Single Scattering Detection in Turbin Media Using Single-Phase Structured Illumination Filtering
Berrocal, E.; Johnsson, J.; Kristensson, E.; Alden, M.
2012-05-01
This work shows a unique possibility of visualizing the exponential intensity decay due to light extinction, when laser adiation propagates through a homogeneous scattering edium. This observation implies that the extracted intensity mostly riginates from single scattering events. The filtering of this single light scattering intensity is performed by means of a single-phase structured illumination filtering approach. Results from numerical Monte Carlo simulation confirm the experimental findings for an extinction coefficient of μ_e = 0.36 mm^-1. This article demonstrates an original and reliable way of measuring the extinction coefficient of particulate turbid media based on sidescattering imaging. Such an approach has capabilities to replace the commonly used transmission measurement within the intermediate single-to multiple scattering regime where the optical depth ranges between 1 procedure and set-up. Applications of the technique has potential in probing challenging homogeneous scattering media, such as biomedical tissues, turbid emulsions, etc, in situations where dilution cannot be applied and where conventional transmission measurements fail.
Investigation of snow single scattering properties based on first order Legendre phase function
Eppanapelli, Lavan Kumar; Casselgren, Johan; Wåhlin, Johan; Sjödahl, Mikael
2017-04-01
Angularly resolved bidirectional reflectance measurements were modelled by approximating a first order Legendre expanded phase function to retrieve single scattering properties of snow. The measurements from 10 different snow types with known density and specific surface area (SSA) were investigated. A near infrared (NIR) spectrometer was used to measure reflected light above the snow surface over the hemisphere in the wavelength region of 900-1650 nm. A solver based on discrete ordinate radiative transfer (DISORT) model was used to retrieve the estimated Legendre coefficients of the phase function and a correlation between the coefficients and physical properties of different snow types is investigated. Results of this study suggest that the first two coefficients of the first order Legendre phase function provide sufficient information about the physical properties of snow where the latter captures the anisotropic behaviour of snow and the former provides a relative estimate of the single scattering albedo of snow. The coefficients of the first order phase function were compared with the experimental data and observed that both the coefficients are in good agreement with the experimental data. These findings suggest that our approach can be applied as a qualitative tool to investigate physical properties of snow and also to classify different snow types.
Trunk, M; Lübben, J F; Popp, J; Schrader, B; Kiefer, W
1997-05-20
Light-scattering measurements of optically levitated microdroplets containing three components, glycerin, water, and ammonium sulfate, are presented. Evaporation of the microdroplet is studied by means of morphology-dependent resonances observed in both Raman spectra as well as elastically scattered light and by the simultaneous measurement of the laser power. The phase transition from the liquid to the solid state of ammonium sulfate inside the microdroplet is observed by means of morphology-dependent resonances and Raman scattering.
International Nuclear Information System (INIS)
Rosenberg, L.; Spruch, L.
1996-01-01
Levinson close-quote s theorem relates the zero-energy phase shift δ for potential scattering in a given partial wave l, by a spherically symmetric potential that falls off sufficiently rapidly, to the number of bound states of that l supported by the potential. An extension of this theorem is presented that applies to single-channel scattering by a compound system initially in its ground state. As suggested by Swan [Proc. R. Soc. London Ser. A 228, 10 (1955)], the extended theorem differs from that derived for potential scattering; even in the absence of composite bound states δ may differ from zero as a consequence of the Pauli principle. The derivation given here is based on the introduction of a continuous auxiliary open-quote open-quote length phase close-quote close-quote η, defined modulo π for l=0 by expressing the scattering length as A=acotη, where a is a characteristic length of the target. Application of the minimum principle for the scattering length determines the branch of the cotangent curve on which η lies and, by relating η to δ, an absolute determination of δ is made. The theorem is applicable, in principle, to single-channel scattering in any partial wave for e ± -atom and nucleon-nucleus systems. In addition to a knowledge of the number of composite bound states, information (which can be rather incomplete) concerning the structure of the target ground-state wave function is required for an explicit, absolute, determination of the phase shift δ. As for Levinson close-quote s original theorem for potential scattering, no additional information concerning the scattering wave function or scattering dynamics is required. copyright 1996 The American Physical Society
International Nuclear Information System (INIS)
Al-Asadi, H A; Mahdi, M A; Bakar, A A A; Adikan, F R Mahamd
2011-01-01
We present a theoretical study of nonlinear phase shift through stimulated Brillouin scattering in single mode optical fiber. Analytical expressions describing the nonlinear phase shift for the pump and Stokes waves in the pump power recycling technique have been derived. The dependence of the nonlinear phase shift on the optical fiber length, the reflectivity of the optical mirror and the frequency detuning coefficient have been analyzed for different input pump power values. We found that with the recycling pump technique, the nonlinear phase shift due to stimulated Brillouin scattering reduced to less than 0.1 rad for 5 km optical fiber length and 0.65 reflectivity of the optical mirror, respectively, at an input pump power equal to 30 mW
Directory of Open Access Journals (Sweden)
Qiang Yang
2015-03-01
Full Text Available Focusing light though scattering media beyond the ballistic regime is a challenging task in biomedical optical imaging. This challenge can be overcome by wavefront shaping technique, in which a time-reversed (TR wavefront of scattered light is generated to suppress the scattering. In previous TR optical focusing experiments, a phase-only spatial light modulator (SLM has been typically used to control the wavefront of incident light. Unfortunately, although the phase information is reconstructed by the phase-only SLM, the amplitude information is lost, resulting in decreased peak-to-background ratio (PBR of optical focusing in the TR wavefront reconstruction. A new method of TR optical focusing through scattering media is proposed here, which numerically reconstructs the full phase and amplitude of a simulated scattered light field by using a single phase-only SLM. Simulation results and the proposed optical setup show that the time-reversal of a fully developed speckle field can be digitally implemented with both phase and amplitude recovery, affording a way to improve the performance of light focusing through scattering media.
Raman scattering study of the structural phase transition in single crystal KDy(MoO4)2
Peschanskii, A. V.
2017-11-01
Raman scattering of light in single-crystal KDy(MoO4)2 is studied at frequencies of 3-1000 cm-1 for temperatures ranging from 2 to 300 K, including that of a structural phase transition of the cooperative Jahn-Teller type (TC ˜ 14.5 K). During the transition to the low-temperature phase, a series of additional phonon lines corresponding to the Ag, B1g, B2g, and B3g modes is observed which indicates a doubling of the unit cell during the phase transition. An analysis of the symmetry of the phonon modes shows that the low-temperature phase has a predominantly monoclinic symmetry with conservation of a second order axis along the crystallographic b direction, i.e., perpendicular to the layers. Excitations are discovered which correspond to low-energy electronic transitions between levels of the ground-state 6H15/2 multiplet of the Dy3+ ion, which is split in the crystal field with a C2 symmetry. In the vicinity of the first excited Kramers doublet of the Dy3+ ion in crystalline KDy(MoO4)2, the scattered spectrum contains four lines [16.5, 21.0, 24.9, and 29.1 cm-1 (2 K)] at low temperatures, instead of a single line [18.3 cm-1 (25 K)] above the phase transition temperature (14.5 K). This indicates the existence of four nonequivalent dysprosium ions in the low-temperature phase.
Gnezdilov, V. P.; Pashkevich, Yu. G.; Tranquada, J. M.; Lemmens, P.; Guentherodt, G.; Yeremenko, A. V.; Barilo, S. N.; Shiryaev, S. V.; Kurnevich, L. A.; Gehring, P. M.
2004-01-01
We report a neutron and Raman scattering study of a single-crystal of La(2)CuO(4.05) prepared by high temperature electrochemical oxidation. Elastic neutron scattering measurements show the presence of two phases, corresponding to the two edges of the first miscibility gap, all the way up to 300 K. An additional oxygen redistribution, driven by electronic energies, is identified at 250 K in Raman scattering (RS) experiments by the simultaneous onset of two-phonon and two-magnon scattering, wh...
Directory of Open Access Journals (Sweden)
Seonhyeop Shin
2015-06-01
Full Text Available The elastic properties of KF-substituted perovskite lead titanate (PbTiO3 were investigated by dielectric measurements and Brillouin light scattering. The ferroelectric phase transition occurred at substantially lower temperature due to KF substitution, which was attributed to the modification of the covalency in Pb–O and Ti–O bonds. The longitudinal acoustic (LA mode of KF-substituted PbTiO3 showed a frequency softening in the paraelectric phase, which was accompanied by increasing acoustic damping. This indicated that polarization fluctuations responsible for the acoustic anomalies were enhanced by KF substitution.
Single scattering properties of hydrosols
Mukherjee, L.; Zhai, P.; Hu, Y.
2017-12-01
The single scattering or inherent optical properties (IOPs) of hydrosols play an important role in the complete study of ocean optics, ocean color remote sensing, and ocean biogeochemistry research. Measurements show that hydrosols can be of various sizes and shapes, which suggests that general non-spherical models should be considered for the study of IOPs of hydrosols. In this work, the IOPs of randomly oriented non-spherical hydrosols of both absorbing and non-absorbing types are modeled using the Amsterdam Discrete Dipole Approximation (ADDA). We have defined the degree of optical non-sphericity (DONS) and investigated the dependence of DONS on refractive indices, sizes, and aspect ratios. For particles with non-unit aspect ratios, the magnitude of DONS increases with an increase of refractive index and aspect ratio. In general, the value of DONS increases with increase in particle size. The variation of DONS with respect to refractive indices and aspect ratios of the hydrosols makes it an important parameter in the study of ocean optics. Dependence of backscattering fraction on non-sphericity, size, and aspect ratio of the hydrosols is also demonstrated. The modeling of single scattering properties of hydrosols with different microphysical parameters would help to interpret the ocean radiation field measured by in situ or remote sensing sensors. Understanding the IOPs of hydrosols would lead to better radiative transfer models in ocean waters and new remote sensing technologies of hydrosol compositions.
Phase transitions and neutron scattering
International Nuclear Information System (INIS)
Shirane, G.
1993-01-01
A review is given of recent advances in neutron scattering studies of solid state physics. I have selected the study of a structural phase transition as the best example to demonstrate the power of neutron scattering techniques. Since energy analysis is relatively easy, the dynamical aspects of a transition can be elucidated by the neutron probe. I shall discuss in some detail current experiments on the 100 K transition in SrTiO 3 , the crystal which has been the paradigm of neutron studies of phase transitions for many years. This new experiment attempts to clarify the relation between the neutron central peak, observed in energy scans, and the two length scales observed in recent x-ray diffraction studies where only scans in momentum space are possible. (author)
Phase transitions and neutron scattering
International Nuclear Information System (INIS)
Shirane, G.
1993-01-01
A review is given of recent advances in neutron scattering studies of solid state physics. The author has selected the study of a structural phase transition as the best example to demonstrate the power of neutron scattering techniques. Since energy analysis is relatively easy, the dynamical aspects of a transition can be elucidated by the neutron probe. He will discuss in some detail current experiments on the 100K transition in SrTiO 3 , the crystal which has been the paradigm of neutron studies of phase transitions for many years. This new experiment attempts to clarify the relation between the neutron central peak, observed in energy scans, and the two length scales observed in recent x-ray diffraction studies where only scans in momentum space are possible
Luo, Chengtao; Bansal, Dipanshu; Li, Jiefang; Viehland, Dwight; Winn, Barry; Ren, Yang; Li, Xiaobing; Luo, Haosu; Delaire, Olivier
2017-11-01
Neutron and x-ray scattering measurements were performed on (N a1 /2B i1 /2 ) Ti O3-x at %BaTi O3 (NBT-x BT ) single crystals (x =4 , 5, 6.5, and 7.5) across the morphotropic phase boundary (MPB), as a function of both composition and temperature, and probing both structural and dynamical aspects. In addition to the known diffuse scattering pattern near the Γ points, our measurements revealed new, faint superlattice peaks, as well as an extensive diffuse scattering network, revealing a short-range ordering of polar nanoregions (PNR) with a static stacking morphology. In samples with compositions closest to the MPB, our inelastic neutron scattering investigations of the phonon dynamics showed two unusual features in the acoustic phonon branches, between the superlattice points, and between the superlattice points and Γ points, respectively. These critical elements are not present in the other compositions away from the MPB, which suggests that these features may be related to the tilt modes coupling behavior near the MPB.
Light scattering near phase transitions
Cummins, HZ
1983-01-01
Since the development of the laser in the early 1960's, light scattering has played an increasingly crucial role in the investigation of many types of phase transitions and the published work in this field is now widely dispersed in a large number of books and journals.A comprehensive overview of contemporary theoretical and experimental research in this field is presented here. The reviews are written by authors who have actively contributed to the developments that have taken place in both Eastern and Western countries.
Single Crystal Diffuse Neutron Scattering
Directory of Open Access Journals (Sweden)
Richard Welberry
2018-01-01
Full Text Available Diffuse neutron scattering has become a valuable tool for investigating local structure in materials ranging from organic molecular crystals containing only light atoms to piezo-ceramics that frequently contain heavy elements. Although neutron sources will never be able to compete with X-rays in terms of the available flux the special properties of neutrons, viz. the ability to explore inelastic scattering events, the fact that scattering lengths do not vary systematically with atomic number and their ability to scatter from magnetic moments, provides strong motivation for developing neutron diffuse scattering methods. In this paper, we compare three different instruments that have been used by us to collect neutron diffuse scattering data. Two of these are on a spallation source and one on a reactor source.
DEFF Research Database (Denmark)
Golestan, Saeed; Guerrero, Josep M.; Quintero, Juan Carlos Vasquez
2017-01-01
Single-phase phase-locked loops (PLLs) are popular for the synchronization and control of single-phase gridconnected converters. They are also widely used for monitoring and diagnostic purposes in the power and energy areas. In recent years, a large number of single-phase PLLs with different...... structures and properties have been proposed in the literature. The main aim of this paper is to provide a review of these PLLs. To this end, the single-phase PLLs are first classified into two major categories: 1) power-based PLLs (pPLLs), and 2) quadrature signal generation-based PLLs (QSG......-PLLs). The members of each category are then described and their pros and cons are discussed. This work provides a deep insight into characteristics of different single-phase PLLs and, therefore, can be considered as a reference for researchers and engineers....
Applications of phase conjugate mirror to Thomson scattering diagnostics (invited)
International Nuclear Information System (INIS)
Hatae, T.; Naito, O.; Nakatsuka, M.; Yoshida, H.
2006-01-01
A high performance phase conjugate mirror based on stimulated Brillouin scattering (SBS-PCM) has been applied to the Thomson scattering system in the JT-60U tokamak for the first time in order to improve the measurement performance. A SBS-PCM realized a high reflectivity of 95% at a high input power of 145 W (2.9 J, 50 Hz). Using the SBS-PCM, two methods have been developed to increase the intensity of scattered light. For the first method, we have developed a new optical design to provide a double-pass scattering method with the SBS-PCM. A laser beam passing through the plasma is reflected by the SBS-PCM. The reflected beam passes the plasma again along the same path by means of the phase conjugation of the optically nonlinear stimulated Brillouin scattering process. The double-pass Thomson scattering method using the SBS-PCM has demonstrated an increase of the scattered light by a factor of 1.6 compared with the single-pass scattering method in JT-60U. A multipass Thomson scattering method in which the laser beam can be confined between a couple of SBS-PCMs is also proposed. It is estimated that the multipass scattering method generates the scattered light more than several times as large as that of the single-pass scattering method. For the second method, a high-average-power yttrium aluminum garnet (Nd:YAG) laser system has been developed using the SBS-PCM. The SBS-PCM effectively compensated thermal degradation at two amplifier lines, and the average power was increased by a factor of >8 from 45 W (1.5 J, 30 Hz) to 373 W (7.46 J, 50 Hz). A Nd:YAG laser (5 J, 100 Hz) for the edge Thomson scattering in International Thermonuclear Experimental Reactor (ITER) has been designed based on the result
Neutron scattering at structural phase transformations
International Nuclear Information System (INIS)
Plakida, N.M.
1982-01-01
The specific fractures of neutron scattering cross sections on crystal lattices at structural phase transformations are considered in the lecture. The analysis of the elastic and inelastic scattering is carried out at different transformations (ordering type, displacement type incommensurable transformations). The experimental study on some transitions are given as an example, namely, transformation at the Brillouin zone edge in cubic perovskite. RbCaF 3 transformation in a quasiunidimensional ferroelectrics CsH 2 PO 4 and CsD 2 PO 4 , phase transformation into an incommensurable phase in diphenyl
Scattering theory of topological phase transitions
Fulga, Ion Cosma
2013-01-01
This thesis deals with characterizing topological phases as well as the transitions between them, focusing on transport properties and the effects of disorder. In Chapters 2 and 3 we derived scattering matrix expressions for the topological invariants of systems. This approach is oftentimes
Phase sensitive small angle neutron scattering
Brok, Erik; Majkrzak, Charles F.; Krycka, Kathryn
It is a well-known problem that information about the scattered wave is lost in scattering experiments because the measured quantity is the modulus squared of the complex wave function. This ''phase problem'' leads to ambiguity in determining the physical properties of the scattering sample. Small angle neutron scattering (SANS) is a useful technique for determining the structure of biomolecules, in particular proteins that cannot be crystallized and studied with x-ray crystallography. However, because the biomolecules are usually suspended in a liquid the observed scattering is an average of all possible orientations, making it difficult to obtain three dimensional structural information. In a proposed method polarized SANS and magnetic nanoparticle references attached to the sample molecules is used to obtain phase sensitive structural information and simultaneously circumvent the problem of orientational averaging (Majkrzak et al. J. Appl. Cryst. 47, 2014) If realized and perfected the technique is very promising for unambiguous determination of the three dimensional structure of biomolecules. We demonstrate the principles of our method and show the first experimental data obtained on a simple test system consisting of core shell magnetic nanoparticles.
Transient Rayleigh scattering from single semiconductor nanowires
Energy Technology Data Exchange (ETDEWEB)
Montazeri, Mohammad; Jackson, Howard E.; Smith, Leigh M. [Department of Physics, University of Cincinnati, Cincinnati, OH 45221-0011 (United States); Yarrison-Rice, Jan M. [Department of Physics, Miami University, Oxford, OH 45056 (United States); Kang, Jung-Hyun; Gao, Qiang; Tan, Hark Hoe; Jagadish, Chennupati [Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra, ACT 0200 (Australia)
2013-12-04
Transient Rayleigh scattering spectroscopy is a new pump-probe technique to study the dynamics and cooling of photo-excited carriers in single semiconductor nanowires. By studying the evolution of the transient Rayleigh spectrum in time after excitation, one can measure the time evolution of the density and temperature of photo-excited electron-hole plasma (EHP) as they equilibrate with lattice. This provides detailed information of dynamics and cooling of carriers including linear and bimolecular recombination properties, carrier transport characteristics, and the energy-loss rate of hot electron-hole plasma through the emission of LO and acoustic phonons.
Kazantsev, I. G.; Olsen, U. L.; Poulsen, H. F.; Hansen, P. C.
2018-02-01
We investigate the idealized mathematical model of single scatter in PET for a detector system possessing excellent energy resolution. The model has the form of integral transforms estimating the distribution of photons undergoing a single Compton scattering with a certain angle. The total single scatter is interpreted as the volume integral over scatter points that constitute a rotation body with a football shape, while single scattering with a certain angle is evaluated as the surface integral over the boundary of the rotation body. The equations for total and sample single scatter calculations are derived using a single scatter simulation approximation. We show that the three-dimensional slice-by-slice filtered backprojection algorithm is applicable for scatter data inversion provided that the attenuation map is assumed to be constant. The results of the numerical experiments are presented.
Using phase for radar scatterer classification
Moore, Linda J.; Rigling, Brian D.; Penno, Robert P.; Zelnio, Edmund G.
2017-04-01
Traditional synthetic aperture radar (SAR) systems tend to discard phase information of formed complex radar imagery prior to automatic target recognition (ATR). This practice has historically been driven by available hardware storage, processing capabilities, and data link capacity. Recent advances in high performance computing (HPC) have enabled extremely dense storage and processing solutions. Therefore, previous motives for discarding radar phase information in ATR applications have been mitigated. First, we characterize the value of phase in one-dimensional (1-D) radar range profiles with respect to the ability to correctly estimate target features, which are currently employed in ATR algorithms for target discrimination. These features correspond to physical characteristics of targets through radio frequency (RF) scattering phenomenology. Physics-based electromagnetic scattering models developed from the geometrical theory of diffraction are utilized for the information analysis presented here. Information is quantified by the error of target parameter estimates from noisy radar signals when phase is either retained or discarded. Operating conditions (OCs) of signal-tonoise ratio (SNR) and bandwidth are considered. Second, we investigate the value of phase in 1-D radar returns with respect to the ability to correctly classify canonical targets. Classification performance is evaluated via logistic regression for three targets (sphere, plate, tophat). Phase information is demonstrated to improve radar target classification rates, particularly at low SNRs and low bandwidths.
DEFF Research Database (Denmark)
Kazantsev, I.G.; Olsen, Ulrik Lund; Poulsen, Henning Friis
2018-01-01
scatter is interpreted as the volume integral over scatter points that constitute a rotation body with a football shape, while single scattering with a certain angle is evaluated as the surface integral over the boundary of the rotation body. The equations for total and sample single scatter calculations...... are derived using a single scatter simulation approximation. We show that the three-dimensional slice-by-slice filtered backprojection algorithm is applicable for scatter data inversion provided that the attenuation map is assumed to be constant. The results of the numerical experiments are presented....
Expressive Single Scattering for Light Shaft Stylization
Kol, T.R.; Klehm, O.; Seidel, Hans-Peter; Eisemann, E.
2017-01-01
Light scattering in participating media is a natural phenomenon that is increasingly featured in movies and games, as it is visually pleasing and lends realism to a scene. In art, it may further be used to express a certain mood or emphasize objects. Here, artists often rely on stylization when
Compton-scatter tissue densitometry: calculation of single and multiple scatter photon fluences
International Nuclear Information System (INIS)
Battista, J.J.; Bronskill, M.J.
1978-01-01
The accurate measurement of in vivo electron densities by the Compton-scatter method is limited by attenuations and multiple scattering in the patient. Using analytic and Monte Carlo calculation methods, the Clarke tissue density scanner has been modelled for incident monoenergetic photon energies from 300 to 2000 keV and for mean scattering angles of 30 to 130 degrees. For a single detector focussed to a central position in a uniform water phantom (25 x 25 x 25 cm 3 ) it has been demonstrated that: (1) Multiple scatter contamination is an inherent limitation of the Compton-scatter method of densitometry which can be minimised, but not eliminated, by improving the energy resolution of the scattered radiation detector. (2) The choice of the incident photon energy is a compromise between the permissible radiation dose to the patient and the tolerable level of multiple scatter contamination. For a mean scattering angle of 40 degrees, the intrinsic multiple-single scatter ratio decreases from 64 to 35%, and the radiation dose (per measurement) increases from 1.0 to 4.1 rad, as the incident photon energy increases from 300 to 2000 keV. These doses apply to a sampled volume of approximately 0.3 cm 3 and an electron density precision of 0.5%. (3) The forward scatter densitometer configuration is optimum, minimising both the dose and the multiple scatter contamination. For an incident photon energy of 1250 keV, the intrinsic multiple-single scatter ratio reduces from 122 to 27%, and the dose reduces from 14.3 to 1.2 rad, as the mean scattering angle decreases from 130 to 30 degrees. These calculations have been confirmed by experimental measurements. (author)
Single and Multiple Scattering in UWB Bicone Arrays
Directory of Open Access Journals (Sweden)
Raffaele D'Errico
2008-01-01
Full Text Available An analysis of interactions between radiators in a UWB biconical array, drawing attention to single and multiple scatterings, is carried out. The complementarity between electrical coupling and radiation scattering is argued. The point source approximation is discussed and shown to be insufficient. An approximation of radiation scattering based on angular averaging of the scattering coefficient is proposed. This approach yields a reduction of the problem complexity, which is especially interesting in UWB multiple antenna systems, because of the large bandwidth. Multiple scattering between radiators is shown to be a second-order effect. Finally, a time domain approach is used in order to investigate pulse distortion and quantify the exactness of the proposed scattering model.
Integrated Raman and angular scattering of single biological cells
Smith, Zachary J.
2009-12-01
Raman, or inelastic, scattering and angle-resolved elastic scattering are two optical processes that have found wide use in the study of biological systems. Raman scattering quantitatively reports on the chemical composition of a sample by probing molecular vibrations, while elastic scattering reports on the morphology of a sample by detecting structure-induced coherent interference between incident and scattered light. We present the construction of a multimodal microscope platform capable of gathering both elastically and inelastically scattered light from a 38 mum2 region in both epi- and trans-illumination geometries. Simultaneous monitoring of elastic and inelastic scattering from a microscopic region allows noninvasive characterization of a living sample without the need for exogenous dyes or labels. A sample is illuminated either from above or below with a focused 785 nm TEM00 mode laser beam, with elastic and inelastic scattering collected by two separate measurement arms. The measurements may be made either simultaneously, if identical illumination geometries are used, or sequentially, if the two modalities utilize opposing illumination paths. In the inelastic arm, Stokes-shifted light is dispersed by a spectrograph onto a CCD array. In the elastic scattering collection arm, a relay system images the microscope's back aperture onto a CCD detector array to yield an angle-resolved elastic scattering pattern. Post-processing of the inelastic scattering to remove fluorescence signals yields high quality Raman spectra that report on the sample's chemical makeup. Comparison of the elastically scattered pupil images to generalized Lorenz-Mie theory yields estimated size distributions of scatterers within the sample. In this thesis we will present validations of the IRAM instrument through measurements performed on single beads of a few microns in size, as well as on ensembles of sub-micron particles of known size distributions. The benefits and drawbacks of the
Single crystal surface structure by bragg scattering
DEFF Research Database (Denmark)
Nielsen, Mogens
1985-01-01
X-ray diffraction is becoming an important tool in the measurements of surface structures. Single crystalline samples are used as in Low Energy Electron Diffraction (LEED)-studies. The X-ray technique is somewhat more involved due to the need of bright, collimated photon sources, in general...
Analytical Approximations to Seawater Optical Phase Functions of Scattering
National Research Council Canada - National Science Library
Haltrin, Vladimir I
2004-01-01
.... The paper contains data tables showing the following: inherent optical properties and coefficients for 15 Petzold phase functions of light scattering measured off the Southern California coast, San Diego Harbor, and near the Bahama Islands...
Mie scatter corrections in single cell infrared microspectroscopy.
Konevskikh, Tatiana; Lukacs, Rozalia; Blümel, Reinhold; Ponossov, Arkadi; Kohler, Achim
2016-06-23
Strong Mie scattering signatures hamper the chemical interpretation and multivariate analysis of the infrared microscopy spectra of single cells and tissues. During recent years, several numerical Mie scatter correction algorithms for the infrared spectroscopy of single cells have been published. In the paper at hand, we critically reviewed existing algorithms for the correction of Mie scattering and suggest improvements. We developed an iterative algorithm based on Extended Multiplicative Scatter Correction (EMSC), for the retrieval of pure absorbance spectra from highly distorted infrared spectra of single cells. The new algorithm uses the van de Hulst approximation formula for the extinction efficiency employing a complex refractive index. The iterative algorithm involves the establishment of an EMSC meta-model. While existing iterative algorithms for the correction of resonant Mie scattering employ three independent parameters for establishing a meta-model, we could decrease the number of parameters from three to two independent parameters, which reduced the calculation time for the Mie scattering curves for the iterative EMSC meta-model by a factor of 10. Moreover, by employing the Hilbert transform for evaluating the Kramers-Kronig relations based on a FFT algorithm in Matlab, we further improved the speed of the algorithm by a factor of 100. For testing the algorithm we simulate distorted apparent absorbance spectra by utilizing the exact theory for the scattering of infrared light at absorbing spheres, taking into account the high numerical aperture of infrared microscopes employed for the analysis of single cells and tissues. In addition, the algorithm was applied to measured absorbance spectra of single lung cancer cells.
Single particle analysis with a 3600 light scattering photometer
International Nuclear Information System (INIS)
Bartholdi, M.F.
1979-06-01
Light scattering by single spherical homogeneous particles in the diameter range 1 to 20 μm and relative refractive index 1.20 is measured. Particle size of narrowly dispersed populations is determined and a multi-modal dispersion of five components is completely analyzed. A 360 0 light scattering photometer for analysis of single particles has been designed and developed. A fluid stream containing single particles intersects a focused laser beam at the primary focal point of an ellipsoidal reflector ring. The light scattered at angles theta = 2.5 0 to 177.5 0 at phi = 0 0 and 180 0 is reflected onto a circular array of photodiodes. The ellipsoidal reflector is situated in a chamber filled with fluid matching that of the stream to minimize refracting and reflecting interfaces. The detector array consists of 60 photodiodes each subtending 3 0 in scattering angle on 6 0 centers around 360 0 . 32 measurements on individual particles can be acquired at rates of 500 particles per second. The intensity and angular distribution of light scattered by spherical particles are indicative of size and relative refractive index. Calculations, using Lorenz--Mie theory, of differential scattering patterns integrated over angle corresponding to the detector geometry determined the instrument response to particle size. From this the expected resolution and experimental procedures are determined.Ultimately, the photometer will be utilized for identification and discrimination of biological cells based on the sensitivity of light scattering to size, shape, refractive index differences, internal granularity, and other internal morphology. This study has demonstrated the utility of the photometer and indicates potential for application to light scattering studies of biological cells
Phase-function method for Coulomb-distorted nuclear scattering
Energy Technology Data Exchange (ETDEWEB)
Sett, G.C.; Laha, U.; Talukdar, B.
1988-09-21
The phase-function method is very effective in treating quantum mechanical scattering problems for short-range local potentials. We adapt the phase method to deal with Coulomb plus Graz non-local separable potentials and derive a closed-form expression for the scattering phase shift. Our approach to the problem circumvents in a rather natural way the typical difficulties of incorporating the Coulomb interaction in a nuclear phase-shift calculation. We demonstrate the usefulness of our constructed expression by means of a model calculation.
Iftikhar, Mariam; DeAngelo, Bianca; Arzumanov, Grant; Shanley, Patrick; Xu, Zhang; Xu, M.
2011-02-01
We report first a new derivation of the scattering phase theorem and provide, for the first time, the correct relation between the variance of phase gradient and the reduced scattering coefficient. The scattering-phase theorem is then applied to investigate bulk light scattering property from the phase map of thin slices of tissue phantoms measured by a differential phase interference (DIC) microscope using the intensity propagation equation approach. The scattering coefficient, the reduced scattering coefficient, and the anisotropy factor of the sample obtained with this approach is compared to known scattering property of the bulk samples.
Effective single scattering albedo estimation using regional climate model
CSIR Research Space (South Africa)
Tesfaye, M
2011-09-01
Full Text Available In this study, by modifying the optical parameterization of Regional Climate model (RegCM), the authors have computed and compared the Effective Single-Scattering Albedo (ESSA) which is a representative of VIS spectral region. The arid, semi...
On the nucleon–nucleon scattering phase shifts through ...
Indian Academy of Sciences (India)
Abstract. By exploiting the supersymmetry-inspired factorization method through a judicious use of deuteron ground state wave function, higher partial wave nucleon–nucleon potentials, both energy independent and energy dependent, are generated. We adopt the phase function method to deal with the scattering phase ...
On the nucleon–nucleon scattering phase shifts through ...
Indian Academy of Sciences (India)
By exploiting the supersymmetry-inspired factorization method through a judicious use of deuteron ground state wave function, higher partial wave nucleon–nucleon potentials, both energy independent and energy dependent, are generated. We adopt the phase function method to deal with the scattering phase shifts and ...
Single-phase to three-phase power conversion interface
Wu, Jinn-Chang; Wang, Yung-Shan; Jou, Hurng-Liahng; Lu, Wei-Tso
2016-07-01
This study proposes a single-phase to three-phase power conversion interface which converts the power from a single-phase utility to three-phase power for a three-phase load. The proposed single-phase to three-phase power conversion interface comprises a bridge-type switch set, a set of three-phase inductors, a transformer set and a set of three-phase capacitors. A current-mode control controls the switching of bridge-type switch set, to generate a set of nonzero-sequence (NZS) currents and a set of zero-sequence (ZS) currents. The transformer set is used to decouple the NZS currents and the ZS currents. The NZS currents are used to generate a high-quality three-phase voltage that supplies power to a three-phase load. The ZS currents flow to the single-phase utility so that the utility current is sinusoidal and in phase with the utility voltage. Accordingly, only a bridge-type switch set is used in the single-phase to three-phase power conversion interface to simply the power circuit. A prototype is developed and tested to verify the performance of the proposed single-phase to three-phase power conversion interface.
SCAP-82, Single Scattering, Albedo Scattering, Point-Kernel Analysis in Complex Geometry
International Nuclear Information System (INIS)
Disney, R.K.; Vogtman, S.E.
1987-01-01
1 - Description of problem or function: SCAP solves for radiation transport in complex geometries using the single or albedo scatter point kernel method. The program is designed to calculate the neutron or gamma ray radiation level at detector points located within or outside a complex radiation scatter source geometry or a user specified discrete scattering volume. Geometry is describable by zones bounded by intersecting quadratic surfaces within an arbitrary maximum number of boundary surfaces per zone. Anisotropic point sources are describable as pointwise energy dependent distributions of polar angles on a meridian; isotropic point sources may also be specified. The attenuation function for gamma rays is an exponential function on the primary source leg and the scatter leg with a build- up factor approximation to account for multiple scatter on the scat- ter leg. The neutron attenuation function is an exponential function using neutron removal cross sections on the primary source leg and scatter leg. Line or volumetric sources can be represented as a distribution of isotropic point sources, with un-collided line-of-sight attenuation and buildup calculated between each source point and the detector point. 2 - Method of solution: A point kernel method using an anisotropic or isotropic point source representation is used, line-of-sight material attenuation and inverse square spatial attenuation between the source point and scatter points and the scatter points and detector point is employed. A direct summation of individual point source results is obtained. 3 - Restrictions on the complexity of the problem: - The SCAP program is written in complete flexible dimensioning so that no restrictions are imposed on the number of energy groups or geometric zones. The geometric zone description is restricted to zones defined by boundary surfaces defined by the general quadratic equation or one of its degenerate forms. The only restriction in the program is that the total
Vibrating phase echo concept for small-angle inelastic neutron scattering
International Nuclear Information System (INIS)
Michalec, R.
1989-01-01
Small-angle inelastic neutron scattering measurements are based on the vibrating phase echo concept. The double neutron diffraction is carried out by two thin vibrating single crystals, for example Si or Ge. The neutron beam diffracted at the monochromator crystal M is modulated with a frequency 2 Ω, where Ω is the circular frequency of the ultrasonic transducer. The second crystal A (analyser) vibrates at a frequency Ω with a phase shift φ. A neutron spectrometer on the basis of two vibrating single crystals is suitable within the scattering angle range 0.5' ≤ θ ≤ 50' and within the range of magnitude of the scattering vector Q = (2 to 500) x 10 -3 nm -1 . The described equipment covers the Q values of major part of the classical optical spectroscopy as well as Q values of part of the spin echo spectroscopy
Strong paramagnon scattering in single atom Pd contacts
DEFF Research Database (Denmark)
Schendel, V.; Barreteau, Cyrille; Brandbyge, Mads
2017-01-01
Among all transition metals, palladium (Pd) has the highest density of states at the Fermi energy at low temperatures yet does not fulfill the Stoner criterion for ferromagnetism. However, close proximity to magnetism renders it a nearly ferromagnetic metal, which hosts paramagnons, strongly damp...... adatoms locally induce magnetic order, and transport through single cobalt atoms remains unaffected by paramagnon scattering, consistent with theory....... spin fluctuations. Here we compare the total and the differential conductance of monoatomic contacts consisting of single Pd and cobalt (Co) atoms between Pd electrodes. Transport measurements reveal a conductance for Co of 1G(0), while for Pd we obtain 2G(0). The differential conductance of monoatomic...
Nucleon-Nucleon Potentials and Computation of Scattering Phase Shifts
Directory of Open Access Journals (Sweden)
Jhasaketan Bhoi
2015-12-01
Full Text Available By judicious exploitation of supersymmetry formalism of quantum mechanics higher partial wave nucleon-nucleon potentials are generated from its ground state interactions. The nuclear Hulthen potential and the corresponding ground state wave function with the parameters of Arnold and MacKellar are used as the starting point of our calculation. We compute the scattering phase shifts for our constructed potentials through Phase Function Method to examine the merit of our approach to the problem.
Quantum Theory of Reactive Scattering in Phase Space
Goussev, A.; Schubert, R.; Waalkens, H.; Wiggins, S.; Nicolaides, CA; Brandas, E
2010-01-01
We review recent results on quantum reactive scattering from a phase space perspective. The approach uses classical and quantum versions of Poincare-Birkhoff normal form theory and the perspective of dynamical systems theory. Over the past 10 years the classical normal form theory has provided a
Single scattering from nonspherical Chebyshev particles: A compendium of calculations
Wiscombe, W. J.; Mugnai, A.
1986-01-01
A large set of exact calculations of the scattering from a class of nonspherical particles known as Chebyshev particles' has been performed. Phase function and degree of polarization in random orientation, and parallel and perpendicular intensities in fixed orientations, are plotted for a variety of particles shapes and sizes. The intention is to furnish a data base against which both experimental data, and the predictions of approximate methods, can be tested. The calculations are performed with the widely-used Extended Boundary Condition Method. An extensive discussion of this method is given, including much material that is not easily available elsewhere (especially the analysis of its convergence properties). An extensive review is also given of all extant methods for nonspherical scattering calculations, as well as of the available pool of experimental data.
Quantitative and Isolated Measurement of Far-Field Light Scattering by a Single Nanostructure
Kim, Donghyeong; Jeong, Kwang-Yong; Kim, Jinhyung; Ee, Ho-Seok; Kang, Ju-Hyung; Park, Hong-Gyu; Seo, Min-Kyo
2017-11-01
Light scattering by nanostructures has facilitated research on various optical phenomena and applications by interfacing the near fields and free-propagating radiation. However, direct quantitative measurement of far-field scattering by a single nanostructure on the wavelength scale or less is highly challenging. Conventional back-focal-plane imaging covers only a limited solid angle determined by the numerical aperture of the objectives and suffers from optical aberration and distortion. Here, we present a quantitative measurement of the differential far-field scattering cross section of a single nanostructure over the full hemisphere. In goniometer-based far-field scanning with a high signal-to-noise ratio of approximately 27.4 dB, weak scattering signals are efficiently isolated and detected under total-internal-reflection illumination. Systematic measurements reveal that the total and differential scattering cross sections of a Au nanorod are determined by the plasmonic Fabry-Perot resonances and the phase-matching conditions to the free-propagating radiation, respectively. We believe that our angle-resolved far-field measurement scheme provides a way to investigate and evaluate the physical properties and performance of nano-optical materials and phenomena.
Control of Single-Stage Single-Phase PV inverter
DEFF Research Database (Denmark)
Ciobotaru, Mihai; Teodorescu, Remus; Blaabjerg, Frede
2005-01-01
In this paper the issue of control strategies for single-stage photovoltaic (PV) inverter is addressed. Two different current controllers have been implemented and an experimental comparison between them has been made. A complete control structure for the single-phase PV system is also presented...
Supersymmetric quantum mechanics, phase equivalence, and low energy scattering anomalies
International Nuclear Information System (INIS)
Amado, R.D.; Cannata, F.; Dedonder, J.P.
1991-01-01
Supersymmetric quantum mechanics links two Hamiltonians with the same scattering (phase equivalence) but different number of bound states. We examine the Green's functions for these Hamiltonians as a prelude to embedding the two-body dynamics in a many-body system. We study the effect of the elimination of a two-body bound state near zero energy for the Efimov effect and Beg's theorem
Directory of Open Access Journals (Sweden)
Xiang Liu
Full Text Available The crystal structures of two proteins, a putative pyrazinamidase/nicotinamidase from the dental pathogen Streptococcus mutans (SmPncA and the human caspase-6 (Casp6, were solved by de novo arsenic single-wavelength anomalous diffraction (As-SAD phasing method. Arsenic (As, an uncommonly used element in SAD phasing, was covalently introduced into proteins by cacodylic acid, the buffering agent in the crystallization reservoirs. In SmPncA, the only cysteine was bound to dimethylarsinoyl, which is a pentavalent arsenic group (As (V. This arsenic atom and a protein-bound zinc atom both generated anomalous signals. The predominant contribution, however, was from the As anomalous signals, which were sufficient to phase the SmPncA structure alone. In Casp6, four cysteines were found to bind cacodyl, a trivalent arsenic group (As (III, in the presence of the reducing agent, dithiothreitol (DTT, and arsenic atoms were the only anomalous scatterers for SAD phasing. Analyses and discussion of these two As-SAD phasing examples and comparison of As with other traditional heavy atoms that generate anomalous signals, together with a few arsenic-based de novo phasing cases reported previously strongly suggest that As is an ideal anomalous scatterer for SAD phasing in protein crystallography.
Scattering phase functions of horizontally oriented hexagonal ice crystals
International Nuclear Information System (INIS)
Chen Guang; Yang Ping; Kattawar, George W.; Mishchenko, Michael I.
2006-01-01
Finite-difference time domain (FDTD) solutions are first compared with the corresponding T-matrix results for light scattering by circular cylinders with specific orientations. The FDTD method is then utilized to study the scattering properties of horizontally oriented hexagonal ice plates at two wavelengths, 0.55 and 12 μm. The phase functions of horizontally oriented ice plates deviate substantially from their counterparts obtained for randomly oriented particles. Furthermore, we compute the phase functions of horizontally oriented ice crystal columns by using the FDTD method along with two schemes for averaging over the particle orientations. It is shown that the phase functions of hexagonal ice columns with horizontal orientations are not sensitive to the rotation about the principal axes of the particles. Moreover, hexagonal ice crystals and circular cylindrical ice particles have similar optical properties, particularly, at a strongly absorbing wavelength, if the two particle geometries have the same length and aspect ratio defined as the ratio of the radius or semi-width of the cross section of a particle to its length. The phase functions for the two particle geometries are slightly different in the case of weakly absorbing plates with large aspect ratios. However, the solutions for circular cylinders agree well with their counterparts for hexagonal columns
Preparation of single phase molybdenum boride
International Nuclear Information System (INIS)
Camurlu, Hasan Erdem
2011-01-01
Highlights: → Formation of Mo and a mixture of molybdenum boride phases take place in preparation of molybdenum borides. → It is intricate to prepare single phase molybdenum borides. → Formation of single phase MoB from MoO 3 + B 2 O 3 + Mg mixtures has not been reported previously. → Single phase MoB was successfully prepared through a combination of mechanochemical synthesis and annealing process. - Abstract: The formation of MoB through volume combustion synthesis (VCS), and through mechanochemical synthesis (MCS) followed by annealing has been investigated. MoO 3 , B 2 O 3 and Mg were used as reactants while MgO and NaCl were introduced as diluents. Products were leached in dilute HCl solution and were subjected to X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) examinations. Mo was the major phase component in the VCS products under all the experimental conditions. Mo 2 B, MoB, MoB 2 and Mo 2 B 5 were found as minor phases. Products of MCS contained a mixture of Mo 2 B, MoB, MoB 2 and Mo. After annealing the MCS product at 1400 deg. C for 3 h, single phase α-MoB was obtained.
Potenza, M A C; Sabareesh, K P V; Carpineti, M; Alaimo, M D; Giglio, M
2010-11-05
We present a method based on the optical theorem that yields absolute, calibration free estimates of the optical thickness of scattering particles. The thickness is determined from the phase delay of the zero angle scattered wave. It uses a heterodyne scattering scheme operating in the Raman-Nath approximation. The phase is determined by the position of Talbot-like modulations in the two dimensional power spectrum S(qx, qy) of the transmitted beam intensity distribution. The method is quite insensitive to multiple scattering. It is successfully tested to provide quantitative verification of the optical theorem. Exploratory tests on soft matter samples are reported to suggest its wide applicability to turbid samples.
The single-angle neutron scattering facility at Pelindaba
International Nuclear Information System (INIS)
Hofmeyr, C.; Mayer, R.M.; Tillwick, D.L.; Starkey, J.R.
1978-05-01
The small-angle neutron scattering facility at the SAFARI-1 reactor is described in detail, and with reference to theoretical and practical design considerations. Inexpensive copper microwave guides used as a guide-pipe for slow neutrons provided the basis for a useful though comparatively simple facility. The neutron-spectrum characteristics of the final facility in different configurations of the guide-pipe (both S and single-curved) agree wel with expected values based on results obtained with a test facility. The design, construction, installation and alignment of various components of the facility are outlined, as well as intensity optimisation. A general description is given of experimental procedures and data-aquisition electronics for the four-position sample holder and counter array of up to 18 3 He detectors and a beam monitor [af
Coherent anti-Stokes Raman scattering microscopy of single nanodiamonds.
Pope, Iestyn; Payne, Lukas; Zoriniants, George; Thomas, Evan; Williams, Oliver; Watson, Peter; Langbein, Wolfgang; Borri, Paola
2014-11-01
Nanoparticles have attracted enormous attention for biomedical applications as optical labels, drug-delivery vehicles and contrast agents in vivo. In the quest for superior photostability and biocompatibility, nanodiamonds are considered one of the best choices due to their unique structural, chemical, mechanical and optical properties. So far, mainly fluorescent nanodiamonds have been utilized for cell imaging. However, their use is limited by the efficiency and costs in reliably producing fluorescent defect centres with stable optical properties. Here, we show that single non-fluorescing nanodiamonds exhibit strong coherent anti-Stokes Raman scattering (CARS) at the sp(3) vibrational resonance of diamond. Using correlative light and electron microscopy, the relationship between CARS signal strength and nanodiamond size is quantified. The calibrated CARS signal in turn enables the analysis of the number and size of nanodiamonds internalized in living cells in situ, which opens the exciting prospect of following complex cellular trafficking pathways quantitatively.
