsoft Academic Search

A diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS) method was developed to measure the degree of esterification (DE) of commercial pectin samples. The relationship between infrared spectroscopy data and titrimetrically determined DE values was investigated. The ester carbonyl band area (C?O) occurring at a mean frequency of 1756 cm?1 had the highest correlation (R2=0.822) with the mean DE of the

Ravin Gnanasambandam; A Proctor

2000-01-01

356

Photoreflectance study of ?-doped semiconductor layers by a fast Fourier transformation  

Microsoft Academic Search

Photoreflectance (PR) spectroscopy has been applied to the investigation of Si ?-doped GaAs, Al0.35Ga0.65As and AlAs layers grown by metal–organic vapor phase epitaxy (MOVPE) on GaAs substrates. The observation of Franz–Keldysh oscillations (FKO) and the application of fast Fourier transform (FFT) has allowed us to determine the internal electric field and, hence, the potential barrier between surface and ?-doped region

M. Nowaczyk; G. Sek; J. Misiewicz; B ?ciana; D. Radziewicz; M. Tlaczala

2000-01-01

357

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

358

A Fourier transform Raman study of water sorption by Kevlar-49  

Microsoft Academic Search

The Fourier transform (FT) Raman spectrum of poly (p-phenylene terephthalamide) (Kevlar-49) is reported. Additional bands, not observed in the conventional Raman spectrum, have been assigned. The changes to the FT-Raman spectrum of Kevlar due to the presence of water have also been examined. As a consequence of the intensity changes to certain Raman modes in this preliminary study, it is

B. H. Stuart

1995-01-01

359

Fourier transform infrared spectroscopic study of intact cells of the nitrogen-fixing bacterium Azospirillum brasilense  

NASA Astrophysics Data System (ADS)

The data of Fourier transform infrared (FTIR) spectroscopic measurements performed on intact cells of the soil nitrogen-fixing bacterium Azospirillum brasilense grown in a standard medium and under the conditions of an increased metal uptake are compared and discussed. The structural FTIR information obtained is considered together with atomic absorption spectrometry (AAS) data on the content of metal cations in the bacterial cells. Some methodological aspects concerning preparation of bacterial cell samples for FTIR measurements are also discussed.

Kamnev, A. A.; Risti?, M.; Antonyuk, L. P.; Chernyshev, A. V.; Ignatov, V. V.

1997-06-01

360

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

361

Infrared small target enhancement via phase spectrum of Quaternion Fourier Transform  

NASA Astrophysics Data System (ADS)

Small target enhancement is one of the crucial stages in infrared small target detection. In this paper, we propose a new method using phase spectrum of Quaternion Fourier Transform to enhance small targets while suppressing backgrounds for infrared images. This is inspired by the property that regularly Gaussian-like shape small targets could be considered as attractively salient signal in infrared images and the location information of such signal is implicitly contained in the phase spectrum from frequency domain. Formally, in the proposed method, we adopt the phase spectrum of Quaternion Fourier Transform instead of using traditional Fourier Transform to enhance the targets since the quaternion provides at most four data channels than only one for the latter, which could be helpful to broad types of background clutters by adding more information. For the construction of the quaternion, we present a second-order directional derivative filter via facet model to compute four second order directional derivative maps from four directions respectively as the four data channels. This filter is used to suppress noises and distinguish the targets and backgrounds into separably different textures so that it would boost the robustness of small target enhancement. In experiments, some typical infrared images with various scenes are tested to validate the effectiveness of the proposed method. The results demonstrate that our method actually has good performance and outperforms several state-of-the-art methods, which can be further used for infrared small target detection and tracking.

Qi, Shengxiang; Ma, Jie; Li, Hang; Zhang, Shuiping; Tian, Jinwen

2014-01-01

362

Efficient packing Fourier-transform approach for ultrahigh resolution isotopic distribution calculations.  

PubMed

Fine isotopic structure patterns resolvable by ultrahigh-resolution mass spectrometers are diagnostic of the elemental composition of moderately large compounds. Despite the proven performance of Fourier transforms algorithms to calculate accurate high resolution isotopic distribution, its application to finer ultrahigh resolving power exhibits limited performance. Fast Fourier transforms algorithm requires sampling the relevant range at equally spaced mass values, but ultrahigh resolution mass spectrum displays highly localized complex patterns (peaks) separated in between by relatively large unstructured intervals. Computational efforts consumed on those uninformative intervals are a waste of resources. A fast and memory efficient procedure is introduced in this paper to calculate the isotopic distribution of a single relatively high-mass molecule at ultrahigh resolution by Fourier transforms approaches. The whole isotopic distribution is packed closer to the monoisotopic peak without distorting the actual scale of the peak fine structure. This packing procedure reduced 8 to 32 times the computation resources in comparison to the same calculation performed without packing. The procedure can be readily implemented in existing software. PMID:20112948

Fernandez-de-Cossio, Jorge

2010-03-01

363

Design Considerations For Fourier Transform Spectrometry In The Near-Infrared And Visible Regions  

NASA Astrophysics Data System (ADS)

Recent advances in the design of Fourier transform spectrometers have now made it possible to extend the spectral range of a single instrument from less than 50 cm-1 to greater than 30,000 cm-1. The most innovative of these instruments allow the sources, beamsplitters and detectors to be changed, and the instrument to be automatically realigned, all within a matter of seconds. As a result, it is possible to measure the electronic and vibrational absorption spectra of samples with the same instrument. In addition, with recent advances in the technique of FT-Raman spectroscopy using near-infrared and visible lasers, it is now possible to measure high resolution Raman spectra with the same interferometer as well. Thus, one Fourier transform instrument can serve to solve many molecular spectroscopy problems. However, extending the range of the interferometer to the shorter wavelengths of the near-infrared, visible and ultraviolet regions places critical demands on the quality of the optical system. To obtain a spectrum at high resolution at high energy, the interferometer moving mirror must travel absolutely perpendicular to the plane of the incident radiation. Any tilt in the moving mirror will degrade the optical resolution, with increasing severity at higher energies. In this presentation, some of the critical aspects of high resolution interferometry at short wavelengths will be discussed. The use of an ultra-stable Fourier transform spectrometer employing a dynamic tilt compensation mechanism will be shown for the measurement of spectra in the near-infrared and visible.

Smith, Matthew J.; Rosenthal, Robert J.

1989-12-01

364

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

2013-08-30

365

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

366

Fourier transform-based design of a patterned piezoelectric energy harvester integrated with an elastoacoustic mirror  

NASA Astrophysics Data System (ADS)

We explore efficient transformation of structure-borne propagating waves into low-power electricity using patterned polymer piezoelectrics integrated with an elastoacoustic mirror configuration. Fourier transform-based spatial optimization of a piezoelectric energy harvester domain weakly coupled to a thin plate housing a continuous elliptical elastoacoustic mirror is presented. Computational modeling and experimental testing are employed to quantify performance enhancement in power generation using the presented approach. Excellent agreement is observed between numerical simulations and experimental measurements. Specifically, dramatic enhancement of the harvested power output is reported by patterning the electrodes of a rectangular polyvinylidene fluoride piezoelectric energy harvester in the elliptical mirror domain.

Carrara, M.; Kulpe, J. A.; Leadenham, S.; Leamy, M. J.; Erturk, A.

2015-01-01

367

Fourier-transform microwave spectroscopy and determination of the three dimensional potential energy surface for Ar–CS  

SciTech Connect

Pure rotational transitions of the Ar–CS van der Waals complex have been observed by Fourier Transform Microwave (FTMW) and FTMW-millimeter wave double resonance spectroscopy. Rotational transitions of v{sub s} = 0, 1, and 2 were able to be observed for normal CS, together with those of C{sup 34}S in v{sub s} = 0, where v{sub s} stands for the quantum number of the CS stretching vibration. The observed transition frequencies were analyzed by a free rotor model Hamiltonian, where rovibrational energies were calculated as dynamical motions of the three nuclei on a three-dimensional potential energy surface, expressed by analytical functions with 57 parameters. Initial values for the potential parameters were obtained by high-level ab initio calculations. Fifteen parameters were adjusted among the 57 parameters to reproduce all the observed transition frequencies with the standard deviation of the fit to be 0.028 MHz.

Niida, Chisato; Nakajima, Masakazu; Endo, Yasuki, E-mail: endo@bunshi.c.u-tokyo.ac.jp [Department of Basic Science, Graduate School of Arts and Sciences, The University of Tokyo, Komaba 3-8-1, Meguro-ku, Tokyo 153-8902 (Japan)] [Department of Basic Science, Graduate School of Arts and Sciences, The University of Tokyo, Komaba 3-8-1, Meguro-ku, Tokyo 153-8902 (Japan); Sumiyoshi, Yoshihiro [Division of Pure and Applied Science, Faculty of Science and Technology, Gunma University, Aramaki 4-2, Maebashi, Gunma 371-8510 (Japan)] [Division of Pure and Applied Science, Faculty of Science and Technology, Gunma University, Aramaki 4-2, Maebashi, Gunma 371-8510 (Japan); Ohshima, Yasuhiro [Department of Photo-Molecular Science, Institute for Molecular Science, Okazaki 444-8585 (Japan)] [Department of Photo-Molecular Science, Institute for Molecular Science, Okazaki 444-8585 (Japan); Kohguchi, Hiroshi [Department of Chemistry, Graduate School of Science, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima 739-8526 (Japan)] [Department of Chemistry, Graduate School of Science, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima 739-8526 (Japan)

2014-03-14

368

Fourier-transform microwave spectroscopy and determination of the three dimensional potential energy surface for Ar-CS.  

PubMed

Pure rotational transitions of the Ar-CS van der Waals complex have been observed by Fourier Transform Microwave (FTMW) and FTMW-millimeter wave double resonance spectroscopy. Rotational transitions of v(s) = 0, 1, and 2 were able to be observed for normal CS, together with those of C(34)S in v(s) = 0, where vs stands for the quantum number of the CS stretching vibration. The observed transition frequencies were analyzed by a free rotor model Hamiltonian, where rovibrational energies were calculated as dynamical motions of the three nuclei on a three-dimensional potential energy surface, expressed by analytical functions with 57 parameters. Initial values for the potential parameters were obtained by high-level ab initio calculations. Fifteen parameters were adjusted among the 57 parameters to reproduce all the observed transition frequencies with the standard deviation of the fit to be 0.028 MHz. PMID:24628172

Niida, Chisato; Nakajima, Masakazu; Sumiyoshi, Yoshihiro; Ohshima, Yasuhiro; Kohguchi, Hiroshi; Endo, Yasuki

2014-03-14

369

ENGR 203 Electrical Fundamentals III Catalog Description: Laplace transforms, Fourier series, Bode plots, and their application to  

E-print Network

to circuit analysis · The transfer function · Time convolution · Introduction to Fourier series · Bode plotsENGR 203 ­ Electrical Fundamentals III Catalog Description: Laplace transforms, Fourier series, Bode plots, and their application to circuit analysis. Credits: 3 Terms Offered: Fall, Spring

370

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

371

Direct and quantitative broadband absorptance spectroscopy on small objects using Fourier transform infrared spectrometer and bilayer cantilever probes  

E-print Network

A measurement platform is introduced that combines a bilayer cantilever probe with a Fourier transform infrared spectrometer to measure absolute spectral absorptance between wavelengths of 3??m and 18??m directly and ...

Hsu, Wei-Chun

372

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 ...

373

Identification and characterization of salmonella serotypes using DNA spectral characteristics by fourier transform infrared (FT-IR) spectroscopy  

Technology Transfer Automated Retrieval System (TEKTRAN)

Analysis of DNA samples of Salmonella serotypes (Salmonella Typhimurium, Salmonella Enteritidis, Salmonella Infantis, Salmonella Heidelberg and Salmonella Kentucky) were performed using Fourier transform infrared spectroscopy (FT-IR) spectrometer by placing directly in contact with a diamond attenua...

374

A Fourier Transform Method for Vsin i Estimations under Nonlinear Limb-darkening Laws  

NASA Astrophysics Data System (ADS)

Star rotation offers us a large horizon for the study of many important physical issues pertaining to stellar evolution. Currently, four methods are widely used to infer rotation velocities, namely those related to line width calibrations, on the fitting of synthetic spectra, interferometry, and on Fourier transforms (FTs) of line profiles. Almost all of the estimations of stellar projected rotation velocities using the Fourier method in the literature have been addressed with the use of linear limb-darkening (LD) approximations during the evaluation of rotation profiles and their cosine FTs, which in certain cases, lead to discrepant velocity estimates. In this work, we introduce new mathematical expressions of rotation profiles and their Fourier cosine transforms assuming three nonlinear LD laws—quadratic, square-root, and logarithmic—and study their applications with and without gravity-darkening (GD) and geometrical flattening (GF) effects. Through an analysis of He I models in the visible range accounting for both limb and GD, we find out that, for classical models without rotationally driven effects, all the Vsin i values are too close to each other. On the other hand, taking into account GD and GF, the Vsin i obtained with the linear law result in Vsin i values that are systematically smaller than those obtained with the other laws. As a rule of thumb, we apply these expressions to the FT method to evaluate the projected rotation velocity of the emission B-type star Achernar (? Eri).

Levenhagen, R. S.

2014-12-01

375

C. R. WORTHINGTON 783 Fourier transform of t(r) is T(R) and, using Cartesian  

E-print Network

C. R. WORTHINGTON 783 Fourier transform of t(r) is T(R) and, using Cartesian coordinates, T(X, Y, Z)= T(X, Y)T(Z). This is a simplification in the computation of the diffraction intensity I(~:, l). One can write, after omitting the weight factors, the Fourier transform T(X, Y) as T(X, Y) = sinc ¢r

Rossmann, Michael G.

376

Introduction to Quantum Simulation  

NASA Technical Reports Server (NTRS)

This viewgraph presentation addresses the problem of efficiently simulating the evolution of a quantum system. The contents include: 1) Quantum Simulation; 2) Extracting Answers from Quantum Simulations; 3) Quantum Fourier Transform; 4) Eigenvalue Estimation; 5) Fermionic Simulations.

