NASA Technical Reports Server (NTRS)
Shertzer, Janine; Temkin, Aaron
2004-01-01
The development of a practical method of accurately calculating the full scattering amplitude, without making a partial wave decomposition is continued. The method is developed in the context of electron-hydrogen scattering, and here exchange is dealt with by considering e-H scattering in the static exchange approximation. The Schroedinger equation in this approximation can be simplified to a set of coupled integro-differential equations. The equations are solved numerically for the full scattering wave function. The scattering amplitude can most accurately be calculated from an integral expression for the amplitude; that integral can be formally simplified, and then evaluated using the numerically determined wave function. The results are essentially identical to converged partial wave results.
Partial-wave decomposition of the finite-range effective tensor interaction
NASA Astrophysics Data System (ADS)
Davesne, D.; Becker, P.; Pastore, A.; Navarro, J.
2016-06-01
We perform a detailed analysis of the properties of the finite-range tensor term associated with the Gogny and M3Y effective interactions. In particular, by using a partial-wave decomposition of the equation of state of symmetric nuclear matter, we show how we can extract their tensor parameters directly from microscopic results based on bare nucleon-nucleon interactions. Furthermore, we show that the zero-range limit of both finite-range interactions has the form of the next-to-next-to-next-leading-order (N3LO) Skyrme pseudopotential, which thus constitutes a reliable approximation in the density range relevant for finite nuclei. Finally, we use Brueckner-Hartree-Fock results to fix the tensor parameters for the three effective interactions.
NASA Technical Reports Server (NTRS)
Shertzer, Janine; Temkin, Aaron
2007-01-01
In the first two papers in this series, we developed a method for studying electron-hydrogen scattering that does not use partial wave analysis. We constructed an ansatz for the wave function in both the static and static exchange approximations and calculated the full scattering amplitude. Here we go beyond the static exchange approximation, and include correlation in the wave function via a modified polarized orbital. This correlation function provides a significant improvement over the static exchange approximation: the resultant elastic scattering amplitudes are in very good agreement with fully converged partial wave calculations for electron-hydrogen scattering. A fully variational modification of this approach is discussed in the conclusion of the article Popular summary of Direct calculation of the scattering amplitude without partial wave expansion. III ....." by J. Shertzer and A. Temkin. In this paper we continue the development of In this paper we continue the development of a new approach to the way in which researchers have traditionally used to calculate the scattering cross section of (low-energy) electrons from atoms. The basic mathematical problem is to solve the Schroedinger Equation (SE) corresponding the above physical process. Traditionally it was always the case that the SE was reduced to a sequence of one-dimensional (ordinary) differential equations - called partial waves which were solved and from the solutions "phase shifts" were extracted, from which the scattering cross section was calculated.
NASA Astrophysics Data System (ADS)
Kuruoğlu, Zeki C.
2014-01-01
Recently there has been a growing interest in computational methods for quantum scattering equations that avoid the traditional decomposition of wave functions and scattering amplitudes into partial waves. The aim of the present work is to show that the weighted-residual approach in combination with local basis functions give rise to convenient computational schemes for the solution of the multi-variable integral equations without the partial wave expansion. The weighted-residual approach provides a unifying framework for various variational and degenerate-kernel methods for integral equations of scattering theory. Using a direct-product basis of localized quadratic interpolation polynomials, Galerkin, collocation and Schwinger variational realizations of the weighted-residual approach have been implemented for a model potential. It is demonstrated that, for a given expansion basis, Schwinger variational method exhibits better convergence with basis size than Galerkin and collocation methods. A novel hybrid-collocation method is implemented with promising results as well.
Calculation of the Full Scattering Amplitude without Partial Wave Decomposition II
NASA Technical Reports Server (NTRS)
Shertzer, J.; Temkin, A.
2003-01-01
As is well known, the full scattering amplitude can be expressed as an integral involving the complete scattering wave function. We have shown that the integral can be simplified and used in a practical way. Initial application to electron-hydrogen scattering without exchange was highly successful. The Schrodinger equation (SE) can be reduced to a 2d partial differential equation (pde), and was solved using the finite element method. We have now included exchange by solving the resultant SE, in the static exchange approximation. The resultant equation can be reduced to a pair of coupled pde's, to which the finite element method can still be applied. The resultant scattering amplitudes, both singlet and triplet, as a function of angle can be calculated for various energies. The results are in excellent agreement with converged partial wave results.
NASA Technical Reports Server (NTRS)
Shertzer, Janine; Temkin, A.
2003-01-01
As is well known, the full scattering amplitude can be expressed as an integral involving the complete scattering wave function. We have shown that the integral can be simplified and used in a practical way. Initial application to electron-hydrogen scattering without exchange was highly successful. The Schrodinger equation (SE), which can be reduced to a 2d partial differential equation (pde), was solved using the finite element method. We have now included exchange by solving the resultant SE, in the static exchange approximation, which is reducible to a pair of coupled pde's. The resultant scattering amplitudes, both singlet and triplet, calculated as a function of energy are in excellent agreement with converged partial wave results.
Solution of the Bethe-Goldstone equation without partial wave decomposition
NASA Astrophysics Data System (ADS)
White, Larz
Nucleon-nucleon scattering is a most fundamental process in nuclear physics. From the theoretical standpoint, its description in momentum space involves the solution of an integral equation in three dimensions, which is typically accomplished with the help of a partial wave expansion of the scattering amplitude. It is the purpose of this work to present a method for solving the nucleon-nucleon scattering equation without the use of such expansion. After verifying the accuracy of our numerical tools by comparing with existing solutions of the nucleon-nucleon scattering amplitude in free space, we proceed to apply the method to the equation describing scattering of two nucleons in the nuclear medium, known as the Bethe-Goldstone equation. An important feature of this equation is the presence of the so-called "Pauli blocking operator", which prevents scattering of two fermions into occupied states, as required by the Pauli principle. In standard solution methods based on partial wave expansions, it is necessary to apply an approximation to this operator, which involves averaging over angular variables and is therefore known as the "spherical approximation". In our method, this approximation can be avoided. Thus, a focal point of this study is a comparison of Pauli blocking effects calculated in the (angle-dependent) three-dimensional formalism as compared to the usual spherical approximation. We present results for nucleon-nucleon amplitudes and observables and discuss their implications.
Coherent-mode decomposition of partially polarized, partially coherent sources
NASA Astrophysics Data System (ADS)
Gori, Franco; Santarsiero, Massimo; Simon, Raja; Piquero, Gemma; Borghi, Riccardo; Guattari, Giorgio
2003-01-01
It is shown that any partially polarized, partially coherent source can be expressed in terms of a suitable superposition of transverse coherent modes with orthogonal polarization states. Such modes are determined through the solution of a system of two coupled integral equations. An example, for which the modal decomposition is obtained in closed form in terms of fully linearly polarized Hermite Gaussian modes, is given.
Coherent-mode decomposition of partially polarized, partially coherent sources.
Gori, Franco; Santarsiero, Massimo; Simon, Raja; Piquero, Gemma; Borghi, Riccardo; Guattari, Giorgio
2003-01-01
It is shown that any partially polarized, partially coherent source can be expressed in terms of a suitable superposition of transverse coherent modes with orthogonal polarization states. Such modes are determined through the solution of a system of two coupled integral equations. An example, for which the modal decomposition is obtained in closed form in terms of fully linearly polarized Hermite Gaussian modes, is given. PMID:12542320
Are Electron Partial Waves Real
NASA Astrophysics Data System (ADS)
Yenen, O.; McLaughlin, K. W.
2005-05-01
Experiments determining the partial wave content of electrons are uncommon. The standard approach to partial wave expansion of the wavefunction of electrons often ignores their spin. In this non-relativistic approximation the partial waves are labeled by their orbital angular momentum quantum number, e.g. d-waves. As our previous work has shown, this non-relativistic approximation usually fails for photoelectrons. Partial waves should be further specified by their total angular momentum. With d-waves for example, one would need to distinguish between d3/2 and d5/2 partial waves. Although energetically degenerate, fully relativistic d3/2 and d5/2 partial waves of photoelectrons have fundamentally different angular distributions. Using experimental and theoretical methods we have developed, we obtain partial wave probabilities of photoelectrons from polarization measurements of ionic fluorescence. We found that for selected states of the residual ion, there are energy regions where the photoelectron is in a single partial wave with predictable angular distributions.
How to Compute the Partial Fraction Decomposition without Really Trying
ERIC Educational Resources Information Center
Brazier, Richard; Boman, Eugene
2007-01-01
For various reasons there has been a recent trend in college and high school calculus courses to de-emphasize teaching the Partial Fraction Decomposition (PFD) as an integration technique. This is regrettable because the Partial Fraction Decomposition is considerably more than an integration technique. It is, in fact, a general purpose tool which…
Remarks on the travelling wave decomposition
Pollitz, F.F.
2001-01-01
In elastic wave propagation on a spherically symmetric earth model, a normal mode sum is converted into a sum of equivalent travelling waves by means of a travelling wave decomposition (TWD). For two decades, seismologists have assumed that each travelling wave in the TWD is associated with only real phase velocities, that is, no evanescent waves travel on a spherically symmetric earth model. In this paper, this assumption is proven false. By including a countably infinite set of waves travelling as evanescent waves, several conceptual difficulties confronting the TWD are resolved.
Holographic conformal partial waves as gravitational open Wilson networks
NASA Astrophysics Data System (ADS)
Bhatta, Atanu; Raman, Prashanth; Suryanarayana, Nemani V.
2016-06-01
We propose a method to holographically compute the conformal partial waves in any decomposition of correlation functions of primary operators in conformal field theories using open Wilson network operators in the holographic gravitational dual. The Wilson operators are the gravitational ones where gravity is written as a gauge theory in the first order Hilbert-Palatini formalism. We apply this method to compute the global conformal blocks and partial waves in 2d CFTs reproducing many of the known results.
Pseudopotential Method for Higher Partial Wave Scattering
Idziaszek, Zbigniew; Calarco, Tommaso
2006-01-13
We present a zero-range pseudopotential applicable for all partial wave interactions between neutral atoms. For p and d waves, we derive effective pseudopotentials, which are useful for problems involving anisotropic external potentials. Finally, we consider two nontrivial applications of the p-wave pseudopotential: we solve analytically the problem of two interacting spin-polarized fermions confined in a harmonic trap, and we analyze the scattering of p-wave interacting particles in a quasi-two-dimensional system.
Partial wave analysis using graphics processing units
NASA Astrophysics Data System (ADS)
Berger, Niklaus; Beijiang, Liu; Jike, Wang
2010-04-01
Partial wave analysis is an important tool for determining resonance properties in hadron spectroscopy. For large data samples however, the un-binned likelihood fits employed are computationally very expensive. At the Beijing Spectrometer (BES) III experiment, an increase in statistics compared to earlier experiments of up to two orders of magnitude is expected. In order to allow for a timely analysis of these datasets, additional computing power with short turnover times has to be made available. It turns out that graphics processing units (GPUs) originally developed for 3D computer games have an architecture of massively parallel single instruction multiple data floating point units that is almost ideally suited for the algorithms employed in partial wave analysis. We have implemented a framework for tensor manipulation and partial wave fits called GPUPWA. The user writes a program in pure C++ whilst the GPUPWA classes handle computations on the GPU, memory transfers, caching and other technical details. In conjunction with a recent graphics processor, the framework provides a speed-up of the partial wave fit by more than two orders of magnitude compared to legacy FORTRAN code.
Chemical decomposition by normalization of millimeter-wave spectra
Gopalan, K.; Gopalsami, N.
1996-10-01
The sharp, distinct absorption spectra of chemicals at low pressures in the mm wave range become broadened at high pressures, so that detecting and quantifying different chemicals at high pressures become difficult. This paper proposes a method of decomposition based on the low pressure spectra. Normalized low pressure spectral amplitudes are used as features to train a neural network. The network is tested using the peak spectra obtained for an unknown plume of chemicals at high pressure. Initial tests conducted on simulated and experimental spectra of selected chemicals show that the decomposition results of the proposed method are dependent on the dominance of the chemicals in the mixture - a characteristic common to conventional methods of decomposition.
Algebraic decomposition of the TU wave morphology patterns.
Padrini, R; Butrous, G; Camm, A J; Malik, M
1995-12-01
In principle, the T wave results from the differences in durations of action potentials (AP) of different ventricular regions. Based on this concept, a mathematical model has been developed that represents the TU wave morphology as a summation of four AP-like functions: TU = S1 - S2 + L1 - L2. The sigmoidal shape of AP-like curves is produced by Hill's equation V(t) = a . tn/(bn + tn). Each of the decomposition functions is characterized by two parameters: the amplitude at the beginning of QRS (Amax), and the duration at 5% of Amax (D95). The set of four decomposition functions leads to eight parameters that provide detailed characteristics of the TU wave morphology. The model was validated using 170 TU wave complexes recorded digitally in leads V2-V6 from 22 normal subjects and 12 patients with abnormal TU wave morphologies (negative, biphasic, and notched T waves). The electrocardiographic signals were sampled at 100 Hz and a best-fit procedure was used to obtain the decomposition. In all cases the coefficients of correlation between original TU patterns and their mathematical models were > or = 0.99. The mean absolute difference between the observed and modeled values of the TU patterns was similar in cases with normal and abnormal TU wave morphologies (4.65 +/- 0.41 microV vs 5.19 +/- 0.48 microV respectively) demonstrating that the model is capable of describing and categorizing various TU patterns by a set of eight numerical parameters. PMID:8771134
Gaussian beam decomposition of high frequency wave fields
Tanushev, Nicolay M. Engquist, Bjoern; Tsai, Richard
2009-12-10
In this paper, we present a method of decomposing a highly oscillatory wave field into a sparse superposition of Gaussian beams. The goal is to extract the necessary parameters for a Gaussian beam superposition from this wave field, so that further evolution of the high frequency waves can be computed by the method of Gaussian beams. The methodology is described for R{sup d} with numerical examples for d=2. In the first example, a field generated by an interface reflection of Gaussian beams is decomposed into a superposition of Gaussian beams. The beam parameters are reconstructed to a very high accuracy. The data in the second example is not a superposition of a finite number of Gaussian beams. The wave field to be approximated is generated by a finite difference method for a geometry with two slits. The accuracy in the decomposition increases monotonically with the number of beams.
Partial Wave Analysis of Coupled Photonic Structures
NASA Technical Reports Server (NTRS)
Fuller, Kirk A.; Smith, David D.; Curreri, Peter A. (Technical Monitor)
2002-01-01
The very high quality factors sustained by microcavity optical resonators are relevant to applications in wavelength filtering, routing, switching, modulation, and multiplexing/demultiplexing. Increases in the density of photonic elements require that attention be paid to how electromagnetic (EM) coupling modifies their optical properties. This is especially true when cavity resonances are involved, in which case, their characteristics may be fundamentally altered. Understanding the optical properties of microcavities that are near or in contact with photonic elements---such as other microcavities, nanostructures, couplers, and substrates---can be expected to advance our understanding of the roles that these structures may play in VLSI photonics, biosensors and similar device technologies. Wc present results from recent theoretical studies of the effects of inter- and intracavity coupling on optical resonances in compound spherical particles. Concentrically stratified spheres and bispheres constituted from homogeneous and stratified spheres are subjects of this investigation. A new formulation is introduced for the absorption of light in an arbitrary layer of a multilayered sphere, which is based on multiple reflections of the spherical partial waves of the Lorenz-Mie solution for scattering by a sphere. Absorption efficiencies, which can be used to profile cavity resonances and to infer fluorescence yields or the onset of nonlinear optical processes in the microcavities, are presented. Splitting of resonances in these multisphere systems is paid particular attention, and consequences for photonic device development and possible performance enhancements through carefully designed architectures that exploit EM coupling are considered.
Spin-orbit decomposition of ab initio nuclear wave functions
NASA Astrophysics Data System (ADS)
Johnson, Calvin W.
2015-03-01
Although the modern shell-model picture of atomic nuclei is built from single-particle orbits with good total angular momentum j , leading to j -j coupling, decades ago phenomenological models suggested that a simpler picture for 0 p -shell nuclides can be realized via coupling of the total spin S and total orbital angular momentum L . I revisit this idea with large-basis, no-core shell-model calculations using modern ab initio two-body interactions and dissect the resulting wave functions into their component L - and S -components. Remarkably, there is broad agreement with calculations using the phenomenological Cohen-Kurath forces, despite a gap of nearly 50 years and six orders of magnitude in basis dimensions. I suggest that L -S decomposition may be a useful tool for analyzing ab initio wave functions of light nuclei, for example, in the case of rotational bands.
ERIC Educational Resources Information Center
Man, Yiu-Kwong
2012-01-01
In this note, a new method for computing the partial fraction decomposition of rational functions with irreducible quadratic factors in the denominators is presented. This method involves polynomial divisions and substitutions only, without having to solve for the complex roots of the irreducible quadratic polynomial or to solve a system of linear…
Asymmetric modes decomposition in an overmoded relativistic backward wave oscillator
Zhang, Dian; Zhang, Jun Zhong, Huihuang; Jin, Zhenxing; Ju, Jinchuan
2014-09-15
Most of the investigated overmoded relativistic backward wave oscillators (RBWOs) are azimuthally symmetric; thus, they are designed through two dimensional (2-D) particle-in-cell (PIC) simulations. However, 2-D PIC simulations cannot reveal the effect of asymmetric modes on beam-wave interaction. In order to investigate whether asymmetric mode competition needs to be considered in the design of overmoded RBWOs, a numerical method of determining the composition of both symmetric and asymmetric modes in three dimensional (3-D) PIC simulations is introduced in this paper. The 2-D and 3-D PIC simulation results of an X-band overmoded RBWO are analyzed. Our analysis indicates that the 2-D and 3-D PIC simulation results of our device are quite different due to asymmetric mode competition. In fact, asymmetric surface waves, especially EH{sub 11} mode, can lead to serious mode competition when electron beam propagates near the surface of slow wave structures (SWSs). Therefore, additional method of suppressing asymmetric mode competition, such as adjusting the reflections at both ends of SWSs to decrease the Q-factor of asymmetric modes, needs to be utilized in the design of overmoded RBWOs. Besides, 3-D PIC simulation and modes decomposition are essential for designing overmoded RBWOs.
ERIC Educational Resources Information Center
Man, Yiu-Kwong
2012-01-01
Partial fraction decomposition is a useful technique often taught at senior secondary or undergraduate levels to handle integrations, inverse Laplace transforms or linear ordinary differential equations, etc. In recent years, an improved Heaviside's approach to partial fraction decomposition was introduced and developed by the author. An important…
Plane-wave decomposition by spherical-convolution microphone array
NASA Astrophysics Data System (ADS)
Rafaely, Boaz; Park, Munhum
2001-05-01
Reverberant sound fields are widely studied, as they have a significant influence on the acoustic performance of enclosures in a variety of applications. For example, the intelligibility of speech in lecture rooms, the quality of music in auditoria, the noise level in offices, and the production of 3D sound in living rooms are all affected by the enclosed sound field. These sound fields are typically studied through frequency response measurements or statistical measures such as reverberation time, which do not provide detailed spatial information. The aim of the work presented in this seminar is the detailed analysis of reverberant sound fields. A measurement and analysis system based on acoustic theory and signal processing, designed around a spherical microphone array, is presented. Detailed analysis is achieved by decomposition of the sound field into waves, using spherical Fourier transform and spherical convolution. The presentation will include theoretical review, simulation studies, and initial experimental results.
Zhang, Xiaoxing; Liu, Heng; Ren, Jiangbo; Li, Jian; Li, Xin
2015-02-01
Gas-insulated switchgear (GIS) internal SF6 gas produces specific decomposition components under partial discharge (PD). By detecting these characteristic decomposition components, such information as the type and level of GIS internal insulation deterioration can be obtained effectively, and the status of GIS internal insulation can be evaluated. SF6 was selected as the background gas for Fourier transform infrared spectroscopy (FTIR) detection in this study. SOF2, SO2F2, SO2, and CO were selected as the characteristic decomposition components for system analysis. The standard infrared absorption spectroscopy of the four characteristic components was measured, the optimal absorption peaks were recorded and the corresponding absorption coefficient was calculated. Quantitative detection experiments on the four characteristic components were conducted. The volume fraction variation trend of four characteristic components at different PD time were analyzed. And under five different PD quantity, the quantitative relationships among gas production rate, PD time, and PD quantity were studied. PMID:25459612
NASA Astrophysics Data System (ADS)
Zhang, Xiaoxing; Liu, Heng; Ren, Jiangbo; Li, Jian; Li, Xin
2015-02-01
Gas-insulated switchgear (GIS) internal SF6 gas produces specific decomposition components under partial discharge (PD). By detecting these characteristic decomposition components, such information as the type and level of GIS internal insulation deterioration can be obtained effectively, and the status of GIS internal insulation can be evaluated. SF6 was selected as the background gas for Fourier transform infrared spectroscopy (FTIR) detection in this study. SOF2, SO2F2, SO2, and CO were selected as the characteristic decomposition components for system analysis. The standard infrared absorption spectroscopy of the four characteristic components was measured, the optimal absorption peaks were recorded and the corresponding absorption coefficient was calculated. Quantitative detection experiments on the four characteristic components were conducted. The volume fraction variation trend of four characteristic components at different PD time were analyzed. And under five different PD quantity, the quantitative relationships among gas production rate, PD time, and PD quantity were studied.
NASA Astrophysics Data System (ADS)
Gui, Yingang; Zhang, Xiaoxing; Zhang, Ying; Qiu, Yinjun; Chen, Lincong
2016-07-01
Air-insulated switchgear cabinet plays a critical role in entire power transmission and distribution system. Its stability directly affects the operational reliability of the power system. And the on-line gas detection method, which evaluates the insulation status of insulation equipment by detecting the decomposition components of filled air in cabinet, becomes an innovative way to ensure the running stability of air-insulated switchgear cabinet. In order to study the characteristic gas types and production regularity of decomposition components under partial discharge, three insulation defects: needle-plate, air-gap and impurity defect are proposed to simulate the insulation defects under partial discharge in air-insulated switchgear cabinet. Firstly, the generation pathways and mechanism of composition components are discussed. Then CO and NO2 are selected as the characteristic decomposition components to characterize the partial discharge due to their high concentration and chemical stability. Based on the different change regularity of CO and NO2 concentration under different insulation defect, it provides an effective way to evaluate and predict the insulation defect type and severity in the field.
Partial Wave Dispersion Relations: Application to Electron-Atom Scattering
NASA Technical Reports Server (NTRS)
Temkin, A.; Drachman, Richard J.
1999-01-01
In this Letter we propose the use of partial wave dispersion relations (DR's) as the way of solving the long-standing problem of correctly incorporating exchange in a valid DR for electron-atom scattering. In particular a method is given for effectively calculating the contribution of the discontinuity and/or poles of the partial wave amplitude which occur in the negative E plane. The method is successfully tested in three cases: (i) the analytically solvable exponential potential, (ii) the Hartree potential, and (iii) the S-wave exchange approximation for electron-hydrogen scattering.
ALFVEN WAVES IN A PARTIALLY IONIZED TWO-FLUID PLASMA
Soler, R.; Ballester, J. L.; Terradas, J.; Carbonell, M. E-mail: joseluis.ballester@uib.es E-mail: marc.carbonell@uib.es
2013-04-20
Alfven waves are a particular class of magnetohydrodynamic waves relevant in many astrophysical and laboratory plasmas. In partially ionized plasmas the dynamics of Alfven waves is affected by the interaction between ionized and neutral species. Here we study Alfven waves in a partially ionized plasma from the theoretical point of view using the two-fluid description. We consider that the plasma is composed of an ion-electron fluid and a neutral fluid, which interact by means of particle collisions. To keep our investigation as general as possible, we take the neutral-ion collision frequency and the ionization degree as free parameters. First, we perform a normal mode analysis. We find the modification due to neutral-ion collisions of the wave frequencies and study the temporal and spatial attenuation of the waves. In addition, we discuss the presence of cutoff values of the wavelength that constrain the existence of oscillatory standing waves in weakly ionized plasmas. Later, we go beyond the normal mode approach and solve the initial-value problem in order to study the time-dependent evolution of the wave perturbations in the two fluids. An application to Alfven waves in the low solar atmospheric plasma is performed and the implication of partial ionization for the energy flux is discussed.
MAGNETOACOUSTIC WAVES IN A PARTIALLY IONIZED TWO-FLUID PLASMA
Soler, Roberto; Ballester, Jose Luis; Carbonell, Marc E-mail: joseluis.ballester@uib.es
2013-11-01
Compressible disturbances propagate in a plasma in the form of magnetoacoustic waves driven by both gas pressure and magnetic forces. In partially ionized plasmas the dynamics of ionized and neutral species are coupled due to ion-neutral collisions. As a consequence, magnetoacoustic waves propagating through a partially ionized medium are affected by ion-neutral coupling. The degree to which the behavior of the classic waves is modified depends on the physical properties of the various species and on the relative value of the wave frequency compared to the ion-neutral collision frequency. Here, we perform a comprehensive theoretical investigation of magnetoacoustic wave propagation in a partially ionized plasma using the two-fluid formalism. We consider an extensive range of values for the collision frequency, ionization ratio, and plasma β, so that the results are applicable to a wide variety of astrophysical plasmas. We determine the modification of the wave frequencies and study the frictional damping due to ion-neutral collisions. Approximate analytic expressions for the frequencies are given in the limit case of strongly coupled ions and neutrals, while numerically obtained dispersion diagrams are provided for arbitrary collision frequencies. In addition, we discuss the presence of cutoffs in the dispersion diagrams that constrain wave propagation for certain combinations of parameters. A specific application to propagation of compressible waves in the solar chromosphere is given.
Lee, Jong-In; Kim, Young-Taek; Shin, Sungwon
2014-01-01
This study presents wave height distribution in terms of stem wave evolution phenomena on partially perforated wall structures through three-dimensional laboratory experiments. The plain and partially perforated walls were tested to understand their effects on the stem wave evolution under the monochromatic and random wave cases with the various wave conditions, incident angle (from 10 to 40 degrees), and configurations of front and side walls. The partially perforated wall reduced the relative wave heights more effectively compared to the plain wall structure. Partially perforated walls with side walls showed a better performance in terms of wave height reduction compared to the structure without the side wall. Moreover, the relative wave heights along the wall were relatively small when the relative chamber width is large, within the range of the chamber width in this study. The wave spectra showed a frequency dependency of the wave energy dissipation. In most cases, the existence of side wall is a more important factor than the porosity of the front wall in terms of the wave height reduction even if the partially perforated wall was still effective compared to the plain wall. PMID:25254260
Lee, Jong-In; Kim, Young-Taek; Shin, Sungwon
2014-01-01
This study presents wave height distribution in terms of stem wave evolution phenomena on partially perforated wall structures through three-dimensional laboratory experiments. The plain and partially perforated walls were tested to understand their effects on the stem wave evolution under the monochromatic and random wave cases with the various wave conditions, incident angle (from 10 to 40 degrees), and configurations of front and side walls. The partially perforated wall reduced the relative wave heights more effectively compared to the plain wall structure. Partially perforated walls with side walls showed a better performance in terms of wave height reduction compared to the structure without the side wall. Moreover, the relative wave heights along the wall were relatively small when the relative chamber width is large, within the range of the chamber width in this study. The wave spectra showed a frequency dependency of the wave energy dissipation. In most cases, the existence of side wall is a more important factor than the porosity of the front wall in terms of the wave height reduction even if the partially perforated wall was still effective compared to the plain wall. PMID:25254260
Correlations of πN partial waves for multireaction analyses
Doring, M.; Revier, J.; Ronchen, D.; Workman, R. L.
2016-06-15
In the search for missing baryonic resonances, many analyses include data from a variety of pion- and photon-induced reactions. For elastic πN scattering, however, usually the partial waves of the SAID (Scattering Analysis Interactive Database) or other groups are fitted, instead of data. We provide the partial-wave covariance matrices needed to perform correlated χ2 fits, in which the obtained χ2 equals the actual χ2 up to nonlinear and normalization corrections. For any analysis relying on partial waves extracted from elastic pion scattering, this is a prerequisite to assess the significance of resonance signals and to assign any uncertainty on results.more » Lastly, the influence of systematic errors is also considered.« less
Correlations of π N partial waves for multireaction analyses
NASA Astrophysics Data System (ADS)
Döring, M.; Revier, J.; Rönchen, D.; Workman, R. L.
2016-06-01
In the search for missing baryonic resonances, many analyses include data from a variety of pion- and photon-induced reactions. For elastic π N scattering, however, usually the partial waves of the SAID (Scattering Analysis Interactive Database) or other groups are fitted, instead of data. We provide the partial-wave covariance matrices needed to perform correlated χ2 fits, in which the obtained χ2 equals the actual χ2 up to nonlinear and normalization corrections. For any analysis relying on partial waves extracted from elastic pion scattering, this is a prerequisite to assess the significance of resonance signals and to assign any uncertainty on results. The influence of systematic errors is also considered.
Study of the partial decomposition of GaN layers grown by MOVPE with different coalescence degree
NASA Astrophysics Data System (ADS)
Bouazizi, H.; Chaaben, N.; El Gmili, Y.; Bchetnia, A.; Salvestrini, J. P.; El Jani, B.
2016-01-01
We investigated the partial decomposition of GaN layers grown with different coalescence degrees by atmospheric pressure metal organic vapor phase epitaxy (AP-MOVPE) on SiN treated sapphire substrate. The decomposition was performed in AP-MOVPE reactor under nitrogen (N2) flow at 1200 °C. The growth and decomposition processes were in-situ monitored by laser reflectometry (LR) at normal incidence. Surface morphology, crystalline and optical properties of GaN layers were examined before and after partial decomposition by scanning electron microscope (SEM) and high resolution X-ray diffraction (HRXRD). Low decomposition rate and low surface degradation were obtained for thick and most coalesced GaN layers. The partial decomposition did not significantly affect the optical and crystalline properties of GaN. In particular, HRXRD showed almost the same full width at halfmaximum (FWHM) of (00.2) and (10.2) rocking curves (RCs) before and after partial decomposition of coalesced GaN layer.
Kong Xiangkun; Liu Shaobin; Bian Borui; Li Haiming; Zhao Xin; Zhang Haifeng
2013-04-15
A 4 Multiplication-Sign 4 transfer matrix method has been applied to study the decomposition of any elliptically polarized wave in a magnetized resonator. When the incident elliptically polarized wave passes through the structure, it is orthogonally decomposed into two circular polarizations at two resonance frequencies. Without changing the structure of the resonator, the positions of the resonant frequencies of the right- and left-handed circularly polarized waves can be modulated by changing the external magnetized field. The results show that the proposed magnetized structure can be used to design a novel resonator, which can be applied in the decomposition of polarized electromagnetic waves.
SLAC three-body partial wave analysis system
Aston, D.; Lasinski, T.A.; Sinervo, P.K.
1985-10-01
We present a heuristic description of the SLAC-LBL three-meson partial wave model, and describe how we have implemented it at SLAC. The discussion details the assumptions of the model and the analysis, and emphasizes the methods we have used to prepare and fit the data. 28 refs., 12 figs., 1 tab.
Kullback relative entropy and characterization of partially polarized optical waves.
Réfrégier, Philippe; Goudail, François
2006-03-01
Different properties of partially polarized light are discussed using the Kullback relative entropy, which provides a physically meaningful measure of proximity between probability density functions (PDFs). For optical waves with a Gaussian PDF, the standard degree of polarization is a simple function of the Kullback relative entropy between the considered optical light and a totally depolarized light of the same intensity. It is shown that the Kullback relative entropies between different PDFs allow one to define other properties such as a degree of anisotropy and a degree of non-Gaussianity. It is also demonstrated that, in dimension three, the Kullback relative entropy between a partially polarized light and a totally depolarized light can lead to natural definitions of two degrees of polarization needed to characterize the polarization state. These analyses enlighten the physical meaning of partial polarization of light waves in terms of a measure of disorder provided by the Shannon entropy. PMID:16539066
Numerical method for wave forces acting on partially perforated caisson
NASA Astrophysics Data System (ADS)
Jiang, Feng; Tang, Xiao-cheng; Jin, Zhao; Zhang, Li; Chen, Hong-zhou
2015-04-01
The perforated caisson is widely applied to practical engineering because of its great advantages in effectively wave energy consumption and cost reduction. The attentions of many scientists were paid to the fluid-structure interaction between wave and perforated caisson studies, but until now, most concerns have been put on theoretical analysis and experimental model set up. In this paper, interaction between the wave and the partial perforated caisson in a 2D numerical wave flume is investigated by means of the renewed SPH algorithm, and the mathematical equations are in the form of SPH numerical approximation based on Navier-Stokes equations. The validity of the SPH mathematical method is examined and the simulated results are compared with the results of theoretical models, meanwhile the complex hydrodynamic characteristics when the water particles flow in or out of a wave absorbing chamber are analyzed and the wave pressure distribution of the perforated caisson is also addressed here. The relationship between the ratio of total horizontal force acting on caisson under regular waves and its influence factors is examined. The data show that the numerical calculation of the ratio of total horizontal force meets the empirical regression equation very well. The simulations of SPH about the wave nonlinearity and breaking are briefly depicted in the paper, suggesting that the advantages and great potentiality of the SPH method is significant compared with traditional methods.