Mukherjee, Lipi; Zhai, Peng-Wang; Hu, Yongxiang; Winker, David M
2017-05-10
Polarized radiation fields in a turbid medium are influenced by single-scattering properties of scatterers. It is common that media contain two or more types of scatterers, which makes it essential to properly mix single-scattering properties of different types of scatterers in the vector radiative transfer theory. The vector radiative transfer solvers can be divided into two basic categories: the stochastic and deterministic methods. The stochastic method is basically the Monte Carlo method, which can handle scatterers with different scattering properties explicitly. This mixture scheme is called the external mixture scheme in this paper. The deterministic methods, however, can only deal with a single set of scattering properties in the smallest discretized spatial volume. The single-scattering properties of different types of scatterers have to be averaged before they are input to deterministic solvers. This second scheme is called the internal mixture scheme. The equivalence of these two different mixture schemes of scattering properties has not been demonstrated so far. In this paper, polarized radiation fields for several scattering media are solved using the Monte Carlo and successive order of scattering (SOS) methods and scattering media contain two types of scatterers: Rayleigh scatterers (molecules) and Mie scatterers (aerosols). The Monte Carlo and SOS methods employ external and internal mixture schemes of scatterers, respectively. It is found that the percentage differences between radiances solved by these two methods with different mixture schemes are of the order of 0.1%. The differences of Q/I, U/I, and V/I are of the order of 10 -5 ∼10 -4 , where I, Q, U, and V are the Stokes parameters. Therefore, the equivalence between these two mixture schemes is confirmed to the accuracy level of the radiative transfer numerical benchmarks. This result provides important guidelines for many radiative transfer applications that involve the mixture of
Two-phase flow measurement based on oblique laser scattering
Vendruscolo, Tiago P.; Fischer, Robert; Martelli, Cícero; Rodrigues, Rômulo L. P.; Morales, Rigoberto E. M.; da Silva, Marco J.
2015-07-01
Multiphase flow measurements play a crucial role in monitoring productions processes in many industries. To guarantee the safety of processes involving multiphase flows, it is important to detect changes in the flow conditions before they can cause damage, often in fractions of seconds. Here we demonstrate how the scattering pattern of a laser beam passing a two-phase flow under an oblique angle to the flow direction can be used to detect derivations from the desired flow conditions in microseconds. Applying machine-learning techniques to signals obtained from three photo-detectors we achieve a compact, versatile, low-cost sensor design for safety applications.
Scattering of a vortex pair by a single quantum vortex in a Bose–Einstein condensate
Energy Technology Data Exchange (ETDEWEB)
Smirnov, L. A., E-mail: smirnov-lev@allp.sci-nnov.ru; Smirnov, A. I., E-mail: smirnov@appl.sci-nnov.ru; Mironov, V. A. [Russian Academy of Sciences, Institute of Applied Physics (Russian Federation)
2016-01-15
We analyze the scattering of vortex pairs (the particular case of 2D dark solitons) by a single quantum vortex in a Bose–Einstein condensate with repulsive interaction between atoms. For this purpose, an asymptotic theory describing the dynamics of such 2D soliton-like formations in an arbitrary smoothly nonuniform flow of a ultracold Bose gas is developed. Disregarding the radiation loss associated with acoustic wave emission, we demonstrate that vortex–antivortex pairs can be put in correspondence with quasiparticles, and their behavior can be described by canonical Hamilton equations. For these equations, we determine the integrals of motion that can be used to classify various regimes of scattering of vortex pairs by a single quantum vortex. Theoretical constructions are confirmed by numerical calculations performed directly in terms of the Gross–Pitaevskii equation. We propose a method for estimating the radiation loss in a collision of a soliton-like formation with a phase singularity. It is shown by direct numerical simulation that under certain conditions, the interaction of vortex pairs with a core of a single quantum vortex is accompanied by quite intense acoustic wave emission; as a result, the conditions for applicability of the asymptotic theory developed here are violated. In particular, it is visually demonstrated by a specific example how radiation losses lead to a transformation of a vortex–antivortex pair into a vortex-free 2D dark soliton (i.e., to the annihilation of phase singularities).
DEFF Research Database (Denmark)
Schleger, P.; Casalta, H.; Hadfield, R.
1995-01-01
We present measurements of Ortho-III phase correlations in an untwinned single crystal of YBa2Cu3O6.77 by neutron scattering and the novel method of hard (95 keV) X-ray scattering. The Ortho-III ordering is essentially two-dimensional, exhibiting Lorentzian peak shapes in the a-b plane. At room...
Czech Academy of Sciences Publication Activity Database
Artemyeva, Z.; Žigová, Anna; Kirillova, N.; Šťastný, Martin; Holubík, O.; Podrázský, V.
2017-01-01
Roč. 63, č. 13 (2017), s. 1838-1851 ISSN 0365-0340 Institutional support: RVO:67985831 Keywords : land use * aggregate stability * organo-clay complexes * dynamic light scattering * phase analysis light scattering * color coordinates Subject RIV: DF - Soil Science OBOR OECD: Soil science Impact factor: 2.137, year: 2016
On Spectral Invariance of Single Scattering Albedo for Weakly Absorbing Wavelengths
Marshak, Alexander
2012-01-01
The single scattering albedo omega (sub 0 lambda) in atmospheric radiative transfer is the ratio of the scattering coefficient to the total extinction coefficient. For cloud water droplets both the scattering and absorption coefficients, thus the single scattering albedo, are functions of wavelength A and droplet size r. In this presentation we will show that for water droplets at weakly absorbing wavelengths, the ratio omega (sub 0 lambda)(r). The slope and intercept of the linear function are wavelength independent and sum to unity. This relationship allows for a representation of any single scattering albedo omega (sub 0 lambda) via one known spectrum omega (sub 0 lambda)(r(sub o)). We will provide a simple physical explanation of the discovered relationship. In addition to water droplets, similar linear relationships were found for the single scattering albedo of non-spherical ice crystals. The single scattering albedo $\\omega _ {0\\lambda }$ in atmospheric radiative transfer is the ratio of the scattering coefficient to the total extinction coefficient. For cloud water droplets both the scattering and absorption coefficients, and thus the single scattering albedo, are functions of wavelength $\\lambda $ and droplet size $r$. We show that for water droplets at weakly absorbing wavelengths, the ratio $\\omega _ {0\\lambda } (r)$/$\\omega _ {0\\lambda } (r_{0})$ of two single scattering albedo spectra for two different droplet sizes is a linear function of $\\omega _{0\\lambda }(r)$. The slope and intercept of the linear function are wavelength independent and sum to unity. This relationship allows for a representation of any single scattering albedo $\\omega_{0\\lambda }(r)$ via one known spectrum $\\omega_{0\\lambda }(r_{0})$. We provide a simple physical explanation of the discovered relationship. Similar linear relationships characterize the single scattering albedo of non-spherical ice crystals.
Single phase induction motor with starting performance
Energy Technology Data Exchange (ETDEWEB)
Popescu, M.; Demeter, E. [Research Institute for Electrical Machines, ICPE-ME, Bucharest (Romania); Navrapescu, V. [University `Politehnica` Bucharest, Electrical Engineering Faculty Splaiul Independentei, Bucharest (Romania)
1997-12-31
The paper presents problems related to a special type of single phase induction motor. The main novelty consists in the use of a conducting (aluminium casted) shell distributed on the periferic region of the rotor. As a result the starting performance, as well as the rated ones, is much improved in comparison with the conventional construction. (orig.) 4 refs.
A Study of Multiple Scattering in BGO and LYSO Single Crystal Scintillators
Directory of Open Access Journals (Sweden)
Kittipong Seingsanoh
2016-08-01
Full Text Available The angular distribution of multiple Compton scatterings from BGO and LYSO single crystal scintillators was studied at various scattering angles. Gamma photons with 662 keV energy, acquired from a 137Cs source, were used. The scattered photons were detected by a 51mm × 51mm NaI(Tl scintillation detector. The overall energy correlated to the total number of scattered incidents was analytically reconstructed. The research found that the multiply scattered incidents had the same energy as received from the singly scattered distribution, as the attribution of multiply scattered incidents near the 90° scattering angle revealed. The research results were in agreement with the theoretical calculations.
Global effects of moon phase on nocturnal acoustic scattering layers
Prihartato, PK
2016-01-18
© Inter-Research 2016. The impact of moon phase on the global nocturnal vertical distribution of acoustic scattering layers (SLs) in the upper 200 m was studied during the Malaspina expedition that circumnavigated the world. We assessed the nocturnal weighted mean depths and the vertical extension of the SL (the range between the upper 25th percentile and lower 75th percentile of the backscatter) and used a generalized additive model to reveal the relationship between the nocturnal vertical distribution of the SL and moon phase, as well as other environmental factors. Moon phase significantly affected the SL distribution on a global scale, in contrast to other factors such as dissolved oxygen, temperature and fluorescence, which each correlated with nocturnal SL distribution during the large geographic coverage. Full moon caused a deepening effect on the nocturnal SL. Contrary to expectations, the shallowest distribution was not observed during the darkest nights (new moon) and there was no difference in vertical distribution between new moon and intermediate moon phases. We conclude that the trend of deepening SL during approximately full moon (bright nights) is a global phenomenon related to anti-predator behavior.
The impact of ice particle roughness on the scattering phase matrix
International Nuclear Information System (INIS)
Baum, Bryan A.; Yang Ping; Hu Yongxiang; Feng Qian
2010-01-01
The goal of this study is to explore the influence of ice particle habit (or shape) and surface roughness on the scattering phase matrix. As an example, reported here are the results for two wavelengths: 0.67 and 1.61 μm. For this effort, a database of single-scattering properties has been computed for a set of habits including hexagonal plates, hollow and solid columns, hollow and solid 3D bullet rosettes, droxtals, aggregates of solid columns, and aggregates of plates. The database provides properties for each of the habits at 101 wavelengths between 0.45 and 2.24 μm for smooth, moderately roughened, and severely roughened particles. At each wavelength, the scattering properties are provided at 233 discrete particle diameters ranging from 2 to 10,000 μm. A single particle size distribution from a very cold ice cloud sampled during the CRYSTAL-FACE field campaign (T cld =-76 o C) is used to illustrate the influence of habit and roughness on the phase matrix. In all, four different habit mixtures are evaluated. The nonzero elements of the phase matrix are shown to be quite sensitive to the assumed habit, particularly in the case of -P 12 /P 11 that is associated with the degree of linear polarization of scattered radiation. Surface roughness is shown to smooth out maxima in the scattering phase function and in the other elements of the phase matrix, consistent with other studies. To compare with the theoretical simulations of the phase matrix for smooth and roughened particles, a full year of cloud-aerosol lidar with orthogonal polarization (CALIOP) data from 2008 is analyzed to provide global statistics on the values of P 11 and P 22 /P 11 in the backscattering direction. In a comparison of two of the habit mixtures (one used for MODIS Collection 5 and another that incorporates new habits including hollow bullet rosettes and aggregates of plates) with the CALIOP data, the values for P 11 are higher regardless of the degree of particle surface roughness, and the
Control of Single-Stage Single-Phase PV inverter
DEFF Research Database (Denmark)
Ciobotaru, Mihai; Teodorescu, Remus; Blaabjerg, Frede
2005-01-01
In this paper the issue of control strategies for single-stage photovoltaic (PV) inverter is addressed. Two different current controllers have been implemented and an experimental comparison between them has been made. A complete control structure for the single-phase PV system is also presented......-forward; - and the grid current controller implemented in two different ways, using the classical proportional integral (PI) and the novel proportional resonant (PR) controllers. The control strategy was tested experimentally on 1.5 kW PV inverter........ The main elements of the PV control structure are: - a maximum power point tracker (MPPT) algorithm using the incremental conductance method; - a synchronization method using the phase-locked-loop (PLL), based on delay; - the input power control using the dc voltage controller and power feed...
Zhang, Hui; Li, Zhifang; Li, Hui
2012-12-01
In order to study scattering properties of normal and cancerous tissues from human stomach, we collect images for human gastric specimens by using phase-contrast microscope. The images were processed by the way of mathematics morphology. The equivalent particle size distribution of tissues can be obtained. Combining with Mie scattering theory, the scattering properties of tissues can be calculated. Assume scattering of light in biological tissue can be seen as separate scattering events by different particles, total scattering properties can be equivalent to as scattering sum of particles with different diameters. The results suggest that scattering coefficient of the cancerous tissue is significantly higher than that of normal tissue. The scattering phase function is different especially in the backscattering area. Those are significant clinical benefits to diagnosis cancerous tissue
Mao, Aiqin; Jin, Xia; Gu, Xiaolong; Wei, Xiaoqing; Yang, Guojing
2012-08-01
Single-crystal silver (Ag) nanocubes have been synthesized by a rapid and green method at room temperature by adding sodium hydroxide solution to the mixed solutions of silver nitrate, glucose and polyvinylpyrrolidone (PVP). The X-ray diffraction (XRD), ultraviolet-visible (UV-visible) and transmission electron microscopy (TEM) were used to characterize the phase composition and morphology. The results showed that the as-prepared particles were single-crystal Ag nanocubes with edge lengths of around 77 nm and a growing direction along {1 0 0} facets. As substrates for surface-enhanced Raman scattering (SERS) experiment on crystal violet (CV), the SERS enhancement factor of the as-prepared Ag nanocubes were measured to be 5.5 × 104, indicating potential applications in chemical and biological analysis.
Analyses of the energy-dependent single separable potential models for the NN scattering
International Nuclear Information System (INIS)
Ahmad, S.S.; Beghi, L.
1981-08-01
Starting from a systematic study of the salient features regarding the quantum-mechanical two-particle scattering off an energy-dependent (ED) single separable potential and its connection with the rank-2 energy-independent (EI) separable potential in the T-(K-) amplitude formulation, the present status of the ED single separable potential models due to Tabakin (M1), Garcilazo (M2) and Ahmad (M3) has been discussed. It turned out that the incorporation of a self-consistent optimization procedure improves considerably the results of the 1 S 0 and 3 S 1 scattering phase shifts for the models (M2) and (M3) up to the CM wave number q=2.5 fm -1 , although the extrapolation of the results up to q=10 fm -1 reveals that the two models follow the typical behaviour of the well-known super-soft core potentials. It has been found that a variant of (M3) - i.e. (M4) involving one more parameter - gives the phase shifts results which are generally in excellent agreement with the data up to q=2.5 fm -1 and the extrapolation of the results for the 1 S 0 case in the higher wave number range not only follows the corresponding data qualitatively but also reflects a behaviour similar to the Reid soft core and Hamada-Johnston potentials together with a good agreement with the recent [4/3] Pade fits. A brief discussion regarding the features resulting from the variations in the ED parts of all the four models under consideration and their correlations with the inverse scattering theory methodology concludes the paper. (author)
Epi-detection of vibrational phase contrast coherent anti-Stokes Raman scattering
Garbacik, E.T.; Korterik, Jeroen P.; Otto, Cornelis; Herek, Jennifer Lynn; Offerhaus, Herman L.
2014-01-01
We demonstrate a system for the phase-resolved epi-detection of coherent anti-Stokes Raman scattering (CARS) signals in highly scattering and/or thick samples. With this setup, we measure the complex vibrational responses of multiple components in a thick, highly-scattering pharmaceutical tablet in
Probing the phase of the elastic pp scattering amplitude with vortex proton beams
Energy Technology Data Exchange (ETDEWEB)
Ivanov, I. P. [IFPA, Universite de Liege, Allee du 6 Aout 17, batiment B5a, 4000 Liege, Belgium Sobolev Institute of Mathematics, Koptyug avenue 4, 630090, Novosibirsk (Russian Federation)
2013-04-15
We show that colliding vortex proton beams instead of (approximate) plane waves can lead to a direct measurement of how the overall phase of the scattering amplitude changes with the scattering angle. In elastic pp scattering, this will open a novel way to measure the parameter {rho}(t) and probe the real part of the Pomeron.
International Nuclear Information System (INIS)
Haldipur, P.; Margetan, F. J.; Thompson, R. B.
2006-01-01
Single-crystal elastic stiffness constants are important input parameters for many calculations in material science. There are well established methods to measure these constants using single-crystal specimens, but such specimens are not always readily available. The ultrasonic properties of metal polycrystals, such as velocity, attenuation, and backscattered grain noise characteristics, depend in part on the single-crystal elastic constants. In this work we consider the estimation of elastic constants from UT measurements and grain-sizing data. We confine ourselves to a class of particularly simple polycrystalline microstructures, found in some jet-engine Nickel alloys, which are single-phase, cubic, equiaxed, and untextured. In past work we described a method to estimate the single-crystal elastic constants from measured ultrasonic velocity and attenuation data accompanied by metallographic analysis of grain size. However, that methodology assumes that all attenuation is due to grain scattering, and thus is not valid if appreciable absorption is present. In this work we describe an alternative approach which uses backscattered grain noise data in place of attenuation data. Efforts to validate the method using a pure copper specimen are discussed, and new results for two jet-engine Nickel alloys are presented
Phase variation of nucleon-nucleon amplitude for proton-12C elastic scattering
International Nuclear Information System (INIS)
Deng Yibing; Wang Shilai; Yin Gaofang
2006-01-01
Franco and Yin studied for α- 4 He, 3 He, 2 He, 1 He elastic-scattering by using the phase of the nucleon-nucleon elastic-scattering amplitude varies with momentum transfer in the framework of Glauber multiple scattering theory at intermediate energy. The phase variation leads to large changes in the differential cross sections, and brings the Glauber theory into agreement with experimental data. Later Lombard and Maillet is based on the suggestion by Franco and Yin studied for the p- 4 He elastic-scattering in the framework of Glauber theory, and found this phase to be actually important for the description of spin observables. Recently Wang Shilai and Deng Yibing et al studied for the p- 4 He elastic-scattering in the framework of KMT multiple scattering theory at intermediate energy, and found this phase lead to differential cross sections and polarization, which are in better agreement with experimental data. This paper is based on the suggestion by Franco and Yin that the phase of the nucleon-nucleon scattering amplitude should vary with momentum transfer. The proton elastic scattering on 12 C is studied in the KMT multiple scattering theory with microscopic momentum space first term optical potential. The Coulomb interactions are taken into account in our calculation. The theoretical calculation results show that the phase leads to differential cross section and polarization are in better agreement with experimental data. In conclusion this phase is actually important in the framework of KMT theory. (authors)
Decoupling single nanowire mobilities limited by surface scattering and bulk impurity scattering
International Nuclear Information System (INIS)
Khanal, D. R.; Levander, A. X.; Wu, J.; Yu, K. M.; Liliental-Weber, Z.; Walukiewicz, W.; Grandal, J.; Sanchez-Garcia, M. A.; Calleja, E.
2011-01-01
We demonstrate the isolation of two free carrier scattering mechanisms as a function of radial band bending in InN nanowires via universal mobility analysis, where effective carrier mobility is measured as a function of effective electric field in a nanowire field-effect transistor. Our results show that Coulomb scattering limits effective mobility at most effective fields, while surface roughness scattering only limits mobility under very high internal electric fields. High-energy α particle irradiation is used to vary the ionized donor concentration, and the observed decrease in mobility and increase in donor concentration are compared to Hall effect results of high-quality InN thin films. Our results show that for nanowires with relatively high doping and large diameters, controlling Coulomb scattering from ionized dopants should be given precedence over surface engineering when seeking to maximize nanowire mobility.
Single perturbative splitting diagrams in double parton scattering
Gaunt, Jonathan R.
2013-01-01
We present a detailed study of a specific class of graph that can potentially contribute to the proton-proton double parton scattering (DPS) cross section. These are the `2v1' or `single perturbative splitting' graphs, in which two `nonperturbatively generated' ladders interact with two ladders that have been generated via a perturbative 1 → 2 branching process. Using a detailed calculation, we confirm the result written down originally by Ryskin and Snigirev — namely, that the 2v1 graphs in which the two nonperturbatively generated ladders do not interact with one another do contribute to the leading order proton-proton DPS cross section, albeit with a different geometrical prefactor to the one that applies to the `2v2'/`zero perturbative splitting' graphs. We then show that 2v1 graphs in which the `nonperturbatively generated' ladders exchange partons with one another also contribute to the leading order proton-proton DPS cross section, provided that this `crosstalk' occurs at a lower scale than the 1 → 2 branching on the other side of the graph. Due to the preference in the 2v1 graphs for the x value at which the branching occurs, and crosstalk ceases, to be very much larger than the x values at the hard scale, the effect of crosstalk interactions is likely to be a decrease in the 2v1 cross section except at exceedingly small x values (≲ 10-6). At moderate x values ≃ 10-3 -10-2, the x value at the splitting is in the region ≃ 10-1 where PDFs do not change much with scale, and the effect of crosstalk interactions is likely to be small. We give an explicit formula for the contribution from the 2v1 graphs to the DPS cross section, and combine this with a suggestion that we made in a previous publication, that the `double perturbative splitting'/`1v1' graphs should be completely removed from the DPS cross section, to obtain a formula for the DPS cross section. It is pointed out that there are two potentially concerning features in this equation, that
Li, Zhifang; Li, Hui; Zhang, Hui; Lin, Xiaona; Chen, Wei R.
2013-04-01
We combine morphological granulometry with Mie theory in order to analyze phase contrast images of biomedical tissue for cancer diagnosis. This method correlates microscopic phase distributions of the tissue image and macroscopic optical scattering properties of the tissue. Our results show that the particle size density distribution can be used to quantitatively identify morphological changes of cancerous stomach tissues. Our method can distinguish normal tissue from cancerous tissues, using the significant differences in scattering coefficient, reduced scattering coefficient and phase function. Therefore, this method can provide not only quantitative information for the diagnosis of cancer, but also accurate optical scattering parameters for photothermal therapy for cancer.
Angular-dependent light scattering from cancer cells in different phases of the cell cycle.
Lin, Xiaogang; Wan, Nan; Weng, Lingdong; Zhou, Yong
2017-10-10
Cancer cells in different phases of the cell cycle result in significant differences in light scattering properties. In order to harvest cancer cells in particular phases of the cell cycle, we cultured cancer cells through the process of synchronization. Flow cytometric analysis was applied to check the results of cell synchronization and prepare for light scattering measurements. Angular-dependent light scattering measurements of cancer cells arrested in the G1, S, and G2 phases have been performed. Based on integral calculations for scattering intensities from 5° to 10° and from 110° to 150°, conclusions have been reached. Clearly, the sizes of the cancer cells in different phases of the cell cycle dominated the forward scatter. Accompanying the increase of cell size with the progression of the cell cycle, the forward scattering intensity also increased. Meanwhile, the DNA content of cancer cells in every phase of the cell cycle is responsible for light scattering at large scatter angles. The higher the DNA content of cancer cells was, the greater the positive effect on the high-scattering intensity. As expected, understanding the relationships between the light scattering from cancer cells and cell cycles will aid in the development of cancer diagnoses. Also, it may assist in the guidance of antineoplastic drugs clinically.
Single-Receiver GPS Phase Bias Resolution
Bertiger, William I.; Haines, Bruce J.; Weiss, Jan P.; Harvey, Nathaniel E.
2010-01-01
Existing software has been modified to yield the benefits of integer fixed double-differenced GPS-phased ambiguities when processing data from a single GPS receiver with no access to any other GPS receiver data. When the double-differenced combination of phase biases can be fixed reliably, a significant improvement in solution accuracy is obtained. This innovation uses a large global set of GPS receivers (40 to 80 receivers) to solve for the GPS satellite orbits and clocks (along with any other parameters). In this process, integer ambiguities are fixed and information on the ambiguity constraints is saved. For each GPS transmitter/receiver pair, the process saves the arc start and stop times, the wide-lane average value for the arc, the standard deviation of the wide lane, and the dual-frequency phase bias after bias fixing for the arc. The second step of the process uses the orbit and clock information, the bias information from the global solution, and only data from the single receiver to resolve double-differenced phase combinations. It is called "resolved" instead of "fixed" because constraints are introduced into the problem with a finite data weight to better account for possible errors. A receiver in orbit has much shorter continuous passes of data than a receiver fixed to the Earth. The method has parameters to account for this. In particular, differences in drifting wide-lane values must be handled differently. The first step of the process is automated, using two JPL software sets, Longarc and Gipsy-Oasis. The resulting orbit/clock and bias information files are posted on anonymous ftp for use by any licensed Gipsy-Oasis user. The second step is implemented in the Gipsy-Oasis executable, gd2p.pl, which automates the entire process, including fetching the information from anonymous ftp
Directory of Open Access Journals (Sweden)
Guennadi Saiko
2014-01-01
Full Text Available Various scenarios of light propagation paths in turbid media (single backward scattering, multiple backward scattering, banana shape are discussed and their contributions to reflectance spectra are estimated. It has been found that a single backward or multiple forward scattering quasi-1D paths can be the major contributors to reflected spectra in wide area illumination scenario. Such a single backward scattering (SBS approximation allows developing of an analytical approach which can take into account refractive index mismatched boundary conditions and multilayer geometry and can be used for real-time spectral processing. The SBS approach can be potentially applied for the distances between the transport and reduced scattering domains. Its validation versus the Kubelka-Munk model, path integrals, and diffusion approximation of the radiation transport theory is discussed.
An algorithm to determine backscattering ratio and single scattering albedo
Digital Repository Service at National Institute of Oceanography (India)
Suresh, T.; Desa, E.; Matondkar, S.G.P.; Mascarenhas, A.A.M.Q.; Nayak, S.R.; Naik, P.
and backscattering coefficients and the remote sensing reflectance are used to obtain a relationship for the backscattering ratio, which is defined as the ratio of the total backscattering to the total scattering in terms of the remote sensing reflectance of two...
Reichardt, J; Hess, M; Macke, A
2000-04-20
Multiple-scattering correction factors for cirrus particle extinction coefficients measured with Raman and high spectral resolution lidars are calculated with a radiative-transfer model. Cirrus particle-ensemble phase functions are computed from single-crystal phase functions derived in a geometrical-optics approximation. Seven crystal types are considered. In cirrus clouds with height-independent particle extinction coefficients the general pattern of the multiple-scattering parameters has a steep onset at cloud base with values of 0.5-0.7 followed by a gradual and monotonic decrease to 0.1-0.2 at cloud top. The larger the scattering particles are, the more gradual is the rate of decrease. Multiple-scattering parameters of complex crystals and of imperfect hexagonal columns and plates can be well approximated by those of projected-area equivalent ice spheres, whereas perfect hexagonal crystals show values as much as 70% higher than those of spheres. The dependencies of the multiple-scattering parameters on cirrus particle spectrum, base height, and geometric depth and on the lidar parameters laser wavelength and receiver field of view, are discussed, and a set of multiple-scattering parameter profiles for the correction of extinction measurements in homogeneous cirrus is provided.
Inverse scattering solution for the spatially heterogeneous compliance of a single fracture
Minato, S.; Ghose, R.
2013-01-01
Characterizing the spatially heterogeneous fracture compliance through use of elastic waves has the potential to illuminate the hydraulic and mechanical properties along a fracture. We formulate the inverse scattering problem to estimate the heterogeneous compliance distribution along a single
Ma, Shufen; Liu, Haiguang
2016-04-01
X-ray free-electron lasers generate intense femtosecond X-ray pulses, so that high-resolution structure determination becomes feasible from noncrystalline samples, such as single particles or single molecules. At the moment, the orientation of sample particles cannot be precisely controlled, and consequently the unknown orientation needs to be recovered using computational algorithms. This delays the model reconstruction until all the scattering patterns have been re-oriented, which often entails a long elapse of time and until the completion of the experiment. The scattering patterns from single particles or multiple particles can be summed to form a virtual powder diffraction pattern, and the low-resolution region, corresponding to the small-angle X-ray scattering (SAXS) regime, can be analysed using existing SAXS methods. This work presents a pipeline that converts single-particle data sets into SAXS data, from which real-time model reconstruction is achieved using the model retrieval approach implemented in the software package SASTBX [Liu, Hexemer & Zwart (2012). J. Appl. Cryst. 45 , 587-593]. To illustrate the applications, two case studies are presented with real experimental data sets collected at the Linac Coherent Light Source.
Single-site Green function of the Dirac equation for full-potential electron scattering
Energy Technology Data Exchange (ETDEWEB)
Kordt, Pascal
2012-05-30
I present an elaborated analytical examination of the Green function of an electron scattered at a single-site potential, for both the Schroedinger and the Dirac equation, followed by an efficient numerical solution, in both cases for potentials of arbitrary shape without an atomic sphere approximation. A numerically stable way to calculate the corresponding regular and irregular wave functions and the Green function is via the angular Lippmann-Schwinger integral equations. These are solved based on an expansion in Chebyshev polynomials and their recursion relations, allowing to rewrite the Lippmann-Schwinger equations into a system of algebraic linear equations. Gonzales et al. developed this method for the Schroedinger equation, where it gives a much higher accuracy compared to previous perturbation methods, with only modest increase in computational effort. In order to apply it to the Dirac equation, I developed relativistic Lippmann-Schwinger equations, based on a decomposition of the potential matrix into spin spherical harmonics, exploiting certain properties of this matrix. The resulting method was embedded into a Korringa-Kohn-Rostoker code for density functional calculations. As an example, the method is applied by calculating phase shifts and the Mott scattering of a tungsten impurity. (orig.)
International Nuclear Information System (INIS)
Yang, J.; Kuikka, J.T.; Vanninen, E.; Laensimies, E.; Kauppinen, T.; Patomaeki, L.
1999-01-01
Photon scatter is one of the most important factors degrading the quantitative accuracy of SPECT images. Many scatter correction methods have been proposed. The single isotope method was proposed by us. Aim: We evaluate the scatter correction method of improving the quality of images by acquiring emission and transmission data simultaneously with single isotope scan. Method: To evaluate the proposed scatter correction method, a contrast and linearity phantom was studied. Four female patients with fibromyalgia (FM) syndrome and four with chronic back pain (BP) were imaged. Grey-to-cerebellum (G/C) and grey-to-white matter (G/W) ratios were determined by one skilled operator for 12 regions of interest (ROIs) in each subject. Results: The linearity of activity response was improved after the scatter correction (r=0.999). The y-intercept value of the regression line was 0.036 (p [de
Instability of single-phase natural circulation
International Nuclear Information System (INIS)
Xie Heng; Zhang Jinling; Jia Dounan
1997-01-01
The author has investigated the instability of single-phase flows in natural circulation loops. The momentum equation and energy equation are made dimensionless according to some definitions, and some important dimensionless parameters are gotten. The authors decomposed the mean mass flowrate and temperature into a steady solution and a small disturbance equations. Through solving the disturbance equations, the authors get the neutral stability curves. The authors have studied the effect of the two parameters which represent the ratio of buoyancy force to the friction loss in the loop on the stability of loops. The authors also have studied the effect of the difference of height between the center of heat source and the heat sink on the stability
Foschum, Florian; Kienle, Alwin
2013-08-01
We present simulations and measurements with an optimized goniometer for determination of the scattering phase function of suspended particles. We applied the Monte Carlo method, using a radially layered cylindrical geometry and mismatched boundary conditions, in order to investigate the influence of reflections caused by the interfaces of the glass cuvette and the scatterer concentration on the accurate determination of the scattering phase function. Based on these simulations we built an apparatus which allows direct measurement of the phase function from ϑ=7 deg to ϑ=172 deg without any need for correction algorithms. Goniometric measurements on polystyrene and SiO2 spheres proved this concept. Using the validated goniometer, we measured the phase function of yeast cells, demonstrating the improvement of the new system compared to standard goniometers. Furthermore, the scattering phase function of different fat emulsions, like Intralipid, was determined precisely.
High Efficiency Low Scatter Echelle Grating, Phase I
National Aeronautics and Space Administration — A high efficiency low scatter echelle grating will be developed using a novel technique of multiple diamond shaving cuts. The grating will have mirror surfaces on...
Diffuse Neutron Scattering of the High Temperature Phase of Fe3O4
Siratori , K.; Ishii , Y.; Morii , Y.; Funahashi , S.; Yanase , A.
1997-01-01
Diffuse neutron scattering is observed for the high temperature phase of magnetite, Fe3O4, in an extended range in the (001) and (011) plane of the Brillouin zone. Contours of scattered intensity shows a characteristic pattern, discs in the (100) plane around the Γ points, spheres around the X points, etc. The intensity of this diffuse scattering increases with decreasing temperature down to the Verwey point and is attributed to the lattice distortion induced by charge fluctuation in the B si...
Equivalent local potentials and phase approach to low-energy scattering parameters
Energy Technology Data Exchange (ETDEWEB)
Jana, A.K.; Nandi, T.K.; Paul, A.K.; Talukdar, B. (Department of Physics, Santiniketan, West Bengal (India))
1994-01-01
It is shown that the use of the McTavish-Kermode-Melhem-type equivalent local potentials linearizes algorithms of the variable-phase approach needed to compute the low-energy scattering parameters. A case study is presented to demonstrate the merit of the linearized equations, with particular emphasis on the relationship between the interpolating scattering length function and potential functions. (Author).
Structure of phase matrices of light scattering particles derived from symmetry considerations
Directory of Open Access Journals (Sweden)
J. W. Hovenier
2011-09-01
Full Text Available Symmetry considerations are used to deduce equations from which the main structure of the phase matrix of one or more light scattering particles is derived for special directions of incident and scattered light. For this purpose we use symmetry relations with a wide range of validity, as well as rotational symmetry about a vertical axis in a three dimensional coordinate system.
Energy Technology Data Exchange (ETDEWEB)
Birkbak, Mie Elholm; Nielsen, Ida Gjerlevsen; Frølich, Simon; Stock, Stuart R.; Kenesei, Peter; Almer, Jonathan D.; Birkedal, Henrik
2017-02-01
Advanced functional materials often contain multiple phases which are (nano)crystalline and/or amorphous. The spatial distribution of these phases and their properties, including nanocrystallite size and shape, often drives material function yet is difficult to obtain with current experimental techniques. This article describes the use of diffraction scattering computed tomography, which maps wide-angle scattering information onto sample space, to address this challenge. The wide-angle scattering signal contains information on both (nano)crystalline and amorphous phases. Rietveld refinement of reconstructed diffraction patterns is employed to determine anisotropic nanocrystal shapes. The background signal from refinements is used to identify contributing amorphous phases through multivariate curve resolution. Thus it is demonstrated that reciprocal space analysis in combination with diffraction scattering computed tomography is a very powerful tool for the complete analysis of complex multiphase materials such as energy devices.
Potenza, Marco; Villa, Stefano; Sanvito, Tiziano; Albani, Samuel; Delmonte, Barbara; Maggi, Valter
2015-04-01
From the point of view of light scattering each particle is characterized by several parameters, the size being by far the most important in determining the amount of radiated power. Nevertheless, composition, internal structure, shape do slightly affect the way light is scattered, and in turn also prevent the possibility to extract the correct size. Recovering the whole information is of paramount difficulty, if not impossibile for single particles. A trade off can be obtained by introducing the optical thickness, i.e. the product of the size and the refractive index, which determines the optical properties. Here we focus at studying the optical thickness of dust particles from the EPICA Dome C ice core. We provide for the first time a direct measurement of dust optical parameters that is the most direct information needed by climate models, and highlight important differences among samples. The SPES method is named after its capability to access both the extinction cross section and the forward scattered field amplitude for each particle. This method is well working with extremely dilute suspensions, such as Antarctic ice core samples. The SPES method is based upon combined and simultaneous measurements of the power reduction of a laser beam in presence of the particle (extinction by definition) and the interference between the intense transmitted beam and the much fainter forward scattered wave (scattering). In such a way it is possible to access both the amplitude and phase of the scattered wave, which means both the real and imaginary parts of the complex field amplitude. This makes the difference with traditional approaches. We show some preliminary results from glacial and interglacial samples from the EPICA ice core and suggest a method to extract information which is important for the light scattering properties of the ensemble of dust particles contained in each sample.
Thurston, George M.
2006-04-01
We have used light scattering, turbidimetry, and thermodynamic analysis to study the phase diagram of concentrated aqueous mixtures of the bovine lens proteins, γB crystallin, and α crystallin. We find that dilute α crystallin raises the phase separation temperature of concentrated γB crystallin, while more concentrated α crystallin suppresses phase separation. Very concentrated α /γB mixtures can reversibly cloud above 37°C, even though γB alone phase separates only below temperatures near 0°C, and α does not phase separate. At the scattering vector magnitude used, high-concentration α /γB mixtures scatter less light than the weighted average of their component α and γB solutions, while low-concentration α /γB mixtures scatter more than such a weighted average. We use a mean-field thermodynamic analysis of such ternary mixtures to show that the observed light scattering and phase boundaries of α and γB crystallin mixtures give evidence for prominent local fluctuations of relative protein composition. In the single phase, these fluctuations scatter comparatively little light, but are associated with enhanced thermodynamic instability. By applying this analysis to the experimental tie lines we estimate the magnitude of the saddlelike component of the free energy near the aqueous-γB critical point.
A small-angle X-ray scattering study of the lyotropic nematic phase of vanadium pentoxide gels
Energy Technology Data Exchange (ETDEWEB)
Davidson, P. [Universite de Paris-Sud, Orsay (France). Lab. de Phys. des Solides; Bourgaux, C.; Sergot, P.; Livage, J.
1997-10-01
Aqueous suspensions of vanadium pentoxide (V{sub 2}O{sub 5}) ribbons, also called Zocher phases, are known to display a lyotropic nematic phase. In this paper, it is shown how the small-angle X-ray scattering (SAXS) technique can provide useful information on the building blocks and their organization in this phase. SAXS experiments were performed either on unoriented samples or on samples aligned by a magnetic field or by shear flow. The scattering is comparable to that of the other classic lyotropic nematic phases displayed by stiff organic rod-like particles such as the tobacco mosaic virus. Scattering studies show that the building blocks have a ribbon shape, that their thickness is 9(1) A and indirectly that their width is several 100 A. Their length is known to be around a few thousand A and therefore could not be measured by SAXS. By following the average distance between the ribbons as a function of concentration, it is shown that the swelling of the phase is one-dimensional at large concentrations and two-dimensional at low concentrations. Finally, estimates of the nematic order parameter of a single domain sample and of samples sheared in a Couette cell have been obtained. (orig.). 24 refs.
Absorption line profiles in a moving atmosphere - A single scattering linear perturbation theory
Hays, P. B.; Abreu, V. J.
1989-01-01
An integral equation is derived which linearly relates Doppler perturbations in the spectrum of atmospheric absorption features to the wind system which creates them. The perturbation theory is developed using a single scattering model, which is validated against a multiple scattering calculation. The nature and basic properties of the kernels in the integral equation are examined. It is concluded that the kernels are well behaved and that wind velocity profiles can be recovered using standard inversion techniques.
Phase function measurements on nonspherical scatterers using a two-axis goniometer.
Forster, Florian Klaus; Kienle, Alwin; Michels, Rene; Hibst, Raimund
2006-01-01
We present a two-axis goniometer for measuring the phase function of scattering media with an angular resolution of about 0.2 deg having 12 decades of dynamic range and covering almost the full solid angle. The setup is evaluated with polystyrene spheres and with perpendicularly and obliquely illuminated thin glass cylinders. The scattering pattern and its intensity distribution are in excellent agreement with analytical theory. A multiple scattering configuration composed of two parallel cylinders is also examined. Finally, the phase function of dentin slabs is measured and its dependence on the dental microstructure is discussed.
Single-shot X-ray phase-contrast imaging using two-dimensional gratings
Energy Technology Data Exchange (ETDEWEB)
Sato, Genta; Itoh, Hidenosuke; Nagai, Kentaro; Nakamura, Takashi; Yamaguchi, Kimiaki; Kondoh, Takeshi; Handa, Soichiro; Ouchi, Chidane; Teshima, Takayuki; Setomoto, Yutaka; Den, Toru [Frontier Research Center, Corporate R and D Headquarters, Canon Inc., 3-30-2 Shimomaruko, Ohta-ku, Tokyo 146-8501 (Japan); Optics Technology Development Center, Corporate R and D Headquarters, Canon Inc., 23-10, Kiyohara-Kogyodanchi, Utsunomiya Tochigi 321-3231 (Japan); Nanotechnology R and D Center, Corporate R and D Headquarters, Canon Inc., 3-30-2 Shimomaruko, Ohta-ku, Tokyo 146-8501 (Japan)
2012-07-31
We developed a two-dimensional gratings-based X-ray interferometer that requires only a single exposure for clinical radiography. The interferometer consisted of a checkerboard phase grating for {pi} phase modulation and a latticed amplitude grating. Using a synchrotron radiation source, the phase grating modulates the X-rays and generates a self-image, transformed to a moire fringe by the amplitude grating. To allow use of a conventional X-ray tube, the latticed source grating was installed downstream from the X-ray tube. Differential phase-contrast and scattering images in two orthogonal directions were obtained by Fourier analysis of the single moire fringe image and an absorption image. Results show that characteristic features of soft tissue in two orthogonal directions were clearly shown in the differential phase-contrast images.
International Nuclear Information System (INIS)
Bates, F.S.; Koehler, W.C.; Wignall, G.D.; Fetters, L.J.
1986-12-01
A well characterized binary mixture of normal (protonated) and perdeuterated monodisperse 1,2 polybutenes has been studied by small-angle neutron scattering (SANS). For scattering wavevectors q greater than the inverse radius-of-gyration R/sub g/ -1 , the SANS intensity is quantitatively predicted by the random phase approximation (RPA) theory of deGennes over all measured values of the segment-segment interaction parameter Chi. In the region (Chi s-Chi)Chi s -1 > 0.5 the interaction parameter determined using the RPA theory for q > R/sub g/ -1 is greater than that calculated from the zero-angle intensity based on an Ornstein-Zernike plot, where Chi s represents the limit of single phase stability. These findings indicate a correlation between the critical fluctuation length ξ and R/sub g/ which is not accounted for by the RPA theory
Single particle analysis with a 360/sup 0/ light scattering photometer
Energy Technology Data Exchange (ETDEWEB)
Bartholdi, M.F.
1979-06-01
Light scattering by single spherical homogeneous particles in the diameter range 1 to 20 ..mu..m and relative refractive index 1.20 is measured. Particle size of narrowly dispersed populations is determined and a multi-modal dispersion of five components is completely analyzed. A 360/sup 0/ light scattering photometer for analysis of single particles has been designed and developed. A fluid stream containing single particles intersects a focused laser beam at the primary focal point of an ellipsoidal reflector ring. The light scattered at angles theta = 2.5/sup 0/ to 177.5/sup 0/ at phi = 0/sup 0/ and 180/sup 0/ is reflected onto a circular array of photodiodes. The ellipsoidal reflector is situated in a chamber filled with fluid matching that of the stream to minimize refracting and reflecting interfaces. The detector array consists of 60 photodiodes each subtending 3/sup 0/ in scattering angle on 6/sup 0/ centers around 360/sup 0/. 32 measurements on individual particles can be acquired at rates of 500 particles per second. The intensity and angular distribution of light scattered by spherical particles are indicative of size and relative refractive index. Calculations, using Lorenz--Mie theory, of differential scattering patterns integrated over angle corresponding to the detector geometry determined the instrument response to particle size. From this the expected resolution and experimental procedures are determined.Ultimately, the photometer will be utilized for identification and discrimination of biological cells based on the sensitivity of light scattering to size, shape, refractive index differences, internal granularity, and other internal morphology. This study has demonstrated the utility of the photometer and indicates potential for application to light scattering studies of biological cells.
Diffuse neutron scattering from an in situ grown α-AgI single crystal
International Nuclear Information System (INIS)
Keen, D.A.; Nield, V.M.; McGreevy, R.L.
1994-01-01
A large single crystal of α-AgI was grown in situ from the melt on the SXD single-crystal neutron time-of-flight Laue diffractometer using a specially designed furnace. A wide range of reciprocal space was accessed with minimal rotation of the arbitrarily aligned sample. Weak rings of diffuse scattering were observed together with strong scattering around some Bragg peaks. The results are discussed with reference to earlier powder diffraction data and indicate significant correlations between the motion of the silver ions and the vibrations of the iodide ions. (orig.)
International Nuclear Information System (INIS)
Lehtinen, Ossi; Geiger, Dorin; Lee, Zhongbo; Whitwick, Michael Brian; Chen, Ming-Wei; Kis, Andras; Kaiser, Ute
2015-01-01
Here, we present a numerical post-processing method for removing the effect of anti-symmetric residual aberrations in high-resolution transmission electron microscopy (HRTEM) images of weakly scattering 2D-objects. The method is based on applying the same aberrations with the opposite phase to the Fourier transform of the recorded image intensity and subsequently inverting the Fourier transform. We present the theoretical justification of the method, and its verification based on simulated images in the case of low-order anti-symmetric aberrations. Ultimately the method is applied to experimental hardware aberration-corrected HRTEM images of single-layer graphene and MoSe 2 resulting in images with strongly reduced residual low-order aberrations, and consequently improved interpretability. Alternatively, this method can be used to estimate by trial and error the residual anti-symmetric aberrations in HRTEM images of weakly scattering objects
Knafo, W; Fak, B; Lapertot, G; Canfield, P C; Flouquet, J
2003-01-01
Inelastic neutron scattering experiments were performed on single crystals of the heavy-fermion compound CeIn sub 3 for temperatures below and above the Neel temperature, T sub N. In the antiferromagnetically ordered phase, well-defined spin-wave excitations with a bandwidth of 2 meV are observed. The spin waves coexist with quasielastic (QE) Kondo-type spin fluctuations and broadened crystal-field (CF) excitations below T sub N. Above T sub N , only the QE and CF excitations persist, with a weak temperature dependence.