Williams, Colin P.

2005-01-01

377

Digital watermarking algorithm research of color images based on quaternion Fourier transform  

NASA Astrophysics Data System (ADS)

A watermarking algorithm of color images based on the quaternion Fourier Transform (QFFT) and improved quantization index algorithm (QIM) is proposed in this paper. The original image is transformed by QFFT, the watermark image is processed by compression and quantization coding, and then the processed watermark image is embedded into the components of the transformed original image. It achieves embedding and blind extraction of the watermark image. The experimental results show that the watermarking algorithm based on the improved QIM algorithm with distortion compensation achieves a good tradeoff between invisibility and robustness, and better robustness for the attacks of Gaussian noises, salt and pepper noises, JPEG compression, cropping, filtering and image enhancement than the traditional QIM algorithm.

An, Mali; Wang, Weijiang; Zhao, Zhen

2013-10-01

378

Three-dimensional adaptive coordinate transformations for the Fourier modal method.  

PubMed

The concepts of adaptive coordinates and adaptive spatial resolution have proved to be a valuable tool to improve the convergence characteristics of the Fourier Modal Method (FMM), especially for metallo-dielectric systems. Yet, only two-dimensional adaptive coordinates were used so far. This paper presents the first systematic construction of three-dimensional adaptive coordinate and adaptive spatial resolution transformations in the context of the FMM. For that, the construction of a three-dimensional mesh for a periodic system consisting of two layers of mutually rotated, metallic crosses is discussed. The main impact of this method is that it can be used with any classic FMM code that is able to solve the large FMM eigenproblem. Since the transformation starts and ends in a Cartesian mesh, only the transformed material tensors need to be computed and entered into an existing FMM code. PMID:24515140

Küchenmeister, Jens

2014-01-27

379

Image encryption based on the multiple-parameter discrete fractional Fourier transform and chaos function  

NASA Astrophysics Data System (ADS)

In recent years, the chaos-based cryptographic algorithms have suggested some new and efficient ways to develop secure image encryption techniques. In this paper, we propose a new approach for image encryption based on the multiple-parameter discrete fractional Fourier transform and chaotic logistic maps in order to meet the requirements of the secure image transmission. In the proposed image encryption scheme, the image is encrypted by juxtaposition of sections of the image in the multiple-parameter discrete fractional Fourier domains and the alignment of sections is determined by chaotic logistic maps. This method does not require the use of phase keys. The new method has been compared with several existing methods and shows comparable or superior robustness to blind decryption.

Lang, Jun; Tao, Ran; Wang, Yue

2010-05-01

380

Application of Fourier transform infrared spectroscopy to silica diagenesis: The opal-A to opal-CT transformation  

SciTech Connect

An important goal in silica diagenesis research is to understand the kinetics of opal transformation from noncrystalline opal-A to the disordered silica polymorph opal-CT. Because the conventional technique for monitoring the transformation, powder X-ray diffraction (XRD), is applicable only to phases with long-range order, the authors used Fourier transform infrared spectroscopy (FTIR) to monitor the transformation. They applied this technique, combined with XRD and TEM, to experimental run products and natural opals from the Monterey Formation and from siliceous deposits in the western Pacific Ocean. Using a ratio of two infrared absorption intensities ({omega} = I{sub 472 cm{sup {minus}1}}/I{sub 500 cm{sup {minus}1}}), the relative proportions of opal-A and opal-CT can be determined. The progress of the transformation is marked by changes in slope of {omega} vs. depth or time when a sufficient stratigraphic profile is available. There are three stages in the opal-A to opal-CT reaction: (1) opal-A dissolution; (2) opal-CT precipitation, whose end point is marked by completion of opal-A dissolution; and (3) opal-CT ordering, during which tridymite stacking is eliminated in favor of crystobalite stacking.

Rice, S.B.; Freund, H.; Huang, W.L.; Clouse, J.A. [Exxon Production Research Co., Houston, TX (United States); Isaacs, C.M. [Geological Survey, Menlo Park, CA (United States)

1995-10-02

381

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

382

Efficient method for localized functions using domain transformation and Fourier sine series  

E-print Network

An efficient approach to handle localized states by using spectral methods (SM) in one and three dimensions is presented. The method consists of transformation of the infinite domain to the bounded domain in $(0, \\pi)$ and using the Fourier sine series as a set of basis functions for the SM. It is shown that with an appropriate choice of transformation functions, this method manages to preserve the good properties of original SMs; more precisely, superb computational efficiency when high level of accuracy is necessary. This is made possible by analytically exploiting the properties of the transformation function and the Fourier sine series. An especially important property of this approach is the possibility of calculating the Hartree energy very efficiently. This is done by exploiting the positive properties of the sine series as a basis set and conducting an extinctive part of the calculations analytically. We illustrate the efficiency of this method and implement it to solve the Poisson's and Helmholtz equations in both one and three dimensions. The efficiency of the method is verified through a comparison to recently published results for both one and three dimensional problems.

Raka Jovanovic; Sabre Kais; Fahhad H. Alharbi

2014-02-06

383

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

2012-01-01

384

Identification of Early Biomarkers during Acetaminophen-Induced Hepatotoxicity by Fourier Transform Infrared Microspectroscopy  

PubMed Central

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

Deobagkar-Lele, Mukta; Rakshit, Srabanti; Kumar B. N., Vinay; Umapathy, Siva; Nandi, Dipankar

2012-01-01

385

Slit Function Measurement of An Imaging Spectrograph Using Fourier Transform Techniques  

NASA Technical Reports Server (NTRS)

Knowledge of a spectrograph slit function is necessary to interpret the unresolved lines in an observed spectrum. A theoretical slit function can be calculated from the sizes of the entrance slit, the detector aperture when it functions as an exit slit, the dispersion characteristic of the disperser, and the point spread function of the spectrograph. A measured slit function is preferred to the theoretical one for the correct interpretation of the spectral data. In a scanning spectrometer with a single exit slit, the slit function is easily measured. In a fixed grating/or disperser spectrograph, illuminating the entrance slit with a near monochromatic light from a pre-monochrmator or a tunable laser and varying the wavelength of the incident light can measure the slit function. Even though the latter technique had been used successfully for the slit function measurements, it had been very laborious and it would be prohibitive to an imaging spectrograph or a multi-object spectrograph that has a large field of view. We explore an alternative technique that is manageable for the measurements. In the proposed technique, the imaging spectrograph is used as a detector of a Fourier transform spectrometer. This method can be applied not only to an IR spectrograph but also has a potential to a visible/UV spectrograph including a wedge filter spectrograph. This technique will require a blackbody source of known temperature and a bolometer to characterize the interferometer part of the Fourier Transform spectrometer. This pa?er will describe the alternative slit function measurement technique using a Fourier transform spectrometer.

Park, Hongwoo; Swimyard, Bruce; Jakobsen, Peter; Moseley, Harvey; Greenhouse, Matthew

2004-01-01

386

Determination of phospholipid content of intramuscular fat by Fourier Transform Infrared spectroscopy.  

PubMed

A method has been developed to determine the phospholipid content in fat extract with FTIR (Fourier Transform Infrared). l-?-Phosphatidylcholine from egg yolk in hexane solution was used as a reference for band identification at different concentrations. Phosphate bands were determined at different wavenumbers as described in the literature. A dilution series was made from meat extract and from 1-?-phosphatidylcholine. A linear calibration curve was obtained between the FTIR-results and the Iatroscan results, which were used as a reference. The band between 1282 cm(-1) and 1020 cm(-1) can be used for determination of phospholipid content. PMID:22060199

Villé, H; Maes, G; De Schrijver, R; Spincemaille, G; Rombouts, G; Geers, R

1995-01-01

387

Characterization of chemically amplified resist for X-ray lithography by Fourier transform infrared spectroscopy  

Microsoft Academic Search

SU-8 resist was characterized for X-ray lithography from a plasma focus\\u000a source by studying its cross-linking process using Fourier transform\\u000a infrared (FT-IR) spectroscopy. The cross-linking process of the resist\\u000a during post-exposure bake (PEB) was accurately monitored using the\\u000a infrared absorption peaks at 862, 914, and 1128 cm(-1). Results showed\\u000a that the cross-linking of SU-8 was effectively completed at the exposure

T. L. Tan; D. Wong; P Lee; R. S. Rawat; S. Springham; A. Patran

2006-01-01

388

Design and application of the snapshot hyperspectral imaging Fourier transform (SHIFT) spectropolarimeter for fluorescence imaging  

NASA Astrophysics Data System (ADS)

We present a novel and inexpensive Stokes imaging spectropolarimeter based on the Snapshot Hyperspectral Imaging Fourier Transform (SHIFT) spectrometer. A rotating quarter wave plate and stationary linear polarizer placed in front of the SHIFT spectrometer enables us to reconstruct an object's spectra and Stokes parameters in the visible spectrum. Measurements are stored in the form of four-dimensional (4D) Stokes datacubes containing the object's spatial, spectral, and polarization information. We discuss calibration methods, review design considerations, and present preliminary results from proof-of-concept experiments.

Chan, Victoria C.; Kudenov, Michael; Liang, Chen; Zhou, Pixuan; Dereniak, Eustace

2014-03-01

389

Application of numerical Fourier transformation on measurements made on board rotating spacecraft  

NASA Astrophysics Data System (ADS)

Use of a Fast Fourier Transform algorithm to perform digital evaluation of signals from spacecraft featuring spin modulation and nutational effects is described. The case of a rotating spacecraft without nutation is modeled, with account taken of demodulation performed simultaneously with respect to amplitude and phase. Applying the demodulation technique twice removes the nutational effects. Assumptions are made that the spectral functions do not vary as fast as the spin modulation, and the signal variance independent of spacecraft rotation occurs at a rate significantly less than the spin rate. A demodulation example is given for a signal received from a probe on the Porcupine 2 rocket.

Grabowski, R.; Boesch, B.; Wolf, H.

390

Multicomponent FM demodulation of speech based on the short-time Fourier transform (STFT) phase  

NASA Astrophysics Data System (ADS)

Speech is a signal which is produced as a combination of frication and a quasi periodic train of glottal pulses excites the vocal tract and causes it to resonate. Information is encoded on the signal as the vocal tract changes configuration, resulting in a rapid change of the resonant frequencies. We develop methods, based on differentiation of the short time Fourier transform (STFT) phase, which effectively demodulates the speech signal and produces accurate, high resolution time-frequency estimates of both the resonances and the signal excitation. The method effectively condenses the STFT surface along curves representing the instantaneous frequencies of the vocal tract resonances and the channel group delay function.

Nelson, Douglas J.

2001-03-01

391

Fourier transform C-13 NMR analysis of some free and potassium-ion complexed antibiotics.  

NASA Technical Reports Server (NTRS)

Fourier transforms of the noise-decoupled, natural abundance C-13 NMR free induction decays of the cyclic antibiotic valinomycin and its potassium-ion complex have been obtained at 25.2 MHz. Comparisons are made with C-13 NMR spectra taken at 22.6 MHz of the cyclic antibiotic nonactin and the synthetic polyether dicyclohexyl-18-crown-6 and their potassium complexes. The results obtained suggest that conformational rearrangements of the molecule as a whole can compete with direct interactions between carbons and the potassium ion in determining C-13 chemical shift differences between the free and complexed species.

Ohnishi, M.; Fedarko, M.-C.; Baldeschwieler, J. D.; Johnson, L. F.

1972-01-01

392

Analysis of stacking faults in gallium nitride by Fourier transform of high-resolution images  

NASA Astrophysics Data System (ADS)

We present results of studying stacking faults (SFs) in gallium nitride (GaN) with the aid of Fourier transform of high-resolution transmission electron microscopy (HRTEM) images. Using this method, it is possible both to determine the SF type and to directly measure the corresponding displacement vector. This allowed us to explain the peculiarities of the contrast of HRTEM of structures with high SF density (above 106 cm-1). It is established that the displacement vector component in the (0001) plane in these structures can significantly differ from the expected value of that is typical of single SFs.

Kirilenko, D. A.; Sitnikova, A. A.; Kremleva, A. V.; Mynbaeva, M. G.; Nikolaev, V. I.

2014-12-01

393

Measurements of solar magnetic fields by Fourier transform techniques. I - Unsaturated lines  

NASA Technical Reports Server (NTRS)

If the basic profile shapes of the normal Zeeman triplet do not have zeros in their Fourier transform, the magnetic field splitting can be determined independent of the profile shape. When the ratio of the splitting of the components is greater than the intrinsic FWHM of the component profiles, the magnetic splitting can be determined with significantly greater accuracy than the measurement accuracy of the original profile. For Gaussian shaped components and a ratio of magnetic splitting to FWHM of 1.5, the noise reduction factor is 25.

Title, A. M.; Tarbell, T. D.

1975-01-01

394

Fourier transform Raman spectroscopic studies of a novel wood pulp bleaching system  

NASA Astrophysics Data System (ADS)

The use of near-infrared (NIR) Fourier transform (FT) Raman spectroscopy for the study of lignocellulosic materials is discussed. An application utilizing NIR FT-Raman spectroscopy to study a novel chlorine-free process for the bleaching of wood pulps is presented in detail. The new process, still under development, entails the oxidation of residual lignin in wood pulps by vanadium-substituted polyoxometalates, and reoxidation of the reduced polyoxometalates by chlorine-free oxidants such as air, dioxygen, peroxides or ozone. Results from FT-Raman measurements of polyoxometalate-treated pulps are compared with those from chemical, spectroscopic and optical techniques commonly used in the pulp and paper industry.

Weinstock, Ira A.; Atalla, Rajai H.; Agarwal, Umesh P.; Minor, James L.; Petty, Chris

1993-06-01

395

Light field camera as a Fourier transform spectrometer sensor: instrument characterization and passive spectral ranging.  