Calculation of the Scattering Amplitude Without Partial Wave Expansion
NASA Technical Reports Server (NTRS)
Shertzer, J.; Temkin, Aaron; Fisher, Richard R. (Technical Monitor)
2001-01-01
Two developments in the direct calculation of the angular differential scattering amplitude have been implemented: (a) The integral expansion of the scattering amplitude is simplified by analytically integration over the azimuthal angle. (b) The resulting integral as a function of scattering angle is calculated by using the numerically generated wave function from a finite element method calculation. Results for electron-hydrogen scattering in the static approximation will be shown to be as accurate as a partial wave expansion with as many l's as is necessary for convergence at the incident energy being calculated.
Leistritz, Lutz; Witte, Herbert; Schiecke, Karin
2015-01-01
Quantification of functional connectivity in physiological networks is frequently performed by means of time-variant partial directed coherence (tvPDC), based on time-variant multivariate autoregressive models. The principle advantage of tvPDC lies in the combination of directionality, time variance and frequency selectivity simultaneously, offering a more differentiated view into complex brain networks. Yet the advantages specific to tvPDC also cause a large number of results, leading to serious problems in interpretability. To counter this issue, we propose the decomposition of multi-dimensional tvPDC results into a sum of rank-1 outer products. This leads to a data condensation which enables an advanced interpretation of results. Furthermore it is thereby possible to uncover inherent interaction patterns of induced neuronal subsystems by limiting the decomposition to several relevant channels, while retaining the global influence determined by the preceding multivariate AR estimation and tvPDC calculation of the entire scalp. Finally a comparison between several subjects is considerably easier, as individual tvPDC results are summarized within a comprehensive model equipped with subject-specific loading coefficients. A proof-of-principle of the approach is provided by means of simulated data; EEG data of an experiment concerning visual evoked potentials are used to demonstrate the applicability to real data. PMID:26046537
NASA Astrophysics Data System (ADS)
Wang, Z.; Quek, S. T.
2015-07-01
Performance of any structural health monitoring algorithm relies heavily on good measurement data. Hence, it is necessary to employ robust faulty sensor detection approaches to isolate sensors with abnormal behaviour and exclude the highly inaccurate data in the subsequent analysis. The independent component analysis (ICA) is implemented to detect the presence of sensors showing abnormal behaviour. A normalized form of the relative partial decomposition contribution (rPDC) is proposed to identify the faulty sensor. Both additive and multiplicative types of faults are addressed and the detectability illustrated using a numerical and an experimental example. An empirical method to establish control limits for detecting and identifying the type of fault is also proposed. The results show the effectiveness of the ICA and rPDC method in identifying faulty sensor assuming that baseline cases are available.
Middleton, Beth A.
2014-01-01
A cornerstone of ecosystem ecology, decomposition was recognized as a fundamental process driving the exchange of energy in ecosystems by early ecologists such as Lindeman 1942 and Odum 1960). In the history of ecology, studies of decomposition were incorporated into the International Biological Program in the 1960s to compare the nature of organic matter breakdown in various ecosystem types. Such studies still have an important role in ecological studies of today. More recent refinements have brought debates on the relative role microbes, invertebrates and environment in the breakdown and release of carbon into the atmosphere, as well as how nutrient cycling, production and other ecosystem processes regulated by decomposition may shift with climate change. Therefore, this bibliography examines the primary literature related to organic matter breakdown, but it also explores topics in which decomposition plays a key supporting role including vegetation composition, latitudinal gradients, altered ecosystems, anthropogenic impacts, carbon storage, and climate change models. Knowledge of these topics is relevant to both the study of ecosystem ecology as well projections of future conditions for human societies.
Gopalan, K.; Gopalsami, N.; Bakhtiari, S.; Raptis, A.C.
1995-07-01
This paper reports on wavelet-based decomposition methods and neural networks for remote monitoring of airborne chemicals using millimeter wave spectroscopy. Because of instrumentation noise and the presence of untargeted chemicals, direct decomposition of the spectra requires a large number of training data and yields low accuracy. A neural network trained with features obtained from a discrete wavelet transform is demonstrated to have better decomposition with faster training time. Results based on simulated and experimental spectra are presented to show the efficacy of the wavelet-based methods.
Wave Dispersion and Attenuation in Partially Saturated Sandstones
NASA Astrophysics Data System (ADS)
Nie, Jian-Xin; Yang, Ding-Hui; Yang, Hui-Zhu
2004-03-01
We investigate the wave dispersion and attenuation in partially water-saturated sandstones based on the improved Biot/squirt (BISQ) model in which the saturation is introduced. Numerical experiments indicate that the phase velocity of the fast P-wave decreases as the saturation increases in the low-frequency range (102-104 Hz), and reaches the minimum at the full-saturation state. The behaviour of the phase velocity varying with the saturation in the high-frequency range (104-106 Hz), however, is opposite to that in the low-frequency range. The peak value of P-wave attenuation increases with increasing saturation, and is the maximum at the fully saturated state. Numerical models and experiments show that the improved BISQ model is better than the traditional Gassmann-Biot model.
ERIC Educational Resources Information Center
Man, Yiu-Kwong; Leung, Allen
2012-01-01
In this paper, we introduce a new approach to compute the partial fraction decompositions of rational functions and describe the results of its trials at three secondary schools in Hong Kong. The data were collected via quizzes, questionnaire and interviews. In general, according to the responses from the teachers and students concerned, this new…
Seismoelectric wave propagation numerical modelling in partially saturated materials
NASA Astrophysics Data System (ADS)
Warden, S.; Garambois, S.; Jouniaux, L.; Brito, D.; Sailhac, P.; Bordes, C.
2013-09-01
To better understand and interpret seismoelectric measurements acquired over vadose environments, both the existing theory and the wave propagation modelling programmes, available for saturated materials, should be extended to partial saturation conditions. We propose here an extension of Pride's equations aiming to take into account partially saturated materials, in the case of a water-air mixture. This new set of equations was incorporated into an existing seismoelectric wave propagation modelling code, originally designed for stratified saturated media. This extension concerns both the mechanical part, using a generalization of the Biot-Gassmann theory, and the electromagnetic part, for which dielectric permittivity and electrical conductivity were expressed against water saturation. The dynamic seismoelectric coupling was written as a function of the streaming potential coefficient, which depends on saturation, using four different relations derived from recent laboratory or theoretical studies. In a second part, this extended programme was used to synthesize the seismoelectric response for a layered medium consisting of a partially saturated sand overburden on top of a saturated sandstone half-space. Subsequent analysis of the modelled amplitudes suggests that the typically very weak interface response (IR) may be best recovered when the shallow layer exhibits low saturation. We also use our programme to compute the seismoelectric response of a capillary fringe between a vadose sand overburden and a saturated sand half-space. Our first modelling results suggest that the study of the seismoelectric IR may help to detect a sharp saturation contrast better than a smooth saturation transition. In our example, a saturation contrast of 50 per cent between a fully saturated sand half-space and a partially saturated shallow sand layer yields a stronger IR than a stepwise decrease in saturation.
Direct Calculation of the Scattering Amplitude Without Partial Wave Analysis
NASA Technical Reports Server (NTRS)
Shertzer, J.; Temkin, A.; Fisher, Richard R. (Technical Monitor)
2001-01-01
Two new developments in scattering theory are reported. We show, in a practical way, how one can calculate the full scattering amplitude without invoking a partial wave expansion. First, the integral expression for the scattering amplitude f(theta) is simplified by an analytic integration over the azimuthal angle. Second, the full scattering wavefunction which appears in the integral expression for f(theta) is obtained by solving the Schrodinger equation with the finite element method (FEM). As an example, we calculate electron scattering from the Hartree potential. With minimal computational effort, we obtain accurate and stable results for the scattering amplitude.
Laboratory monitoring of P-waves in partially saturated sand
NASA Astrophysics Data System (ADS)
Barrière, J.; Bordes, C.; Brito, D.; Sénéchal, P.; Perroud, H.
2011-12-01
Seismic data depends on a variety of hydrogeological properties of the prospected porous media such as porosity, permeability and fluid saturation. We have performed a laboratory experiment in the kiloHertz range in order to analyze the role of partial saturation on direct propagating P-waves phase velocity and attenuation. The experiment consists of a sand-filled tank 107 cm x 34 cm x 35cm equipped with accelerometers and water capacitance probes. The P-waves seismic propagation is generated by hitting a steel ball on a granite plate on the one lateral side of the container. Several imbibition/drainage cycles are performed between the water residual saturation and the gas residual saturation. The laboratory seismic data are processed by two Continuous Wavelet Transforms using one real mother wavelet (Mexican hat) and one complex (Morlet) to recover velocity and attenuation as a function of frequency. Phase velocity of direct P-wave decreases with an increase of water content and is quite consistent with the low frequency limit of the Biot's theory both for imbibition and drainage. The interpretation of the P-waves attenuation needs to go beyond the macroscopic fluid flow of Biot's theory and to introduce a viscoelastic contribution linked to the grain to grain overall losses which are described by a constant Q-model. A strong hysteresis between imbibition and drainage is observed and explained by introducing an effective permeability depending on water and gas relative permeabilities (Van Genuchten model).
A correlated empirical mode decomposition method for partial discharge signal denoising
NASA Astrophysics Data System (ADS)
Tang, Ya-Wen; Tai, Cheng-Chi; Su, Ching-Chau; Chen, Chien-Yi; Chen, Jiann-Fuh
2010-08-01
Empirical mode decomposition (EMD) is a signal processing method used to extract intrinsic mode functions (IMFs) from a complicated signal. For a measurement with two or more correlated inputs, finding and capturing the correlated IMFs is a critical challenge that must be confronted. In this paper, a new correlated EMD method is proposed. The cross-correlation method was employed to determine dependence between the IMFs. To verify feasibility, an analysis was performed on simulated test signals and practically measured partial discharge (PD) signals collected from several acoustic emission sensors. At the surface of the gas-insulated transmission line, the PD signal arrived at the AE sensors with varying time delays and unique mechanism vibrations. Following an abnormal detection using the standard-deviation variation, the PD signal and the background signal of each sensor were applied using the correlated-EMD method. A twice correlated-EMD calculation was applied to the signals for the purpose of noise elimination. In addition, the unwanted low-frequency IMFs induced from the EMD calculations were excluded. The experimental results reveal that the correlated-EMD method performs well on both selecting and denoising the correlated IMFs. The results further provide analysis on correlated-input applications with a precise signal completely induced from the disturbance.
A New Pion-Nucleon Partial Wave Analysis
NASA Astrophysics Data System (ADS)
Sadler, Michael; Watson, Shon; Stahov, Jugoslav
2006-10-01
Existing determinations of the masses, widths and decay modes of low-lying excited states of the nucleon, as compiled in the Review of Particle Physics, are determined from energy-independent partial wave analyses of pion-nucleon scattering data. For the N*(1440) and most other resonances under 2 GeV, the analyses cited are the Karlsruhe-Helsinki, Carnegie Mellon-Berkeley and Kent State analyses, the latter of which used the elastic amplitudes from the other two. The data included in these analyses were published before 1980. Other analyses, notably the recent ones from George Washington University and the Pittsburgh-Argonne group, are ``not used for averages, fits, limits, etc.'' Complete sets of measurements (differential cross sections, analyzing powers and spin rotation parameters) have been measured in the N*(1440) resonance region since 1980, culminating in the Crystal Ball program at BNL to measure all-neutral final states (charge exchange, multiple pi-zero final states, and inverse photoproduction). A new partial wave analysis of the Karlsruhe-Helsinki type has been started by Abilene Christian University, University of Tuzla, and Rudjer Boskovic Institute. The analysis is constrained by fixed-t and interior hyperbolic dispersion relations. Comparisons of the new analysis to modern experimental data and to previous analyses will be presented.
Wave field decomposition of volcanic tremor at Pacaya Volcano, Guatemala
NASA Astrophysics Data System (ADS)
Lanza, F.; Waite, G. P.; Kenyon, L. M.
2013-12-01
A dense, small-aperture array of 12 short-period seismometers was deployed on the west flank of Pacaya volcano (Guatemala) and operated for 14 days in January 2011. The data were used to investigate the properties of the volcanic tremor wave field at the volcano. Volcanic tremor has been proven to be a powerful tool for eruption forecasting, therefore, identifying its source locations may shed new light on the dynamics of the volcano system. A preliminary spectral analysis highlights that most of the seismic energy is associated with six narrow spectral peaks between 1 and 6 Hz. After taking topography into account, we performed frequency-slowness analyses using the MUSIC algorithm and the semblance technique with the aim to define and locate the different components contributing to the wave field. Results show a complex wave field, with possibly multiple sources. We identify peaks at frequencies < 2 Hz as being related to anthropogenic sources coming from the N- NW direction where the geothermal plant and San Vincente Pacaya village are located. Azimuth measurements indicate that the 3 Hz signal propagates from the SE direction and it has been attributed to the new vent on the southeast flank of Pacaya Volcano. However, the presence of secondary peaks with azimuths of ˜ 200°, 150° and 70° seems to suggest either nonvolcanic sources or perhaps the presence of structural heterogeneities that produce strong scattered waves. At higher frequencies, results show effects of array aliasing, and therefore have not been considered in this study. The dispersive properties of the wave field have been investigated using the Spatial Auto-Correlation Method (SPAC). The dispersion characteristics of Rayleigh waves have been then inverted to find a shallow velocity model beneath the array, which shows a range of velocities from about 0.3 km/s to 2 km/s, in agreement with slowness values of the frequency bands considered. In detail, apparent velocities of 1-2 km/s dominate at
Scattering of acoustic evanescent waves by circular cylinders: Partial wave series solution
NASA Astrophysics Data System (ADS)
Marston, Philip L.
2002-05-01
Evanescent acoustical waves occur in a variety of situations such as when sound is incident on a fluid interface beyond the critical angle and when flexural waves on a plate are subsonic with respect to the surrounding fluid. The scattering by circular cylinders at normal incidence was calculated to give insight into the consequences on the scattering of the evanescence of the incident wave. To analyze the scattering, it is necessary to express the incident wave using a modified expansion involving cylindrical functions. For plane evanescent waves, the expansion becomes a double summation with products of modified and ordinary Bessel functions. The resulting modified series is found for the scattering by a fluid cylinder in an unbounded medium. The perfectly soft and rigid cases are also examined. Unlike the case of an ordinary incident wave, the counterpropagating partial waves of the same angular order have unequal magnitudes when the incident wave is evanescent. This is a consequence of the exponential dependence of the incident wave amplitude on the transverse coordinate. The associated exponential dependence of the scattering on the location of a scatterer was previously demonstrated [T. J. Matula and P. L. Marston, J. Acoust. Soc. Am. 93, 1192-1195 (1993)].
Spherical Harmonic Decomposition of Gravitational Waves Across Mesh Refinement Boundaries
NASA Technical Reports Server (NTRS)
Fiske, David R.; Baker, John; vanMeter, James R.; Centrella, Joan M.
2005-01-01
We evolve a linearized (Teukolsky) solution of the Einstein equations with a non-linear Einstein solver. Using this testbed, we are able to show that such gravitational waves, defined by the Weyl scalars in the Newman-Penrose formalism, propagate faithfully across mesh refinement boundaries, and use, for the first time to our knowledge, a novel algorithm due to Misner to compute spherical harmonic components of our waveforms. We show that the algorithm performs extremely well, even when the extraction sphere intersects refinement boundaries.
Search for Higher Flavor Multiplets in Partial Wave Analyses
Yakov Azimov; Richard Arndt; I.I. Strakovsky; Ron Workman; K. Goeke
2005-04-01
The possible existence of higher multi-quark flavor multiplets of baryons is investigated. We argue that the S-matrix should have poles with any quantum numbers, including those which are exotic. This argument provides a novel justification for the existence of hadrons with arbitrary exotic structure. Though it does not constitute a proof, there are still no theoretical arguments against exotics. We then consider KN and piN scattering. Conventional and modified partial-wave analyses provide several sets of candidates for correlated pairs (Theta1, Delta), each of which could label a related 27-plet. Properties of the pairs (masses, mass orderings, spin-parity quantum numbers) do not quite correspond to the current theoretical expectations. Decay widths of the candidates are either wider or narrower than expected. Possible reasons for such disagreements are briefly discussed.
Treatment of Ion-Atom Collisions Using a Partial-Wave Expansion of the Projectile Wavefunction
ERIC Educational Resources Information Center
Wong, T. G.; Foster, M.; Colgan, J.; Madison, D. H.
2009-01-01
We present calculations of ion-atom collisions using a partial-wave expansion of the projectile wavefunction. Most calculations of ion-atom collisions have typically used classical or plane-wave approximations for the projectile wavefunction, since partial-wave expansions are expected to require prohibitively large numbers of terms to converge…
NASA Technical Reports Server (NTRS)
Shen, Bo-Wen; Cheung, Samson; Li, Jui-Lin F.; Wu, Yu-ling
2013-01-01
In this study, we discuss the performance of the parallel ensemble empirical mode decomposition (EMD) in the analysis of tropical waves that are associated with tropical cyclone (TC) formation. To efficiently analyze high-resolution, global, multiple-dimensional data sets, we first implement multilevel parallelism into the ensemble EMD (EEMD) and obtain a parallel speedup of 720 using 200 eight-core processors. We then apply the parallel EEMD (PEEMD) to extract the intrinsic mode functions (IMFs) from preselected data sets that represent (1) idealized tropical waves and (2) large-scale environmental flows associated with Hurricane Sandy (2012). Results indicate that the PEEMD is efficient and effective in revealing the major wave characteristics of the data, such as wavelengths and periods, by sifting out the dominant (wave) components. This approach has a potential for hurricane climate study by examining the statistical relationship between tropical waves and TC formation.
Huang, Shaoguang; Tian, Lan; Ma, Xiaojie; Wei, Ying
2016-04-01
Hearing impaired people have their own hearing loss characteristics and listening preferences. Therefore hearing aid system should become more natural, humanized and personalized, which requires the filterbank in hearing aids provides flexible sound wave decomposition schemes, so that patients are likely to use the most suitable scheme for their own hearing compensation strategy. In this paper, a reconfigurable sound wave decomposition filterbank is proposed. The prototype filter is first cosine modulated to generate uniform subbands. Then by non-linear transformation the uniform subbands are mapped to nonuniform subbands. By changing the control parameters, the nonlinear transformation changes which leads to different subbands allocations. It provides four different sound wave decomposition schemes without changing the structure of the filterbank. The performance of the proposed reconfigurable filterbank was compared with that of fixed filerbanks, fully customizable filterbanks and other existing reconfigurable filterbanks. It is shown that the proposed filterbank provides satisfactory matching performance as well as low complexity and delay, which make it suitable for real hearing aid applications. PMID:26168447
Applicability of Parallel Computing to Partial Wave Analysis
NASA Astrophysics Data System (ADS)
Ruger, Justin; Gilfoyle, Gerard; Weygand, Dennis; CLAS Collaboration
2013-10-01
Bound states of Quantum Chromodynamics (QCD) give insights into the nature of confinement, a key element of the strong interaction. States may be identified from weak signals extracted from the analysis of high statistics data from reactions with many final state particles. One of the best tools for the analysis of these reactions is Partial Wave Analysis (PWA). PWA transforms an ensemble of experimental data from a large acceptance detector from free particle eigenstates to angular momentum eigenstates. The PWA program must be fast enough to deal with the large amounts of data available currently, as processing time scales with the number of events. The scope of this research is to study the applicability and scalability of Intel's Xeon Phi using the Many Integrated Core (MIC) architecture when applied to the existing PWA code at Jefferson Laboratory. An algorithm was developed for the Xeon Phi and scaled across 240 available threads, giving parallel functionality to the PWA which was originally written serially. This scaling can make the fitting process fifteen times faster. Supported by the US Department of Energy.
NASA Astrophysics Data System (ADS)
Man, Yiu-Kwong
2012-10-01
Partial fraction decomposition is a useful technique often taught at senior secondary or undergraduate levels to handle integrations, inverse Laplace transforms or linear ordinary differential equations, etc. In recent years, an improved Heaviside's approach to partial fraction decomposition was introduced and developed by the author. An important feature of this approach is that there is no need to solve a system of linear equations or to use differentiations to find the unknown coefficients of the partial fractions. In order to study its potential application in mathematics education at the undergraduate level, a pilot study of tryout at the Hong Kong Institute of Education has been conducted. The data are collected via quizzes, questionnaires and face-to-face interviews. In this article, the results and implications will be discussed. In general, according to the responses and feedbacks from the instructors and students concerned, the improved Heaviside approach is suitable to be introduced at the undergraduate level, as an alternative to the method of undetermined coefficients described in common undergraduate mathematics textbooks.
Fringe removal for continuous-wave terahertz imaging based on cartoon-texture decomposition
NASA Astrophysics Data System (ADS)
Qiao, Lingbo; Wang, Yingxin; Zhao, Ziran; Chen, Zhiqiang
2013-08-01
Continuous-wave (CW) terahertz (THz) imaging system has advantages of high power, compact structure and low cost, thus having been investigated for widespread applications. In typical reflection mode of CW imaging, the obtained image is usually degraded by repeated fringes, which is caused by interference phenomenon. The undesired interference signal originates from the reflection of surfaces of samples and lenses. When the samples are titled placed or their surfaces are uneven, the detected signal intensity is fluctuant even if the same sample lies in different positions. Therefore, small-sized or weekly absorbing objects are hard to be distinguished. Based on cartoon-texture decomposition, we propose a practical method to restore CW THz reflection images. After decomposition, the fringes and the objects are separated. In order to preserve edges, sharpening and fusion steps are employed respectively. The object in the final image is obvious with little loss of information.
Wave-Vortex Decomposition of One-Dimensional Ship Track Data
NASA Astrophysics Data System (ADS)
Callies, J.; Buhler, O.; Ferrari, R. M.
2014-12-01
Oceanic motions are dominated by geostrophic flows at the mesoscale (order 100 km) and by internal waves at small scales (order 100 m and smaller). It is anticipated that at some intermediate scale, there is a transition from geostrophically dominated flow to wave-dominated flow. Observing the flow at such intermediate scales, the submesoscales, is currently restricted to ship-based measurements. Information is often obtained in one spatial dimension only, with no temporal information available to distinguish between geostrophic flow and internal waves. We present a simple two-step method by which one-dimensional energy spectra can be decomposed into an internal-wave component and a geostrophic component if measurements of velocity along and across the ship track and buoyancy are available. In the first step a Helmholtz decomposition of the horizontal velocity spectra into rotational and divergent components is performed and in the second step an energy equipartition property of hydrostatic internal waves is exploited that allows diagnosing the wave energy spectrum solely from the observed horizontal velocities. The observed buoyancy spectrum can then be used to compute the residual geostrophic energy spectrum. We illustrate the method on two data sets from the eastern North Pacific and the Gulf Stream region. The method is also applicable to atmospheric data obtained by commercial aircraft.
NASA Astrophysics Data System (ADS)
Witos, F.; Gacek, Z.; Paduch, P.
2006-11-01
The problem touched in the article is decomposition of frequency characteristic of AE signals into elementary form of three-parametrical Gauss function. At the first stage, for modelled curves in form of sum of three-parametrical Gauss peaks, accordance of modelled curve and a curve resulting from a solutions obtained using method with dynamic windows, Levenberg-Marquardt algorithm, genetic algorithms and differential evolution algorithm are discussed. It is founded that analyses carried out by means differential evolution algorithm are effective and the computer system served an analysis of AE signal frequency characteristics was constructed. Decomposition of frequency characteristics for selected AE signals coming from modelled PD sources using different ends of the bushing, and real PD sources in generator coil bars are carried out.
Dimethyl methylphosphonate decomposition on fully oxidized and partially reduced ceria thin films
NASA Astrophysics Data System (ADS)
Chen, Donna A.; Ratliff, Jay S.; Hu, Xiaofeng; Gordon, Wesley O.; Senanayake, Sanjaya D.; Mullins, David R.
2010-03-01
The thermal decomposition of dimethyl methylphosphonate (DMMP) on crystalline ceria thin films grown on Ru(0 0 0 1) was studied by temperature programmed desorption (TPD), X-ray photoelectron spectroscopy (XPS) and infrared absorption reflection spectroscopy (IRAS). TPD experiments show that methanol and formaldehyde desorb as the two main products at 575 K, while water, formaldehyde and CO are produced above 800 K. IRAS studies demonstrate that DMMP adsorbs via the phosphoryl oxygen at 200 K, but the P dbnd O bond converts to a bridging O sbnd P sbnd O species at 300 K. DMMP decomposition initially occurs via P sbnd OCH 3 bond scission to form methyl methylphosphonate (MMP) and methyl phosphonate (MP) between 300 and 500 K; XPS and IRAS data are consistent with a methoxy intermediate on the surface at these temperatures. The more stable P sbnd CH 3 bonds remain intact up to 700 K, and the only surface intermediate at higher temperatures is believed to be PO x. Although the presence of PO x decreases activity for DMMP decomposition, some activity on the ceria surface remains even after 7 cycles of adsorption and reaction. The ceria films become reduced by multiple DMMP adsorption-reaction cycles, with the Ce +4 content dropping to 30% after seven cycles. Investigations of DMMP reaction on reduced ceria surfaces show that CO and H 2 are produced in addition to methanol and formaldehyde. Furthermore, DMMP decomposition activity on the reduced ceria films is almost completely inhibited after only 3 adsorption-reaction cycles. Similarities between DMMP and methanol chemistry on the ceria films suggest that methoxy is a key surface intermediate in both reactions.
Dimethyl methylphosphonate Decomposition on fully Oxidized and Partially Reduced ceria Thin Films
Chen, D.; Ratliff, J; Hu, X; Gordon, W; Senanayake, S; Mullins, D
2010-01-01
The thermal decomposition of dimethyl methylphosphonate (DMMP) on crystalline ceria thin films grown on Ru(0 0 0 1) was studied by temperature programmed desorption (TPD), X-ray photoelectron spectroscopy (XPS) and infrared absorption reflection spectroscopy (IRAS). TPD experiments show that methanol and formaldehyde desorb as the two main products at 575 K, while water, formaldehyde and CO are produced above 800 K. IRAS studies demonstrate that DMMP adsorbs via the phosphoryl oxygen at 200 K, but the P{double_bond}O bond converts to a bridging O{single_bond}P{single_bond}O species at 300 K. DMMP decomposition initially occurs via P{_}OCH{sub 3} bond scission to form methyl methylphosphonate (MMP) and methyl phosphonate (MP) between 300 and 500 K; XPS and IRAS data are consistent with a methoxy intermediate on the surface at these temperatures. The more stable P{_}CH{sub 3} bonds remain intact up to 700 K, and the only surface intermediate at higher temperatures is believed to be PO{sub x}. Although the presence of PO{sub x} decreases activity for DMMP decomposition, some activity on the ceria surface remains even after 7 cycles of adsorption and reaction. The ceria films become reduced by multiple DMMP adsorption-reaction cycles, with the Ce{sup +4} content dropping to 30% after seven cycles. Investigations of DMMP reaction on reduced ceria surfaces show that CO and H{sub 2} are produced in addition to methanol and formaldehyde. Furthermore, DMMP decomposition activity on the reduced ceria films is almost completely inhibited after only 3 adsorption-reaction cycles. Similarities between DMMP and methanol chemistry on the ceria films suggest that methoxy is a key surface intermediate in both reactions.
S. J. Reese; D. H. Hurley; H.W. Rollins
2006-04-01
The effect of surface acoustic waves, generated on a silver catalyst using a comb transducer, on the catalytic decomposition of ethanol is examined. The comb transducer employs purely mechanical means for surface acoustic wave (SAW) transduction. Unlike interdigital SAW transducers on piezoelectric substrates, the complicating effects of heat generation due to electromechanical coupling, high electric fields between adjacent electrodes, and acoustoelectric currents are avoided. The ethanol decomposition reactions are carried out at 473 K. The rates of acetaldehyde and ethylene production are retarded when acoustic waves are applied. The rates recover to varying degrees when acoustic excitation ceases.
Zheng, Rencheng; Nakano, Kimihiko; Ohashi, Rui; Okabe, Yoji; Shimazaki, Mamoru; Nakamura, Hiroki; Wu, Qi
2015-01-01
Ultrasonic wave-sensing technology has been applied for the health monitoring of composite structures, using normal fiber Bragg grating (FBG) sensors with a high-speed wavelength interrogation system of arrayed waveguide grating (AWG) filters; however, researchers are required to average thousands of repeated measurements to distinguish significant signals. To resolve this bottleneck problem, this study established a signal-processing strategy that improves the signal-to-noise ratio for the one-time measured signal of ultrasonic waves, by application of parallel factor analysis (PARAFAC) technology that produces unique multiway decomposition without additional orthogonal or independent constraints. Through bandpass processing of the AWG filter and complex wavelet transforms, ultrasonic wave signals are preprocessed as time, phase, and frequency profiles, and then decomposed into a series of conceptual three-way atoms by PARAFAC. While an ultrasonic wave results in a Bragg wavelength shift, antiphase fluctuations can be observed at two adjacent AWG ports. Thereby, concentrating on antiphase features among the three-way atoms, a fitting atom can be chosen and then restored to three-way profiles as a final result. An experimental study has revealed that the final result is consistent with the conventional 1024-data averaging signal, and relative error evaluation has indicated that the signal-to-noise ratio of ultrasonic waves can be significantly improved. PMID:26198232
Zheng, Rencheng; Nakano, Kimihiko; Ohashi, Rui; Okabe, Yoji; Shimazaki, Mamoru; Nakamura, Hiroki; Wu, Qi
2015-01-01
Ultrasonic wave-sensing technology has been applied for the health monitoring of composite structures, using normal fiber Bragg grating (FBG) sensors with a high-speed wavelength interrogation system of arrayed waveguide grating (AWG) filters; however, researchers are required to average thousands of repeated measurements to distinguish significant signals. To resolve this bottleneck problem, this study established a signal-processing strategy that improves the signal-to-noise ratio for the one-time measured signal of ultrasonic waves, by application of parallel factor analysis (PARAFAC) technology that produces unique multiway decomposition without additional orthogonal or independent constraints. Through bandpass processing of the AWG filter and complex wavelet transforms, ultrasonic wave signals are preprocessed as time, phase, and frequency profiles, and then decomposed into a series of conceptual three-way atoms by PARAFAC. While an ultrasonic wave results in a Bragg wavelength shift, antiphase fluctuations can be observed at two adjacent AWG ports. Thereby, concentrating on antiphase features among the three-way atoms, a fitting atom can be chosen and then restored to three-way profiles as a final result. An experimental study has revealed that the final result is consistent with the conventional 1024-data averaging signal, and relative error evaluation has indicated that the signal-to-noise ratio of ultrasonic waves can be significantly improved. PMID:26198232
Extracting planetary waves from geomagnetic time series using Empirical Mode Decomposition
NASA Astrophysics Data System (ADS)
Frühauff, Dennis; Glassmeier, Karl-Heinz; Lockwood, Michael; Heyner, Daniel
2015-07-01
Empirical Mode Decomposition is presented as an alternative to traditional analysis methods to decompose geomagnetic time series into spectral components. Important comments on the algorithm and its variations will be given. Using this technique, planetary wave modes of 5-, 10-, and 16-day mean periods can be extracted from magnetic field components of three different stations in Germany. In a second step, the amplitude modulation functions of these wave modes can be shown to contain significant contribution from solar cycle variation through correlation with smoothed sunspot numbers. Additionally, the data indicate connections with geomagnetic jerk occurrences, supported by a second set of data providing reconstructed near-Earth magnetic field for 150 years. Usually attributed to internal dynamo processes within the Earth's outer core, the question of who is impacting whom will be briefly discussed here.
NASA Astrophysics Data System (ADS)
Kurte, R.; Heise, H. M.; Klockow, D.
2001-05-01
Infrared spectroscopy is a powerful tool for the analysis of gaseous by-products in sulfur hexafluoride gas used as an insulator in high-voltage equipment. Sparks and electrical partial discharges were generated between different point-plane configurations within a custom-made discharge chamber constructed from stainless steel and Teflon ®. Various electrode materials were used such as stainless steel, copper, aluminium, silver, tungsten and tungsten/copper alloy. Owing to the different electrical conditions, a wide concentration range of the decomposition products existed. The main-products found were the sulfuroxyfluorides SOF 4 and SOF 2, as well as HF following experiments with partial discharges and sparking with energies around 1.0 J/spark. All infrared spectra were recorded using an FTIR-spectrometer equipped with a 10 cm gas cell. Quantification was carried out using classical least-squares and partial least-squares (PLS) with multivariate spectral data from selected intervals. PLS calibration models were also optimised under the constraint of a minimum number of spectral variables with a view to developing simple photometers based on a restricted number of laser wavelengths. Standard errors of prediction obtained by cross-validation of different PLS calibration models are reported for the compounds mentioned, as well as for SF 4, SO 2F 2 and SiF 4.
An application of wavelet transform for decomposition of millimeter-wave spectroscopic signals
Gopalan, K.; Gopalsami, N.; Bakhtiari, S.; Raptis, A.C.