Qin, Yi; Sun, Junqiang; Du, Mingdi; Liao, Jianfei
2012-09-01
A variable transmission spectrum single-passband narrowband optical filter is proposed and experimentally demonstrated. It is based on forward stimulated interpolarization scattering (SIPS) in a photonic crystal fiber by applying a differential quadrature phase-shift keying modulation to the pump wave to broaden and shape the SIPS gain spectrum. By choosing the bit rate of the modulation data pattern, a flat-top steep-cutoff optical bandpass filter with a 3 dB bandwidth of 70 MHz and a 10 dB bandwidth of 90 MHz is realized. In addition, a variable narrowband optical notch filter is also realized by attenuation of the pump wave.
Room temperature single-crystal diffuse scattering and ab initio lattice dynamics in CaTiSiO5.
Gutmann, M J; Refson, K; Zimmermann, M V; Swainson, I P; Dabkowski, A; Dabkowska, H
2013-08-07
Single-crystal diffuse scattering data have been collected at room temperature on synthetic titanite using both neutrons and high-energy x-rays. A simple ball-and-springs model reproduces the observed diffuse scattering well, confirming its origin to be primarily due to thermal motion of the atoms. Ab initio phonons are calculated using density-functional perturbation theory and are shown to reproduce the experimental diffuse scattering. The observed diffuse x-ray and neutron scattering patterns are consistent with a summation of mode frequencies and displacement eigenvectors associated with the entire phonon spectrum, rather than with a simple, short-range static displacement. A band gap is observed between 600 and 700 cm(-1) with only two modes crossing this region, both associated with antiferroelectric Ti-O motion along a. One of these modes (of Bu symmetry), displays a large LO-TO mode-splitting (562-701.4 cm(-1)) and has a dominant component coming from Ti-O bond-stretching and, thus, the mode-splitting is related to the polarizability of the Ti-O bonds along the chain direction. Similar mode-splitting is observed in piezo- and ferroelectric materials. The calculated phonon dispersion model may be of use to others in future to understand the phase transition at higher temperatures, as well as in the interpretation of measured phonon dispersion curves.
Comparison of scatter doses from a multislice and a single slice CT scanner
International Nuclear Information System (INIS)
Burrage, J. W.; Causer, D. A.
2006-01-01
During shielding calculations for a new multislice CT (MSCT) scanner it was found that the manufacturer's data indicated significantly higher external scatter doses than would be generated for a single slice CT (SSCT). Even allowing for increased beam width, the manufacturer's data indicated that the scatter dose per scan was higher by a factor of about 3 to 4. The magnitude of the discrepancy was contrary to expectations and also contrary to a statement by the UK ImPACT group, which indicated that when beam width is taken into account, the scatter doses should be similar. The matter was investigated by comparing scatter doses from an SSCT and an MSCT. Scatter measurements were performed at three points using a standard perspex CTDI phantom, and CT dose indices were also measured to compare scanner output. MSCT measurements were performed with a 40 mm wide beam, SSCT measurements with a 10 mm wide beam. A film badge survey was also performed after the installation of the MSCT scanner to assess the adequacy of lead shielding in the room. It was found that the scatter doses from the MSCT were lower than indicated by the manufacturer's data. MSCT scatter doses were approximately 4 times higher than those from the SSCT, consistent with expectations due to beam width differences. The CT dose indices were similar, and the film badge survey indicated that the existing shielding, which had been adequate for the SSCT, was also adequate for the MSCT
Mimicking multichannel scattering with single-channel approaches
Grishkevich, Sergey; Schneider, Philipp-Immanuel; Vanne, Yulian V.; Saenz, Alejandro
2010-02-01
The collision of two atoms is an intrinsic multichannel (MC) problem, as becomes especially obvious in the presence of Feshbach resonances. Due to its complexity, however, single-channel (SC) approximations, which reproduce the long-range behavior of the open channel, are often applied in calculations. In this work the complete MC problem is solved numerically for the magnetic Feshbach resonances (MFRs) in collisions between generic ultracold Li6 and Rb87 atoms in the ground state and in the presence of a static magnetic field B. The obtained MC solutions are used to test various existing as well as presently developed SC approaches. It was found that many aspects even at short internuclear distances are qualitatively well reflected. This can be used to investigate molecular processes in the presence of an external trap or in many-body systems that can be feasibly treated only within the framework of the SC approximation. The applicability of various SC approximations is tested for a transition to the absolute vibrational ground state around an MFR. The conformance of the SC approaches is explained by the two-channel approximation for the MFR.
Mimicking multichannel scattering with single-channel approaches
International Nuclear Information System (INIS)
Grishkevich, Sergey; Schneider, Philipp-Immanuel; Vanne, Yulian V.; Saenz, Alejandro
2010-01-01
The collision of two atoms is an intrinsic multichannel (MC) problem, as becomes especially obvious in the presence of Feshbach resonances. Due to its complexity, however, single-channel (SC) approximations, which reproduce the long-range behavior of the open channel, are often applied in calculations. In this work the complete MC problem is solved numerically for the magnetic Feshbach resonances (MFRs) in collisions between generic ultracold 6 Li and 87 Rb atoms in the ground state and in the presence of a static magnetic field B. The obtained MC solutions are used to test various existing as well as presently developed SC approaches. It was found that many aspects even at short internuclear distances are qualitatively well reflected. This can be used to investigate molecular processes in the presence of an external trap or in many-body systems that can be feasibly treated only within the framework of the SC approximation. The applicability of various SC approximations is tested for a transition to the absolute vibrational ground state around an MFR. The conformance of the SC approaches is explained by the two-channel approximation for the MFR.
Small angle neutron scattering study on a phase separation in a 3-component microemulsion system
DEFF Research Database (Denmark)
Seto, H.; Yokoi, E.; Komura, S.
1993-01-01
observed a small change of the water droplet size approaching a phase separation point. In this work, further small angle neutron scattering results are presented obtained at the new SANS equipment in JAERI. The evidences described above were confirmed and a detailed phase diagram has been obtained...
Effects of nonlinear phase modulation on low-conversion four-wave mixing Bragg scattering
DEFF Research Database (Denmark)
Andersen, Lasse Mejling; McKinstrie, C. J.; Rottwitt, Karsten
We consider the effects of nonlinear phase modulation (NPM) on frequency converseon by Bragg scattering. Previously we found that arbitrary mode reshaping without temporal entanglement (separability) was possible. When NPM is included, the modes are chirped and the separability is no longer compl...... complete. However, the mode phase shifts are reduced by pump pre-chirping.......We consider the effects of nonlinear phase modulation (NPM) on frequency converseon by Bragg scattering. Previously we found that arbitrary mode reshaping without temporal entanglement (separability) was possible. When NPM is included, the modes are chirped and the separability is no longer...
Kuo, K.; Clune, T.; Pearson, C.; Olson, W. S.; Skofronick-Jackson, G.; Gravner, J.; Griffeath, D.
2010-12-01
This study improves upon an earlier, preliminary study using only three size bins based on maximum diameter in which it is found that the single-scattering properties of ensembles of non-spherical precipitation particles can be better characterized by considering the non-convexity of these particles. The difficulty of retrievals involving non-spherical particles stems not only from the fact that these particles are not spherical but also the fact that the shape composition of an ensemble of particles is usually unknown and the possibility of its mixture is infinite. Being able to adequately characterize the single-scattering properties of ensembles involving these non-spherical particles with as few parameters as possible is at the heart of solving this thorny remote sensing problem. Inspired by how well three parameters, i.e. water content, effective radius, and effective variance (or their equivalent), characterize the single-scattering properties of an ensemble of spherical particles of varying sizes, we set out to find additional parameters that generalize these three for ensembles of non-spherical particles. We find that a non-convexity measure appears to be one of these additional parameters. Non-convexity is expressed as a ratio of two effective radii derived from the moments of a given particle size distribution (PSD), each of which is in essence a ratio of ensemble particle volume to area. The effective radius in the numerator (denoted as rA) of the non-convexity ratio is based on the projection area of the particle ensemble whereas the one in the denominator (denoted as rS) is based on the surface area. In the preliminary study with PSDs having only three size bins, it is found that variations in the single-scattering properties, such as the scattering and extinction coefficients, the asymmetry factor, and even the scattering phase function, of a particle ensemble with a specified water content are very limited (practically non-existent), if 1) the habit
Scattering Phase Functions of Constituents of Mineral Dust Aerosols ...
African Journals Online (AJOL)
The results show that there is increasing asymmetry and complexity of the phase functions with increasing radial sizes for each of the selected constituents: Illite, Kaolinite, Montmorillonte, Hematite, Calcite and Quartz. The behaviour of these constituents as observed by their phase functions provide information on the ...
Directory of Open Access Journals (Sweden)
Han Wen
Full Text Available The development of phase contrast methods for diagnostic x-ray imaging is inspired by the potential of seeing the internal structures of the human body without the need to deposit any harmful radiation. An efficient class of x-ray phase contrast imaging and scatter correction methods share the idea of using structured illumination in the form of a periodic fringe pattern created with gratings or grids. They measure the scatter and distortion of the x-ray wavefront through the attenuation and deformation of the fringe pattern via a phase stepping process. Phase stepping describes image acquisition at regular phase intervals by shifting a grating in uniform steps. However, in practical conditions the actual phase intervals can vary from step to step and also spatially. Particularly with the advent of electromagnetic phase stepping without physical movement of a grating, the phase intervals are dependent upon the focal plane of interest. We describe a demodulation algorithm for phase stepping at arbitrary and position-dependent (APD phase intervals without assuming a priori knowledge of the phase steps. The algorithm retrospectively determines the spatial distribution of the phase intervals by a Fourier transform method. With this ability, grating-based x-ray imaging becomes more adaptable and robust for broader applications.
Single-scattering properties of Platonic solids in geometrical-optics regime
International Nuclear Information System (INIS)
Zhang Zhibo; Yang Ping; Kattawar, George W.; Wiscombe, Warren J.
2007-01-01
We investigate the single-scattering properties of the Platonic solids with size parameters in the geometrical-optics regime at wavelengths 0.66 and 11 μm using the geometrical-optics method. The comparisons between the results for the Platonic solids and four types of spherical equivalence show that the equal-surface-area spherical equivalence has the smallest errors in terms of the extinction cross section at both wavelengths. At a wavelength of 0.66 μm, all the spherical equivalences substantially overestimate the asymmetry factors of the Platonic solids; and in the case of strong absorption, they underestimate the single-scattering albedo. The comparisons also show that the spherical equivalences cannot be used to describe the spatial distribution of scattered intensity associated with a prismatic polyhedron
International Nuclear Information System (INIS)
Broome, J.
1965-11-01
The programme SCATTER is a KDF9 programme in the Egtran dialect of Fortran to generate normalized angular distributions for elastically scattered neutrons from data input as the coefficients of a Legendre polynomial series, or from differential cross-section data. Also, differential cross-section data may be analysed to produce Legendre polynomial coefficients. Output on cards punched in the format of the U.K. A. E. A. Nuclear Data Library is optional. (author)
Resonant Rayleigh light scattering of single Au nanoparticles with different sizes and shapes.
Truong, Phuoc Long; Ma, Xingyi; Sim, Sang Jun
2014-02-21
Scientific interest in nanotechnology is driven by the unique and novel properties of nanometer-sized metallic materials such as the strong interaction between the conductive electrons of the nanoparticles and the incident light, caused by localized surface plasmon resonances (LSPRs). In this article, we analysed the relationship of the Rayleigh scattering properties of a single Au nanoparticle with its size, shape, and local dielectric environment. We also provided a detailed study on the refractive index sensitivity of three types of differently shaped Au nanoparticles, which were nanospheres, oval-shaped nanoparticles and nanorods. This study helps one to differentiate the Rayleigh light scattering from individual nanoparticles of different sizes and/or shapes and precisely obtain quantitative data as well as the correlated optical spectra of single gold nanoparticles from the inherently inhomogeneous solution of nanoparticles. These results suggest that the shape, size and aspect ratio of Au nanoparticles are important structural factors in determining the resonant Rayleigh light scattering properties of a single Au nanoparticle such as its spectral peak position, scattering-cross-section and refractive index sensitivity, which gives a handle for the choice of gold nanoparticles for the design and fabrication of single nanosensors.
Lattice and Molecular Vibrations in Single Crystal I2 at 77 K by Inelastic Neutron Scattering
DEFF Research Database (Denmark)
Smith, H. G.; Nielsen, Mourits; Clark, C. B.
1975-01-01
Phonon dispersion curves of single crystal iodine at 77 K have been measured by one-phonon coherent inelastic neutron scattering techniques. The data are analysed in terms of two Buckingham-six intermolecular potentials; one to represent the shortest intermolecular interaction (3.5 Å) and the other...
Kwon Ho Lee; Zhanqing Li; Man Sing Wong; Jinyuan Xin; Wang Yuesi; Wei Min Hao; Fengsheng Zhao
2007-01-01
Single scattering albedo (SSA) governs the strength of aerosols in absorbing solar radiation, but few methods are available to directly measure this important quantity. There currently exist many ground-based measurements of spectral transmittance from which aerosol optical thickness (AOT) are retrieved under clear sky conditions. Reflected radiances at the top of the...
Current Harmonics from Single-Phase Grid-Connected Inverters
DEFF Research Database (Denmark)
Yang, Yongheng; Zhou, Keliang; Blaabjerg, Frede
2016-01-01
factor, or in the low voltage ride through mode with reactive current injection. In this paper, the mechanism of the harmonic current injection from grid-connected single-phase inverter systems is thus explored, and the analysis is conducted on single-phase PV systems. In particular, the analysis......-phase applications as a promising harmonic mitigation solution. Experiments on single-phase grid-connected systems have verified the correctness of the relevant analysis and also the effectiveness of the tailor-made control solution in terms of good harmonic mitigation....
International workshop on phase retrieval and coherent scattering. Coherence 2005
International Nuclear Information System (INIS)
Nugent, K.A.; Fienup, J.R.; Van Dyck, D.; Van Aert, S.; Weitkamp, T.; Diaz, A.; Pfeiffer, F.; Cloetens, P.; Stampanoni, M.; Bunk, O.; David, C.; Bronnikov, A.V.; Shen, Q.; Xiao, X.; Gureyev, T.E.; Nesterets, Ya.I.; Paganin, D.M.; Wilkins, S.W.; Mokso, R.; Cloetens, P.; Ludwig, W.; Hignette, O.; Maire, E.; Faulkner, H.M.L.; Rodenburg, J.M.; Wu, X.; Liu, H.; Grubel, G.; Ludwig, K.F.; Livet, F.; Bley, F.; Simon, J.P.; Caudron, R.; Le Bolloc'h, D.; Moussaid, A.; Gutt, C.; Sprung, M.; Madsen, A.; Tolan, M.; Sinha, S.K.; Scheffold, F.; Schurtenberger, P.; Robert, A.; Madsen, A.; Falus, P.; Borthwick, M.A.; Mochrie, S.G.J.; Livet, F.; Sutton, M.D.; Ehrburger-Dolle, F.; Bley, F.; Geissler, E.; Sikharulidze, I.; Jeu, W.H. de; Lurio, L.B.; Hu, X.; Jiao, X.; Jiang, Z.; Lurio, L.B.; Hu, X.; Jiao, X.; Jiang, Z.; Naryanan, S.; Sinha, S.K.; Lal, J.; Naryanan, S.; Sinha, S.K.; Lal, J.; Robinson, I.K.; Chapman, H.N.; Barty, A.; Beetz, T.; Cui, C.; Hajdu, J.; Hau-Riege, S.P.; He, H.; Stadler, L.M.; Sepiol, B.; Harder, R.; Robinson, I.K.; Zontone, F.; Vogl, G.; Howells, M.; London, R.; Marchesini, S.; Shapiro, D.; Spence, J.C.H.; Weierstall, U.; Eisebitt, S.; Shapiro, D.; Lima, E.; Elser, V.; Howells, M.R.; Huang, X.; Jacobsen, C.; Kirz, J.; Miao, H.; Neiman, A.; Sayre, D.; Thibault, P.; Vartanyants, I.A.; Robinson, I.K.; Onken, J.D.; Pfeifer, M.A.; Williams, G.J.; Pfeiffer, F.; Metzger, H.; Zhong, Z.; Bauer, G.; Nishino, Y.; Miao, J.; Kohmura, Y.; Yamamoto, M.; Takahashi, Y.; Koike, K.; Ebisuzaki, T.; Ishikawa, T.; Spence, J.C.H.; Doak, B.
2005-01-01
The contributions of the participants have been organized into 3 topics: 1) phase retrieval methods, 2) X-ray photon correlation spectroscopy, and 3) coherent diffraction imaging. This document gathers the abstracts of the presentations and of the posters
International workshop on phase retrieval and coherent scattering. Coherence 2005
Energy Technology Data Exchange (ETDEWEB)
Nugent, K.A.; Fienup, J.R.; Van Dyck, D.; Van Aert, S.; Weitkamp, T.; Diaz, A.; Pfeiffer, F.; Cloetens, P.; Stampanoni, M.; Bunk, O.; David, C.; Bronnikov, A.V.; Shen, Q.; Xiao, X.; Gureyev, T.E.; Nesterets, Ya.I.; Paganin, D.M.; Wilkins, S.W.; Mokso, R.; Cloetens, P.; Ludwig, W.; Hignette, O.; Maire, E.; Faulkner, H.M.L.; Rodenburg, J.M.; Wu, X.; Liu, H.; Grubel, G.; Ludwig, K.F.; Livet, F.; Bley, F.; Simon, J.P.; Caudron, R.; Le Bolloc' h, D.; Moussaid, A.; Gutt, C.; Sprung, M.; Madsen, A.; Tolan, M.; Sinha, S.K.; Scheffold, F.; Schurtenberger, P.; Robert, A.; Madsen, A.; Falus, P.; Borthwick, M.A.; Mochrie, S.G.J.; Livet, F.; Sutton, M.D.; Ehrburger-Dolle, F.; Bley, F.; Geissler, E.; Sikharulidze, I.; Jeu, W.H. de; Lurio, L.B.; Hu, X.; Jiao, X.; Jiang, Z.; Lurio, L.B.; Hu, X.; Jiao, X.; Jiang, Z.; Naryanan, S.; Sinha, S.K.; Lal, J.; Naryanan, S.; Sinha, S.K.; Lal, J.; Robinson, I.K.; Chapman, H.N.; Barty, A.; Beetz, T.; Cui, C.; Hajdu, J.; Hau-Riege, S.P.; He, H.; Stadler, L.M.; Sepiol, B.; Harder, R.; Robinson, I.K.; Zontone, F.; Vogl, G.; Howells, M.; London, R.; Marchesini, S.; Shapiro, D.; Spence, J.C.H.; Weierstall, U.; Eisebitt, S.; Shapiro, D.; Lima, E.; Elser, V.; Howells, M.R.; Huang, X.; Jacobsen, C.; Kirz, J.; Miao, H.; Neiman, A.; Sayre, D.; Thibault, P.; Vartanyants, I.A.; Robinson, I.K.; Onken, J.D.; Pfeifer, M.A.; Williams, G.J.; Pfeiffer, F.; Metzger, H.; Zhong, Z.; Bauer, G.; Nishino, Y.; Miao, J.; Kohmura, Y.; Yamamoto, M.; Takahashi, Y.; Koike, K.; Ebisuzaki, T.; Ishikawa, T.; Spence, J.C.H.; Doak, B
2005-07-01
The contributions of the participants have been organized into 3 topics: 1) phase retrieval methods, 2) X-ray photon correlation spectroscopy, and 3) coherent diffraction imaging. This document gathers the abstracts of the presentations and of the posters.
Single-superfield helical-phase inflation
Energy Technology Data Exchange (ETDEWEB)
Ketov, Sergei V., E-mail: ketov@tmu.ac.jp [Department of Physics, Tokyo Metropolitan University, Minami-ohsawa 1-1, Hachioji-shi, Tokyo 192-0397 (Japan); Kavli Institute for the Physics and Mathematics of the Universe (IPMU), The University of Tokyo, Chiba 277-8568 (Japan); Institute of Physics and Technology, Tomsk Polytechnic University, 30 Lenin Ave., Tomsk 634050 (Russian Federation); Terada, Takahiro, E-mail: takahiro@hep-th.phys.s.u-tokyo.ac.jp [Department of Physics, The University of Tokyo, Tokyo 113-0033 (Japan); Deutsches Elektronen-Synchrotron (DESY), 22607 Hamburg (Germany)
2016-01-10
Large-field inflation in supergravity requires the approximate global symmetry needed to protect flatness of the scalar potential. In helical-phase inflation, the U(1) symmetry of the Kähler potential is assumed, the phase part of the complex scalar of a chiral superfield plays the role of inflaton, and the radial part is strongly stabilized. The original model of helical phase inflation, proposed by Li, Li and Nanopoulos (LLN), employs an extra (stabilizer) superfield. We propose a more economical new class of the helical phase inflationary models without a stabilizer superfield. As the specific examples, the quadratic, the natural, and the Starobinsky-type inflationary models are studied in our approach.
Nucleon-alpha particle interactions from inversion of scattering phase shifts
International Nuclear Information System (INIS)
Alexander, N.; Amos, K.; Apagyi, B.; Lun, D.R.
1996-01-01
Scattering amplitudes have been extracted from (elastic scattering) neutron-alpha (n-α) differential cross sections below threshold using the constraint that the scattering function is unitary. Real phase shifts have been obtained therefrom. A modification to the Newton iteration method has been used to solve the nonlinear equation that specifies the phase of the scattering amplitude in terms of the complete (0 to 180 deg) cross section since the condition for a unique and convergent solution by an exact iterated fixed point method, the 'Martin' condition, is not satisfied. The results compare well with those found using standard optical model search procedures. Those optical model phase shifts, from both n - α and p - α (proton-alpha) calculations in which spin-orbit effects were included, were used in the second phase of this study, namely to determine the scattering potentials by inversion of that phase shift data. A modified Newton-Sabatier scheme to solve the inverse scattering problem has been used to obtain inversion potentials (both central and spin-orbit) for nucleon energies in the range 1 to 24 MeV. The inversion interactions differ noticeably from the Woods-Saxon forms used to give the input phase shifts. Not only do those inversion potentials when used in Schroedinger equations reproduce the starting phase shifts but they are also very smooth, decay rapidly, and are as feasible as the optical model potentials of others to be the local form for interactions deduced by folding realistic two-nucleon g matrices with the density matrix elements of the alpha particle. 23 refs., 8 tabs., 9 figs
Small angle neutron scattering form polymer melts: structural investigation and phase behaviour
International Nuclear Information System (INIS)
Ertugrul, O.
2004-01-01
The Small-Angle Neutron Scattering (SANS) techniques have been used to study the structural properties and phase behavior of polymer melts. A model based on Random Phase Approximation (RPA) is proposed to predict the experimental data. By fitting the model to data we could be able to obtain radius of gyration (a measure of size of a polymer) and phase transition for the sample. (author)
Spatial distribution of mineral dust single scattering albedo based on DREAM model
Kuzmanoski, Maja; Ničković, Slobodan; Ilić, Luka
2016-04-01
Mineral dust comprises a significant part of global aerosol burden. There is a large uncertainty in estimating role of dust in Earth's climate system, partly due to poor characterization of its optical properties. Single scattering albedo is one of key optical properties determining radiative effects of dust particles. While it depends on dust particle sizes, it is also strongly influenced by dust mineral composition, particularly the content of light-absorbing iron oxides and the mixing state (external or internal). However, an assumption of uniform dust composition is typically used in models. To better represent single scattering albedo in dust atmospheric models, required to increase accuracy of dust radiative effect estimates, it is necessary to include information on particle mineral content. In this study, we present the spatial distribution of dust single scattering albedo based on the Dust Regional Atmospheric Model (DREAM) with incorporated particle mineral composition. The domain of the model covers Northern Africa, Middle East and the European continent, with horizontal resolution set to 1/5°. It uses eight particle size bins within the 0.1-10 μm radius range. Focusing on dust episode of June 2010, we analyze dust single scattering albedo spatial distribution over the model domain, based on particle sizes and mineral composition from model output; we discuss changes in this optical property after long-range transport. Furthermore, we examine how the AERONET-derived aerosol properties respond to dust mineralogy. Finally we use AERONET data to evaluate model-based single scattering albedo. Acknowledgement We would like to thank the AERONET network and the principal investigators, as well as their staff, for establishing and maintaining the AERONET sites used in this work.
Scattering of atomic and molecular ions from single crystal surfaces of Cu, Ag and Fe
International Nuclear Information System (INIS)
Zoest, J.M. van.
1986-01-01
This thesis deals with analysis of crystal surfaces of Cu, Ag and Fe with Low Energy Ion scattering Spectroscopy (LEIS). Different atomic and molecular ions with fixed energies below 7 keV are scattered by a metal single crystal (with adsorbates). The energy and direction of the scattered particles are analysed for different selected charge states. In that way information can be obtained concerning the composition and atomic and electronic structure of the single crystal surface. Energy spectra contain information on the composition of the surface, while structural atomic information is obtained by direction measurements (photograms). In Ch.1 a description is given of the experimental equipment, in Ch.2 a characterization of the LEIS method. Ch.3 deals with the neutralization of keV-ions in surface scattering. Two different ways of data interpretation are presented. First a model is treated in which the observed directional dependence of neutralization action of the first atom layer of the surface is presented by a laterally varying thickness of the neutralizing layer. Secondly it is shown that the data can be reproduced by a more realistic, physical model based on atomic transition matrix elements. In Ch.4 the low energy hydrogen scattering is described. The study of the dissociation of H 2 + at an Ag surface r0230ted in a model based on electronic dissociation, initialized by electron capture into a repulsive (molecular) state. In Ch.5 finally the method is applied to the investigation of the surface structure of oxidized Fe. (Auth.)
Ultra-small-angle x-ray scattering by single-crystal Al deformed in situ
Long, Gabrielle; Levine, Lyle
1997-03-01
Among the earliest small-angle x-ray scattering and small-angle neutron scattering experiments were attempts to study dislocation structures. These structures have proven to be very difficult to measure because of the intrinsically low contrast of the microstructure, and the requirement that multiple Bragg diffraction be strictly avoided. Thus, many attempts to measure dislocation structures have been compromised by these difficulties. We present results from ultra-small-angle x-ray scattering measurements on single-crystal Al, deformed in situ on beam line X23A3 at the National Synchrotron Light Source. Radiographic images, which are in the O-beam position for diffraction, were taken of the scattering volume. The Al crystal was also rotated to ensure that the scattering data would be accumulated in a region sufficiently distant from accidental Bragg diffractions. Stress-strain data were obtained simultaneously with the x-ray scattering data. We report on the evolution of dislocation structures from 0% strain to 18% strain.
MPC of Single Phase Inverter for PV System
Irtaza M. Syed; Kaamran Raahemifar
2014-01-01
This paper presents a model predictive control (MPC) of a utility interactive (UI) single phase inverter (SPI) for a photovoltaic (PV) system at residential/distribution level. The proposed model uses single-phase phase locked loop (PLL) to synchronize SPI with the grid and performs MPC control in a dq reference frame. SPI model consists of boost converter (BC), maximum power point tracking (MPPT) control, and a full bridge (FB) voltage source inverter (VSI). No PI regula...
Azimuthal and single spin asymmetry in deep-inelasticlepton-nucleon scattering
Energy Technology Data Exchange (ETDEWEB)
Liang, Zuo-tang; Wang, Xin-Nian
2006-09-21
The collinear expansion technique is generalized to thefactorization of unintegrated parton distributions and other higher twistparton correlations from the corresponding collinear hard parts thatinvolve multiple parton final state interaction. Such a generalizedfactorization provides a consistent approach to the calculation ofinclusive and semi-inclusive cross sections of deep-inelasticlepton-nucleon scattering. As an example, the azimuthal asymmetry iscalculated to the order of 1/Q in semi-inclusive deeply inelasticlepton-nucleon scattering with transversely polarized target. Anon-vanishing single-spin asymmetry in the "triggered inclusive process"is predicted to be 1/Q suppressed with a part of the coefficient relatedto a moment of the Sivers function.
International Nuclear Information System (INIS)
Vu, H.X.; Yin, L.; DuBois, D.F.; Bezzerides, B.; Dodd, E.S.
2005-01-01
Simulations are reported of the Thomson scatter spectrum of electrostatic waves (ESWs) excited in single laser hot spots by backward stimulated Raman scattering (BSRS). Under conditions similar those in the recent experiments of Kline et al. [Phys. Rev. Lett. 94, 175003 (2005)], a spectral streak, resulting from the trapping-induced frequency shift of the ESW, is found for high wave-number ESWs, similar to the observations. This shift and parametric frequency matching lead to isolated BSRS pulses. Modes with acoustic dispersion, resulting from the trapping-modified electron velocity distribution, can enhance the frequency range of the streak
Son, Taehwang; Kim, Donghyun
2015-03-01
We present a theoretical approach to single nanoparticle detection using surface plasmon scattering microscopy. Through rigorous coupled wave analysis assuming light incidence on a gold coated BK7 glass substrate under total internal reflection condition for a 200-nm polystyrene as targets attached to the gold film, it was found that surface plasmon polariton induced by incident light on the gold thin film is perturbed. As a result, parabolic waves were observed in the reflection plane. By varying angles of incidence and wavelengths, optimum incident conditions for surface plasmon scattering microscopy were obtained.
Zhu, Liang; Li, Guohua; He, Yonghong; Tan, Hui; Sun, Shuqing
2018-02-01
A highly sensitive homogeneous method for DNA detection has been developed. The system relies on two kinds of gold nanorod (AuNR) probes with complementary DNA sequences to the target DNA. In the presence of the target DNA, two kinds of AuNR probes are assembling into dimers or small aggregates. The target-induced AuNR aggregate has higher scattering intensity than that of a single AuNR because of the plasmonic coupling effect. Dark field microscopy was utilized to image the single particle and measure its scattering intensity. We wrote our own Matlab code and used it to extract the scattering signal of all particles. Difference in distribution of scattering intensity between the single AuNR and its aggregate provides a quantitative basis for the detection of target DNA. A linear dynamic range spanning from 0.1pM to 1nM and a detection limit of ~ 30fM were achieved for the detection of DNA in serum sample. Copyright © 2017 Elsevier B.V. All rights reserved.
Determining Complex Structures using Docking Method with Single Particle Scattering Data
Directory of Open Access Journals (Sweden)
Haiguang Liu
2017-04-01
Full Text Available Protein complexes are critical for many molecular functions. Due to intrinsic flexibility and dynamics of complexes, their structures are more difficult to determine using conventional experimental methods, in contrast to individual subunits. One of the major challenges is the crystallization of protein complexes. Using X-ray free electron lasers (XFELs, it is possible to collect scattering signals from non-crystalline protein complexes, but data interpretation is more difficult because of unknown orientations. Here, we propose a hybrid approach to determine protein complex structures by combining XFEL single particle scattering data with computational docking methods. Using simulations data, we demonstrate that a small set of single particle scattering data collected at random orientations can be used to distinguish the native complex structure from the decoys generated using docking algorithms. The results also indicate that a small set of single particle scattering data is superior to spherically averaged intensity profile in distinguishing complex structures. Given the fact that XFEL experimental data are difficult to acquire and at low abundance, this hybrid approach should find wide applications in data interpretations.
Determining Complex Structures using Docking Method with Single Particle Scattering Data.
Wang, Hongxiao; Liu, Haiguang
2017-01-01
Protein complexes are critical for many molecular functions. Due to intrinsic flexibility and dynamics of complexes, their structures are more difficult to determine using conventional experimental methods, in contrast to individual subunits. One of the major challenges is the crystallization of protein complexes. Using X-ray free electron lasers (XFELs), it is possible to collect scattering signals from non-crystalline protein complexes, but data interpretation is more difficult because of unknown orientations. Here, we propose a hybrid approach to determine protein complex structures by combining XFEL single particle scattering data with computational docking methods. Using simulations data, we demonstrate that a small set of single particle scattering data collected at random orientations can be used to distinguish the native complex structure from the decoys generated using docking algorithms. The results also indicate that a small set of single particle scattering data is superior to spherically averaged intensity profile in distinguishing complex structures. Given the fact that XFEL experimental data are difficult to acquire and at low abundance, this hybrid approach should find wide applications in data interpretations.
On the additivity of scattering phases in collisions of electrons on endohedrals
International Nuclear Information System (INIS)
Amusia, M Ya; Chernysheva, L V
2015-01-01
It is demonstrated that an inner atom, either Ne or Ar, qualitatively affects the electron scattering phases upon an endohedral, in spite of the fact that the fullerene consists of 60 carbon atoms, while the atom staffed inside is only one. Calculations are performed in the one-electron Hartree-Fock (HF) and random phase approximation with exchange (RPAE) for the inner atom while the fullerenes shell is substituted by static potential without and with the polarization potential. The total endohedral scattering phase is a sum of atomic, Ne or Ar, and fullerenes C 60 phases, contrary to the intuitive assumption that the total phases on C 60 and Ne@C 60 or Ar@C 60 has to be the same. (paper)
Frontiers of surface-enhanced Raman scattering single nanoparticles and single cells
Ozaki, Yukihiro; Aroca, Ricardo
2014-01-01
A comprehensive presentation of Surface-Enhanced Raman Scattering (SERS) theory, substrate fabrication, applications of SERS to biosystems, chemical analysis, sensing and fundamental innovation through experimentation. Written by internationally recognized editors and contributors. Relevant to all those within the scientific community dealing with Raman Spectroscopy, i.e. physicists, chemists, biologists, material scientists, physicians and biomedical scientists. SERS applications are widely expanding and the technology is now used in the field of nanotechnologies, applications to biosystems, nonosensors, nanoimaging and nanoscience.
Extracting scattering phase shifts in higher partial waves from lattice QCD calculations
Energy Technology Data Exchange (ETDEWEB)
Luu, Thomas; Savage, Martin J.
2011-06-01
Lüscher’s method is routinely used to determine meson-meson, meson-baryon, and baryon-baryon s-wave scattering amplitudes below inelastic thresholds from lattice QCD calculations—presently at unphysical light-quark masses. In this work we review the formalism and develop the requisite expressions to extract phase shifts describing meson-meson scattering in partial waves with angular momentum l≤6 and l=9. The implications of the underlying cubic symmetry, and strategies for extracting the phase shifts from lattice QCD calculations, are presented, along with a discussion of the signal-to-noise problem that afflicts the higher partial waves.
A Novel Single Phase Hybrid Switched Reluctance Motor Drive System
DEFF Research Database (Denmark)
Liang, Jianing; Xu, Guoqing; Jian, Linni
2011-01-01
phase boost converter is applied to improve the performance of this motor. It is easy to generate a double dclink voltage and dc-link voltage and switch both of them. The voltage of boost capacitor is self balance, so the protective circuit is not need to consider. The fast excitation mode helps hybrid......In this paper, a novel single phase hybrid switched reluctance motor(SRM) drive system is proposed. It integrated a single phase hybrid SRM and a novel single phase boost converter. This motor can reduce the number of phase switch. And the permanent magnet which is used in the motor can improve...... the performance and efficiency of SR motor. However, the inherent characteristic of this motor is that the negative torque is very sensitive with the excitation current near the turn-on angle. The slow excitation current limits the torque generation region and reduces the average torque. Therefore, a novel single...
Imaging through scattering media by Fourier filtering and single-pixel detection
Jauregui-Sánchez, Y.; Clemente, P.; Lancis, J.; Tajahuerce, E.
2018-02-01
We present a novel imaging system that combines the principles of Fourier spatial filtering and single-pixel imaging in order to recover images of an object hidden behind a turbid medium by transillumination. We compare the performance of our single-pixel imaging setup with that of a conventional system. We conclude that the introduction of Fourier gating improves the contrast of images in both cases. Furthermore, we show that the combination of single-pixel imaging and Fourier spatial filtering techniques is particularly well adapted to provide images of objects transmitted through scattering media.
Small-angle neutron-scattering studies on oriented single-crystal superalloys
Gilles, R.; Mukherji, D.; Strunz, P.; Wiedenmann, A.; Wahi, R. P.
A single-crystal nickel-base superalloy SC16, recently developed for blade applications in land-based gas turbines, was investigated using the SANS instrument (V4) at the BERII reactor in HMI Berlin. The two-dimensional scattering patterns were measured as a function of the crystallographic orientation and analysed by comparing with iso-intensity profiles simulated on the base of a microstructural model of the SC16. Sizes, interparticle distances, volume fraction and morphology of precipitates were determined. Depending on the heat treatment conditions different scattering patterns were observed corresponding to different morphologies of γ‧ precipitates. Additionally some samples showed streaks in the two-dimensional scattering patterns, indicating the presence of precipitates other than γ‧. This was also confirmed by TEM, SEM and X-ray diffraction studies.
Polarized Raman scattering study of PSN single crystals and epitaxial thin films
Directory of Open Access Journals (Sweden)
J. Pokorný
2015-06-01
Full Text Available This paper describes a detailed analysis of the dependence of Raman scattering intensity on the polarization of the incident and inelastically scattered light in PbSc0.5Nb0.5O3 (PSN single crystals and epitaxially compressed thin films grown on (100-oriented MgO substrates. It is found that there are significant differences between the properties of the crystals and films, and that these differences can be attributed to the anticipated structural differences between these two forms of the same material. In particular, the scattering characteristics of the oxygen octahedra breathing mode near 810 cm-1 indicate a ferroelectric state for the crystals and a relaxor state for the films, which is consistent with the dielectric behaviors of these materials.
Mie Scattering by a Conducting Sphere Coated Uniaxial Single-Negative Medium
Directory of Open Access Journals (Sweden)
You-Lin Geng
2012-01-01
Full Text Available We propose an accurate analytical method to compute the electromagnetic scattering from three-dimensional (3D conducting sphere coated uniaxial anisotropic single-negative (SNG medium. Based on the spherical vector wave functions (SVWFs in uniaxial anisotropic medium, the electromagnetic field in homogeneous uniaxial SNG medium and free space can be expressed by the SVWFs in uniaxial SNG medium and free space. The continued boundary conditions of electromagnetic fields between the uniaxial SNG medium and free space are applied, and the tangential electrical field is vanished in the surface of conducting sphere, the coefficients of scattering fields in free space can be derived, and then the character of scattering of conducting sphere coated homogeneous uniaxial SNG medium can be obtained. Some numericals are given in the end.
Macco, Bart; Knoops, Harm C M; Kessels, Wilhelmus M M
2015-08-05
Hydrogen-doped indium oxide (In2O3:H) has recently emerged as an enabling transparent conductive oxide for solar cells, in particular for silicon heterojunction solar cells because its high electron mobility (>100 cm(2)/(V s)) allows for a simultaneously high electrical conductivity and optical transparency. Here, we report on high-quality In2O3:H prepared by a low-temperature atomic layer deposition (ALD) process and present insights into the doping mechanism and the electron scattering processes that limit the carrier mobility in such films. The process consists of ALD of amorphous In2O3:H at 100 °C and subsequent solid-phase crystallization at 150-200 °C to obtain large-grained polycrystalline In2O3:H films. The changes in optoelectronic properties upon crystallization have been monitored both electrically by Hall measurements and optically by analysis of the Drude response. After crystallization, an excellent carrier mobility of 128 ± 4 cm(2)/(V s) can be obtained at a carrier density of 1.8 × 10(20) cm(-3), irrespective of the annealing temperature. Temperature-dependent Hall measurements have revealed that electron scattering is dominated by unavoidable phonon and ionized impurity scattering from singly charged H-donors. Extrinsic defect scattering related to material quality such as grain boundary and neutral impurity scattering was found to be negligible in crystallized films indicating that the carrier mobility is maximized. Furthermore, by comparison of the absolute H-concentration and the carrier density in crystallized films, it is deduced that <4% of the incorporated H is an active dopant in crystallized films. Therefore, it can be concluded that inactive H atoms do not (significantly) contribute to defect scattering, which potentially explains why In2O3:H films are capable of achieving a much higher carrier mobility than conventional In2O3:Sn (ITO).
Zhou, L.; Gong, Z. R.; Liu, Y. X.; Sun, C. P.; Nori, F.
2010-03-01
We analyze the coherent transport of a single photon, which propagates in a one-dimensional coupled-resonator waveguide and is scattered by a controllable two-level system located inside one of the resonators of this waveguide. Our approach, which uses discrete coordinates, unifies low and high energy effective theories for single-photon scattering. We show that the controllable two-level system can behave as a quantum switch for the coherent transport of a single photon. This study may inspire new electro-optical single-photon quantum devices. We also suggest an experimental setup based on superconducting transmission line resonators and qubits. References: L. Zhou, Z.R. Gong, Y.X. Liu, C.P. Sun, F. Nori, Controllable scattering of photons inside a one-dimensional resonator waveguide, Phys. Rev. Lett. 101, 100501 (2008). L. Zhou, H. Dong, Y.X. Liu, C.P. Sun, F. Nori, Quantum super-cavity with atomic mirrors, Phys. Rev. A 78, 063827 (2008).
Regeneration of phase unlocked serial multiplexed DPSK signals in a single phase sensitive amplifier
DEFF Research Database (Denmark)
Guan, Pengyu; Da Ros, Francesco; Kjøller, Niels-Kristian
2017-01-01
We demonstrate phase-regeneration of phase unlocked OTDM-DPSK serial signals in a single phase sensitive amplifier through optical cross-phase modulation. The BER of an 8×10 Gbit/s OTDM-DPSK signal is improved by 2 orders of magnitude....
Sizing of single evaporating droplet with Near-Forward Elastic Scattering Spectroscopy
Woźniak, M.; Jakubczyk, D.; Derkachov, G.; Archer, J.
2017-11-01
We have developed an optical setup and related numerical models to study evolution of single evaporating micro-droplets by analysis of their spectral properties. Our approach combines the advantages of the electrodynamic trapping with the broadband spectral analysis with the supercontinuum laser illumination. The elastically scattered light within the spectral range of 500-900 nm is observed by a spectrometer placed at the near-forward scattering angles between 4.3 ° and 16.2 ° and compared with the numerically generated lookup table of the broadband Mie scattering. Our solution has been successfully applied to infer the size evolution of the evaporating droplets of pure liquids (diethylene and ethylene glycol) and suspensions of nanoparticles (silica and gold nanoparticles in diethylene glycol), with maximal accuracy of ± 25 nm. The obtained results have been compared with the previously developed sizing techniques: (i) based on the analysis of the Mie scattering images - the Mie Scattering Lookup Table Method and (ii) the droplet weighting. Our approach provides possibility to handle levitating objects with much larger size range (radius from 0.5 μm to 30 μm) than with the use of optical tweezers (typically radius below 8 μm) and analyse them with much wider spectral range than with commonly used LED sources.
Microwave single-scattering properties of randomly oriented soft-ice hydrometeors
Directory of Open Access Journals (Sweden)
D. Casella
2008-11-01
Full Text Available Large ice hydrometeors are usually present in intense convective clouds and may significantly affect the upwelling radiances that are measured by satellite-borne microwave radiometers – especially, at millimeter-wavelength frequencies. Thus, interpretation of these measurements (e.g., for precipitation retrieval requires knowledge of the single scattering properties of ice particles. On the other hand, shape and internal structure of these particles (especially, the larger ones is very complex and variable, and therefore it is necessary to resort to simplifying assumptions in order to compute their single-scattering parameters.
In this study, we use the discrete dipole approximation (DDA to compute the absorption and scattering efficiencies and the asymmetry factor of two kinds of quasi-spherical and non-homogeneous soft-ice particles in the frequency range 50–183 GHz. Particles of the first kind are modeled as quasi-spherical ice particles having randomly distributed spherical air inclusions. Particles of the second kind are modeled as random aggregates of ice spheres having random radii. In both cases, particle densities and dimensions are coherent with the snow hydrometeor category that is utilized by the University of Wisconsin – Non-hydrostatic Modeling System (UW-NMS cloud-mesoscale model. Then, we compare our single-scattering results for randomly-oriented soft-ice hydrometeors with corresponding ones that make use of: a effective-medium equivalent spheres, b solid-ice equivalent spheres, and c randomly-oriented aggregates of ice cylinders. Finally, we extend to our particles the scattering formulas that have been developed by other authors for randomly-oriented aggregates of ice cylinders.
LENA Conversion Foils Using Single-Layer Graphene, Phase I
National Aeronautics and Space Administration — Our key innovation will be the use of single-layer graphene as LENA conversion foils, with appropriate microgrids and nanogrids to support the foils. Phase I...
High Energy Single Frequency Resonant Amplifier, Phase I
National Aeronautics and Space Administration — This SBIR phase I project proposes a single frequency high energy resonant amplifier for remote sensing. Current state-of-art technologies can not provide all...
Non Invasive Instrumentation For Single Event Effects (NIISEE), Phase I
National Aeronautics and Space Administration — On this Phase 1 project, Adventium will identify and address key hurdles to achieve Radiation Hardening by Software (RHS) for Single Event Effects (SEEs) for modern...