PubMed

This paper presents a concept using field cameras in combination with Fourier transform spectrometers. The device can produce five-dimensional (position-angle-spectra) data cubes. This can lead to accurate measurements in both spectrum and distance and allows a thorough characterization of the interferometer, as well as adds passive ranging information to hyperspectral images. Shear and tilt fringes are simultaneously observed in a fixed optical path difference interferometer, and a passive spectral ranging demonstration is done in both absorption and emission for the 500-900 nm spectral bands. PMID:25089997

Côté, Alex; Levasseur, Simon; Boudreau, Sylvain; Genest, Jérôme

2014-07-01

396

An iterative algorithm for cell segmentation using short-time Fourier transform.  

PubMed

In this paper, an iterative cell image segmentation algorithm using short-time Fourier transform magnitude vectors as class features is presented. The cluster centroids of the magnitude vectors are obtained by the K-means clustering method and used as representative class features. The initial image segmentation classifies only those image pixels whose surrounding closely matches a class centroid. The subsequent procedure iteratively classifies the remaining image pixels by combining their spatial distance from the regions already segmented and the similarities between their corresponding magnitude vectors and the cluster centroids. Experimental results of the proposed algorithm for segmenting real cell images are provided. PMID:8972098

Wu, H S; Barba, J; Gil, J

1996-11-01

397

On-line emissions monitoring of chlorobenzene incineration using Fourier transform infrared spectroscopy  

SciTech Connect

Incineration of chlorobenzene in a small laboratory incinerator was monitored by using Fourier transform infrared spectroscopy (FTIR) coupled with a heated long-path cell (LPC) to analyze and quantify flue gas emissions in near real time. The effects of operating conditions under stable and decreasing incineration temperatures on the destruction of chlorobenzene were studied. The results from the decreasing temperature experiments were found to be consistent with those from experiments at stable temperatures. This finding demonstrates that the FTIR/LPC, as a continuous emissions monitor, can effectively detect dynamic changes in the incinerator emissions and can contribute significantly to the safety of incinerators.

Mao, Zhuoxiong; McIntosh, M.J.; Demirgian, J.C.

1992-01-01

398

On-line emissions monitoring of chlorobenzene incineration using Fourier transform infrared spectroscopy  

SciTech Connect

Incineration of chlorobenzene in a small laboratory incinerator was monitored by using Fourier transform infrared spectroscopy (FTIR) coupled with a heated long-path cell (LPC) to analyze and quantify flue gas emissions in near real time. The effects of operating conditions under stable and decreasing incineration temperatures on the destruction of chlorobenzene were studied. The results from the decreasing temperature experiments were found to be consistent with those from experiments at stable temperatures. This finding demonstrates that the FTIR/LPC, as a continuous emissions monitor, can effectively detect dynamic changes in the incinerator emissions and can contribute significantly to the safety of incinerators.

Mao, Zhuoxiong; McIntosh, M.J.; Demirgian, J.C.

1992-06-01

399

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 PMID:1378614

Solouki, T; Russell, D H

1992-01-01

400

In situ optical histochemistry of human artery using near infrared Fourier transform Raman spectroscopy.  

PubMed Central

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 over 1.5 mm below the irradiated surface of the tissue, possibly allowing extraction of three-dimensional information about the histology of atherosclerotic plaques. We propose that this technique may be utilized for in situ optical histochemical analysis of atherosclerosis in particular and human disease in general. PMID:1565640

Baraga, J J; Feld, M S; Rava, R P

1992-01-01

401

Characterization of naturally-occurring and modified fullerenes by Fourier transform mass spectrometry  

NASA Astrophysics Data System (ADS)

Fourier transform mass spectrometry (FTMS) employing both laser desorption/ionization and thermal desorption/electron ionization is useful for the detection and structural characterization of fullerenes and chemically-modified fullerenes. Examination of a carbon-rich shungite rock sample from Russia by transmission electron microscopy and FTMS provided evidence of naturally-occurring fullerenes. Ion-molecule reactions can be studied with FTMS to investigate the electron affinities of modified fullerenes. By monitoring charge exchange reactions, the electron affinities of C60Fx (x=44,46) and C70Fy (y=52,54) were found to be substantially higher than the values for the parent fullerenes.

Hettich, Robert L.; Jin, Changming; Compton, Robert N.; Buseck, Peter R.; Tsipursky, Semeon J.

1993-10-01

402

Fourier transform infrared reflection absorption spectrometry and electron spectroscopy for chemical analysis for surface analysis  

SciTech Connect

The combination of electron spectroscopy for chemical analysis (ESCA) and Fourier transform was tested for usefulness in surface analysis. The surface sensitivity of IR was increased by the use of IR reflection absorption spectrometry (IR-RAS) coupled with FT-IR. Examination of oxide layers of thickness of about 100 A formed on copper plates with both techniques together with ellipsometry is described in detail. Growth of oxide layers of different composition corresponding to different heating temperatures was manifested with the analysis. The result verifies effective combination of these two complementary techniques. 14 figures, 1 table.

Ishitani, A.; Ishida, H.; Soeda, F.; Nagasawa, Y.

1982-04-01

403

Improving imaging resolution of shaking targets by Fourier-transform ghost diffraction  

NASA Astrophysics Data System (ADS)

For conventional imaging, shaking of the imaging system or the target leads to the degradation of imaging resolution. The influence of the target's shaking to Fourier-transform ghost diffraction (FGD) is investigated and phase-retrieval method is used to recover the target's imaging. The analytical results, which are backed up by numerical simulation and experiments, demonstrate that the quiver of target has no effect on the resolution of FGD and high-resolution imaging can be always achieved by phase-retrieval method from FGD patterns. This approach can be applied in high-precision imaging systems, to overcome the influence of the system's shaking to imaging resolution.

Zhang, Cong; Gong, Wenlin; Han, Shensheng

2013-01-01

404

ESCA (Electron Spectroscopy for Chemical Analysis) and FTIR (Fourier Transform Infrared Spectroscopy) studies of bituminous coal  

SciTech Connect

Bituminous coal from the Illinois No. 6, Upper Freeport, Pittsburgh and Kentucky No. 9 seams were examined by Electron Spectroscopy for Chemical Analysis (ESCA) and Fourier Transform Infrared Spectroscopy (FTIR). These coals were stored under various conditions (air, N{sub 2}, mine water) and received in forms progressing from raw to ash - removed coal, (raw, milled, processed). ESCA was utilized to determine surface elemental composition and functional groups with particular attention given to C, O, N and S. Sulfur and oxidized coal models have been examined to determine the sulfur and carbon species present at the surface. FTIR has been used to correlate functional group assignments with the ESCA results.

Weitzsacker, C.L.; Schmidt, J.J.; Gardella, J.A. Jr. (Univ. of Buffalo, NY (USA))

1989-01-01

405

Set-up for broadband Fourier-transform multidimensional electronic spectroscopy.  

PubMed

We present a compact passively phase-stabilized ultra-broadband 2D Fourier transform setup. A gas (argon)-filled hollow core fiber pumped by an amplified Ti:Al2O3 laser is used as a light source providing spectral range spanning from 420 to 900 nm. Sub-10-fs pulses were obtained using a deformable mirror-based pulse shaper. We probe the nonlinear response of Rhodamine 101 using 90 nm bandwidth and resolve vibrational coherences of 150 fs period in the ground state. PMID:25680035

Al Haddad, A; Chauvet, A; Ojeda, J; Arrell, C; van Mourik, F; Auböck, G; Chergui, M

2015-02-01

406

Fourier transform photoacoustic kinetic spectroscopy of solid surfaces. Annual progress report, April 1-December 10, 1980  

SciTech Connect

A description of visible Fourier transform photoacoustic spectroscopy (PAS) has been published in two places. Application of PAS to a zirconium phosphate inorganic system has also been described. The use of visible synchrotron radiation in quantitative high frequency PAS has been attempted, and a theoretical modeling of such experiments is nearing completion. A Nicolet FTIR spectrometer is being used to perform mid-infrared PA spectroscopy on carbon samples with a view to determining the best means of ratioing out variations with wavelength in infrared source intensity.

Eyring, E.M.

1980-12-01

407

Graphics processing unit accelerated non-uniform fast Fourier transform for ultrahigh-speed, real-time Fourier-domain OCT  

PubMed Central

We implemented fast Gaussian gridding (FGG)-based non-uniform fast Fourier transform (NUFFT) on the graphics processing unit (GPU) architecture for ultrahigh-speed, real-time Fourier-domain optical coherence tomography (FD-OCT). The Vandermonde matrix-based non-uniform discrete Fourier transform (NUDFT) as well as the linear/cubic interpolation with fast Fourier transform (InFFT) methods are also implemented on GPU to compare their performance in terms of image quality and processing speed. The GPU accelerated InFFT/NUDFT/NUFFT methods are applied to process both the standard half-range FD-OCT and complex full-range FD-OCT (C-FD-OCT). GPU-NUFFT provides an accurate approximation to GPU-NUDFT in terms of image quality, but offers >10 times higher processing speed. Compared with the GPU-InFFT methods, GPU-NUFFT has improved sensitivity roll-off, higher local signal-to-noise ratio and immunity to side-lobe artifacts caused by the interpolation error. Using a high speed CMOS line-scan camera, we demonstrated the real-time processing and display of GPU-NUFFT-based C-FD-OCT at a camera-limited rate of 122 k line/s (1024 pixel/A-scan). PMID:21164690

Zhang, Kang; Kang, Jin U.

2010-01-01

408

Reconstruction of piecewise homogeneous images from partial knowledge of their Fourier Transform  

NASA Astrophysics Data System (ADS)

Fourier synthesis (FS) inverse problem consists in reconstructing a multi-variable function from the measured data which correspond to partial and uncertain knowledge of its Fourier Transform (FT). By partial knowledge we mean either partial support and/or the knowledge of only the module and by uncertain we mean both uncertainty of the model and noisy data. This inverse problem arises in many applications such as : optical imaging, radio astronomy, magnetic resonance imaging (MRI) and diffraction scattering (ultrasounds or microwave imaging). Most classical methods of inversion are based on interpolation of the data and fast inverse FT. But when the data do not fill uniformly the Fourier domain or when the phase of the signal is lacking as in optical interferometry, the results obtained by such methods are not satisfactory, because these inverse problems are ill-posed. The Bayesian estimation approach, via an appropriate modeling of the unknown functions gives the possibility of compensating the lack of information in the data, thus giving satisfactory results. In this paper we study the case where the observations are a part of the FT modulus of objects which are composed of a few number of homogeneous materials. To model such objects we use a Hierarchical Hidden Markov Modeling (HMM) and propose a Bayesian inversion method using appropriate Markov Chain Monte Carlo (MCMC) algorithms.

Féron, Olivier; Chama, Zouaoui; Mohammad-Djafari, Ali

2004-11-01

409

Testing and data path redesign of a high speed, 16-point Winograd Fourier transform processor  

NASA Astrophysics Data System (ADS)

A prototype 16-point, 70 MHz Fourier transform processor using 1.2 micron minimum feature sizes was tested using a Tektronix DAS 9200, digital analysis system. The results showed that it is possible to operate an Air Force Institute of Technology (AFIT) WFT16 chip at 70 MHz. The results also showed a great deal of variation among the individual packaged chips. Using the WFT16's built in testing circuitry, portions of the main data and control circuitry were tested. The AFIT XROM address generator and control circuitry proved to be the most reliable chip subsection, followed by the arithmetic and register control system. The parallel-in serial-out input data register was also tested and showed consistent results even though the results were not as expected. The variation among chips was shown when attempts at trivial transforms were done. The attempted transforms consisted of dc data values of zero and minus one. Two of 16 tested chips showed correct transform values, but for only a limited, nonrepeated sequence. In later testing, two chips were found that gave repeatable results which closely approximated the expected results for both trivial and nontrivial transform attempts. Test procedures and input to output relationships were determine to aid further testing of the AFIT WFT16 circuit.

Pavick, Steven W.

1989-12-01

410

Universal Quantum Circuit of Near-Trivial Transformations  

E-print Network

Any unitary transformation can be decomposed into a product of a group of near-trivial transformations. We investigate in details the construction of universal quantum circuit of near trivial transformations. We first construct two universal quantum circuits which can implement any single-qubit rotation $R_y(\\theta)$ and $R_z(\\theta)$ within any given precision, and then we construct universal quantum circuit implementing any single-qubit transformation within any given precision. Finally, a universal quantum circuit implementing any $n$-qubit near-trivial transformation is constructed using the universal quantum circuits of $R_y(\\theta)$ and $R_z(\\theta)$. In the universal quantum circuit presented, each quantum transformation is encoded to a bit string which is used as ancillary inputs. The output of the circuit consists of the related bit string and the result of near-trivial transformation. Our result may be useful for the design of universal quantum computer in the future.

Min Liang; Li Yang

2011-05-09

411

Cavity QED implementation of the discrete quantum Fourier transform  

E-print Network

interacts with only one mode, either resonantly or dispersively as the situation requires. The authors gratefully acknowledge the support from the Air Force Research Laboratory ~Rome, New York!, DARPA- QuIST, TAMU Telecommunication and Informatics Task...

Scully, Marlan O.; Zubairy, M. Suhail

2002-01-01

412

Identification of Earthquake Induced Damage Areas Using Fourier Transform and SPOT HRVIR Pan Images  

PubMed Central

A devastating earthquake with a magnitude of Mw 7.4 occurred on the North Anatolian Fault Zone (NAFZ) of Turkey on August 17, 1999 at 00:01:39 UTC (3:01 a.m. local time). The aim of this study is to propose a new approach to automatically identify earthquake induced damage areas which can provide valuable information to support emergency response and recovery assessment procedures. This research was conducted in the Adapazari inner city, covering a 3 × 3 km area, where 11,373 buildings collapsed as a result of the earthquake. SPOT high resolution visible infrared (HRVIR) Pan images obtained before (25 June 1999) and after (4 October 1999) the earthquake were used in the study. Five steps were employed to conduct the research and these are: (i) geometric and radiometric correction of satellite images, (ii) Fast Fourier Transform (FFT) of pre- and post-earthquake images and filtering the images in frequency domain, (iii) generating difference image using Inverse Fast Fourier Transform (IFFT) pre- and post- earthquake images, (iv) application of level slicing to difference image to identify the earthquake-induced damages, (v) accuracy assessment of the method using ground truth obtained from a 1/5,000 scale damage map. The total accuracy obtained in the research is 80.19 %, illustrating that the proposed method can be successfully used to automatically identify earthquake-induced damage areas. PMID:22573966

Sertel, Elif

2009-01-01

413

Chemical fingerprinting of Arabidopsis using Fourier transform infrared (FT-IR) spectroscopic approaches.  