1994-08-01
Millimeter-wave technique, based on rotational energy transitions of molecules, holds promise for remote monitoring of environmentally hazardous effluents from processes. Argonne National Laboratory is developing a millimeter-wave sensor based on active swept-frequency radar technique in the frequency range of 220-320 GHz. Because the line widths of millimeter-wave spectra of molecules at atmospheric pressure are broad ({approximately} 4 GHz half-width at half height), the composite spectrum of multicomponent mixtures of chemicals is generally complex and overlapping. This paper presents an application of discrete wavelet transform for efficient representation and decomposition of millimeter-wave spectral data. A two-layer back propagation neural network is trained using multifrequency wavelet coefficients of the signals as input features and the known composition of different chemicals in the mixture as target output vectors. After training, composition of an unknown mixture of the base chemicals is determined using the wavelet representation of its absorption spectra. Simulated and experimental spectral data were used to test the wavelet transform technique. Accurate values of individual chemical compositions resulted for noise-free laboratory data. In addition, the technique showed more robustness than conventional multivariate techniques under noisy conditions.
NASA Astrophysics Data System (ADS)
Frisch, H.
2010-11-01
Context. The linear polarization of a strong resonance lines observed near the solar limb is created by a multiple-scattering process. Partial frequency redistribution (PRD) effects must be accounted for to explain the polarization profiles. The redistribution matrix describing the scattering process is a sum of terms, each containing a PRD function multiplied by a Rayleigh type phase matrix. A standard approximation made in calculating the polarization is to average the PRD functions over all the scattering angles, because the numerical work needed to take the angle-dependence of the PRD functions into account is large and not always needed for reasonable evaluations of the polarization. Aims: This paper describes a Stokes parameters decomposition method, that is applicable in plane-parallel cylindrically symmetrical media, which aims at simplifying the numerical work needed to overcome the angle-average approximation. Methods: The decomposition method relies on an azimuthal Fourier expansion of the PRD functions associated to a decomposition of the phase matrices in terms of the Landi Degl'Innocenti irreducible spherical tensors for polarimetry T^K_Q(i, Ω) (i Stokes parameter index, Ω ray direction). The terms that depend on the azimuth of the scattering angle are retained in the phase matrices. Results: It is shown that the Stokes parameters I and Q, which have the same cylindrical symmetry as the medium, can be expressed in terms of four cylindrically symmetrical components I_Q^K (K = Q = 0, K = 2, Q = 0, 1, 2). The components with Q = 1, 2 are created by the angular dependence of the PRD functions. They go to zero at disk center, ensuring that Stokes Q also goes to zero. Each component I_Q^K is a solution to a standard radiative transfer equation. The source term S_Q^K are significantly simpler than the source terms corresponding to I and Q. They satisfy a set of integral equations that can be solved by an accelerated lambda iteration (ALI) method.
NASA Astrophysics Data System (ADS)
Olsson, Peter
2016-03-01
A new directional decomposition of the acoustic 3D wave equation is derived for spherically symmetric geometries, where the wave fields do not need to possess such a symmetry. This provides an alternative basis for various applications of techniques like invariant embedding and time domain Green functions in spherically symmetric geometries. Contrary to previous results on spherical wave splittings, the new decomposition is given in a very explicit form. The wave equation considered incorporates effects from radially varying compressibility and density, but also from anisotropic density, a property of certain so called metafluids. By applying the new spherical wave splitting, we show that all spherically symmetric acoustic metafluid cloaks are diffeomorphic images of a homogeneous and isotropic spherical ball of perfect fluid.
Heating of ions by low-frequency Alfven waves in partially ionized plasmas
Dong Chuanfei; Paty, Carol S.
2011-03-15
In the solar atmosphere, the chromospheric and coronal plasmas are much hotter than the visible photosphere. The heating of the solar atmosphere, including the partially ionized chromosphere and corona, remains largely unknown. In this letter, we demonstrate that the ions can be substantially heated by Alfven waves with very low frequencies in partially ionized low-beta plasmas. This differs from other Alfven wave related heating mechanisms such as ion-neutral collisional damping of Alfven waves and heating described by previous work on resonant Alfven wave heating. We find that the nonresonant Alfven wave heating is less efficient in partially ionized plasmas than when there are no ion-neutral collisions, and the heating efficiency depends on the ratio of the ion-neutral collision frequency to the ion gyrofrequency.
Partial reflections of radio waves from the lower ionosphere
NASA Technical Reports Server (NTRS)
Connolly, D. J.; Tanenbaum, S. B.
1972-01-01
The addition of phase difference measurements to partial reflection experiments is discussed, and some advantages of measuring electron density this way are pointed out. The additional information obtained reduces the requirement for an accurate predetermination of collision frequency. Calculations are also made to estimate the errors expected in partial-reflection experiments due to the assumption of Fresnel reflection and to the neglect of coupling between modes. In both cases, the errors are found to be of the same order as known errors in the measurements due to current instrumental limitations.
Study on the electromagnetic waves propagation characteristics in partially ionized plasma slabs
NASA Astrophysics Data System (ADS)
Wang, Zhi-Bin; Li, Bo-Wen; Nie, Qiu-Yue; Wang, Xiao-Gang; Kong, Fan-Rong
2016-05-01
Propagation characteristics of electromagnetic (EM) waves in partially ionized plasma slabs are studied in this paper. Such features are significant to applications in plasma antennas, blackout of re-entry flying vehicles, wave energy injection to plasmas, and etc. We in this paper developed a theoretical model of EM wave propagation perpendicular to a plasma slab with a one-dimensional density inhomogeneity along propagation direction to investigate essential characteristics of EM wave propagation in nonuniform plasmas. Particularly, the EM wave propagation in sub-wavelength plasma slabs, where the geometric optics approximation fails, is studied and in comparison with thicker slabs where the geometric optics approximation applies. The influences of both plasma and collisional frequencies, as well as the width of the plasma slab, on the EM wave propagation characteristics are discussed. The results can help the further understanding of propagation behaviours of EM waves in nonuniform plasma, and applications of the interactions between EM waves and plasmas.
Shock-wave structure in a partially ionized gas
NASA Technical Reports Server (NTRS)
Lu, C. S.; Huang, A. B.
1974-01-01
The structure of a steady plane shock in a partially ionized gas has been investigated using the Boltzmann equation with a kinetic model as the governing equation and the discrete ordinate method as a tool. The effects of the electric field induced by the charge separation on the shock structure have also been studied. Although the three species of an ionized gas travel with approximately the same macroscopic velocity, the individual distribution functions are found to be very different. In a strong shock the atom distribution function may have double peaks, while the ion distribution function has only one peak. Electrons are heated up much earlier than ions and atoms in a partially ionized gas. Because the interactions of electrons with atoms and with ions are different, the ion temperature can be different from the atom temperature.
Treatment of ion-atom collisions using a partial-wave expansion of the projectile wavefunction
Foster, M; Colgan, J; Wong, T G; Madison, D H
2008-01-01
We present calculations of ion-atom collisions using a partial-wave expansion of the projectile wavefunction. Most calculations of ion-atom collisions have typically used classical or plane-wave approximations for the projectile wavefunction, since partial-wave expansions are expected to require prohibitively large numbers of terms to converge scattering quantities. Here we show that such calculations are possible using modern high-performance computing. We demonstrate the utility of our method by examining elastic scattering of protons by hydrogen and helium atoms, problems familiar to undergraduate students of atomic scattering. Application to ionization of helium using partial-wave expansions of the projectile wavefunction, which has long been desirable in heavy-ion collision physics, is thus quite feasible.
NASA Astrophysics Data System (ADS)
Montaño Muñoz, Jennifer; Osorio Arias, Andres; Winter, Christian; Didenkulova, Ira; Otero, Luis
2015-04-01
Infragravity waves are long waves with periods between ~ 20 s and 300 s, these waves may dominate the hydrodynamics in the surf and swash zones, being the main driver of sediment transport and swash elevation (run-up). Data of pressure sensors at different cross-shore positions and camera systems that capture the swash excursion in a micro-tidal beach (Cartagena, Colombia, Caribbean Sea) and a macro-tidal beach (Norderney, Germany, North Sea) were analyzed to study the occurrence and temporal and spatial variability of infragravity waves. We used the Complete Ensemble Empirical Mode Decomposition (CEEMD) to decompose the time series into a finite set of "intrinsic mode functions" (IMFs). This method overcomes limitations of Fourier-based methods for time series analysis (e.g. FFT and wavelet techniques) that assume linear and stationary data. CEEMD was designed to analyze non-linear and non-stationary phenomena (as those in shallow waters), identifying processes with small amplitudes and low energy hidden in the data. A comparison with the Fourier spectrum shows the superiority of CEEMD to describe the behavior of ingragravity waves. Fourier spectra do not show infragravity energy in deeper waters; additionally, in shallow waters the energy of the spectra is spread in the infragravity band differing among sea states, therefore is not possible identifying a characteristic spectrum. On the other hand, with CEEMD the IMFs in the infragravity frequencies are observed in deeper waters, and the energy evolution cross-shore until the swash zone is shown at both beaches; furthermore, CEEMD shows the frequency clustering of the energy, allowing to see the gains or losses of energy at different frequencies. At the micro-tidal beach (Cartagena), infragravity energy is dominant in surf and swash zones for all analyzed sea states, with dominant energy in the IMF of about 100 s of period, showing infragravity wave selection. On the contrary, at the macro-tidal beach (Norderney
An algorithm for the calculation of the partial wave expansion of the Coulomb-distorted plane wave
NASA Astrophysics Data System (ADS)
Hornyak, I.; Kruppa, A. T.
2015-12-01
The partial wave expansion of the Coulomb-distorted plane wave is determined by the help of the complex generalized hypergeometric function 2F2(a , a ; a + l + 1 , a - l ; z) . An algorithm for the calculation of 2F2(a , a ; a + l + 1 , a - l ; z) is created and it is implemented as a FORTRAN-90 code. The code is fast and its accuracy is 14 significant decimal digits.
Evaluation of partial widths and branching ratios from resonance wave functions
Goldzak, Tamar; Gilary, Ido; Moiseyev, Nimrod
2010-11-15
A quantum system in a given resonance state has different open channels for decay. Partial widths are the decay rates of the resonance (metastable) state into the different open channels. Here we present a rigorous derivation of the partial widths from the solution of a time-dependent Schroedinger equation with outgoing boundary conditions. We show that the sum of the partial widths obtained from the resonance wave function is equal to the total width. The difference with respect to previous studies on partial widths and branching ratios is discussed.
NASA Astrophysics Data System (ADS)
Miroshnikov, Victor
2015-11-01
The Navier-Stokes system of PDEs is reduced to a system of the vorticity, continuity, Helmholtz, and Lamb-Helmholtz PDEs. The periodic Dirichlet problems are formulated for conservative internal waves vanishing at infinity in upper and lower domains. Stationary kinematic Fourier (SKF) structures, stationary kinematic Euler-Fourier (SKEF) structures, stationary dynamic Euler-Fourier (SDEF) structures, and SKEF-SDEF structures of three spatial variables and time are constructed to consider kinematic and dynamic problems of the three-dimensional theory of the Newtonian flows with harmonic velocity. Exact solutions for propagation and interaction of N internal waves in the upper and lower domains are developed by the method of decomposition in invariant structures and implemented through experimental and theoretical programming in Maple. Main results are summarized in a global existence theorem for the strong solutions. The SKEF, SDEF, and SKEF-SDEF structures of the cumulative flows are visualized by two-parametric surface plots for six fluid-dynamic variables.
Probing disturbances over canadian ionosphere using advance data analysis of wave decomposition
NASA Astrophysics Data System (ADS)
Kherani, Esfhan
2016-07-01
Using CHAIN network of GPS receivers, we present disturbances in total electron content (TEC) of the ionosphere on magnetically quiet day of 8 December 2009 and construct travel-time diagram to understand the propagation characteristics of these disturbances. We employ the wave decomposition method to identify the TEC disturbances. We found N-shaped amplified TEC disturbances at higher latitude around 80 N that appear during intensification of ionospheric current at ˜11 UT, suggesting them to be associated with energy input from magnetosphere. These TEC disturbances have spectral peak in between 55-65 minutes, originate in the vicnity of (80N,270W), propagate both southeastward and southwestward with similar velocity ˜80 m/s and arrives at latitude ˜55N around 20 UT. These propagation characteristcs classify them as medium-scale Traveling ionospheric disturbances (MSTIDs) and possibly of gravity wave origin. Noteworthy results of our study are following: (1) presence of dayside MSTIDs whose nightside counterpart is recently reported by Shiokawa et al (2012), (2) long-distance ˜2500 km propagation of dayside MSTIDs that is not reported for the nightside counterpart, (3) dayside MSIDs acquire largest amplitudes in 65-75 during 15-17 UT, similar to the nightside MSTIDs, (4) amplification of amplitudes of MSTIDs in the auroral oval latitudes and (5) identification of driving sources in two latitudes that enable them to propagate long distance.
NASA Astrophysics Data System (ADS)
Torregrosa, A. J.; Broatch, A.; Margot, X.; García-Tíscar, J.
2016-08-01
An experimental methodology is proposed to assess the noise emission of centrifugal turbocompressors like those of automotive turbochargers. A step-by-step procedure is detailed, starting from the theoretical considerations of sound measurement in flow ducts and examining specific experimental setup guidelines and signal processing routines. Special care is taken regarding some limiting factors that adversely affect the measuring of sound intensity in ducts, namely calibration, sensor placement and frequency ranges and restrictions. In order to provide illustrative examples of the proposed techniques and results, the methodology has been applied to the acoustic evaluation of a small automotive turbocharger in a flow bench. Samples of raw pressure spectra, decomposed pressure waves, calibration results, accurate surge characterization and final compressor noise maps and estimated spectrograms are provided. The analysis of selected frequency bands successfully shows how different, known noise phenomena of particular interest such as mid-frequency "whoosh noise" and low-frequency surge onset are correlated with operating conditions of the turbocharger. Comparison against external inlet orifice intensity measurements shows good correlation and improvement with respect to alternative wave decomposition techniques.
Analysis of non linear partially standing waves from 3D velocity measurements
NASA Astrophysics Data System (ADS)
Drevard, D.; Rey, V.; Svendsen, Ib; Fraunie, P.
2003-04-01
Surface gravity waves in the ocean exhibit an energy spectrum distributed in both frequency and direction of propagation. Wave data collection is of great importance in coastal zones for engineering and scientific studies. In particular, partially standing waves measurements near coastal structures and steep or barred beaches may be a requirement, for instance for morphodynamic studies. The aim of the present study is the analysis of partially standing surface waves icluding non-linear effects. According to 1st order Stokes theory, synchronous measurements of horizontal and vertical velocity components allow calculation of rate of standing waves (Drevard et al, 2003). In the present study, it is demonstrated that for deep water conditions, partially standing 2nd order Stokes waves induced velocity field is still represented by the 1st order solution for the velocity potential contrary to the surface elevation which exhibits harmonic components. For intermediate water depth, harmonic components appear not only in the surface elevation but also in the velocity fields, but their weight remains much smaller, because of the vertical decreasing wave induced motion. For irregular waves, the influence of the spectrum width on the non-linear effects in the analysis is discussed. Keywords: Wave measurements ; reflection ; non-linear effects Acknowledgements: This work was initiated during the stay of Prof. Ib Svendsen, as invited Professor, at LSEET in autumn 2002. This study is carried out in the framework of the Scientific French National Programmes PNEC ART7 and PATOM. Their financial supports are acknowledged References: Drevard, D., Meuret, A., Rey, V. Piazzola, J. And Dolle, A.. (2002). "Partially reflected waves measurements using Acoustic Doppler Velocimeter (ADV)", Submitted to ISOPE 03, Honolulu, Hawaii, May 2003.
Partial-wave analysis for elastic p{sup 13}C scattering at astrophysical energies
Dubovichenko, S. B.
2012-03-15
A standard partial-wave analysis was performed on the basis of known measurements of differential cross sections for elastic p{sup 13}C scattering at energies in the range 250-750 keV. This analysis revealed that, in the energy range being considered, it is sufficient to take into account the {sup 3}S{sub 1} wave alone. A potential for the triplet {sup 3}S{sub 1}-wave state of the p{sup 13}C system in the region of the J{sup p}T = 1{sup -1} resonance at 0.55 MeV was constructed on the basis of the phase shifts obtained from the aforementioned partial-wave analysis.
Dynamic mode decomposition identifies internal wave and vortical modes in stably stratified wakes
NASA Astrophysics Data System (ADS)
Xiang, Xinjiang; Chen, Kevin; Madison, Trystan; Spedding, Geoffrey
2015-11-01
Though detailed information has been assembled to describe the late wakes behind various objects in stably stratified fluids, less is known about the dynamics at early stages, when the flow first interacts with the ambient density gradient, beginning the transition to the late wake regime. Detailed velocity fields (and derivatives) were reported by Xiang et al. (J. Fluid Mech. 775, 149-177, 2015) for the near wake of a towed grid, with Re ∈ { 2700 , 11000 } and Fr ∈ { 0 . 6 , 9 . 1 } . Here using dynamic mode decomposition (DMD), the spatial and temporal evolution of the lee wave and shearing modes are extracted and examined for the same data set. Both dynamic modes show systematic dependence on Fr and Re, consistent with previous analysis. The results show the potential of DMD in analyzing the contribution of different modes in a complex, near wake evolution, including, but not limited to towed grids, and the wakes of more complicated towed geometries. Support from ONR N00014-11-1-0553 is most gratefully acknowledged.
NASA Astrophysics Data System (ADS)
Chaganti Subrahmanya Datta, Narendra
The flow structure of shockwave boundary layer interaction (SWBLI) has been studied using Rainbow Schlieren Deflectometry (RSD), Ensemble Averaging, Fast Fourier Transform (FFT), and snapshot Proper Orthogonal Decomposition (POD) techniques. The Mach number of the approach free-stream was Mach = 3. Shockwave was generated with a 12° wedge. The color schlieren pictures are used to determine the transverse ray deflections at each pixel of the pictures taken using a high speed camera. The interaction region structure is described statistically with the ensemble average and, root mean square deflections. FFT technique is used to determine the dominant frequencies at different regions of the flow field. Results indicate that low frequency oscillations dominate the flow field. The POD technique results complement the findings of the ensemble averaging technique and show that distinct regions contain most of the energy in the flow field. These distinct regions are located around the reflected shock, around the shock wave reaching into the approach boundary layer and around the separation region over the edge of the separation bubble.
Wave interaction with a partially reflecting vertical wall protected by a submerged porous bar
NASA Astrophysics Data System (ADS)
Zhao, Yang; Liu, Yong; Li, Huajun
2016-08-01
This study gives an analytical solution for wave interaction with a partially reflecting vertical wall protected by a submerged porous bar based on linear potential theory. The whole study domain is divided into multiple sub-regions in relation to the structures. The velocity potential in each sub-region is written as a series solution by the separation of variables. A partially reflecting boundary condition is used to describe the partial reflection of a vertical wall. Unknown expansion coefficients in the series solutions are determined by matching velocity potentials among different sub-regions. The analytical solution is verified by an independently developed multi-domain boundary element method (BEM) solution and experimental data. The wave run-up and wave force on the partially reflecting vertical wall are estimated and examined, which can be effectively reduced by the submerged porous bar. The horizontal space between the vertical wall and the submerged porous bar is a key factor, which affects the sheltering function of the porous bar. The wave resonance between the porous bar and the vertical wall may disappear when the vertical wall has a low reflection coefficient. The present analytical solution may be used to determine the optimum parameters of structures at a preliminary engineering design stage.
NASA Astrophysics Data System (ADS)
Humeida, Yousif; Pinfield, Valerie J.; Challis, Richard E.
2013-08-01
Ultrasonic arrays have seen increasing use for the characterisation of composite materials. In this paper, ultrasonic wave propagation in multilayer anisotropic materials has been modelled using plane wave and angular spectrum decomposition techniques. Different matrix techniques, such as the stiffness matrix method and the transfer matrix method, are used to calculate the reflection and transmission coefficients of ultrasonic plane waves in the considered media. Then, an angular decomposition technique is used to derive the bounded beams from finite-width ultrasonic array elements from the plane wave responses calculated earlier. This model is considered to be an analytical exact solution for the problem; hence the diffraction of waves in such composite materials can be calculated for different incident angles for a very wide range of frequencies. This model is validated against experimental measurements using the Full-Matrix Capture (FMC) of array data in both a homogeneous isotropic material, i.e. aluminium, and an inhomogeneous multilayer anisotropic material, i.e. a carbon fibre reinforced composite.
NASA Astrophysics Data System (ADS)
Chao, C. S.; Li, Y. D.; Liao, T. W.; Hung, T. C.; Luo, M. F.
2014-08-01
Various surface probe techniques were applied to investigate the decomposition of methanol on partially alumina-encapsulated Pt nanoclusters on an ordered thin film of Al2O3/NiAl(1 0 0). The alumina-encapsulated Pt clusters were prepared on annealing Pt clusters (grown by vapor deposition onto the Al2O3/NiAl(1 0 0) at 300 K) to 650 K under UHV conditions. The annealed cluster became a Pt1+-Pt2+ state and partially encapsulated with inert alumina. Methanol on the partially encapsulated Pt clusters decomposed only on the uncovered Pt sites, and through both dehydrogenation to CO and scission of the C-O bond. In comparison to the reactions on Pt clusters, the C-O bond scission was altered little on the partially encapsulated clusters whereas the dehydrogenation was hindered to a certain extent. The quantities of CO and hydrogen produced from the dehydrogenation per surface Pt on the partially encapsulated clusters amounted to only half those on Pt clusters. The altered methanol decomposition was correlated to both electronic and ensemble effects.
A poroelastic model for ultrasonic wave attenuation in partially frozen brines
NASA Astrophysics Data System (ADS)
Matsushima, Jun; Nibe, Takao; Suzuki, Makoto; Kato, Yoshibumi; Rokugawa, Shuichi
2011-02-01
Although there are many possible mechanisms for the intrinsic seismic attenuation in composite materials that include fluids, relative motion between solids and fluids during seismic wave propagation is one of the most important attenuation mechanisms. In our previous study, we conducted ultrasonic wave transmission measurements on an ice-brine coexisting system to examine the influence on ultrasonic waves of the unfrozen brine in the pore microstructure of ice. In order to elucidate the physical mechanism responsible for ultrasonic wave attenuation in the frequency range of 350-600kHz, measured at different temperatures in partially frozen brines, we employed a poroelastic model based on the Biot theory to describe the propagation of ultrasonic waves through partially frozen brines. By assuming that the solid phase is ice and the liquid phase is the unfrozen brine, fluid properties measured by a pulsed nuclear magnetic resonance technique were used to calculate porosities at different temperatures. The computed intrinsic attenuation at 500kHz cannot completely predict the measured attenuation results from the experimental study in an ice-brine coexisting system, which suggests that other attenuation mechanisms such as the squirt-flow mechanism and wave scattering effect should be taken into account.
Simultaneous observations of gravity waves in auroras and partial reflection radar data
NASA Astrophysics Data System (ADS)
Roldugin, Valentin; Cherniakov, Sergey; Roldugin, Aleksey
2016-07-01
Some events of wave-like patterns of night sky intensity were revealed from the obtained data of the all-sky camera at the observatory "Lovozero" (67.97 N, 35.02 E). Their wave-lengths were about several tens kilometers and their time periods were about 15-30 minutes. We consider the wave-like structures as manifestation of acoustic-gravity waves. Two cases (28 January 2012 and 26 February 2012) were compared with the data of the partial reflection radar at the observatory "Tumanny" (69.0 N, 35.7 E). At these cases peaks of reflection intensity took place at 80-90 km, and the intensity on these altitudes oscillated with periods which were similar to the luminous ones.
Mixing of partial waves near B*B̄^{*} threshold in e⁺e⁻ annihilation
Li, Xin; Voloshin, M. B.
2013-05-31
We consider the production of B*B̄^{*} meson pairs in e⁺e⁻ annihilation near the threshold. The rescattering due to pion exchange between the mesons results in a mixing between three partial wave amplitudes: two P-wave amplitudes with the total spin of the meson pair S=0 and S=2 and an F-wave amplitude. The mixing due to pion exchange with a low momentum transfer is calculable up to c.m. energy E≈15–20 MeV above the threshold. We find that the P–F mixing is numerically quite small in this energy range, while the mixing of the two P-wave amplitudes is rapidly changing with energy and can reach of order one at such low energies.
Mixing of partial waves near B*B̄* threshold in e⁺e⁻ annihilation
Li, Xin; Voloshin, M. B.
2013-05-31
We consider the production of B*B̄* meson pairs in e⁺e⁻ annihilation near the threshold. The rescattering due to pion exchange between the mesons results in a mixing between three partial wave amplitudes: two P-wave amplitudes with the total spin of the meson pair S=0 and S=2 and an F-wave amplitude. The mixing due to pion exchange with a low momentum transfer is calculable up to c.m. energy E≈15–20 MeV above the threshold. We find that the P–F mixing is numerically quite small in this energy range, while the mixing of the two P-wave amplitudes is rapidly changing with energy andmore » can reach of order one at such low energies.« less
Raman rogue waves in a partially mode-locked fiber laser.
Runge, Antoine F J; Aguergaray, Claude; Broderick, Neil G R; Erkintalo, Miro
2014-01-15
We report on an experimental study of spectral fluctuations induced by intracavity Raman conversion in a passively partially mode-locked, all-normal dispersion fiber laser. Specifically, we use dispersive Fourier transformation to measure single-shot spectra of Raman-induced noise-like pulses, demonstrating that for low cavity gain values Raman emission is sporadic and follows rogue-wave-like probability distributions, while a saturated regime with Gaussian statistics is obtained for high pump powers. Our experiments further reveal intracavity rogue waves originating from cascaded Raman dynamics. PMID:24562136
Partial Reflection and Trapping of a Fast-mode Wave in Solar Coronal Arcade Loops
NASA Astrophysics Data System (ADS)
Kumar, Pankaj; Innes, D. E.
2015-04-01
We report on the first direct observation of a fast-mode wave propagating along and perpendicular to cool (171 Å) arcade loops observed by the Solar Dynamics Observatory/Atmospheric Imaging Assembly (AIA). The wave was associated with an impulsive/compact flare near the edge of a sunspot. The EUV wavefront expanded radially outward from the flare center and decelerated in the corona from 1060 to 760 km s-1 within ˜3-4 minutes. Part of the EUV wave propagated along a large-scale arcade of cool loops and was partially reflected back to the flare site. The phase speed of the wave was about 1450 km s-1, which is interpreted as a fast-mode wave. A second overlying loop arcade, orientated perpendicular to the cool arcade, is heated and becomes visible in the AIA hot channels. These hot loops sway in time with the EUV wave, as it propagated to and fro along the lower loop arcade. We suggest that an impulsive energy release at one of the footpoints of the arcade loops causes the onset of an EUV shock wave that propagates along and perpendicular to the magnetic field.
Trapped internal waves over undular topography in a partially mixed estuary
NASA Astrophysics Data System (ADS)
Pietrzak, J.; Labeur, R. J.
The flow of a stratified fluid over small-scale topographic features in an estuary may generate significant internal wave activity. Lee waves and upstream influence generated at isolated topographic features have received considerable attention during the past few decades. Field surveys of a partially mixed estuary, the Rotterdam Waterway, in 1987, also showed a plethora of internal wave activity generated by isolated topography, banks and groynes. Additionally it revealed a spectacular series of resonant internal waves trapped above low-amplitude bed waves. The internal waves reached amplitudes of 3-4 m in an estuary with a mean depth of 16 m. The waves were observed during the decreasing flood tide and are thought to make a significant contribution to turbulence production and mixing. However, while stationary linear and finite amplitude theories can be used to explain the presence of these waves, it is important to further investigate their time-dependent and non-linear behaviour. With the development of advanced non-hydrostatic models it now becomes possible to further investigate these waves through numerical experimentation. This is the focus of the work presented here. The non-hydrostatic finite element numerical model FINEL3D developed by Labeur was used in the experiments presented here. The model has been shown to work well in a number of stratified flow investigations. Here, we first show that the model reproduces the field data and for idealised stationary flow scenarios that the results are in agreement with the resonant response predicted by linear theory. Then we explore the effects of non-linearity and time dependence and consider the importance of resonant internal waves for turbulence production in stratified coastal environments.
NASA Astrophysics Data System (ADS)
Futatani, Shimpei; Bos, Wouter J. T.; del-Castillo-Negrete, Diego; Schneider, Kai; Benkadda, Sadruddin; Farge, Marie
2011-03-01
We assess two techniques for extracting coherent vortices out of turbulent flows: the wavelet based Coherent Vorticity Extraction (CVE) and the Proper Orthogonal Decomposition (POD). The former decomposes the flow field into an orthogonal wavelet representation and subsequent thresholding of the coefficients allows one to split the flow into organized coherent vortices with non-Gaussian statistics and an incoherent random part which is structureless. POD is based on the singular value decomposition and decomposes the flow into basis functions which are optimal with respect to the retained energy for the ensemble average. Both techniques are applied to direct numerical simulation data of two-dimensional drift-wave turbulence governed by Hasegawa-Wakatani equation, considering two limit cases: the quasi-hydrodynamic and the quasi-adiabatic regimes. The results are compared in terms of compression rate, retained energy, retained enstrophy and retained radial flux, together with the enstrophy spectrum and higher order statistics.
A Rosetta Stone Relating Conventions In Photo-Meson Partial Wave Analyses
A.M. Sandorfi, B. Dey, A. Sarantsev, L. Tiator, R. Workman
2012-04-01
A new generation of complete experiments in pseudoscalar meson photo-production is being pursued at several laboratories. While new data are emerging, there is some confusion regarding definitions of asymmetries and the conventions used in partial wave analyses (PWA). We present expressions for constructing asymmetries as coordinate-system independent ratios of cross sections, along with the names used for these ratios by different PWA groups.
O (p6) extension of the large-NC partial wave dispersion relations
NASA Astrophysics Data System (ADS)
Guo, Z. H.; Sanz-Cillero, J. J.; Zheng, H. Q.
2008-04-01
Continuing our previous work [Z.H. Guo, J.J. Sanz-Cillero, H.Q. Zheng, JHEP 0706 (2007) 030], large-NC techniques and partial wave dispersion relations are used to discuss ππ scattering amplitudes. We get a set of predictions for O (p6) low-energy chiral perturbation theory couplings. They are provided in terms of the masses and decay widths of scalar and vector mesons.
NASA Technical Reports Server (NTRS)
Hayes, E. F.; Kouri, D. J.
1971-01-01
Coupled integral equations are derived for the full scattering amplitudes for both reactive and nonreactive channels. The equations do not involve any partial wave expansion and are obtained using channel operators for reactive and nonreactive collisions. These coupled integral equations are similar in nature to equations derived for purely nonreactive collisions of structureless particles. Using numerical quadrature techniques, these equations may be reduced to simultaneous algebraic equations which may then be solved.
Ovenstone,J.; White, J.; Misture, S.
2008-01-01
High-temperature X-ray diffraction has been used to investigate the phase stability of lanthanum strontium cobalt oxide (LSC) for a range of materials with the formula La1-xSrxCoO3-{delta} (x = 0.7, 0.4, and 0.2). The stability of LSC increases with La content in low oxygen partial pressures at high temperature. Oxygen vacancy ordering has been observed for all three compositions in either low oxygen pressure or under reducing gas, as evidenced by the formation of the brownmillerite phase. The crystal structure of the vacancy-ordered phase was determined using Rietveld analysis of synchrotron X-ray diffraction data. The decomposition products under low oxygen pressure and in reducing conditions have been identified and characterized, including the phase transition and thermal expansion of the primary decomposition products, LaSrCoO4 and LaSrCoO3.5.
Plateau Waves of Intracranial Pressure and Partial Pressure of Cerebral Oxygen.
Lang, Erhard W; Kasprowicz, Magdalena; Smielewski, Peter; Pickard, John; Czosnyka, Marek
2016-01-01
This study investigates 55 intracranial pressure (ICP) plateau waves recorded in 20 patients after severe traumatic brain injury (TBI) with a focus on a moving correlation coefficient between mean arterial pressure (ABP) and ICP, called PRx, which serves as a marker of cerebrovascular reactivity, and a moving correlation coefficient between ABP and cerebral partial pressure of oxygen (pbtO2), called ORx, which serves as a marker for cerebral oxygen reactivity. ICP and ICPamplitude increased significantly during the plateau waves, whereas CPP and pbtO2 decreased significantly. ABP, ABP amplitude, and heart rate remained unchanged. In 73 % of plateau waves PRx increased during the wave. ORx showed an increase during and a decrease after the plateau waves, which was not statistically significant. Our data show profound cerebral vasoparalysis on top of the wave and, to a lesser extent, impairment of cerebral oxygen reactivity. The different behavior of the indices may be due to the different latencies of the cerebral blood flow and oxygen level control mechanisms. While cerebrovascular reactivity is a rapidly reacting mechanism, cerebral oxygen reactivity is slower. PMID:27165902
Using a partial-wave method for sound-mean-flow scattering problems.
Berthet, R; Coste, C
2003-03-01
We present a semianalytical method, based on a partial-wave expansion and valid in the short wavelength limit for small Mach number flows, to analyze sound-vortical-flow interactions. It is more powerful than ray-tracing methods because it gives both amplitude and phase of the sound wave, and because it is less restrictive on the smallness of the wavelength. In contrast with the Born approximation approach, this method allows the computation of the sound field in the whole interaction domain (including the near field), and preserves energy conservation. Vortical flows with finite circulation are amenable to our analysis, which gives a satisfactory description of wave front dislocation by vorticity, in good agreement with direct numerical simulations. We extend previous versions of this method to the case of smooth vorticity profiles which are observed in aeroacoustics experiments. PMID:12689176
Heating of the Partially Ionized Solar Chromosphere by Waves in Magnetic Structures
NASA Astrophysics Data System (ADS)
Shelyag, S.; Khomenko, E.; de Vicente, A.; Przybylski, D.