Polarized Raman scattering of epitaxial vanadium dioxide films with low-temperature monoclinic phase
Shibuya, Keisuke; Sawa, Akihito
2017-07-01
A polarized Raman scattering study was carried out on epitaxial VO2 thin films on MgF2(001) and (110) substrates to investigate the Raman symmetry and tensor elements of the phonon modes of the films in a low-temperature monoclinic phase. From the polarization angular dependence of the Raman intensity, we assigned the phonon modes at 137, 194, 310, 340, 499, 612, and 663 cm-1 to Ag symmetry and the phonon modes at 143, 262, 442, 480, 582, and 820 cm-1 to Bg symmetry. The angular-dependence measurements also revealed that two phonon modes with Ag and Bg symmetries are present at about 224 and 393 cm-1, although only a single peak was observed in the Raman spectra at around these wavenumbers. On the basis of the experimental results, we evaluated the Raman tensors of the identified phonon modes. From the Raman tensors, we found that the atomic displacements of the 194 and 340 cm-1 phonon modes are approximately perpendicular and parallel, respectively, to the V-V dimer direction. This is consistent with a previous theoretical prediction, i.e., these modes are attributable to the tilting motion and the stretching vibration of the V-V dimers, respectively.
Effects of nonlinear phase modulation on Bragg scattering in the low-conversion regime
DEFF Research Database (Denmark)
Andersen, Lasse Mejling; Cargill, D. S.; McKinstrie, C. J.
2012-01-01
In this paper, we consider the effects of nonlinear phase modulation on frequency conversion by four-wave mixing (Bragg scattering) in the low-conversion regime. We derive the Green functions for this process using the time-domain collision method, for partial collisions, in which the four fields...
On calculating phase shifts and performing fits to scattering cross sections or transport properties
International Nuclear Information System (INIS)
Hepburn, J.W.; Roy, R.J. Le
1978-01-01
Improved methods of calculating quantum mechanical phase shifts and for performing least-squares fits to scattering cross sections or transport properties, are described. Their use in a five-parameter fit to experimental differential cross sections reduces the computer time by a factor of 4-7. (Auth.)
Energy Technology Data Exchange (ETDEWEB)
Buckman, S.J. [Australian National Univ., Canberra, ACT (Australia). Research School of Physical Sciences; Brunger, M.J. [Flinders Univ. of South Australia, Bedford Park, SA (Australia). School of Physical Sciences
1996-07-01
Electron scattering cross sections (elastic, rotational and vibrational excitation) for a number of atomic and (relatively) single molecular systems are examined. Particular reference is made to the level of agreement which is obtained from the application of the completely different measurement philosophies embodied in `beam` and `swarm` techniques. The range of energies considered is generally restricted to the region below 5 eV. 142 refs., 1 tab., 12 figs.
Small angle neutron scattering study of isolated single wall carbon nano tubes in water
International Nuclear Information System (INIS)
Doe, Chang-Woo; Kim, Tae-Hwan; Choi, Sung-Min; Kline, Steven R.
2007-01-01
As an effort to provide more practical approaches to a wide range of potential applications of carbon nano tubes, we report a new type of noncovalently functionalized isolated single-walled carbon nano tube(SWNT) which is easily dispersible in water by only ten minutes of mild vortex mixing. The structure and quality of dispersion have been investigated using small angle neutron scattering (SANS) technique
Xiao, Yongchuan; Guo, Jing; Wu, Kui; Qu, Pengfei; Qi, Huajuan; Liu, Caixia; Ruan, Shengping; Chen, Weiyou; Dong, Wei
2013-02-11
A single passband microwave photonic filter with ultrawide tunable range based on stimulated Brillouin scattering is theoretically analyzed. Combining the gain and loss spectrums, tuning range with 44GHz is obtained without crosstalk by introducing two pumps. Adding more pumps, Tuning range multiplying with the multiplication factor equaling to the total quantity of pump can be achieved, which has potential application in microwave and millimeter wave wireless communication systems.
International Nuclear Information System (INIS)
Buckman, S.J.; Brunger, M.J.
1996-07-01
Electron scattering cross sections (elastic, rotational and vibrational excitation) for a number of atomic and (relatively) single molecular systems are examined. Particular reference is made to the level of agreement which is obtained from the application of the completely different measurement philosophies embodied in 'beam' and 'swarm' techniques. The range of energies considered is generally restricted to the region below 5 eV. 142 refs., 1 tab., 12 figs
Energy Technology Data Exchange (ETDEWEB)
Yang, J.; Kuikka, J.T.; Vanninen, E.; Laensimies, E. [Kuopio Univ. Hospital (Finland). Dept. of Clinical Physiology and Nuclear Medicine; Kauppinen, T.; Patomaeki, L. [Kuopio Univ. (Finland). Dept. of Applied Physics
1999-05-01
Photon scatter is one of the most important factors degrading the quantitative accuracy of SPECT images. Many scatter correction methods have been proposed. The single isotope method was proposed by us. Aim: We evaluate the scatter correction method of improving the quality of images by acquiring emission and transmission data simultaneously with single isotope scan. Method: To evaluate the proposed scatter correction method, a contrast and linearity phantom was studied. Four female patients with fibromyalgia (FM) syndrome and four with chronic back pain (BP) were imaged. Grey-to-cerebellum (G/C) and grey-to-white matter (G/W) ratios were determined by one skilled operator for 12 regions of interest (ROIs) in each subject. Results: The linearity of activity response was improved after the scatter correction (r=0.999). The y-intercept value of the regression line was 0.036 (p<0.0001) after scatter correction and the slope was 0.954. Pairwise correlation indicated the agreement between nonscatter corrected and scatter corrected images. Reconstructed slices before and after scatter correction demonstrate a good correlation in the quantitative accuracy of radionuclide concentration. G/C values have significant correlation coefficients between original and corrected data. Conclusion: The transaxial images of human brain studies show that the scatter correction using single isotope in simultaneous transmission and emission tomography provides a good scatter compensation. The contrasts were increased on all 12 ROIs. The scatter compensation enhanced details of physiological lesions. (orig.) [Deutsch] Die Photonenstreuung gehoert zu den wichtigsten Faktoren, die die quantitative Genauigkeit von SPECT-Bildern vermindern. Es wurde eine ganze Reihe von Methoden zur Streuungskorrektur vorgeschlagen. Von uns wurde die Einzelisotopen-Methode empfohlen. Ziel: Wir untersuchten die Streuungskorrektur-Methode zur Verbesserung der Bildqualitaet durch simultane Gewinnung von Emissions
Eck, T. F.; Holben, B. N.; Mukelabai, M. M.; Dubovik, O.; Smirnov, A.; Schafer, J. S.; Slutsker, I.
2002-05-01
Monitoring of the optical properties of primarily biomass burning aerosols in Mongu, Zambia was initiated in 1995, when an AERONET sun/sky radiometer site was established at the Mongu airport. For the biomass burning season months (July-November), we present monthly means of aerosol single scattering albedo (SSA), aerosol size distributions, and refractive indices from almucantar sky scan retrievals utilizing the algorithm of Dubovik and King (2000). The monthly mean single scattering albedo at 440 nm in Mongu was found to increase significantly from July (0.845) to October (0.93). The slope of the spectral dependence of aerosol single scattering albedo with wavelength decreased as SSA increased from July to October. However, there was no significant change in particle size in either the dominant accumulation or secondary coarse modes during these months. Similarly, seasonal SSA retrievals for Etosha Pan, Namibia also show increasing values through the burning season in 2000. We also analyze the seasonality of SSA for sites in biomass burning regions of Amazonia. We show maps of satellite detected fire counts which indicate that the regions of primary biomass burning shift significantly from July to October. Possible reasons for the seasonal changes in observed SSA include differences in aging to due transport speed and distance from source regions, differences in biomass fuel types in different regions (fraction of woody biomass versus grasses), and differences in fuel moisture content (October is the beginning of the rainy season on both continents).
Photon Cascade from a Single Crystal Phase Nanowire Quantum Dot
DEFF Research Database (Denmark)
Bouwes Bavinck, Maaike; Jöns, Klaus D; Zieliński, Michal
2016-01-01
We report the first comprehensive experimental and theoretical study of the optical properties of single crystal phase quantum dots in InP nanowires. Crystal phase quantum dots are defined by a transition in the crystallographic lattice between zinc blende and wurtzite segments and therefore offe...
Pitch-angle scattering driven by a single wave in Tokamak plasma
International Nuclear Information System (INIS)
Qiu Yunqing; Xia Mengfen
1988-01-01
The interaction of particles with a single wave in a Tokamak plasma is investigated. It is pointed out that the stochastic pitch-angle scattering across the trapped/passing boundary may be driven by a single wave. The characteristics of such separatrix crossings are discussed. It is also found that the wave-driven separatrix crossings are accompanied by a radial flow of particles, which is composed of a directional flow and a diffusional flow. The resultant pitch-angle and radial fluxes are calculated. (author)
Unconventional phase transitions in a constrained single polymer chain
International Nuclear Information System (INIS)
Klushin, L I; Skvortsov, A M
2011-01-01
Phase transitions were recognized among the most fascinating phenomena in physics. Exactly solved models are especially important in the theory of phase transitions. A number of exactly solved models of phase transitions in a single polymer chain are discussed in this review. These are three models demonstrating the second order phase transitions with some unusual features: two-dimensional model of β-structure formation, the model of coil–globule transition and adsorption of a polymer chain grafted on the solid surface. We also discuss models with first order phase transitions in a single macromolecule which admit not only exact analytical solutions for the partition function with explicit finite-size effects but also the non-equilibrium free energy as a function of the order parameter (Landau function) in closed analytical form. One of them is a model of mechanical desorption of a macromolecule, which demonstrates an unusual first order phase transition with phase coexistence within a single chain. Features of first and second order transitions become mixed here due to phase coexistence which is not accompanied by additional interfacial free energy. Apart from that, there exist several single-chain models belonging to the same class (adsorption of a polymer chain tethered near the solid surface or liquid–liquid interface, and escape transition upon compressing a polymer between small pistons) that represent examples of a highly unconventional first order phase transition with several inter-related unusual features: no simultaneous phase coexistence, and hence no phase boundary, non-concave thermodynamic potential and non-equivalence of conjugate ensembles. An analysis of complex zeros of partition functions upon approaching the thermodynamic limit is presented for models with and without phase coexistence. (topical review)
A simple output voltage control scheme for single phase wavelet ...
African Journals Online (AJOL)
DR OKE
Wavelet based techniques have been extensively used in various power engineering applications. Recently, wavelet has also been proposed to generate switching signal for single-phase pulse-width-modulated (PWM) dc-ac inverter. The main advantage of the wavelet modulated (WM) scheme is that a single synthesis ...
Investigating Structure and Dynamics of Proteins in Amorphous Phases Using Neutron Scattering
Directory of Open Access Journals (Sweden)
Maria Monica Castellanos
Full Text Available In order to increase shelf life and minimize aggregation during storage, many biotherapeutic drugs are formulated and stored as either frozen solutions or lyophilized powders. However, characterizing amorphous solids can be challenging with the commonly available set of biophysical measurements used for proteins in liquid solutions. Therefore, some questions remain regarding the structure of the active pharmaceutical ingredient during freezing and drying of the drug product and the molecular role of excipients. Neutron scattering is a powerful technique to study structure and dynamics of a variety of systems in both solid and liquid phases. Moreover, neutron scattering experiments can generally be correlated with theory and molecular simulations to analyze experimental data. In this article, we focus on the use of neutron techniques to address problems of biotechnological interest. We describe the use of small-angle neutron scattering to study the solution structure of biological molecules and the packing arrangement in amorphous phases, that is, frozen glasses and freeze-dried protein powders. In addition, we discuss the use of neutron spectroscopy to measure the dynamics of glassy systems at different time and length scales. Overall, we expect that the present article will guide and prompt the use of neutron scattering to provide unique insights on many of the outstanding questions in biotechnology. Keywords: Neutron scattering, Protein structure, Protein dynamics, Freeze-dried proteins, Glasses, Frozen protein solutions, Molecular dynamics
Energy Technology Data Exchange (ETDEWEB)
Baba, Justin S [ORNL; John, Dwayne O [ORNL; Koju, Vijay [ORNL
2015-01-01
The propagation of light in turbid media is an active area of research with relevance to numerous investigational fields, e.g., biomedical diagnostics and therapeutics. The statistical random-walk nature of photon propagation through turbid media is ideal for computational based modeling and simulation. Ready access to super computing resources provide a means for attaining brute force solutions to stochastic light-matter interactions entailing scattering by facilitating timely propagation of sufficient (>10million) photons while tracking characteristic parameters based on the incorporated physics of the problem. One such model that works well for isotropic but fails for anisotropic scatter, which is the case for many biomedical sample scattering problems, is the diffusion approximation. In this report, we address this by utilizing Berry phase (BP) evolution as a means for capturing anisotropic scattering characteristics of samples in the preceding depth where the diffusion approximation fails. We extend the polarization sensitive Monte Carlo method of Ramella-Roman, et al.,1 to include the computationally intensive tracking of photon trajectory in addition to polarization state at every scattering event. To speed-up the computations, which entail the appropriate rotations of reference frames, the code was parallelized using OpenMP. The results presented reveal that BP is strongly correlated to the photon penetration depth, thus potentiating the possibility of polarimetric depth resolved characterization of highly scattering samples, e.g., biological tissues.
Phase-predictable tuning of single-frequency optical synthesizers.
Rohde, Felix; Benkler, Erik; Puppe, Thomas; Unterreitmayer, Reinhard; Zach, Armin; Telle, Harald R
2014-07-15
We investigate the tuning behavior of a novel type of single-frequency optical synthesizers by phase comparison of the output signals of two identical devices. We achieve phase-stable and cycle-slip free frequency tuning over 28.1 GHz with a maximum zero-to-peak phase deviation of 62 mrad. In contrast to previous implementations of single-frequency optical synthesizers, no comb line order switching is needed when tuned over more than one comb line spacing range of the employed frequency comb.
Johns, Maureen; Liu, Hanli
2003-07-01
When light interacts with tissue, it can be absorbed, scattered or reflected. Such quantitative information can be used to characterize the optical properties of tissue, differentiate tissue types in vivo, and identify normal versus diseased tissue. The purpose of this research is to develop an algorithm that determines the reduced scattering coefficient (μs") of tissues from a single optical reflectance spectrum with a small source-detector separation. The basic relationship between μs" and optical reflectance was developed using Monte Carlo simulations. This produced an analytical equation containing μs" as a function of reflectance. To experimentally validate this relationship, a 1.3-mm diameter fiber optic probe containing two 400-micron diameter fibers was used to deliver light to and collect light from Intralipid solutions of various concentrations. Simultaneous measurements from optical reflectance and an ISS oximeter were performed to validate the calculated μs" values determined by the reflectance measurement against the 'gold standard" ISS readings. The calculated μs" values deviate from the expected values by approximately -/+ 5% with Intralipid concentrations between 0.5 - 2.5%. The scattering properties within this concentration range are similar to those of in vivo tissues. Additional calculations are performed to determine the scattering properties of rat brain tissues and to discuss accuracy of the algorithm for measured samples with a broad range of the absorption coefficient (μa).
Micromagnetic simulation of magnetic small-angle neutron scattering from two-phase nanocomposites
International Nuclear Information System (INIS)
Michels, Andreas; Erokhin, Sergey; Berkov, Dmitry; Gorn, Nataliya
2014-01-01
The recent development of a micromagnetic simulation methodology—suitable for multiphase magnetic nanocomposites—permits the computation of the magnetic microstructure and of the associated magnetic small-angle neutron scattering (SANS) cross section of these materials. In this review we summarize results on the micromagnetic simulation of magnetic SANS from two-phase nanocomposites. The decisive advantage of this approach resides in the possibility to scrutinize the individual magnetization Fourier contributions to the total magnetic SANS cross section, rather than their sum, which is generally obtained from the experiment. The procedure furnishes unique and fundamental information regarding magnetic neutron scattering from nanomagnets
Micromagnetic simulation of magnetic small-angle neutron scattering from two-phase nanocomposites
Energy Technology Data Exchange (ETDEWEB)
Michels, Andreas, E-mail: andreas.michels@uni.lu [Physics and Materials Science Research Unit, University of Luxembourg, 162A Avenue de la Faïencerie, L-1511 Luxembourg (Luxembourg); Erokhin, Sergey; Berkov, Dmitry; Gorn, Nataliya [INNOVENT Technology Development, Prüssingstraße 27B, D-07745 Jena (Germany)
2014-01-15
The recent development of a micromagnetic simulation methodology—suitable for multiphase magnetic nanocomposites—permits the computation of the magnetic microstructure and of the associated magnetic small-angle neutron scattering (SANS) cross section of these materials. In this review we summarize results on the micromagnetic simulation of magnetic SANS from two-phase nanocomposites. The decisive advantage of this approach resides in the possibility to scrutinize the individual magnetization Fourier contributions to the total magnetic SANS cross section, rather than their sum, which is generally obtained from the experiment. The procedure furnishes unique and fundamental information regarding magnetic neutron scattering from nanomagnets.
Quasielastic Diffuse Neutron Scattering from Fluorites in the Fast Ion Phase
DEFF Research Database (Denmark)
Clausen, K.; Hayes, W.; Hutchings, M.T
1981-01-01
Quasielastic diffuse coherent neutron scattering arising from the dynamically disordered anions in CaF2 and PbF2 has been investigated as the temperature is increased into the fast ion phase. The characteristic variation with scattering vector Image of the integrated intensity, S(Image ), can...... be accounted for by a model in which the most probable instantaneous configuration of the defective anions is a cluster centered at the mid-point of nearest-neighbour regular anion sites. The observed S(Image ,ω) is Lorentzian in ω and the width has a marked increase with temperature....
ππ-scattering in the quark confinement model. Phase shifts
International Nuclear Information System (INIS)
Efimov, G.V.; Ivanov, M.A.; Mashnik, S.G.
1989-01-01
The low-energy ππ-scattering is investigated in the Quark Confinement Model (QCM). The four-quark diagrams and the vector (ρ) and scalar (f 0 and ε) meson exchanges are taken into account. The scalar meson problem is discussed. The joint analysis of the decay f 0 →ππ width, s-wave lengths and phase shifts of the ππ-scattering indicates the existence of the broad scalar ε(700-800)-resonance with Γ ε→ππ ≥m ε . The obtained results are in satisfactory agreement with experimental data. 66 refs.; 13 figs.; 2 tabs
International Nuclear Information System (INIS)
Lv Yong-Gang; Ji Zi-Heng; Dong Da-Shan; Gong Qi-Huang; Shi Ke-Bin
2015-01-01
We propose and implement a wide-field vibrational phase contrast detection to obtain imaging of imaginary components of third-order nonlinear susceptibility in a coherent anti-Stokes Raman scattering (CARS) microscope with full suppression of the non-resonant background. This technique is based on the unique ability of recovering the phase of the generated CARS signal based on holographic recording. By capturing the phase distributions of the generated CARS field from the sample and from the environment under resonant illumination, we demonstrate the retrieval of imaginary components in the CARS microscope and achieve background free coherent Raman imaging. (paper)
Single-phase DECT with VNCT compared with three-phase CTU in patients with haematuria
Energy Technology Data Exchange (ETDEWEB)
Park, Jung Jae; Park, Byung Kwan; Kim, Chan Kyo [Sungkyunkwan University School of Medicine, Department of Radiology, Samsung Medical Center, Seoul (Korea, Republic of)
2016-10-15
To retrospectively evaluate the diagnostic performance of single-phase dual-energy CT (DECT) with virtual non-contrast CT (VNCT) compared with three-phase CT urography (CTU) in patients with haematuria. A total of 296 patients underwent three-phase CTU (NCT at 120 kVp; nephrographic phase and excretory phase DECTs at 140 kVp and 80 kVp) owing to haematuria. Diagnostic performances of CT scans were compared for detecting urothelial tumours and urinary stones. Dose-length product (DLP) was compared in relation to single-phase DECT and three-phase CTU Dose-length product (DLP) was compared in relation to single-phase DECT and three-phase CTU. Sensitivity and specificity for tumour were 95 % (19/20) and 98.9 % (273/276) on CTU, 95 % (19/20) and 98.2 % (271/276) on nephrographic phase DECT, and 90 % (18/20) and 98.2 % (271/276) on excretory phase DECT (P > 0.1). Of the 148 stones detected on NCT, 108 (73 %) and 100 (67.6 %) were detected on nephrographic phase and excretory phase VNCTs, respectively. The mean size of stones undetected on nephrographic and excretory VNCTs was measured as 1.5 ± 0.5 mm and 1.6 ± 0.6 mm, respectively. The mean DLPs of three-phase CTU, nephrographic phase DECT and excretory phase DECT were 1076 ± 248 mGy . cm, 410 ± 98 mGy . cm, and 360 ± 87 mGy . cm, respectively (P < 0.001). Single-phase DECT has a potential to replace three-phase CTU for detecting tumours with a lower radiation dose. (orig.)
A single phase multilevel inverter as power converter for 3-phase ...
African Journals Online (AJOL)
A single phase multilevel inverter as power converter for 3-phase electric loads. ... m-phase maker was simulated using MATLAB and the results confirmed the excellent perfor-mance of the RBNPS. The listed advantages attained could be incorporated in the design and operation of a converter for an electric drive of a car.
The effect of scattering on single photon transmission of optical angular momentum
International Nuclear Information System (INIS)
Andrews, D L
2011-01-01
Schemes for the communication and registration of optical angular momentum depend on the fidelity of transmission between optical system components. It is known that electron spin can be faithfully relayed between exciton states in quantum dots; it has also been shown by several theoretical and experimental studies that the use of beams conveying orbital angular momentum can significantly extend the density and efficiency of such information transfer. However, it remains unclear to what extent the operation of such a concept at the single photon level is practicable—especially where this involves optical propagation through a material system, in which forward scattering events can intervene. The possibility of transmitting and decoding angular momentum over nanoscale distances itself raises other important issues associated with near-field interrogation. This paper provides a framework to address these and related issues. A quantum electrodynamical representation is constructed and used to pursue the consequences of individual photons, from a Laguerre–Gaussian beam, undergoing single and multiple scattering events in the course of propagation. In this context, issues concerning orbital angular momentum conservation, and its possible compromise, are tackled by identifying the relevant components of the electromagnetic scattering and coupling tensors, using an irreducible Cartesian basis. The physical interpretation broadly supports the fidelity of quantum information transmission, but it also identifies potential limitations of principle
The effect of scattering on single photon transmission of optical angular momentum
Andrews, D. L.
2011-06-01
Schemes for the communication and registration of optical angular momentum depend on the fidelity of transmission between optical system components. It is known that electron spin can be faithfully relayed between exciton states in quantum dots; it has also been shown by several theoretical and experimental studies that the use of beams conveying orbital angular momentum can significantly extend the density and efficiency of such information transfer. However, it remains unclear to what extent the operation of such a concept at the single photon level is practicable—especially where this involves optical propagation through a material system, in which forward scattering events can intervene. The possibility of transmitting and decoding angular momentum over nanoscale distances itself raises other important issues associated with near-field interrogation. This paper provides a framework to address these and related issues. A quantum electrodynamical representation is constructed and used to pursue the consequences of individual photons, from a Laguerre-Gaussian beam, undergoing single and multiple scattering events in the course of propagation. In this context, issues concerning orbital angular momentum conservation, and its possible compromise, are tackled by identifying the relevant components of the electromagnetic scattering and coupling tensors, using an irreducible Cartesian basis. The physical interpretation broadly supports the fidelity of quantum information transmission, but it also identifies potential limitations of principle.
Cannaday, Ashley E.; Draham, Robert; Berger, Andrew J.
2016-04-01
The goal of this project is to estimate non-nuclear organelle size distributions in single cells by measuring angular scattering patterns and fitting them with Mie theory. Simulations have indicated that the large relative size distribution of organelles (mean:width≈2) leads to unstable Mie fits unless scattering is collected at polar angles less than 20 degrees. Our optical system has therefore been modified to collect angles down to 10 degrees. Initial validations will be performed on polystyrene bead populations whose size distributions resemble those of cell organelles. Unlike with the narrow bead distributions that are often used for calibration, we expect to see an order-of-magnitude improvement in the stability of the size estimates as the minimum angle decreases from 20 to 10 degrees. Scattering patterns will then be acquired and analyzed from single cells (EMT6 mouse cancer cells), both fixed and live, at multiple time points. Fixed cells, with no changes in organelle sizes over time, will be measured to determine the fluctuation level in estimated size distribution due to measurement imperfections alone. Subsequent measurements on live cells will determine whether there is a higher level of fluctuation that could be attributed to dynamic changes in organelle size. Studies on unperturbed cells are precursors to ones in which the effects of exogenous agents are monitored over time.
Hakem, I F; Benmouna, A; Benmouna, R; Ferebee, R; Benmouna, M; Bockstaller, M R
2014-06-01
The scattering characteristics of block copolymer (BCP)/nanoparticle (NP) blend systems are analyzed in the weak segregation limit using random phase approximation (RPA). The scattering function is established and shown to adequately capture reported data of small-angle neutron scattering in poly(norbornene-b -d-norbornene dicarboxylic acid)/ Fe3O4 nanoparticle blend systems over the entire small-angle range for a variety of BCP and NP compositions. Besides predicting the relevant length scales of microstructure formation, the RPA analysis reveals the increase of segregation in the BCP system upon NP addition. The insight into the thermodynamics of microstructure formation in BCP/NP blend systems that is provided by the RPA analysis should be a valuable asset for the design of BCP-based microstructured hybrid materials with predetermined structure and properties.
Non-Markovian dynamics of a qubit due to single-photon scattering in a waveguide
Fang, Yao-Lung L.; Ciccarello, Francesco; Baranger, Harold U.
2018-04-01
We investigate the open dynamics of a qubit due to scattering of a single photon in an infinite or semi-infinite waveguide. Through an exact solution of the time-dependent multi-photon scattering problem, we find the qubit's dynamical map. Tools of open quantum systems theory allow us then to show the general features of this map, find the corresponding non-Linbladian master equation, and assess in a rigorous way its non-Markovian nature. The qubit dynamics has distinctive features that, in particular, do not occur in emission processes. Two fundamental sources of non-Markovianity are present: the finite width of the photon wavepacket and the time delay for propagation between the qubit and the end of the semi-infinite waveguide.
Large-scale single-crystal growth of (CH3)2NH2CuCl3 for neutron scattering experiments
Park, Garam; Oh, In-Hwan; Park, J. M. Sungil; Park, Seong-Hun; Hong, Chang Seop; Lee, Kwang-Sei
2016-05-01
Neutron scattering studies on low-dimensional quantum spin systems require large-size single-crystals. Single-crystals of (CH3)2NH2CuCl3 showing low-dimensional magnetic behaviors were grown by a slow solvent evaporation method in a two-solvent system at different temperature settings. The best results were obtained for the bilayer solution of methanol and isopropanol with a molar ratio of 2:1 at 35 °C. The quality of the obtained single-crystals was tested by powder and single-crystal X-ray diffraction and single-crystal neutron diffraction. In addition, to confirm structural phase transitions (SPTs), thermal analysis and single-crystal X-ray diffraction at 300 K and 175 K, respectively, were conducted, confirming the presence of a SPT at Tup=288 K on heating and Tdown=285 K on cooling.
Czech Academy of Sciences Publication Activity Database
Holoubek, Jaroslav
2000-01-01
Roč. 162, - (2000), s. 307-322 ISSN 1022-1360. [Data Evaluation in Light Scattering of Polymers. Bad-Schandau, 06.10.1999-08.10.1999] R&D Projects: GA ČR GA203/99/0573; GA AV ČR IAA4050902 Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 0.406, year: 2000
Marshak, Alexander; Knyazikhin, Yuri; Chiu, J. Christine; Wiscombe, Warren J.
2012-01-01
The single scattering albedo omega(sub O lambda) in atmospheric radiative transfer is the ratio of the scattering coefficient to the extinction coefficient. For cloud water droplets both the scattering and absorption coefficients, thus the single scattering albedo, are functions of wavelength lambda and droplet size r. This note shows that for water droplets at weakly absorbing wavelengths, the ratio omega(sub O lambda)(r)/omega(sub O lambda)(r (sub O)) of two single scattering albedo spectra is a linear function of omega(sub O lambda)(r). The slope and intercept of the linear function are wavelength independent and sum to unity. This relationship allows for a representation of any single scattering albedo spectrum omega(sub O lambda)(r) via one known spectrum omega(sub O lambda)(r (sub O)). We provide a simple physical explanation of the discovered relationship. Similar linear relationships were found for the single scattering albedo spectra of non-spherical ice crystals.
Instantaneous power flow determination for single-phase UPFC
Energy Technology Data Exchange (ETDEWEB)
Dobrucky, B.; Drozdy, S.; Pokorny, M.; Pavlanin, R. [Zilina Univ., Zilina (Slovakia)
2007-07-01
The parallel shunt active filter in a unified power flow conditioner (UPFC) can filter and compensate the reactive power of basic and higher current harmonics. This paper reported on a study in which a new theory of orthogonal transform was used to control a single-phase UPFC system and transform it into a two-axes system. In addition to estimating the load current phase shifts, the study also determined the instantaneous active and reactive powers. The new theory is based on the premise that ordinary single-phase quantity can be complemented by a virtual fictitious phase so that both of them will create an orthogonal system, as is usual in three-phase systems. The theory uses efficient methods of analysis, such as time-sub-optimal determination of fundamental harmonics; average- and/or root-mean-square values; or instantaneous reactive power methods. The load current phase shift can be used to compensate for voltage drops. This paper outlined a practical application of the method in a case of active and reactive power determination for single-phase UPFC. It also presented some examples of the successful simulation experiments results focused on regulation output voltage of UPFC. 9 refs., 13 figs., 1 appendix.
Monte Carlo Modelling of Single-Crystal Diffuse Scattering from Intermetallics
Directory of Open Access Journals (Sweden)
Darren J. Goossens
2016-02-01
Full Text Available Single-crystal diffuse scattering (SCDS reveals detailed structural insights into materials. In particular, it is sensitive to two-body correlations, whereas traditional Bragg peak-based methods are sensitive to single-body correlations. This means that diffuse scattering is sensitive to ordering that persists for just a few unit cells: nanoscale order, sometimes referred to as “local structure”, which is often crucial for understanding a material and its function. Metals and alloys were early candidates for SCDS studies because of the availability of large single crystals. While great progress has been made in areas like ab initio modelling and molecular dynamics, a place remains for Monte Carlo modelling of model crystals because of its ability to model very large systems; important when correlations are relatively long (though still finite in range. This paper briefly outlines, and gives examples of, some Monte Carlo methods appropriate for the modelling of SCDS from metallic compounds, and considers data collection as well as analysis. Even if the interest in the material is driven primarily by magnetism or transport behaviour, an understanding of the local structure can underpin such studies and give an indication of nanoscale inhomogeneity.
Single phase inverter for a three phase power generation and distribution system
Lindena, S. J.
1976-01-01
A breadboard design of a single-phase inverter with sinusoidal output voltage for a three-phase power generation and distribution system was developed. The three-phase system consists of three single-phase inverters, whose output voltages are connected in a delta configuration. Upon failure of one inverter the two remaining inverters will continue to deliver three-phase power. Parallel redundancy as offered by two three-phase inverters is substituted by one three-phase inverter assembly with high savings in volume, weight, components count and complexity, and a considerable increase in reliability. The following requirements must be met: (1) Each single-phase, current-fed inverter must be capable of being synchronized to a three-phase reference system such that its output voltage remains phaselocked to its respective reference voltage. (2) Each single-phase, current-fed inverter must be capable of accepting leading and lagging power factors over a range from -0.7 through 1 to +0.7.
Directory of Open Access Journals (Sweden)
Daqing Piao
2014-12-01
Full Text Available Recent focused Monte Carlo and experimental studies on steady-state single-fiber reflectance spectroscopy (SfRS from a biologically relevant scattering medium have revealed that, as the dimensionless reduced scattering of the medium increases, the SfRS intensity increases monotonically until reaching a plateau. The SfRS signal is semi-empirically decomposed to the product of three contributing factors, including a ratio-of-remission (RoR term that refers to the ratio of photons remitting from the medium and crossing the fiber-medium interface over the total number of photons launched into the medium. The RoR is expressed with respect to the dimensionless reduced scattering parameter , where is the reduced scattering coefficient of the medium and is the diameter of the probing fiber. We develop in this work, under the assumption of an isotropic-scattering medium, a method of analytical treatment that will indicate the pattern of RoR as a function of the dimensionless reduced scattering of the medium. The RoR is derived in four cases, corresponding to in-medium (applied to interstitial probing of biological tissue or surface-based (applied to contact-probing of biological tissue SfRS measurements using straight-polished or angle-polished fiber. The analytically arrived surface-probing RoR corresponding to single-fiber probing using a 15° angle-polished fiber over the range of agrees with previously reported similarly configured experimental measurement from a scattering medium that has a Henyey–Greenstein scattering phase function with an anisotropy factor of 0.8. In cases of a medium scattering light anisotropically, we propose how the treatment may be furthered to account for the scattering anisotropy using the result of a study of light scattering close to the point-of-entry by Vitkin et al. (Nat. Commun. 2011, doi:10.1038/ncomms1599.
Seasonal Trend of Aerosol Single Scattering Albedo at Biomass Burning Sites in Southern Africa
Eck, T. F.; Holben, B. N.; Reid, J. S.; Ward, D.; Mukelabai, M. M.; Piketh, S.; Hyer, E. J.; Dubovik, O.; Sinyuk, A.; Schafer, J. S.; Giles, D. M.; Smirnov, A.; Slutsker, I.
2011-12-01
A database of the optical properties of primarily biomass burning aerosols in Mongu, Zambia from multi-year monitoring at an AERONET sun-sky radiometer site was examined. For the biomass burning season months (July-November), we investigate the aerosol single scattering albedo (SSA), aerosol size distributions, and refractive indices from almucantar sky scan retrievals utilizing the algorithm of Dubovik and King (2000). The monthly mean single scattering albedo at 440 nm in Mongu was found to increase significantly from ~0.84 in July to ~0.93 in November (from 0.78 to 0.90 at 675 nm in these same months). There was no significant change in particle size, in either the dominant accumulation or secondary coarse modes during these months, nor any significant trend in the Angstrom Exponent (440-870 nm; r2=0.02). A significant downward seasonal trend in imaginary refractive index (r2=0.43) suggests a trend of decreasing black carbon content in the aerosol composition as the burning season progresses. Similarly, seasonal SSA retrievals for both the Etosha Pan, Namibia and Skukuza, South Africa AERONET sites also show increasing single scattering albedo values through the burning season. We show maps of satellite detected fire counts, which indicate that the regions of primary biomass burning in southern Africa shift significantly from July to October. Possible reasons for the seasonal changes in observed SSA include differences in biomass fuel types in different regions and seasons (fraction of woody biomass versus grasses), agricultural practices (Chitemene: in which woody fuels are burned at the end of the dry season), differences in fuel moisture content (as mid-October is the typical beginning of the rainy season) and differences in aging due to transport speed and distance from varying source regions. We also analyze the seasonality of SSA for sites in biomass burning regions of southern Amazonia, where no significant seasonal trend in SSA was detected.
Ultrafast Switching Superjunction MOSFETs for Single Phase PFC Applications
DEFF Research Database (Denmark)
Hernandez Botella, Juan Carlos; Petersen, Lars Press; Andersen, Michael A. E.
2014-01-01
This paper presents a guide on characterizing state-of-the-art silicon superjunction (SJ) devices in the 600V range for single phase power factor correction (PFC) applications. The characterization procedure is based on a minimally inductive double pulse tester (DPT) with a very low intrusive...... investigates the latest SJ devices in order to set a reference for future research on improvement over silicon (Si) attained with the introduction of wide bandgap devices in single phase PFC applications. The obtained results show that the latest generation of SJ devices set a new benchmark for its wide...
The Single-Phase ProtoDUNE Technical Design Report
Energy Technology Data Exchange (ETDEWEB)
Abi, B. [Univ. of Padova (Italy); et al.
2017-06-21
ProtoDUNE-SP is the single-phase DUNE Far Detector prototype that is under construction and will be operated at the CERN Neutrino Platform (NP) starting in 2018. ProtoDUNE-SP, a crucial part of the DUNE effort towards the construction of the first DUNE 10-kt fiducial mass far detector module (17 kt total LAr mass), is a significant experiment in its own right. With a total liquid argon (LAr) mass of 0.77 kt, it represents the largest monolithic single-phase LArTPC detector to be built to date. It's technical design is given in this report.
RED Collaboration; Akimov, D. Yu.; Alexandrov, I. S.; Aleshin, V. I.; Belov, V. A.; Bolozdynya, A. I.; Burenkov, A. A.; Chepurnov, A. S.; Danilov, M. V.; Derbin, A. V.; Dmitrenko, V. V.; Dolgolenko, A. G.; Egorov, D. A.; Efremenko, Yu. V.; Etenko, A. V.
2012-01-01
We propose to detect and to study neutrino neutral current coherent scattering off atomic nuclei with a two-phase emission detector using liquid xenon as a working medium. Expected signals and backgrounds are calculated for two possible experimental sites: Kalinin Nuclear Power Plant in the Russian Federation and Spallation Neutron Source at the Oak Ridge National Laboratory in the USA. Both sites have advantages as well as limitations. However the experiment looks feasible at either location...
DEFF Research Database (Denmark)
Bai, M.; Miskowiec, A.; Hansen, F. Y.
2012-01-01
High-energy-resolution quasielastic neutron scattering has been used to elucidate the diffusion of water molecules in proximity to single bilayer lipid membranes supported on a silicon substrate. By varying sample temperature, level of hydration, and deuteration, we identify three different types...... of diffusive water motion: bulk-like, confined, and bound. The motion of bulk-like and confined water molecules is fast compared to those bound to the lipid head groups (7-10 H2O molecules per lipid), which move on the same nanosecond time scale as H atoms within the lipid molecules. Copyright (C) EPLA, 2012...
Ha, Jae-Min; Jang, Hyung-Sik; Lim, Sung-Hwan; Choi, Sung-Min
2015-08-07
We have investigated the distributions of individually isolated and hydrophilically functionalized single-walled carbon nanotubes (p-SWNTs) in the Pluronic L121-water system at the reverse hexagonal phase using small-angle X-ray scattering (SAXS) and contrast-matched small-angle neutron scattering (SANS) measurements. As the p-SWNT-L121-water system is transitioned from the lamellar phase to the reverse hexagonal phase with temperature, p-SWNTs which were selectively distributed in the polar layers of the lamellar structure become selectively distributed in the cylindrical polar cores of the reverse hexagonal structure, forming a hexagonal array of p-SWNTs. This was clearly confirmed by the contrast-matched SANS measurements. The selective distribution of p-SWNTs in the reverse hexagonal phase is driven by the selective affinity of p-SWNTs to the polar domains of the block copolymer system. The method demonstrated in this study provides a new route for fabricating ordered SWNT superstructures and may be applicable for inorganic 1D nanoparticles such as semiconducting, metallic and magnetic nanorods which are of great interest.
Single-shot quantitative phase microscopy with color-multiplexed differential phase contrast (cDPC.
Directory of Open Access Journals (Sweden)
Zachary F Phillips
Full Text Available We present a new technique for quantitative phase and amplitude microscopy from a single color image with coded illumination. Our system consists of a commercial brightfield microscope with one hardware modification-an inexpensive 3D printed condenser insert. The method, color-multiplexed Differential Phase Contrast (cDPC, is a single-shot variant of Differential Phase Contrast (DPC, which recovers the phase of a sample from images with asymmetric illumination. We employ partially coherent illumination to achieve resolution corresponding to 2× the objective NA. Quantitative phase can then be used to synthesize DIC and phase contrast images or extract shape and density. We demonstrate amplitude and phase recovery at camera-limited frame rates (50 fps for various in vitro cell samples and c. elegans in a micro-fluidic channel.
Vargas, Susana; Millán-Chiu, Blanca E; Arvizu-Medrano, Sofía M; Loske, Achim M; Rodríguez, Rogelio
2017-06-01
A comparison between plate counting (PC) and dynamic light scattering (DLS) is reported. PC is the standard technique to determine bacterial population as a function of time; however, this method has drawbacks, such as the cumbersome preparation and handling of samples, as well as the long time required to obtain results. Alternative methods based on optical density are faster, but do not distinguish viable from non-viable cells. These inconveniences are overcome by using DLS. Two different bacteria strains were considered: Escherichia coli and Staphylococcus aureus. DLS was performed at two different illuminating conditions: continuous and intermittent. By the increment of particle size as a function of time, it was possible to observe cell division and the formation of aggregates containing very few bacteria. The scattered intensity profiles showed the lag phase and the transition to the exponential phase of growth, providing a quantity proportional to viable bacteria concentration. The results revealed a clear and linear correlation in both lag and exponential phase, between the Log 10 (colony-forming units/mL) from PC and the Log 10 of the scattered intensity I s from DLS. These correlations provide a good support to use DLS as an alternative technique to determine bacterial population. Copyright © 2017 Elsevier B.V. All rights reserved.
Probing scattering phases via two-center interferences in collisions of He2 + on CO
Gao, Y.; Zhang, S. F.; Zhu, X. L.; Guo, D. L.; Schulz, M.; Voitkiv, A. B.; Zhao, D. M.; Hai, B.; Zhang, M.; Zhang, R. T.; Feng, W. T.; Yan, S.; Wang, H. B.; Huang, Z. K.; Ma, X.
2018-02-01
Phases of quantum transition amplitudes contain very important information about physical processes. However, as a rule, they may not be accessed experimentally. This is, in particular, the case when collisions of ions and atoms are studied. In this rapid communication, we explore double-electron capture in collisions of α particles with CO molecules. Regarding the atomic cores of the molecule as two "slits," we show that atomic "double-slit" interference can be exploited to experimentally extract information about phases of the projectile scattering on the cores.
Investigation of effect of single phase electrical faults at LOFT
International Nuclear Information System (INIS)
Yeates, J.A.
1978-01-01
This LTR presents the general basic engineering facts related to an open phase fault in a three phase power system commonly referred to as a single phase condition. It describes the probable results to electrical motors and describes the LOFT system design factors which minimize the likelihood of such a fault occurring at LOFT. It recognizes that the hazard of such a fault is a realistic threat and notes the types of relays designed to provide protection. Recommendations are made to perform a detailed engineering study to determine the most advantageous protective relay design, and to implement such a design by installation of the necessary devices and controls
Ultrafast electric phase control of a single exciton qubit
Widhalm, Alex; Mukherjee, Amlan; Krehs, Sebastian; Sharma, Nandlal; Kölling, Peter; Thiede, Andreas; Reuter, Dirk; Förstner, Jens; Zrenner, Artur
2018-03-01
We report on the coherent phase manipulation of quantum dot excitons by electric means. For our experiments, we use a low capacitance single quantum dot photodiode which is electrically controlled by a custom designed SiGe:C BiCMOS chip. The phase manipulation is performed and quantified in a Ramsey experiment, where ultrafast transient detuning of the exciton energy is performed synchronous to double pulse π/2 ps laser excitation. We are able to demonstrate electrically controlled phase manipulations with magnitudes up to 3π within 100 ps which is below the dephasing time of the quantum dot exciton.
Burov, V. A.; Morozov, S. A.
2001-11-01
Wave scattering by a point-like inhomogeneity, i.e., a strong inhomogeneity with infinitesimal dimensions, is described. This type of inhomogeneity model is used in investigating the point-spread functions of different algorithms and systems. Two approaches are used to derive the rigorous relationship between the amplitude and phase of a signal scattered by a point-like acoustic inhomogeneity. The first approach is based on a Marchenko-type equation. The second approach uses the scattering by a scatterer whose size decreases simultaneously with an increase in its contrast. It is shown that the retarded and advanced waves are scattered differently despite the relationship between the phases of the corresponding scattered waves.
International Nuclear Information System (INIS)
Song, C.; Wermeille, D.; Goldman, A. I.; Canfield, P. C.; Rhee, J. Y.; Harmon, B. N.
2001-01-01
Resonant magnetic x-ray scattering measurements have been performed on a single crystal of TbNi 2 B 2 C to uniquely determine the modulation wave vector in the low-temperature orthorhombic phase. Below the transition temperature of 14.4(±0.1)K, two magnetic satellite peaks develop, centered on (h00) orth charge reflections. Our study shows that the longitudinal modulation of the magnetic moment is along the longer basal plane axes of the orthorhombic phase. Power law fits to the temperature dependence of the structural distortion, a/b-1, and the magnetic scattering intensity result in the same exponent, β, and transition temperature evidencing explicitly that the structural phase transition is magneto-elastic in origin
Stimulated Brillouin scattering continuous wave phase conjugation in step-index fiber optics.
Massey, Steven M; Spring, Justin B; Russell, Timothy H
2008-07-21
Continuous wave (CW) stimulated Brillouin scattering (SBS) phase conjugation in step-index optical fibers was studied experimentally and modeled as a function of fiber length. A phase conjugate fidelity over 80% was measured from SBS in a 40 m fiber using a pinhole technique. Fidelity decreases with fiber length, and a fiber with a numerical aperture (NA) of 0.06 was found to generate good phase conjugation fidelity over longer lengths than a fiber with 0.13 NA. Modeling and experiment support previous work showing the maximum interaction length which yields a high fidelity phase conjugate beam is inversely proportional to the fiber NA(2), but find that fidelity remains high over much longer fiber lengths than previous models calculated. Conditions for SBS beam cleanup in step-index fibers are discussed.