PubMed

Fourier transform infrared (FT-IR) spectroscopy is a fast, sensitive, inexpensive, and nondestructive technique for chemical profiling of plant materials. In this chapter we discuss the instrumental setup, the basic principles of analysis, and the possibilities for and limitations of obtaining qualitative and semiquantitative information by FT-IR spectroscopy. We provide detailed protocols for four fully customizable techniques: (1) Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS): a sensitive and high-throughput technique for powders; (2) attenuated total reflectance (ATR) spectroscopy: a technique that requires no sample preparation and can be used for solid samples as well as for cell cultures; (3) microspectroscopy using a single element (SE) detector: a technique used for analyzing sections at low spatial resolution; and (4) microspectroscopy using a focal plane array (FPA) detector: a technique for rapid chemical profiling of plant sections at cellular resolution. Sample preparation, measurement, and data analysis steps are listed for each of the techniques to help the user collect the best quality spectra and prepare them for subsequent multivariate analysis. PMID:24057375

Gorzsás, András; Sundberg, Björn

2014-01-01

414

Fourier-transform spectroscopy combined with a 5-fs broadband pulse for multispectral nonlinear microscopy  

NASA Astrophysics Data System (ADS)

We propose a technique for distinguishing the origin of a four-wave mixing (FWM) signal. This technique is based on nonlinear Fourier-transform spectroscopy (FTS) combined with the use of a broadband pulse. We theoretically analyze FWM-FTS and show that the response function in FWM is obtained from the FWM power spectrum calculated by the Fourier transform of an interferometric autocorrelation signal. When a broadband pulse is employed as an excitation light source, the FWM power spectrum shows not only Raman resonance but also two-photon electronic resonance. By comparing the FWM power spectrum of a resonant sample with that of a nonresonant reference sample, the origin of FWM is identified. By employing theoretical analysis, we experimentally demonstrate FWM-FTS using a 5-fs broadband pulse. By combining the use of a 5-fs pulse with nonlinear FTS based on two-photon excited fluorescence, we also successfully measured a two-photon excitation spectrum with a bandwidth of 300 nm.

Isobe, Keisuke; Suda, Akira; Tanaka, Masahiro; Kannari, Fumihiko; Kawano, Hiroyuki; Mizuno, Hideaki; Miyawaki, Atsushi; Midorikawa, Katsumi

2008-06-01

415

Geometric phase analysis based on the windowed Fourier transform for the deformation field measurement  

NASA Astrophysics Data System (ADS)

The geometric phase analysis (GPA), an important image-based deformation measurement method, has been used at both micro- and nano-scale. However, when a deformed image has apparent distortion, non-ignorable error in the obtained deformation field could occur by using this method. In this paper, the geometric phase analysis based on the windowed Fourier transform (WFT) is proposed to solve the above-mentioned issue, defined as the WFT-GPA method. In WFT-GPA, instead of the Fourier transform (FT), the WFT is utilized to extract the phase field block by block, and therefore more accurate local phase information can be acquired. The simulation tests, which include detailed discussion of influence factors for measurement accuracy such as window size and image noise, are conducted with digital deformed grids. The results verify that the WFT-GPA method not only keeps all advantages of traditional GPA method, but also owns a better accuracy for deformation measurement. Finally, the WFT-GPA method is applied to measure the machining distortion incurred in soft ultraviolet nanoimprint lithography (UV-NIL) process. The successful measurement shows the feasibility of this method and offers a full-field way for characterizing the replication quality of UV-NIL process.

Dai, Xianglu; Xie, Huimin; Wang, Qinghua

2014-06-01

416

An Intelligent Dynamic Alignment System for Interferometer of Fourier Transform Spectrometer  

NASA Astrophysics Data System (ADS)

An intelligent dynamic alignment system for a Michelson interferometer which is applied to a Mid-infrared band Fourier transform spectrometer (FTS) is presented. Three photodiodes are used to detect the tilt of moving mirror opposite to fixed mirror with the assistance of the interfered signal of a reference He-Ne laser. This technique is based on detecting the phase difference of laser signal between every two diodes in two perpendicular directions. And four magnetic actuators behind the mounting brace of fixed mirror are used to change the pose of fixed mirror. The system is controlled by a digital signal processor (DSP) in real-time. A feedback algorithm is used to tilt fixed mirror following the action of moving mirror so as to keep both mirror planes in perpendicular. Experiment result shows that the relative tilt between two reflecting mirrors can be restricted in a range no more than ±1.5×10-6rad. This system is effective and reliable to be applied to scanning interferometer of Fourier transform spectrometer.

Yang, Kun; Zeng, Libo

417

Miniature, Low-Power, Waveguide Based Infrared Fourier Transform Spectrometer for Spacecraft Remote Sensing  

NASA Technical Reports Server (NTRS)

Fourier transform spectrometers have a venerable heritage as flight instruments. However, obtaining an accurate spectrum exacts a penalty in instrument mass and power requirements. Recent advances in a broad class of non-scanning Fourier transform spectrometer (FTS) devices, generally called spatial heterodyne spectrometers, offer distinct advantages as flight optimized systems. We are developing a miniaturized system that employs photonics lightwave circuit principles and functions as an FTS operating in the 7-14 micrometer spectral region. The inteferogram is constructed from an ensemble of Mach-Zehnder interferometers with path length differences calibrated to mimic scan mirror sample positions of a classic Michelson type FTS. One potential long-term application of this technology in low cost planetary missions is the concept of a self-contained sensor system. We are developing a systems architecture concept for wide area in situ and remote monitoring of characteristic properties that are of scientific interest. The system will be based on wavelength- and resolution-independent spectroscopic sensors for studying atmospheric and surface chemistry, physics, and mineralogy. The self-contained sensor network is based on our concept of an Addressable Photonics Cube (APC) which has real-time flexibility and broad science applications. It is envisaged that a spatially distributed autonomous sensor web concept that integrates multiple APCs will be reactive and dynamically driven. The network is designed to respond in an event- or model-driven manner or reconfigured as needed.

Hewagama, TIlak; Aslam, Shahid; Talabac, Stephen; Allen, John E., Jr.; Annen, John N.; Jennings, Donald E.

2011-01-01

418

Asymmetric multiple-image encryption based on coupled logistic maps in fractional Fourier transform domain  

NASA Astrophysics Data System (ADS)

A multiple-image encryption scheme is proposed based on the asymmetric technique, in which the encryption keys are not identical to the decryption ones. First, each plain image is scrambled based on a sequence of chaotic pairs generated with a system of two symmetrically coupled identical logistic maps. Then, the phase-only function of each scrambled image is retrieved with an iterative phase retrieval process in the fractional Fourier transform domain. Second, all phase-only functions are modulated into an interim, which is encrypted into the ciphertext with stationary white noise distribution by using the fractional Fourier transform and chaotic diffusion. In the encryption process, three random phase functions are used as encryption keys to retrieve the phase-only functions of plain images. Simultaneously, three decryption keys are generated in the encryption process, which make the proposed encryption scheme has high security against various attacks, such as chosen plaintext attack. The peak signal-to-noise is used to evaluate the quality of the decrypted image, which shows that the encryption capacity of the proposed scheme is enhanced considerably. Numerical simulations demonstrate the validity and efficiency of the proposed method.

Sui, Liansheng; Duan, Kuaikuai; Liang, Junli; Zhang, Zhiqiang; Meng, Haining

2014-11-01

419

Characterization of the dispersion of chirped fiber Bragg grating through Fourier transform spectrometry method  

NASA Astrophysics Data System (ADS)

Introduces a Fourier transform spectrometric method for the precise characterization of dispersion of chirped FBGs(fiber Bragg grating). The measurement system is a fiber Michelson interferometer composed of a broadband EDFA (Erium doped fiber amplifier) light source, a 3db 2×2 fiber coupler, a pair of polarization controllers, a optical attenuator, a fiber filter, an O/E converter, A/D converter, computer and a optical path difference (OPD) scanning system. The digital interferogram of the system is acquired by recording the electric signal produced by the O/E converter through the A/D converter and by computer during the scanning of OPD. The recorded interferogram is then manipulated through a process involving low-pass filtering, fast Fourier transformation, phase unwrapping and computation of the numerical differentials of the unwrapped phase to the wavelength so as to obtain the relative group delay of the chirped FBG under test. It is proved by practical experiments that the repeatability of the system is up to Ps(picosecond) magnitude order.

Chen, Qingshan; Lu, Naiguang; Jiang, Feng

2008-03-01

420

Quantitative diffuse reflectance infrared fourier transform spectrometric studies of cementitious blends  

SciTech Connect

The effective immobilization of low-level radioactive liquid wastes in the form of grout depends on the quality of the dry cementitious blends used in the grout formulation. Variation in the mix ratios of the components of the blend can cause detrimental effects on the processing behavior of the grout slurry and the final properties of the cured grout. Thus the blends require thorough chemical characterization and monitoring by strict quality control protocols. In an earlier work at our laboratories, Fourier transform infrared- transmission method has been successfully applied in the analysis of blends of cement, fly ash, and clays. However, this method involved time-consuming sample preparation resulting in slow turnaround for repetitive sampling. A practical approach to quality control required a fast and simple method for the analysis of the blends. This paper describes a diffuse reflectance infrared Fourier transform (DRIFT) spectrometric procedure for the routine examination of neat blends consisting of cement, fly ash, clays and/or blast furnace slags. (1 ref., 10 figs., 4 tabs.)

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

1989-07-01

421

Application of Fast Fourier Transform in thermo-magnetic convection analysis  

NASA Astrophysics Data System (ADS)

Application of Fast Fourier Transform in thermo-magnetic convection is reported. Cubical enclosure filled with paramagnetic fluid heated from below and placed in the strong magnetic field gradients was investigated. The main aim of study was connected with identification of flow types, especially transition to turbulence. For this purpose the Fast Fourier Transform (FFT) analysis was applied. It was followed by the heat transfer characteristic for various values of magnetic induction gradient. The analysis was done at two Rayleigh numbers 7.89·105 and 1.86·106 with thermo-magnetic Rayleigh numbers up to 1.8·108 and 4.5·108 respectively. The presented results clearly indicate flow types and also demonstrate augmented heat transfer in dependence on magnetic induction gradient. Detailed analysis of flow transition to turbulent state was compared with transition line for natural convection reported in literature. The transition to turbulence in the case of thermo-magnetic convection of paramagnetic fluid was in very good agreement with transition in the case of natural convection.

Pyrda, L.

2014-08-01

422

Identification of Earthquake Induced Damage Areas Using Fourier Transform and SPOT HRVIR Pan Images.  

PubMed

A devastating earthquake with a magnitude of Mw 7.4 occurred on the North Anatolian Fault Zone (NAFZ) of Turkey on August 17, 1999 at 00:01:39 UTC (3:01 a.m. local time). The aim of this study is to propose a new approach to automatically identify earthquake induced damage areas which can provide valuable information to support emergency response and recovery assessment procedures. This research was conducted in the Adapazari inner city, covering a 3 × 3 km area, where 11,373 buildings collapsed as a result of the earthquake. SPOT high resolution visible infrared (HRVIR) Pan images obtained before (25 June 1999) and after (4 October 1999) the earthquake were used in the study. Five steps were employed to conduct the research and these are: (i) geometric and radiometric correction of satellite images, (ii) Fast Fourier Transform (FFT) of pre- and post-earthquake images and filtering the images in frequency domain, (iii) generating difference image using Inverse Fast Fourier Transform (IFFT) pre- and post- earthquake images, (iv) application of level slicing to difference image to identify the earthquake-induced damages, (v) accuracy assessment of the method using ground truth obtained from a 1/5,000 scale damage map. The total accuracy obtained in the research is 80.19 %, illustrating that the proposed method can be successfully used to automatically identify earthquake-induced damage areas. PMID:22573966

Sertel, Elif

2009-01-01

423

Instrumental phase-based method for Fourier transform spectrometer measurements processing.  

PubMed

Phase correction is a critical procedure for most space-borne Fourier transform spectrometers (FTSs) whose accuracy (owing to often poor signal-to-noise ratio, SNR) can be jeopardized from many uncontrollable environmental conditions. This work considers the phase correction in an FTS working under significant temperature change during the measurement and affected by mechanical disturbances. The implemented method is based on the identification of an instrumental phase that is dependent on the interferometer temperature and on the extraction of a linear phase component through a least-squares approach. The use of an instrumental phase parameterized with the interferometer temperature eases the determination of the linear phase that can be extracted using only a narrow spectral region selected to be immune from disturbances. The procedure, in this way, is made robust against phase errors arising from instrumental effects, a key feature to reduce the disturbances through spectra averaging. The method was specifically developed for the Mars IR Mapper spectrometer, that was designed for operation onboard a rover on the Mars surface; the validation was performed using ground and in-flight measurements of the Fourier transform IR spectrometer planetary Fourier spectrometer, onboard the MarsExpress mission. The symmetrization has been exploited also for the spectra calibration, highlighting the issues deriving from the cases of relevant beamsplitter emission. The applicability of this procedure to other instruments is conditional to the presence in the spectra of at least one spectral region with a large SNR along with a negligible (or known) beamsplitter emission. For the PFS instrument, the processing of data with relevant beamsplitter emission has been performed exploiting the absorption carbon dioxide bands present in Martian spectra. PMID:21509063

Saggin, Bortolino; Scaccabarozzi, Diego; Tarabini, Marco

2011-04-20

424

Photon echo quantum memory and state transformation  

NASA Astrophysics Data System (ADS)

A recently proposed, photon echo related approach to quantum state storage in atomic ensembles employs controlled reversible inhomogeneous broadening (CRIB). Beyond storage, a modified version of CRIB promises controlled quantum state manipulations. As the implementation of CRIB is currently still challenging, we investigate state transformation based on stimulated photon echoes. Specifically, we show how to translate an all optical, beamsplitter based setup into a photon echo based setup, and we simulate a photon echo based POVM (positive operator valued measure) measurement using Maxwell-Bloch equations.