2016-03-01
In this paper, we show a “proof of concept” of the heating mechanism of the solar chromosphere due to wave dissipation caused by the effects of partial ionization. Numerical modeling of non-linear wave propagation in a magnetic flux tube, embedded in the solar atmosphere, is performed by solving a system of single-fluid quasi-MHD equations, which take into account the ambipolar term from the generalized Ohm’s law. It is shown that perturbations caused by magnetic waves can be effectively dissipated due to ambipolar diffusion. The energy input by this mechanism is continuous and shown to be more efficient than dissipation of static currents, ultimately leading to chromospheric temperature increase in magnetic structures.
Cobos, C J; Sölter, L; Tellbach, E; Troe, J
2014-06-01
The thermal decomposition reactions of CF3CF2H and CF3CFHCF3 have been studied in shock waves by monitoring the appearance of CF2 radicals. Temperatures in the range 1400-2000 K and Ar bath gas concentrations in the range (2-10) × 10(-5) mol cm(-3) were employed. It is shown that the reactions are initiated by C-C bond fission and not by HF elimination. Differing conclusions in the literature about the primary decomposition products, such as deduced from experiments at very low pressures, are attributed to unimolecular falloff effects. By increasing the initial reactant concentrations in Ar from 60 to 1000 ppm, a retardation of CF2 formation was observed while the final CF2 yields remained close to two CF2 per C2F5H or three CF2 per C3F7H decomposed. This is explained by secondary bimolecular reactions which lead to comparably stable transient species like CF3H, releasing CF2 at a slower rate. Quantum-chemical calculations and kinetic modeling help to identify the reaction pathways and provide estimates of rate constants for a series of primary and secondary reactions in the decomposition mechanism. PMID:24352693
Highly directive Fabry-Perot leaky-wave nanoantennas based on optical partially reflective surfaces
Lorente-Crespo, M.; Mateo-Segura, C.
2015-05-04
Nanoantennas enhance the conversion between highly localized electromagnetic fields and far-field radiation. Here, we investigate the response of a nano-patch partially reflective surface backed with a silver mirror to an optical source embedded at the centre of the structure. Using full wave simulations, we demonstrate a two orders of magnitude increased directivity compared to the isotropic radiator, 50% power confinement to a 13.8° width beam and a ±16 nm bandwidth. Our antenna does not rely on plasmonic phenomena thus reducing non-radiative losses and conserving source coherence.
Partial-wave analysis of all nucleon-nucleon scattering data below 350 MeV
Stoks, V.G.J.; Klomp, R.A.M.; Rentmeester, M.C.M.; de Swart, J.J. )
1993-08-01
We present a multienergy partial-wave analysis of all [ital NN] scattering data below [ital T][sub lab]=350 MeV, published in a regular physics journal between 1955 and 1992. After careful examination, our final database consists of 1787 [ital pp] and 2514 [ital np] scattering data. Our fit to these data results in [chi][sup 2]/[ital N][sub df]=1.08, with [ital N][sub df]=3945 the total number of degrees of freedom. All phase shifts and mixing parameters can be determined accurately.
SAID Partial Wave Analyses from CNS DAC (Center for Nuclear Studies Data Analysis Center)
George Washington University (GW) has one of the largest university-based nuclear-physics groups in the nation. Many of the current and future projects are geared to Thomas Jefferson National Accelerator Facility (JLab) at Newport News, VA. JLab is the world's premier electron accelerator for nuclear physics, and GW is one of the charter members of the governing body of JLab, the Southeastern Universities Research Association (SURA). The George Washington Data Analysis Center (DAC) was created in 1998 by an agreement among the Department of Energy, Jefferson Lab, and the GW Center for Nuclear Studies.The activities of the DAC fall into four distinct categories: 1) Performing partial-wave analyses of fundamental two- and three-body reactions; 2) Maintenance of databases associated with these reactions; 3) Development of software to disseminate DAC results (as well as the results of competing model-independent analyses and potential approaches); and 4) Phenomenological and theoretical investigations which bridge the gap between theory and experiment; in particular, the extraction of N* and D * hadronic and electromagnetic couplings. Partial Wave Analyses (and the associated databases) available at GW are: Pion-Nucleon, Kaon-Nucleon, Nucleon-Nucleon, Pion Photoproduction, Pion Electroproduction, Kaon Photoproduction, Eta Photoproduction, Eta-Prime Photoproduction, Pion-Deuteron (elastic), and Pion-Deuteron to Proton+Proton. [Taken from http://www.gwu.edu/~ndl/dac.htm">http://www.gwu.edu/~ndl/dac.htm
NASA Astrophysics Data System (ADS)
Li, Jia; Wu, Pinghui; Chang, Liping
2016-02-01
Within the first-order Born approximation, the spectrum of light generated by the scattering of a partially coherent wave from a quasi-homogeneous (QH) medium is derived. In particular, the partially coherent incident wave is produced by Young's pinholes. It is shown that the spectrum of the scattered field is identical to the spectrum of incident plane waves if the Fourier transform of the normalized correlation coefficient (NCC) of the scattering potential satisfies a certain scaling law. The scaling law is valid when the medium size is sufficiently small compared with the space between Young' pinholes. Furthermore, comparisons are made between our conditions with the previous results.
Two-atom energy spectrum in a harmonic trap near a Feshbach resonance at higher partial waves
NASA Astrophysics Data System (ADS)
Suzuki, Akira; Liang, Yi; Bhaduri, Rajat K.
2009-09-01
Two atoms in an optical lattice may be made to interact strongly at higher partial waves near a Feshbach resonance. These atoms, under appropriate constraints, could be bosonic or fermionic. The universal l=2 energy spectrum for such a system, with a caveat, is presented in this paper and checked with the spectrum obtained by direct numerical integration of the Schrödinger equation. The results reported here extend those of Yip for p -wave resonance [S.-K. Yip, Phys. Rev. A 78, 013612 (2008)], while exploring the limitations of a universal expression for the spectrum for the higher partial waves.
Gaussian beam decomposition of high frequency wave fields using expectation-maximization
Ariel, Gil; Engquist, Bjoern; Tanushev, Nicolay M.; Tsai, Richard
2011-03-20
A new numerical method for approximating highly oscillatory wave fields as a superposition of Gaussian beams is presented. The method estimates the number of beams and their parameters automatically. This is achieved by an expectation-maximization algorithm that fits real, positive Gaussians to the energy of the highly oscillatory wave fields and its Fourier transform. Beam parameters are further refined by an optimization procedure that minimizes the difference between the Gaussian beam superposition and the highly oscillatory wave field in the energy norm.
Höhne, Christian; Prager, Jens; Gravenkamp, Hauke
2015-12-01
In this paper, a method to determine the complex dispersion relations of axially symmetric guided waves in cylindrical structures is presented as an alternative to the currently established numerical procedures. The method is based on a spectral decomposition into eigenfunctions of the Laplace operator on the cross-section of the waveguide. This translates the calculation of real or complex wave numbers at a given frequency into solving an eigenvalue problem. Cylindrical rods and plates are treated as the asymptotic cases of cylindrical structures and used to generalize the method to the case of hollow cylinders. The presented method is superior to direct root-finding algorithms in the sense that no initial guess values are needed to determine the complex wave numbers and that neither starting at low frequencies nor subsequent mode tracking is required. The results obtained with this method are shown to be reasonably close to those calculated by other means and an estimate for the achievable accuracy is given. PMID:26126952
Feng, Xiaobing
1996-12-31
A non-overlapping domain decomposition iterative method is proposed and analyzed for mixed finite element methods for a sequence of noncoercive elliptic systems with radiation boundary conditions. These differential systems describe the motion of a nearly elastic solid in the frequency domain. The convergence of the iterative procedure is demonstrated and the rate of convergence is derived for the case when the domain is decomposed into subdomains in which each subdomain consists of an individual element associated with the mixed finite elements. The hybridization of mixed finite element methods plays a important role in the construction of the discrete procedure.
Futatani, S.; Bos, W.J.T.; Del-Castillo-Negrete, Diego B; Schneider, Kai; Benkadda, S.; Farge, Marie
2011-01-01
We assess two techniques for extracting coherent vortices out of turbulent flows: the wavelet based Coherent Vorticity Extraction (CVE) and the Proper Orthogonal Decomposition (POD). The former decomposes the flow field into an orthogonal wavelet representation and subsequent thresholding of the coefficients allows one to split the flow into organized coherent vortices with non-Gaussian statistics and an incoherent random part which is structureless. POD is based on the singular value decomposition and decomposes the flow into basis functions which are optimal with respect to the retained energy for the ensemble average. Both techniques are applied to direct numerical simulation data of two-dimensional drift-wave turbulence governed by Hasegawa Wakatani equation, considering two limit cases: the quasi-hydrodynamic and the quasi-adiabatic regimes. The results are compared in terms of compression rate, retained energy, retained enstrophy and retained radial flux, together with the enstrophy spectrum and higher order statistics. (c) 2010 Published by Elsevier Masson SAS on behalf of Academie des sciences.
NASA Astrophysics Data System (ADS)
Zhu, Shangguo; Tan, Shina
2014-03-01
It is well-known that cold atoms near s-wave Feshbach resonances have universal properties that are insensitive to the short-range details of the interaction. What is less known is that atoms near higher partial wave Feshbach resonances also have remarkable universal properties. We will illustrate this with a single atom interacting resonantly with two fixed static centers. At a Feshbach resonance point with orbital angular momentum L >= 1 , we find 2 L + 1 shallow bound states whose energies behave like 1 /R 2 L + 1 when the distance R between the two centers is large. This sheds additional light on the fundamental question whether Efimov effect exists for higher partial wave resonances. The effects of nonresonant partial-wave channels and the shape parameters in the effective range expansions enter as correction terms. Near p-wave and higher partial wave resonances, the energies can be described by a simple universal formula in terms of a parameter called ``proximity parameter.'' We will also discuss modifications of the low energy physics due to the long range Van der Waals potential. We gratefully acknowledge support by the National Science Foundation under Grant No. PHY-1068511 and by the Alfred P. Sloan Foundation.
Two-fluid modeling of magnetosonic wave propagation in the partially ionized solar chromosphere
NASA Astrophysics Data System (ADS)
Maneva, Yana; Alvarez Laguna, Alejandro; Lani, Andrea; Poedts, Stefaan
2016-04-01
We perform 2D two-fluid simulations to study the effects of ion-neutral interactions on the propagation of magnetosonic waves in the partially ionized solar chromosphere, where the number density of neutrals significantly exceeds the number density of protons at low heights. Thus modeling the neutral-ion interactions and studying the effect of neutrals on the ambient plasma properties becomes important for better understanding the observed emission lines and the propagation of disturbances from the photosphere to the transition region and the corona. The role of charged particles (electrons and ions) is combined within resistive MHD approach with Coulomb collisions and anisotropic heat flux determined by Braginskii's transport coefficients. The electromagnetic fields are evolved according to the full Maxwell equations, allowing for propagation of higher frequency waves neglected by the standard MHD approximation. Separate mass, momentum and energy conservation equations are considered for the neutrals and the interaction between the different fluids is determined by the chemical reactions, such as impact ionization, radiative recombination and charge exchange, provided as additional source terms. To initialize the system we consider an ideal gas equation of state with equal initial temperatures for the electrons, ions and the neutrals and different density profiles. The initial temperature and density profiles are height-dependent and follow VAL C atmospheric model for the solar chromosphere. We have searched for a chemical and collisional equilibrium between the ions and the neutrals to minimize any unphysical outflows and artificial heating induced by initial pressure imbalances. Including different magnetic field profiles brings new source of plasma heating through Ohmic dissipation. The excitation and propagation of the magnetosonic waves depends on the type of the external velocity driver. As the waves propagate through the gravitationally stratified media
Zhang, Xiaoxing; Li, Xin; Luo, Chenchen; Dong, Xingchen; Zhou, Lei
2015-01-01
Sulfur hexafluoride (SF6) is widely utilized in gas-insulated switchgear (GIS). However, part of SF6 decomposes into different components under partial discharge (PD) conditions. Previous research has shown that the gas responses of intrinsic and 4 Å-type molecular sieve-deposited multi-wall carbon nanotubes (MWNTs) to SOF2 and SO2F2, two important decomposition components of SF6, are not obvious. In this study, a K-type molecular sieve-deposited MWNTs sensor was developed. Its gas response characteristics and the influence of the mixture ratios of gases on the gas-sensing properties were studied. The results showed that, for sensors with gas mixture ratios of 5:1, 10:1, and 20:1, the resistance change rate increased by nearly 13.0% after SOF2 adsorption, almost 10 times that of MWNTs sensors, while the sensors’ resistance change rate with a mixture ratio of 10:1 reached 17.3% after SO2F2 adsorption, nearly nine times that of intrinsic MWNT sensors. Besides, a good linear relationship was observed between concentration of decomposition components and the resistance change rate of sensors. PMID:26569245
Zhang, Xiaoxing; Li, Xin; Luo, Chenchen; Dong, Xingchen; Zhou, Lei
2015-01-01
Sulfur hexafluoride (SF6) is widely utilized in gas-insulated switchgear (GIS). However, part of SF6 decomposes into different components under partial discharge (PD) conditions. Previous research has shown that the gas responses of intrinsic and 4 Å-type molecular sieve-deposited multi-wall carbon nanotubes (MWNTs) to SOF2 and SO2F2, two important decomposition components of SF6, are not obvious. In this study, a K-type molecular sieve-deposited MWNTs sensor was developed. Its gas response characteristics and the influence of the mixture ratios of gases on the gas-sensing properties were studied. The results showed that, for sensors with gas mixture ratios of 5:1, 10:1, and 20:1, the resistance change rate increased by nearly 13.0% after SOF2 adsorption, almost 10 times that of MWNTs sensors, while the sensors' resistance change rate with a mixture ratio of 10:1 reached 17.3% after SO2F2 adsorption, nearly nine times that of intrinsic MWNT sensors. Besides, a good linear relationship was observed between concentration of decomposition components and the resistance change rate of sensors. PMID:26569245
Trigonometric Integrals via Partial Fractions
ERIC Educational Resources Information Center
Chen, H.; Fulford, M.
2005-01-01
Parametric differentiation is used to derive the partial fractions decompositions of certain rational functions. Those decompositions enable us to integrate some new combinations of trigonometric functions.
TE and TM beam decomposition of time-harmonic electromagnetic waves.
Melamed, Timor
2011-03-01
The present contribution is concerned with applying beam-type expansion to planar aperture time-harmonic electromagnetic field distribution in which the propagating elements, the electromagnetic beam-type wave objects, are decomposed into transverse electric (TE) and transverse magnetic (TM) field constituents. This procedure is essential for applying Maxwell's boundary conditions for solving different scattering problems. The propagating field is described as a discrete superposition of tilted and shifted TE and TM electromagnetic beams over the frame-based spatial-directional expansion lattice. These vector wave objects are evaluated either by applying differential operators to scalar beam propagators, or by using plane-wave spectral representations. Explicit asymptotic expressions for scalar, as well as for electromagnetic, Gaussian beam propagators are presented as well. PMID:21383822
PyPWA: A partial-wave/amplitude analysis software framework
NASA Astrophysics Data System (ADS)
Salgado, Carlos
2016-05-01
The PyPWA project aims to develop a software framework for Partial Wave and Amplitude Analysis of data; providing the user with software tools to identify resonances from multi-particle final states in photoproduction. Most of the code is written in Python. The software is divided into two main branches: one general-shell where amplitude's parameters (or any parametric model) are to be estimated from the data. This branch also includes software to produce simulated data-sets using the fitted amplitudes. A second branch contains a specific realization of the isobar model (with room to include Deck-type and other isobar model extensions) to perform PWA with an interface into the computer resources at Jefferson Lab. We are currently implementing parallelism and vectorization using the Intel's Xeon Phi family of coprocessors.
Partial wave analysis of the reaction gamma p -> p omega$ and the search for nucleon resonances
M. Williams, D. Applegate, M. Bellis, C.A. Meyer
2009-12-01
An event-based partial wave analysis (PWA) of the reaction gamma p -> p omega has been performed on a high-statistics dataset obtained using the CLAS at Jefferson Lab for center-of-mass energies from threshold up to 2.4 GeV. This analysis benefits from access to the world's first high precision spin density matrix element measurements, available to the event-based PWA through the decay distribution of omega-> pi+ pi - pi0. The data confirm the dominance of the t-channel pi0 exchange amplitude in the forward direction. The dominant resonance contributions are consistent with the previously identified states F[15](1680) and D[13](1700) near threshold, as well as the G[17](2190) at higher energies. Suggestive evidence for the presence of a J(P)=5/2(+) state around 2 GeV, a "missing" state, has also been found. Evidence for other states is inconclusive.
Chao, T.T.; Sanzolone, R.F.
1992-01-01
Sample decomposition is a fundamental and integral step in the procedure of geochemical analysis. It is often the limiting factor to sample throughput, especially with the recent application of the fast and modern multi-element measurement instrumentation. The complexity of geological materials makes it necessary to choose the sample decomposition technique that is compatible with the specific objective of the analysis. When selecting a decomposition technique, consideration should be given to the chemical and mineralogical characteristics of the sample, elements to be determined, precision and accuracy requirements, sample throughput, technical capability of personnel, and time constraints. This paper addresses these concerns and discusses the attributes and limitations of many techniques of sample decomposition along with examples of their application to geochemical analysis. The chemical properties of reagents as to their function as decomposition agents are also reviewed. The section on acid dissolution techniques addresses the various inorganic acids that are used individually or in combination in both open and closed systems. Fluxes used in sample fusion are discussed. The promising microwave-oven technology and the emerging field of automation are also examined. A section on applications highlights the use of decomposition techniques for the determination of Au, platinum group elements (PGEs), Hg, U, hydride-forming elements, rare earth elements (REEs), and multi-elements in geological materials. Partial dissolution techniques used for geochemical exploration which have been treated in detail elsewhere are not discussed here; nor are fire-assaying for noble metals and decomposition techniques for X-ray fluorescence or nuclear methods be discussed. ?? 1992.
Fast solution of elliptic partial differential equations using linear combinations of plane waves.
Pérez-Jordá, José M
2016-02-01
Given an arbitrary elliptic partial differential equation (PDE), a procedure for obtaining its solution is proposed based on the method of Ritz: the solution is written as a linear combination of plane waves and the coefficients are obtained by variational minimization. The PDE to be solved is cast as a system of linear equations Ax=b, where the matrix A is not sparse, which prevents the straightforward application of standard iterative methods in order to solve it. This sparseness problem can be circumvented by means of a recursive bisection approach based on the fast Fourier transform, which makes it possible to implement fast versions of some stationary iterative methods (such as Gauss-Seidel) consuming O(NlogN) memory and executing an iteration in O(Nlog(2)N) time, N being the number of plane waves used. In a similar way, fast versions of Krylov subspace methods and multigrid methods can also be implemented. These procedures are tested on Poisson's equation expressed in adaptive coordinates. It is found that the best results are obtained with the GMRES method using a multigrid preconditioner with Gauss-Seidel relaxation steps. PMID:26986436
X-ray standing wave analysis of nanostructures using partially coherent radiation
Tiwari, M. K. Das, Gangadhar; Bedzyk, M. J.
2015-09-07
The effect of longitudinal (or temporal) coherence on total reflection assisted x-ray standing wave (TR-XSW) analysis of nanoscale materials is quantitatively demonstrated by showing how the XSW fringe visibility can be strongly damped by decreasing the spectral resolution of the incident x-ray beam. The correction for nonzero wavelength dispersion (δλ ≠ 0) of the incident x-ray wave field is accounted for in the model computations of TR-XSW assisted angle dependent fluorescence yields of the nanostructure coatings on x-ray mirror surfaces. Given examples include 90 nm diameter Au nanospheres deposited on a Si(100) surface and a 3 nm thick Zn layer trapped on top a 100 nm Langmuir-Blodgett film coating on a Au mirror surface. Present method opens up important applications, such as enabling XSW studies of large dimensioned nanostructures using conventional laboratory based partially coherent x-ray sources.
Fast solution of elliptic partial differential equations using linear combinations of plane waves
NASA Astrophysics Data System (ADS)
Pérez-Jordá, José M.
2016-02-01
Given an arbitrary elliptic partial differential equation (PDE), a procedure for obtaining its solution is proposed based on the method of Ritz: the solution is written as a linear combination of plane waves and the coefficients are obtained by variational minimization. The PDE to be solved is cast as a system of linear equations A x =b , where the matrix A is not sparse, which prevents the straightforward application of standard iterative methods in order to solve it. This sparseness problem can be circumvented by means of a recursive bisection approach based on the fast Fourier transform, which makes it possible to implement fast versions of some stationary iterative methods (such as Gauss-Seidel) consuming O (N logN ) memory and executing an iteration in O (N log2N ) time, N being the number of plane waves used. In a similar way, fast versions of Krylov subspace methods and multigrid methods can also be implemented. These procedures are tested on Poisson's equation expressed in adaptive coordinates. It is found that the best results are obtained with the GMRES method using a multigrid preconditioner with Gauss-Seidel relaxation steps.
Are seismic wave velocities and anisotropies reliable proxies for partial melts?
NASA Astrophysics Data System (ADS)
Lee, Amicia; Torvela, Taija; Lloyd, Geoffrey; Walker, Andrew
2015-04-01
Partial melts and their segregation weaken mineral crystallographic alignment, resulting in a decrease in seismic anisotropy (AV). Furthermore, introduction of melt induces a drop in seismic wave velocities, especially for shear (Vs) but also compressional (Vp) waves, although some solid-state processes can also lead to velocity drops. Thus, decreases in AV and/or V are often used to infer the presence and even the amount of melt in both the crust and mantle, for example via the Vp/Vs ratio. However, evidence is accumulating that the relationship between melt fraction and seismic properties is not straight-forward. We consider how varying melt fraction (f) might affect crustal seismic properties. Our modelling approach is based on electron backscattered diffraction (EBSD) analysis of crystallographic preferred orientation (CPO) patterns from granulite facies sheared migmatites. The CPO data are used to model the seismic properties of rocks with different solid/melt proportions. Subsequently, melt was simulated via an isotropic elastic stiffness matrix and combined mathematically with the CPO-derived seismic properties, and seismic properties then recalculated to take into account the presence of melt. These melt models, therefore, predict changes in seismic properties at different f. The models show that low (c. f < 0.15) and high (0.7 < f < 1) values affect seismic properties much more than the 'crystal mush' part (0.1 < f < 0.7): velocities (V) and anisotropies (AV) for both low and high f drop rapidly but 'plateau' at intermediate f. Our results imply that V and, especially, AV may not be reliable proxies for the amount of crustal melt present. Seismic wave behaviour in crystal-supported (0.1 < f < 0.7) material may be controlled by the solid rather than the melt phase.
Blankleider, B.; Afnan, I.R.
1985-04-01
The polarization observables of the reactions parrow parrow ..-->.. ..pi../sup +/d, parrowp ..-->.. darrow..pi../sup +/, and ..pi..darrow ..-->.. ..pi..darrow are investigated. Expressions relating these observables directly to (LSJ) partial wave amplitudes are derived and tabulations of the partial wave contributions are given for some of the observables. Examples are given of how such tabulations can be useful for optimizing the connection between theory and experiment and in suggesting possible new experiments. All observables are also calculated numerically using a unitary few-body model of the NN-..pi..NN system to generate the amplitudes. Sensitivity to the choice of P/sub 11/ interaction is investigated.
NASA Astrophysics Data System (ADS)
Gundlach, Carsten; Martín-García, José M.; Garfinkle, David
2013-07-01
We investigate numerical methods for wave equations in n + 2 spacetime dimensions, written in spherical coordinates, decomposed in spherical harmonics on Sn, and finite-differenced in the remaining coordinates r and t. Such an approach is useful when the full physical problem has spherical symmetry, for perturbation theory about a spherical background, or in the presence of boundaries with spherical topology. The key numerical difficulty arises from lower order 1/r terms at the origin r = 0. As a toy model for this, we consider the flat space linear wave equation in the form \\dot{\\pi }=\\psi ^{\\prime }+p\\psi /r, \\dot{\\psi }=\\pi ^{\\prime }, where p = 2l + n and l is the leading spherical harmonic index. We propose a class of summation by parts (SBP) finite-differencing methods that conserve a discrete energy up to boundary terms, thus guaranteeing stability and convergence in the energy norm. We explicitly construct SBP schemes that are second- and fourth-order accurate at interior points and the symmetry boundary r = 0, and first- and second-order accurate at the outer boundary r = R.
Partial Antisymmetry and Approximate Primitive Wave Functions for Interacting Electronic Groups.
NASA Astrophysics Data System (ADS)
Vergenz, Robert Allan
The partial antisymmetry (PA) theorem of W. H. Adams (Chem. Phys. Letters, 68, 511 (1979)) shows that if one can determine an N-electron eigenfunction of a certain non-linear operator, then one can use the eigenfunction, without using full antisymmetry (FA), to calculate an eigenvalue of the Schrodinger Hamiltonian for the system. The operator neither depends on nor commutes with the antisymmetrizer, but involves partial antisymmetrizers. This work provides an initial numerical test of a new approach to calculating approximate interatomic interaction energies based on the PA theorem. Interaction energies were calculated for X ^1Sigma^{+}_ {rm g} Ne_2, Li_2 and Na_2, X^1Sigma^{+} LiNa, X^2Sigma^{+} _{rm g} Li_2 ^{+}, x ^7Sigma ^{+}_{rm u} N_2, x ^3Sigma ^{+}_{rm u} Li_2 and Na_2, x ^3Sigma^{+} LiNa and ionic and covalent configurations of X ^1Sigma^{+} LiF, all at several internuclear distances. Spin-coupled products of single determinants approximated the atomic wave functions, and accurate HF atomic bases were used. Three methods were used: the conventional method based on FA, the PA approach, and a method based on a hybrid set of assumptions. Results were compared with accurate potential curves from the literature. In nine cases of the eleven, including both bonding and repulsive interactions, the PA approximation gave results that were better or roughly the same as those using FA. In these cases there is thus no penalty exacted for the use of PA, though it is shown to be easier to use.
Fully and partially coherent pathways in multiply enhanced odd-order wave-mixing spectroscopy.
Mathew, Nathan A; Yurs, Lena A; Block, Stephen B; Pakoulev, Andrei V; Kornau, Kathryn M; Sibert, Edwin L; Wright, John C
2010-01-21
Nuclear magnetic resonance spectroscopy relies on using multiple excitation pulses to create multiple quantum coherences that provide great specificity for chemical measurements. Coherent multidimensional spectroscopy (CMDS) is the optical analogue of NMR. Current CMDS methods use three excitation pulses and phase matching to create zero, single, and double quantum coherences. In order to create higher order multiple quantum coherences, the number of interactions must be increased by raising the excitation intensities high enough to create Rabi frequencies that are comparable to the dephasing rates of vibrational coherences. The higher Rabi frequencies create multiple, odd-order coherence pathways. The coherence pathways that involve intermediate populations are partially coherent and are sensitive to population relaxation effects. Pathways that are fully coherent involve only coherences and measure the direct coupling between excited quantum states. The fully coherent pathways are related to the multiple quantum coherences created in multiple pulse NMR methods such as heteronuclear multiple quantum coherence (HMQC) spectroscopy with the important difference that HMQC NMR methods have a defined number of interactions and avoid dynamic Stark effects whereas the multiply enhanced odd-order wave-mixing pathways do not. The difference arises because CMDS methods use phase matching to define the interactions and at high intensities, multiple pathways obey the same phase matching conditions. The multiple pathways correspond to the pathways created by dynamic Stark effects. This paper uses rhodium dicarbonyl chelate (RDC) as a model to demonstrate the characteristics of multiply enhanced odd-order wave-mixing (MEOW) methods. Dynamic Stark effects excite vibrational ladders on the symmetric and asymmetric CO stretch modes and create a series of multiple quantum coherences and populations using partially and fully coherent pathways. Vibrational quantum states up to v = 6
Mughab, S.F.
1985-01-01
A long standing discrepancy between measurements and calculations of the sign of the incoherent scattering length is attributed to two sources: (1) spin dependence of the potential scattering radius and (2) identification of additional s-wave resonances at higher neutron energies. Detailed examination of the reaction /sup 27/Al (n vector,..gamma..) /sup 28/Al induced by thermal neutrons revealed that R/sub +/ - R/sub -/ = 0.32 +- 0.10 fm. Also shape fit analysis of the total cross section showed the presence of s-wave resonances at neutron energies 280, 386, 422, 491, 523, and 615 keV. One interesting outcome is the demonstration of the admixture of s- and d-wave partial waves in these resonances and the presence of a large d-wave neutron strength in the above energy region.
NASA Astrophysics Data System (ADS)
Jackson, I.; Faul, U. H.; Fitz Gerald, J. D.
2001-12-01
The frequency-dependent mechanical behaviour expected of Earth materials at high temperature places a special premium on laboratory measurements of wave speeds and attenuation at seismic frequencies. The symposium in honour of Mervyn Paterson provides a welcome opportunity to acknowledge his vital role in the design of the specialised equipment for this purpose described by Jackson and Paterson (PEPI 45: 349-367, 1987; Pageoph 141: 445-466, 1993). This instrument allows the study of low-strain high-temperature viscoelastic behaviour through the application of torsional forced oscillation/ microcreep techniques within the P-T environment (200 MPa, 1600 K) provided by an internally heated gas apparatus. Application of these techniques to fine-grained synthetic olivine polycrystals is beginning to provide a robust basis for the understanding of seismic wave attenuation (and dispersion) in the upper mantle under sub-solidus conditions. More recently, we have begun to explore the effects of partial melting through the fabrication, characterisation and mechanical testing of a suite of fine-grained olivine polycrystals containing up to 4% basaltic melt. The most striking effect of the added melt is the appearance of a melt-related dissipation peak superimposed upon the dissipation background characteristic of melt-free materials - which varies monotonically with period and temperature. The melt-related dissipation peak is adequately modelled as a Gaussian in log X, where X = To exp(E/RT). The melt-related dissipation peak sweeps across the seismic band from period To > 100 s to To < 1 s as temperature increases across the range 1300 - 1600 K producing pronounced systematic changes in the frequency dependence of 1/Q, that may be seismologically observable. >http://rses.anu.adu.au/petrophysics/PetroHome.html
Wei, Ying; Liu, Debao
2013-06-01
Current hearing-aid systems have fixed sound wave decomposition plans due to the use of fixed filterbanks, thus cannot provide enough flexibility for the compensation of different hearing impairment cases. In this paper, a reconfigurable filterbank that consists of a multiband-generation block and a subband-selection block is proposed. Different subbands can be produced according to the control parameters without changing the structure of the filterbank system. The use of interpolation, decimation, and frequency-response masking enables us to reduce the computational complexity by realizing the entire system with only three prototype filters. Reconfigurability of the proposed filterbank enables hearing-impaired people to customize hearing aids based on their own specific conditions to improve their hearing ability. We show, by means of examples, that the proposed filterbank can achieve a better matching to the audiogram and has smaller complexity compared with the fixed filterbank. The drawback of the proposed method is that the throughput delay is relatively long (>20 ms), which needs to be further reduced before it can be used in a real hearing-aid application. PMID:23335662
Real-time Automatic Detectors of P and S Waves Using Singular Values Decomposition
NASA Astrophysics Data System (ADS)
Kurzon, I.; Vernon, F.; Rosenberger, A.; Ben-Zion, Y.
2013-12-01
We implement a new method for the automatic detection of the primary P and S phases using Singular Value Decomposition (SVD) analysis. The method is based on a real-time iteration algorithm of Rosenberger (2010) for the SVD of three component seismograms. Rosenberger's algorithm identifies the incidence angle by applying SVD and separates the waveforms into their P and S components. We have been using the same algorithm with the modification that we filter the waveforms prior to the SVD, and then apply SNR (Signal-to-Noise Ratio) detectors for picking the P and S arrivals, on the new filtered+SVD-separated channels. A recent deployment in San Jacinto Fault Zone area provides a very dense seismic network that allows us to test the detection algorithm in diverse setting, such as: events with different source mechanisms, stations with different site characteristics, and ray paths that diverge from the SVD approximation used in the algorithm, (e.g., rays propagating within the fault and recorded on linear arrays, crossing the fault). We have found that a Butterworth band-pass filter of 2-30Hz, with four poles at each of the corner frequencies, shows the best performance in a large variety of events and stations within the SJFZ. Using the SVD detectors we obtain a similar number of P and S picks, which is a rare thing to see in ordinary SNR detectors. Also for the actual real-time operation of the ANZA and SJFZ real-time seismic networks, the above filter (2-30Hz) shows a very impressive performance, tested on many events and several aftershock sequences in the region from the MW 5.2 of June 2005, through the MW 5.4 of July 2010, to MW 4.7 of March 2013. Here we show the results of testing the detectors on the most complex and intense aftershock sequence, the MW 5.2 of June 2005, in which in the very first hour there were ~4 events a minute. This aftershock sequence was thoroughly reviewed by several analysts, identifying 294 events in the first hour, located in a
Partial wave analysis of the Dirac fermions scattered from Schwarzschild black holes
NASA Astrophysics Data System (ADS)
Cotăescu, Ion I.; Crucean, Cosmin; Sporea, Ciprian A.