Studies of isotopic defined hydrogen beams scattering from Pd single-crystal surfaces
International Nuclear Information System (INIS)
Varlam, Mihai; Steflea, Dumitru
2001-01-01
An experimental investigation of hydrogen isotopes interaction with Pd single-crystal surface has been carried out using molecular beam technique. The energy dependence of the sticking probability and its relation with the trapping probability into the precursor state is studied by integrating the scattered angular distribution of hydrogen Isotopic defined beams from Pd (111) surface in the 40-400 K surface temperature range. The dependence has been evaluated by defining hydrogen molecular beams with different isotopic concentration - from the natural one to the 5% D/(D+H) ratio - and for different incident energies. The beam was directed onto a single-crystal Pd (111) surface. In the paper, we report the experimental results and some considerations related to it. (authors)
Studies of isotopic defined hydrogen beams scattering from Pd single-crystal surfaces
International Nuclear Information System (INIS)
Varlam, Mihai; Steflea, Dumitru
1999-01-01
An experimental investigation of hydrogen isotopes interaction with Pd single-crystal surfaces has been carried out using molecular beam technique. The energy dependence of the sticking probability and its relation with the trapping probability into the precursor state is studied by integrating the scattered angular distribution of hydrogen isotopic defined beams from Pd (111) surfaces in the 40 - 400 K surface temperature range. The dependence has been evaluated by defining hydrogen molecular beams with different isotopic concentration - from the natural one until 5% D/(D + H) and different incident energies and directed onto a single - crystal Pd (111) surface. In the paper, we report the experimental results and some considerations related to them. (authors)
Heterophase fluctuation of omega phase and X-ray diffuse scattering from dual phase structure
International Nuclear Information System (INIS)
Farjami, Susan; Kubo, Hiroshi
2003-01-01
Heterophase fluctuation of athermal omega embryos has been analyzed by assuming a dual phase structure of omega embryos composed of omega and bcc matrix phase. The two-dimensional modulation of dual phase was suggested from the quantitative estimation of coherent free energy of omega embryos using microscopic theory of elasticity and the Landau anharmonic theory for phase transformation. The X-ray diffraction theory was developed in connection to the formation of omega embryos having the dual phase structure. The offset of the diffuse peak position from the ideal omega point in the X-ray diffraction pattern is attributed to the dual phase (incommensurate phase) of omega embryos. It was also shown that the ellipsoidal shape of the diffuse intensity tailing toward the fundamental spot of the matrix phase is originated from the equilibrium shape of the omega embryo. The quantitative estimation of elastic energy modulus (EEM) in the disordered bcc matrix and in the ordered bcc matrix indicates a difference in the deviation amount of the minimum point k(q m ) from the ideal omega point k(q ω ) and a difference in the elliptical shape of embryos
the steady-state performance characteristics of single phase transfer
African Journals Online (AJOL)
2012-11-03
Nov 3, 2012 ... The paper reports the derivation of the steady- state equivalent circuit of a single phase transfer ... series opposition between the two halves of the ma- ..... from its equivalent circuit of fig 6 for different values of slip. Impedance due to forward field. Zf = Rf + jXf = Rr. 2(2s - 1). + jxr. 2. (19) in parallel with jxm. 2.
An Asymmetrical Space Vector Method for Single Phase Induction Motor
DEFF Research Database (Denmark)
Cui, Yuanhai; Blaabjerg, Frede; Andersen, Gert Karmisholt
2002-01-01
Single phase induction motors are the workhorses in low-power applications in the world, and also the variable speed is necessary. Normally it is achieved either by the mechanical method or by controlling the capacitor connected with the auxiliary winding. Any above method has some drawback which...
Improvement of Torque Production in Single-Phase Induction Motors ...
African Journals Online (AJOL)
Existing single phase induction motors exhibit low starting torque. Moreover, during accelerating time and at steady state, they produce a significant level of torque pulsations which gives rise to noise and vibration in the machine. As part of efforts to mitigate these problems, a performance improvement strategy using a PWM ...
experimental implementation of single-phase, three-level, sinusoidal
African Journals Online (AJOL)
Experimental Implementation of SPWM VSI with R-L Load. 3. Figure 2: Switching pattern of the proposed single-phase, three-level PWM inverter. Figure 3: Prototype setup. (a) Power circuits for both inverters. (b) Logic and Driver circuits. Nigerian Journal of Technology. Vol. 31, No. 1, March 2012.
A single phase photovoltaic inverter control for grid connected system
Indian Academy of Sciences (India)
This paper presents a control scheme for single phase grid connected photovoltaic (PV) system operating under both grid connected and isolated grid mode. The control techniques include voltage and current control of grid-tie PV inverter. During grid connected mode, grid controls the amplitude and frequency of the PV ...
Load compensation for single phase system using series active filter ...
African Journals Online (AJOL)
In this paper a new control strategy for series active filter has been proposed for improvement of power quality problems in single phase system. Since the non linear loads in the system comprises of both voltage source harmonic and current source harmonic loads and the dominancy of each type of load varies from time to ...
Persistent Scatterer Aided Facade Lattice Extraction in Single Airborne Optical Oblique Images
Schack, L.; Soergel, U.; Heipke, C.
2015-03-01
We present a new method to extract patterns of regular facade structures from single optical oblique images. To overcome the missing three-dimensional information we incorporate structural information derived from Persistent Scatter (PS) point cloud data into our method. Single oblique images and PS point clouds have never been combined before and offer promising insights into the compatibility of remotely sensed data of different kinds. Even though the appearance of facades is significantly different, many characteristics of the prominent patterns can be seen in both types of data and can be transferred across the sensor domains. To justify the extraction based on regular facade patterns we show that regular facades appear rather often in typical airborne oblique imagery of urban scenes. The extraction of regular patterns is based on well established tools like cross correlation and is extended by incorporating a module for estimating a window lattice model using a genetic algorithm. Among others the results of our approach can be used to derive a deeper understanding of the emergence of Persistent Scatterers and their fusion with optical imagery. To demonstrate the applicability of the approach we present a concept for data fusion aiming at facade lattices extraction in PS and optical data.
protoDUNE-Single Phase and protDUNE-DualPhase
Brice, Maximilien
2016-01-01
At the EHN1 two big 8m x 8m x8m detector prototypes (protoDUNE-Single Phase and protDUNE-DualPhase) are being constructed. The aim is to test technologies and detector performances for DUNE, a new generation of LBN neutr
Single-Phase Phase-Locked Loop Based on Derivative Elements
DEFF Research Database (Denmark)
Guan, Qingxin; Zhang, Yu; Kang, Yong
2017-01-01
High-performance phase-locked loops (PLLs) are critical for power control in grid-connected systems. This paper presents a new method of designing a PLL for single-phase systems based on derivative elements (DEs). The quadrature signal generator (QSG) is constructed by two DEs with the same...
Regge-pole description of potential scattering by means of the phase-integral method
International Nuclear Information System (INIS)
Amaha, A.
1992-01-01
The application of Regge-pole theory to different atomic and molecular scattering has shown to have promising interpretational power in the differential cross sections. Differential cross sections can be analysed in terms of interference between the 'background' amplitude and a few Regge-pole positions of the scattering matrix (S matrix) representing surface waves around the interaction region. By the analytic continuation of the radial Schroedinger differential equation into the complex plane of angular momentum one can determine the analytic properties of the S matrix which contains the physical information in the scattering processes. For interaction potentials fulfilling certain properties, the study of the S matrix leads to the study of the F matrix introduced by Froeman and Froeman for the treatment of connection problems for phase-integral solutions of the differential equation. In this thesis the quantum mechanical scattering problem is analysed in the framework of Regge-pole theory with the use of the complex-angular-momentum formalism. To determine the S matrix, the relevant F matrix elements which give the stokes constants are derived and their properties are studied. The poles of the S matrix for particular complex values of the angular momentum quantum number are the Regge-poles. Using the Regge-pole positions and residues together with the background integral, the differential cross sections are calculated and compared with corresponding partial-wave representations
Neutron and x-ray scattering studies of ferroelectric phase transitions
International Nuclear Information System (INIS)
Dolling, G.
1982-08-01
The subject of ferroelectric type phase transitions is introduced by means of examples of two main classes (a) displacive transitions, e.g. KNbO 3 , and (b) order-disorder transitions, e.g. NaNO 2 . The significance of crystal structure and crystal dynamics (i.e. the phonon dispersion relations) for ferroelectric behaviour is emphasized. The chief methods for structure determination are x-ray and neutron diffraction, while the most powerful of all techniques for studying phonon properties is that of coherent inelastic neutron scattering. The most useful type of neutron spectrometer for phase transition studies, the triple axis crystal spectrometer, is discussed in detail. The history of the soft mode theory of displacive phase transitions, and its application to the antiferroelectric and 'almost ferroelectric' transitions in SrTiO 3 , provides an introduction to more recent developments in this area, including over-damped soft modes, central peaks and critical scattering, incommensurate phase transitions (e.g. K 2 SeO 4 ), amplitudons, phasons and finally solitions. The treatment throughout is descriptive and introductory, designed for graduate students
National Aeronautics and Space Administration — This proposal addresses a proof-of-concept study using Raman Scattering to distinguish both the particle phase and particle temperature in the Propulsion System Lab...
Solution of the Cox-Thompson inverse scattering problem using finite set of phase shifts
Apagyi, B; Scheid, W
2003-01-01
A system of nonlinear equations is presented for the solution of the Cox-Thompson inverse scattering problem (1970 J. Math. Phys. 11 805) at fixed energy. From a given finite set of phase shifts for physical angular momenta, the nonlinear equations determine related sets of asymptotic normalization constants and nonphysical (shifted) angular momenta from which all quantities of interest, including the inversion potential itself, can be calculated. As a first application of the method we use input data consisting of a finite set of phase shifts calculated from Woods-Saxon and box potentials representing interactions with diffuse or sharp surfaces, respectively. The results for the inversion potentials, their first moments and asymptotic properties are compared with those provided by the Newton-Sabatier quantum inversion procedure. It is found that in order to achieve inversion potentials of similar quality, the Cox-Thompson method requires a smaller set of phase shifts than the Newton-Sabatier procedure.
Quantum scattering theory of a single-photon Fock state in three-dimensional spaces.
Liu, Jingfeng; Zhou, Ming; Yu, Zongfu
2016-09-15
A quantum scattering theory is developed for Fock states scattered by two-level systems in three-dimensional free space. It is built upon the one-dimensional scattering theory developed in waveguide quantum electrodynamics. The theory fully quantizes the incident light as Fock states and uses a non-perturbative method to calculate the scattering matrix.
Angular-domain scattering interferometry.
Shipp, Dustin W; Qian, Ruobing; Berger, Andrew J
2013-11-15
We present an angular-scattering optical method that is capable of measuring the mean size of scatterers in static ensembles within a field of view less than 20 μm in diameter. Using interferometry, the method overcomes the inability of intensity-based models to tolerate the large speckle grains associated with such small illumination areas. By first estimating each scatterer's location, the method can model between-scatterer interference as well as traditional single-particle Mie scattering. Direct angular-domain measurements provide finer angular resolution than digitally transformed image-plane recordings. This increases sensitivity to size-dependent scattering features, enabling more robust size estimates. The sensitivity of these angular-scattering measurements to various sizes of polystyrene beads is demonstrated. Interferometry also allows recovery of the full complex scattered field, including a size-dependent phase profile in the angular-scattering pattern.
Nowell, H.; Liu, G.
2012-12-01
With the advent of satellites, we can now observe areas of the globe that have sparse to no ground data coverage. Both active and passive satellite sensors aboard satellites including CloudSat's Cloud Profiling Radar (CPR), Aqua's Advanced Microwave Scanning Radiometer (AMSR-E) and the upcoming Global Precipitation Measurement's (GPM) Dual-Frequency Precipitation Radar (DPR) and GPM Microwave Imager (GMI) study ice and snow particles. A good retrieval algorithm for these satellite sensors can only be developed when the single scattering properties of the snowflakes are accurately calculated in radiative transfer models. This becomes crucial at frequencies at and above the W-band when aggregate ice crystals become detectable by satellite radiometers. Snowflakes are often modeled as spheres or oblate spheroids to ease the complexity of calculations, despite the fact that they are typically aggregates of crystals. For improved accuracy in satellite remote sensing, it is important to model snowflakes as close to nature as possible. Several recent studies model flakes as pristine crystal types [Liu, 2008], generate aggregate flakes as fractals [Ishimoto, 2008] or via the Monte Carlo method [Maruyama and Fujioshi, 2005]. Modeling snowflakes as pristine crystals, however, has the drawback of not accurately reflecting snowflakes as most tend to be aggregates of different crystal types. Other studies where aggregates are generated tend to overlook size-density relationships of aggregate flakes or other studied statistical parameters such as aspect ratio. In an effort to improve available single-scattering properties of aggregate flakes, we developed a new method of generating flakes. Starting out with a six-bullet rosette crystal of accurate size and density, aggregate flakes are generated with two different bullet rosette crystal sizes of 200 and/or 400 microns in maximum dimension. The flakes similarly follow size-density relationships of aggregate as determined from
Photon scattering by isolated isotopic impurities in single crystals of helium
International Nuclear Information System (INIS)
Lawson, D.T.
1972-01-01
Thermal conductivity measurements of oriented single crystals of hexagonal close-packed 4 He have been made in order to study the scattering of phonons by isotopic impurities. The samples, all grown at a constant pressure of 85.1 atmospheres, contained 3 He concentrations ranging from less than 10 - 6 to 2 x 10 - 5 . Apparatus and techniques have been developed which allow the growth of crystals at preferred orientations: c-axis orientations of 0 and 90 0 with respect to the direction of heat flow were chosen for this study. Quality and orientation of the sample crystals were determined from the thermal conductivity measurements themselves. In the 90 0 crystals an isotopic concentration of 2 x 10 - 5 reduces the thermal conductivity peak by a factor of 2.8. A model using the dominant phonon approximation to define an average isotope cross section for phonon scattering fits these data well. The cross section thus obtained is larger than can be explained by scattering from the mass defect alone, and provides a measure of the lattice distortion accompanying an isotopic substitution. Relevant theories are examined in the light of these results. The data for 0 0 crystals are consistent with the same cross section if samples displaying the same effective phonon mean free path in the low temperature limit are compared. Variations in this limiting mean free path are attributed to specular reflection of phonons at the sample chamber walls. At the lowest 3 He concentrations Poiseuille flow of phonons causes a peak in the effective mean free path a factor of 4.6 higher than the low temperature limit
Improved PLL structures for single-phase grid inverters
DEFF Research Database (Denmark)
Ciobotaru, Mihai; Teodorescu, Remus; Blaabjerg, Frede
2005-01-01
of the reference signals. This paper presents two improved phase-locked-loop (PLL) methods for single-phase grid connected systems. The investigated PLL methods are based on a transport delay method and an inverse Park transformation method. The improvements in the case of using the delay-based PLL are: non......-frequency dependent and better filtering of the harmonics. For the other investigated PLL method based on inverse Park transformation the improvement consists of better filtering of the harmonics. Experimental results validate the effectiveness of the two proposed methods....
Dynamics Assessment of Advanced Single-Phase PLL Structures
DEFF Research Database (Denmark)
Golestan, Saeed; Monfarad, Mohammad; Freijedo, Francisco D.
2013-01-01
, and desired performance under frequency-varying and harmonically distorted grid conditions. Despite the wide acceptance and use of these two advanced PLLs, no comprehensive design guidelines to fine-tune their parameters have been reported yet. Through a detailed mathematical analysis it is shown......Recently, several advanced phase locked loop (PLL) techniques have been proposed for single-phase applications. Among these, the Park-PLL, and the second order generalized integrator (SOGI) based PLL are very attractive, owing to their simple digital implementation, low computational burden...
Ferroelectric phase transition in Ga2Te3 single crystals
Gamal, G. A.; Abdalrahman, M. M.; Ashraf, M. I.; Eman, H. J.
2005-01-01
Measurements of the electrical conductivity and Hall effect were carried out in a wide temperature range (200-500 K) for Ga2Te3 crystals. The crystals were grown in single crystalline form by making a modification of the travelling heater method technique. The measurements revealed unusual observations in the electric conductivity and Hall mobility indicating the presence of some type of phase transitions at about 430 K. So, ferroelectric behavior was examined for confirming the presence of second-order (ferroelectric) phase transition. An energy gap of 1.21 eV and depth of the impurity center of 0.11 eV were found.
Evaluation of thromboembolic disease using single dose dual phase scintigraphy
International Nuclear Information System (INIS)
Sharma, A.R.; Charan, S.; Silva, I.
2004-01-01
Introduction: Clinical presentation of thromboembolic disease (TED) is caused by three mechanisms 1) obstruction to venous outflow 2) vascular inflammation and 3) pulmonary emboli. Single Dose (Tc-99m MAA) Dual Phases (Veno-Pulmonary) scintigraphy is theoretically capable of evaluating two of three above mentioned patho-physiological factors. Therefore, a prospective study was designed to explore potential of Single Dose Dual Phase (SDDP) scintigraphy in the evaluation of thromboembolic disease. Materials and methods: Sixty consecutive patients with high clinical likelihood of thromboembolic disease (onset of painful and edematous lower limb, chest pain, shortness of breath, presence of risk factors for DVT, H/o of previous episode of DVT, right ventricular strain on ECHO, hypoxaemia on blood gas analysis), were included in this study. There were 43 men and 17 women (mean age 36 years). They were subjected to single dose dual phase (SDDP) scintigraphy using Tc-99m MAA (4 mci). Firstly venous phase of imaging was obtained with simultaneous injection of Tc-99m MAA diluted in 10 ml normal saline in syringe into superficial veins of dorsum of both feet (large volume continuous flow technique) in whole body acquisition mode on Dual Detectors Gamma Camera; followed by lung perfusion scintigraphy in conventional projections as second phase of study. Venous phase (Venography) was interpreted as per Ziffer's criteria in four venous segments (Unpaired- Inferior Vena Cava, 3 paired - Iliac, Femoral and Popliteal). Interpretation of lung perfusion scan was made as per PIOPED Criteria. Results: Forty-one of sixty patients (67%) showed scintigraphic evidence of venous occlusion (DVT) during venous phase. Out of these, 17 patients eventually had high probability lung scan for pulmonary embolism (29%). None of the patient with negative venous phase (n=19) showed perfusion defects on lung perfusion scan. Venous thrombosis most commonly affected the left lower limb (n=29, 71%). In 5
Effects of single particle on shape phase transitions and phase coexistence in odd-even nuclei
Yu, Xiang-Ru; Hu, Jing; Li, Xiao-Xue; An, Si-Yu; Zhang, Yu
2018-02-01
A classical analysis of shape phase transitions and phase coexistence in odd-even nuclei has been performed in the framework of the interacting boson-fermion model. The results indicate that the effects of a single particle may influence different types of transitions in different ways. Especially, it is revealed that phase coexistence can clearly emerge in the critical region and thus be taken as a indicator of the shape phase transitions in odd-even nuclei. Supported by National Natural Science Foundation of China (11375005)
International Nuclear Information System (INIS)
Furusaka, M.; Fujikawa, S.I.
1993-01-01
To study phase separation kinetics of Al-9.5at.%Li polycrystalline alloys in which precipitates have ordered Al 3 Li (δ') structure, profile analysis of small-angle neutron scattering and superlattice reflections (100) and (110) were done. A small-angle scattering instrument and a triple-axis spectrometer in elastic mode were used in the measurements. Strong texture was observed in the reflections. Therefore, measurements were done using the crystal orientation where the intensity of the reflection was at the maximum. Profiles of small-angle scattering and superlattice reflections were almost identical at higher momentum transfer side. At lower momentum transfer side, small-angle scattering showed interference effects, but superlattice reflection did not show any sign of interference. Integrated intensities of superlattice reflections were obtained and compared with small-angle scattering intensity. The order parameter was not saturated in the δ' precipitates at the early stage of the phase separation process
Directory of Open Access Journals (Sweden)
Annepu Venkata Naga Vamsi
2016-01-01
Full Text Available We have reported the measurement of temperature by using coherent anti-Stroke and coherent Stroke Raman scattering using superconducting nano wire single-photon detector. The measured temperatures by both methods (Coherent Anti-Raman scattering & Coherent Stroke Raman scattering and TC 340 are in good accuracy of ± 5 K temperature range. The length of the pipe line under test can be increased by increasing the power of the pump laser. This methodology can be widely used to measure temperatures at instantaneous positions in test pipe line or the entire temperature of the pipe line under test.
International Nuclear Information System (INIS)
Grigor'ev, A.N.; Dikij, N.P.; Matyash, P.P.; Nikolajchuk, L.I.; Pivovar, L.I.
1974-01-01
The radiation defects in semiconducting CdS single crystals induced during doping with 140 keV Na ions (10 15 -2.10 16 ion/cm 2 ) were studied by the orientation dependence of 700 keV proton backscattering. The absence of discrete peaks in the scattered proton eneryg spectra indicates a small contribution of direct scattering at large angles. The defects formed during doping increase the fractionof dechanneled particles, which are then scattered at large anlges. No amorphization of CdS was observed at high Na ion dose 2x10 16 ion/cm 2
Resonant anti-Stokes Raman scattering in single-walled carbon nanotubes
Gordeev, Georgy; Jorio, Ado; Kusch, Patryk; Vieira, Bruno G. M.; Flavel, Benjamin; Krupke, Ralph; Barros, Eduardo B.; Reich, Stephanie
2017-12-01
The dependence of the anti-Stokes Raman intensity on the excitation laser energy in carbon nanotubes is studied by resonant Raman spectroscopy. The complete resonant anti-Stokes and Stokes Raman profiles of the high-energy longitudinal phonon (G+) are obtained for (8,3), (7,5), (6,4), and (6,5) single chirality enriched samples. A high asymmetry between the intensity of the incoming and outgoing resonance is observed in the resonant Raman profiles. In contrast to Stokes scattering, anti-Stokes scattering is more intense at the outgoing resonance then at the incoming resonance. The resonance profiles are explained by a Raman process that includes the phonon-mediated interactions with the dark excitonic state. The chirality dependence of the Raman profiles is due to the variation in the exciton-phonon matrix elements, in agreement with tight-binding calculations. Based on the asymmetric Raman profiles we present the resonance factors for the Stokes/anti-Stokes ratios in carbon nanotubes.
Using Single-Scattering Albedo Spectral Curvature to Characterize East Asian Aerosol Mixtures
Li, Jing; Carlson, Barbara E.; Lacis, Andrew A.
2015-01-01
Spectral dependence of aerosol single-scattering albedo (SSA) has been used to infer aerosol composition. In particular, aerosol mixtures dominated by dust absorption will have monotonically increasing SSA with wavelength while that dominated by black carbon absorption has monotonically decreasing SSA spectra. However, by analyzing SSA measured at four wavelengths, 440, 675, 870, and 1020 nm from the Aerosol Robotic Network data set, we find that the SSA spectra over East Asia are frequently peaked at 675 nm. In these cases, we suggest that SSA spectral curvature, defined as the negative of the second derivative of SSA as a function of wavelength, can provide additional information on the composition of these aerosol mixtures. Aerosol SSA spectral curvatures for East Asia during fall and winter are considerably larger than those found in places primarily dominated by biomass burning or dust aerosols. SSA curvature is found to increase as the SSA magnitude decreases. The curvature increases with coarse mode fraction (CMF) to a CMF value of about 0.4, then slightly decreases or remains constant at larger CMF. Mie calculations further verify that the strongest SSA curvature occurs at approx. 40% dust fraction, with 10% scattering aerosol fraction. The nonmonotonic SSA spectral dependence is likely associated with enhanced absorption in the shortwave by dust, absorption by black carbon at longer wavelengths, and also the flattened absorption optical depth spectral dependence due to the increased particle size.
Four-jet production in single- and double-parton scattering within high-energy factorization
Energy Technology Data Exchange (ETDEWEB)
Kutak, Krzysztof; Maciula, Rafal; Serino, Mirko [The H. Niewodniczański Institute of Nuclear Physics, Polish Academy of Sciences,Radzikowskiego 152, 31-342 Kraków (Poland); Szczurek, Antoni [The H. Niewodniczański Institute of Nuclear Physics, Polish Academy of Sciences,Radzikowskiego 152, 31-342 Kraków (Poland); Faculty of Mathematics and Natural Sciences, University of Rzeszów,ul. Pigonia 1, 35-310 Rzeszów (Poland); Hameren, Andreas van [The H. Niewodniczański Institute of Nuclear Physics, Polish Academy of Sciences,Radzikowskiego 152, 31-342 Kraków (Poland)
2016-04-28
We perform a first study of 4-jet production in a complete high-energy factorization (HEF) framework. We include and discuss contributions from both single-parton scattering (SPS) and double-parton scattering (DPS). The calculations are performed for kinematical situations relevant for two experimental measurements (ATLAS and CMS) at the LHC. We compare our results to those reported by the ATLAS and CMS collaborations for different sets of kinematical cuts. The results of the HEF approach are compared with their counterparts for collinear factorization. For symmetric cuts the DPS HEF result is considerably smaller than the one obtained with collinear factorization. The mechanism leading to this difference is of kinematical nature. We conclude that an analysis of inclusive 4-jet production with asymmetric p{sub T}-cuts below 50 GeV would be useful to enhance the DPS contribution relative to the SPS contribution. In contrast to the collinear approach, the HEF approach nicely describes the distribution of the ΔS variable, which involves all four jets and their angular correlations.
Pressure Drop Correlations of Single-Phase and Two-Phase Flow in Rolling Tubes
International Nuclear Information System (INIS)
Xia-xin Cao; Chang-qi Yan; Pu-zhen Gao; Zhong-ning Sun
2006-01-01
A series of experimental studies of frictional pressure drop for single phase and two-phase bubble flow in smooth rolling tubes were carried out. The tube inside diameters were 15 mm, 25 mm and 34.5 mm respectively, the rolling angles of tubes could be set as 10 deg. and 20 deg., and the rolling periods could be set as 5 s, 10 s and 15 s. Combining with the analysis of single-phase water motion, it was found that the traditional correlations for calculating single-phase frictional coefficient were not suitable for the rolling condition. Based on the experimental data, a new correlation for calculating single-phase frictional coefficient under rolling condition was presented, and the calculations not only agreed well with the experimental data, but also could display the periodically dynamic characteristics of frictional coefficients. Applying the new correlation to homogeneous flow model, two-phase frictional pressure drop of bubble flow in rolling tubes could be calculated, the results showed that the relative error between calculation and experimental data was less than ± 25%. (authors)
Arahman, Nasrul; Maimun, Teuku; Mukramah, Syawaliah
2017-01-01
The composition of polymer solution and the methods of membrane preparation determine the solidification process of membrane. The formation of membrane structure prepared via non-solvent induced phase separation (NIPS) method is mostly determined by phase separation process between polymer, solvent, and non-solvent. This paper discusses the phase separation process of polymer solution containing Polyethersulfone (PES), N-methylpirrolidone (NMP), and surfactant Tetronic 1307 (Tet). Cloud point experiment is conducted to determine the amount of non-solvent needed on induced phase separation. Amount of water required as a non-solvent decreases by the addition of surfactant Tet. Kinetics of phase separation for such system is studied by the light scattering measurement. With the addition of Tet., the delayed phase separation is observed and the structure growth rate decreases. Moreover, the morphology of fabricated membrane from those polymer systems is analyzed by scanning electron microscopy (SEM). The images of both systems show the formation of finger-like macrovoids through the cross-section.
Overview of Single-Phase Grid-Connected Photovoltaic Systems
DEFF Research Database (Denmark)
Yang, Yongheng; Blaabjerg, Frede
2017-01-01
A continuous booming installation of solar photovoltaic (PV) systems has been witnessed worldwide. It is mainly driven by the imperative demand of “clean” power generation from renewables. Grid-connected PV systems will thus become an even more active player in the future mixed power systems, which...... systems. This chapter thus gives an overview of the advancement of power electronics converters in single-phase grid-connected PV systems, being commonly used in residential applications. Demands to single-phase grid-connected PV systems and the general control strategies are also addressed...... are linked together by a vast of power electronics converters and the power grid. In order to achieve a reliable and efficient power generation from PV systems, more stringent demands have been imposed on the entire PV system. It, in return, advances the development of the power converter technology in PV...
Polarization Dependence of Surface Enhanced Raman Scattering on a Single Dielectric Nanowire
Directory of Open Access Journals (Sweden)
Hua Qi
2012-01-01
Full Text Available Our measurements of surface enhanced Raman scattering (SERS on Ga2O3 dielectric nanowires (NWs core/silver composites indicate that the SERS enhancement is highly dependent on the polarization direction of the incident laser light. The polarization dependence of the SERS signal with respect to the direction of a single NW was studied by changing the incident light angle. Further investigations demonstrate that the SERS intensity is not only dependent on the direction and wavelength of the incident light, but also on the species of the SERS active molecule. The largest signals were observed on an NW when the incident 514.5 nm light was polarized perpendicular to the length of the NW, while the opposite phenomenon was observed at the wavelength of 785 nm. Our theoretical simulations of the polarization dependence at 514.5 nm and 785 nm are in good agreement with the experimental results.
Potenza, M A C; Krpetić, Ž; Sanvito, T; Cai, Q; Monopoli, M; de Araújo, J M; Cella, C; Boselli, L; Castagnola, V; Milani, P; Dawson, K A
2017-02-23
The shape and size of nanoparticles are important parameters affecting their biodistribution, bioactivity, and toxicity. The high-throughput characterisation of the nanoparticle shape in dispersion is a fundamental prerequisite for realistic in vitro and in vivo evaluation, however, with routinely available bench-top optical characterisation techniques, it remains a challenging task. Herein, we demonstrate the efficacy of a single particle extinction and scattering (SPES) technique for the in situ detection of the shape of nanoparticles in dispersion, applied to a small library of anisotropic gold particles, with a potential development for in-line detection. The use of SPES paves the way to the routine quantitative analysis of nanoparticles dispersed in biologically relevant fluids, which is of importance for the nanosafety assessment and any in vitro and in vivo administration of nanomaterials.
Proton resonance elastic scattering of $^{30}$Mg for single particle structure of $^{31}$Mg
The single particle structure of $^{31}$Mg, which is located in the so-called “island of inversion”, will be studied through measuring Isobaric Analog Resonances (IARs) of bound states of $^{31}$Mg. They are located in the high excitation energy of $^{31}$Al. We are going to determine the spectroscopic factors and angular momenta of the parent states by measuring the excitation function of the proton resonance elastic scattering around 0 degrees in the laboratory frame with around 3 MeV/nucleon $^{30}$Mg beam. The present study will reveal the shell evolution around $^{32}$Mg. In addition, the spectroscopic factor of the (7/2)$^{−}$ state which was not yet determined experimentally, may allow one to study the shape coexistence in this nucleus.
Finkelstein, N.; Gambogi, J.; Lempert, Walter R.; Miles, Richard B.; Rines, G. A.; Finch, A.; Schwarz, R. A.
1995-01-01
We present the development of a flexible, high power, narrow line width, tunable ultraviolet source for diagnostic application. By frequency tripling the output of a pulsed titanium-sapphire laser, we achieve broadly tunable (227-360 nm) ultraviolet light with high quality spatial and spectral resolution. We also present the characterization of a mercury vapor cell which provides a narrow band, sharp edge absorption filter at 253.7 nm. These two components form the basis for the extension of the Filtered Rayleigh Scattering technique into the ultraviolet. The UV-FRS system is comprised of four pieces: a single frequency, cw tunable Ti:Sapphire seeding source; a high-powered pulsed Ti:Sapphire oscillator; a third harmonic generator system; and an atomic mercury vapor filter. In this paper we discuss the development and characterization of each of these elements.
Valdés, Felipe
2013-03-01
Single-source time-domain electric-and magnetic-field integral equations for analyzing scattering from homogeneous penetrable objects are presented. Their temporal discretization is effected by using shifted piecewise polynomial temporal basis functions and a collocation testing procedure, thus allowing for a marching-on-in-time (MOT) solution scheme. Unlike dual-source formulations, single-source equations involve space-time domain operator products, for which spatial discretization techniques developed for standalone operators do not apply. Here, the spatial discretization of the single-source time-domain integral equations is achieved by using the high-order divergence-conforming basis functions developed by Graglia alongside the high-order divergence-and quasi curl-conforming (DQCC) basis functions of Valdés The combination of these two sets allows for a well-conditioned mapping from div-to curl-conforming function spaces that fully respects the space-mapping properties of the space-time operators involved. Numerical results corroborate the fact that the proposed procedure guarantees accuracy and stability of the MOT scheme. © 2012 IEEE.
Berry-phase blockade in single-molecule magnets
Gonzalez, Gabriel; Leuenberger, Michael N.
2006-01-01
We formulate the problem of electron transport through a single-molecule magnet (SMM) in the Coulomb blockade regime taking into account topological interference effects for the tunneling of the large spin of a SMM. The interference originates from spin Berry phases associated with different tunneling paths. We show that in the case of incoherent spin states it is essential to place the SMM between oppositely spin-polarized source and drain leads in order to detect the spin tunneling in the s...
Pettersson, Niklas; Wessman, Sten; Hertzman, Staffan; Studer, Andrew
2017-04-01
Duplex stainless steels are designed to solidify with ferrite as the parent phase, with subsequent austenite formation occurring in the solid state, implying that, thermodynamically, a fully ferritic range should exist at high temperatures. However, computational thermodynamic tools appear currently to overestimate the austenite stability of these systems, and contradictory data exist in the literature. In the present work, the high-temperature phase equilibria of four commercial duplex stainless steel grades, denoted 2304, 2101, 2507, and 3207, with varying alloying levels were assessed by measurements of the austenite-to-ferrite transformation at temperatures approaching 1673 K (1400 °C) using a novel in-situ neutron scattering approach. All grades became fully ferritic at some point during progressive heating. Higher austenite dissolution temperatures were measured for the higher alloyed grades, and for 3207, the temperature range for a single-phase ferritic structure approached zero. The influence of temperatures in the region of austenite dissolution was further evaluated by microstructural characterization using electron backscattered diffraction of isothermally heat-treated and quenched samples. The new experimental data are compared to thermodynamic calculations, and the precision of databases is discussed.
Exploring the bulk-phase structure of ionic liquid mixtures using small-angle neutron scattering.
Cabry, Christopher P; D'Andrea, Lucía; Shimizu, Karina; Grillo, Isabelle; Li, Peixun; Rogers, Sarah; Bruce, Duncan W; Canongia Lopes, José N; Slattery, John M
2018-01-01
Small-angle neutron scattering experiments, supported by molecular dynamics simulations, have been performed on a range of compositions of the [C 2 mim] 1-x [C 12 mim] x [Tf 2 N] ionic liquid mixture system. Isotopic contrast variation, through selective deuteration of both cations, has been used to assist in fitting the data to different scattering models. These data, and subsequent fitting, show that the structure of the ionic liquid mixtures changes substantially as a function of composition. Mixtures where x 0.32 can be described as bicontinuous, containing networks of both polar and non-polar domains, where the C12 chains of the [C 12 mim] + ions percolate through the system to form a continuous non-polar sub-phase. Temperature-dependent scattering experiments suggest that there is relatively little change in bulk structure in these liquids between 20 and 60 °C. The presence of water, however, does influence some aspects of the liquid structure in a composition that is rich in [C 2 mim][Tf 2 N] (where x = 0.24).
Ford, Kathleen M; Konzman, Brian G; Rubinson, Judith F
2011-12-15
Neutron scattering techniques have been used frequently to characterize geological specimens and to determine the structures of glasses and of polymers as solutions, suspensions, or melts. Little work has been reported on their application in determining polymers' structural properties relevant to separations. Here, we present a comparison of characterization results from nitrogen porosimetry and from combined small angle neutron scattering (SANS) and ultrasmall angle neutron scattering (USANS) experiments. We show that SANS is extremely sensitive to the pore characteristics. Both approaches can provide information about porosity and pore characteristics, but the neutron scattering techniques provide additional information in the form of the surface characteristics of the pores and their length scales. Fits of the scattering data show that cylindrical pores are present with diameters down to 0.6 μm and that, for length scales down to approxmately 20 Å, the material shows self-similar (fractal) slopes of -3.4 to -3.6. Comparison of these characteristics with other examples from the scattering literature indicate that further investigation of their meaning for chromatographic media is required.
DEFF Research Database (Denmark)
Qu, Hao; Yang, Xijun; Guo, Yougui
2014-01-01
Single-phase voltage source converter (VSC) is an important power electronic converter (PEC), including single-phase voltage source inverter (VSI), single-phase voltage source rectifier (VSR), single-phase active power filter (APF) and single-phase grid-connection inverter (GCI). Single-phase VSC...
Bidirectional reflectance spectroscopy 7. The single particle phase function hockey stick relation
Hapke, Bruce
2012-11-01
The measured volume-average single particle angular scattering functions of a large number of types of particle of interest for planetary regoliths in the visible-near-IR wavelength region can be represented to a reasonable approximation by two-parameter, double Henyey-Greenstein functions. When the two parameters of this function are plotted against one another they are found to be inversely correlated and lie within a restricted zone shaped like a hockey stick within the parameter space. The centroid of the zone is a curve that can be represented by a simple empirical equation. The wide variety of types of particles used to construct the plot implies that this equation may represent most of the particles found in regoliths. This means that when modeling the bidirectional reflectance of a regolith it may be possible to reduce the number of parameters necessary to specify the reflectance, and also to characterize the entire single particle phase function from observations at phase angles less than 90°. Even if the hockey stick relation has a finite width, rather than being a line, it restricts the parameter space that must be searched when fitting data. The curve should also be useful for forward modeling particle phase functions.
Jurna, M.; Garbacik, E.T.; Korterik, Jeroen P.; Herek, Jennifer Lynn; Otto, Cornelis; Offerhaus, Herman L.
2010-01-01
In coherent anti-Stokes Raman scattering (CARS), the emitted signal carries both amplitude and phase information of the molecules in the focal volume. Most CARS experiments ignore the phase component, but its detection allows for two advantages over intensity-only CARS. First, the pure resonant
Spectrometer for Particle Characterization With a New Multiple-Scattering Theory, Phase I
National Aeronautics and Space Administration — There are two major commercial types of light-scattering particle size analyzers: Static Light Scattering and Dynamic Light Scattering. They are expensive, delicate,...
Simulation of the phenomenon of single-phase and two-phase natural circulation
International Nuclear Information System (INIS)
Castrillo, Lazara Silveira
1998-02-01
Natural convection phenomenon is often used to remove the residual heat from the surfaces of bodies where the heat is generated e.g. during accidents or transients of nuclear power plants. Experimental study of natural circulation can be done in small scale experimental circuits and the results can be extrapolated for larger operational facilities. The numerical analysis of transients can be carried out by using large computational codes that simulate the thermohydraulic behavior in such facilities. The computational code RELAP5/MOD2, (Reactor Excursion and Leak Analysis Program) was developed by U.S. Nuclear Regulatory Commissions's. Division of Reactor Safety Research with the objective of analysis of transients and postulated accidents in the light water reactor (LWR) systems, including small and large ruptures with loss of coolant accidents (LOCA's). The results obtained by the simulation of single-phase and two-phase natural circulation, using the RELAP5/MOD2, are presented in this work. The study was carried out using the experimental circuit built at the 'Departamento de Engenharia Quimica da Escola Politecnica da Universidade de Sao Paulo'. In the circuit, two experiments were carried out with different conditions of power and mass flow, obtaining a single-phase regime with a level of power of 4706 W and flow of 5.10 -5 m 3 /s (3 l/min) and a two-phase regime with a level of power of 6536 W and secondary flow 2,33.10 -5 m 3 /s (1,4 l/min). The study allowed tio evaluate the capacity of the code for representing such phenomena as well as comparing the transients obtained theoretically with the experimental results. The comparative analysis shows that the code represents fairly well the single-phase transient, but the results for two-phase transients, starting from the nodalization and calibration used for the case single-phase transient, did not reproduce faithfully some experimental results. (author)
Gorfman, Semën; Keeble, Dean S; Bombardi, Alessandro; Thomas, Pam A
2015-10-01
The results of high-resolution measurements of the diffuse X-ray scattering produced by a perovskite-based Na 0.5 Bi 0.5 TiO 3 ferroelectric single crystal between 40 and 620 K are reported. The study was designed as an attempt to resolve numerous controversies regarding the average structure of Na 0.5 Bi 0.5 TiO 3 , such as the mechanism of the phase transitions between the tetragonal, P 4 bm , and rhombohedral | monoclinic, R 3 c | Cc , space groups and the correlation between structural changes and macroscopic physical properties. The starting point was to search for any transformations of structural disorder in the temperature range of thermal depoling (420-480 K), where the average structure is known to remain unchanged. The intensity distribution around the {032} pseudocubic reflection was collected using a PILATUS 100K detector at the I16 beamline of the Diamond Light Source (UK). The data revealed previously unknown features of the diffuse scattering, including a system of dual asymmetric L-shaped diffuse scattering streaks. The topology, temperature dependence, and relationship between Bragg and diffuse intensities suggest the presence of complex microstructure in the low-temperature R 3 c | Cc phase. This microstructure may be formed by the persistence of the higher-temperature P 4 bm phase, built into a lower-temperature R 3 c | Cc matrix, accompanied by the related long-range strain fields. Finally, it is shown that a correlation between the temperature dependence of the X-ray scattering features and the temperature regime of thermal depoling is present.
Energy Technology Data Exchange (ETDEWEB)
Arnecke, Florian
2009-01-19
In this thesis we have studied the threshold behaviour od scattering phases in attactive, singular potentials proportional to -1/r{sup {alpha}}, {alpha}>2, in two and three dimensions. Total absorption on the surface was described by incoming boundary condition in form of WKB waves, so that the scattering phase {delta}(k) is because of the particle loss a complex quantity and the S matrix no longer unitary. As application example we use the scattering behaviour of ultracold atoms on an absorbing sphere. The parameters were so chosen that they correspond to those of metastable helium (2{sup 3}S) atoms respectively sodium atoms in the ground state and a radius of the sphere of 200 respectively 2000 a. u. The final chapter presents a survey about the scattering on a circularly symmetric potential in two dimensions.
Aoun, Bachir; Pellegrini, Eric; Trapp, Marcus; Natali, Francesca; Cantù, Laura; Brocca, Paola; Gerelli, Yuri; Demé, Bruno; Marek Koza, Michael; Johnson, Mark; Peters, Judith
2016-04-01
Neutron scattering techniques have been employed to investigate 1,2-dimyristoyl-sn -glycero-3-phosphocholine (DMPC) membranes in the form of multilamellar vesicles (MLVs) and deposited, stacked multilamellar-bilayers (MLBs), covering transitions from the gel to the liquid phase. Neutron diffraction was used to characterise the samples in terms of transition temperatures, whereas elastic incoherent neutron scattering (EINS) demonstrates that the dynamics on the sub-macromolecular length-scale and pico- to nano-second time-scale are correlated with the structural transitions through a discontinuity in the observed elastic intensities and the derived mean square displacements. Molecular dynamics simulations have been performed in parallel focussing on the length-, time- and temperature-scales of the neutron experiments. They correctly reproduce the structural features of the main gel-liquid phase transition. Particular emphasis is placed on the dynamical amplitudes derived from experiment and simulations. Two methods are used to analyse the experimental data and mean square displacements. They agree within a factor of 2 irrespective of the probed time-scale, i.e. the instrument utilized. Mean square displacements computed from simulations show a comparable level of agreement with the experimental values, albeit, the best match with the two methods varies for the two instruments. Consequently, experiments and simulations together give a consistent picture of the structural and dynamical aspects of the main lipid transition and provide a basis for future, theoretical modelling of dynamics and phase behaviour in membranes. The need for more detailed analytical models is pointed out by the remaining variation of the dynamical amplitudes derived in two different ways from experiments on the one hand and simulations on the other.
International Nuclear Information System (INIS)
Helgesen, G.; Hill, J.P.; Thurston, T.R.; Gibbs, D.
1995-01-01
We present resonant x-ray magnetic scattering studies of the temperature dependence of the magnetic order parameters of Dy, Ho, Er, and Tm single crystals near their antiferromagnetic phase transitions. The experimentally determined values of the critical exponent β of Er and Tm, which have c-axis modulated structures, are nearly equal and consistent with the mean-field value (β=0.47±0.05 and β=0.49±0.06, respectively). The measured values of Dy and Ho, which have spiral magnetic structures, are lower (β=0.36±0.04 and β=0.41±0.04, respectively). In addition to the primary magnetic order parameters, we have measured the temperature dependence of the intensities of up to four higher harmonics. The exponents of the higher harmonic satellites of Er and Tm exhibit mean-field-like scaling, while those of Ho do not. We discuss these results within the context of simple corrections to mean-field scaling, based on the three-dimensional XY model. We also report measurements of the temperature dependence of the c-axis lattice constants and magnetic wave vectors of all four metals. It is found that the magnetic correlation lengths are reduced near transitions to ferrimagnetic and ferromagnetic phases
Tao, Zongming; Liu, Dong; Wang, Zhenzhu; Ma, Xiaomin; Zhang, Qingze; Xie, Chenbo; Bo, Guangyu; Hu, Shunxing; Wang, Yingjian
2014-01-13
By using a charge-coupled device (CCD) as the detector, side-scatter lidar has great potential applications in the near range atmospheric detection. A new inversion method is proposed for CCD side-scatter lidar (Clidar) to retrieve aerosol phase function and vertical backscattering coefficient. Case studies show the retrieved results from Clidar are in good agreements with those obtained from other instruments. It indicates that the new proposed inversion method is reliable and feasible and that the Clidar is practicable.