Delfan, A.; La Mela, C.; Tittel, W.

2008-02-01

425

Two dimensional symmetric correlation functions of the ? operator and two dimensional Fourier transforms: considering the line coupling for P and R lines of linear molecules.  

PubMed

The refinement of the Robert-Bonamy (RB) formalism by considering the line coupling for isotropic Raman Q lines of linear molecules developed in our previous study [Q. Ma, C. Boulet, and R. H. Tipping, J. Chem. Phys. 139, 034305 (2013)] has been extended to infrared P and R lines. In these calculations, the main task is to derive diagonal and off-diagonal matrix elements of the Liouville operator iS1 - S2 introduced in the formalism. When one considers the line coupling for isotropic Raman Q lines where their initial and final rotational quantum numbers are identical, the derivations of off-diagonal elements do not require extra correlation functions of the ? operator and their Fourier transforms except for those used in deriving diagonal elements. In contrast, the derivations for infrared P and R lines become more difficult because they require a lot of new correlation functions and their Fourier transforms. By introducing two dimensional correlation functions labeled by two tensor ranks and making variable changes to become even functions, the derivations only require the latters' two dimensional Fourier transforms evaluated at two modulation frequencies characterizing the averaged energy gap and the frequency detuning between the two coupled transitions. With the coordinate representation, it is easy to accurately derive these two dimensional correlation functions. Meanwhile, by using the sampling theory one is able to effectively evaluate their two dimensional Fourier transforms. Thus, the obstacles in considering the line coupling for P and R lines have been overcome. Numerical calculations have been carried out for the half-widths of both the isotropic Raman Q lines and the infrared P and R lines of C2H2 broadened by N2. In comparison with values derived from the RB formalism, new calculated values are significantly reduced and become closer to measurements. PMID:24628166

Ma, Q; Boulet, C; Tipping, R H

2014-03-14

426

Two dimensional symmetric correlation functions of the S-circumflex operator and two dimensional Fourier transforms: Considering the line coupling for P and R lines of linear molecules  

SciTech Connect

The refinement of the Robert-Bonamy (RB) formalism by considering the line coupling for isotropic Raman Q lines of linear molecules developed in our previous study [Q. Ma, C. Boulet, and R. H. Tipping, J. Chem. Phys. 139, 034305 (2013)] has been extended to infrared P and R lines. In these calculations, the main task is to derive diagonal and off-diagonal matrix elements of the Liouville operator iS{sub 1} ? S{sub 2} introduced in the formalism. When one considers the line coupling for isotropic Raman Q lines where their initial and final rotational quantum numbers are identical, the derivations of off-diagonal elements do not require extra correlation functions of the S-circumflex operator and their Fourier transforms except for those used in deriving diagonal elements. In contrast, the derivations for infrared P and R lines become more difficult because they require a lot of new correlation functions and their Fourier transforms. By introducing two dimensional correlation functions labeled by two tensor ranks and making variable changes to become even functions, the derivations only require the latters’ two dimensional Fourier transforms evaluated at two modulation frequencies characterizing the averaged energy gap and the frequency detuning between the two coupled transitions. With the coordinate representation, it is easy to accurately derive these two dimensional correlation functions. Meanwhile, by using the sampling theory one is able to effectively evaluate their two dimensional Fourier transforms. Thus, the obstacles in considering the line coupling for P and R lines have been overcome. Numerical calculations have been carried out for the half-widths of both the isotropic Raman Q lines and the infrared P and R lines of C{sub 2}H{sub 2} broadened by N{sub 2}. In comparison with values derived from the RB formalism, new calculated values are significantly reduced and become closer to measurements.

Ma, Q. [NASA/Goddard Institute for Space Studies and Department of Applied Physics and Applied Mathematics, Columbia University, 2880 Broadway, New York, New York 10025 (United States)] [NASA/Goddard Institute for Space Studies and Department of Applied Physics and Applied Mathematics, Columbia University, 2880 Broadway, New York, New York 10025 (United States); Boulet, C. [Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS (UMR8214) et Université Paris-Sud Bât 350, Campus d'Orsay F-91405 (France)] [Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS (UMR8214) et Université Paris-Sud Bât 350, Campus d'Orsay F-91405 (France); Tipping, R. H. [Department of Physics and Astronomy, University of Alabama, Tuscaloosa, Alabama 35487-0324 (United States)] [Department of Physics and Astronomy, University of Alabama, Tuscaloosa, Alabama 35487-0324 (United States)

2014-03-14

427

Real-time 2D floating-point fast Fourier transforms for seeker simulation  

NASA Astrophysics Data System (ADS)

The floating point Fast Fourier Transform (FFT) is one of the most useful basic functions available to the image and signal processing engineer allowing many complex and detailed special functions to be implemented more simply in the frequency domain. In the Hardware-in-the-Loop field an image transformed using FFT would allow the designer to think about accurate frequency based simulation of seeker lens effects, motion blur, detector transfer functions and much more. Unfortunately, the transform requires many hundreds of thousands or millions of floating point operations on a single modest sized image making it impractical for realtime Hardware-in-the-Loop systems. .until now. This paper outlines the development, by Nallatech, of an FPGA based IEEE floating point core. It traces the subsequent use of this core to develop a full 256 X 256 FFT and filter process implemented on COTS hardware at frame rates up to 150Hz. This transform can be demonstrated to model optical transfer functions at a far greater accuracy than the current spatial models. Other applications and extensions of this technique will be discussed such as filtering for image tracking algorithms and in the simulation of radar processing in the frequency domain.

Chamberlain, Richard; Lord, Eric; Shand, David J.

2002-07-01

428

Equal Superposition Transformations and Quantum Random Walks  

E-print Network

The largest ensemble of qubits which satisfy the general transformation of equal superposition is obtained by different methods, namely, linearity, no-superluminal signalling and non-increase of entanglement under LOCC. We also consider the associated quantum random walk and show that all unitary balanced coins give the same asymmetric spatial probability distribution. It is further illustrated that unbalanced coins, upon appropriate superposition, lead to new unbiased walks which have no classical analogues.

Preeti Parashar

2007-09-21

429

Continuous wavelet transform in quantum field theory  

NASA Astrophysics Data System (ADS)

We describe the application of the continuous wavelet transform to calculation of the Green functions in quantum field theory: scalar ?4 theory, quantum electrodynamics, and quantum chromodynamics. The method of continuous wavelet transform in quantum field theory, presented by Altaisky [Phys. Rev. D 81, 125003 (2010)] for the scalar ?4 theory, consists in substitution of the local fields ?(x) by those dependent on both the position x and the resolution a. The substitution of the action S[?(x)] by the action S[?a(x)] makes the local theory into a nonlocal one and implies the causality conditions related to the scale a, the region causality [J. D. Christensen and L. Crane, J. Math. Phys. (N.Y.) 46, 122502 (2005)]. These conditions make the Green functions G(x1,a1,…,xn,an)=??a1(x1)…?an(xn)? finite for any given set of regions by means of an effective cutoff scale A=min?(a1,…,an).

Altaisky, M. V.; Kaputkina, N. E.

2013-07-01

430

Multi-resolution Graph Fourier Transform for Compression of Piecewise Smooth Images.  

PubMed

Piecewise smooth (PWS) images (e.g., depth maps or animation images) contain unique signal characteristics such as sharp object boundaries and slowly-varying interior surfaces. Leveraging on recent advances in graph signal processing, in this paper we propose to compress PWS images using suitable Graph Fourier Transforms (GFT) to minimize the total signal representation cost of each pixel block, considering both the sparsity of the signal's transform coefficients and the compactness of transform description. Unlike fixed transforms such as the Discrete Cosine Transform (DCT), we can adapt GFT to a particular class of pixel blocks. In particular, we select one among a defined search space of GFTs to minimize total representation cost via our proposed algorithms, leveraging on graph optimization techniques such as spectral clustering and minimum graph cuts. Further, for practical implementation of GFT we introduce two techniques to reduce computation complexity. First, at the encoder we low-pass filter and down-sample a high-resolution (HR) pixel block to obtain a low-resolution (LR) one, so that a LR-GFT can be employed. At the decoder, up-sampling and interpolation are performed adaptively along HR boundaries coded using arithmetic edge coding (AEC), so that sharp object boundaries can be well preserved. Second, instead of computing GFT from a graph in real-time via eigen-decomposition, the most popular LR-GFTs are pre-computed and stored in a table for lookup during encoding and decoding. Using depth maps and computer-graphics images as examples of PWS images, experimental results show that our proposed multi-resolution (MR)-GFT scheme outperforms H.264 intra by 6:8 dB on average in PSNR at the same bit rate. PMID:25494508

Hu, Wei; Cheung, Gene; Ortega, Antonio; Au, Oscar

2014-12-01

431

Structural studies of cucumber mosaic virus: Fourier transform infrared spectroscopic studies.  

PubMed

The secondary structure of cucumber mosaic virus (CMV) was investigated in solution using Fourier transform infrared (FT-IR) spectroscopy. The amide I region of intact CMV revealed a doublet at 1671 cm-1 and 1653 cm-1, respectively. In order to isolate the IR bands arising from the protein backbone of CMV, the FT-IR spectra of the RNA component, isolated by phenol-SDS treatment of purified CMV and subsequent precipitation by ethanol, was obtained separately and digitally subtracted from the intact CMV spectra. After digital subtraction, the amide I region contained two bands at 1682 cm-1 and 1644 cm-1. The former band was ascribed to beta-sheet structures, while the later band occurs in the region between alpha-helix and "unordered" structures. Resolution enhancement of the finger print amide I region was accomplished using Fourier self-deconvolution of the digitally subtracted FT-IR spectrum of CMV which further confirmed the presence of anti-parallel beta-sheet structure in the protein coat of CMV. Chou-Fasman predictions on the the coat protein also revealed the presence of beta-sheet structure in agreement with FT-IR studies. PMID:9844736

Renugopalakrishnan, V; Piazzolla, P; Tamburro, A M; Lamba, O P

1998-11-01

432

Fast dose kernel interpolation using Fourier transform with application to permanent prostate brachytherapy dosimetry  

SciTech Connect

Purpose: Boyer and Mok proposed a fast calculation method employing the Fourier transform (FT), for which calculation time is independent of the number of seeds but seed placement is restricted to calculation grid points. Here an interpolation method is described enabling unrestricted seed placement while preserving the computational efficiency of the original method. Methods: The Iodine-125 seed dose kernel was sampled and selected values were modified to optimize interpolation accuracy for clinically relevant doses. For each seed, the kernel was shifted to the nearest grid point via convolution with a unit impulse, implemented in the Fourier domain. The remaining fractional shift was performed using a piecewise third-order Lagrange filter. Results: Implementation of the interpolation method greatly improved FT-based dose calculation accuracy. The dose distribution was accurate to within 2% beyond 3 mm from each seed. Isodose contours were indistinguishable from explicit TG-43 calculation. Dose-volume metric errors were negligible. Computation time for the FT interpolation method was essentially the same as Boyer's method. Conclusions: A FT interpolation method for permanent prostate brachytherapy TG-43 dose calculation was developed which expands upon Boyer's original method and enables unrestricted seed placement. The proposed method substantially improves the clinically relevant dose accuracy with negligible additional computation cost, preserving the efficiency of the original method.

Liu, Derek, E-mail: dmliu@ualberta.ca; Sloboda, Ron S. [Department of Medical Physics, Cross Cancer Institute, Edmonton, Alberta T6G 1Z2, Canada and Department of Oncology, University of Alberta, Edmonton, Alberta T6G 2R3 (Canada)] [Department of Medical Physics, Cross Cancer Institute, Edmonton, Alberta T6G 1Z2, Canada and Department of Oncology, University of Alberta, Edmonton, Alberta T6G 2R3 (Canada)

2014-05-15

433

Measuring the temporal coherence of a high harmonic generation setup employing a Fourier transform spectrometer for the VUV/XUV  

NASA Astrophysics Data System (ADS)

In this experiment we used an 800 nm laser to generate high-order harmonics in a gas cell filled with Argon. Of those photons, a harmonic with 42 eV was selected by using a time-preserving grating monochromator. Employing a modified Mach-Zehnder type Fourier transform spectrometer for the VUV/XUV it was possible to measure the temporal coherence of the selected photons to about 6 fs. We demonstrated that not only could this kind of measurement be performed with a Fourier transform spectrometer, but also with some spatial resolution without modifying the XUV source or the spectrometer.

Terschlüsen, J. A.; Agåker, M.; Svanqvist, M.; Plogmaker, S.; Nordgren, J.; Rubensson, J.-E.; Siegbahn, H.; Söderström, J.

2014-12-01

434

Predicting the thermal/structural performance of the atmospheric trace molecules spectroscopy /ATMOS/ Fourier transform spectrometer  

NASA Technical Reports Server (NTRS)

ATMOS is a Fourier transform spectrometer to measure atmospheric trace molecules over a spectral range of 2-16 microns. Assessment of the system performance of ATMOS includes evaluations of optical system errors induced by thermal and structural effects. In order to assess the optical system errors induced from thermal and structural effects, error budgets are assembled during system engineering tasks and line of sight and wavefront deformations predictions (using operational thermal and vibration environments and computer models) are subsequently compared to the error budgets. This paper discusses the thermal/structural error budgets, modelling and analysis methods used to predict thermal/structural induced errors and the comparisons that show that predictions are within the error budgets.

Miller, J. M.