2016-03-01
Asymptotic analytic solutions of the Dirac equation, giving the scattering modes (of the continuous energy spectrum, E>mc^2) in Schwarzschild's chart and Cartesian gauge, are used for building the partial wave analysis of Dirac fermions scattered by black holes. In this framework, the analytic expressions of the differential cross section and induced polarization degree are derived in terms of scattering angle, mass of the black hole, and energy and mass of the fermion. Moreover, the closed form of the absorption cross section due to the scattering modes is derived showing that in the high-energy limit this tends to the event horizon area regardless of the fermion mass (including zero). A graphical study presents the differential cross section analyzing the forward/backward scattering (known also as glory scattering) and the polarization degree as functions of scattering angle. The graphical analysis shows the presence of oscillations in scattering intensity around forward/backward directions, phenomena known as spiral scattering. The energy dependence of the differential cross section is also established by using analytical and graphical methods.
Bian, Xihui; Li, Shujuan; Lin, Ligang; Tan, Xiaoyao; Fan, Qingjie; Li, Ming
2016-06-21
Accurate prediction of the model is fundamental to the successful analysis of complex samples. To utilize abundant information embedded over frequency and time domains, a novel regression model is presented for quantitative analysis of hydrocarbon contents in the fuel oil samples. The proposed method named as high and low frequency unfolded PLSR (HLUPLSR), which integrates empirical mode decomposition (EMD) and unfolded strategy with partial least squares regression (PLSR). In the proposed method, the original signals are firstly decomposed into a finite number of intrinsic mode functions (IMFs) and a residue by EMD. Secondly, the former high frequency IMFs are summed as a high frequency matrix and the latter IMFs and residue are summed as a low frequency matrix. Finally, the two matrices are unfolded to an extended matrix in variable dimension, and then the PLSR model is built between the extended matrix and the target values. Coupled with Ultraviolet (UV) spectroscopy, HLUPLSR has been applied to determine hydrocarbon contents of light gas oil and diesel fuels samples. Comparing with single PLSR and other signal processing techniques, the proposed method shows superiority in prediction ability and better model interpretation. Therefore, HLUPLSR method provides a promising tool for quantitative analysis of complex samples. PMID:27188313
Domain decomposition for aerodynamic and aeroacoustic analyses, and optimization
NASA Technical Reports Server (NTRS)
Baysal, Oktay
1995-01-01
The overarching theme was the domain decomposition, which intended to improve the numerical solution technique for the partial differential equations at hand; in the present study, those that governed either the fluid flow, or the aeroacoustic wave propagation, or the sensitivity analysis for a gradient-based optimization. The role of the domain decomposition extended beyond the original impetus of discretizing geometrical complex regions or writing modular software for distributed-hardware computers. It induced function-space decompositions and operator decompositions that offered the valuable property of near independence of operator evaluation tasks. The objectives have gravitated about the extensions and implementations of either the previously developed or concurrently being developed methodologies: (1) aerodynamic sensitivity analysis with domain decomposition (SADD); (2) computational aeroacoustics of cavities; and (3) dynamic, multibody computational fluid dynamics using unstructured meshes.
Hadzimehmedovic, M.; Osmanovic, H.; Stahov, J.; Ceci, S.; Svarc, A.
2011-09-15
Each and every energy-dependent partial-wave analysis is parametrizing the pole positions in a procedure defined by the way the continuous energy dependence is implemented. These pole positions are, henceforth, inherently model dependent. To reduce this model dependence, we use only one, coupled-channel, unitary, fully analytic method based on the isobar approximation to extract the pole positions from each available member of the worldwide collection of partial-wave amplitudes, which are understood as nothing more but a good energy-dependent representation of genuine experimental numbers assembled in a form of partial-wave data. In that way, the model dependence related to the different assumptions on the analytic form of the partial-wave amplitudes is avoided, and the true confidence limit for the existence of a particular resonant state, at least in one model, is established. The way the method works and first results are demonstrated for the S{sub 11} partial wave.
NASA Astrophysics Data System (ADS)
Zhu, Shangguo; Tan, Shina
2013-06-01
It is well-known that cold atoms near s-wave Feshbach resonances have universal properties that are insensitive to the short-range details of the interaction. What is less known is that atoms near higher partial-wave Feshbach resonances also have remarkable universal properties. We illustrate this with a single atom interacting resonantly with two fixed static centers. At a Feshbach resonance point with orbital angular momentum L≥1, we find 2L+1 shallow bound states whose energies behave like 1/R2L+1 when the distance R between the two centers is large. We then compute corrections to the binding energies due to other parameters in the effective range expansions. For completeness we also compute the binding energies near s-wave Feshbach resonances, taking into account the corrections. Afterwards we turn to the bound states at large but finite scattering volumes. For p-wave and higher partial-wave resonances we derive a simple formula for the energies in terms of a parameter called “proximity parameter.” These results are applicable to a free atom interacting resonantly with two atoms that are localized to two lattice sites of an optical lattice, and to one light atom interacting with two heavy ones in free space. Modifications of the low energy physics due to the long range van der Waals potential are also discussed.
Resolving Difficulties of a Single-Channel Partial-Wave Analysis
NASA Astrophysics Data System (ADS)
Hunt, Brian; Manley, D. Mark
2016-03-01
The goal of our research is to determine better the properties of nucleon resonances using techniques of a global multichannel partial-wave analysis. Currently, many predicted resonances have not been found, while the properties of several known resonances are relatively uncertain. To resolve these issues, one must analyze many different reactions in a multichannel fit. Other groups generally approach this problem by generating an energy-dependent fit from the start. This is a fit where all channels are analyzed together. The method is powerful, but due to the complex nature of resonances, certain model-dependent assumptions have to be introduced from the start. The current work tries to resolve these issues by first generating single-energy solutions in which experimental data are analyzed in narrow energy bins. The single-energy solutions can then be used to constrain the energy-dependent solution in a comparatively unbiased manner. Our work focuses on adding three new single-energy solutions into the global fit. These reactions are γp --> ηp , γn --> ηn , and γp -->K+ Λ . During this talk, I will discuss the difficulties of this approach, our methods to overcome these difficulties, and a few preliminary results. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Medium Energy Nuclear Physics, under Award Nos. DE-FG02-01ER41194 and DE-SC0014323 and by the Kent State University Department of Physics.
NASA Astrophysics Data System (ADS)
Zhang, Di; Graff, Taylor; Crawford, Susan; Subramanian, Hariharan; Thompson, Sebastian; Derbas, Justin R.; Lyengar, Radha; Roy, Hemant K.; Brendler, Charles B.; Backman, Vadim
2016-02-01
Prostate Cancer (PC) is the second leading cause of cancer deaths in American men. While prostate specific antigen (PSA) test has been widely used for screening PC, >60% of the PSA detected cancers are indolent, leading to unnecessary clinical interventions. An alternative approach, active surveillance (AS), also suffer from high expense, discomfort and complications associated with repeat biopsies (every 1-3 years), limiting its acceptance. Hence, a technique that can differentiate indolent from aggressive PC would attenuate the harms from over-treatment. Combining microscopy with spectroscopy, our group has developed partial wave spectroscopic (PWS) microscopy, which can quantify intracellular nanoscale organizations (e.g. chromatin structures) that are not accessible by conventional microscopy. PWS microscopy has previously been shown to predict the risk of cancer in seven different organs (N ~ 800 patients). Herein we use PWS measurement of label-free histologically-normal prostatic epithelium to distinguish indolent from aggressive PC and predict PC risk. Our results from 38 men with low-grade PC indicated that there is a significant increase in progressors compared to non-progressors (p=0.002, effect size=110%, AUC=0.80, sensitivity=88% and specificity=72%), while the baseline clinical characteristics were not significantly different. We further improved the diagnostic power by performing nuclei-specific measurements using an automated system that separates in real-time the cell nuclei from the remaining prostate epithelium. In the long term, we envision that the PWS based prognostication can be coupled with AS without any change to the current procedure to mitigate the harms caused by over-treatment.
NASA Astrophysics Data System (ADS)
Albers, Bettina
2016-06-01
It is well known that the capillary pressure curve of partially saturated soils exhibits a hysteresis. For the same degree of saturation it has different values depending on the initial state of the soil, thus for drying of a wet soil or wetting of a dry soil. The influence of these different values of the capillary pressure on the propagation of sound waves is studied by use of a linear hyperbolic model. Even if the model does not contain a hysteresis operator, the effect of hysteresis in the capillary pressure curve is accounted for. In order to obtain the limits of phase speeds and attenuations for the two processes the correspondent values for main drying and main wetting are inserted into the model separately. This is done for two examples of soils, namely for Del Monte sand and for a silt loam both filled by an air-water mixture. The wave analysis reveals four waves: one transversal wave and three longitudinal waves. The waves which are driven by the immiscible pore fluids are influenced by the hysteresis in the capillary pressure curve while the waves which are mainly driven by the solid are not.
NASA Astrophysics Data System (ADS)
Gurka, R.; Diamessis, P.; Liberzon, A.
2009-04-01
The characterization of three-dimensional space and time-dependent coherent structures and internal waves in stratified environment is one of the most challenging tasks in geophysical fluid dynamics. Proper orthogonal decomposition (POD) is applied to 2-D slices of vorticity and horizontal divergence obtained from 3-D DNS of a stratified turbulent wake of a towed sphere at Re=5x103 and Fr=4. The numerical method employed solves the incompressible Navier-Stokes equations under the Boussinesq approximation. The temporal discretization consists of three fractional steps: an explicit advancement of the nonlinear terms, an implicit solution of the Poisson equation for the pseudo-pressure (which enforces incompressibility), and an implicit solution of the Helmholtz equation for the viscous terms (where boundary conditions are imposed). The computational domain is assumed to be periodic in the horizontal direction and non-periodic in the vertical direction. The 2-D slices are sampled along the stream-depth (Oxz), span-depth (Oyz) and stream-span planes (Oxy) for 231 times during the interval, Nt ∈ [12,35] (N is the stratification frequency). During this interval, internal wave radiation from the wake is most pronounced and the vorticity field in the wake undergoes distinct structural transitions. POD was chosen amongst the available statistical tools due to its advantage in characterization of simulated and experimentally measured velocity gradient fields. The computational procedure, applied to any random vector field, finds the most coherent feature from the given ensemble of field realizations. The decomposed empirical eigenfunctions could be referred to as "coherent structures", since they are highly correlated in an average sense with the flow field. In our analysis, we follow the computationally efficient method of 'snapshots' to find the POD eigenfunctions of the ensemble of vorticity field realizations. The results contains of the separate POD modes, along with
Das, J.N.; Paul, S.; Chakrabarti, K.
2003-04-01
Hyperspherical partial-wave theory has been applied here in a new way in the calculation of the triple differential cross sections for the ionization of hydrogen atoms by electron impact at low energies for various equal-energy-sharing kinematic conditions. The agreement of the cross section results with the recent absolute measurements of [J. Roeder, M. Baertschy, and I. Bray, Phys. Rev. A 45, 2951 (2002)] and with the latest theoretical results of the ECS and CCC calculations [J. Roeder, M. Baertschy, and I. Bray, Phys. Rev. A (to be published)] for different kinematic conditions at 17.6 eV is very encouraging. The other calculated results, for relatively higher energies, are also generally satisfactory, particularly for large {theta}{sub ab} geometries. In view of the present results, together with the fact that it is capable of describing unequal-energy-sharing kinematics [J. N. Das, J. Phys. B 35, 1165 (2002)], it may be said that the hyperspherical partial-wave theory is quite appropriate for the description of ionization events of electron-hydrogen-type systems. It is also clear that the present approach in the implementation of the hyperspherical partial-wave theory is very appropriate.
NASA Astrophysics Data System (ADS)
Klähn, Marco; Martin, Alistair; Cheong, Daniel W.; Garland, Marc V.
2013-12-01
The partial molar volumes, bar V_i, of the gas solutes H2, CO, and CO2, solvated in acetone, methanol, heptane, and diethylether are determined computationally in the limit of infinite dilution and standard conditions. Solutions are described with molecular dynamics simulations in combination with the OPLS-aa force field for solvents and customized force field for solutes. bar V_i is determined with the direct method, while the composition of bar V_i is studied with Kirkwood-Buff integrals (KBIs). Subsequently, the amount of unoccupied space and size of pre-formed cavities in pure solvents is determined. Additionally, the shape of individual solvent cages is analyzed. Calculated bar V_i deviate only 3.4 cm3 mol-1 (7.1%) from experimental literature values. Experimental bar V_i variations across solutions are reproduced qualitatively and also quantitatively in most cases. The KBI analysis identifies differences in solute induced solvent reorganization in the immediate vicinity of H2 (<0.7 nm) and solvent reorganization up to the third solvation shell of CO and CO2 (<1.6 nm) as the origin of bar V_i variations. In all solutions, larger bar V_i are found in solvents that exhibit weak internal interactions, low cohesive energy density and large compressibility. Weak internal interactions facilitate solvent displacement by thermal solute movement, which enhances the size of solvent cages and thus bar V_i. Additionally, attractive electrostatic interactions of CO2 and the solvents, which do not depend on internal solvent interactions only, partially reversed the bar V_i trends observed in H2 and CO solutions where electrostatic interactions with the solvents are absent. More empty space and larger pre-formed cavities are found in solvents with weak internal interactions, however, no evidence is found that solutes in any considered solvent are accommodated in pre-formed cavities. Individual solvent cages are found to be elongated in the negative direction of solute
Shebloski, Barbara; Conger, Katherine J; Widaman, Keith F
2005-12-01
This study examined reciprocal links between parental differential treatment, siblings' perception of partiality, and self-worth with 3 waves of data from 384 adolescent sibling dyads. Results suggest that birth-order status was significantly associated with self-worth and perception of maternal and paternal differential treatment. There was a consistent across-time effect of self-worth on perception of parental partiality for later born siblings, but not earlier born siblings, and a consistent effect of differential treatment on perception of partiality for earlier born but not later born siblings. The results contribute new insight into the associations between perception of differential parenting and adolescents' adjustment and the role of birth order. PMID:16402879
Theory of wave propagation in partially saturated double-porosity rocks: a triple-layer patchy model
NASA Astrophysics Data System (ADS)
Sun, Weitao; Ba, Jing; Carcione, José M.
2016-04-01
Wave-induced local fluid flow is known as a key mechanism to explain the intrinsic wave dissipation in fluid-saturated rocks. Understanding the relationship between the acoustic properties of rocks and fluid patch distributions is important to interpret the observed seismic wave phenomena. A triple-layer patchy (TLP) model is proposed to describe the P-wave dissipation process in a double-porosity media saturated with two immiscible fluids. The double-porosity rock consists of a solid matrix with unique host porosity and inclusions which contain the second type of pores. Two immiscible fluids are considered in concentric spherical patches, where the inner pocket and the outer sphere are saturated with different fluids. The kinetic and dissipation energy functions of local fluid flow (LFF) in the inner pocket are formulated through oscillations in spherical coordinates. The wave propagation equations of the TLP model are based on Biot's theory and the corresponding Lagrangian equations. The P-wave dispersion and attenuation caused by the Biot friction mechanism and the local fluid flow (related to the pore structure and the fluid distribution) are obtained by a plane-wave analysis from the Christoffel equations. Numerical examples and laboratory measurements indicate that P-wave dispersion and attenuation are significantly influenced by the spatial distributions of both, the solid heterogeneity and the fluid saturation distribution. The TLP model is in reasonably good agreement with White's and Johnson's models. However, differences in phase velocity suggest that the heterogeneities associated with double-porosity and dual-fluid distribution should be taken into account when describing the P-wave dispersion and attenuation in partially saturated rocks.
NASA Astrophysics Data System (ADS)
Fontaine, Fabrice R.; Ildefonse, Benoit; Bagdassarov, Nickolai S.
2005-12-01
Torsion oscillatory deformation experiments have been performed at high temperatures (600-1170°C) and over a wide range of low frequencies (20-2.10-3 Hz) on fine-grained gabbronorite samples from the Oman ophiolite in order to determine the shear wave attenuation as a function of temperature and melt fraction. The specimens have a small and uniform grain size (0.25-0.3 mm) and do not contain secondary, hydrated minerals. Measurements of internal friction (Q-1) were performed using a forced oscillatory torsion apparatus at small strains (~10-7), and with increasing small temperature steps to reduce thermal microcracking. The general dependence of Q-1 to frequency is Q-1~ω-α, where ω is the angular velocity of forced oscillations and α is an empirical exponent. Below the melting temperature (~1050°C), α has average values of ~0.15 at low frequency (<=0.5 Hz) and 0.06 at higher frequency. Above the melting temperature, α has average values of ~0.22 at low frequency and -0.02 at higher frequency. This frequency dependence of Q-1 is attributed to a viscoelastic behaviour due to the diffusion controlled grain boundary sliding, and partially to the squirt flow of the melt-phase wetting grain boundaries. The onset of melting is associated with a markedly higher Q-1 and a stronger dependence of Q-1 on temperature. The melt-related mechanical dissipation process could be a melt squirt flow. The characteristic frequency for the melt squirt flow is ωm~ 0.15-300 Hz when the melt pocket aspect ratio is ~10-3-10-2. Around the melting temperature the internal friction can be approximated by an experimental power law Q-1=A.[ω-1.d-1. exp(-Ea/RT)]α with α~ 0.08, A= 34.72s-αμm-α and Ea~ 873 kJmol-1.
Dubrovsky, V. G.; Topovsky, A. V.; Basalaev, M. Yu.
2010-09-15
The classes of exactly solvable multiline soliton potentials and corresponding wave functions of two-dimensional stationary Schroedinger equation via {partial_derivative}-dressing method are constructed and their physical interpretation is discussed.
NASA Astrophysics Data System (ADS)
Yang, Wang; Li, Yi; Wu, Congjun
2016-08-01
We systematically generalize the exotic 3He -B phase, which not only exhibits unconventional symmetry but is also isotropic and topologically nontrivial, to arbitrary partial-wave channels with multicomponent fermions. The concrete example with four-component fermions is illustrated including the isotropic f -, p -, and d -wave pairings in the spin septet, triplet, and quintet channels, respectively. The odd partial-wave channel pairings are topologically nontrivial, while pairings in even partial-wave channels are topologically trivial. The topological index reaches the largest value of N2 in the p -wave channel (N is half of the fermion component number). The surface spectra exhibit multiple linear and even high order Dirac cones. Applications to multiorbital condensed matter systems and multicomponent ultracold large spin fermion systems are discussed.
Yang, Wang; Li, Yi; Wu, Congjun
2016-08-12
We systematically generalize the exotic ^{3}He-B phase, which not only exhibits unconventional symmetry but is also isotropic and topologically nontrivial, to arbitrary partial-wave channels with multicomponent fermions. The concrete example with four-component fermions is illustrated including the isotropic f-, p-, and d-wave pairings in the spin septet, triplet, and quintet channels, respectively. The odd partial-wave channel pairings are topologically nontrivial, while pairings in even partial-wave channels are topologically trivial. The topological index reaches the largest value of N^{2} in the p-wave channel (N is half of the fermion component number). The surface spectra exhibit multiple linear and even high order Dirac cones. Applications to multiorbital condensed matter systems and multicomponent ultracold large spin fermion systems are discussed. PMID:27563972
NASA Astrophysics Data System (ADS)
Altshuler, Gennady; Manor, Ofer
2016-07-01
We use both theory and experiment to study the response of thin and free films of a partially wetting liquid to a MHz vibration, propagating in the solid substrate in the form of a Rayleigh surface acoustic wave (SAW). We generalise the previous theory for the response of a thin fully wetting liquid film to a SAW by including the presence of a small but finite three phase contact angle between the liquid and the solid. The SAW in the solid invokes a convective drift of mass in the liquid and leaks sound waves. The dynamics of a film that is too thin to support the accumulation of the sound wave leakage is governed by a balance between the drift and capillary stress alone. We use theory to demonstrate that a partially wetting liquid film, supporting a weak capillary stress, will spread along the path of the SAW. A partially wetting film, supporting an appreciable capillary stress, will however undergo a concurrent dynamic wetting and dewetting at the front and the rear, respectively, such that the film will displace, rather than spread, along the path of the SAW. The result of the theory for a weak capillary stress is in agreement with the previous experimental and theoretical studies on the response of thin silicon oil films to a propagating SAW. No corresponding previous results exist for the case of an appreciable capillary stress. We thus complement the large capillary limit of our theory by undertaking an experimental procedure where we explore the response of films of water and a surfactant solutions to a MHz SAW, which is found to be in qualitative agreement with the theory at this limit.
NASA Astrophysics Data System (ADS)
Parandaman, A.; Sudhakar, G.; Rajakumar, B.
Thermal reactions of Tetramethylsilane (TMS) diluted in argon were studied behind the reflected shock waves in a single-pulse shock tube (SPST) over the temperature range of 1085-1221 K and pressures varied between 10.6 and 22.8 atm. The stable products resulting from the decomposition of TMS were identified and quantified using gas chromatography and also verified with Fourier Transform Infrared (FTIR) spectrometer. The major reaction products are methane (CH4) and ethylene (C2H4). The minor reaction products are ethane (C2H6) and propylene (C3H6). The initiation of mechanism in the decomposition of TMS takes plays via the Si-C bond scission by ejecting the methyl radicals (CH3) and trimethylsilyl radicals ((CH3)3Si). The measured temperature dependent rate coefficient for the total decomposition of TMS was to be ktotal = 1.66 ×1015 exp (-64.46/RT) s-1 and for the formation of CH4 reaction channel was to be k = 2.20 × 1014 exp (-60.15/RT) s-1, where the activation energies are given in kcal mol-1. A kinetic scheme containing 17 species and 28 elementary reactions was used for the simulation using chemical kinetic simulator over the temperature range of 1085-1221 K. The agreement between the experimental and simulated results was satisfactory.
Henao-Escobar, W; Domínguez-Renedo, O; Alonso-Lomillo, M A; Arcos-Martínez, M J
2015-10-01
This work presents the simultaneous determination of cadaverine, histamine, putrescine and tyramine by square wave voltammetry using a boron-doped diamond electrode. A multivariate calibration method based on partial least square regressions has allowed the resolution of the very high overlapped voltammetric signals obtained for the analyzed biogenic amines. Prediction errors lower than 9% have been obtained when concentration of quaternary mixtures were calculated. The developed procedure has been applied in the analysis of ham samples, which results are in good agreement with those obtained using the standard HPLC method. PMID:26078134
Salgado, Carlos W.; Weygand, Dennis P.
2014-04-01
Meson spectroscopy is going through a revival with the advent of high statistics experiments and new advances in the theoretical predictions. The Constituent Quark Model (CQM) is finally being expanded considering more basic principles of field theory and using discrete calculations of Quantum Chromodynamics (lattice QCD). These new calculations are approaching predictive power for the spectrum of hadronic resonances and decay modes. It will be the task of the new experiments to extract the meson spectrum from the data and compare with those predictions. The goal of this report is to describe one particular technique for extracting resonance information from multiparticle final states. The technique described here, partial wave analysis based on the helicity formalism, has been used at Brookhaven National Laboratory (BNL) using pion beams, and Jefferson Laboratory (Jlab) using photon beams. In particular this report broaden this technique to include production experiments using linearly polarized real photons or quasi-real photons. This article is of a didactical nature. We describe the process of analysis, detailing assumptions and formalisms, and is directed towards people interested in starting partial wave analysis.
NASA Astrophysics Data System (ADS)
Salgado, Carlos W.; Weygand, Dennis P.
2014-04-01
Meson spectroscopy is going through a revival with the advent of high statistics experiments and new advances in the theoretical predictions. The Constituent Quark Model (CQM) is finally being expanded considering more basic principles of field theory and using discrete calculations of Quantum Chromodynamics (lattice QCD). These new calculations are approaching predictive power for the spectrum of hadronic resonances and decay modes. It will be the task of the new experiments to extract the meson spectrum from the data and compare with those predictions. The goal of this report is to describe one particular technique for extracting resonance information from multiparticle final states. The technique described here, partial wave analysis based on the helicity formalism, has been used at Brookhaven National Laboratory (BNL) using pion beams, and Jefferson Laboratory (JLab) using photon beams. In particular this report broadens this technique to include production experiments using linearly polarized real photons or quasi-real photons. This article is of a didactical nature. We describe the process of analysis, detailing assumptions and formalisms, and is directed towards people interested in starting partial wave analysis.
NASA Astrophysics Data System (ADS)
Nakayama, M.; Kawakata, H.; Doi, I.; Takahashi, N.
2015-12-01
Recently, landslides due to heavy rain and/or earthquakes have been increasing and severe damage occurred in Japan in some cases (e.g., Chigira et al., 2013, Geomorph.). One of the principle factors activating landslides is groundwater. Continuous measurements of moisture in soil and/or pore pressure are performed to investigate the groundwater behavior. However, such measurements give information on only local behavior of the groundwater. To monitor the state of target slope, it is better to measure signals affected by the behavior of groundwater in a widely surrounding region. The elastic waves propagating through the medium under the target slope are one of candidates of such signals. In this study, we measure propagating waves through a sand soil made in laboratory, injecting water into it from the bottom. We investigate the characteristics of the propagating waves. We drop sand particles in a container (750 mm long, 300 mm wide and 400 mm high) freely and made a sand soil. The sand soil consists of two layers. One is made of larger sand particles (0.2-0.4 mm in diameter) and the other is made of smaller sand particles (0.05-0.2 mm in diameter). The dry density of these sand layers is about 1.45 g/cm3. We install a shaker for generating elastic waves, accelerometers and pore pressure gauges in the sand soil. We apply small voltage steps repeatedly, and we continuously measure elastic waves propagating through the sand soil at a sampling rate of 51.2 ksps for a period including the water injection period. We estimate the spatio-temporal variation in the maximum cross-correlation coefficients and the corresponding time lags, using template waveforms recorded in the initial period as references. The coefficient for the waveforms recorded at the accelerometer attached to the tip of the shaker is almost stable in high values with a slight decrease down to 0.94 in the period when the sand particles around the shaker are considered to become wet. On the other hand
Partial wave analysis of J/ψ-->γ(K+K- π0)
NASA Astrophysics Data System (ADS)
BES Collaboration; Bai, J. Z.; Bian, J. G.; Chai, Z. W.; Chen, G. P.; Chen, H. F.; Chen, J. C.; Chen, Y.; Chen, Y. B.; Chen, Y. Q.; Cheng, B. S.; Cui, X. Z.; Ding, H. L.; Dong, L. Y.; Du, Z. Z.; Feng, S.; Gao, C. S.; Gao, M. L.; Gao, S. Q.; Gu, J. H.; Gu, S. D.; Gu, W. X.; Gu, Y. F.; Guo, Y. N.; Guo, Z. J.; Han, S. W.; Han, Y.; He, J.; He, J. T.; He, M.; Hu, G. Y.; Hu, H. M.; Hu, J. L.; Hu, Q. H.; Hu, T.; Hu, X. Q.; Huang, J. D.; Huang, Y. Z.; Jiang, C. H.; Jin, Y.; Ke, Z. J.; Lai, Y. F.; Lang, P. F.; Li, C. G.; Li, D.; Li, H. B.; Li, J.; Li, P. Q.; Li, R. B.; Li, W.; Li, W. D.; Li, W. G.; Li, X. H.; Li, X. N.; Liu, H. M.; Liu, J.; Liu, J. H.; Liu, R. G.; Liu, Y.; Lu, F.; Lu, J. G.; Lu, J. Y.; Lu, L. C.; Luo, C. H.; Ma, A. M.; Ma, E. C.; Ma, J. M.; Mao, H. S.; Mao, Z. P.; Meng, X. C.; Nie, J.; Qi, N. D.; Qi, X. R.; Qian, C. D.; Qiu, J. F.; Qu, Y. H.; Que, Y. K.; Rong, G.; Shao, Y. Y.; Shen, B. W.; Shen, D. L.; Shen, H.; Shen, X. Y.; Sheng, H. Y.; Shi, H. Z.; Song, X. F.; Sun, F.; Sun, H. S.; Tang, S. Q.; Tong, G. L.; Wang, F.; Wang, L. S.; Wang, L. Z.; Wang, M.; Wang, Meng; Wang, P.; Wang, P. L.; Wang, S. M.; Wang, T. J.; Wang, Y. Y.; Wei, C. L.; Wu, Y. G.; Xi, D. M.; Xia, X. M.; Xie, P. P.; Xie, Y.; Xie, Y. H.; Xiong, W. J.; Xu, C. C.; Xu, G. F.; Xue, S. T.; Yan, J.; Yan, W. G.; Yang, C. M.; Yang, C. Y.; Yang, J.; Yang, X. F.; Ye, M. H.; Ye, S. W.; Ye, Y. X.; Yi, K.; Yu, C. S.; Yu, C. X.; Yu, Y. H.; Yu, Z. Q.; Yu, Z. T.; Yuan, C. Z.; Yuan, Y.; Zhang, B. Y.; Zhang, C. C.; Zhang, D. H.; Zhang, Dehong; Zhang, H. L.; Zhang, J.; Zhang, J. L.; Zhang, J. W.; Zhang, L. S.; Zhang, Q. J.; Zhang, S. Q.; Zhang, X. Y.; Zhang, Y.; Zhang, Y. Y.; Zhao, D. X.; Zhao, H. W.; Zhao, J. W.; Zhao, M.; Zhao, W. R.; Zhao, Z. G.; Zheng, J. P.; Zheng, L. S.; Zheng, Z. P.; Zhou, G. P.; Zhou, H. S.; Zhou, L.; Zhu, Q. M.; Zhu, Y. C.; Zhu, Y. S.; Zhuang, B. A.; Bugg, D. V.; Sarantsev, A. V.; Zou, B. S.
1998-11-01
BES data on J/ψ-->γ(K+K-π0) display a strong peak in the K+K-π0 mass spectrum at 1450 MeV. This peak and a corresponding one in J/ψ-->γ(ηπ+π-) at ~1400 MeV may be fitted well by η(1440) with dominant decays to K*(890)K, using an s-dependent width in the Breit-Wigner amplitude. A broad background is also required in KK0 (where K0 stands for the Kπ S-wave) and also in ηππ, but is probably not resonant in this mass range.
On-shell coupled-channel approach to proton-hydrogen collisions without partial-wave expansion
Kadyrov, A. S.; Bray, I.; Stelbovics, A. T.
2006-01-15
A fully quantal approach to proton collisions with hydrogen based on the atomic-orbital close-coupling method is presented. The method leads to a system of coupled three-dimensional momentum-space integral equations for the scattering amplitudes. These equations are reduced to two-dimensional ones using an on-shell approximation. Furthermore, by considering the symmetry of the problem, we demonstrate that these can be reduced to just one dimension. The resulting equations are solved without partial-wave expansion. Cross sections for electron transfer in proton collisions with the ground state of atomic hydrogen are calculated and shown to agree well with experiment over a wide energy range.
NASA Astrophysics Data System (ADS)
Farsaei, Amir Ashkan; Mokhtari-Koushyar, Farzad; Javad Seyed-Talebi, Seyed Mohammad; Kavehvash, Zahra; Shabany, Mahdi
2016-03-01
Active millimeter-wave imaging based on synthetic aperture focusing offers certain unique and practical advantages in nondestructive testing applications. Traditionally, the imaging for this purpose is performed through a long procedure of raster scanning with a single antenna across a two-dimensional grid, leading to a slow, bulky, and expensive scanning platform. In this paper, an improved bistatic structure based on radial compressive sensing is proposed, where one fixed transmitter antenna and a linear array of receiving antennas are used. The main contributions of this paper are (a) reducing the scanning time, (b) improving the output quality, and (c) designing an inexpensive setup. These improvements are the result of the underlying proposed simpler scanning structure and faster reconstruction process.
Effects of partial liquid/gas saturation on extensional wave attenuation in Berea sandstone
NASA Astrophysics Data System (ADS)
Yin, C.-S.; Batzle, M. L.; Smith, B. J.
1992-07-01
Extensional wave attenuation measurements on Berea sandstone were made during increasing (imbibition) and decreasing (drainage) brine saturations. Measurements on samples with both open-pore and closed-pore surfaces were made using the resonant-bar technique. The frequency dependence was examined using the forced-deformation method. The attenuation was found to be dependent on saturation history as well as degree of saturation and boundary flow conditions. The sample with open-pore surface had a larger attenuation which peaked at greater brine saturations than the sample with closed-pore surface. During drainage, the attenuation reached a maximum at about 90% brine saturation as opposed to about 97% brine saturation during imbibition. The variation of the size and number of air pockets within the rock can account for this discrepancy. The magnitude of the attenuation peak value decreases substantially with decreasing frequency to the extent that no attenuation peak with saturation was apparent at seismic frequencies, say, below 100 Hz.
NASA Technical Reports Server (NTRS)
Bean, T. A.; Bowhill, S. A.
1973-01-01
Partial-reflection data collected for the eclipse of July 10, 1972 as well as for July 9 and 11, 1972, are analyzed to determine eclipse effects on D-region electron densities. The partial-reflection experiment was set up to collect data using an on-line PDP-15 computer and DECtape storage. The electron-density profiles show good agreement with results from other eclipses. The partial-reflection programs were changed after the eclipse data collection to improve the operation of the partial-reflection system. These changes were mainly due to expanded computer hardware and have simplified the operations of the system considerably.