Berry-Phase Blockade in Single-Molecule Magnets
González, Gabriel; Leuenberger, Michael N.
2007-06-01
We formulate the problem of electron transport through a single-molecule magnet (SMM) in the Coulomb blockade regime taking into account topological interference effects for the tunneling of the large spin of a SMM. The interference originates from spin Berry phases associated with different tunneling paths. We show that, in the case of incoherent spin states, it is essential to place the SMM between oppositely spin-polarized source and drain leads in order to detect the spin tunneling in the stationary current, which exhibits topological zeros as a function of the transverse magnetic field.
Solution Concept of Modular Single Phase Active Power Filters
Directory of Open Access Journals (Sweden)
Marek Roch
2006-01-01
Full Text Available This paper investigates a modular or a decentralised single-phase active power filter control strategy. It is based on the evaluation of the harmonic reference load currents for the active power filter blocks operating under specific harmonic frequencies. The underlying principle of the modular active power filter is explained and it is shown how the required reference harmonic currents can be evaluated. Simulation results demonstrated the improvement in the dynamic performance of the modular active power filter presented here in comparison with the conventional type.
A Transformer-less Single Phase Inverter For photovoltaic Systems
DEFF Research Database (Denmark)
Mostaan, Ali; Alizadeh, Ebrahim; Qu, Ying
2017-01-01
A single phase transformer-less inverter is introduced in this paper. The negative polarities of the input voltage and output terminal have common ground. Therefore, the leakage current problem that is common in PV systems is eliminated naturally. In addition, the proposed inverter has fewer...... components compared with its counterparts and only one switch conducts during the active states which enhance the inverter efficiency. The proposed inverter is analyzed in details and compared with some existing topologies. The performance of the proposed inverter is validated using the simulation results....
International Nuclear Information System (INIS)
Dahmen, Bernd
1994-01-01
A systematic method to obtain strong coupling expansions for scattering quantities in hamiltonian lattice field theories is presented. I develop the conceptual ideas for the case of the hamiltonian field theory analogue of the Ising model, in d space and one time dimension. The main result is a convergent series representation for the scattering states and the transition matrix. To be explicit, the special cases of d=1 and d=3 spatial dimensions are discussed in detail. I compute the next-to-leading order approximation for the phase shifts. The application of the method to investigate low-energy scattering phenomena in lattice gauge theory and QCD is proposed. ((orig.))
Simulation of single grid-based phase-contrast x-ray imaging (g-PCXI)
Energy Technology Data Exchange (ETDEWEB)
Lim, H.W.; Lee, H.W. [Department of Radiation Convergence Engineering, iTOMO Group, Yonsei University, 1 Yonseidae-gil, Wonju, Gangwon-do 26493 (Korea, Republic of); Cho, H.S., E-mail: hscho1@yonsei.ac.kr [Department of Radiation Convergence Engineering, iTOMO Group, Yonsei University, 1 Yonseidae-gil, Wonju, Gangwon-do 26493 (Korea, Republic of); Je, U.K.; Park, C.K.; Kim, K.S.; Kim, G.A.; Park, S.Y.; Lee, D.Y.; Park, Y.O.; Woo, T.H. [Department of Radiation Convergence Engineering, iTOMO Group, Yonsei University, 1 Yonseidae-gil, Wonju, Gangwon-do 26493 (Korea, Republic of); Lee, S.H.; Chung, W.H.; Kim, J.W.; Kim, J.G. [R& D Center, JPI Healthcare Co., Ltd., Ansan 425-833 (Korea, Republic of)
2017-04-01
Single grid-based phase-contrast x-ray imaging (g-PCXI) technique, which was recently proposed by Wen et al. to retrieve absorption, scattering, and phase-gradient images from the raw image of the examined object, seems a practical method for phase-contrast imaging with great simplicity and minimal requirements on the setup alignment. In this work, we developed a useful simulation platform for g-PCXI and performed a simulation to demonstrate its viability. We also established a table-top setup for g-PCXI which consists of a focused-linear grid (200-lines/in strip density), an x-ray tube (100-μm focal spot size), and a flat-panel detector (48-μm pixel size) and performed a preliminary experiment with some samples to show the performance of the simulation platform. We successfully obtained phase-contrast x-ray images of much enhanced contrast from both the simulation and experiment and the simulated contract seemed similar to the experimental contrast, which shows the performance of the developed simulation platform. We expect that the simulation platform will be useful for designing an optimal g-PCXI system. - Highlights: • It is proposed for the single grid-based phase-contrast x-ray imaging (g-PCXI) technique. • We implemented for a numerical simulation code. • The preliminary experiment with several samples to compare is performed. • It is expected to be useful to design an optimal g-PCXI system.
Energy Technology Data Exchange (ETDEWEB)
Wang, Hongchang, E-mail: hongchang.wang@diamond.ac.uk; Kashyap, Yogesh; Sawhney, Kawal [Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE (United Kingdom)
2016-03-21
X-ray dark-field contrast tomography can provide important supplementary information inside a sample to the conventional absorption tomography. Recently, the X-ray speckle based technique has been proposed to provide qualitative two-dimensional dark-field imaging with a simple experimental arrangement. In this letter, we deduce a relationship between the second moment of scattering angle distribution and cross-correlation degradation of speckle and establish a quantitative basis of X-ray dark-field tomography using single directional speckle scanning technique. In addition, the phase contrast images can be simultaneously retrieved permitting tomographic reconstruction, which yields enhanced contrast in weakly absorbing materials. Such complementary tomography technique can allow systematic investigation of complex samples containing both soft and hard materials.
Hybrid Three-Phase/Single-Phase Microgrid Architecture with Power Management Capabilities
DEFF Research Database (Denmark)
Sun, Qiuye; Zhou, Jianguo; Guerrero, Josep M.
2015-01-01
With the fast proliferation of single-phase distributed generation (DG) units and loads integrated into residential microgrids, independent power sharing per phase and full use of the energy generated by DGs have become crucial. To address these issues, this paper proposes a hybrid microgrid...... control of load power sharing among phases, as well as to allow fully utilization of the energy generated by DGs. Meanwhile, the method combining the modified adaptive backstepping-sliding mode control approach and droop control is also proposed to design the SPBTB system controllers. With the application...... of the proposed PSU and its power management strategy, the loads among different phases can be properly supplied and the energy can be fully utilized as well as obtaining better load sharing. Simulation and experimental results are provided to demonstrate the validity of the proposed hybrid microgrid structure...
Ouyang, Wei; Mao, Weijian
2018-03-01
An asymptotic quadratic true-amplitude inversion method for isotropic elastic P waves is proposed to invert medium parameters. The multicomponent P-wave scattered wavefield is computed based on a forward relationship using second-order Born approximation and corresponding high-frequency ray theoretical methods. Within the local double scattering mechanism, the P-wave transmission factors are elaborately calculated, which results in the radiation pattern for P-waves scattering being a quadratic combination of the density and Lamé's moduli perturbation parameters. We further express the elastic P-wave scattered wavefield in a form of generalized Radon transform (GRT). After introducing classical backprojection operators, we obtain an approximate solution of the inverse problem by solving a quadratic non-linear system. Numerical tests with synthetic data computed by finite-differences scheme demonstrate that our quadratic inversion can accurately invert perturbation parameters for strong perturbations, compared with the P-wave single-scattering linear inversion method. Although our inversion strategy here is only syncretized with P-wave scattering, it can be extended to invert multicomponent elastic data containing both P-wave and S-wave information.
Directory of Open Access Journals (Sweden)
Pedro Samuel Gomes Medeiros
2011-09-01
Full Text Available This paper makes a comparative analysis of the thermophysical properties of ice slurry with conventional single-phase secondary fluids used in thermal storage cooling systems. The ice slurry is a two-phase fluid consisting of water, antifreeze and ice crystals. It is a new technology that has shown great energy potential. In addition to transporting energy as a heat transfer fluid, it has thermal storage properties due to the presence of ice, storing coolness by latent heat of fusion. The single-phase fluids analyzed are water-NaCl and water-propylene glycol solutions, which also operate as carrier fluids in ice slurry. The presence of ice changes the thermophysical properties of aqueous solutions and a number of these properties were determined: density, thermal conductivity and dynamic viscosity. Data were obtained by software simulation. The results show that the presence of 10% by weight of ice provides a significant increase in thermal conductivity and dynamic viscosity, without causing changes in density. The rheological behavior of ice slurries, associated with its high viscosity, requires higher pumping power; however, this was not significant because higher thermal conductivity allows a lower mass flow rate without the use of larger pumps. Thus, the ice slurry ensures its high potential as a secondary fluid in thermal storage cooling systems, proving to be more efficient than single-phase secondary fluids.
Synthesis and magnetic properties of single phase titanomagnetites
Energy Technology Data Exchange (ETDEWEB)
Schoenthal, W., E-mail: wms@andrew.cmu.edu; Liu, X.; Cox, T.; Laughlin, D. E.; McHenry, M. E. [Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States); Mesa, J. L.; Diaz-Michelena, M. [Instituto Nacional de Tecnica Aeroespacial, Madrid (Spain); Maicas, M. [Universidad Politecnica de Madrid, ISOM-ETSIT, Madrid (Spain)
2014-05-07
The focus of this paper is the study of cation distributions and resulting magnetizations in titanomagnetites (TMs), (1−x)Fe{sub 3}O{sub 4−x}Fe{sub 2}TiO{sub 4} solid solutions. TM remnant states are hypothesized to contribute to planetary magnetic field anomalies. This work correlates experimental data with proposed models for the TM pseudobinary. Improved synthesis procedures are reported for single phase Ulvöspinel (Fe{sub 2}TiO{sub 4}), and TM solid solutions were made using solid state synthesis techniques. X-ray diffraction and scanning electron microscopy show samples to be single phase solid solutions. M-H curves of TM75, 80, 85, 90, and 95 (TMX where X = at. % of ulvöspinel) were measured using a Physical Property Measurement System at 10 K, in fields of 0 to 8 T. The saturation magnetization was found to be close to that predicted by the Neel model for cation distribution in TMs. M-T curves of the remnant magnetization were measured from 10 K to 350 K. The remnant magnetization was acquired at 10 K by applying an 8 T field and then releasing the field. Experimental Neel temperatures are reported for samples in the Neel model ground state.
The Interplay of Symmetry and Scattering Phase in Second Harmonic Generation from Gold Nanoantennas.
Gennaro, Sylvain D; Rahmani, Mohsen; Giannini, Vincenzo; Aouani, Heykel; Sidiropoulos, Themistoklis P H; Navarro-Cía, Miguel; Maier, Stefan A; Oulton, Rupert F
2016-08-10
Nonlinear phenomena are central to modern photonics but, being inherently weak, typically require gradual accumulation over several millimeters. For example, second harmonic generation (SHG) is typically achieved in thick transparent nonlinear crystals by phase-matching energy exchange between light at initial, ω, and final, 2ω, frequencies. Recently, metamaterials imbued with artificial nonlinearity from their constituent nanoantennas have generated excitement by opening the possibility of wavelength-scale nonlinear optics. However, the selection rules of SHG typically prevent dipole emission from simple nanoantennas, which has led to much discussion concerning the best geometries, for example, those breaking centro-symmetry or incorporating resonances at multiple harmonics. In this work, we explore the use of both nanoantenna symmetry and multiple harmonics to control the strength, polarization and radiation pattern of SHG from a variety of antenna configurations incorporating simple resonant elements tuned to light at both ω and 2ω. We use a microscopic description of the scattering strength and phases of these constituent particles, determined by their relative positions, to accurately predict the SHG radiation observed in our experiments. We find that the 2ω particles radiate dipolar SHG by near-field coupling to the ω particle, which radiates SHG as a quadrupole. Consequently, strong linearly polarized dipolar SHG is only possible for noncentro-symmetric antennas that also minimize interference between their dipolar and quadrupolar responses. Metamaterials with such intra-antenna phase and polarization control could enable compact nonlinear photonic nanotechnologies.
Zhao, Feng; Zou, Kai; Shang, Hong; Ji, Zheng; Zhao, Huijie; Huang, Wenjiang; Li, Cunjun
2010-10-01
In this paper we present an analytical model for the computation of radiation transfer of discontinuous vegetation canopies. Some initial results of gap probability and bidirectional gap probability of discontinuous vegetation canopies, which are important parameters determining the radiative environment of the canopies, are given and compared with a 3- D computer simulation model. In the model, negative exponential attenuation of light within individual plant canopies is assumed. Then the computation of gap probability is resolved by determining the entry points and exiting points of the ray with the individual plants via their equations in space. For the bidirectional gap probability, which determines the single-scattering contribution of the canopy, a gap statistical analysis based model was adopted to correct the dependence of gap probabilities for both solar and viewing directions. The model incorporates the structural characteristics, such as plant sizes, leaf size, row spacing, foliage density, planting density, leaf inclination distribution. Available experimental data are inadequate for a complete validation of the model. So it was evaluated with a three dimensional computer simulation model for 3D vegetative scenes, which shows good agreement between these two models' results. This model should be useful to the quantification of light interception and the modeling of bidirectional reflectance distributions of discontinuous canopies.
Huang, Bin; Yan, Shuai; Xiao, Lin; Ji, Rong; Yang, Liuyan; Miao, Ai-Jun; Wang, Ping
2018-03-01
Imaging and quantification of nanoparticles in single cells in their most natural condition are expected to facilitate the biotechnological applications of nanoparticles and allow for better assessment of their biosafety risks. However, current imaging modalities either require tedious sample preparation or only apply to nanoparticles with specific physicochemical characteristics. Here, the emerging hyperspectral stimulated Raman scattering (SRS) microscopy, as a label-free and nondestructive imaging method, is used for the first time to investigate the subcellular distribution of nanoparticles in the protozoan Tetrahymena thermophila. The two frequently studied nanoparticles, polyacrylate-coated α-Fe 2 O 3 and TiO 2 , are found to have different subcellular distribution pattern as a result of their dissimilar uptake routes. Significant uptake competition between these two types of nanoparticles is further discovered, which should be paid attention to in future bioapplications of nanoparticles. Overall, this study illustrates the great promise of hyperspectral SRS as an analytical imaging tool in nanobiotechnology and nanotoxicology. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Directory of Open Access Journals (Sweden)
Y. Sakai
2017-06-01
Full Text Available Inverse Compton scattering (ICS is a unique mechanism for producing fast pulses—picosecond and below—of bright photons, ranging from x to γ rays. These nominally narrow spectral bandwidth electromagnetic radiation pulses are efficiently produced in the interaction between intense, well-focused electron and laser beams. The spectral characteristics of such sources are affected by many experimental parameters, with intense laser effects often dominant. A laser field capable of inducing relativistic oscillatory motion may give rise to harmonic generation and, importantly for the present work, nonlinear redshifting, both of which dilute the spectral brightness of the radiation. As the applications enabled by this source often depend sensitively on its spectra, it is critical to resolve the details of the wavelength and angular distribution obtained from ICS collisions. With this motivation, we present an experimental study that greatly improves on previous spectral measurement methods based on x-ray K-edge filters, by implementing a multilayer bent-crystal x-ray spectrometer. In tandem with a collimating slit, this method reveals a projection of the double differential angular-wavelength spectrum of the ICS radiation in a single shot. The measurements enabled by this diagnostic illustrate the combined off-axis and nonlinear-field-induced redshifting in the ICS emission process. The spectra obtained illustrate in detail the strength of the normalized laser vector potential, and provide a nondestructive measure of the temporal and spatial electron-laser beam overlap.
Single phase and two-phase flow pressure losses through restrictions, expansions and inserts
International Nuclear Information System (INIS)
Glenat, P.; Solignac, P.
1984-11-01
We give a selection of methods to predict pressure losses through retrictions, expansions and inserts. In single phase flow, we give the classical method based on the one-dimensional momentum and mass balances. In two-phase flow, we propose the method given by Harshe et al. and an empirical approach suggested by Chisholm. We notice the distinction between long and short inserts depends upon wether or not the vena contracta lies within insert. Finally, we propose three correlations to calculate void fraction through the singularities which have been considered [fr
Geilhufe, Matthias; Achilles, Steven; Köbis, Markus Arthur; Arnold, Martin; Mertig, Ingrid; Hergert, Wolfram; Ernst, Arthur
2015-11-01
For a reliable fully-relativistic Korringa-Kohn-Rostoker Green function method, an accurate solution of the underlying single-site scattering problem is necessary. We present an extensive discussion on numerical solutions of the related differential equations by means of standard methods for a direct solution and by means of integral equations. Our implementation is tested and exemplarily demonstrated for a spherically symmetric treatment of a Coulomb potential and for a Mathieu potential to cover the full-potential implementation. For the Coulomb potential we include an analytic discussion of the asymptotic behaviour of irregular scattering solutions close to the origin (r\\ll 1 ).
Energy Technology Data Exchange (ETDEWEB)
Garvey, G. T. [Los Alamos; Harris, D. A. [Fermilab; Tanaka, H. A. [British Columbia U.; Tayloe, R. [Indiana U.; Zeller, G. P. [Fermilab
2015-06-15
The study of neutrino–nucleus interactions has recently seen rapid development with a new generation of accelerator-based neutrino experiments employing medium and heavy nuclear targets for the study of neutrino oscillations. A few unexpected results in the study of quasi-elastic scattering and single photon production have spurred a revisiting of the underlying nuclear physics and connections to electron–nucleus scattering. A thorough understanding and resolution of these issues is essential for future progress in the study of neutrino oscillations.
International Nuclear Information System (INIS)
Choi, Han Kyu; Kim, Zee Hwan
2015-01-01
The electromagnetic (EM) enhancement mechanism of surface-enhanced Raman scattering (SERS) has been well established through 30 years of extensive investigation: molecules adsorbed on resonantly driven silver or gold nanoparticles (NPs) experience strongly enhanced field and thus show enhanced Raman scattering. Even stronger SERS enhancement is possible with a gap structure in which two or more NPs form assemblies with gap sizes of 1 nm or less. We have theoretically shown that the measurement of SERS angular distribution can reveal the position of a single molecule near the gap with 1-nm accuracy, even though the spatial extent of the enhanced field is ~10 nm. Real implementation of such experiment requires extremely well-defined (preferably a single crystal) dimeric junctions. Nevertheless, the experiment will provide spatial as well as frequency domain information on single-molecule dynamics at metallic surfaces
Reducing Electromagnetic Interference in a Grid Tied Single Phase Power Inverter
2016-09-01
ELECTROMAGNETIC INTERFERENCE IN A GRID TIED SINGLE PHASE POWER INVERTER by Jason Hassan Valiani September 2016 Thesis Advisor: Giovanna Oriti...3. REPORT TYPE AND DATES COVERED Master’s thesis 4. TITLE AND SUBTITLE REDUCING ELECTROMAGNETIC INTERFERENCE IN A GRID TIED SINGLE PHASE POWER...The addition of a passive filter proved to minimize the conducted EMI for a single -phase grid-tied inverter. 14. SUBJECT TERMS single -phase
Equivalence of two models in single-phase multicomponent flow simulations
Wu, Yuanqing
2016-02-28
In this work, two models to simulate the single-phase multicomponent flow in reservoirs are introduced: single-phase multicomponent flow model and two-phase compositional flow model. Because the single-phase multicomponent flow is a special case of the two-phase compositional flow, the two-phase compositional flow model can also simulate the case. We compare and analyze the two models when simulating the single-phase multicomponent flow, and then demonstrate the equivalence of the two models mathematically. An experiment is also carried out to verify the equivalence of the two models.
Retrievals and uncertainty analysis of aerosol single scattering albedo from MFRSR measurements
International Nuclear Information System (INIS)
Yin, Bangsheng; Min, Qilong; Joseph, Everette
2015-01-01
Aerosol single scattering albedo (SSA) can be retrieved from the ratio of diffuse horizontal and direct normal fluxes measured from multifilter rotating shadowband radiometer (MFRSR). In this study, the measurement channels at 415 nm and 870 nm are selected for aerosol optical depth (AOD) and Angstrom coefficient retrievals, and the measurements at 415 nm are used for aerosol SSA retrievals with the constraint of retrieved Angstrom coefficient. We extensively assessed various issues impacting on the accuracy of SSA retrieval from measurements to input parameters and assumptions. For cloud-free days with mean aerosol loading of 0.13–0.60, our sensitivity study indicated that: (1) 1% calibration uncertainty can result in 0.8–3.7% changes in retrieved SSA; (2) without considering the cosine respond correction and/or forward scattering correction will result in underestimation of 1.1–3.3% and/or 0.73% in retrieved SSA; (3) an overestimation of 0.1 in asymmetry factor can result in an underestimation of 2.54–3.4% in retrieved SSA; (4) for small aerosol loading (e.g., 0.13), the uncertainty associated with the choice of Rayleigh optical depth value can result in non-negligible change in retrieved SSA (e.g., 0.015); (5) an uncertainty of 0.05 for surface albedo can result in changes of 1.49–5.4% in retrieved SSA. We applied the retrieval algorithm to the MFRSR measurements at the Atmospheric Radiation Measurements (ARM) Southern Great Plains (SGP) site. The retrieved results of AOD, Angstrom coefficient, and SSA are basically consistent with other independent measurements from co-located instruments at the site. - Highlights: • Aerosol SSA is derived from MFRSR measured diffuse to direct normal irradiance ratio. • We extensively assessed various issues impacting on the accuracy of SSA retrieval. • The issues are mainly from measurements and model input parameters and assumptions. • We applied the retrieval algorithm to the MFRSR measurements at ARM SGP
Wang, Xu; Gao, Zhensen; Kataoka, Nobuyuki; Wada, Naoya
2010-05-10
A novel scheme using single phase modulator for simultaneous time domain spectral phase encoding (SPE) signal generation and DPSK data modulation is proposed and experimentally demonstrated. Array- Waveguide-Grating and Variable-Bandwidth-Spectrum-Shaper based devices can be used for decoding the signal directly in spectral domain. The effects of fiber dispersion, light pulse width and timing error on the coding performance have been investigated by simulation and verified in experiment. In the experiment, SPE signal with 8-chip, 20GHz/chip optical code patterns has been generated and modulated with 2.5 Gbps DPSK data using single modulator. Transmission of the 2.5 Gbps data over 34km fiber with BEROCDMA) and secure optical communication applications. (c) 2010 Optical Society of America.
Aerosol single-scattering albedo retrieval over North Africa using critical reflectance
Wells, Kelley C.
The sign and magnitude of the aerosol radiative forcing over bright surfaces is highly dependent on the absorbing properties of the aerosol. Thus, the determination of aerosol forcing over desert regions requires accurate information about the aerosol single-scattering albedo (SSA). However, the brightness of desert surfaces complicates the retrieval of aerosol optical properties using passive space-based measurements. The aerosol critical reflectance is one parameter that can be used to relate top-of-atmosphere (TOA) reflectance changes over land to the aerosol absorption properties, without knowledge of the underlying surface properties or aerosol loading. Physically, the parameter represents the TOA reflectance at which increased aerosol scattering due to increased aerosol loading is balanced by increased absorption of the surface contribution to the TOA reflectance. It can be derived by comparing two satellite images with different aerosol loading, assuming that the surface reflectance and background aerosol are similar between the two days. In this work, we explore the utility of the critical reflectance method for routine monitoring of spectral aerosol absorption from space over North Africa, a region that is predominantly impacted by absorbing dust and biomass burning aerosol. We derive the critical reflectance from Moderate Resolution Spectroradiometer (MODIS) Level 1B reflectances in the vicinity of two Aerosol Robotic Network (AERONET) stations: Tamanrasset, a site in the Algerian Sahara, and Banizoumbou, a Sahelian site in Niger. We examine the sensitivity of the critical reflectance parameter to aerosol physical and optical properties, as well as solar and viewing geometry, using the Santa Barbara DISORT Radiative Transfer (SBDART) model, and apply our findings to retrieve SSA from the MODIS critical reflectance values. We compare our results to AERONET-retrieved estimates, as well as to measurements of the TOA albedo and surface fluxes from the
Simplified paraboloid phase model-based phase tracker for demodulation of a single complex fringe.
He, A; Deepan, B; Quan, C
2017-09-01
A regularized phase tracker (RPT) is an effective method for demodulation of single closed-fringe patterns. However, lengthy calculation time, specially designed scanning strategy, and sign-ambiguity problems caused by noise and saddle points reduce its effectiveness, especially for demodulating large and complex fringe patterns. In this paper, a simplified paraboloid phase model-based regularized phase tracker (SPRPT) is proposed. In SPRPT, first and second phase derivatives are pre-determined by the density-direction-combined method and discrete higher-order demodulation algorithm, respectively. Hence, cost function is effectively simplified to reduce the computation time significantly. Moreover, pre-determined phase derivatives improve the robustness of the demodulation of closed, complex fringe patterns. Thus, no specifically designed scanning strategy is needed; nevertheless, it is robust against the sign-ambiguity problem. The paraboloid phase model also assures better accuracy and robustness against noise. Both the simulated and experimental fringe patterns (obtained using electronic speckle pattern interferometry) are used to validate the proposed method, and a comparison of the proposed method with existing RPT methods is carried out. The simulation results show that the proposed method has achieved the highest accuracy with less computational time. The experimental result proves the robustness and the accuracy of the proposed method for demodulation of noisy fringe patterns and its feasibility for static and dynamic applications.
Characterization of single particle aerosols by elastic light scattering at multiple wavelengths
Lane, P. A.; Hart, M. B.; Jain, V.; Tucker, J. E.; Eversole, J. D.
2018-03-01
We describe a system to characterize individual aerosol particles using stable and repeatable measurement of elastic light scattering. The method employs a linear electrodynamic quadrupole (LEQ) particle trap. Charged particles, continuously injected by electrospray into this system, are confined to move vertically along the stability line in the center of the LEQ past a point where they are optically interrogated. Light scattered in the near forward direction was measured at three different wavelengths using time-division multiplexed collinear laser beams. We validated our method by comparing measured silica microsphere data for four selected diameters (0.7, 1.0, 1.5 and 2.0 μm) to a model of collected scattered light intensities based upon Lorenz-Mie scattering theory. Scattered light measurements at the different wavelengths are correlated, allowing us to distinguish and classify inhomogeneous particles.
Single Photon Sensitive HgCdTe Avalanche Photodiode Detector (APD), Phase II
National Aeronautics and Space Administration — Leveraging Phase I SBIR successes, in Phase II, a single photon sensitive LIDAR receiver will be fabricated and delivered to NASA. In Phase I, high-gain,...
MECHANICAL CHARACTERISTICS OF THREE-PHASE INDUCTION MOTORS WITH SINGLE-PHASE POWER SUPPLY
Directory of Open Access Journals (Sweden)
V.S. Malyar
2016-06-01
Full Text Available Aim. Development of a method for calculating mechanical characteristics of three-phase induction motors with single-phase power supply. Methods. The developed algorithm is based on the high-adequacy mathematical model of motor and projection method for solving the boundary problem for equations of electrical circuits balance presented in the three-phase coordinate system. As a result of asymmetry of power supply to the stator windings, in steady state, flux-linkage and current change according to the periodic law. They are determined by solving the boundary problem. Results. The developed mathematical model allows determining periodic dependence of coordinates as a function of slip and, based on them, mechanical characteristics of motors. Academic novelty. The developed method relies on a completely new mathematical approach to calculation of stationary modes of nonlinear electromagnetic circuits, which allows obtaining periodic solution in a timeless domain. Practical value. Using the developed calculation algorithm, one can select capacitance required to start an induction motor with single-phase power supply and calculate static mechanical characteristics at a given capacitance.
Energy Technology Data Exchange (ETDEWEB)
Min, Jonghwan; Pua, Rizza; Cho, Seungryong, E-mail: scho@kaist.ac.kr [Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 305-701 (Korea, Republic of); Kim, Insoo; Han, Bumsoo [EB Tech, Co., Ltd., 550 Yongsan-dong, Yuseong-gu, Daejeon 305-500 (Korea, Republic of)
2015-11-15
Purpose: A beam-blocker composed of multiple strips is a useful gadget for scatter correction and/or for dose reduction in cone-beam CT (CBCT). However, the use of such a beam-blocker would yield cone-beam data that can be challenging for accurate image reconstruction from a single scan in the filtered-backprojection framework. The focus of the work was to develop an analytic image reconstruction method for CBCT that can be directly applied to partially blocked cone-beam data in conjunction with the scatter correction. Methods: The authors developed a rebinned backprojection-filteration (BPF) algorithm for reconstructing images from the partially blocked cone-beam data in a circular scan. The authors also proposed a beam-blocking geometry considering data redundancy such that an efficient scatter estimate can be acquired and sufficient data for BPF image reconstruction can be secured at the same time from a single scan without using any blocker motion. Additionally, scatter correction method and noise reduction scheme have been developed. The authors have performed both simulation and experimental studies to validate the rebinned BPF algorithm for image reconstruction from partially blocked cone-beam data. Quantitative evaluations of the reconstructed image quality were performed in the experimental studies. Results: The simulation study revealed that the developed reconstruction algorithm successfully reconstructs the images from the partial cone-beam data. In the experimental study, the proposed method effectively corrected for the scatter in each projection and reconstructed scatter-corrected images from a single scan. Reduction of cupping artifacts and an enhancement of the image contrast have been demonstrated. The image contrast has increased by a factor of about 2, and the image accuracy in terms of root-mean-square-error with respect to the fan-beam CT image has increased by more than 30%. Conclusions: The authors have successfully demonstrated that the
Min, Jonghwan; Pua, Rizza; Kim, Insoo; Han, Bumsoo; Cho, Seungryong
2015-11-01
A beam-blocker composed of multiple strips is a useful gadget for scatter correction and/or for dose reduction in cone-beam CT (CBCT). However, the use of such a beam-blocker would yield cone-beam data that can be challenging for accurate image reconstruction from a single scan in the filtered-backprojection framework. The focus of the work was to develop an analytic image reconstruction method for CBCT that can be directly applied to partially blocked cone-beam data in conjunction with the scatter correction. The authors developed a rebinned backprojection-filteration (BPF) algorithm for reconstructing images from the partially blocked cone-beam data in a circular scan. The authors also proposed a beam-blocking geometry considering data redundancy such that an efficient scatter estimate can be acquired and sufficient data for BPF image reconstruction can be secured at the same time from a single scan without using any blocker motion. Additionally, scatter correction method and noise reduction scheme have been developed. The authors have performed both simulation and experimental studies to validate the rebinned BPF algorithm for image reconstruction from partially blocked cone-beam data. Quantitative evaluations of the reconstructed image quality were performed in the experimental studies. The simulation study revealed that the developed reconstruction algorithm successfully reconstructs the images from the partial cone-beam data. In the experimental study, the proposed method effectively corrected for the scatter in each projection and reconstructed scatter-corrected images from a single scan. Reduction of cupping artifacts and an enhancement of the image contrast have been demonstrated. The image contrast has increased by a factor of about 2, and the image accuracy in terms of root-mean-square-error with respect to the fan-beam CT image has increased by more than 30%. The authors have successfully demonstrated that the proposed scanning method and image
Model Based Control of Single-Phase Marine Cooling Systems
DEFF Research Database (Denmark)
Hansen, Michael
2014-01-01
these systems. Traditionally, control for this type of cooling system has been limited to open-loop control of pumps combined with a couple of local PID controllers for bypass valves to keep critical temperatures within design limits. This research considers improvements in a retrofit framework to the control...... linearization, an H∞-control design is applied to the resulting linear system. Disturbance rejection capabilities and robustness of performance for this control design methodology is compared to a baseline design derived from classical control theory. This shows promising results for the nonlinear robust design......This thesis is concerned with the problem of designing model-based control for a class of single-phase marine cooling systems. While this type of cooling system has been in existence for several decades, it is only recently that energy efficiency has become a focus point in the design and operation...
Modeling of a single-phase photovoltaic inverter
Energy Technology Data Exchange (ETDEWEB)
Maris, T.I. [Department of Electrical Engineering, Technological Educational Institute of Chalkida, 334 40 Psachna Evias (Greece); Kourtesi, St. [Hellenic Public Power Corporation S.A., 22 Chalcocondyli Str., 104 32 Athens (Greece); Ekonomou, L. [Hellenic American University, 12 Kaplanon Str., 106 80 Athens (Greece); Fotis, G.P. [National Technical University of Athens, School of Electrical and Computer Engineering, High Voltage Laboratory, 9 Iroon Politechniou St., Zografou, 157 80 Athens (Greece)
2007-11-06
The paper presents the design of a single-phase photovoltaic inverter model and the simulation of its performance. Furthermore, the concept of moving real and reactive power after coupling this inverter model with an a.c. source representing the main power distribution grid was studied. Brief technical information is given on the inverter design, with emphasis on the operation of the circuit used. In the technical information section, a description of real and reactive power components is given with special reference to the control of these power components by controlling the power angle or the difference in voltage magnitudes between two voltage sources. This a.c. converted voltage has practical interest, since it is useful for feeding small house appliances. (author)
Benchmarks for single-phase flow in fractured porous media
Flemisch, Bernd; Berre, Inga; Boon, Wietse; Fumagalli, Alessio; Schwenck, Nicolas; Scotti, Anna; Stefansson, Ivar; Tatomir, Alexandru
2018-01-01
This paper presents several test cases intended to be benchmarks for numerical schemes for single-phase fluid flow in fractured porous media. A number of solution strategies are compared, including a vertex and two cell-centred finite volume methods, a non-conforming embedded discrete fracture model, a primal and a dual extended finite element formulation, and a mortar discrete fracture model. The proposed benchmarks test the schemes by increasing the difficulties in terms of network geometry, e.g. intersecting fractures, and physical parameters, e.g. low and high fracture-matrix permeability ratio as well as heterogeneous fracture permeabilities. For each problem, the results presented are the number of unknowns, the approximation errors in the porous matrix and in the fractures with respect to a reference solution, and the sparsity and condition number of the discretized linear system. All data and meshes used in this study are publicly available for further comparisons.
Vavrin, R; Kohlbrecher, J; Wilk, A; Ratajczyk, M; Lettinga, M P; Buitenhuis, J; Meier, G
2009-04-21
We have applied small angle neutron scattering (SANS), diffusing wave spectroscopy (DWS), and dynamic light scattering (DLS) to investigate the phase diagram of a sterically stabilized colloidal system consisting of octadecyl grafted silica particles dispersed in toluene. This system is known to exhibit gas-liquid phase separation and percolation, depending on temperature T, pressure P, and concentration phi. We have determined by DLS the pressure dependence of the coexistence temperature and the spinodal temperature to be dP/dT=77 bar/K. The gel line or percolation limit was measured by DWS under high pressure using the condition that the system became nonergodic when crossing it and we determined the coexistence line at higher volume fractions from the DWS limit of turbid samples. From SANS measurements we determined the stickiness parameter tau(B)(P,T,phi) of the Baxter model, characterizing a polydisperse adhesive hard sphere, using a global fit routine on all curves in the homogenous regime at various temperatures, pressures, and concentrations. The phase coexistence and percolation line as predicted from tau(B)(P,T,phi) correspond with the determinations by DWS and were used to construct an experimental phase diagram for a polydisperse sticky hard sphere model system. A comparison with theory shows good agreement especially concerning the predictions for the percolation threshold. From the analysis of the forward scattering we find a critical scaling law for the susceptibility corresponding to mean field behavior. This finding is also supported by the critical scaling properties of the collective diffusion.
Mechanism of Pseudogap Detected by Electronic Raman Scattering: Phase Fluctuation or Hidden Order?
International Nuclear Information System (INIS)
Hong-Yan, Lu; Yuan, Wan; Xiang-Mei, He; Qiang-Hua, Wang
2009-01-01
We study the electronic Raman scattering in the cuprates to distinguish the two possible scenarios of the pseudo-gap normal state. In one scenario, the pseudogap is assumed to be caused by phase fluctuations of the preformed Cooper pairs. We find that pair-breaking peaks appear in both the B 1g and B 2g Raman channels, and they are smeared and tend to shift to the same energy with the increasing strength of phase fluctuations. Thus both channels reflect the same pairing energy scale, irrespectively of the doping level. In another scenario, the pseudogap is assumed to be caused by a hidden order that competes with the superconducting order. As an example, we assume that the hidden order is the d-density-wave (DDW) order. We find analytically and numerically that in the DDW normal state there is no Raman peak in the B 2g channel in a tight-binding model up to the second nearest-neighbor hopping, while the Raman peak in the B 1g channel reflects the energy gap caused by the DDW order. This behavior is in agreement with experiments in the pseudogap normal state. To gain further insights, we also calculate the Raman spectra in the DDW+SC state. We study the doping and temperature dependence of the peak energy in both channels and find a two-gap behavior, which is in agreement with recent Raman experiments. Therefore, our results shed light on the hidden order scenario for the pseudogap
Resonant magneto-optic Kerr effects of a single Ni nanorod in the Mie scattering regime.
Jeong, Ho-Jin; Kim, Dongha; Song, Jung-Hwan; Jeong, Kwang-Yong; Seo, Min-Kyo
2016-07-25
We present a systematic, theoretical investigation of the polar magneto-optical (MO) Kerr effects of a single Ni nanorod in the Mie regime. The MO Kerr rotation, ellipticity, amplitude ratio, and phase shift are calculated as a function of the length and width of the nanorod. The electric field amplitude ratio of the MO Kerr effect is locally maximized when the nanorod supports a plasmonic resonance in the polarization state orthogonal to the incident light. The plasmonic resonances directly induced by the incident light do not enhance the amplitude ratio. In the Mie regime, multiple local maxima of the MO Kerr activity are supported by the resonant modes with different modal characteristics. From the viewpoint of first-order perturbation analysis, the spatial overlap between the incident-light-induced electric field and the Green function determines the local maxima.
Measurement of fluorophore concentration in scattering media by a single optical fiber
Stepp, Herbert; Beck, Tobias; Beyer, Wolfgang; Pfaller, Christian; Sroka, Ronald; Baumgartner, Reinhold
2006-02-01
Motivation: Photodynamic Therapy (PDT) with interstitial light delivery by multiple fibers for the treatment of large tissue volumes requires measurement of sensitizer distribution for dosimetric considerations. For stereotactic interstitial PDT of malignant glioma, for instance, a pre-irradiation comparison of the contrast enhancing tissue volume in MR-imaging with the photosensitized volume as assessed by fluorescence detection is desirable. For PDT of prostate cancer, the quantitative measurement of the selectivity of sensitizer uptake in cancer versus normal prostate parenchyma is important. Methods: It has previously been shown by others that the fluorescence intensity measured by a thin single optical fiber for excitation and detection is largely independent on optical parameters of the tissue that contains the fluorochrome. However, the investigators assumed similar values for excitation and emission wavelengths. This study concerned liquid phantom measurements (absorber: ink or hemoglobin, fluorochrome: Na-fluorescein) and Monte Carlo calculations, with extended conditions, where the absorption differs by a factor of 10 between excitation (426 nm) and emission (530 nm) wavelengths. The absorption coefficient (μ a') was varied between 0.01 - 0.3 mm-1 (@ 426 nm), the effective scattering coefficient (μ s') between 0.6 - 2.5 mm-1. A 200 μm and a 1000 μm core fiber were used. Results: Fluorescence intensity measured at 530 nm via a thin optical fiber (core diameter small compared to light penetration depth) depends minimally on optical tissue parameters. This result is valid for ink as absorber (μa identical at excitation and emission) as well as for hemoglobin (μa different). Fluorochrome concentration measurements seem possible with a 200 μm core fiber, but not with the 1000 μm core fiber.
Directory of Open Access Journals (Sweden)
S. Kazadzis
2010-08-01
Full Text Available The possibility of measuring aerosol optical absorption properties in the UV spectral range such as single scattering albedo (SSA, using remote sensing techniques, is currently an open scientific issue. We investigate the limitations on calculating column average SSA using a combination of global UV spectral measurements (that are comon in various UV monitoring stations worldwide with radiative transfer modeling. To point out the difficulties in such a retrieval we have used the travelling reference spectroradiometer QASUME (Quality Assurance of Spectral Ultraviolet Measurements in Europe results from 27 visits to UV monitoring stations around Europe. We have used the QASUME instrument as relative reference, analyzing absolute differences and also temporal and spectral deviations of UV irraidances, that are used as basic input for the SSA retrieval.
The results comparing the mean SSA derived by all instruments, measuring synchronous UV spectra, showed that 5 were within ± 0.02 difference from the SSA calculated from the QASUME instrument, while 17 were within ± 0.04, for the Solar zenith angle of 60 degrees. As for the uncertainty that has been calculated using the 2σ standard deviation of the spectral measurements, a mean 0.072 and 0.10 (2σ uncertainties have been calculated for 60° and 30°, respectively. Based on the fact that additional uncertainties would be introduced in the SSA retrieval from AOD model input accuracy, assymetry parameter assumptions, we show that only very few instrumnents could be able to detect long term SSA changes. However, such measurements/results ar useful in order to retrieve SSA at UV wavelengths, a product needed for various applications such as, inputs for modeling radiative forcing studies and satellite retrieval algorithms.
Wibking, Benjamin D.; Thompson, Todd A.; Krumholz, Mark R.
2018-04-01
The radiation force on dust grains may be dynamically important in driving turbulence and outflows in rapidly star-forming galaxies. Recent studies focus on the highly optically-thick limit relevant to the densest ultra-luminous galaxies and super star clusters, where reprocessed infrared photons provide the dominant source of electromagnetic momentum. However, even among starburst galaxies, the great majority instead lie in the so-called "single-scattering" limit, where the system is optically-thick to the incident starlight, but optically-thin to the re-radiated infrared. In this paper we present a stability analysis and multidimensional radiation-hydrodynamic simulations exploring the stability and dynamics of isothermal dusty gas columns in this regime. We describe our algorithm for full angle-dependent radiation transport based on the discontinuous Galerkin finite element method. For a range of near-Eddington fluxes, we show that the medium is unstable, producing convective-like motions in a turbulent atmosphere with a scale height significantly inflated compared to the gas pressure scale height and mass-weighted turbulent energy densities of ˜0.01 - 0.1 of the midplane radiation energy density, corresponding to mass-weighted velocity dispersions of Mach number ˜0.5 - 2. Extrapolation of our results to optical depths of 103 implies maximum turbulent Mach numbers of ˜20. Comparing our results to galaxy-averaged observations, and subject to the approximations of our calculations, we find that radiation pressure does not contribute significantly to the effective supersonic pressure support in star-forming disks, which in general are substantially sub-Eddington. We further examine the time-averaged vertical density profiles in dynamical equilibrium and comment on implications for radiation-pressure-driven galactic winds.
Realization of single-phase single-stage grid-connected PV system
Directory of Open Access Journals (Sweden)
Osama M. Arafa
2017-05-01
Full Text Available This paper presents a single phase single stage grid-tied PV system. Grid angle detection is introduced to allow operation at any arbitrary power factor but unity power factor is chosen to utilize the full inverter capacity. The system ensures MPPT using the incremental conductance method and it can track the changes in insolation level without oscillations. A PI voltage controller and a dead-beat current controller are used to ensure high quality injected current to the grid. The paper investigates the system structure and performance through numerical simulation using Matlab/Simulink. An experimental setup controlled by the MicrolabBox DSP prototyping platform is utilized to realize the system and study its performance. The precautions for smooth and safe system operation including the startup sequence are fully considered in the implementation.
A grid-connected single-phase photovoltaic micro inverter
Wen, X. Y.; Lin, P. J.; Chen, Z. C.; Wu, L. J.; Cheng, S. Y.
2017-11-01
In this paper, the topology of a single-phase grid-connected photovoltaic (PV) micro-inverter is proposed. The PV micro-inverter consists of DC-DC stage with high voltage gain boost and DC-AC conversion stage. In the first stage, we apply the active clamp circuit and two voltage multipliers to achieve soft switching technology and high voltage gain. In addition, the flower pollination algorithm (FPA) is employed for the maximum power point tracking (MPPT) in the PV module in this stage. The second stage cascades a H-bridge inverter and LCL filter. To feed high quality sinusoidal power into the grid, the software phase lock, outer voltage loop and inner current loop control method are adopted as the control strategy. The performance of the proposed topology is tested by Matlab/Simulink. A PV module with maximum power 300W and maximum power point voltage 40V is applied as the input source. The simulation results indicate that the proposed topology and the control strategy are feasible.
Kaina, Nadège; Lemoult, Fabrice; Fink, Mathias; Lerosey, Geoffroy
2015-09-03
Metamaterials, man-made composite media structured on a scale much smaller than a wavelength, offer surprising possibilities for engineering the propagation of waves. One of the most interesting of these is the ability to achieve superlensing--that is, to focus or image beyond the diffraction limit. This originates from the left-handed behavior--the property of refracting waves negatively--that is typical of negative index metamaterials. Yet reaching this goal requires the design of 'double negative' metamaterials, which act simultaneously on the permittivity and permeability in electromagnetics, or on the density and compressibility in acoustics; this generally implies the use of two different kinds of building blocks or specific particles presenting multiple overlapping resonances. Such a requirement limits the applicability of double negative metamaterials, and has, for example, hampered any demonstration of subwavelength focusing using left-handed acoustic metamaterials. Here we show that these strict conditions can be largely relaxed by relying on media that consist of only one type of single resonant unit cell. Specifically, we show with a simple yet general semi-analytical model that judiciously breaking the symmetry of a single negative metamaterial is sufficient to turn it into a double negative one. We then demonstrate that this occurs solely because of multiple scattering of waves off the metamaterial resonant elements, a phenomenon often disregarded in these media owing to their subwavelength patterning. We apply our approach to acoustics and verify through numerical simulations that it allows the realization of negative index acoustic metamaterials based on Helmholtz resonators only. Finally, we demonstrate the operation of a negative index acoustic superlens, achieving subwavelength focusing and imaging with spot width and resolution 7 and 3.5 times better than the diffraction limit, respectively. Our findings have profound implications for the
DEFF Research Database (Denmark)
Lorenzen, Michael Rodas; Noordegraaf, Danny; Nielsen, Carsten Vandel
2009-01-01
An increased gain in a fibre-optical parametric amplifier through suppression of stimulated Brillouin scattering is demonstrated by applying a temperature distribution along the fibre for a fixed phase modulation of the pump. The temperature distribution slightly impacts the gain spectrum....