1980-01-01

435

Spaceborne infrared Fourier-transform spectrometers for temperature and humidity sounding of the Earth's atmosphere  

NASA Astrophysics Data System (ADS)

A spaceborne Fourier-transform infrared (FTIR) spectrometer was designed for measuring the spectra of the outgoing Earth's atmosphere radiation and serves for providing for the needs of online meteorology and climatology with regard to obtaining the following kinds of data: vertical profiles of temperature and humidity profiles in the troposphere and the lower stratosphere, the general and altitudinal ozone distribution, concentrations of small gaseous constituents, temperature of the underlying surface, etc. At present, works are underway at the Keldysh Research Centre for creating IKFS-series FTIR spectrometers for satellites in Sun-synchronous orbits: the IKFS-2 instrument for the Meteor-M spacecraft no. 2 of the Meteor-3M space complex (developed and supplied for testing together with the spacecraft) and an advanced IKFS-3 instrument for the Meteor-MP fourth-generation hydrometeorological and oceanographic space complex for Earth monitoring (at the developmental stage). The composition, functional diagram, and technical specifications of the FTIR spectrometers are presented.

Golovin, Yu. M.; Zavelevich, F. S.; Nikulin, A. G.; Kozlov, D. A.; Monakhov, D. O.; Kozlov, I. A.; Arkhipov, S. A.; Tselikov, V. A.; Romanovskii, A. S.

2014-12-01

436

Nuclear Spin-Echo Fourier-Transform Mapping Spectroscopy for Broad NMR Lines in Solids  

NASA Astrophysics Data System (ADS)

A basic theoretical description of nuclear spin-echo Fourier-transform mapping spectroscopy (NSEFTMS) for broad NMR lines was derived from the well-established time-domain spin-echo theory. It has been shown that when the mapping step is less than the radiation field strength under typical conditions of spin-echo experiments, the NSEFTMS mimics precisely the original NMR spectrum. Most important, the NSEFTMS present a more efficient alternative in practice to the conventional point-by-point scanning technique that is, in general, time consuming in studying broad NMR lines in solids, especially when there exist some sharp features. A preliminary 31P NMR study of an iron (II) diphosphate (Fe 2P 2O 7) sample, which is one kind of precursor for the heterogeneous catalytic ferri-phosphate system (FePO), has been taken as an example of the application of the theory.

Tong, Y. Y.

437

New scientific results with SpIOMM: a testbed for CFHT's imaging Fourier transform spectrometer SITELLE  

NASA Astrophysics Data System (ADS)

We present new data obtained with SpIOMM, the imaging Fourier transform spectrometer attached to the 1.6-m telescope of the Observatoire du Mont-Megantic in Québec. Recent technical and data reduction improvements have significantly increased SpIOMM's capabilities to observe fainter objects or weaker nebular lines, as well as continuum sources and absorption lines, and to increase its modulation efficiency in the near ultraviolet. To illustrate these improvements, we present data on the supernova remnant Cas A, planetary nebulae M27 and M97, the Wolf-Rayet ring nebula M1-67, spiral galaxies M63 and NGC 3344, as well as the interacting pair of galaxies Arp 84.

Drissen, L.; Alarie, A.; Martin, T.; Lagrois, D.; Rousseau-Nepton, L.; Bilodeau, A.; Robert, C.; Joncas, G.; Iglesias-Páramo, J.

2012-09-01

438

Techniques for computing the discrete Fourier transform using the quadratic residue Fermat number systems  

NASA Technical Reports Server (NTRS)

The complex integer multiplier and adder over the direct sum of two copies of finite field developed by Cozzens and Finkelstein (1985) is specialized to the direct sum of the rings of integers modulo Fermat numbers. Such multiplication over the rings of integers modulo Fermat numbers can be performed by means of two integer multiplications, whereas the complex integer multiplication requires three integer multiplications. Such multiplications and additions can be used in the implementation of a discrete Fourier transform (DFT) of a sequence of complex numbers. The advantage of the present approach is that the number of multiplications needed to compute a systolic array of the DFT can be reduced substantially. The architectural designs using this approach are regular, simple, expandable and, therefore, naturally suitable for VLSI implementation.

Truong, T. K.; Chang, J. J.; Hsu, I. S.; Pei, D. Y.; Reed, I. S.

1986-01-01

439

Fourier transform infrared spectroscopy quantitative analysis of SF6 partial discharge decomposition components  

NASA Astrophysics Data System (ADS)

Gas-insulated switchgear (GIS) internal SF6 gas produces specific decomposition components under partial discharge (PD). By detecting these characteristic decomposition components, such information as the type and level of GIS internal insulation deterioration can be obtained effectively, and the status of GIS internal insulation can be evaluated. SF6 was selected as the background gas for Fourier transform infrared spectroscopy (FTIR) detection in this study. SOF2, SO2F2, SO2, and CO were selected as the characteristic decomposition components for system analysis. The standard infrared absorption spectroscopy of the four characteristic components was measured, the optimal absorption peaks were recorded and the corresponding absorption coefficient was calculated. Quantitative detection experiments on the four characteristic components were conducted. The volume fraction variation trend of four characteristic components at different PD time were analyzed. And under five different PD quantity, the quantitative relationships among gas production rate, PD time, and PD quantity were studied.

Zhang, Xiaoxing; Liu, Heng; Ren, Jiangbo; Li, Jian; Li, Xin

2015-02-01

440

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

SciTech Connect

Fourier Transform Infrared Photoacoustic Spectroscopy (FTIR-PAS) has been applied for the first time to the identification and speciation of bacterial spores. With minimal preparation the spores were deposited into the photoacoustic sample cup and their spectra recorded. A total of 40 different samples of 5 different strains of Bacillus spores were analyzed: Bacillus subtilis ATCC 49760, Bacillus atrophaeus ATCC 49337, Bacillus subtilis 6051, Bacillus thuringiensis ssp. kurstaki, and Bacillus globigii Dugway. The statistical methods used included principal-component analysis (PCA), classification and regression trees (CART), and Mahalanobis-distance calculations. Internal cross-validation studies successfully classify the spores according to their bacterial strain in 38 of 40 cases (95%) and 36 of 40 (90%) in cross-validation. Analysis of fifteen blind samples, which included library and other spores, and nonbacterial materials, resulted in correct strain classification the blind samples that were members of the library and correct rejection of the nonbacterial samples.

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

2003-08-28

441

Fourier transform mid infrared spectroscopy applications for monitoring the structural plasticity of plant cell walls  

PubMed Central

Fourier transform mid-infrared (FT-MIR) spectroscopy has been extensively used as a potent, fast and non-destructive procedure for analyzing cell wall architectures, with the capacity to provide abundant information about their polymers, functional groups, and in muro entanglement. In conjunction with multivariate analyses, this method has proved to be a valuable tool for tracking alterations in cell walls. The present review examines recent progress in the use of FT-MIR spectroscopy to monitor cell wall changes occurring in muro as a result of various factors, such as growth and development processes, genetic modifications, exposition or habituation to cellulose biosynthesis inhibitors and responses to other abiotic or biotic stresses, as well as its biotechnological applications. PMID:25071791

Largo-Gosens, Asier; Hernández-Altamirano, Mabel; García-Calvo, Laura; Alonso-Simón, Ana; Álvarez, Jesús; Acebes, José L.

2014-01-01

442

Identification of Trueperella pyogenes Isolated from Bovine Mastitis by Fourier Transform Infrared Spectroscopy  

PubMed Central

The present study was designed to investigate the potential of Fourier transform infrared (FT-IR) spectroscopy to identify Trueperella (T.) pyogenes isolated from bovine clinical mastitis. FT-IR spectroscopy was applied to 57 isolates obtained from 55 cows in a period from 2009 to 2012. Prior to FT-IR spectroscopy these isolates were identified by phenotypic and genotypic properties, also including the determination of seven potential virulence factor encoding genes. The FT-IR analysis revealed a reliable identification of all 57 isolates as T. pyogenes and a clear separation of this species from the other species of genus Trueperella and from species of genus Arcanobacterium and Actinomyces. The results showed that all 57 isolates were assigned to the correct species indicating that FT-IR spectroscopy could also be efficiently used for identification of this bacterial pathogen. PMID:25133407

Nagib, Samy; Rau, Jörg; Sammra, Osama; Lämmler, Christoph; Schlez, Karen; Zschöck, Michael; Prenger-Berninghoff, Ellen; Klein, Guenter; Abdulmawjood, Amir

2014-01-01

443

Fourier Transform Spectroscopy of the Y2? +-X2? iTransition of CuO  

NASA Astrophysics Data System (ADS)

The Y2? +-X2? inear-infrared electronic transition of CuO was observed at high resolution for the first time. The spectrum was recorded with the Fourier transform spectrometer associated with the McMath-Pierce Solar Telescope at Kitt Peak. The excited CuO molecules were produced in a low pressure copper hollow cathode sputter with a slow flow of oxygen. Constants for the Y2? +states of CuO are: T0= 7715.47765(54) cm -1, B= 0.4735780(28) cm -1, D= 0.822(12) × 10 -6cm -1, H= 0.46(10) × 10 -10cm -1, ? = -0.089587(42) cm -1, ? D= 0.1272(79) × 10 -6cm -1, bF= 0.12347(22) cm -1, and c= 0.0550(74) cm -1. Improved X2? iconstants are also presented.

O'brien, L. C.; Kubicek, R. L.; Wall, S. J.; Koch, D. E.; Friend, R. J.; Brazier, C. R.

1996-12-01

444

Polyphase-discrete Fourier transform spectrum analysis for the Search for Extraterrestrial Intelligence sky survey  

NASA Technical Reports Server (NTRS)

The sensitivity of a matched filter-detection system to a finite-duration continuous wave (CW) tone is compared with the sensitivities of a windowed discrete Fourier transform (DFT) system and an ideal bandpass filter-bank system. These comparisons are made in the context of the NASA Search for Extraterrestrial Intelligence (SETI) microwave observing project (MOP) sky survey. A review of the theory of polyphase-DFT filter banks and its relationship to the well-known windowed-DFT process is presented. The polyphase-DFT system approximates the ideal bandpass filter bank by using as few as eight filter taps per polyphase branch. An improvement in sensitivity of approx. 3 dB over a windowed-DFT system can be obtained by using the polyphase-DFT approach. Sidelobe rejection of the polyphase-DFT system is vastly superior to the windowed-DFT system, thereby improving its performance in the presence of radio frequency interference (RFI).

Zimmerman, G. A.; Gulkis, S.

1991-01-01

445

Series expansion for the Fourier transform of a rational function in three dimensions  

E-print Network

In Rashba-Dresselhaus spin-orbit coupled systems, the calculation of Green's function requires the knowledge of the inverse Fourier transform of rational function $P(p)/Q(p)$, where $P(p)$ takes the values $1$ and $p^{2}$, and where \\[ Q(p)=(p^{2}-\\zeta)^{2}- \\alpha^{2}(p_{1}^{2}+p_{2}^{2})-\\beta^{2} \\] with suitable parameters $\\alpha$, $\\beta\\geq0$, $\\zeta\\in\\mathbb{C}$. While a two-dimensional problem, with $p=(p_{1},p_{2})$, has been recently solved [J. Br\\"{u}ning et al, J. Phys. A: Math. Theor. 40 (2007)], its three-dimensional analogue, with $p=(p_{1},p_{2},p_{3})$, remains open. In this paper, a hypergeometric series expansion for the triple integral is provided. Convergence of the series dependent on the parameters is studied in detail.

Rytis Jursenas

2014-10-20

446

Attenuated total reflectance Fourier transform infrared spectroscopy analysis of red seal inks on questioned document.  

PubMed

Seals are traditionally used in the Far East Asia to stamp an impression on a document in place of a signature. In this study, an accuser claimed that a personal contract regarding mining development rights acquired by a defendant was devolved to the accuser because the defendant stamped the devolvement contract in the presence of the accuser and a witness. The accuser further stated that the seal ink stamped on the devolvement contract was the same as that stamped on the development rights application document. To verify this, the seals used in two documents were analyzed using micro-attenuated total reflectance Fourier transform infrared spectroscopy and infrared spectra. The findings revealed that the seals originated from different manufacturers. Thus, the accuser's claim on the existence of a devolvement contract was proved to be false. PMID:24844350

Nam, Yun Sik; Park, Jin Sook; Kim, Nak-Kyoon; Lee, Yeonhee; Lee, Kang-Bong

2014-07-01

447

Fourier transform infrared spectroscopy quantitative analysis of SF6 partial discharge decomposition components.  

PubMed

Gas-insulated switchgear (GIS) internal SF6 gas produces specific decomposition components under partial discharge (PD). By detecting these characteristic decomposition components, such information as the type and level of GIS internal insulation deterioration can be obtained effectively, and the status of GIS internal insulation can be evaluated. SF6 was selected as the background gas for Fourier transform infrared spectroscopy (FTIR) detection in this study. SOF2, SO2F2, SO2, and CO were selected as the characteristic decomposition components for system analysis. The standard infrared absorption spectroscopy of the four characteristic components was measured, the optimal absorption peaks were recorded and the corresponding absorption coefficient was calculated. Quantitative detection experiments on the four characteristic components were conducted. The volume fraction variation trend of four characteristic components at different PD time were analyzed. And under five different PD quantity, the quantitative relationships among gas production rate, PD time, and PD quantity were studied. PMID:25459612

Zhang, Xiaoxing; Liu, Heng; Ren, Jiangbo; Li, Jian; Li, Xin

2015-02-01

448

Fourier transform atomic emission studies using a glow discharge as the emission source  

NASA Astrophysics Data System (ADS)

The glow discharge (GD) is investigated as a possible atomic emission source for Fourier transform atomic emission spectroscopy (FT-AES). Noise power spectra are presented to demonstrate that GD emission is primarily characterized by photon noise, although a drift noise component exists at extremely low frequencies. The photon noise character is important, since photon noise limited sources are expected to outperform source flicker noise limited sources in terms of measurement precision. The implementation of bandpass restriction and dual channel subtractive noise cancellation as possible means of improving measurement precision are also presented. In both cases, the improvements were found to be minimal, a fact attributed to the probable suitability of the GD for FT-AES.