NASA Astrophysics Data System (ADS)
Rolland, Joran; Domeisen, Daniela I. V.
2016-04-01
Many geophysical waves in the atmosphere or in the ocean have a three dimensional structure and contain a range of scales. This is for instance the case of planetary waves in the stratosphere connected to baroclinic eddies in the troposphere [1]. In the study of such waves from reanalysis data or output of numerical simulations, Empirical Orthogonal Functions (EOF) obtained as a Proper Orthogonal Decomposition of the data sets have been of great help. However, most of these computations rely on the diagonalisation of space correlation matrices: this means that the considered data set can only have a limited number of gridpoints. The main consequence is that such analyses are often only performed in planes (as function of height and latitude, or longitude and latitude for instance), which makes the educing of the three dimensional structure of the wave quite difficult. In the case of the afore mentionned waves, the matter of the longitudinal dependence or the proper correlation between modes through the tropopause is an open question. An elegant manner to circumvent this problem is to consider the output of the Orthogonal Decomposition as a whole. Indeed, it has been shown that the normalised time series of the amplitude of each EOF, far from just being decorrelated from one another, are actually another set of orthogonal functions. These can actually be computed through the diagonlisation of the time correlation matrix of the data set, just like the EOF were the result of the diagonalisation of the space correlation matrix. The signal is then fully decomposed in the framework of the Bi-Orthogonal Decomposition as the sum of the nth explained variance, time the nth eigenmode of the time correlation times the nth eigenmode of the spacial correlations [2,3]. A practical consequence of this result is that the EOF can be reconstructed from the projection of the dataset onto the eigenmodes of the time correlation matrix in the so-called snapshot method [4]. This is very
NASA Astrophysics Data System (ADS)
Rolland, Joran; Domeisen, Daniela I. V.
2016-04-01
Many geophysical waves in the atmosphere or in the ocean have a three dimensional structure and contain a range of scales. This is for instance the case of planetary waves in the stratosphere connected to baroclinic eddies in the troposphere [1]. In the study of such waves from reanalysis data or output of numerical simulations, Empirical Orthogonal Functions (EOF) obtained as a Proper Orthogonal Decomposition of the data sets have been of great help. However, most of these computations rely on the diagonalisation of space correlation matrices: this means that the considered data set can only have a limited number of gridpoints. The main consequence is that such analyses are often only performed in planes (as function of height and latitude, or longitude and latitude for instance), which makes the educing of the three dimensional structure of the wave quite difficult. In the case of the afore mentionned waves, the matter of the longitudinal dependence or the proper correlation between modes through the tropopause is an open question. An elegant manner to circumvent this problem is to consider the output of the Orthogonal Decomposition as a whole. Indeed, it has been shown that the normalised time series of the amplitude of each EOF, far from just being decorrelated from one another, are actually another set of orthogonal functions. These can actually be computed through the diagonlisation of the time correlation matrix of the data set, just like the EOF were the result of the diagonalisation of the space correlation matrix. The signal is then fully decomposed in the framework of the Bi-Orthogonal Decomposition as the sum of the nth explained variance, time the nth eigenmode of the time correlation times the nth eigenmode of the spacial correlations [2,3]. A practical consequence of this result is that the EOF can be reconstructed from the projection of the dataset onto the eigenmodes of the time correlation matrix in the so-called snapshot method [4]. This is very
Quantization of wave equations and hermitian structures in partial differential varieties
Paneitz, S. M.; Segal, I. E.
1980-01-01
Sufficiently close to 0, the solution variety of a nonlinear relativistic wave equation—e.g., of the form □ϕ + m2ϕ + gϕp = 0—admits a canonical Lorentz-invariant hermitian structure, uniquely determined by the consideration that the action of the differential scattering transformation in each tangent space be unitary. Similar results apply to linear time-dependent equations or to equations in a curved asymptotically flat space-time. A close relation of the Riemannian structure to the determination of vacuum expectation values is developed and illustrated by an explicit determination of a perturbative 2-point function for the case of interaction arising from curvature. The theory underlying these developments is in part a generalization of that of M. G. Krein and collaborators concerning stability of differential equations in Hilbert space and in part a precise relation between the unitarization of given symplectic linear actions and their full probabilistic quantization. The unique causal structure in the infinite symplectic group is instrumental in these developments. PMID:16592923
NASA Astrophysics Data System (ADS)
Salvat, Francesc; Jablonski, Aleksander; Powell, Cedric J.
2005-01-01
The FORTRAN 77 code system ELSEPA for the calculation of elastic scattering of electrons and positrons by atoms, positive ions and molecules is presented. These codes perform relativistic (Dirac) partial-wave calculations for scattering by a local central interaction potential V(r). For atoms and ions, the static-field approximation is adopted, with the potential set equal to the electrostatic interaction energy between the projectile and the target, plus an approximate local exchange interaction when the projectile is an electron. For projectiles with kinetic energies up to 10 keV, the potential may optionally include a semiempirical correlation-polarization potential to describe the effect of the target charge polarizability. Also, for projectiles with energies less than 1 MeV, an imaginary absorptive potential can be introduced to account for the depletion of the projectile wave function caused by open inelastic channels. Molecular cross sections are calculated by means of a single-scattering independent-atom approximation in which the electron density of a bound atom is approximated by that of the free neutral atom. Elastic scattering by individual atoms in solids is described by means of a muffin-tin model potential. Partial-wave calculations are feasible on modest personal computers for energies up to about 5 MeV. The ELSEPA code also implements approximate factorization methods that allow the fast calculation of elastic cross sections for much higher energies. The interaction model adopted in the calculations is defined by the user by combining the different options offered by the code. The nuclear charge distribution can be selected among four analytical models (point nucleus, uniformly charged sphere, Fermi's distribution and Helm's uniform-uniform distribution). The atomic electron density is handled in numerical form. The distribution package includes data files with electronic densities of neutral atoms of the elements hydrogen to lawrencium ( Z=1
NASA Astrophysics Data System (ADS)
Sidler, Rolf; Carcione, José M.; Holliger, Klaus
2013-02-01
We present a novel numerical approach for the comprehensive, flexible, and accurate simulation of poro-elastic wave propagation in 2D polar coordinates. An important application of this method and its extensions will be the modeling of complex seismic wave phenomena in fluid-filled boreholes, which represents a major, and as of yet largely unresolved, computational problem in exploration geophysics. In view of this, we consider a numerical mesh, which can be arbitrarily heterogeneous, consisting of two or more concentric rings representing the fluid in the center and the surrounding porous medium. The spatial discretization is based on a Chebyshev expansion in the radial direction and a Fourier expansion in the azimuthal direction and a Runge-Kutta integration scheme for the time evolution. A domain decomposition method is used to match the fluid-solid boundary conditions based on the method of characteristics. This multi-domain approach allows for significant reductions of the number of grid points in the azimuthal direction for the inner grid domain and thus for corresponding increases of the time step and enhancements of computational efficiency. The viability and accuracy of the proposed method has been rigorously tested and verified through comparisons with analytical solutions as well as with the results obtained with a corresponding, previously published, and independently benchmarked solution for 2D Cartesian coordinates. Finally, the proposed numerical solution also satisfies the reciprocity theorem, which indicates that the inherent singularity associated with the origin of the polar coordinate system is adequately handled.
Sidler, Rolf; Carcione, José M.; Holliger, Klaus
2013-02-15
We present a novel numerical approach for the comprehensive, flexible, and accurate simulation of poro-elastic wave propagation in 2D polar coordinates. An important application of this method and its extensions will be the modeling of complex seismic wave phenomena in fluid-filled boreholes, which represents a major, and as of yet largely unresolved, computational problem in exploration geophysics. In view of this, we consider a numerical mesh, which can be arbitrarily heterogeneous, consisting of two or more concentric rings representing the fluid in the center and the surrounding porous medium. The spatial discretization is based on a Chebyshev expansion in the radial direction and a Fourier expansion in the azimuthal direction and a Runge–Kutta integration scheme for the time evolution. A domain decomposition method is used to match the fluid–solid boundary conditions based on the method of characteristics. This multi-domain approach allows for significant reductions of the number of grid points in the azimuthal direction for the inner grid domain and thus for corresponding increases of the time step and enhancements of computational efficiency. The viability and accuracy of the proposed method has been rigorously tested and verified through comparisons with analytical solutions as well as with the results obtained with a corresponding, previously published, and independently benchmarked solution for 2D Cartesian coordinates. Finally, the proposed numerical solution also satisfies the reciprocity theorem, which indicates that the inherent singularity associated with the origin of the polar coordinate system is adequately handled.
Das, J.N.; Paul, S.; Chakrabarti, K.
2004-04-01
Here we report a set of converged cross-section results for double photoionization of helium atoms obtained in the hyperspherical partial wave theory for equal energy sharing kinematics at 6 eV energy above threshold. The calculated cross section results are generally in excellent agreement with the absolute measured results of Doerner et al. [Phys. Rev. 57, 1074 (1998)].
Shock wave study and theoretical modeling of the thermal decomposition of c-C4F8.
Cobos, C J; Hintzer, K; Sölter, L; Tellbach, E; Thaler, A; Troe, J
2015-12-28
The thermal dissociation of octafluorocyclobutane, c-C4F8, was studied in shock waves over the range 1150-2300 K by recording UV absorption signals of CF2. It was found that the primary reaction nearly exclusively produces 2 C2F4 which afterwards decomposes to 4 CF2. A primary reaction leading to CF2 + C3F6 is not detected (an upper limit to the yield of the latter channel was found to be about 10 percent). The temperature range of earlier single pulse shock wave experiments was extended. The reaction was shown to be close to its high pressure limit. Combining high and low temperature results leads to a rate constant for the primary dissociation of k1 = 10(15.97) exp(-310.5 kJ mol(-1)/RT) s(-1) in the range 630-1330 K, over which k1 varies over nearly 14 orders of magnitude. Calculations of the energetics of the reaction pathway and the rate constants support the conclusions from the experiments. Also they shed light on the role of the 1,4-biradical CF2CF2CF2CF2 as an intermediate of the reaction. PMID:26577435
Partial wave analysis of the reaction {gamma}p{yields}p{omega} and the search for nucleon resonances
Williams, M.; Applegate, D.; Bellis, M.; Meyer, C. A.; Dey, B; Dickson, R.; Krahn, Z.; McCracken, M. E.; Moriya, K.; Schumacher, R. A.; Adhikari, K. P.; Careccia, S. L.; Dodge, G. E.; Guler, N.; Klein, A.; Mayer, M.; Nepali, C. S.; Niroula, M. R.; Seraydaryan, H.; Tkachenko, S.
2009-12-15
An event-based partial wave analysis (PWA) of the reaction {gamma}p{yields}p{omega} has been performed on a high-statistics dataset obtained using the CLAS at Jefferson Lab for center-of-mass energies from threshold up to 2.4 GeV. This analysis benefits from access to the world's first high-precision spin-density matrix element measurements, available to the event-based PWA through the decay distribution of {omega}{yields}{pi}{sup +}{pi}{sup -}{pi}{sup 0}. The data confirm the dominance of the t-channel {pi}{sup 0} exchange amplitude in the forward direction. The dominant resonance contributions are consistent with the previously identified states F{sub 15}(1680) and D{sub 13}(1700) near threshold, as well as the G{sub 17}(2190) at higher energies. Suggestive evidence for the presence of a J{sup P}=5/2{sup +} state around 2 GeV, a ''missing'' state, has also been found. Evidence for other states is inconclusive.
Partial wave analysis of the reaction γp→pω and the search for nucleon resonances
Williams, M.; Applegate, D.; Bellis, M.; Meyer, C. A.; Adhikari, K. P.; Anghinolfi, M.; Baghdasaryan, H.; Ball, J.; Battaglieri, M.; Bedlinskiy, I.; et al
2009-12-30
We performed an event-based partial wave analysis (PWA) of the reaction γ p -> p ω on a high-statistics dataset obtained using the CLAS at Jefferson Lab for center-of-mass energies from threshold up to 2.4 GeV. This analysis benefits from access to the world's first high precision spin density matrix element measurements, available to the event-based PWA through the decay distribution of omega-> π+ π - π0. The data confirm the dominance of the t-channel π0 exchange amplitude in the forward direction. The dominant resonance contributions are consistent with the previously identified states F[15](1680) and D[13](1700) near threshold, as wellmore » as the G[17](2190) at higher energies. Suggestive evidence for the presence of a J(P)=5/2+ state around 2 GeV, a "missing" state, has also been found. Evidence for other states is inconclusive.« less
Partial wave analysis of the reaction γp→pω and the search for nucleon resonances
NASA Astrophysics Data System (ADS)
Williams, M.; Applegate, D.; Bellis, M.; Meyer, C. A.; Adhikari, K. P.; Anghinolfi, M.; Baghdasaryan, H.; Ball, J.; Battaglieri, M.; Bedlinskiy, I.; Berman, B. L.; Biselli, A. S.; Briscoe, W. J.; Brooks, W. K.; Burkert, V. D.; Careccia, S. L.; Carman, D. S.; Cole, P. L.; Collins, P.; Crede, V.; D'Angelo, A.; Daniel, A.; de Vita, R.; de Sanctis, E.; Deur, A.; Dey, B.; Dhamija, S.; Dickson, R.; Djalali, C.; Dodge, G. E.; Doughty, D.; Dugger, M.; Dupre, R.; Alaoui, A. El; Elouadrhiri, L.; Eugenio, P.; Fedotov, G.; Fegan, S.; Fradi, A.; Gabrielyan, M. Y.; Garçon, M.; Gilfoyle, G. P.; Giovanetti, K. L.; Girod, F. X.; Gohn, W.; Golovatch, E.; Gothe, R. W.; Griffioen, K. A.; Guidal, M.; Guler, N.; Guo, L.; Hafidi, K.; Hakobyan, H.; Hanretty, C.; Hassall, N.; Hicks, K.; Holtrop, M.; Ilieva, Y.; Ireland, D. G.; Ishkhanov, B. S.; Isupov, E. L.; Jawalkar, S. S.; Jo, H. S.; Johnstone, J. R.; Joo, K.; Keller, D.; Khandaker, M.; Khetarpal, P.; Kim, W.; Klein, A.; Klein, F. J.; Krahn, Z.; Kubarovsky, V.; Kuleshov, S. V.; Kuznetsov, V.; Livingston, K.; Lu, H. Y.; Mayer, M.; McAndrew, J.; McCracken, M. E.; McKinnon, B.; Mirazita, M.; Mokeev, V.; Moreno, B.; Moriya, K.; Morrison, B.; Munevar, E.; Nadel-Turonski, P.; Nepali, C. S.; Niccolai, S.; Niculescu, G.; Niculescu, I.; Niroula, M. R.; Niyazov, R. A.; Osipenko, M.; Ostrovidov, A. I.; Paris, M.; Park, K.; Park, S.; Pasyuk, E.; Pereira, S. Anefalos; Perrin, Y.; Pisano, S.; Pogorelko, O.; Pozdniakov, S.; Price, J. W.; Procureur, S.; Protopopescu, D.; Ricco, G.; Ripani, M.; Ritchie, B. G.; Rosner, G.; Rossi, P.; Sabatié, F.; Saini, M. S.; Salamanca, J.; Salgado, C.; Schott, D.; Schumacher, R. A.; Seraydaryan, H.; Sharabian, Y. G.; Smith, E. S.; Sober, D. I.; Sokhan, D.; Stepanyan, S. S.; Stoler, P.; Strakovsky, I. I.; Strauch, S.; Taiuti, M.; Tedeschi, D. J.; Tkachenko, S.; Ungaro, M.; Vineyard, M. F.; Voutier, E.; Watts, D. P.; Weygand, D. P.; Wood, M. H.; Zhang, J.; Zhao, B.
2009-12-01
An event-based partial wave analysis (PWA) of the reaction γp→pω has been performed on a high-statistics dataset obtained using the CLAS at Jefferson Lab for center-of-mass energies from threshold up to 2.4 GeV. This analysis benefits from access to the world’s first high-precision spin-density matrix element measurements, available to the event-based PWA through the decay distribution of ω→π+π-π0. The data confirm the dominance of the t-channel π0 exchange amplitude in the forward direction. The dominant resonance contributions are consistent with the previously identified states F15(1680) and D13(1700) near threshold, as well as the G17(2190) at higher energies. Suggestive evidence for the presence of a JP=5/2+ state around 2 GeV, a “missing” state, has also been found. Evidence for other states is inconclusive.
Batakliev, Todor; Georgiev, Vladimir; Anachkov, Metody; Rakovsky, Slavcho
2014-01-01
Catalytic ozone decomposition is of great significance because ozone is a toxic substance commonly found or generated in human environments (aircraft cabins, offices with photocopiers, laser printers, sterilizers). Considerable work has been done on ozone decomposition reported in the literature. This review provides a comprehensive summary of the literature, concentrating on analysis of the physico-chemical properties, synthesis and catalytic decomposition of ozone. This is supplemented by a review on kinetics and catalyst characterization which ties together the previously reported results. Noble metals and oxides of transition metals have been found to be the most active substances for ozone decomposition. The high price of precious metals stimulated the use of metal oxide catalysts and particularly the catalysts based on manganese oxide. It has been determined that the kinetics of ozone decomposition is of first order importance. A mechanism of the reaction of catalytic ozone decomposition is discussed, based on detailed spectroscopic investigations of the catalytic surface, showing the existence of peroxide and superoxide surface intermediates. PMID:26109880
Batakliev, Todor; Georgiev, Vladimir; Anachkov, Metody; Rakovsky, Slavcho; Zaikov, Gennadi E
2014-06-01
Catalytic ozone decomposition is of great significance because ozone is a toxic substance commonly found or generated in human environments (aircraft cabins, offices with photocopiers, laser printers, sterilizers). Considerable work has been done on ozone decomposition reported in the literature. This review provides a comprehensive summary of the literature, concentrating on analysis of the physico-chemical properties, synthesis and catalytic decomposition of ozone. This is supplemented by a review on kinetics and catalyst characterization which ties together the previously reported results. Noble metals and oxides of transition metals have been found to be the most active substances for ozone decomposition. The high price of precious metals stimulated the use of metal oxide catalysts and particularly the catalysts based on manganese oxide. It has been determined that the kinetics of ozone decomposition is of first order importance. A mechanism of the reaction of catalytic ozone decomposition is discussed, based on detailed spectroscopic investigations of the catalytic surface, showing the existence of peroxide and superoxide surface intermediates. PMID:26109880
Spin-wave propagation and transformation in a thermal gradient
NASA Astrophysics Data System (ADS)
Obry, Björn; Vasyuchka, Vitaliy I.; Chumak, Andrii V.; Serga, Alexander A.; Hillebrands, Burkard
2012-11-01
The influence of a thermal gradient on the propagation properties of externally excited dipolar spin waves in a magnetic insulator waveguide is investigated. It is shown that spin waves propagating towards a colder region along the magnetization direction continuously reduce their wavelength. The wavelength increase of a wave propagating into a hotter region was utilized to realize its decomposition in the partial waveguide modes which are reflected at different locations. This influence of temperature on spin-wave properties is mainly caused by a change in the saturation magnetization and yields promising opportunities for the manipulation of spin waves in spin-caloritronic applications.
Physics of Partially Ionized Plasmas
NASA Astrophysics Data System (ADS)
Krishan, Vinod
2016-05-01
Figures; Preface; 1. Partially ionized plasmas here and everywhere; 2. Multifluid description of partially ionized plasmas; 3. Equilibrium of partially ionized plasmas; 4. Waves in partially ionized plasmas; 5. Advanced topics in partially ionized plasmas; 6. Research problems in partially ionized plasmas; Supplementary matter; Index.
NASA Astrophysics Data System (ADS)
Chrysos, Michael
2016-03-01
Relying on a simple analytic two-atom model in which the anisotropy of the interaction dipole polarizability obeys an inverse power law as a function of separation, we offer mathematical and numerical evidence that, in a monoatomic gas, the free-free Raman spectrum for a collisional pair of two different isotopes, a-a', may vastly differ from that for a-a. This result is obtained even if a and a' are assumed to have the same mass and zero nuclear spin and even if a-a and a-a' are subject to the same interaction polarizability and potential. The mechanism responsible for this effect is inherent in the parity of the partial-wave rotational quantum number J: given that the contribution of each partial wave to the Raman cross section is controlled by a polarizability-transition matrix-element and that each of those matrix-elements has a radial component with a magnitude slightly smaller than that of the preceding partial wave, a deficit which disfavors the odd-numbered waves is accumulated upon summing over J. In the far high-frequency wing, this deficit tends to generate spectral intensities for a-a' about half as great as the a-a ones, a tendency which becomes all the more effective as temperature is decreased. We show for instance that, for the spectral branch ΔJ = 2, the fractional difference between the free-free differential cross sections for a-a and a-a' is /1 2 /( 1 - x2 ) 3 1 + 3 x 4 , with x = √{ E / E ' } (E (E') being the initial (final) state energy of the pair and E' - E = hcν (ν > 0)). Remarkably, this quantity is zero at ν ≈ 0 but goes to /1 2 for ν ≫ 0. For ΔJ = 0, analogous conclusions may be drawn from the expression ( 1 + /ln ( 1+x/1-x ) 2 arctan x ) - 1 .
ERIC Educational Resources Information Center
Napier, J.
1988-01-01
Outlines the role of the main organisms involved in woodland decomposition and discusses some of the variables affecting the rate of nutrient cycling. Suggests practical work that may be of value to high school students either as standard practice or long-term projects. (CW)
Some nonlinear space decomposition algorithms
Tai, Xue-Cheng; Espedal, M.
1996-12-31
Convergence of a space decomposition method is proved for a general convex programming problem. The space decomposition refers to methods that decompose a space into sums of subspaces, which could be a domain decomposition or a multigrid method for partial differential equations. Two algorithms are proposed. Both can be used for linear as well as nonlinear elliptic problems and they reduce to the standard additive and multiplicative Schwarz methods for linear elliptic problems. Two {open_quotes}hybrid{close_quotes} algorithms are also presented. They converge faster than the additive one and have better parallelism than the multiplicative method. Numerical tests with a two level domain decomposition for linear, nonlinear and interface elliptic problems are presented for the proposed algorithms.
NASA Astrophysics Data System (ADS)
Elboudali, F.; Joulakian, B.
2001-12-01
The (e, 2e) ionization of diatomic lithium Li2 by fast electrons is studied by applying, for the slow ejected electron, an asymptotically exact partial-wave description, which takes into account the diatomic nature of the problem. The ionization is considered as a vertical transition from the lowest vibrational and rotational level of the fundamental electronic state 1Σg+ of Li2 to the fundamental 2Σg+ state of Li2+. After verification of the procedure on the (e, 2e) ionization of diatomic hydrogen H2 for which experimental and theoretical results exist we present the particularities and favourable directions for Li2 targets.
Hammani, Kamal; Finot, Christophe; Millot, Guy
2009-04-15
We present experimental and theoretical results showing efficient emergence of rogue wavelike extreme intensity spikes during the fiber-based induced-modulational instability process driven by a partially incoherent pump. In particular, we show that the rogue event probability can be easily controlled by adjusting the pump-signal detuning. PMID:19370096
Chrysos, Michael
2016-03-21
Relying on a simple analytic two-atom model in which the anisotropy of the interaction dipole polarizability obeys an inverse power law as a function of separation, we offer mathematical and numerical evidence that, in a monoatomic gas, the free-free Raman spectrum for a collisional pair of two different isotopes, a-a', may vastly differ from that for a-a. This result is obtained even if a and a' are assumed to have the same mass and zero nuclear spin and even if a-a and a-a' are subject to the same interaction polarizability and potential. The mechanism responsible for this effect is inherent in the parity of the partial-wave rotational quantum number J: given that the contribution of each partial wave to the Raman cross section is controlled by a polarizability-transition matrix-element and that each of those matrix-elements has a radial component with a magnitude slightly smaller than that of the preceding partial wave, a deficit which disfavors the odd-numbered waves is accumulated upon summing over J. In the far high-frequency wing, this deficit tends to generate spectral intensities for a-a' about half as great as the a-a ones, a tendency which becomes all the more effective as temperature is decreased. We show for instance that, for the spectral branch ΔJ = 2, the fractional difference between the free-free differential cross sections for a-a and a-a' is 12(1-x(2))(3)1+3x(4), with x=√[E/E(')] (E (E') being the initial (final) state energy of the pair and E' - E = hcν (ν > 0)). Remarkably, this quantity is zero at ν ≈ 0 but goes to 12 for ν ≫ 0. For ΔJ = 0, analogous conclusions may be drawn from the expression (1+ln(1+x1-x)2arctanx)(-1). PMID:27004860
NASA Astrophysics Data System (ADS)
Brajanovski, Miroslav; Müller, Tobias M.; Parra, Jorge O.
2010-08-01
In this work we interpret the data showing unusually strong velocity dispersion of P-waves (up to 30%) and attenuation in a relatively narrow frequency range. The cross-hole and VSP data were measured in a reservoir, which is in the porous zone of the Silurian Kankakee Limestone Formation formed by vertical fractures within a porous matrix saturated by oil, and gas patches. Such a medium exhibits significant attenuation due to wave-induced fluid flow across the interfaces between different types of inclusions (fractures, fluid patches) and background. Other models of intrinsic attenuation (in particular squirt flow models) cannot explain the amount of observed dispersion when using realistic rock properties. In order to interpret data in a satisfactory way we develop a superposition model for fractured porous rocks accounting also for the patchy saturation effect.
NASA Astrophysics Data System (ADS)
Gabovich, A. M.; Li, Mai Suan; Pekala, M.; Szymczak, H.; Voitenko, A. I.
2005-03-01
We consider tunnelling between a metal partially gapped by charge density waves (CDWM) and an ordinary metal (M) or a ferromagnet (FM) separated by an insulator (I) in an external magnetic field H. Zeeman paramagnetic splitting is assumed to dominate in the CDWM over orbital magnetic effects. The quasiparticle tunnel current J and relevant differential conductance G are calculated as functions of the bias voltage V. The peaks of G(V), originating from the electron density of states singularities near the charge density wave gap edges, were shown to be split in the magnetic field, each peak having a predominant spin polarization. This effect is analogous to the H-induced splitting of G(V) peaks obtained by Tedrow and Meservey for junctions between normal metals and superconductors (S). Thus, it is possible to electrically measure the polarization of current carriers in such a set-up, although the behaviours of G(V) in the two cases are substantially different. The use of M-I-CDWM junctions instead of M-I-S ones has certain advantages. The absence of the Meissner effect, which weakens the constraints upon the junction geometry and electrode materials, comprises the main benefit. The other advantage is the larger energy range of the charge density wave gaps in comparison to that for superconductors' gaps, so that larger Hs may be applied.
Bliokh, K Yu; Bliokh, Yu P
2007-06-01
We present a solution to the problem of partial reflection and refraction of a polarized paraxial Gaussian beam at the interface between two transparent media. The Fedorov-Imbert transverse shifts of the centers of gravity of the reflected and refracted beams are calculated. Our results differ in the general case from those derived previously by other authors. In particular, they obey general conservation law for the beams' total angular momentum but do not obey one-particle conservation laws for individual photons, which have been proposed by [Onoda Phys. Rev. Lett. 93, 083901 (2004)]. We ascertain that these circumstances relate to the artificial model accepted in the literature for the polarized beam; this model does not fit to real beams. The present paper resolves the recent controversy and confirms the results of our previous paper [Bliokh Phys. Rev. Lett. 96, 073903 (2006)]. In addition, a diffraction effect of angular transverse shifts of the reflected and refracted beams is described. PMID:17677378
Bliokh, K. Yu.; Bliokh, Yu. P.
2007-06-15
We present a solution to the problem of partial reflection and refraction of a polarized paraxial Gaussian beam at the interface between two transparent media. The Fedorov-Imbert transverse shifts of the centers of gravity of the reflected and refracted beams are calculated. Our results differ in the general case from those derived previously by other authors. In particular, they obey general conservation law for the beams' total angular momentum but do not obey one-particle conservation laws for individual photons, which have been proposed by [Onoda et al. Phys. Rev. Lett. 93, 083901 (2004)]. We ascertain that these circumstances relate to the artificial model accepted in the literature for the polarized beam; this model does not fit to real beams. The present paper resolves the recent controversy and confirms the results of our previous paper [Bliokh et al. Phys. Rev. Lett. 96, 073903 (2006)]. In addition, a diffraction effect of angular transverse shifts of the reflected and refracted beams is described.
Mode decomposition evolution equations
Wang, Yang; Wei, Guo-Wei; Yang, Siyang
2011-01-01
Partial differential equation (PDE) based methods have become some of the most powerful tools for exploring the fundamental problems in signal processing, image processing, computer vision, machine vision and artificial intelligence in the past two decades. The advantages of PDE based approaches are that they can be made fully automatic, robust for the analysis of images, videos and high dimensional data. A fundamental question is whether one can use PDEs to perform all the basic tasks in the image processing. If one can devise PDEs to perform full-scale mode decomposition for signals and images, the modes thus generated would be very useful for secondary processing to meet the needs in various types of signal and image processing. Despite of great progress in PDE based image analysis in the past two decades, the basic roles of PDEs in image/signal analysis are only limited to PDE based low-pass filters, and their applications to noise removal, edge detection, segmentation, etc. At present, it is not clear how to construct PDE based methods for full-scale mode decomposition. The above-mentioned limitation of most current PDE based image/signal processing methods is addressed in the proposed work, in which we introduce a family of mode decomposition evolution equations (MoDEEs) for a vast variety of applications. The MoDEEs are constructed as an extension of a PDE based high-pass filter (Europhys. Lett., 59(6): 814, 2002) by using arbitrarily high order PDE based low-pass filters introduced by Wei (IEEE Signal Process. Lett., 6(7): 165, 1999). The use of arbitrarily high order PDEs is essential to the frequency localization in the mode decomposition. Similar to the wavelet transform, the present MoDEEs have a controllable time-frequency localization and allow a perfect reconstruction of the original function. Therefore, the MoDEE operation is also called a PDE transform. However, modes generated from the present approach are in the spatial or time domain and can be
A complex Noether approach for variational partial differential equations
NASA Astrophysics Data System (ADS)
Naz, R.; Mahomed, F. M.
2015-10-01
Scalar complex partial differential equations which admit variational formulations are studied. Such a complex partial differential equation, via a complex dependent variable, splits into a system of two real partial differential equations. The decomposition of the Lagrangian of the complex partial differential equation in the real domain is shown to yield two real Lagrangians for the split system. The complex Maxwellian distribution, transonic gas flow, Maxwellian tails, dissipative wave and Klein-Gordon equations are considered. The Noether symmetries and gauge terms of the split system that correspond to both the Lagrangians are constructed by the Noether approach. In the case of coupled split systems, the same Noether symmetries are obtained. The Noether symmetries for the uncoupled split systems are different. The conserved vectors of the split system which correspond to both the Lagrangians are compared to the split conserved vectors of the complex partial differential equation for the examples. The split conserved vectors of the complex partial differential equation are the same as the conserved vectors of the split system of real partial differential equations in the case of coupled systems. Moreover a Noether-like theorem for the split system is proved which provides the Noether-like conserved quantities of the split system from knowledge of the Noether-like operators. An interesting result on the split characteristics and the conservation laws is shown as well. The Noether symmetries and gauge terms of the Lagrangian of the split system with the split Noether-like operators and gauge terms of the Lagrangian of the given complex partial differential equation are compared. Folklore suggests that the split Noether-like operators of a Lagrangian of a complex Euler-Lagrange partial differential equation are symmetries of the Lagrangian of the split system of real partial differential equations. This is not the case. They are proved to be the same if the
NASA Astrophysics Data System (ADS)
Valbuena, M. A.; Avila, J.; Pantin, V.; Drouard, S.; Guyot, H.; Asensio, M. C.
2006-05-01
Low dimensional (LD) metallic oxides have been a subject of continuous interest in the last two decades, mainly due to the electronic instabilities that they present at low temperatures. In particular, charge density waves (CDW) instabilities associated with a strong electron-phonon interaction have been found in Molybdenum metallic oxides such as KMo 6O 17 purple bronze. We report an angle resolved photoemission (ARPES) study from room temperature (RT) to T ˜40 K well below the Peierls transition temperature for this material, with CDW transition temperature TCDW ˜120 K. We have focused on photoemission spectra along ΓM high symmetry direction as well as photoemission measurements were taken as a function of temperature at one representative kF point in the Brillouin zone in order to look for the characteristic gap opening after the phase transition. We found out a pseudogap opening and a decrease in the density of states near the Fermi energy, EF, consistent with the partial removal of the nested portions of the Fermi surface (FS) at temperature below the CDW transition. In order to elucidate possible Fermi liquid (FL) or non-Fermi liquid (NFL) behaviour we have compared the ARPES data with that one reported on quasi-1D K 0.3MoO 3 blue bronze.