Salamat, G.; Vries, de R.; Kaler, E.W.; Satija, S.; Sung, L.
2000-01-01
Neutron reflectivity of lamellar phases containing pentaethylene glycol n-dodecyl ether, sodium decylsulfonate, and D2O is measured at the solid-liquid interface. The scattering length density profiles deduced from fits to the reflectivity data show that undulations of the mixed surfactant bilayers
Czech Academy of Sciences Publication Activity Database
Yaicle, C.; Martin, C.; Jirák, Zdeněk; Fauth, F.; André, G.; Suard, E.; Maignan, A.; Hardy, V.; Retoux, R.; Hervieu, M.
2003-01-01
Roč. 68, č. 22 (2003), s. 224412-1 - 224412-8 ISSN 0163-1829 Institutional research plan: CEZ:AV0Z1010914 Keywords : phase-separated manganite * magnetic and structural transitions * neutron scattering Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.962, year: 2003
Abbiendi, G; Akesson, P.F.; Alexander, G.; Allison, John; Amaral, P.; Anagnostou, G.; Anderson, K.J.; Arcelli, S.; Asai, S.; Axen, D.; Azuelos, G.; Bailey, I.; Barberio, E.; Barlow, R.J.; Batley, R.J.; Bechtle, P.; Behnke, T.; Bell, Kenneth Watson; Bell, P.J.; Bella, G.; Bellerive, A.; Benelli, G.; Bethke, S.; Biebel, O.; Boeriu, O.; Bock, P.; Boutemeur, M.; Braibant, S.; Brigliadori, L.; Brown, Robert M.; Buesser, K.; Burckhart, H.J.; Campana, S.; Carnegie, R.K.; Caron, B.; Carter, A.A.; Carter, J.R.; Chang, C.Y.; Charlton, David G.; Csilling, A.; Cuffiani, M.; Dado, S.; De Roeck, A.; De Wolf, E.A.; Desch, K.; Dienes, B.; Donkers, M.; Dubbert, J.; Duchovni, E.; Duckeck, G.; Duerdoth, I.P.; Etzion, E.; Fabbri, F.; Feld, L.; Ferrari, P.; Fiedler, F.; Fleck, I.; Ford, M.; Frey, A.; Furtjes, A.; Gagnon, P.; Gary, John William; Gaycken, G.; Geich-Gimbel, C.; Giacomelli, G.; Giacomelli, P.; Giunta, Marina; Goldberg, J.; Groll, M.; Gross, E.; Grunhaus, J.; Gruwe, M.; Gunther, P.O.; Gupta, A.; Hajdu, C.; Hamann, M.; Hanson, G.G.; Harder, K.; Harel, A.; Harin-Dirac, M.; Hauschild, M.; Hawkes, C.M.; Hawkings, R.; Hemingway, R.J.; Hensel, C.; Herten, G.; Heuer, R.D.; Hill, J.C.; Hoffman, Kara Dion; Horvath, D.; Igo-Kemenes, P.; Ishii, K.; Jeremie, H.; Jovanovic, P.; Junk, T.R.; Kanaya, N.; Kanzaki, J.; Karapetian, G.; Karlen, D.; Kawagoe, K.; Kawamoto, T.; Keeler, R.K.; Kellogg, R.G.; Kennedy, B.W.; Kim, D.H.; Klein, K.; Klier, A.; Kluth, S.; Kobayashi, T.; Kobel, M.; Komamiya, S.; Kormos, Laura L.; Kramer, T.; Krieger, P.; von Krogh, J.; Kruger, K.; Kuhl, T.; Kupper, M.; Lafferty, G.D.; Landsman, H.; Lanske, D.; Layter, J.G.; Leins, A.; Lellouch, D.; Lettso, J.; Levinson, L.; Lillich, J.; Lloyd, S.L.; Loebinger, F.K.; Lu, J.; Ludwig, J.; Macpherson, A.; Mader, W.; Marcellini, S.; Martin, A.J.; Masetti, G.; Mashimo, T.; Mattig, Peter; McDonald, W.J.; McKenna, J.; McMahon, T.J.; McPherson, R.A.; Meijers, F.; Menges, W.; Merritt, F.S.; Mes, H.; Michelini, A.; Mihara, S.; Mikenberg, G.; Miller, D.J.; Moed, S.; Mohr, W.; Mori, T.; Mutter, A.; Nagai, K.; Nakamura, I.; Nanjo, H.; Neal, H.A.; Nisius, R.; O'Neale, S.W.; Oh, A.; Okpara, A.; Oreglia, M.J.; Orito, S.; Pahl, C.; Pasztor, G.; Pater, J.R.; Patrick, G.N.; Pilcher, J.E.; Pinfold, J.; Plane, David E.; Poli, B.; Polok, J.; Pooth, O.; Przybycien, M.; Quadt, A.; Rabbertz, K.; Rembser, C.; Renkel, P.; Roney, J.M.; Rosati, S.; Rozen, Y.; Runge, K.; Sachs, K.; Saeki, T.; Sarkisyan, E.K.G.; Schaile, A.D.; Schaile, O.; Scharff-Hansen, P.; Schieck, J.; Schoerner-Sadenius, Thomas; Schroder, Matthias; Schumacher, M.; Schwick, C.; Scott, W.G.; Seuster, R.; Shears, T.G.; Shen, B.C.; Sherwood, P.; Siroli, G.; Skuja, A.; Smith, A.M.; Sobie, R.; Soldner-Rembold, S.; Spano, F.; Stahl, A.; Stephens, K.; Strom, David M.; Strohmer, R.; Tarem, S.; Tasevsky, M.; Taylor, R.J.; Teuscher, R.; Thomson, M.A.; Torrence, E.; Toya, D.; Tran, P.; Trigger, I.; Trocsanyi, Z.; Tsur, E.; Turner-Watson, M.F.; Ueda, I.; Ujvari, B.; Vollmer, C.F.; Vannerem, P.; Vertesi, R.; Verzocchi, M.; Voss, H.; Vossebeld, J.; Waller, D.; Ward, C.P.; Ward, D.R.; Watkins, P.M.; Watson, A.T.; Watson, N.K.; Wells, P.S.; Wengler, T.; Wermes, N.; Wetterling, G.W.; Wilson, D.; Wilson, J.A.; Wolf, G.; Wyatt, T.R.; Yamashita, S.; Zer-Zion, D.; Zivkovic, Lidija
2003-01-01
A search for single production of doubly-charged Higgs bosons has been performed using 600.7 pb^-1 of e+e- collision data with sqrt(s)=189--209GeV collected by the OPAL detector at LEP. No evidence for the existence of H++/-- is observed. Upper limits on the Yukawa coupling of the H++/-- to like-signed electron pairs are derived. Additionally, indirect constraints on the Yukawa coupling from Bhabha scattering, where the H++/-- would contribute via t-channel exchange, are derived for M(H++/--) < 2TeV. These are the first results for both a single production search and constraints from Bhabha scattering reported from LEP.
Okamoto, Toshihiro; Fukuta, Tetsuya; Sato, Shuji; Haraguchi, Masanobu; Fukui, Masuo
2011-04-11
We succeeded in making a silver split-ring (SR) structure of approximately 130 nm in diameter on a glass substrate using a nanosphere lithography technique. The light scattering spectrum in visible near-infrared region of a single, isolated SR was measured using a microscope spectroscopy optical system. The electromagnetic field enhancement spectrum and distribution of the SR structure were simulated by the finite-difference time-domain method, and the excitation modes were clarified. The long wavelength peak in the light scattering spectra corresponded to a fundamental LC resonance mode excited by an incident electric field. It was shown that a single SR structure fabricated as abovementioned can operate as a resonator and generate a magnetic dipole. © 2011 Optical Society of America
DEFF Research Database (Denmark)
Lico, Pasqualino; Marinelli, Mattia; Knezovic, Katarina
2015-01-01
In Denmark, household consumers are supplied with three phase with neutral cable. In addition, the distribution service operator cannot decide to which phase electrical appliance are connected. The technician who realizes the installation connects the loads according to his technical expertise...... stations are equipped with single-phase converters. According to the designed control strategy, the charging spot can select the phase to be used for the charge. The selection is done according to a phase voltage measurement....
Domínguez-Serna, Francisco A.; Mendieta-Jimenez, Francisco J.; Rojas, Fernando
2017-10-01
We study quantum correlations and discord in a bipartite continuous variable hybrid system formed by linear combinations of coherent states {|{α }\\rangle } and single photon-added coherent states of the form {|{ψ }\\rangle }_{ {dp(pa)}}= N/√{2} (\\hat{a}^\\dagger {|{α }\\rangle }_a{|{α }\\rangle }_b ± \\hat{b}^\\dagger {|{α }\\rangle }_a{|{α }\\rangle }_b). We stablish a relationship between the quantum discord with a local observable (the quadrature variance for one subsystem) under the influence of scattering and phase fluctuation noise. For the pure states the quantum correlations are characterized by means of measurement induced disturbance (MID) with simultaneous quadrature measurements. In a scenario where homodyne conditional measurements are available we show that the MID provides an easy way to select optimal phases to obtain information of the maximal correlations in the channels. The quantum correlations of these entangled states with channel losses are quantitatively characterized with the quantum discord (QD) with a displaced qubit projector. We observe that as scattering increases, QD decreases monotonically. At the same time for the state {|{ψ }\\rangle }_{ {dp}}, QD is more resistant to high phase fluctuations when the average photon number n_0 is bigger than zero, but if phase fluctuations are low, QD is more resistant if n_0=0. For the dp model with scattering, we obtain an analytical expression of the QD as a function of the observable quadrature variance in a local subsystem. This relation allows us to have a way to obtain the degree of QD in the channel by just measuring a local property observable such as the quadrature variance. For the other model this relation still exists but is explored numerically. This relation is an important result that allows to identify quantum processing capabilities in terms of just local observables.
SAD phasing with in-house cu Ka radiation using barium as anomalous scatterer.
Dhanasekaran, V; Velmurugan, D
2011-12-01
Phasing of lysozyme crystals using co-crystallized barium ions was performed using single-wavelength anomalous diffraction (SAD) method using Cu Ka radiation with in-house source of data collection. As the ion binding sites vary with respect to the pH of the buffer during crystallization, the highly isomorphic forms of lysozyme crystals grown at acidic and alkaline pH were used for the study. Intrinsic sulphur anomalous signal was also utilized with anomalous signal from lower occupancy ions for phasing. The study showed that to solve the structure by SAD technique, 2.8-fold data redundancy was sufficient when barium was used as an anomalous marker in the in-house copper X-ray radiation source for data collection. Therefore, co-crystallization of proteins with barium containing salt can be a powerful tool for structure determination using lab source.
International Nuclear Information System (INIS)
Hategan, Cornel; Comisel, Horia; Ionescu, Remus A.
2004-01-01
The quasiresonant scattering consists from a single channel resonance coupled by direct interaction transitions to some competing reaction channels. A description of quasiresonant Scattering, in terms of generalized reduced K-, R- and S- Matrix, is developed in this work. The quasiresonance's decay width is, due to channels coupling, smaller than the width of the ancestral single channel resonance (resonance's direct compression). (author)
Trajectory approach to dissipative quantum phase space dynamics: Application to barrier scattering
International Nuclear Information System (INIS)
Hughes, Keith H.; Wyatt, Robert E.
2004-01-01
The Caldeira-Leggett master equation, expressed in Lindblad form, has been used in the numerical study of the effect of a thermal environment on the dynamics of the scattering of a wave packet from a repulsive Eckart barrier. The dynamics are studied in terms of phase space trajectories associated with the distribution function, W(q,p,t). The equations of motion for the trajectories include quantum terms that introduce nonlocality into the motion, which imply that an ensemble of correlated trajectories needs to be propagated. However, use of the derivative propagation method (DPM) allows each trajectory to be propagated individually. This is achieved by deriving equations of motion for the partial derivatives of W(q,p,t) that appear in the master equation. The effects of dissipation on the trajectories are studied and results are shown for the transmission probability. On short time scales, decoherence is demonstrated by a swelling of trajectories into momentum space. For a nondissipative system, a comparison is made of the DPM with the 'exact' transmission probability calculated from a fixed grid calculation
Servo characteristics of single-phase spindle motor in DVD-ROM
Wang, KingYin; Kuei, ChingPing; Chang, SungSan; Lee, YaoYu; Kuo, YuHung
2000-07-01
The single-phase DC motor has the low-cost advantage over 3- phase DC motor owing to its easy-assembling and high yield- rate, however, it has larger torque ripple and cogging torque. Single-phase DC motor is currently applied to low profit margin products such as cooling fan. In order to utilize single-phase DC motor to high precision system, for instance, DVD (Digital Versatile Disk), the vibration caused by torque ripple and cogging torque needs to be solved. In this paper, focusing error, tracking error, seeking ability and some velocity control performances are studied when single-phase DC motor is used in DVD related products.
International Nuclear Information System (INIS)
Graczykowski, B; Mielcarek, S; Mroz, B; Breczewski, T; No, M L; San-Juan, J
2013-01-01
The paper presents the influence of the martensitic phase transition on hypersonic thermally excited surface acoustic waves propagating in Cu–14%Al–4%Ni (wt%) shape memory alloy. Non-destructive and non-contact testing using Brillouin light scattering spectroscopy permitted determination of the elastic constants of austenite versus temperature. Experimental results obtained for martensite were interpreted using the proposed model of the cubic to orthorhombic martensitic phase transition based on the Landau model of a first-order phase transition. Additionally we adopted the approximation of the domain structure of martensite by a polycrystalline sample using the Voigt–Reuss–Hill procedure of averaging the elastic constants. (paper)
Valdés, Felipe
2011-06-01
A new regularized single source equation for analyzing scattering from homogeneous penetrable objects is presented. The proposed equation is a linear combination of a Calderón-preconditioned single source electric field integral equation and a single source magnetic field integral equation. The equation is immune to low-frequency and dense-mesh breakdown, and free from spurious resonances. Unlike dual source formulations, this equation involves operator products that cannot be discretized using standard procedures for discretizing standalone electric, magnetic, and combined field operators. Instead, the single source equation proposed here is discretized using a recently developed technique that achieves a well-conditioned mapping from div- to curl-conforming function spaces, thereby fully respecting the space mapping properties of the operators involved, and guaranteeing accuracy and stability. Numerical results show that the proposed equation and discretization technique give rise to rapidly convergent solutions. They also validate the equation\\'s resonant free character. © 2006 IEEE.
International Nuclear Information System (INIS)
Matveev, V.M.; Matveev, V.V.
1999-01-01
Complete text of publication follows. Complete text of publication follows. New polarization-sensitive methods for reconstruction of magnetization and electron density profiles in rare earth materials and structures based on polarization neutron and X-ray Kerr-effect measurements used singly or in combination are examined. Kerr-effect measurements under resonant spectral condition near the M-absorption edges of rare earth elements are shown to provide complementary information which allows one to retrieve the phase of the neutron scattering amplitude and to reconstruct the unknown profile of interest in a non-destructive manner without any reference layers. Strengths and weaknesses of the retrieving-phase methods based on polarization neutron and X-ray measurements in different magnetic-reference-layers scheme are considered as well. (author)
Directory of Open Access Journals (Sweden)
M. Collaud Coen
2004-01-01
Full Text Available Scattering and absorption coefficients have been measured continuously at several wavelengths since March 2001 at the high altitude site Jungfraujoch (3580ma.s.l.. From these data, the wavelength dependences of the Ångström exponent and particularly of the single scattering albedo are determined. While the exponent of the single scattering albedo usually increases with wavelength, it decreases with wavelength during Saharan dust events (SDE due to the greater size of the mineral aerosol particles and their different chemical composition. This change in the sign of the single scattering exponent turns out to be a sensitive means for detecting Saharan dust events. The occurrence of SDE detected by this new method was confirmed by visual inspection of filter colors and by studying long-range back-trajectories. An examination of SDE over a 22-month period shows that SDE are more frequent during the March-June period as well as during October and November. The trajectory analysis indicated a mean traveling time of 96.5h, with the most important source countries situated in the northern and north-western part of the Saharan desert. Most of the SDE do not lead to a detectable increase of the 48-h total suspended particulate matter (TSP concentration at the Jungfraujoch. During Saharan dust events, the average contribution of this dust to hourly TSP at the Jungfraujoch is 16µg/m3, which corresponds to an annual mean of 0.8µg/m3 or 24% of TSP.
Menxi Xie; CanYan Zhu; BingWei Shi; Yong Yang
2017-01-01
High performance synchronization methord is citical for grid connected power converter. For single-phase system, power based phase-locked loop(pPLL) uses a multiplier as phase detector(PD). As single-phase grid voltage is distorted, the phase error information contains ac disturbances oscillating at integer multiples of fundamental frequency which lead to detection error. This paper presents a new scheme based on moving average filter(MAF) applied in-loop of pPLL. The signal characteristic of...
Performance Improvement of Single Phase Inverter using SPWM
Gavaskar Reddy, B., Dr; Maheswari, L., Dr; Ganeswari Kale, Adi
2017-08-01
This paper concentrates on modelling and simulation of single phase inverter as a frequency changer modulated by Pulse Width Modulation (PWM). An inverter is a circuit that converts DC sources to AC sources. Pulse Width Modulation is a method that utilization as an approach to abatement add up to harmonic distortion in inverter circuit. The model is executed utilizing MATLAB/Simulink software with the SimPower System Block Set in light of PC simulation. PC simulation assumes an imperative part in the plan, investigation, and assessment of force electronic converter and their controller. MATLAB is a successful instrument to examine a PWM inverter. Preferences of utilizing MATLAB are the accompanying: Faster reaction, accessibility of different simulation devices and utilitarian squares and the nonappearance of joining issues. Safe-replacement methodology need be actualized is to explain exchanging Transients. In this way, Insulated Gate Bipolar Transistor (IGBT) is use as exchanging gadgets. IGBT is ideal since it is anything but difficult to control and low misfortunes. The outcome from Simulink was checked utilizing MATLAB simulation.
Self-assembled single-phase perovskite nanocomposite thin films.
Kim, Hyun-Suk; Bi, Lei; Paik, Hanjong; Yang, Dae-Jin; Park, Yun Chang; Dionne, Gerald F; Ross, Caroline A
2010-02-10
Thin films of perovskite-structured oxides with general formula ABO(3) have great potential in electronic devices because of their unique properties, which include the high dielectric constant of titanates, (1) high-T(C) superconductivity in cuprates, (2) and colossal magnetoresistance in manganites. (3) These properties are intimately dependent on, and can therefore be tailored by, the microstructure, orientation, and strain state of the film. Here, we demonstrate the growth of cubic Sr(Ti,Fe)O(3) (STF) films with an unusual self-assembled nanocomposite microstructure consisting of (100) and (110)-oriented crystals, both of which grow epitaxially with respect to the Si substrate and which are therefore homoepitaxial with each other. These structures differ from previously reported self-assembled oxide nanocomposites, which consist either of two different materials (4-7) or of single-phase distorted-cubic materials that exhibit two or more variants. (8-12) Moreover, an epitaxial nanocomposite SrTiO(3) overlayer can be grown on the STF, extending the range of compositions over which this microstructure can be formed. This offers the potential for the implementation of self-organized optical/ferromagnetic or ferromagnetic/ferroelectric hybrid nanostructures integrated on technologically important Si substrates with applications in magnetooptical or spintronic devices.
Single particle detection: Phase control in submicron Hall sensors
International Nuclear Information System (INIS)
Di Michele, Lorenzo; Shelly, Connor; Gallop, John; Kazakova, Olga
2010-01-01
We present a phase-sensitive ac-dc Hall magnetometry method which allows a clear and reliable separation of real and parasitic magnetic signals of a very small magnitude. High-sensitivity semiconductor-based Hall crosses are generally accepted as a preferential solution for non-invasive detection of superparamagnetic nanobeads used in molecular biology, nanomedicine, and nanochemistry. However, detection of such small beads is often hindered by inductive pick-up and other spurious signals. The present work demonstrates an unambiguous experimental route for detection of small magnetic moments and provides a simple theoretical background for it. The reliability of the method has been tested for a variety of InSb Hall sensors in the range 600 nm-5 μm. Complete characterization of empty devices, involving Hall coefficients and noise measurements, has been performed and detection of a single FePt bead with diameter of 140 nm and magnetic moment of μ≅10 8 μ B has been achieved with a 600 nm-wide sensor.
Energy Technology Data Exchange (ETDEWEB)
Bordenave-Montesquieu, D.; Dagnac, R. (Toulouse-3 Univ., 31 (France). Centre de Physique Atomique)
1992-06-14
We studied the single-electron capture as well as the direct processes occurring when a He[sup 2+] ion is scattered by a He target. Doubly differential cross sections were measured for single-electron capture with a collision energy ranging from 2 to 8 keV and a scattering angle varying from 10' to 3[sup o]30' (laboratory frame). Single-electron capture into excited states of He[sup +] was found to be the dominant process, confirming a previous experimental study. Elastic scattering and ionization differential cross sections were measured for E = 6 keV. (Author).
Novel Instrument to Measure Aerosol Fluorescence, Absorption, and Scattering, Phase I
National Aeronautics and Space Administration — Picarro, Inc proposes to develop the first cavity ringdown spectroscopy (CRDS) system to measure fluorescence, absorption, and scattering properties of atmospheric...
Δ33 resonance in pion nucleus elastic, single, and double charge exchange scattering
International Nuclear Information System (INIS)
Johnson, M.B.
1983-01-01
The Δ 33 resonance is strongly excited in pion-nucleon scattering, but there is clearly only a limited amount of information that can be learned in scattering the pion from an isolated nucleon. One learns that there is a resonance of mass 1232 MeV, width 115 MeV, and, if one is willing to introduce a dynamical model, something about the off-shell extension of the amplitude. One stands to learn much more from pion-nucleus scattering because in this case the Δ 33 resonance has an opportunity to scatter from nucleons, and how this occurs is not well understood. What do we know about the Δ-N interaction for pion-nucleus scattering. The isobar-hole model was invented to deal directly with the Δ 33 -nucleus dynamics, and a phenomenological determination of the isobar shell-model potential was attempted. The unknown dynamics deltaU/sub Δ/ is contained in a central isoscalar spreading potential of strength W 0 and a spin orbit potential deltaU 0 = W 0 rho + spin-orbit. The real part of W 0 rho is measured relative to the nucleon-nucleus potential. From a more theoretical point of view, one would like to be able to calculate deltaU/sub Δ/, including its isospin dependence, from an underlying dynamical model which is formulated in terms of the basic effective meson-baryon couplings. Some salient properties of these couplings can be determined from models of quark-bag structure, which raises the exciting possibility of learning about these fundamental issues from pion scattering. Attempts at Los Alamos to build a theoretical framework to deal with these and other issues are described
Directory of Open Access Journals (Sweden)
V. S. Malyar
2016-01-01
Full Text Available A mathematical model is developed to study the operation of three-phase asynchronous motor with squirrel-cage rotor when the stator winding is powered from a single phase network. To create a rotating magnetic field one of the phases is fed through the capacitor. Due to the asymmetry of power feed not only transients, but the steady-state regimes are dynamic, so they are described by differential equations in any coordinate system. Their study cannot be carried out with sufficient adequacy on the basis of known equivalent circuits and require the use of dynamic parameters. In the mathematical model the state equations of the circuits of the stator and rotor are composed in the stationary three phase coordinate system. Calculation of the established mode is performed by solving the boundary problem that makes it possible to obtain the coordinate dependences over the period, without calculation of the transient process. In order to perform it, the original nonlinear differential equations are algebraized by approximating the variables with the use of cubic splines. The resulting nonlinear system of algebraic equations is a discrete analogue of the initial system of differential equations. It is solved by parameter continuation method. To calculate the static characteristics as a function of a certain variable, the system is analytically differentiated, and then numerically integrated over this variable. In the process of integration, Newton's refinement is performed at each step or at every few steps, making it possible to implement the integration in just a few steps using Euler's method. Jacobi matrices in both cases are the same. To account for the current displacement in the rods of the squirrel-cage rotor, each of them, along with the squirrel-cage rings, is divided in height into several elements. This results in several squirrel-cage rotor windings which are represented by three-phase windings with magnetic coupling between them.
The structural and compositional analysis of single crystal surfaces using low energy ion scattering
International Nuclear Information System (INIS)
Armour, D.G.; Van der Berg, J.A.; Verheij, IL.K.
1979-01-01
The use of ion scattering for surface composition and structure analysis has been reviewed. The extreme surface specificity of this technique has been widely used to obtain quitative information in a straightforward way, but the/aolc/currence of charge exchange processes, thermal lattice vibrations and multiple scattering have precluded quantitative analysis of experimental data. Examples are quoted to illustrate the progress that has been made in understanding these fundamental processes and in applying this knowledge to the development of the analytical capabilities of the technique. (author)
Analytical description of photon beam phase spaces in inverse Compton scattering sources
Directory of Open Access Journals (Sweden)
C. Curatolo
2017-08-01
Full Text Available We revisit the description of inverse Compton scattering sources and the photon beams generated therein, emphasizing the behavior of their phase space density distributions and how they depend upon those of the two colliding beams of electrons and photons. The main objective is to provide practical formulas for bandwidth, spectral density, brilliance, which are valid in general for any value of the recoil factor, i.e. both in the Thomson regime of negligible electron recoil, and in the deep Compton recoil dominated region, which is of interest for gamma-gamma colliders and Compton sources for the production of multi-GeV photon beams. We adopt a description based on the center of mass reference system of the electron-photon collision, in order to underline the role of the electron recoil and how it controls the relativistic Doppler/boost effect in various regimes. Using the center of mass reference frame greatly simplifies the treatment, allowing us to derive simple formulas expressed in terms of rms momenta of the two colliding beams (emittance, energy spread, etc. and the collimation angle in the laboratory system. Comparisons with Monte Carlo simulations of inverse Compton scattering in various scenarios are presented, showing very good agreement with the analytical formulas: in particular we find that the bandwidth dependence on the electron beam emittance, of paramount importance in Thomson regime, as it limits the amount of focusing imparted to the electron beam, becomes much less sensitive in deep Compton regime, allowing a stronger focusing of the electron beam to enhance luminosity without loss of mono-chromaticity. A similar effect occurs concerning the bandwidth dependence on the frequency spread of the incident photons: in deep recoil regime the bandwidth comes out to be much less dependent on the frequency spread. The set of formulas here derived are very helpful in designing inverse Compton sources in diverse regimes, giving a
Single-phase and two phase bubbly flow in a T connection: theoretical and experimental study
International Nuclear Information System (INIS)
Hervieu, Eric
1988-01-01
The objective of this research thesis is to highlight the driving factors of the separation of phases of a bubbly flow in a T junction, and to develop a prediction model. In a first part, the author reports the rigorous formulation of equations averaged on the T volume. He shows that it's not possible to solve globally the problem with these equations. Then, he reports a bibliographical study on the modelling of a bubbly flow, and, based upon this study, highlights intrinsic characteristics of the flow, and explains its dynamic mechanisms. He reports the development of the theoretical model, and describes the experimental installation used to validate it. In the third part, he reports the study of the liquid-gas interaction, and presents the adopted approach: study of the behaviour of an isolated bubble within a single-phase flow. Experimentation is used to check theoretical predictions. Results are used to compute phase separation. The obtained results are again compared with experimental results to validate the global relevance of the model [fr
Kompatscher, M.; Bär, M.; Hecht, J.; Muheim, C.; Kohlbrecher, J.; Kostorz, G.; Wagner, W.
2002-12-01
A furnace for small-angle neutron scattering on samples heated from room temperature to 1500°C was constructed and is now available on the SANS instrument at the spallation source SINQ of the Paul Scherrer Institut in Villigen, Switzerland. Solid solution treatments and quick temperature steps are feasible combined with a motorized positioning system to precisely adjust the sample. The furnace works under high vacuum (better than 10 -4 mbar) or under controlled atmosphere. Special measures were taken to reduce parasitic scattering from the sample environment. Remote control when installed on the instrument as well as stand-alone operation for calibration and test purposes are feasible. Results of small-angle neutron scattering experiments on a polycrystal and a single crystal of Ni-11.3 at% Ti aged in situ at 600°C for up to 100 h are presented.
Energy loss of light ions scattered off Al(110) single crystal surfaces at low energy
Hausmann, S; Hofner, C; Schlathölter, Thomas; Franke, H; Narmann, A; Heiland, W
We present energy loss data taken after grazing incidence scattering of H+, H-0, He2+, He+, and He-0 off an Al(110) surface, The data is evaluated by means of a procedure that allows to extract surface electron density parameters. The obtained density parameters will be compared to those obtained
Polarized Raman scattering study of PSN single crystals and epitaxial thin films
Czech Academy of Sciences Publication Activity Database
Pokorný, Jan; Rafalovskyi, Iegor; Gregora, Ivan; Borodavka, Fedir; Savinov, Maxim; Drahokoupil, Jan; Tyunina, Marina; Kocourek, Tomáš; Jelínek, Miroslav; Bing, Y.; Ye, Z. -G.; Hlinka, Jiří
2015-01-01
Roč. 5, č. 2 (2015), "1550013-1"-"1550013-6" ISSN 2010-135X R&D Projects: GA ČR GA15-04121S; GA ČR GA15-15123S Institutional support: RVO:68378271 Keywords : PSN * relaxors * ferroelectrics * complex perovskites * Raman scattering Subject RIV: BM - Solid Matter Physics ; Magnetism
Single Electron Transistor Platform for Microgravity Proteomics, Phase II
National Aeronautics and Space Administration — This Phase II program builds from the successful Phase I efforts to demonstrate that Quantum Logic Devices' nanoelectronic platform for biological detection could...
Small-angle neutron-scattering studies of the magnetic phase diagram of MnSi
DEFF Research Database (Denmark)
Harris, P.; Lebech, B.; Hae Seop Shim
1995-01-01
The antiferromagnetic order of MnSi has been studied as function of temperature and applied magnetic field using small-angle neutron scattering. The results were analyzed using the three-dimensional resolution function and the scattering cross-section to model the diffraction data. Physical...
Carey, Ralph; Lucchese, Robert R.; Gianturco, F. A.
2013-05-01
We present scattering calculations of electron collisions with the platinum-containing compound cis-diamminedichloroplatinum (CDDP), commonly known as cisplatin, between 0.5 eV and 6 eV, and the corresponding isolated Pt atom from 0.1 eV to 10 eV. We find evidence of resonances in e--CDDP scattering, using an ab initio description of the target. We computed scattering matrix elements from equations incorporating exchange and polarization effects through the use of the static-exchange plus density functional correlation potential. Additionally, we made use of a purely local adiabatic model potential that allows Siegert eigenstates to be calculated, thereby allowing inspection of the possible resonant scattering wave functions. The total cross section for electron scattering from (5d10) 1S Pt displays a large magnitude, monotonic decay from the initial collision energies, with no apparent resonance scattering features in any scattering symmetry. By contrast, the e--CDDP scattering cross section shows a small feature near 3.8 eV, which results from a narrow, well localized resonance of b2 symmetry. These findings are then related to the possible electron-mediated mechanism of the action of CDDP on DNA replication as suggested by recent experiments.
Airapetian, A.; Akopov, N.; Akopov, Z.; Amarian, M.; Andrus, A.; Aschenauer, E. C.; Augustyniak, W.; Avakian, R.; Avetissian, A.; Avetissian, E.; Bacchetta, A.; Bailey, P.; Balin, D.; Beckmann, M.; Belostotski, S.; Bianchi, N.; Blok, H. P.; Böttcher, H.; Borissov, A.; Borysenko, A.; Bouwhuis, M.; Brüll, A.; Bryzgalov, V.; Capitani, G. P.; Cappiluppi, M.; Chen, T.; Ciullo, G.; Contalbrigo, M.; Dalpiaz, P. F.; Leo, R. De; Demey, M.; Nardo, L. De; Sanctis, E. De; Devitsin, E.; Nezza, P. Di; Düren, M.; Ehrenfried, M.; Elalaoui-Moulay, A.; Elbakian, G.; Ellinghaus, F.; Elschenbroich, U.; Fabbri, R.; Fantoni, A.; Fechtchenko, A.; Felawka, L.; Frullani, S.; Gapienko, G.; Gapienko, V.; Garibaldi, F.; Garrow, K.; Gavrilov, G.; Gharibyan, V.; Grebeniouk, O.; Gregor, I. M.; Hadjidakis, C.; Hafidi, K.; Hartig, M.; Hasch, D.; Henoch, M.; Hesselink, W. H.; Hillenbrand, A.; Hoek, M.; Holler, Y.; Hommez, B.; Hristova, I.; Iarygin, G.; Ilyichev, A.; Ivanilov, A.; Izotov, A.; Jackson, H. E.; Jgoun, A.; Kaiser, R.; Kinney, E.; Kisselev, A.; Kobayashi, T.; Kopytin, M.; Korotkov, V.; Kozlov, V.; Krauss, B.; Krivokhijine, V. G.; Lagamba, L.; Lapikás, L.; Laziev, A.; Lenisa, P.; Liebing, P.; Linden-Levy, L. A.; Lorenzon, W.; Lu, H.; Lu, J.; Lu, S.; Ma, B.-Q.; Maiheu, B.; Makins, N. C.; Mao, Y.; Marianski, B.; Marukyan, H.; Masoli, F.; Mexner, V.; Meyners, N.; Michler, T.; Mikloukho, O.; Miller, C. A.; Miyachi, Y.; Muccifora, V.; Nagaitsev, A.; Nappi, E.; Naryshkin, Y.; Nass, A.; Negodaev, M.; Nowak, W.-D.; Oganessyan, K.; Ohsuga, H.; Osborne, A.; Pickert, N.; Potterveld, D. H.; Raithel, M.; Reggiani, D.; Reimer, P. E.; Reischl, A.; Reolon, A. R.; Riedl, C.; Rith, K.; Rosner, G.; Rostomyan, A.; Rubacek, L.; Rubin, J.; Ryckbosch, D.; Salomatin, Y.; Sanjiev, I.; Savin, I.; Schäfer, A.; Schill, C.; Schnell, G.; Schüler, K. P.; Seele, J.; Seidl, R.; Seitz, B.; Shanidze, R.; Shearer, C.; Shibata, T.-A.; Shutov, V.; Sinram, K.; Sommer, W.; Stancari, M.; Statera, M.; Steffens, E.; Steijger, J. J.; Stenzel, H.; Stewart, J.; Stinzing, F.; Tait, P.; Tanaka, H.; Taroian, S.; Tchuiko, B.; Terkulov, A.; Trzcinski, A.; Tytgat, M.; Vandenbroucke, A.; van der Nat, P. B.; van der Steenhoven, G.; van Haarlem, Y.; Vetterli, M. C.; Vikhrov, V.; Vincter, M. G.; Vogel, C.; Volmer, J.; Wang, S.; Wendland, J.; Wilbert, J.; Smit, G. Ybeles; Ye, Y.; Ye, Z.; Yen, S.; Zihlmann, B.; Zupranski, P.
2005-01-01
Single-spin asymmetries for semi-inclusive electroproduction of charged pions in deep-inelastic scattering of positrons are measured for the first time with transverse target polarization. The asymmetry depends on the azimuthal angles of both the pion (ϕ) and the target spin axis (ϕS) about the virtual-photon direction and relative to the lepton scattering plane. The extracted Fourier component πUT is a signal of the previously unmeasured quark transversity distribution, in conjunction with the Collins fragmentation function, also unknown. The component πUT arises from a correlation between the transverse polarization of the target nucleon and the intrinsic transverse momentum of quarks, as represented by the previously unmeasured Sivers distribution function. Evidence for both signals is observed, but the Sivers asymmetry may be affected by exclusive vector meson production.
A portable high-field pulsed-magnet system for single-crystal x-ray scattering studies
International Nuclear Information System (INIS)
Islam, Zahirul; Lang, Jonathan C.; Ruff, Jacob P. C.; Ross, Kathryn A.; Gaulin, Bruce D.; Nojiri, Hiroyuki; Matsuda, Yasuhiro H.; Qu Zhe
2009-01-01
We present a portable pulsed-magnet system for x-ray studies of materials in high magnetic fields (up to 30 T). The apparatus consists of a split-pair of minicoils cooled on a closed-cycle cryostat, which is used for x-ray diffraction studies with applied field normal to the scattering plane. A second independent closed-cycle cryostat is used for cooling the sample to near liquid helium temperatures. Pulsed magnetic fields (∼1 ms in total duration) are generated by discharging a configurable capacitor bank into the magnet coils. Time-resolved scattering data are collected using a combination of a fast single-photon counting detector, a multichannel scaler, and a high-resolution digital storage oscilloscope. The capabilities of this instrument are used to study a geometrically frustrated system revealing strong magnetostrictive effects in the spin-liquid state.
Roflumilast - A reversible single-crystal to single-crystal phase transition at 50 °C
Viertelhaus, Martin; Holst, Hans Christof; Volz, Jürgen; Hummel, Rolf-Peter
2013-01-01
Roflumilast is a selective phosphodiesterase type 4 inhibitor and is marketed under the brand names Daxas®, Daliresp® and Libertec®. A phase transition of the drug substance roflumilast was observed at 50 °C. The low temperature form, the high temperature form and the phase transition were characterised by differential scanning calorimetry, variable temperature powder X-ray diffraction and single crystal X-ray diffraction, Raman spectroscopy and solid state NMR spectroscopy. The phase transition of roflumilast at 50 °C is completely reversible, the high temperature form cannot be stabilised by quench cooling and the phase transition does not influence the quality of the active pharmaceutical ingredient (API) and the drug product. It was observed to be a single crystal to single crystal phase transition.
Steelman, Zachary A; Eldridge, Will J; Weintraub, Jacob B; Wax, Adam
2017-12-01
The refractive index (RI) of biological materials is a fundamental parameter for the optical characterization of living systems. Numerous light scattering technologies are grounded in a quantitative knowledge of the refractive index at cellular and subcellular scales. Recent work in quantitative phase microscopy (QPM) has called into question the widely held assumption that the index of the cell nucleus is greater than that of the cytoplasm, a result which disagrees with much of the current literature. In this work, we critically examine the measurement of the nuclear and whole-cell refractive index using QPM, validating that nuclear refractive index is lower than that of cytoplasm in four diverse cell lines and their corresponding isolated nuclei. We further examine Mie scattering and phase-wrapping as potential sources of error in these measurements, finding they have minimal impact. Finally, we use simulation to examine the effects of incorrect RI assumptions on nuclear morphology measurements using angle-resolved scattering information. Despite an erroneous assumption of the nuclear refractive index, accurate measurement of nuclear morphology was maintained, suggesting that light scattering modalities remain effective. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
Application of light scattering to particle metrology in disperse two-phase flow
International Nuclear Information System (INIS)
Hamelin, P.
1986-01-01
The improvement of the knowledge of disperse-phase flow is interesting for many industrial sectors, and, e.g, the water-steam systems on which electric power generation is based in fossil fuel or nuclear power plants. Using a classical reference beam laser Doppler anemometer, an in-situ particle analyser has been designed to allow a simultaneous measurement of size and velocity of individual spherical particles within the 20-300 um range. Size measurement is based on the analysis of the light attenuation signal detected by a photodiode placed on the axis of the intense beam occurring when a particle crosses the probe volume. It is shown that when the laser beams are slightly unfocused in the probe volume, the shape and amplitude of the signal can be related to the particle trajectory and size. To justify these results, a simplified theoretical model of the forward scattering process in a gaussian beam is presented. In order to test numerical predictions, a set of basic experiments has been performed with glass spheres in a He-Ne laser beam. A good agreement between experimental measurements and theoretical results is shown, especially when particles are off center and out of the beam focal plane. This model has been used to simulate attenuation signals, to establish the relationship between particle size and signal amplitude, and to test the sensitivity of the method for off-center trajectories. Finally, the descriptions of the optical set up and the electronic device designed for signal processing and data acquisition are presented [fr
Akimov, D. Yu; Alexandrov, I. S.; Aleshin, V. I.; Belov, V. A.; Bolozdynya, A. I.; Burenkov, A. A.; Chepurnov, A. S.; Danilov, M. V.; Derbin, A. V.; Dmitrenko, V. V.; Dolgolenko, A. G.; Efremenko, Yu V.; Etenko, A. V.; Gromov, M. B.; Gulin, M. A.; Ivakhin, S. V.; Kantserov, V. A.; Kaplin, V. A.; Karelin, A. K.; Khromov, A. V.; Kirsanov, M. A.; Klimanov, S. G.; Kobyakin, A. S.; Konovalov, A. M.; Kovalenko, A. G.; Kopeikin, V. I.; Krakhmalova, T. D.; Kuchenkov, A. V.; Kumpan, A. V.; Litvinovich, E. A.; Lukyanchenko, G. A.; Machulin, I. N.; Martemyanov, V. P.; Nurakhov, N. N.; Rudik, D. G.; Saldikov, I. S.; Skorokhatov, M. D.; Sosnovtsev, V. V.; Stekhanov, V. N.; Sukhotin, S. V.; Tarasenkov, V. G.; Tikhomirov, G. V.; Zeldovich, O. Ya
2013-10-01
We propose to detect and to study neutrino neutral current coherent scattering off atomic nuclei with a two-phase emission detector using liquid xenon as a working medium. Expected signals and backgrounds are calculated for two possible experimental sites: the Kalinin Nuclear Power Plant in the Russian Federation and the Spallation Neutron Source at the Oak Ridge National Laboratory in the U.S.A. Both sites have advantages as well as limitations. The experiment looks feasible at either location.
Controlling geometric phase optically in a single spin in diamond
Yale, Christopher G.
Geometric phase, or Berry phase, is an intriguing quantum mechanical phenomenon that arises from the cyclic evolution of a quantum state. Unlike dynamical phases, which rely on the time and energetics of the interaction, the geometric phase is determined solely by the geometry of the path travelled in parameter space. As such, it is robust to certain types of noise that preserve the area enclosed by the path, and shows promise for the development of fault-tolerant logic gates. Here, we demonstrate the optical control of geometric phase within a solid-state spin qubit, the nitrogen-vacancy center in diamond. Using stimulated Raman adiabatic passage (STIRAP), we evolve a coherent dark state along `tangerine slice' trajectories on the Bloch sphere and probe these paths through time-resolved state tomography. We then measure the accumulated geometric phase through phase reference to a third ground spin state. In addition, we examine the limits of this control due to adiabatic breakdown as well as the longer timescale effect of far-detuned optical fields. Finally, we intentionally introduce noise into the experimental control parameters, and measure the distributions of the resulting phases to probe the resilience of the phase to differing types of noise. We also examine this robustness as a function of traversal time as well as the noise amplitude. Through these studies, we demonstrate that geometric phase is a promising route toward fault-tolerant quantum information processing. This work is supported by the AFOSR, the NSF, and the German Research Foundation.
Infrared dispersion analysis and Raman scattering spectra of taurine single crystals
Moreira, Roberto L.; Lobo, Ricardo P. S. M.; Dias, Anderson
2018-01-01
A comprehensive set of optical vibrational modes of monoclinic taurine crystals was determined by Raman scattering, and infrared reflectivity and transmission spectroscopies. By using appropriate scattering/reflection geometries, the vibrational modes were resolved by polarization and the most relevant modes of the crystal could be assigned. In particular, we were able to review the symmetry of the gerade modes and to resolve ambiguities in the literature. Owing to the non-orthogonal character of Bu modes in monoclinic crystals (lying on the optic axial plane), we carried out a generalized Lorentz dispersion analysis consisting of simultaneous adjust of infrared-reflectivity spectra at various light polarization angles. The Au modes (parallel to the C2-axis) were treated within the classical Lorentz model. The behavior of off-diagonal and diagonal terms of the complex dielectric tensors and the presence of anomalous dispersion were discussed as consequences of the low symmetry of the crystal.
Analysis of suspended solids by single-particle scattering. [for Lake Superior pollution monitoring
Diehl, S. R.; Smith, D. T.; Sydor, M.
1979-01-01
Light scattering by individual particulates is used in a multiple-detector system to categorize the composition of suspended solids in terms of broad particulate categories. The scattering signatures of red clay and taconite tailings, the two primary particulate contaminants in western Lake Superior, along with two types of asbestiform fibers, amphibole and chrysolite, were studied in detail. A method was developed to predict the concentration of asbestiform fibers in filtration plant samples for which electron microscope analysis was done concurrently. Fiber levels as low as 50,000 fibers/liter were optically detectable. The method has application in optical categorization of samples for remote sensing purposes and offers a fast, inexpensive means for analyzing water samples from filtration plants for specific particulate contaminants.