Winchester, Michael R.; Travis, John C.; Salit, Marc L.

1993-09-01

449

Feasibility investigation of integrated optics Fourier transform devices. [holographic subtraction for multichannel data preprocessing  

NASA Technical Reports Server (NTRS)

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 systems were investigated. Activities toward this goal include; (1) production of near-diffraction-limited geodesic lenses in glass waveguides; (2) development of grinding and polishing techniques for the production of geodesic lenses in LiNbO3 waveguides; (3) development of a characterization technique for waveguide lenses; and (4) development of a theory for corrected aspheric geodesic lenses. A holographic subtraction system was devised which should be capable of rapid on-board preprocessing of a large number of parallel data channels. The principle involved is validated in three demonstrations.

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

1977-01-01

450

Use of in situ Fourier transform infrared spectroscopy to study freezing and drying of cells.  

PubMed

An infrared spectrum gives information about characteristic molecular vibrations of specific groups in molecules. Fourier transform infrared spectroscopy can be applied to study lipids and proteins in cells or tissues. Spectra can be collected during cooling, heating, or dehydration of a sample using a temperature-controlled sample holder or a sample holder for controlled dehydration. In the current chapter, acquisition and analysis of infrared spectra during cooling, warming, or dehydration is described. Spectra analysis involving assessment of specific band positions, areas, or ratios is described. Special emphasis is given on studying membrane phase behavior and protein denaturation in cells or tissues. In addition, methods are presented to determine the water-to-ice phase change during freezing, dehydration kinetics, and the glass transition temperature of amorphous systems. PMID:25428005

Wolkers, Willem F; Oldenhof, Harriëtte

2015-01-01

451

Fourier transform microwave spectroscopy of the reactive intermediate monoiodosilylene, HSiI and DSiI  

NASA Astrophysics Data System (ADS)

The pure rotational spectra of three silicon isotopologues of HSiI and two isotopologues of DSiI have been recorded by pulsed-jet Fourier transform microwave (FTMW) spectroscopy. Neon was passed over dry ice cooled H 3SiI or D 3SiI and introduced into the pulsed valve of the FTMW spectrometer. The monoiodosilylenes HSiI and DSiI were produced in situ with a 1000 V DC-discharge nozzle. Only a-type transitions occur in monoiodosilylene from 6 to 26 GHz. We observe K a = 0 a-type transitions for H 28SiI, H 29SiI, H 30SiI, and D 29SiI, and both K a = 0 and 1 a-type transitions for D 28SiI. Rotational constants, centrifugal distortion constants, iodine nuclear quadrupole coupling constants, and nuclear spin-molecular rotation constants were measured.

Kang, Lu; Gharaibeh, Mohammed A.; Clouthier, Dennis J.; Novick, Stewart E.

2012-01-01

452

Spherical T-Duality and the spherical Fourier-Mukai transform  

E-print Network

In [arxiv:1405.5844], we introduced spherical T-duality, which relates pairs of the form $(P,H)$ consisting of a principal $SU(2)$-bundle $P\\rightarrow M$ and a 7-cocycle $H$ on $P$. Intuitively, spherical T-duality exchanges $H$ with the second Chern class $c_2(P)$. Unless $\\mathrm{dim}(M)\\leq 4$, not all pairs admit spherical T-duals and the spherical T-duals are not always unique. In this paper, we define a canonical spherical Poincar\\'e vector bundle $\\mathcal P$ on $SU(2)\\times SU(2)$ and the spherical Fourier-Mukai transform, which implements a degree shifting isomorphism in K-theory on the trivial $SU(2)$-bundle with trivial 7-flux, and then (partially) generalise it to prove that all spherical T-dualities induce a natural degree-shifting isomorphism on the 7-twisted K-theories of the bundles when $\\mathrm{dim}(M)\\leq 4$.

Bouwknegt, Peter; Mathai, Varghese

2015-01-01

453

Propagation of Bessel-Gaussian beams through a double-apertured fractional Fourier transform optical system.  

PubMed

Based on the scalar diffraction theory and the fact that a hard-edged aperture function can be expanded into a finite sum of complex Gaussian functions, an approximate analytical solution for Bessel-Gaussian (BG) beams propagating through a double-apertured fractional Fourier transform (FrFT) system is derived in the cylindrical coordinate. By using the approximate analytical formulas, the propagation properties of BG beams passing through a double-apertured FrFT optical system have been studied in detail by some typical numerical examples. The results indicate that the double-apertured FrFT optical system provides a convenient way for controlling the properties of the BG beams by properly choosing the optical parameters. PMID:23201891

Tang, Bin; Jiang, Chun; Zhu, Haibin

2012-08-01

454

Fourier Transform Microwave Spectroscopy of Alkali Metal Hydrosulfides: Detection of Ksh  

NASA Astrophysics Data System (ADS)

Fourier transform microwave (FTMW) techniques have been used to record pure rotational spectra of potassium hydrosulfide and its deuterium isotopologue in their ground electronic states. This study represents the first gas phase spectroscopic observation of KSH. FTMW spectra of NaSH were also recorded. The metal hydrosulfides were produced by discharge assisted laser ablation of the solid alkali metal in the presence of hydrogen sulfide or deuterated hydrogen sulfide. Rotational transitions in the 5-20 GHz range were measured and hyperfine splittings due to the alkali metals and deuterium were resolved. Rotational as well as metal and deuterium quadrupole coupling constants have been determined from the data. The hyperfine parameters will be interpreted in terms of metal-ligand bonding character. Geometric parameters of the alkali metal hydrosulfides will be compared.

Sheridan, P. M.; Binns, M. K. L.; Young, J. P.; Bucchino, M. P.; Ziurys, L. M.

2012-06-01

455

Estimation of multiple accelerated motions using chirp-Fourier transform and clustering.  

PubMed

Motion estimation in the spatiotemporal domain has been extensively studied and many methodologies have been proposed, which, however, cannot handle both time-varying and multiple motions. Extending previously published ideas, we present an efficient method for estimating multiple, linearly time-varying motions. It is shown that the estimation of accelerated motions is equivalent to the parameter estimation of superpositioned chirp signals. From this viewpoint, one can exploit established signal processing tools such as the chirp-Fourier transform. It is shown that accelerated motion results in energy concentration along planes in the 4-D space: spatial frequencies-temporal frequency-chirp rate. Using fuzzy c-planes clustering, we estimate the plane/motion parameters. The effectiveness of our method is verified on both synthetic as well as real sequences and its advantages are highlighted. PMID:17283773

Alexiadis, Dimitrios S; Sergiadis, George D

2007-01-01

456

Electrospray ionization Fourier transform mass spectrometric analysis of intact bikunin glycosaminoglycan from normal human plasma  

PubMed Central

A mixture of glycosaminoglycan (GAG) chains from a plasma proteoglycan bikunin was fractionated using native, continuous-elution polyacrylamide gel electrophoresis, and the resulting fractions were analyzed by electrospray ionization Fourier transform mass spectrometry (ESI FTMS). Molecular mass analysis of the intact GAG afforded information about the length and composition of GAG chains in the mixture. Ambiguity in the interpretation of the intact GAG mass spectra was eliminated by conducting an additional experiment in which the GAG chains of known molecular mass were treated with a GAG-degrading enzyme, chondroitinase ABC, and the digestion products were analyzed by ESI FTMS. The plasma bikunin GAG chains consisted predominantly of odd number of saccharides, although few chains consisting of even number of saccharides were also detected. Majority of the analyzed chains were tetrasulfated or pentasulfated and comprised by 29 to 41 monosaccharides. PMID:21860600

Laremore, Tatiana N.; Leach, Franklin E.; Amster, I. Jonathan; Linhardt, Robert J.

2010-01-01

457

Examination of the thermal decomposition of kraft pine lignin by Fourier transform infrared evolved gas analysis  

SciTech Connect

The thermal decomposition of kraft lignin was examined by Fourier-transform IR evolved-gas analysis, a technique designed for on-the-fly, simultaneous monitoring of multiple vapor-phase species. Initial degradation occurs at 120-300 degrees from bond fragmentation in the phenylpropane side chains as evidenced by the formation of HCO2H, HCHO, CO2, H2O and SO2. The presence of SO2 is supporting evidence that S from the kraft pulping process may be incorporated into the lignin structure in the form of sulfoxide and(or) sulfone linkages. Major decomposition initiates at approximately 300 degrees and extends to 480 degrees at which point half the intital weight has been lost. MeOH 2-methoxyphenol (guaiacol), and a 2-methoxy-4-alkyl- substituted phenol are the most apparent species evolving in this region and indicate fragmentation of the major chain linkages between the monomeric phenol units in the lignin structure.

Fenner, R.A.; Lephardt, J.O.

1981-01-01

458

Investigation of the metabolism of ergot alkaloids in cell culture by fourier transformation mass spectrometry.  

PubMed

Ergot alkaloids are known toxic secondary metabolites of the fungus Claviceps purpurea occurring in various grains, especially rye products. The liver is responsible for converting the ergot alkaloids into metabolites; however, the toxic impact of these end products of metabolism is still unknown. The aim of this study was to analyze the metabolism of ergot alkaloids in colon and liver cell lines (HT-29, HepG2), as well as in human primary renal cells (RPTEC). It was shown that cells in vitro are able to metabolize ergot alkaloids, forming a variety of metabolic compounds. Significant differences between the used cell types could be identified, and a suitable model system was established using HT-29 cells, performing an intensive metabolism to hydroxylated metabolites. The formed substances were analyzed by coupling of high-performance liquid chromatography with fluorescence detection and Fourier transformation mass spectrometry (HPLC-FLD-FTMS) as a powerful tool to identify known and unknown metabolites. PMID:21650459

Mulac, Dennis; Grote, Anna-Karina; Kleigrewe, Karin; Humpf, Hans-Ulrich

2011-07-27

459

The Fourier transform spectrometer of the Universite? Pierre et Marie Curie QualAir platform.  

PubMed

A Bruker Optics IFS 125HR Fourier transform spectrometer (FTS) and the Laboratoire de Physique Mole?culaire pour l'Atmosphe?re et l'Astrophysique retrieval algorithm were adapted for ground based atmospheric measurements. As one of the major instruments of the experimental research platform QualAir, this FTS is dedicated to study the urban air composition of large megacity such as Paris. The precise concentration measurements of the most important atmospheric pollutants are a key to improve the understanding and modeling of urban air pollution processes. Located in the center of Paris, this remote sensing spectrometer enables to monitor many pollutants. Examples for NO(2) and CO are demonstrating the performances of this new experimental setup. PMID:21034070

Té, Y; Jeseck, P; Payan, S; Pépin, I; Camy-Peyret, C

2010-10-01

460

Voice Activity Detection in Noisy Environments Based on Double-Combined Fourier Transform and Line Fitting  

PubMed Central

A new voice activity detector for noisy environments is proposed. In conventional algorithms, the endpoint of speech is found by applying an edge detection filter that finds the abrupt changing point in a feature domain. However, since the frame energy feature is unstable in noisy environments, it is difficult to accurately find the endpoint of speech. Therefore, a novel feature extraction algorithm based on the double-combined Fourier transform and envelope line fitting is proposed. It is combined with an edge detection filter for effective detection of endpoints. Effectiveness of the proposed algorithm is evaluated and compared to other VAD algorithms using two different databases, which are AURORA 2.0 database and SITEC database. Experimental results show that the proposed algorithm performs well under a variety of noisy conditions. PMID:25170520

Park, Jinsoo; Kim, Wooil; Han, David K.; Ko, Hanseok

2014-01-01

461

Breast cancer detection from MR images through an auto-probing discrete Fourier transform system.  

PubMed

A computer-aided detection auto-probing (CADAP) system is presented for detecting breast lesions using dynamic contrast enhanced magnetic resonance imaging, through a spatial-based discrete Fourier transform. The stand-alone CADAP system reduces noise, refines region of interest (ROI) automatically, and detects the breast lesion with minimal false positive detection. The lesions are then classified and colourised according to their characteristics, whether benign, suspicious or malignant. To enhance the visualisation, the entire analysed ROI is constructed into a 3-D image, so that the user can diagnose based on multiple views on the ROI. The proposed method has been applied to 101 sets of digital images, and the results compared with the biopsy results done by radiologists. The proposed scheme is able to identify breast cancer regions accurately and efficiently. PMID:24736203

Sim, K S; Chia, F K; Nia, M E; Tso, C P; Chong, A K; Abbas, Siti Fathimah; Chong, S S

2014-06-01

462

Label-free identification of individual bacteria using Fourier transform light scattering  

E-print Network

Rapid identification of bacterial species is crucial in medicine and food hygiene. In order to achieve rapid and label-free identification of bacterial species at the single bacterium level, we propose and experimentally demonstrate an optical method based on Fourier transform light scattering (FTLS) measurements and statistical classification. For individual rod-shaped bacteria belonging to four bacterial species (Listeria monocytogenes, Escherichia coli, Lactobacillus casei, and Bacillus subtilis), two-dimensional angle-resolved light scattering maps are precisely measured using FTLS technique. The scattering maps are then systematically analyzed, employing statistical classification in order to extract the unique fingerprint patterns for each species, so that a new unidentified bacterium can be identified by a single light scattering measurement. The single-bacterial and label-free nature of our method suggests wide applicability for rapid point-of-care bacterial diagnosis.

Jo, YoungJu; Kim, Min-hyeok; Park, HyunJoo; Kang, Suk-Jo; Park, YongKeun

2015-01-01

463

Depth resolved hyperspectral imaging spectrometer based on structured light illumination and Fourier transform interferometry  

PubMed Central

A depth resolved hyperspectral imaging spectrometer can provide depth resolved imaging both in the spatial and the spectral domain. Images acquired through a standard imaging Fourier transform spectrometer do not have the depth-resolution. By post processing the spectral cubes (x, y, ?) obtained through a Sagnac interferometer under uniform illumination and structured illumination, spectrally resolved images with depth resolution can be recovered using structured light illumination algorithms such as the HiLo method. The proposed scheme is validated with in vitro specimens including fluorescent solution and fluorescent beads with known spectra. The system is further demonstrated in quantifying spectra from 3D resolved features in biological specimens. The system has demonstrated depth resolution of 1.8 ?m and spectral resolution of 7 nm respectively. PMID:25360367

Choi, Heejin; Wadduwage, Dushan; Matsudaira, Paul T.; So, Peter T.C.