Partial wave analysis of the reaction p(3.5 GeV) + p → pK+ Λ to search for the "ppK–" bound state
Agakishiev, G.; Arnold, O.; Belver, D.; Belyaev, A.; Berger-Chen, J. C.; Blanco, A.; Böhmer, M.; Boyard, J. L.; Cabanelas, P.; Chernenko, S.; et al
2015-01-26
Employing the Bonn–Gatchina partial wave analysis framework (PWA), we have analyzed HADES data of the reaction p(3.5GeV) + p → pK+Λ. This reaction might contain information about the kaonic cluster “ppK-” (with quantum numbers JP=0- and total isospin I =1/2) via its decay into pΛ. Due to interference effects in our coherent description of the data, a hypothetical K ¯NN (or, specifically “ppK-”) cluster signal need not necessarily show up as a pronounced feature (e.g. a peak) in an invariant mass spectrum like pΛ. Our PWA analysis includes a variety of resonant and non-resonant intermediate states and delivers a goodmore » description of our data (various angular distributions and two-hadron invariant mass spectra) without a contribution of a K ¯NN cluster. At a confidence level of CLs=95% such a cluster cannot contribute more than 2–12% to the total cross section with a pK+ Λ final state, which translates into a production cross-section between 0.7 μb and 4.2 μb, respectively. The range of the upper limit depends on the assumed cluster mass, width and production process.« less
NASA Astrophysics Data System (ADS)
Andreev, Pavel A.; Iqbal, Z.
2016-03-01
We consider the separate spin evolution of electrons and positrons in electron-positron and electron-positron-ion plasmas. We consider the oblique propagating longitudinal waves in these systems. Working in a regime of high-density n0˜1027cm-3 and high-magnetic-field B0=1010 G, we report the presence of the spin-electron acoustic waves and their dispersion dependencies. In electron-positron plasmas, similarly to the electron-ion plasmas, we find one spin-electron acoustic wave (SEAW) at the propagation parallel or perpendicular to the external field and two spin-electron acoustic waves at the oblique propagation. At the parallel or perpendicular propagation of the longitudinal waves in electron-positron-ion plasmas, we find four branches: the Langmuir wave, the positron-acoustic wave, and a pair of waves having spin nature, they are the SEAW and the wave discovered in this paper, called the spin-electron-positron acoustic wave (SEPAW). At the oblique propagation we find eight longitudinal waves: the Langmuir wave, the Trivelpiece--Gould wave, a pair of positron-acoustic waves, a pair of SEAWs, and a pair of SEPAWs. Thus, for the first time, we report the existence of the second positron-acoustic wave existing at the oblique propagation and the existence of SEPAWs.
Thermal Decomposition Mechanism of Butyraldehyde
NASA Astrophysics Data System (ADS)
Hatten, Courtney D.; Warner, Brian; Wright, Emily; Kaskey, Kevin; McCunn, Laura R.
2013-06-01
The thermal decomposition of butyraldehyde, CH_3CH_2CH_2C(O)H, has been studied in a resistively heated SiC tubular reactor. Products of pyrolysis were identified via matrix-isolation FTIR spectroscopy and photoionization mass spectrometry in separate experiments. Carbon monoxide, ethene, acetylene, water and ethylketene were among the products detected. To unravel the mechanism of decomposition, pyrolysis of a partially deuterated sample of butyraldehyde was studied. Also, the concentration of butyraldehyde in the carrier gas was varied in experiments to determine the presence of bimolecular reactions. The results of these experiments can be compared to the dissociation pathways observed in similar aldehydes and are relevant to the processing of biomass, foods, and tobacco.
Scattering of an electromagnetic plane wave by a Luneburg lens. II. Wave theory.
Lock, James A
2008-12-01
The partial wave scattering and interior amplitudes for the interaction of an electromagnetic plane wave with a modified Luneburg lens are derived in terms of the exterior and interior radial functions of the scalar radiation potentials evaluated at the lens surface. A Debye series decomposition of these amplitudes is also performed and discussed. The effective potential inside the lens for the transverse electric polarization is qualitatively examined, and the approximate lens size parameters of morphology-dependent resonances are determined. Finally, the physical optics model is used to calculate wave scattering in the vicinity of the ray theory orbiting condition in order to demonstrate the smoothing of ray theory discontinuities by the diffraction of scattered waves. PMID:19037389
Integrated control/structure optimization by multilevel decomposition
NASA Technical Reports Server (NTRS)
Zeiler, Thomas A.; Gilbert, Michael G.
1990-01-01
A method for integrated control/structure optimization by multilevel decomposition is presented. It is shown that several previously reported methods were actually partial decompositions wherein only the control was decomposed into a subsystem design. One of these partially decomposed problems was selected as a benchmark example for comparison. The present paper fully decomposes the system into structural and control subsystem designs and produces an improved design. Theory, implementation, and results for the method are presented and compared with the benchmark example.
Integrated control/structure optimization by multilevel decomposition
NASA Technical Reports Server (NTRS)
Zeiler, Thomas A.; Gilbert, Michael G.
1990-01-01
A method for integrated control/structure optimization by multilevel decomposition is presented. It is shown that several previously reported methods were actually partial decompositions wherein only the control was decomposed into a subsystem design. One of these partially decomposed problems was selected as a benchmark example for comparison. The system is fully decomposed into structural and control subsystem designs and an improved design is produced. Theory, implementation, and results for the method are presented and compared with the benchmark example.
Nested Taylor decomposition in multivariate function decomposition
NASA Astrophysics Data System (ADS)
Baykara, N. A.; Gürvit, Ercan
2014-12-01
Fluctuationlessness approximation applied to the remainder term of a Taylor decomposition expressed in integral form is already used in many articles. Some forms of multi-point Taylor expansion also are considered in some articles. This work is somehow a combination these where the Taylor decomposition of a function is taken where the remainder is expressed in integral form. Then the integrand is decomposed to Taylor again, not necessarily around the same point as the first decomposition and a second remainder is obtained. After taking into consideration the necessary change of variables and converting the integration limits to the universal [0;1] interval a multiple integration system formed by a multivariate function is formed. Then it is intended to apply the Fluctuationlessness approximation to each of these integrals one by one and get better results as compared with the single node Taylor decomposition on which the Fluctuationlessness is applied.
Nonlinear mode decomposition: A noise-robust, adaptive decomposition method
NASA Astrophysics Data System (ADS)
Iatsenko, Dmytro; McClintock, Peter V. E.; Stefanovska, Aneta
2015-09-01
The signals emanating from complex systems are usually composed of a mixture of different oscillations which, for a reliable analysis, should be separated from each other and from the inevitable background of noise. Here we introduce an adaptive decomposition tool—nonlinear mode decomposition (NMD)—which decomposes a given signal into a set of physically meaningful oscillations for any wave form, simultaneously removing the noise. NMD is based on the powerful combination of time-frequency analysis techniques—which, together with the adaptive choice of their parameters, make it extremely noise robust—and surrogate data tests used to identify interdependent oscillations and to distinguish deterministic from random activity. We illustrate the application of NMD to both simulated and real signals and demonstrate its qualitative and quantitative superiority over other approaches, such as (ensemble) empirical mode decomposition, Karhunen-Loève expansion, and independent component analysis. We point out that NMD is likely to be applicable and useful in many different areas of research, such as geophysics, finance, and the life sciences. The necessary matlab codes for running NMD are freely available for download.
Nonlinear mode decomposition: a noise-robust, adaptive decomposition method.
Iatsenko, Dmytro; McClintock, Peter V E; Stefanovska, Aneta
2015-09-01
The signals emanating from complex systems are usually composed of a mixture of different oscillations which, for a reliable analysis, should be separated from each other and from the inevitable background of noise. Here we introduce an adaptive decomposition tool-nonlinear mode decomposition (NMD)-which decomposes a given signal into a set of physically meaningful oscillations for any wave form, simultaneously removing the noise. NMD is based on the powerful combination of time-frequency analysis techniques-which, together with the adaptive choice of their parameters, make it extremely noise robust-and surrogate data tests used to identify interdependent oscillations and to distinguish deterministic from random activity. We illustrate the application of NMD to both simulated and real signals and demonstrate its qualitative and quantitative superiority over other approaches, such as (ensemble) empirical mode decomposition, Karhunen-Loève expansion, and independent component analysis. We point out that NMD is likely to be applicable and useful in many different areas of research, such as geophysics, finance, and the life sciences. The necessary matlab codes for running NMD are freely available for download. PMID:26465549
NASA Astrophysics Data System (ADS)
Ye, Sheng-ying; Zheng, Sen-hong; Song, Xian-liang; Luo, Shu-can
2015-06-01
Removing ethylene (C2H4) from the atmosphere of storage facilities for fruits and vegetable is one of the main challenges in their postharvest handling for maximizing their freshness, quality, and shelf life. In this study, we investigated the photoelectrocatalytic (PEC) degradation of ethylene gas by applying a pulsed direct current DC square-wave (PDCSW) potential and by using a Nafion-based PEC cell. The cell utilized a titanium dioxide (TiO2) photocatalyst or γ-irradiated TiO2 (TiO2*) loaded on activated carbon fiber (ACF) as a photoelectrode. The apparent rate constant of a pseudo-first-order reaction (K) was used to describe the PEC degradation of ethylene. Parameters of the potential applied to the PEC cell in a reactor that affect the degradation efficiency in terms of the K value were studied. These parameters were frequency, duty cycle, and voltage. Ethylene degradation by application of a constant PDCSW potential to the PEC electrode of either TiO2/ACF cell or TiO2*/ACF cell enhanced the efficiency of photocatalytic degradation and PEC degradation. Gamma irradiation of TiO2 in the electrode and the applied PDCSW potential synergistically increased the K value. Independent variables (frequency, duty cycle, and voltage) of the PEC cell fabricated from TiO2 subjected 20 kGy γ radiation were optimized to maximize the K value by using response surface methodology with quadratic rotation-orthogonal composite experimental design. Optimized conditions were as follows: 358.36 Hz frequency, 55.79% duty cycle, and 64.65 V voltage. The maximum K value attained was 4.4 × 10-4 min-1.
Circulant states with positive partial transpose
Chruscinski, Dariusz; Kossakowski, Andrzej
2007-09-15
We construct a large class of quantum dxd states which are positive under partial transposition (so called PPT states). The construction is based on certain direct sum decomposition of the total Hilbert space displaying characteristic circular structure - that is why we call them circulant states. It turns out that partial transposition maps any such decomposition into another one and hence both original density matrix and its partially transposed partner share similar cyclic properties. This class contains many well-known examples of PPT states from the literature and gives rise to a huge family of completely new states.
Type-Decomposition of an Effect Algebra
NASA Astrophysics Data System (ADS)
Foulis, David J.; Pulmannová, Sylvia
2010-10-01
Effect algebras (EAs), play a significant role in quantum logic, are featured in the theory of partially ordered Abelian groups, and generalize orthoalgebras, MV-algebras, orthomodular posets, orthomodular lattices, modular ortholattices, and boolean algebras. We study centrally orthocomplete effect algebras (COEAs), i.e., EAs satisfying the condition that every family of elements that is dominated by an orthogonal family of central elements has a supremum. For COEAs, we introduce a general notion of decomposition into types; prove that a COEA factors uniquely as a direct sum of types I, II, and III; and obtain a generalization for COEAs of Ramsay’s fourfold decomposition of a complete orthomodular lattice.
NASA Astrophysics Data System (ADS)
Kozhevnikov, V. A.; Sherman, S. G.
2008-11-01
The partial-wave inelasticity parameters of the amplitude for elastic pion-nucleon scattering are determined with the aid of the phenomenological amplitude for inelastic π N → ππ N processes in the energy range extending to the threshold for the production of two pions. The resulting inelasticity parameters are compared with their counterparts derived from modern partial-wave analyses. The largest inelastic-scattering cross section in the P11 wave is in excellent agreement with the analogous value from the analysis performed at the George Washington University in 2006. For other waves, however, the present results differ in the majority of cases from respective values given by partial-wave analyses (the distinctions are especially large for the isospin-3/2 amplitudes).
Limits to acoustic sensing and modal decomposition using FBGs
NASA Astrophysics Data System (ADS)
Norman, Patrick; Davis, Claire; Rosalie, Cédric; Rajic, Nik
2016-04-01
Lamb-wave based structural health monitoring (SHM) approaches are typically constrained to operate below the first cut-off frequency to simplify the interpretation of the wave field in the time-domain. However from a diagnostic perspective, it is desirable to unlock the additional information encoded in the higher-order Lamb wave spectrum. Wave-mode decomposition is necessary for the extraction of useful information from multi-modal acoustic wave fields, which requires spatially dense sampling over the field. The instrument of choice for this task is the laser Doppler vibrometer, which is capable of producing detailed spectral decompositions. However vibrometry is not suited to in-situ measurement for SHM. Fibre Bragg gratings (FBGs) are capable of sensing Lamb waves and detection of higher order modes using FBGs has been previously demonstrated. The ability to multiplex multiple short-length gratings along a single fibre to create an FBG array gives rise to an in-situ sensor with sufficiently dense spatial sampling of an acoustic wave field to perform useful wave-mode decomposition. This paper explores some of the fundamental limits to modal decomposition resolution and bandwidth that exist for such sensors. Potential sources of noise and distortion encountered due to limitations of the sensor fabrication and interrogation methods are also discussed. In addition, modal decomposition of Lamb waves with frequencies up to 1.25 MHz is demonstrated in a laboratory experiment using an array of sixteen ~1 mm long gratings bonded to an aluminium plate. At least four modes are distinguishable in the resulting spectral decomposition.
Orthogonal tensor decompositions
Tamara G. Kolda
2000-03-01
The authors explore the orthogonal decomposition of tensors (also known as multi-dimensional arrays or n-way arrays) using two different definitions of orthogonality. They present numerous examples to illustrate the difficulties in understanding such decompositions. They conclude with a counterexample to a tensor extension of the Eckart-Young SVD approximation theorem by Leibovici and Sabatier [Linear Algebra Appl. 269(1998):307--329].
Dzierba, A.R.; Mitchell, R.; Scott, E.; Shepherd, M.R.; Smith, P.; Swat, M.; Teige, S.; Szczepaniak, A.P.; Denisov, S.P.; Dorofeev, V.; Kachaev, I.; Lipaev, V.; Popov, A.V.; Ryabchikov, D.I.; Bodyagin, V.A.; Demianov, A.
2006-04-01
A partial wave analysis (PWA) of the {pi}{sup -}{pi}{sup -}{pi}{sup +} and {pi}{sup -}{pi}{sup 0}{pi}{sup 0} systems produced in the reaction {pi}{sup -}p{yields}(3{pi}){sup -}p at 18 GeV/c was carried out using an isobar model assumption. This analysis is based on 3.0 M {pi}{sup -}{pi}{sup 0}{pi}{sup 0} events and 2.6 M {pi}{sup -}{pi}{sup -}{pi}{sup +} events and shows production of the a{sub 1}(1260), a{sub 2}(1320), {pi}{sub 2}(1670), and a{sub 4}(2040) resonances. Results of detailed studies of the stability of partial wave fits are presented. An earlier analysis of 250 K {pi}{sup -}{pi}{sup -}{pi}{sup +} events from the same experiment showed possible evidence for a J{sup PC}=1{sup -+} exotic meson with a mass of {approx}1.6 GeV/c{sup 2} decaying into {rho}{pi}. In this analysis of a higher statistics sample of the (3{pi}){sup -} system in two charged modes we find no evidence of an exotic meson.
NASA Astrophysics Data System (ADS)
Oberhardt, Tobias; Kim, Jin-Yeon; Qu, Jianmin; Jacobs, Laurence J.
2016-02-01
This research investigates the modeling of randomly distributed surface-breaking microcracks and the dependency of higher harmonic generation in Rayleigh surface waves on microcrack density. The microcrack model is based on micromechanical considerations of rough surface contact. An effective stress-strain relationship is derived to describe the nonlinear behavior of a single microcrack and implemented into a finite-element model via a hyperelastic constitutive law. Finite-element simulations of nonlinear wave propagation in a solid with distributed surface microcracks are performed for a range of microcrack densities. The evolution of fundamental and second harmonic amplitudes along the propagation distance is studied and the acoustic nonlinearity parameter is calculated. The results show that the nonlinearity parameter increases with crack density. While, for small crack densities (dilute concentration of microcracks) a proportionality between crack density and acoustic nonlinearity is observed, this is not valid for higher crack densities, as the microcracks start to interact.
NASA Astrophysics Data System (ADS)
Rudnick, Roberta L.; Jackson, Ian
1995-06-01
Ultrasonic compressional wave velocities measured at 1.0 GPa and room temperature are compared with calculated velocities (based on single-crystal data and modal mineralogy) for a suite of mafic granulite xenoliths from the Chudleigh volcanic province, north Queensland, Australia. The xenoliths have nearly constant major element compositions but widely variable modal mineralogy, reflecting recrystallization under variable pressure-temperature conditions at depth in the continental crust (20-45 km). They thus provide an excellent opportunity to investigate velocity variation with depth in a mafic lower crust. Measured P wave velocities, corrected for the decompression-induced breakdown of garnet, range from 6.9 to 7.6 km/sec and correlate with derivation depth. These velocities are 5-12% lower than the calculated velocities (7.5-8.0 km/sec), apparently as a result of grain boundary alteration as well as irreversible changes that occurred in the xenoliths during rapid decompression. Calculated P wave velocities are similar to those estimated by Furlong and Fountain (1986) and Sobolev and Babeyko (1989) for mafic granulites formed through basaltic underplating of the continental crust. Depending upon in situ temperature, P wave velocities in the deepest samples may be interpreted as crustal (e.g., 7.3-7.6 km/sec, if heat flow is high) or mantle (7.7-7.8 km/sec, in areas of low heat flow). The range of velocities in the xenolith suite is larger than predicted for a fully equilibrated underplated basaltic layer, highlighting the importance of kinetic effects in determining the ultimate velocity profile of magmatically underplated crust. Comparison of our results with seismic profiles illustrates that the lower crust rarely reaches such high velocities, suggesting quartz-bearing rocks (country rocks?) are present within magmatically underplated layers of the deep crust.
Decomposition Products of RDX and TNT after Resonant Laser Excitation
NASA Astrophysics Data System (ADS)
Monat, Jeremy; Gump, Jared
2009-06-01
This presentation describes research on the gas-phase products of decomposition of explosives after resonant laser excitation. We studied RDX, TNT, and formulations containing them after excitation by lasers in the infrared (10.6 4μm continuous-wave [CW]; resonant with ring vibrational modes) and ultraviolet (266 nm CW and pulsed [ca. 5 ns pulsewidth]; resonant with delocalized ring electronic absorptions). The decomposition products in air were identified by infrared spectroscopy and will be described as a function of laser wavelength and energy deposition timescale. Our results will be compared to decomposition pathways in the literature derived from resistive heating techniques.
Decomposition products of TATB under high static pressure
NASA Astrophysics Data System (ADS)
Crowhurst, Jonathan; Stavrou, Elissaios; Zaug, Joseph
We have investigated the decomposition products of 2,4,6-triamino-1,3,5-trinitrobenzene (TATB) at static pressures up to 50 GPa using Raman and IR absorption spectroscopy. Decomposition was driven by various continuous wave and pulsed laser drives. We compare decomposition behavior and products obtained at the different pressures. Preliminary results at lower pressures indicate the formation of carbon dioxide, nitrogen, amorphous carbon and possibly hydrogen. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344
Decomposing Nekrasov decomposition
NASA Astrophysics Data System (ADS)
Morozov, A.; Zenkevich, Y.
2016-02-01
AGT relations imply that the four-point conformal block admits a decomposition into a sum over pairs of Young diagrams of essentially rational Nekrasov functions — this is immediately seen when conformal block is represented in the form of a matrix model. However, the q-deformation of the same block has a deeper decomposition — into a sum over a quadruple of Young diagrams of a product of four topological vertices. We analyze the interplay between these two decompositions, their properties and their generalization to multi-point conformal blocks. In the latter case we explain how Dotsenko-Fateev all-with-all (star) pair "interaction" is reduced to the quiver model nearest-neighbor (chain) one. We give new identities for q-Selberg averages of pairs of generalized Macdonald polynomials. We also translate the slicing invariance of refined topological strings into the language of conformal blocks and interpret it as abelianization of generalized Macdonald polynomials.
Kao, Jim . E-mail: kao@lanl.gov; Flicker, Dawn; Ide, Kayo; Ghil, Michael
2006-05-20
This paper builds upon our recent data assimilation work with the extended Kalman filter (EKF) method [J. Kao, D. Flicker, R. Henninger, S. Frey, M. Ghil, K. Ide, Data assimilation with an extended Kalman filter for an impact-produced shock-wave study, J. Comp. Phys. 196 (2004) 705-723.]. The purpose is to test the capability of EKF in optimizing a model's physical parameters. The problem is to simulate the evolution of a shock produced through a high-speed flyer plate. In the earlier work, we have showed that the EKF allows one to estimate the evolving state of the shock wave from a single pressure measurement, assuming that all model parameters are known. In the present paper, we show that imperfectly known model parameters can also be estimated accordingly, along with the evolving model state, from the same single measurement. The model parameter optimization using the EKF can be achieved through a simple modification of the original EKF formalism by including the model parameters into an augmented state variable vector. While the regular state variables are governed by both deterministic and stochastic forcing mechanisms, the parameters are only subject to the latter. The optimally estimated model parameters are thus obtained through a unified assimilation operation. We show that improving the accuracy of the model parameters also improves the state estimate. The time variation of the optimized model parameters results from blending the data and the corresponding values generated from the model and lies within a small range, of less than 2%, from the parameter values of the original model. The solution computed with the optimized parameters performs considerably better and has a smaller total variance than its counterpart using the original time-constant parameters. These results indicate that the model parameters play a dominant role in the performance of the shock-wave hydrodynamic code at hand.
Oxley, J.C.; Smith, J.L.; Yeager, K.E.; Rogers, E.; Dong, X.X.
1996-07-01
To examine the thermal decomposition of 5-nitro-2,4-dihydro-3H-1,2,4-triazol-3-one (NTO) in detail, isotopic labeling studies were undertaken. NTO samples labeled with {sup 15}N in three different locations [N(1) and N(2), N(4), and N(6)] were prepared. Upon thermolysis, the majority of the NTO condensed-phase product was a brown, insoluble residue, but small quantities of 2,4-dihydro-3H-1,2,4-triazol-3-one (TO) and triazole were detected. Gases comprised the remainder of the NTO decomposition products. The analysis of these gases is reported along with mechanistic implications of these observations.
Rao, V.S.; Skinner, G.B. )
1989-03-09
Very dilute mixtures of CD{sub 2}CHCH{sub 3}, CH{sub 2}CDCH{sub 3}, and CH{sub 2}CHCD{sub 3} were pyrolyzed at 1500-1800 K behind incident shock waves at an average pressure of 0.42 atm and behind reflected waves at 2.8 atm. Analysis for H and D using resonance absorption spectroscopy showed that propene dissociates partly by formation of hydrogen atoms and allyl radicals, (1), and partly by formation of vinyl and methyl radicals, (2). Both of these unimolecular dissociation reactions of propene are in the intermediate falloff region at our pressures and temperatures. For (1) we find k{sub 1} = 3.5 {times} 10{sup 12} exp(-75 kcal/RT) s{sup {minus}1} at 0.42 atm and k{sub 1} = 3.6 {times} 10{sup 13} exp(-80 kcal/RT) s{sup {minus}1} at 2.8 atm. For (2) we find k{sub 2} = 8.2 {times} 10{sup 12} exp(-80 kcal/RT) s{sup {minus}1} at 0.42 atm and k{sub 2} = 2.3 {times} 10{sup 13} exp(-80 kcal/RT) s{sup {minus}1} at 2.8 atm. Estimated uncertainties are factors of 1.5 in (1) and 2 in (2).
2011-01-01
Introduction About 3% of people will be diagnosed with epilepsy during their lifetime, but about 70% of people with epilepsy eventually go into remission. Methods and outcomes We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of starting antiepileptic drug treatment following a single seizure? What are the effects of drug monotherapy in people with partial epilepsy? What are the effects of additional drug treatments in people with drug-resistant partial epilepsy? What is the risk of relapse in people in remission when withdrawing antiepileptic drugs? What are the effects of behavioural and psychological treatments for people with epilepsy? What are the effects of surgery in people with drug-resistant temporal lobe epilepsy? We searched: Medline, Embase, The Cochrane Library, and other important databases up to July 2009 (Clinical Evidence reviews are updated periodically; please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA). Results We found 83 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions. Conclusions In this systematic review we present information relating to the effectiveness and safety of the following interventions: antiepileptic drugs after a single seizure; monotherapy for partial epilepsy using carbamazepine, gabapentin, lamotrigine, levetiracetam, phenobarbital, phenytoin, sodium valproate, or topiramate; addition of second-line drugs for drug-resistant partial epilepsy (allopurinol, eslicarbazepine, gabapentin, lacosamide, lamotrigine, levetiracetam, losigamone, oxcarbazepine, retigabine, tiagabine, topiramate, vigabatrin, or zonisamide); antiepileptic drug withdrawal for people with partial or
An Alternative Method to the Classical Partial Fraction Decomposition
ERIC Educational Resources Information Center
Cherif, Chokri
2007-01-01
PreCalculus students can use the Completing the Square Method to solve quadratic equations without the need to memorize the quadratic formula since this method naturally leads them to that formula. Calculus students, when studying integration, use various standard methods to compute integrals depending on the type of function to be integrated.…
Hydrazine decomposition and other reactions
NASA Technical Reports Server (NTRS)
Armstrong, Warren E. (Inventor); La France, Donald S. (Inventor); Voge, Hervey H. (Inventor)
1978-01-01
This invention relates to the catalytic decomposition of hydrazine, catalysts useful for this decomposition and other reactions, and to reactions in hydrogen atmospheres generally using carbon-containing catalysts.
Odd and even partial waves of ηπ- and η‧π- in π- p →η (‧)π- p at 191 GeV / c
NASA Astrophysics Data System (ADS)
Adolph, C.; Akhunzyanov, R.; Alexeev, M. G.; Alexeev, G. D.; Amoroso, A.; Andrieux, V.; Anosov, V.; Austregesilo, A.; Badełek, B.; Balestra, F.; Barth, J.; Baum, G.; Beck, R.; Bedfer, Y.; Berlin, A.; Bernhard, J.; Bicker, K.; Bielert, E. R.; Bieling, J.; Birsa, R.; Bisplinghoff, J.; Bodlak, M.; Boer, M.; Bordalo, P.; Bradamante, F.; Braun, C.; Bressan, A.; Büchele, M.; Burtin, E.; Capozza, L.; Chiosso, M.; Chung, S. U.; Cicuttin, A.; Crespo, M. L.; Curiel, Q.; Dalla Torre, S.; Dasgupta, S. S.; Dasgupta, S.; Denisov, O. Yu.; Donskov, S. V.; Doshita, N.; Duic, V.; Dünnweber, W.; Dziewiecki, M.; Efremov, A.; Elia, C.; Eversheim, P. D.; Eyrich, W.; Faessler, M.; Ferrero, A.; Finger, M.; Finger, M.; Fischer, H.; Franco, C.; du Fresne von Hohenesche, N.; Friedrich, J. M.; Frolov, V.; Gautheron, F.; Gavrichtchouk, O. P.; Gerassimov, S.; Geyer, R.; Gnesi, I.; Gobbo, B.; Goertz, S.; Gorzellik, M.; Grabmüller, S.; Grasso, A.; Grube, B.; Grussenmeyer, T.; Guskov, A.; Haas, F.; von Harrach, D.; Hahne, D.; Hashimoto, R.; Heinsius, F. H.; Herrmann, F.; Hinterberger, F.; Höppner, Ch.; Horikawa, N.; d'Hose, N.; Huber, S.; Ishimoto, S.; Ivanov, A.; Ivanshin, Yu.; Iwata, T.; Jahn, R.; Jary, V.; Jasinski, P.; Jörg, P.; Joosten, R.; Kabuß, E.; Ketzer, B.; Khaustov, G. V.; Khokhlov, Yu. A.; Kisselev, Yu.; Klein, F.; Klimaszewski, K.; Koivuniemi, J. H.; Kolosov, V. N.; Kondo, K.; Königsmann, K.; Konorov, I.; Konstantinov, V. F.; Kotzinian, A. M.; Kouznetsov, O.; Krämer, M.; Kroumchtein, Z. V.; Kuchinski, N.; Kunne, F.; Kurek, K.; Kurjata, R. P.; Lednev, A. A.; Lehmann, A.; Levillain, M.; Levorato, S.; Lichtenstadt, J.; Maggiora, A.; Magnon, A.; Makke, N.; Mallot, G. K.; Marchand, C.; Martin, A.; Marzec, J.; Matousek, J.; Matsuda, H.; Matsuda, T.; Meshcheryakov, G.; Meyer, W.; Michigami, T.; Mikhailov, Yu. V.; Miyachi, Y.; Nagaytsev, A.; Nagel, T.; Nerling, F.; Neubert, S.; Neyret, D.; Novy, J.; Nowak, W.-D.; Nunes, A. S.; Olshevsky, A. G.; Orlov, I.; Ostrick, M.; Panknin, R.; Panzieri, D.; Parsamyan, B.; Paul, S.; Peshekhonov, D. V.; Platchkov, S.; Pochodzalla, J.; Polyakov, V. A.; Pretz, J.; Quaresma, M.; Quintans, C.; Ramos, S.; Regali, C.; Reicherz, G.; Rocco, E.; Rossiyskaya, N. S.; Ryabchikov, D. I.; Rychter, A.; Samoylenko, V. D.; Sandacz, A.; Sarkar, S.; Savin, I. A.; Sbrizzai, G.; Schiavon, P.; Schill, C.; Schlüter, T.; Schmidt, K.; Schmieden, H.; Schönning, K.; Schopferer, S.; Schott, M.; Shevchenko, O. Yu.; Silva, L.; Sinha, L.; Sirtl, S.; Slunecka, M.; Sosio, S.; Sozzi, F.; Srnka, A.; Steiger, L.; Stolarski, M.; Sulc, M.; Sulej, R.; Suzuki, H.; Szabelski, A.; Szameitat, T.; Sznajder, P.; Takekawa, S.; ter Wolbeek, J.; Tessaro, S.; Tessarotto, F.; Thibaud, F.; Uhl, S.; Uman, I.; Virius, M.; Wang, L.; Weisrock, T.; Wilfert, M.; Windmolders, R.; Wollny, H.; Zaremba, K.; Zavertyaev, M.; Zemlyanichkina, E.; Ziembicki, M.; Zink, A.
2015-01-01
Exclusive production of ηπ- and η‧π- has been studied with a 191 GeV / cπ- beam impinging on a hydrogen target at COMPASS (CERN). Partial-wave analyses reveal different odd/even angular momentum (L) characteristics in the inspected invariant mass range up to 3 GeV /c2. A striking similarity between the two systems is observed for the L = 2 , 4 , 6 intensities (scaled by kinematical factors) and the relative phases. The known resonances a2 (1320) and a4 (2040) are in line with this similarity. In contrast, a strong enhancement of η‧π- over ηπ- is found for the L = 1 , 3 , 5 waves, which carry non- q q bar quantum numbers. The L = 1 intensity peaks at 1.7 GeV /c2 in η‧π- and at 1.4 GeV /c2 in ηπ-, the corresponding phase motions with respect to L = 2 are different.
Domain decomposition: A bridge between nature and parallel computers
NASA Technical Reports Server (NTRS)
Keyes, David E.
1992-01-01
Domain decomposition is an intuitive organizing principle for a partial differential equation (PDE) computation, both physically and architecturally. However, its significance extends beyond the readily apparent issues of geometry and discretization, on one hand, and of modular software and distributed hardware, on the other. Engineering and computer science aspects are bridged by an old but recently enriched mathematical theory that offers the subject not only unity, but also tools for analysis and generalization. Domain decomposition induces function-space and operator decompositions with valuable properties. Function-space bases and operator splittings that are not derived from domain decompositions generally lack one or more of these properties. The evolution of domain decomposition methods for elliptically dominated problems has linked two major algorithmic developments of the last 15 years: multilevel and Krylov methods. Domain decomposition methods may be considered descendants of both classes with an inheritance from each: they are nearly optimal and at the same time efficiently parallelizable. Many computationally driven application areas are ripe for these developments. A progression is made from a mathematically informal motivation for domain decomposition methods to a specific focus on fluid dynamics applications. To be introductory rather than comprehensive, simple examples are provided while convergence proofs and algorithmic details are left to the original references; however, an attempt is made to convey their most salient features, especially where this leads to algorithmic insight.
Multicriteria approximation through decomposition
Burch, C. |; Krumke, S.; Marathe, M.; Phillips, C.; Sundberg, E. |
1997-12-01
The authors propose a general technique called solution decomposition to devise approximation algorithms with provable performance guarantees. The technique is applicable to a large class of combinatorial optimization problems that can be formulated as integer linear programs. Two key ingredients of the technique involve finding a decomposition of a fractional solution into a convex combination of feasible integral solutions and devising generic approximation algorithms based on calls to such decompositions as oracles. The technique is closely related to randomized rounding. The method yields as corollaries unified solutions to a number of well studied problems and it provides the first approximation algorithms with provable guarantees for a number of new problems. The particular results obtained in this paper include the following: (1) The authors demonstrate how the technique can be used to provide more understanding of previous results and new algorithms for classical problems such as Multicriteria Spanning Trees, and Suitcase Packing. (2) They show how the ideas can be extended to apply to multicriteria optimization problems, in which they wish to minimize a certain objective function subject to one or more budget constraints. As corollaries they obtain first non-trivial multicriteria approximation algorithms for problems including the k-Hurdle and the Network Inhibition problems.
Multicriteria approximation through decomposition
Burch, C.; Krumke, S.; Marathe, M.; Phillips, C.; Sundberg, E.