2014-01-01

464

Complete quality analysis of commercial surface-active products by Fourier-transform near infrared spectroscopy.  

PubMed

Using proper calibration data Fourier-transform near infrared spectroscopy is used for developing multivariate calibrations for different analytical determinations routinely used in the surfactants industry. Four products were studied: oleyl-cetyl alcohol polyethoxylated, cocamidopropyl betaine (CAPB), sodium lauryl sulfate (SLS) and nonylphenol polyethoxylated (NPEO). Calibrations for major as well as very low concentrated compounds were achieved and every model was validated through linearity, bias, accuracy and precision tests, showing good results and the viability of NIR spectroscopy as a full quality control method for this products. Duplicate and complete analysis on a single sample takes at most 3min, requiring neither sample preparation nor the use of reagents. The analytical reference procedures involved in this work represent the typical ones used in the industry and the NIR method shows good results in the analysis of components with weight concentrations less than 1%. PMID:19073102

Martínez-Aguilar, Juan Fco; Ibarra-Montaño, Emma L

2007-10-15

465

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

NASA Astrophysics Data System (ADS)

Cryogenic deposition techniques for Gas Chromatography/Fourier Transform Infrared (GC/FT-IR) can be successfully employed in urinalysis for drugs of abuse with detection limits comparable to those of the established Gas Chromatography/Mass Spectrometry (GC/MS) technique. The additional confidence of the data that infrared analysis can offer has been helpful in identifying ambiguous results, particularly, in the case of amphetamines where drugs of abuse can be confused with over-the-counter medications or naturally occurring amines. Hair analysis has been important in drug testing when adulteration of urine samples has been a question. Functional group mapping can further assist the analysis and track drug use versus time.

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

1994-01-01

466

Epileptic seizure classification of EEG time-series using rational discrete short-time fourier transform.  

PubMed

A system for epileptic seizure detection in electroencephalography (EEG) is described in this paper. One of the challenges is to distinguish rhythmic discharges from nonstationary patterns occurring during seizures. The proposed approach is based on an adaptive and localized time-frequency representation of EEG signals by means of rational functions. The corresponding rational discrete short-time Fourier transform (DSTFT) is a novel feature extraction technique for epileptic EEG data. A multilayer perceptron classifier is fed by the coefficients of the rational DSTFT in order to separate seizure epochs from seizure-free epochs. The effectiveness of the proposed method is compared with several state-of-art feature extraction algorithms used in offline epileptic seizure detection. The results of the comparative evaluations show that the proposed method outperforms competing techniques in terms of classification accuracy. In addition, it provides a compact representation of EEG time-series. PMID:25265603

Samiee, Kaveh; Kovacs, Peter; Gabbouj, Moncef

2015-02-01

467

A Novel Application of Fourier Transform Spectroscopy with HEMT Amplifiers at Microwave Frequencies  

NASA Technical Reports Server (NTRS)

The goal was to develop cryogenic high-electron-mobility transistor (HEMT) based radiometers and use them to measure the anisotropy in the cosmic microwave background (CMB). In particular, a novel Fourier transform spectrometer (FTS) built entirely of waveguide components would be developed. A dual-polarization Ka-band HEMT radiometer and a similar Q-band radiometer were built. In a series of measurements spanning three years made from a ground-based site in Saskatoon, SK, the amplitude, frequency spectrum, and spatial frequency spectrum of the anisotropy were measured. A prototype Ka-band FTS was built and tested, and a simplified version is proposed for the MAP satellite mission. The 1/f characteristics of HEMT amplifiers were quantified using correlation techniques.

Wilkinson, David T.; Page, Lyman

1995-01-01

468

Mitochondrial Metabolomics Using High-Resolution Fourier-Transform Mass Spectrometry  

PubMed Central

Summary High-resolution Fourier-transform mass spectrometry (FTMS) provides important advantages in studies of metabolism because more than half of common intermediary metabolites can be measured in 10 min with minimal pre-detector separation and without ion-dissociation. This allows unprecedented opportunity to study complex metabolic systems, such as mitochondria. Analysis of mouse liver mitochondria using FTMS with liquid chromatography shows that sex and genotypic differences in mitochondrial metabolism can be readily distinguished. Additionally, differences in mitochondrial function are readily measured, and many of the mitochondria-related metabolites are also measurable in plasma. Thus, application of high-resolution mass spectrometry provides an approach for integrated studies of complex metabolic processes of mitochondrial function and dysfunction in disease. PMID:25270922

Go, Young-Mi; Uppal, Karan; Roede, James R.; Jones, Dean P.; Tran, ViLinh; Walker, Douglas I.; Dury, Lauriane; Strobel, Frederick H.; Baubichon-Cortay, Hélène; Pennell, Kurt D.

2015-01-01

469

Fourier Transform Raman Spectroscopy In The Near Infrared - Industrial Applications And Limitations  

NASA Astrophysics Data System (ADS)

In the past the application of Raman spectroscopy as an analytical tool has been severely restricted by laser induced fluorescence. It has been demonstrated recently 1,2, that near infrared Fourier Transform Raman spectroscopy can offer a solution to this problem. Near infrared laser excitation energy is, in general, too low to excite fluorescence. Unfortunately, the scattered Raman intensity is inversely proportional to the fourth power of the wavelength. This leads to a reduction in intensity of a factor of 22 on moving from 514.5 nm to 1064.1 nm excitation. Also, near infrared detectors are orders of magnitude less sensitive than photomultipliers used in conventional Raman spectroscopy. Despite these restrictions the FT-Raman technique opens up new possibilities for Raman spectroscopy.

Shurvell, H. F.; Bergin, F. J.

1989-12-01

470

Fourier transform two-dimensional fluorescence excitation spectrometer by using tandem Fabry-Pérot interferometer  

NASA Astrophysics Data System (ADS)

A Fourier transform two-dimensional fluorescence excitation spectrometer (FT-2DFES) was developed based on the multiplex technique using a tandem Fabry-Pérot interferometer (tandem FPI). In addition to the advantage of the multiplex technique, the main advantage of the tandem FPI is applicable to the modulation of transition with a large absorption bandwidth (larger than 100 nm) and is thus applicable to the modulation of the excitation of molecules in the condensed phase. As a demonstration of the effectiveness of FT-2DFES, we succeeded in separately observing the fluorescence excitation peaks from a mixed methanol solution of laser dyes (coumarin 480, rhodamine 6G, DCM (4-dicyanomethylene-2-methyl-6-(p-(dimethylamino)styryl)-4H-pyran), and LDS750). Furthermore, the energy transfer from rhodamine 6G to LDS750 was observed.

Anzai, Hiroshi; Joshi, Neeraj Kumar; Fuyuki, Masanori; Wada, Akihide

2015-01-01

471

Fourier transform ion cyclotron resonance (FT ICR) mass spectrometry: Theory and simulations.  

PubMed

Fourier transform ion cyclotron resonance (FT ICR) mass spectrometer offers highest resolving power and mass accuracy among all types of mass spectrometers. Its unique analytical characteristics made FT ICR important tool for proteomics, metabolomics, petroleomics, and investigation of complex mixtures. Signal acquisition in FT ICR MS takes long time (up to minutes). During this time ion-ion interaction considerably affects ion motion and result in decreasing of the resolving power. Understanding of those effects required complicated theory and supercomputer simulations but culminated in the invention of the ion trap with dynamic harmonization which demonstrated the highest resolving power ever achieved. In this review we summarize latest achievements in theory and simulation of FT ICR mass spectrometers. © 2014 Wiley Periodicals, Inc. Mass Spec Rev. PMID:24515872

Nikolaev, Eugene N; Kostyukevich, Yury I; Vladimirov, Gleb N

2014-02-10

472

[Application of Fourier transform attenuated total reflection infrared spectroscopy in analysis of pulp and paper industry].  

PubMed

As one of the most powerful tools to investigate the compositions of raw materials and the property of pulp and paper, infrared spectroscopy has played an important role in pulp and paper industry. However, the traditional transmission infrared spectroscopy has not met the requirements of the producing processes because of its disadvantages of time consuming and sample destruction. New technique would be needed to be found. Fourier transform attenuated total reflection infrared spectroscopy (ATR-FTIR) is an advanced spectroscopic tool for nondestructive evaluation and could rapidly, accurately estimate the production properties of each process in pulp and paper industry. The present review describes the application of ATR-FTIR in analysis of pulp and paper industry. The analysis processes will include: pulping, papermaking, environmental protecting, special processing and paper identifying. PMID:21595211

Zhang, Yong; Cao, Chun-yu; Feng, Wen-ying; Xu, Ming; Su, Zhen-hua; Liu, Xiao-meng; Lü, Wei-jun

2011-03-01

473

Fourier transform infrared identification of the ?5(?u) fundamental of SiC5Si.  

PubMed

The Fourier transform infrared spectrum of SiC5Si was observed by trapping the vapor from the Nd:YAG laser ablation of sintered Si/C rods in solid Ar at ?20 K. Measurements of (13)C and (29,30)Si isotopic shifts have enabled the identification of the ?5(?u) vibrational fundamental of the linear isomer of SiC5Si at 1590.8 ± 0.2 cm(-1). The results are in excellent agreement with the predictions of density functional theory calculations at the B3LYP/cc-pVDZ level. A second fundamental, ?4(?u), can only be tentatively identified at 2021.0 cm(-1), because its isotopic shifts are overlapped by absorptions from other species. PMID:25084918

Lê, T H; Rittby, C M L; Graham, W R M

2014-07-28

474

[Spectral baseline correction by piecewise dividing in Fourier transform infrared gas analysis].  

PubMed

Aimed at the problem that baseline drift or distortion often appears in Fourier transform spectra after spectrometer has continuously worked for a long time, baseline variation caused by IR source temperature drift and fluctuation, tilt of moving mirror, performance parameter change of beam splitter and lateral shift of detector were studied by simulating using MATLAB. Simulation results show that spectral baseline drift is approximately linear. On this basis, a novel method named spectral baseline correction by piecewise dividing (SBCPD) is proposed to correct spectral baseline in the present work By comparing peak height of simulated spectra, it was found that performance of SBCPD is better than that of common methods of polynomial fitting, air-PLS (adaptive iteratively reweighted Penalized Least Squares). And the application in gas well-logging showed that prediction accuracy of SBCPD is also higher. Additionally, this method is reliable and of less calculation, and is suitable for engineering application. PMID:23697106

Tang, Xiao-Jun; Wang, Jin; Zhang, Lei; Guan, Jin-Feng; Zhang, Yong; Liu, Jun-Hua

2013-02-01

475

Fourier Transform Emission Spectroscopy of the Visible Transitions of AuCl.  

PubMed

The visible electronic transitions of AuCl were observed at high resolution for the first time. The spectrum was recorded with the Fourier transform spectrometer associated with the McMath-Pierce solar telescope at Kitt Peak. The excited AuCl molecules were produced in a microwave discharge, with 4 Torr of helium seeded with 3% chlorine flowing over AuCl3 powder. Constants for the X1Sigma+, AOmega = 1, and BOmega = 0(+) states of Au35Cl are presented. The AOmega = 1 and the BOmega = 0(+) states may be two spin-orbit components of a 3Pi electronic state, and molecular parameters for this excited 3Pi state also are given. Copyright 1999 Academic Press. PMID:9986781

O'brien; Elliott; Dulick

1999-03-01

476

Gastric cancer differentiation using Fourier transform near-infrared spectroscopy with unsupervised pattern recognition  

NASA Astrophysics Data System (ADS)

The manuscript has investigated the application of near-infrared (NIR) spectroscopy for differentiation gastric cancer. The 90 spectra from cancerous and normal tissues were collected from a total of 30 surgical specimens using Fourier transform near-infrared spectroscopy (FT-NIR) equipped with a fiber-optic probe. Major spectral differences were observed in the CH-stretching second overtone (9000-7000 cm-1), CH-stretching first overtone (6000-5200 cm-1), and CH-stretching combination (4500-4000 cm-1) regions. By use of unsupervised pattern recognition, such as principal component analysis (PCA) and cluster analysis (CA), all spectra were classified into cancerous and normal tissue groups with accuracy up to 81.1%. The sensitivity and specificity was 100% and 68.2%, respectively. These present results indicate that CH-stretching first, combination band and second overtone regions can serve as diagnostic markers for gastric cancer.

Yi, Wei-song; Cui, Dian-sheng; Li, Zhi; Wu, Lan-lan; Shen, Ai-guo; Hu, Ji-ming

2013-01-01

477

Astigmatism error modification for absolute shape reconstruction using Fourier transform method  

NASA Astrophysics Data System (ADS)

A method is proposed to modify astigmatism errors in absolute shape reconstruction of optical plane using Fourier transform method. If a transmission and reflection flat are used in an absolute test, two translation measurements lead to obtain the absolute shapes by making use of the characteristic relationship between the differential and original shapes in spatial frequency domain. However, because the translation device cannot guarantee the test and reference flats rigidly parallel to each other after the translations, a tilt error exists in the obtained differential data, which caused power and astigmatism errors in the reconstructed shapes. In order to modify the astigmatism errors, a rotation measurement is added. Based on the rotation invariability of the form of Zernike polynomial in circular domain, the astigmatism terms are calculated by solving polynomial coefficient equations related to the rotation differential data, and subsequently the astigmatism terms including error are modified. Computer simulation proves the validity of the proposed method.

He, Yuhang; Li, Qiang; Gao, Bo; Liu, Ang; Xu, Kaiyuan; Wei, Xiaohong; Chai, Liqun

2014-12-01

478