1998-06-01
The authors propose a general technique called solution decomposition to devise approximation algorithms with provable performance guarantees. The technique is applicable to a large class of combinatorial optimization problems that can be formulated as integer linear programs. Two key ingredients of their technique involve finding a decomposition of a fractional solution into a convex combination of feasible integral solutions and devising generic approximation algorithms based on calls to such decompositions as oracles. The technique is closely related to randomized rounding. Their method yields as corollaries unified solutions to a number of well studied problems and it provides the first approximation algorithms with provable guarantees for a number of new problems. The particular results obtained in this paper include the following: (1) the authors demonstrate how the technique can be used to provide more understanding of previous results and new algorithms for classical problems such as Multicriteria Spanning Trees, and Suitcase Packing; (2) they also show how the ideas can be extended to apply to multicriteria optimization problems, in which they wish to minimize a certain objective function subject to one or more budget constraints. As corollaries they obtain first non-trivial multicriteria approximation algorithms for problems including the k-Hurdle and the Network Inhibition problems.
NASA Astrophysics Data System (ADS)
Saleeby, J.; Le Pourhiet, L.
2012-12-01
runs is a chain of events that initiates with the basal thermal perturbation and load of the arclogite root inducing Rayleigh-Taylor (RT) instability within the peridotitic lithosphere, as well as the development of a lower crustal channel along the eastern margin of root, which draws lower crust into the eastern Sierra region from the adjacent Basin and Range. These lead to a lithospheric break-off event that corresponds to the ca. 10 Ma inception of the Sierra Nevada microplate, and which further promotes the east to west delamination of the arclogite root. Initial topography is shown to influence the asymmetry of delamination. Much of our model experimentation consists of testing the influence of crustal rheology on model results. We find that a relatively weak crust for the entire microplate best reproduces rock uplift and tectonic subsidence observations, as well as the timing and source characteristics of observed volcanism. We apply the findings of our 2-D models to 3-D relationships across the southern Sierra region in order to elucidate the time transgressive patterns in uplift, subsidence, volcanism and shallow thermal anomalies in relation to the 3-D delamination of the root, and the production of the higher Vp core of the anomaly. These relations suggest a significant compositional component to the core area of the anomaly (deformed arclogite slab), while the peridotitic envelope produces a broad thermally-induced wave-speed anomaly.
Fulvenallene decomposition kinetics.
Polino, Daniela; Cavallotti, Carlo
2011-09-22
While the decomposition kinetics of the benzyl radical has been studied in depth both from the experimental and the theoretical standpoint, much less is known about the reactivity of what is likely to be its main decomposition product, fulvenallene. In this work the high temperature reactivity of fulvenallene was investigated on a Potential Energy Surface (PES) consisting of 10 wells interconnected through 11 transition states using a 1 D Master Equation (ME). Rate constants were calculated using RRKM theory and the ME was integrated using a stochastic kinetic Monte Carlo code. It was found that two main decomposition channels are possible, the first is active on the singlet PES and leads to the formation of the fulvenallenyl radical and atomic hydrogen. The second requires intersystem crossing to the triplet PES and leads to acetylene and cyclopentadienylidene. ME simulations were performed calculating the microcanonical intersystem crossing frequency using Landau-Zener theory convoluting the crossing probability with RRKM rates evaluated at the conical intersection. It was found that the reaction channel leading to the cyclopentadienylidene diradical is only slightly faster than that leading to the fulvenallenyl radical, so that it can be concluded that both reactions are likely to be active in the investigated temperature (1500-2000 K) and pressure (0.05-50 bar) ranges. However, the simulations show that intersystem crossing is rate limiting for the first reaction channel, as the removal of this barrier leads to an increase of the rate constant by a factor of 2-3. Channel specific rate constants are reported as a function of temperature and pressure. PMID:21819060
Hydrogen peroxide catalytic decomposition
NASA Technical Reports Server (NTRS)
Parrish, Clyde F. (Inventor)
2010-01-01
Nitric oxide in a gaseous stream is converted to nitrogen dioxide using oxidizing species generated through the use of concentrated hydrogen peroxide fed as a monopropellant into a catalyzed thruster assembly. The hydrogen peroxide is preferably stored at stable concentration levels, i.e., approximately 50%-70% by volume, and may be increased in concentration in a continuous process preceding decomposition in the thruster assembly. The exhaust of the thruster assembly, rich in hydroxyl and/or hydroperoxy radicals, may be fed into a stream containing oxidizable components, such as nitric oxide, to facilitate their oxidation.
Tensor decomposition of EEG signals: a brief review.
Cong, Fengyu; Lin, Qiu-Hua; Kuang, Li-Dan; Gong, Xiao-Feng; Astikainen, Piia; Ristaniemi, Tapani
2015-06-15
Electroencephalography (EEG) is one fundamental tool for functional brain imaging. EEG signals tend to be represented by a vector or a matrix to facilitate data processing and analysis with generally understood methodologies like time-series analysis, spectral analysis and matrix decomposition. Indeed, EEG signals are often naturally born with more than two modes of time and space, and they can be denoted by a multi-way array called as tensor. This review summarizes the current progress of tensor decomposition of EEG signals with three aspects. The first is about the existing modes and tensors of EEG signals. Second, two fundamental tensor decomposition models, canonical polyadic decomposition (CPD, it is also called parallel factor analysis-PARAFAC) and Tucker decomposition, are introduced and compared. Moreover, the applications of the two models for EEG signals are addressed. Particularly, the determination of the number of components for each mode is discussed. Finally, the N-way partial least square and higher-order partial least square are described for a potential trend to process and analyze brain signals of two modalities simultaneously. PMID:25840362
Vertebrate decomposition is accelerated by soil microbes.
Lauber, Christian L; Metcalf, Jessica L; Keepers, Kyle; Ackermann, Gail; Carter, David O; Knight, Rob
2014-08-01
Carrion decomposition is an ecologically important natural phenomenon influenced by a complex set of factors, including temperature, moisture, and the activity of microorganisms, invertebrates, and scavengers. The role of soil microbes as decomposers in this process is essential but not well understood and represents a knowledge gap in carrion ecology. To better define the role and sources of microbes in carrion decomposition, lab-reared mice were decomposed on either (i) soil with an intact microbial community or (ii) soil that was sterilized. We characterized the microbial community (16S rRNA gene for bacteria and archaea, and the 18S rRNA gene for fungi and microbial eukaryotes) for three body sites along with the underlying soil (i.e., gravesoils) at time intervals coinciding with visible changes in carrion morphology. Our results indicate that mice placed on soil with intact microbial communities reach advanced stages of decomposition 2 to 3 times faster than those placed on sterile soil. Microbial communities associated with skin and gravesoils of carrion in stages of active and advanced decay were significantly different between soil types (sterile versus untreated), suggesting that substrates on which carrion decompose may partially determine the microbial decomposer community. However, the source of the decomposer community (soil- versus carcass-associated microbes) was not clear in our data set, suggesting that greater sequencing depth needs to be employed to identify the origin of the decomposer communities in carrion decomposition. Overall, our data show that soil microbial communities have a significant impact on the rate at which carrion decomposes and have important implications for understanding carrion ecology. PMID:24907317
Vertebrate Decomposition Is Accelerated by Soil Microbes
Lauber, Christian L.; Metcalf, Jessica L.; Keepers, Kyle; Ackermann, Gail; Carter, David O.
2014-01-01
Carrion decomposition is an ecologically important natural phenomenon influenced by a complex set of factors, including temperature, moisture, and the activity of microorganisms, invertebrates, and scavengers. The role of soil microbes as decomposers in this process is essential but not well understood and represents a knowledge gap in carrion ecology. To better define the role and sources of microbes in carrion decomposition, lab-reared mice were decomposed on either (i) soil with an intact microbial community or (ii) soil that was sterilized. We characterized the microbial community (16S rRNA gene for bacteria and archaea, and the 18S rRNA gene for fungi and microbial eukaryotes) for three body sites along with the underlying soil (i.e., gravesoils) at time intervals coinciding with visible changes in carrion morphology. Our results indicate that mice placed on soil with intact microbial communities reach advanced stages of decomposition 2 to 3 times faster than those placed on sterile soil. Microbial communities associated with skin and gravesoils of carrion in stages of active and advanced decay were significantly different between soil types (sterile versus untreated), suggesting that substrates on which carrion decompose may partially determine the microbial decomposer community. However, the source of the decomposer community (soil- versus carcass-associated microbes) was not clear in our data set, suggesting that greater sequencing depth needs to be employed to identify the origin of the decomposer communities in carrion decomposition. Overall, our data show that soil microbial communities have a significant impact on the rate at which carrion decomposes and have important implications for understanding carrion ecology. PMID:24907317
O'Keefe, Dennis R.; Norman, John H.
1983-01-01
Liquid hydrogen iodide is decomposed to form hydrogen and iodine in the presence of water using a soluble catalyst. Decomposition is carried out at a temperature between about 350.degree. K. and about 525.degree. K. and at a corresponding pressure between about 25 and about 300 atmospheres in the presence of an aqueous solution which acts as a carrier for the homogeneous catalyst. Various halides of the platinum group metals, particularly Pd, Rh and Pt, are used, particularly the chlorides and iodides which exhibit good solubility. After separation of the H.sub.2, the stream from the decomposer is countercurrently extracted with nearly dry HI to remove I.sub.2. The wet phase contains most of the catalyst and is recycled directly to the decomposition step. The catalyst in the remaining almost dry HI-I.sub.2 phase is then extracted into a wet phase which is also recycled. The catalyst-free HI-I.sub.2 phase is finally distilled to separate the HI and I.sub.2. The HI is recycled to the reactor; the I.sub.2 is returned to a reactor operating in accordance with the Bunsen equation to create more HI.
Coxeter decompositions of hyperbolic simplexes
Felikson, A A
2002-12-31
A Coxeter decomposition of a polyhedron in a hyperbolic space H{sup n} is a decomposition of it into finitely many Coxeter polyhedra such that any two tiles having a common facet are symmetric with respect to it. The classification of Coxeter decompositions is closely related to the problem of the classification of finite-index subgroups generated by reflections in discrete hyperbolic groups generated by reflections. All Coxeter decompositions of simplexes in the hyperbolic spaces H{sup n} with n>3 are described in this paper.
Agakishiev, G.; Arnold, O.; Belver, D.; Belyaev, A.; Berger-Chen, J. C.; Blanco, A.; Böhmer, M.; Boyard, J. L.; Cabanelas, P.; Chernenko, S.; Dybczak, A.; Epple, E.; Fabbietti, L.; Fateev, O.; Finocchiaro, P.; Fonte, P.; Friese, J.; Fröhlich, I.; Galatyuk, T.; Garzón, J. A.; Gernhäuser, R.; Göbel, K.; Golubeva, M.; González-Díaz, D.; Guber, F.; Gumberidze, M.; Heinz, T.; Hennino, T.; Holzmann, R.; Ierusalimov, A.; Iori, I.; Ivashkin, A.; Jurkovic, M.; Kämpfer, B.; Karavicheva, T.; Koenig, I.; Koenig, W.; Kolb, B. W.; Kornakov, G.; Kotte, R.; Krása, A.; Krizek, F.; Krücken, R.; Kuc, H.; Kühn, W.; Kugler, A.; Kunz, T.; Kurepin, A.; Ladygin, V.; Lalik, R.; Lapidus, K.; Lebedev, A.; Lopes, L.; Lorenz, M.; Maier, L.; Mangiarotti, A.; Markert, J.; Metag, V.; Michel, J.; Müntz, C.; Münzer, R.; Naumann, L.; Pachmayer, Y. C.; Palka, M.; Parpottas, Y.; Pechenov, V.; Pechenova, O.; Pietraszko, J.; Przygoda, W.; Ramstein, B.; Reshetin, A.; Rustamov, A.; Sadovsky, A.; Salabura, P.; Schmah, A.; Schwab, E.; Siebenson, J.; Sobolev, Yu. G.; Spataro, S.; Spruck, B.; Ströbele, H.; Stroth, J.; Sturm, C.; Tarantola, A.; Teilab, K.; Tlusty, P.; Traxler, M.; Tsertos, H.; Vasiliev, T.; Wagner, V.; Weber, M.; Wendisch, C.; Wüstenfeld, J.; Yurevich, S.; Zanevsky, Y.; Sarantsev, A. V.
2015-01-26
Employing the Bonn–Gatchina partial wave analysis framework (PWA), we have analyzed HADES data of the reaction p(3.5GeV) + p → pK^{+}Λ. This reaction might contain information about the kaonic cluster “ppK^{-}” (with quantum numbers J^{P}=0^{-} and total isospin I =1/2) via its decay into pΛ. Due to interference effects in our coherent description of the data, a hypothetical K ¯NN (or, specifically “ppK^{-}”) cluster signal need not necessarily show up as a pronounced feature (e.g. a peak) in an invariant mass spectrum like pΛ. Our PWA analysis includes a variety of resonant and non-resonant intermediate states and delivers a good description of our data (various angular distributions and two-hadron invariant mass spectra) without a contribution of a K ¯NN cluster. At a confidence level of CL_{s}=95% such a cluster cannot contribute more than 2–12% to the total cross section with a pK^{+} Λ final state, which translates into a production cross-section between 0.7 μb and 4.2 μb, respectively. The range of the upper limit depends on the assumed cluster mass, width and production process.
Partial wave analysis of the reaction $\gamma p\to p\omega $ and the search for nucleon resonances
Williams, M.; Applegate, D.; Bellis, M.; Meyer, C. A.; Adhikari, K. P.; Anghinolfi, M.; Baghdasaryan, H.; Ball, J.; Battaglieri, M.; Bedlinskiy, I.; Berman, B. L.; Biselli, A. S.; Briscoe, W. J.; Brooks, W. K.; Burkert, V. D.; Careccia, S. L.; Carman, D. S.; Cole, P. L.; Collins, P.; Crede, V.; D’Angelo, A.; Daniel, A.; De Vita, R.; De Sanctis, E.; Deur, A.; Dey, B.; Dhamija, S.; Dickson, R.; Djalali, C.; Dodge, G. E.; Doughty, D.; Dugger, M.; Dupre, R.; Alaoui, A. El; Elouadrhiri, L.; Eugenio, P.; Fedotov, G.; Fegan, S.; Fradi, A.; Gabrielyan, M. Y.; Garçon, M.; Gilfoyle, G. P.; Giovanetti, K. L.; Girod, F. X.; Gohn, W.; Golovatch, E.; Gothe, R. W.; Griffioen, K. A.; Guidal, M.; Guler, N.; Guo, L.; Hafidi, K.; Hakobyan, H.; Hanretty, C.; Hassall, N.; Hicks, K.; Holtrop, M.; Ilieva, Y.; Ireland, D. G.; Ishkhanov, B. S.; Isupov, E. L.; Jawalkar, S. S.; Jo, H. S.; Johnstone, J. R.; Joo, K.; Keller, D.; Khandaker, M.; Khetarpal, P.; Kim, W.; Klein, A.; Klein, F. J.; Krahn, Z.; Kubarovsky, V.; Kuleshov, S. V.; Kuznetsov, V.; Livingston, K.; Lu, H. Y.; Mayer, M.; McAndrew, J.; McCracken, M. E.; McKinnon, B.; Mirazita, M.; Mokeev, V.; Moreno, B.; Moriya, K.; Morrison, B.; Munevar, E.; Nadel-Turonski, P.; Nepali, C. S.; Niccolai, S.; Niculescu, G.; Niculescu, I.; Niroula, M. R.; Niyazov, R. A.; Osipenko, M.; Ostrovidov, A. I.; Paris, M.; Park, K.; Park, S.; Pasyuk, E.; Pereira, S. Anefalos; Perrin, Y.; Pisano, S.; Pogorelko, O.; Pozdniakov, S.; Price, J. W.; Procureur, S.; Protopopescu, D.; Ricco, G.; Ripani, M.; Ritchie, B. G.; Rosner, G.; Rossi, P.; Sabatié, F.; Saini, M. S.; Salamanca, J.; Salgado, C.; Schott, D.; Schumacher, R. A.; Seraydaryan, H.; Sharabian, Y. G.; Smith, E. S.; Sober, D. I.; Sokhan, D.; Stepanyan, S. S.; Stoler, P.; Strakovsky, I. I.; Strauch, S.; Taiuti, M.; Tedeschi, D. J.; Tkachenko, S.; Ungaro, M.; Vineyard, M. F.; Voutier, E.; Watts, D. P.; Weygand, D. P.; Wood, M. H.; Zhang, J.; Zhao, B.
2009-12-30
We performed an event-based partial wave analysis (PWA) of the reaction γ p -> p ω on a high-statistics dataset obtained using the CLAS at Jefferson Lab for center-of-mass energies from threshold up to 2.4 GeV. This analysis benefits from access to the world's first high precision spin density matrix element measurements, available to the event-based PWA through the decay distribution of omega-> π^{+} π^{ -} π^{0}. The data confirm the dominance of the t-channel π^{0} exchange amplitude in the forward direction. The dominant resonance contributions are consistent with the previously identified states F[15](1680) and D[13](1700) near threshold, as well as the G[17](2190) at higher energies. Suggestive evidence for the presence of a J(P)=5/2^{+} state around 2 GeV, a "missing" state, has also been found. Evidence for other states is inconclusive.
Qu, Chang-Feng; Song, Jin-Ming; Li, Ning; Li, Xue-Gang; Yuan, Hua-Mao; Duan, Li-Qin; Ma, Qing-Xia
2015-08-15
A growing body of evidence suggests that the jellyfish population in Chinese seas is increasing, and decomposition of jellyfish strongly influences the marine ecosystem. This study investigated the change in water quality during Cyanea nozakii decomposition using simulation experiments. The results demonstrated that the amount of dissolved nutrients released by jellyfish was greater than the amount of particulate nutrients. NH4(+) was predominant in the dissolved matter, whereas the particulate matter was dominated by organic nitrogen and inorganic phosphorus. The high N/P ratios demonstrated that jellyfish decomposition may result in high nitrogen loads. The inorganic nutrients released by C. nozakii decomposition were important for primary production. Jellyfish decomposition caused decreases in the pH and oxygen consumption associated with acidification and hypoxia or anoxia; however, sediments partially mitigated the changes in the pH and oxygen. These results imply that jellyfish decomposition can result in potentially detrimental effects on marine environments. PMID:26088540
Erbium hydride decomposition kinetics.
Ferrizz, Robert Matthew
2006-11-01
Thermal desorption spectroscopy (TDS) is used to study the decomposition kinetics of erbium hydride thin films. The TDS results presented in this report are analyzed quantitatively using Redhead's method to yield kinetic parameters (E{sub A} {approx} 54.2 kcal/mol), which are then utilized to predict hydrogen outgassing in vacuum for a variety of thermal treatments. Interestingly, it was found that the activation energy for desorption can vary by more than 7 kcal/mol (0.30 eV) for seemingly similar samples. In addition, small amounts of less-stable hydrogen were observed for all erbium dihydride films. A detailed explanation of several approaches for analyzing thermal desorption spectra to obtain kinetic information is included as an appendix.
Chen Xiangsong; Sun Weimin; Wang Fan; Goldman, T.
2011-04-01
We analyze the problem of spin decomposition for an interacting system from a natural perspective of constructing angular-momentum eigenstates. We split, from the total angular-momentum operator, a proper part which can be separately conserved for a stationary state. This part commutes with the total Hamiltonian and thus specifies the quantum angular momentum. We first show how this can be done in a gauge-dependent way, by seeking a specific gauge in which part of the total angular-momentum operator vanishes identically. We then construct a gauge-invariant operator with the desired property. Our analysis clarifies what is the most pertinent choice among the various proposals for decomposing the nucleon spin. A similar analysis is performed for extracting a proper part from the total Hamiltonian to construct energy eigenstates.
Direct Sum Decomposition of Groups
ERIC Educational Resources Information Center
Thaheem, A. B.
2005-01-01
Direct sum decomposition of Abelian groups appears in almost all textbooks on algebra for undergraduate students. This concept plays an important role in group theory. One simple example of this decomposition is obtained by using the kernel and range of a projection map on an Abelian group. The aim in this pedagogical note is to establish a direct…
Biogeochemistry of Decomposition and Detrital Processing
NASA Astrophysics Data System (ADS)
Sanderman, J.; Amundson, R.
2003-12-01
Decomposition is a key ecological process that roughly balances net primary production in terrestrial ecosystems and is an essential process in resupplying nutrients to the plant community. Decomposition consists of three concurrent processes: communition or fragmentation, leaching of water-soluble compounds, and microbial catabolism. Decomposition can also be viewed as a sequential process, what Eijsackers and Zehnder (1990) compare to a Russian matriochka doll. Soil macrofauna fragment and partially solubilize plant residues, facilitating establishment of a community of decomposer microorganisms. This decomposer community will gradually shift as the most easily degraded plant compounds are utilized and the more recalcitrant materials begin to accumulate. Given enough time and the proper environmental conditions, most naturally occurring compounds can completely be mineralized to inorganic forms. Simultaneously with mineralization, the process of humification acts to transform a fraction of the plant residues into stable soil organic matter (SOM) or humus. For reference, Schlesinger (1990) estimated that only ˜0.7% of detritus eventually becomes stabilized into humus.Decomposition plays a key role in the cycling of most plant macro- and micronutrients and in the formation of humus. Figure 1 places the roles of detrital processing and mineralization within the context of the biogeochemical cycling of essential plant nutrients. Chapin (1991) found that while the atmosphere supplied 4% and mineral weathering supplied no nitrogen and <1% of phosphorus, internal nutrient recycling is the source for >95% of all the nitrogen and phosphorus uptake by tundra species in Barrow, Alaska. In a cool temperate forest, nutrient recycling accounted for 93%, 89%, 88%, and 65% of total sources for nitrogen, phosphorus, potassium, and calcium, respectively ( Chapin, 1991). (13K)Figure 1. A decomposition-centric biogeochemical model of nutrient cycling. Although there is significant
Biogeochemistry of Decomposition and Detrital Processing
NASA Astrophysics Data System (ADS)
Sanderman, J.; Amundson, R.
2003-12-01
Decomposition is a key ecological process that roughly balances net primary production in terrestrial ecosystems and is an essential process in resupplying nutrients to the plant community. Decomposition consists of three concurrent processes: communition or fragmentation, leaching of water-soluble compounds, and microbial catabolism. Decomposition can also be viewed as a sequential process, what Eijsackers and Zehnder (1990) compare to a Russian matriochka doll. Soil macrofauna fragment and partially solubilize plant residues, facilitating establishment of a community of decomposer microorganisms. This decomposer community will gradually shift as the most easily degraded plant compounds are utilized and the more recalcitrant materials begin to accumulate. Given enough time and the proper environmental conditions, most naturally occurring compounds can completely be mineralized to inorganic forms. Simultaneously with mineralization, the process of humification acts to transform a fraction of the plant residues into stable soil organic matter (SOM) or humus. For reference, Schlesinger (1990) estimated that only ˜0.7% of detritus eventually becomes stabilized into humus.Decomposition plays a key role in the cycling of most plant macro- and micronutrients and in the formation of humus. Figure 1 places the roles of detrital processing and mineralization within the context of the biogeochemical cycling of essential plant nutrients. Chapin (1991) found that while the atmosphere supplied 4% and mineral weathering supplied no nitrogen and <1% of phosphorus, internal nutrient recycling is the source for >95% of all the nitrogen and phosphorus uptake by tundra species in Barrow, Alaska. In a cool temperate forest, nutrient recycling accounted for 93%, 89%, 88%, and 65% of total sources for nitrogen, phosphorus, potassium, and calcium, respectively ( Chapin, 1991). (13K)Figure 1. A decomposition-centric biogeochemical model of nutrient cycling. Although there is significant
Ammonia decomposition catalysis using lithium-calcium imide.
Makepeace, Joshua W; Hunter, Hazel M A; Wood, Thomas J; Smith, Ronald I; Murray, Claire A; David, William I F
2016-07-01
Lithium-calcium imide is explored as a catalyst for the decomposition of ammonia. It shows the highest ammonia decomposition activity yet reported for a pure light metal amide or imide, comparable to lithium imide-amide at high temperature, with superior conversion observed at lower temperatures. Importantly, the post-reaction mass recovery of lithium-calcium imide is almost complete, indicating that it may be easier to contain than the other amide-imide catalysts reported to date. The basis of this improved recovery is that the catalyst is, at least partially, solid across the temperature range studied under ammonia flow. However, lithium-calcium imide itself is only stable at low and high temperatures under ammonia, with in situ powder diffraction showing the decomposition of the catalyst to lithium amide-imide and calcium imide at intermediate temperatures of 200-460 °C. PMID:27092374
NASA Astrophysics Data System (ADS)
Kim, E.-H.; Boardsen, S. A.; Johnson, J. R.; Slavin, J. A.
2016-02-01
This chapter provides a brief overview of the observed characteristics of ultra-low-frequency (ULF) waves at Mercury. It shows how field-aligned propagating ULF waves at Mercury can be generated by externally driven fast compressional waves (FWs) via mode conversion at the ion-ion hybrid resonance. Then, the chapter reviews the interpretation that the strong magnetic compressional waves near and its harmonics observed with 20 of Mercury's magnetic equator could be the ion Bernstein wave (IBW) mode. A recent statistical study of ULF waves at Mercury based on MESSENGER data reported the occurrence and polarization of the detected waves. The chapter further introduces the field line resonance and the electromagnetic ion Bernstein waves to explain such waves, and shows that both theories can partially explain the observations.
Singular value decomposition of optically-mapped cardiac rotors and fibrillatory activity
NASA Astrophysics Data System (ADS)
Rabinovitch, A.; Biton, Y.; Braunstein, D.; Friedman, M.; Aviram, I.; Yandrapalli, S.; Pandit, S. V.; Berenfeld, O.
2015-03-01
Our progress of understanding how cellular and structural factors contribute to arrhythmia is hampered in part because of controversies as to whether a fibrillating heart is driven by a single, several, or multiple number of sources, whether they are focal or reentrant and how to localize them. Here we demonstrate how a novel usage of the neutral singular value decomposition (SVD) method enables the extraction of the governing spatial and temporal modes of excitation from a rotor and fibrillatory waves. Those modes highlight patterns and regions of organization in the midst of the otherwise seemingly random propagating excitation waves. We apply the method to experimental models of cardiac fibrillation in rabbit hearts. We show that SVD analysis is able to enhance the classification of the heart electrical patterns into regions harboring drivers in the form of fast reentrant activity and other regions of by-standing activity. This enhancement is accomplished without any prior assumptions regarding the spatial, temporal or spectral properties of those drivers. The analysis corroborates that the dominant mode has the highest activation rate and further reveals a new feature: a transfer of modes from the driving to passive regions resulting in a partial reaction of the passive region to the driving region.
Singular Value Decomposition of Optically-Mapped Cardiac Rotors and Fibrillatory Activity
Rabinovitch, A.; Biton, Y.; Braunstein, D.; Friedman, M.; Aviram, I.; Yandrapalli, S.; Pandit, S. V.; Berenfeld, O.
2015-01-01
Our progress of understanding how cellular and structural factors contribute to the arrhythmia is hampered in part because of controversies whether a fibrillating heart is driven by a single, several, or multiple number of sources, and whether they are focal or reentrant, and how to localize them. Here we demonstrate how a novel usage of the neutral singular value decomposition (SVD) method enables the extraction of the governing spatial and temporal modes of excitation from a rotor and fibrillatory waves. Those modes highlight patterns and regions of organization in the midst of the otherwise seemingly-randomly propagating excitation waves. We apply the method to experimental models of cardiac fibrillation in rabbit hearts. We show that the SVD analysis is able to enhance the classification of the heart electrical patterns into regions harboring drivers in the form of fast reentrant activity and other regions of by-standing activity. This enhancement is accomplished without any prior assumptions regarding the spatial, temporal or spectral properties of those drivers. The analysis corroborates that the dominant mode has the highest activation rate and further reveals a new feature: A transfer of modes from the driving to the passive regions resulting in a partial reaction of the passive region to the driving region. PMID:26668401
Decomposition in northern Minnesota peatlands
Farrish, K.W.
1985-01-01
Decomposition in peatlands was investigated in northern Minnesota. Four sites, an ombrotrophic raised bog, an ombrotrophic perched bog and two groundwater minerotrophic fens, were studied. Decomposition rates of peat and paper were estimated using mass-loss techniques. Environmental and substrate factors that were most likely to be responsible for limiting decomposition were monitored. Laboratory incubation experiments complemented the field work. Mass-loss over one year in one of the bogs, ranged from 11 percent in the upper 10 cm of hummocks to 1 percent at 60 to 100 cm depth in hollows. Regression analysis of the data for that bog predicted no mass-loss below 87 cm. Decomposition estimates on an area basis were 2720 and 6460 km/ha yr for the two bogs; 17,000 and 5900 kg/ha yr for the two fens. Environmental factors found to limit decomposition in these peatlands were reducing/anaerobic conditions below the water table and cool peat temperatures. Substrate factors found to limit decomposition were low pH, high content of resistant organics such as lignin, and shortages of available N and K. Greater groundwater influence was found to favor decomposition through raising the pH and perhaps by introducing limited amounts of dissolved oxygen.
Slow spinodal decomposition in binary liquid mixtures of polymers
NASA Astrophysics Data System (ADS)
Izumitani, Tatsuo; Hashimoto, Takeji
1985-10-01
Isothermal demixing process of binary polymer mixtures of SBR (styrene-butadiene random copolymer) and polybutadiene at deep quench depths was investigated by time-resolved light scattering technique. The results indicated that the systems undergo extremely slow spinodal decomposition of the type as adequately characterized by Cahn's linearized theory in the early stage and in the small q regime (q≲qmax≂105 cm-1) covered in this experiment where q is wave number of growing fluctuations and qmax is the q value having maximum growth rate. The spinodal decomposition studied in this work was that in the diffusion-control regime, and in the slowest case of the decomposition, the early stage was found to extend up to about 80 min, corresponding to the reduced time τ about 2.7. The shortest reduced time achieved in this experiment is about 0.03.
Domain decomposition methods for solving an image problem
Tsui, W.K.; Tong, C.S.
1994-12-31
The domain decomposition method is a technique to break up a problem so that ensuing sub-problems can be solved on a parallel computer. In order to improve the convergence rate of the capacitance systems, pre-conditioned conjugate gradient methods are commonly used. In the last decade, most of the efficient preconditioners are based on elliptic partial differential equations which are particularly useful for solving elliptic partial differential equations. In this paper, the authors apply the so called covering preconditioner, which is based on the information of the operator under investigation. Therefore, it is good for various kinds of applications, specifically, they shall apply the preconditioned domain decomposition method for solving an image restoration problem. The image restoration problem is to extract an original image which has been degraded by a known convolution process and additive Gaussian noise.
Structural optimization by multilevel decomposition
NASA Technical Reports Server (NTRS)
Sobieszczanski-Sobieski, J.; James, B.; Dovi, A.
1983-01-01
A method is described for decomposing an optimization problem into a set of subproblems and a coordination problem which preserves coupling between the subproblems. The method is introduced as a special case of multilevel, multidisciplinary system optimization and its algorithm is fully described for two level optimization for structures assembled of finite elements of arbitrary type. Numerical results are given for an example of a framework to show that the decomposition method converges and yields results comparable to those obtained without decomposition. It is pointed out that optimization by decomposition should reduce the design time by allowing groups of engineers, using different computers to work concurrently on the same large problem.
Perfluoropolyalkylether decomposition on catalytic aluminas
NASA Technical Reports Server (NTRS)
Morales, Wilfredo
1994-01-01
The decomposition of Fomblin Z25, a commercial perfluoropolyalkylether liquid lubricant, was studied using the Penn State Micro-oxidation Test, and a thermal gravimetric/differential scanning calorimetry unit. The micro-oxidation test was conducted using 440C stainless steel and pure iron metal catalyst specimens, whereas the thermal gravimetric/differential scanning calorimetry tests were conducted using catalytic alumina pellets. Analysis of the thermal data, high pressure liquid chromatography data, and x-ray photoelectron spectroscopy data support evidence that there are two different decomposition mechanisms for Fomblin Z25, and that reductive sites on the catalytic surfaces are responsible for the decomposition of Fomblin Z25.
Autonomous Gaussian Decomposition
NASA Astrophysics Data System (ADS)
Lindner, Robert R.; Vera-Ciro, Carlos; Murray, Claire E.; Stanimirović, Snežana; Babler, Brian; Heiles, Carl; Hennebelle, Patrick; Goss, W. M.; Dickey, John
2015-04-01
We present a new algorithm, named Autonomous Gaussian Decomposition (AGD), for automatically decomposing spectra into Gaussian components. AGD uses derivative spectroscopy and machine learning to provide optimized guesses for the number of Gaussian components in the data, and also their locations, widths, and amplitudes. We test AGD and find that it produces results comparable to human-derived solutions on 21 cm absorption spectra from the 21 cm SPectral line Observations of Neutral Gas with the EVLA (21-SPONGE) survey. We use AGD with Monte Carlo methods to derive the H i line completeness as a function of peak optical depth and velocity width for the 21-SPONGE data, and also show that the results of AGD are stable against varying observational noise intensity. The autonomy and computational efficiency of the method over traditional manual Gaussian fits allow for truly unbiased comparisons between observations and simulations, and for the ability to scale up and interpret the very large data volumes from the upcoming Square Kilometer Array and pathfinder telescopes.