Heinisch, Christian; Wills, Jon B; Reid, Jonathan P; Tschudi, Theo; Tropea, Cameron
2009-11-14
The evaporation dynamics of stationary water droplets held within an electrodynamic trap are investigated in a nitrogen flow of variable velocity. In particular, the influence of the nitrogen gas flow on the temperature of the evaporating water droplets is studied. By applying a contact free measurement technique, based on spontaneous Raman scattering, time averaged and time resolved measurements of temperature in the droplet volume are compared. This technique determines the temperature from an intensity ratio in the OH stretching band of the Stokes-Raman scattering after calibration. The measured trends in temperature over the first 5 s of evaporation are found to be in agreement with theoretical calculations of the heat and mass transfer rates.
Chou, Ming-Dah; Suarez, Max J.; Ho, Chang-Hoi; Yan, Michael M.-H.; Lee, Kyu-Tae
1998-02-01
Parameterizations for cloud single-scattering properties and the scaling of optical thickness in a partial cloudiness condition have been developed for use in atmospheric models. Cloud optical properties are parameterized for four broad bands in the solar (or shortwave) spectrum; one in the ultraviolet and visible region and three in the infrared region. The extinction coefficient, single-scattering albedo, and asymmetry factor are parameterized separately for ice and water clouds. Based on high spectral-resolution calculations, the effective single-scattering coalbedo of a broad band is determined such that errors in the fluxes at the top of the atmosphere and at the surface are minimized. This parameterization introduces errors of a few percent in the absorption of shortwave radiation in the atmosphere and at the surface.Scaling of the optical thickness is based on the maximum-random cloud-overlapping approximation. The atmosphere is divided into three height groups separated approximately by the 400- and 700-mb levels. Clouds are assumed maximally overlapped within each height group and randomly overlapped among different groups. The scaling is applied only to the maximally overlapped cloud layers in individual height groups. The scaling as a function of the optical thickness, cloud amount, and the solar zenith angle is derived from detailed calculations and empirically adjusted to minimize errors in the fluxes at the top of the atmosphere and at the surface. Different scaling is used for direct and diffuse radiation. Except for a large solar zenith angle, the error in fluxes introduced by the scaling is only a few percent. In terms of absolute error, it is within a few watts per square meter.
Development of single shot 1D-Raman scattering measurements for flames
Biase, Amelia; Uddi, Mruthunjaya
2017-11-01
The majority of energy consumption in the US comes from burning fossil fuels which increases the concentration of carbon dioxide in the atmosphere. The increasing concentration of carbon dioxide in the atmosphere has negative impacts on the environment. One solution to this problem is to study the oxy-combustion process. A pure oxygen stream is used instead of air for combustion. Products contain only carbon dioxide and water. It is easy to separate water from carbon dioxide by condensation and the carbon dioxide can be captured easily. Lower gas volume allows for easier removal of pollutants from the flue gas. The design of a system that studies the oxy-combustion process using advanced laser diagnostic techniques and Raman scattering measurements is presented. The experiments focus on spontaneous Raman scattering. This is one of the few techniques that can provide quantitative measurements of the concentration and temperature of different chemical species in a turbulent flow. The experimental design and process of validating the design to ensure the data is accurate is described. The Raman data collected form an experimental data base that is used for the validation of spontaneous Raman scattering in high pressure environments for the oxy-combustion process. NSF EEC 1659710.
International Nuclear Information System (INIS)
Abis, S.; Fiorini, P.; Caciuffo, R.; Coppola, R.
1987-01-01
A study was recently performed to investigate, by means of Small Angle Neutron Scattering (SANS), the precipitation of Mg 2 Si phase in a polycrystalline sample of a high purity Al-Mg-Si alloy. This kind of alloys, of great industrial interest, are characterized by the well known precipitation sequence: α SS -G.P.-β'-β(Mg 2 Si) as pointed out since 1961. SANS is able to supply relevant information on the size distribution of precipitates induced by thermal treatment of the quench from solubilization temperature. In particular it was shown that the precipitate volume fraction obtained from the size distribution function deduced from SANS measurements was in agreement with the results of resistivity measurements which, as well known, precise quantitative information about the depletion of the solid solution during isothermal annealing. In this paper we study a single crystal by means of a SANS measurement performed with the same experimental facility (D17 at ILL-Grenoble), and try to exploit all information arising from the regular orientation of the precipitates by means of a two-dimensional pattern analysis accounting for the directional anisotropy of the scattering profile. 6 refs., 3 figs
Saleh, Khaldoun; Merrer, Pierre-Henri; Llopis, Olivier; Cibiel, Gilles
2012-02-15
Nonlinear phenomena occurring in an optical fiber ring resonator featuring ultrahigh Q factor are experimentally studied. The laser is locked onto the resonator, and the optical power induced in the resonator is controlled. The onset of the first stimulated Brillouin scattering wave occurs at an optical input power as low as -9 dBm in these resonators. When the resonator is used as the frequency reference device in an optoelectronic oscillator (OEO), it has been found that these parasitic signals mix with the OEO signal and degrade its phase noise. More than 20 dB improvement of the OEO phase noise has been demonstrated by limiting these nonlinear optical effects.
Donatelli, Jeffrey J; Sethian, James A; Zwart, Peter H
2017-07-11
Free-electron lasers now have the ability to collect X-ray diffraction patterns from individual molecules; however, each sample is delivered at unknown orientation and may be in one of several conformational states, each with a different molecular structure. Hit rates are often low, typically around 0.1%, limiting the number of useful images that can be collected. Determining accurate structural information requires classifying and orienting each image, accurately assembling them into a 3D diffraction intensity function, and determining missing phase information. Additionally, single particles typically scatter very few photons, leading to high image noise levels. We develop a multitiered iterative phasing algorithm to reconstruct structural information from single-particle diffraction data by simultaneously determining the states, orientations, intensities, phases, and underlying structure in a single iterative procedure. We leverage real-space constraints on the structure to help guide optimization and reconstruct underlying structure from very few images with excellent global convergence properties. We show that this approach can determine structural resolution beyond what is suggested by standard Shannon sampling arguments for ideal images and is also robust to noise.
Min, S L; Gomez, A
1996-08-20
A technique is described and demonstrated to measure the size of spherical particles of known index of refraction by laser light scattering with an accuracy of better than 1%. This technique entails imaging the angular scattering intensity onto a photodiode array and applying a fast Fourier transform to the array output to obtain a frequency and phase corresponding to the number and angular position of the scattering lobes. Errors associated with particle trajectory effects and changes in the index of refraction are also considered. Results are not affected by the former, whereas variations of the refractive index by 2%, as may be typical, for example, of the transient heat up of a liquid hydrocarbon droplet, cause a deterioration of sizing accuracy to approximately 3%. The technique can in principle be applied in real time at data rates as high as 20-30 kHz with a modest equipment investment. Therefore, the measurement of droplet evaporation rates in dilute sprays with unprecedented accuracy appears to be feasible.
Use of Single-Layer g-C3N4/Ag Hybrids for Surface-Enhanced Raman Scattering (SERS)
Jiang, Jizhou; Zou, Jing; Wee, Andrew Thye Shen; Zhang, Wenjing
2016-01-01
Surface-enhanced Raman scattering (SERS) substrates with high activity and stability are desirable for SERS sensing. Here, we report a new single atomic layer graphitic-C3N4 (S-g-C3N4) and Ag nanoparticles (NPs) hybrid as high-performance SERS substrates. The SERS mechanism of the highly stable S-g-C3N4/Ag substrates was systematically investigated by a combination of experiments and theoretical calculations. From the results of XPS and Raman spectroscopies, it was found that there was a stro...
3D nanostar dimers with a sub-10-nm gap for single-/few-molecule surface-enhanced raman scattering
Chirumamilla, Manohar
2014-01-22
Plasmonic nanostar-dimers, decoupled from the substrate, have been fabricated by combining electron-beam lithography and reactive-ion etching techniques. The 3D architecture, the sharp tips of the nanostars and the sub-10 nm gap size promote the formation of giant electric-field in highly localized hot-spots. The single/few molecule detection capability of the 3D nanostar-dimers has been demonstrated by Surface-Enhanced Raman Scattering. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
DEFF Research Database (Denmark)
Guan, Pengyu; Da Ros, Francesco; Lillieholm, Mads
2016-01-01
We demonstrate simultaneous phase regeneration of 16-WDM DPSK channels using optical Fourier transformation and a single phase-sensitive amplifier. The BERs of 16-WDM×10-Gbit/s phase noise degraded DPSK signals are improved by 0.4-1.3 orders of magnitude......We demonstrate simultaneous phase regeneration of 16-WDM DPSK channels using optical Fourier transformation and a single phase-sensitive amplifier. The BERs of 16-WDM×10-Gbit/s phase noise degraded DPSK signals are improved by 0.4-1.3 orders of magnitude...
Umhauer, H; Bottlinger, M
1991-11-20
To evaluate quantitatively the influence exerted by the shape and structure of nonspherical, nonideal particles on the results of single-particle scattered-light size analysis, measurements were conducted with individual particles of different materials (glass, limestone, and quartz). For this purpose, the particles were suspended in an electrodynamic balance and repeatedly passed through the analyzer's measuring volume with a continually changing random orientation. The scattered-light signal spectra thus obtained specify the probability with which a certain pulse height is induced when the particle passes once through the measuring volume at a given coincidental orientation. The spectra reflect the material-characteristic influence. They allow the loss of resolution of common scattered-light size analyses to be assessed and algorithms (matrices) to be compiled with which the shape and structure influence may be mathematically eliminated. Because a shape and structure independent size parameter is also determined from the individual particles, exact calibration curves can be derived in which the shape and structure influence are incorporated.
Composite single crystal silicon scan mirror substrates, Phase I
National Aeronautics and Space Administration — Single crystal silicon is a desirable mirror substrate for scan mirrors in space telescopes. As diameters of mirrors become larger, existing manufacturing...
Single phase and two phase erosion corrosion in broilers of gas-cooled reactors
International Nuclear Information System (INIS)
Harrison, G.S.; Fountain, M.J.
1988-01-01
Erosion-corrosion is a phenomenon causing metal wastage in a variety of locations in water and water-steam circuits throughout the power generation industry. Erosion-corrosion can occur in a number of regions of the once-through boiler designs used in the later Magnox and AGR type of gas cooled nuclear reactor. This paper will consider two cases of erosion-corrosion damage (single and two phase) in once through boilers of gas cooled reactors and will describe the solutions that have been developed. The single phase problem is associated with erosion-corrosion damage of mild steel downstream of a boiler inlet flow control orifice. With metal loss rates of up to 1 mm/year at 150 deg. C and pH in the range 9.0-9.4 it was found that 5 μg/kg oxygen was sufficient to reduce erosion-corrosion rates to less than 0.02 mm/year. A combined oxygen-ammonia-hydrazine feedwater regime was developed and validated to eliminate oxygen carryover and hence give protection from stress corrosion in the austenitic section of the AGR once through boiler whilst still providing erosion-corrosion control. Two phase erosion-corrosion tube failures have occurred in the evaporator of the mild steel once through boilers of the later Magnox reactors operating at pressures in the range 35-40 bar. Rig studies have shown that amines dosed in the feedwater can provide a significant reduction in metal loss rates and a tube lifetime assessment technique has been developed to predict potential tube failure profiles in a fully operational boiler. The solutions identified for both problems have been successfully implemented and the experience obtained following implementation including any problems or other benefits arising from the introduction of the new regimes will be presented. Methods for monitoring and evaluating the efficiency of the solutions have been developed and the results from these exercises will also be discussed. Consideration will also be given to the similarities in the metal loss
International Nuclear Information System (INIS)
Kamphuis, C.; Beekman, F.J.; Van Rijk, P.P.; Viergever, M.A.
1998-01-01
Three-dimensional (3D) iterative maximum likelihood expectation maximization (ML-EM) algorithms for single-photon emission tomography (SPET) are capable of correcting image-degrading effects of non-uniform attenuation, distance-dependent camera response and patient shape-dependent scatter. However, the resulting improvements in quantitation, resolution and signal-to-noise ratio (SNR) are obtained at the cost of a huge computational burden. This paper presents a new acceleration method for ML-EM: dual matrix ordered subsets (DM-OS). DM-OS combines two acceleration methods: (a) different matrices for projection and back-projection and (b) ordered subsets of projections. DM-OS was compared with ML-EM on simulated data and on physical thorax phantom data, for both 180 and 360 orbits. Contrast, normalized standard deviation and mean squared error were calculated for the digital phantom experiment. DM-OS resulted in similar image quality to ML-EM, even for speed-up factors of 200 compared to ML-EM in the case of 120 projections. The thorax phantom data could be reconstructed 50 times faster (60 projections) using DM-OS with preservation of image quality. ML-EM and DM-OS with scatter compensation showed significant improvement of SNR compared to ML-EM without scatter compensation. Furthermore, inclusion of complex image formation models in the computer code is simplified in the case of DM-OS. It is thus shown that DM-OS is a fast and relatively simple algorithm for 3D iterative scatter compensation, with similar results to conventional ML-EM, for both 180 and 360 acquired data. (orig.)
Directory of Open Access Journals (Sweden)
Menxi Xie
2017-06-01
Full Text Available High performance synchronization methord is citical for grid connected power converter. For single-phase system, power based phase-locked loop(pPLL uses a multiplier as phase detector(PD. As single-phase grid voltage is distorted, the phase error information contains ac disturbances oscillating at integer multiples of fundamental frequency which lead to detection error. This paper presents a new scheme based on moving average filter(MAF applied in-loop of pPLL. The signal characteristic of phase error is dissussed in detail. A predictive rule is adopted to compensate the delay induced by MAF, thus achieving fast dynamic response. In the case of frequency deviate from nomimal, estimated frequency is fed back to adjust the filter window length of MAF and buffer size of predictive rule. Simulation and experimental results show that proposed PLL achieves good performance under adverse grid conditions.
Analysis of phase-locked loop influence on the stability of single-phase grid-connected inverter
DEFF Research Database (Denmark)
Zhang, Chong; Wang, Xiongfei; Blaabjerg, Frede
2015-01-01
A controlled power inverter can cause instability at the point of common coupling (PCC) with its output filter and the grid. This paper analyzes the influence of the Phase-Locked Loop (PLL) on the output admittance of single-phase current-controlled inverters with different grid stiffness. It shows...
Energy Technology Data Exchange (ETDEWEB)
Waidyawansa, Dinayadura Buddhini [Ohio Univ., Athens, OH (United States)
2013-08-01
The beam normal single spin asymmetry generated in the scattering of transversely polarized electrons from unpolarized nucleons is an observable of the imaginary part of the two-photon exchange process. Moreover, it is a potential source of false asymmetry in parity violating electron scattering experiments. The Q{sub weak} experiment uses parity violating electron scattering to make a direct measurement of the weak charge of the proton. The targeted 4% measurement of the weak charge of the proton probes for parity violating new physics beyond the Standard Model. The beam normal single spin asymmetry at Q{sub weak} kinematics is at least three orders of magnitude larger than 5 ppb precision of the parity violating asymmetry. To better understand this parity conserving background, the Q{sub weak} Collaboration has performed elastic scattering measurements with fully transversely polarized electron beam on the proton and aluminum. This dissertation presents the analysis of the 3% measurement (1.3% statistical and 2.6% systematic) of beam normal single spin asymmetry in electronproton scattering at a Q2 of 0.025 (GeV/c)2. It is the most precise existing measurement of beam normal single spin asymmetry available at the time. A measurement of this precision helps to improve the theoretical models on beam normal single spin asymmetry and thereby our understanding of the doubly virtual Compton scattering process.
Sun, B.; Yang, P.; Kattawar, G. W.; Zhang, X.
2017-12-01
The ice cloud single-scattering properties can be accurately simulated using the invariant-imbedding T-matrix method (IITM) and the physical-geometric optics method (PGOM). The IITM has been parallelized using the Message Passing Interface (MPI) method to remove the memory limitation so that the IITM can be used to obtain the single-scattering properties of ice clouds for sizes in the geometric optics regime. Furthermore, the results associated with random orientations can be analytically achieved once the T-matrix is given. The PGOM is also parallelized in conjunction with random orientations. The single-scattering properties of a hexagonal prism with height 400 (in units of lambda/2*pi, where lambda is the incident wavelength) and an aspect ratio of 1 (defined as the height over two times of bottom side length) are given by using the parallelized IITM and compared to the counterparts using the parallelized PGOM. The two results are in close agreement. Furthermore, the integrated single-scattering properties, including the asymmetry factor, the extinction cross-section, and the scattering cross-section, are given in a completed size range. The present results show a smooth transition from the exact IITM solution to the approximate PGOM result. Because the calculation of the IITM method has reached the geometric regime, the IITM and the PGOM can be efficiently employed to accurately compute the single-scattering properties of ice cloud in a wide spectral range.
Structure and magnetism of single-phase epitaxial gamma '-Fe4N
Costa-Kramer, JL; Borsa, DM; Garcia-Martin, JM; Martin-Gonzalez, MS; Boerma, DO; Briones, F
Single phase epitaxial pure gamma(')-Fe4N films are grown on MgO (001) by molecular beam epitaxy of iron in the presence of nitrogen obtained from a radio frequency atomic source. The epitaxial, single phase nature of the films is revealed by x-ray diffraction and by the local magnetic environment
new topology for single-phase, three-level, spwm vsi with lc filter
African Journals Online (AJOL)
level PWM inverter. However, this is not the case with single-phase PWM inverters. In these days, the popular single-phase inverters adopt the full-bridge type using approximate sinusoidal modulation technique. The output voltage in them has two values: zero and pos- itive supply dc voltage levels in the positive half cycle.
Torque Analysis With Saturation Effects for Non-Salient Single-Phase Permanent-Magnet Machines
DEFF Research Database (Denmark)
Lu, Kaiyuan; Ritchie, Ewen
2011-01-01
The effects of saturation on torque production for non-salient, single-phase, permanent-magnet machines are studied in this paper. An analytical torque equation is proposed to predict the instantaneous torque with saturation effects. Compared to the existing methods, it is computationally faster......-element results, and experimental results obtained on a prototype single-phase permanent-magnet machine....
Kastrisianaki-Guyton, E S; Chen, L; Rogers, S E; Cosgrove, T; van Duijneveldt, J S
2016-06-15
Aqueous dispersions of single-walled carbon nanotubes are often made using sodium dodecylsulfate (SDS), which adsorbs to the nanotube surface to stabilise them. Despite SDS being commonly used with single-walled carbon nanotubes, there is no consensus on the structure of the adsorbed layer. Small-angle neutron and X-ray scattering results reported here show that the data can be fitted to a relatively simple core-shell cylinder model, consistent with a polydisperse nanotube core of radius 10Å, surrounded by an adsorbed surfactant layer of thickness 18Å and volume fraction of 0.5. This is consistent with small nanotube bundles surrounded by an adsorbed layer of extended SDS molecules. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.
Single pulse vibrational Raman scattering by a broadband KrF excimer laser in a hydrogen-air flame
Pitz, Robert W.; Wehrmeyer, Joseph A.; Bowling, J. M.; Cheng, Tsarng-Sheng
1990-01-01
Spontaneous vibrational Raman scattering (VRS) is produced by a broadband excimer laser at 248 nm (KrF) in a H2-air flame, and VRS spectra are recorded for lean, stoichiometric, and rich flames. Except at very lean flame conditions, laser-induced fluorescence (LIF) processes interfere with VRS Stokes lines from H2, H2O, and O2. No interference is found for the N2 Stokes and N2 anti-Stokes lines. In a stoichiometric H2/air flame, single-pulse measurements of N2 concentration and temperature (by the VRS Stokes to anti-Stokes ratio) have a relative standard deviation of 7.7 and 10 percent, respectively. These single pulse measurement errors compare well with photon statistics calculations using measured Raman cross sections.
Energy Technology Data Exchange (ETDEWEB)
Song, Guo-Zhu; Zhang, Mei; Ai, Qing; Yang, Guo-Jian [Department of Physics, Applied Optics Beijing Area Major Laboratory, Beijing Normal University, Beijing 100875 (China); Alsaedi, Ahmed; Hobiny, Aatef [NAAM-Research Group, Department of Mathematics, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589 (Saudi Arabia); Deng, Fu-Guo, E-mail: fgdeng@bnu.edu.cn [Department of Physics, Applied Optics Beijing Area Major Laboratory, Beijing Normal University, Beijing 100875 (China); NAAM-Research Group, Department of Mathematics, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589 (Saudi Arabia)
2017-03-15
We propose a heralded quantum repeater based on the scattering of photons off single emitters in one-dimensional waveguides. We show the details by implementing nonlocal entanglement generation, entanglement swapping, and entanglement purification modules with atoms in waveguides, and discuss the feasibility of the repeater with currently achievable technology. In our scheme, the faulty events can be discarded by detecting the polarization of the photons. That is, our protocols are accomplished with a fidelity of 100% in principle, which is advantageous for implementing realistic long-distance quantum communication. Moreover, additional atomic qubits are not required, but only a single-photon medium. Our scheme is scalable and attractive since it can be realized in solid-state quantum systems. With the great progress on controlling atom-waveguide systems, the repeater may be very useful in quantum information processing in the future.
Energy Technology Data Exchange (ETDEWEB)
Klein, Stephen A.; McCoy, Renata B.; Morrison, Hugh; Ackerman, Andrew S.; Avramov, Alexander; de Boer, Gijs; Chen, Mingxuan; Cole, Jason N.S.; Del Genio, Anthony D.; Falk, Michael; Foster, Michael J.; Fridlind, Ann; Golaz, Jean-Christophe; Hashino, Tempei; Harrington, Jerry Y.; Hoose, Corinna; Khairoutdinov, Marat F.; Larson, Vincent E.; Liu, Xiaohong; Luo, Yali; McFarquhar, Greg M.; Menon, Surabi; Neggers, Roel A. J.; Park, Sungsu; Poellot, Michael R.; Schmidt, Jerome M.; Sednev, Igor; Shipway, Ben J.; Shupe, Matthew D.; Spangenberg, Douglas A.; Sud, Yogesh C.; Turner, David D.; Veron, Dana E.; von Salzen, Knut; Walker, Gregory K.; Wang, Zhien; Wolf, Audrey B.; Xie, Shaocheng; Xu, Kuan-Man; Yang, Fanglin; Zhang, Gong
2009-02-02
Results are presented from an intercomparison of single-column and cloud-resolving model simulations of a cold-air outbreak mixed-phase stratocumulus cloud observed during the Atmospheric Radiation Measurement (ARM) program's Mixed-Phase Arctic Cloud Experiment. The observed cloud occurred in a well-mixed boundary layer with a cloud top temperature of -15 C. The observed average liquid water path of around 160 g m{sup -2} was about two-thirds of the adiabatic value and much greater than the average mass of ice crystal precipitation which when integrated from the surface to cloud top was around 15 g m{sup -2}. The simulations were performed by seventeen single-column models (SCMs) and nine cloud-resolving models (CRMs). While the simulated ice water path is generally consistent with the observed values, the median SCM and CRM liquid water path is a factor of three smaller than observed. Results from a sensitivity study in which models removed ice microphysics suggest that in many models the interaction between liquid and ice-phase microphysics is responsible for the large model underestimate of liquid water path. Despite this general underestimate, the simulated liquid and ice water paths of several models are consistent with the observed values. Furthermore, there is evidence that models with more sophisticated microphysics simulate liquid and ice water paths that are in better agreement with the observed values, although considerable scatter is also present. Although no single factor guarantees a good simulation, these results emphasize the need for improvement in the model representation of mixed-phase microphysics.
Paiva, Joana S; Ribeiro, Rita S R; Cunha, João P S; Rosa, Carla C; Jorge, Pedro A S
2018-02-27
Recent trends on microbiology point out the urge to develop optical micro-tools with multifunctionalities such as simultaneous manipulation and sensing. Considering that miniaturization has been recognized as one of the most important paradigms of emerging sensing biotechnologies, optical fiber tools, including Optical Fiber Tweezers (OFTs), are suitable candidates for developing multifunctional small sensors for Medicine and Biology. OFTs are flexible and versatile optotools based on fibers with one extremity patterned to form a micro-lens. These are able to focus laser beams and exert forces onto microparticles strong enough (piconewtons) to trap and manipulate them. In this paper, through an exploratory analysis of a 45 features set, including time and frequency-domain parameters of the back-scattered signal of particles trapped by a polymeric lens, we created a novel single feature able to differentiate synthetic particles (PMMA and Polystyrene) from living yeasts cells. This single statistical feature can be useful for the development of label-free hybrid optical fiber sensors with applications in infectious diseases detection or cells sorting. It can also contribute, by revealing the most significant information that can be extracted from the scattered signal, to the development of a simpler method for particles characterization (in terms of composition, heterogeneity degree) than existent technologies.
Berg, Matthew J; Hill, Steven C; Videen, Gorden; Gurton, Kristan P
2010-04-26
This work describes the design and use of an optical apparatus to measure the far-field elastic light-scattering pattern for a single particle over two angular-dimensions. A spatial filter composed of a mirror with a small through-hole is used to enable collection of the pattern uncommonly close to the forward direction; to within tenths of a degree. Minor modifications of the design allow for the simultaneous measurement of a particle's image along with its two-dimensional scattering pattern. Example measurements are presented involving single micrometer-sized glass spherical particles confined in an electrodynamic trap and a dilute suspension of polystyrene latex particles in water. A small forward-angle technique, called Guinier analysis, is used to determine a particle-size estimate directly from the measured pattern without a priori knowledge of the particle refractive index. Comparison of these size estimates to those obtained by fitting the measurements to Mie theory reveals relative errors low as 2%.
Single Crystal Bimorph Array Driven Deformable Mirrors, Phase I
National Aeronautics and Space Administration — This Small Business Innovation Research (SBIR) Phase I project will research a novel deformable mirror design for NASA adaptive optics telescope applications . The...
Archer, J.; Kolwas, M.; Jakubczyk, D.; Derkachov, G.; Woźniak, M.; Kolwas, K.
2017-11-01
We report on observation of well-pronounced characteristic features of elastic light scattering of evaporating solution and suspension microdroplet of the anionic surfactant sodium dodecyl sulfate (SDS) and colloidal silica (SiO2) nanospheres in diethylene glycol (DEG) during SDS surface layer and structure formation (crystallization). For pure DEG/SDS solution droplet evaporation process, characteristic evaporation transitions manifested in the evolution of the droplet radius, a(t) for all the SDS concentrations (C = 20 mM, 40 mM and 100 mM) studied as well as well-pronounced intensity signals characterizing SDS soft gel-solid transitions for initial SDS concentrations, C > 40 mM. In the case of microdroplets composed of DEG/SDS with controlled addition of colloidal silica, the intensity fluctuations were enhanced and had profiles dependent on the initial composition of the suspension. Exemplary wet droplets at the initial evaporation stages and final dry aggregates of SDS and SDS/SiO2 were deposited on a substrate and observed with Scanning Electron Microscopy (SEM). Features of the deposited structures correlate well with the elastic scattered light measurements characterizing the drying processes.
Lewis, Aaron
2007-03-01
Raman spectroscopy is an effective tool for the identification and analysis of molecular components of complex materials. The spatial resolution of Raman spectroscopy is limited by the wavelength of the light. One approach to overcome this drawback is Surface Enhanced Raman Scattering (SERS). This technique uses nanometric interactions between metal structures and surfaces to effect enhancement of the Raman signals. An important mechanism for enhancement originates from an electrostatic lightning rod effect due to the excitation of localized surface plasmon resonances. This is accomplished in a scanned probe microscopy context by employing an ultra-sharp metalized tip that is brought into a focused laser spot on the sample surface thereby enhancing the Raman signal. In this technique also known as Tip Enhanced Raman Scattering (TERS) the electrical field is locally enhanced near the sharp metalized tip. Rastering the sample should then allow for Raman imaging with nanometric resolution. Within this context it will be shown that multiple probe scanned probe microscopes have considerable potential in such tip enhanced applications.
Vegso, Karol; Siffalovic, Peter; Jergel, Matej; Nadazdy, Peter; Nadazdy, Vojtech; Majkova, Eva
2017-03-08
Solvent annealing is an efficient way of phase separation in polymer-fullerene blends to optimize bulk heterojunction morphology of active layer in polymer solar cells. To track the process in real time across all relevant stages of solvent evaporation, laboratory-based in situ small- and wide-angle X-ray scattering measurements were applied simultaneously to a model P3HT:PCBM blend dissolved in dichlorobenzene. The PCBM molecule agglomeration starts at ∼7 wt % concentration of solid content of the blend in solvent. Although PCBM agglomeration is slowed-down at ∼10 wt % of solid content, the rate constant of phase separation is not changed, suggesting agglomeration and reordering of P3HT molecular chains. Having the longest duration, this stage most affects BHJ morphology. Phase separation is accelerated rapidly at concentration of ∼25 wt %, having the same rate constant as the growth of P3HT crystals. P3HT crystallization is driving force for phase separation at final stages before a complete solvent evaporation, having no visible temporal overlap with PCBM agglomeration. For the first time, such a study was done in laboratory demonstrating potential of the latest generation table-top high-brilliance X-ray source as a viable alternative before more sophisticated X-ray scattering experiments at synchrotron facilities are performed.
Void fraction measurements in two-phase flow by transmission and scattering of a neutrons beam
International Nuclear Information System (INIS)
Souza, M.C.L.
1984-01-01
Calibration curves have been obtained which supply average values of void fraction (α) of water-steam two-phase mixtures for bubble, slug, annular and invert annular flow states. The measurements were carried out in simulated models of lucite-air for the steady-state, using the techniques of transmission and diffusion of a thermal neutrons beam. The calibration curves obtained were used for measurements of void fraction in a circuit containing two-phase water-air mixtures, in upward concurrent flow, for slug flow (P sub(max) = 1,06 bar) and annular flow (P sub(max) = 1,33 bar), using the same techniques. In both of the systems, a test section made up of an aluminium (99,9%) tube was used with internal diameter of 25,25 mm and 2,0 mm wall thichness. The beam of neutrons was obtained from a 5 Ci isotopic Am-Be source, thermalised in a cylindrical moderator of paraffin of 500 mm diameter (with H/D=1) which was covered by 2 mm thick cadmium sheets and having in its centre a parallepeliped made from high density polyethilene with the dimensions 240 x 240 x 144 mm. The neutrons escape through a rectangular collimator of 53,0 x 25,25 mm, with a length of 273 mm cut out of a single block of borated paraffin (32% of H 3 BO 3 ). The experimental results are in good agreement with theorical models in published literature. (Author) [pt
Pressure-induced topological phase transitions and structural transition in 1T-TiTe2 single crystal
Zhang, Min; Wang, Xiangqi; Rahman, Azizur; Zeng, Qunsong; Huang, Da; Dai, Rucheng; Wang, Zhongping; Zhang, Zengming
2018-01-01
High pressure in situ Raman scattering and electrical resistivity measurements were performed to investigate the phase transitions in a semimetal 1T-TiTe2 single crystal up to 17 GPa. Combining anomalous experimental results with the electronic band structures and Z2 topological invariants in calculations, two topological phase transitions and one structural phase transition were confirmed at 1.7 GPa, 3 GPa, and 8 GPa, respectively. These two topological transformations are due to the enhanced orbital hybridization followed by a few of band inversions near the Fermi level, and the further parity analysis manifested that the phases II and III correspond to a strong topological state and a weak topological state, respectively. The rich topology variation of 1T-TiTe2 under high pressure provides a potential candidate for understanding the relevant topology physics and probable applications. The current results also demonstrate that Raman spectroscopy and electrical transport measurements are efficient tools to detect the topological phase transition under high pressure.
International Nuclear Information System (INIS)
Stirling, W.G.; Perry, S.C.
1996-01-01
We outline the theoretical and experimental background to neutron scattering studies of critical phenomena at magnetic and structural phase transitions. The displacive phase transition of SrTiO 3 is discussed, along with examples from recent work on magnetic materials from the rare-earth (Ho, Dy) and actinide (NpAs, NpSb, USb) classes. The impact of synchrotron X-ray scattering is discussed in conclusion. (author) 13 figs., 18 refs
Energy Technology Data Exchange (ETDEWEB)
Stirling, W.G. [Liverpool Univ., Dep. of Physics, Liverpool (United Kingdom); Perry, S.C. [Keele Univ. (United Kingdom). Dept. of Physics
1996-12-31
We outline the theoretical and experimental background to neutron scattering studies of critical phenomena at magnetic and structural phase transitions. The displacive phase transition of SrTiO{sub 3} is discussed, along with examples from recent work on magnetic materials from the rare-earth (Ho, Dy) and actinide (NpAs, NpSb, USb) classes. The impact of synchrotron X-ray scattering is discussed in conclusion. (author) 13 figs., 18 refs.
1.26 Single Frequency Fiber Laser, Phase II
National Aeronautics and Space Administration — This proposal is for the development of an innovative compact, high power, and extremely reliable 1.26 micron Ho-doped single frequency fiber laser. The proposed...
1.26 Single Frequency Fiber Laser, Phase I
National Aeronautics and Space Administration — This proposal is for the development of an innovative compact, high power, and extremely reliable 1.26 micron Ho-doped single frequency fiber laser. The proposed...
Single Molecule Scanning of DNA Radiation Oxidative Damage, Phase I
National Aeronautics and Space Administration — This proposal will develop an assay to map genomic DNA, at the single molecule level and in a nanodevice, for oxidative DNA damage arising from radiation exposure;...
Natural circulation in single-phase and two-phase flow
International Nuclear Information System (INIS)
Cheung, F.B.; El-Genk, M.S.
1989-01-01
Natural circulation usually arises in a closed loop between a heat source and a heat sink were the fluid motion is driven by density difference. It may also occur in enclosures or cavities where the flow is induced primarily by temperature or concentration gradients within the fluid. The subject has recently received special attention by the heat transfer and nuclear reactor safety communities because of it importance to the areas of energy extraction, decay, heat removal in nuclear reactors, solar and geothermal heating, and cooling of electronic equipment. Although many new results and physical insights have been gained of the various natural circulation phenomena, a number of critical issues remain unresolved. These include, for example, transition from laminar to turbulent flow, buoyancy-induced turbulent flow modeling, change of flow regimes, flow field visualization, variable property effects, and flow instability. This symposium volume contains papers presented in the Natural Circulation in Single-Phase and Two-Phase Flow session at the 1989 Winter Annual Meeting of ASME, by authors from different countries including the United States, Japan, Canada, and Brazil. The papers deal with experimental and theoretical studies as well as state-of-the-art reviews, covering a broad spectrum of topics in natural circulation including: variable-conductance thermosyphons, microelectronic chip cooling, natural circulation in anisotropic porous media and in cavities, heat transfer in flat plat solar collectors, shutdown heat removal in fast reactors, cooling of light-water and heavy-water reactors. The breadth of papers contained in this volume clearly reflect the importance of the current interest in natural circulation as a means for passive cooling and heating
Small angle neutron scattering study of U(VI) third phase formation ...
Indian Academy of Sciences (India)
nuclear fuel cycle because they can extract actinides over a wide range of acidi- ties (0.5 M–6 M). But these extractants form third phase when used along with commonly used diluents like dodecane [1,2]. The third phase formation, i.e. two organic phases and one aqueous phase, in solvent extraction experiments can be.
Polymer boosting effect in the droplet phase studied by small-angle neutron scattering
Frielinghaus, H; Allgaier, J; Richter, D; Jakobs, B; Sottmann, T; Strey, R
2002-01-01
Small-angle neutron-scattering experiments were performed in order to obtain the six partial scattering functions of a droplet microemulsion containing water, decane, C sub 1 sub 0 E sub 4 surfactant and PEP sub 5 -PEO sub 8 sub 0. We systematically varied the contrast around the polymer contrast, where only the polymer becomes visible, and we also measured bulk and film contrasts. With the singular value decomposition method we could extract the desired six partial scattering functions from the 15 measured spectra. We find a sphere-shell-shell structure of the droplets, where the innermost sphere consists of oil, the middle shell of surfactant and the outer shell is a depletion zone where the polymer is almost not present. (orig.)
Directory of Open Access Journals (Sweden)
Krishnan Arthishri
2017-05-01
Full Text Available In this study, a three-phase diode bridge rectifier and a single-phase voltage source inverter topology has been proposed for feeding single-phase utility grid employing a three-phase induction generator fed from wind energy. A self-excited induction generator configuration has been chosen for wide speed operation of wind turbine system, which gives the scope for extracting maximum power available in the wind. In addition to maximum power point tracking (MPPT, the generator can be loaded to its rated capacity for feeding single-phase utility grid using a three-phase induction machine, whereas it is not possible with existing configurations because of the absence of power converters. For the proposed system, MPPT algorithm has been devised by continuously monitoring the grid current and a proportional resonant controller has been employed for grid synchronisation of voltage source inverter with single-phase grid. A MATLAB/Simulink model of the proposed system has been developed to ascertain its successful working by predetermining the overall performance characteristics. The present proposal has also been tested with sag, swell and distortion in the grid voltage. The control strategy has been implemented using field programmable gate array (FPGA controller with modularised programming approach. The efficacy of the system has been demonstrated with the results obtained from an experimental set-up in the laboratory.
Batley, J Richard; Kalmus, George Ernest; Lazzeroni, C; Munday, D J; Slater, M W; Wotton, S A; Arcidiacono, R; Bocquet, G; Cabibbo, Nicola; Ceccucci, A; Cundy, Donald C; Falaleev, V; Fidecaro, Maria; Gatignon, L; Gonidec, A; Kubischta, Werner; Norton, A; Maier, A; Patel, M; Peters, A; Balev, S; Frabetti, P L; Goudzovski, E; Khristov, P Z; Kekelidze, V; Kozhuharov, V; Litov, L; Madigozhin, D T; Marinova, E; Molokanova, N; Polenkevich, I; Potrebenikov, Yu; Stoynev, S; Zinchenko, A; Monnier, E; Swallow, E; Winston, R; Rubin, P; Walker, A; Baldini, W; Cotta-Ramusino, A; Dalpiaz, P; Damiani, C; Fiorini, M; Gianoli, A; Martini, M; Petrucci, F; Savrié, M; Scarpa, M; Wahle, H; Bizzeti, A; Calvetti, M; Celeghini, E; Iacopini, E; Lenti, M; Martelli, F; Ruggiero, G; Veltri, M; Behler, M; Eppard, K; Kleinknecht, K; Marouelli, P; Masetti, L; Moosbrugger, U; Morales-Morales, C; Renk, B; Wache, M; Wanke, R; Winhart, A; Coward, D; Dabrowski, A; Fonseca-Martin, T; Shieh, M; Szleper, M; Velasco, M; Wood, M D; Anzivino, Giuseppina; Cenci, P; Imbergamo, E; Nappi, A; Pepé, M; Petrucci, M C; Piccini, M; Raggi, M; Valdata-Nappi, M; Cerri, C; Collazuol, G; Costantini, F; Di Lella, L; Doble, N; Fantechi, R; Fiorini, L; Giudici, S; Lamanna, G; Mannelli, I; Michetti, A; Pierazzini, G; Sozzi, M; Bloch-Devaux, B; Cheshkov, C; Chèze, J B; De Beer, M; Derré, J; Marel, Gérard; Mazzucato, E; Peyaud, B; Vallage, B; Holder, M; Ziolkowski, M; Bifani, S; Biino, C; Cartiglia, N; Clemencic, M; Goy-Lopez, S; Marchetto, F; Dibon, Heinz; Jeitler, Manfred; Markytan, Manfred; Mikulec, I; Neuhofer, G; Widhalm, L
2008-01-01
We report results from a new measurement of the K_{e4} decay K^{+-} -> \\pi^+ \\pi^- e^{+-} v by the NA48/2 collaboration at the CERN SPS, based on a partial sample of more than 670000 Ke4 decays in both charged modes collected in 2003. The form factors of the hadronic current (F, G, H) and pi pi scattering phase shift delta00-delta11 have been measured using a model-independent method and their variation with the pi pi mass has been investigated. Thanks to a sizeable acceptance at large pi pi mass, a low background and a very good resolution, an improved accuracy (+- 0.006 stat +- 0.002 syst), a factor two better than in the previous measurement, is reached when extracting the pi pi scattering length a00.
International Nuclear Information System (INIS)
Larsson, S.A.; Johansson, L.; Jonsson, C.; Pagani, M.; Jacobsson, H.
2000-01-01
A newly designed technique for experimental single-photon emission tomography (SPET) and positron emission tomography (PET) data acquisition with minor disturbing effects from scatter and attenuation has been developed. In principle, the method is based on discrete sampling of the radioactivity distribution in 3D objects by means of equidistant 2D planes. The starting point is a set of digitised 2D sections representing the radioactivity distribution of the 3D object. Having a radioactivity-related grey scale, the 2D images are printed on paper sheets using radioactive ink. The radioactive sheets can be shaped to the outline of the object and stacked into a 3D structure with air or some arbitrary dense material in between. For this work, equidistantly spaced transverse images of a uniform cylindrical phantom and of the digitised Hoffman rCBF phantom were selected and printed out on paper sheets. The uniform radioactivity sheets were imaged on the surface of a low-energy ultra-high-resolution collimator (4 mm full-width at half-maximum) of a three-headed SPET camera. The reproducibility was 0.7% and the uniformity was 1.2%. Each rCBF sheet, containing between 8.3 and 80 MBq of 99m TcO 4 - depending on size, was first imaged on the collimator and then stacked into a 3D structure with constant 12 mm air spacing between the slices. SPET was performed with the sheets perpendicular to the central axis of the camera. The total weight of the stacked rCBF phantom in air was 63 g, giving a scatter contribution comparable to that of a point source in air. The overall attenuation losses were <20%. A second SPET study was performed with 12-mm polystyrene plates in between the radioactive sheets. With polystyrene plates, the total phantom weight was 2300 g, giving a scatter and attenuation magnitude similar to that of a patient study. With the proposed technique, it is possible to obtain ''ideal'' experimental images (essentially built up by primary photons) for comparison with
Electric light scattering from single-stranded DNA in linear polyacrylamide solutions.
Todorov, R; Starchev, K; Stoylov, S P
2001-01-01
The electric light scattering (ELS) of ssDNA (calf thymus, 10 kbp, 55 micrograms/mL) in denaturing polyacrylamide (PAA) solutions was studied as a function of applied sinusoidal electric field and polymer concentration. Electric fields of strengths up to 300 V/cm and of frequencies between 100 and 5000 Hz were applied. It was found that the ELS effect increases with the field strength and decreases at high frequencies. The dependence of the ELS effect of ssDNA on polymer concentration passes through a maximum at 1% PAA. The relaxation times of decay of the ELS effect increase with increasing polymer concentrations. It was demonstrated that ELS is a useful method for investigation of ssDNA behavior in the course of pulse-field electrophoresis in polymer solutions.
A single-component liquid-phase hydrogen storage material.
Luo, Wei; Campbell, Patrick G; Zakharov, Lev N; Liu, Shih-Yuan
2011-12-07
The current state-of-the-art for hydrogen storage is compressed H(2) at 700 bar. The development of a liquid-phase hydrogen storage material has the potential to take advantage of the existing liquid-based distribution infrastructure. We describe a liquid-phase hydrogen storage material that is a liquid under ambient conditions (i.e., at 20 °C and 1 atm pressure), air- and moisture-stable, and recyclable; releases H(2) controllably and cleanly at temperatures below or at the proton exchange membrane fuel cell waste-heat temperature of 80 °C; utilizes catalysts that are cheap and abundant for H(2) desorption; features reasonable gravimetric and volumetric storage capacity; and does not undergo a phase change upon H(2) desorption. © 2011 American Chemical Society
Energy Technology Data Exchange (ETDEWEB)
., Nuruzzaman [Hampton Univ., Hampton, VA (United States)
2014-12-01
The Q-weak experiment in Hall-C at the Thomas Jefferson National Accelerator Facility has made the first direct measurement of the weak charge of the proton through the precision measurement of the parity-violating asymmetry in elastic electron-proton scattering at low momentum transfer. There is also a parity conserving Beam Normal Single Spin Asymmetry or transverse asymmetry (B_n) on H_2 with a sin(phi)-like dependence due to two-photon exchange. If the size of elastic B_n is a few ppm, then a few percent residual transverse polarization in the beam, combined with small broken azimuthal symmetries in the detector, would require a few ppb correction to the Q-weak data. As part of a program of B_n background studies, we made the first measurement of B_n in the N-to-Delta(1232) transition using the Q-weak apparatus. The final transverse asymmetry, corrected for backgrounds and beam polarization, was found to be B_n = 42.82 ± 2.45 (stat) ± 16.07 (sys) ppm at beam energy E_beam = 1.155 GeV, scattering angle theta = 8.3 deg, and missing mass W = 1.2 GeV. B_n from electron-nucleon scattering is a unique tool to study the gamma^* Delta Delta form factors, and this measurement will help to improve the theoretical models on beam normal single spin asymmetry and thereby our understanding of the doubly virtual Compton scattering process. To help correct false asymmetries from beam noise, a beam modulation system was implemented to induce small position, angle, and energy changes at the target to characterize detector response to the beam jitter. Two air-core dipoles separated by ~10 m were pulsed at a time to produce position and angle changes at the target, for virtually any tune of the beamline. The beam energy was modulated using an SRF cavity. The hardware and associated control instrumentation will be described in this dissertation. Preliminary detector sensitivities were extracted which helped to reduce the width of the measured asymmetry. The beam modulation system
International Nuclear Information System (INIS)
Lemonnier, H.; Hervieu, E.
1991-01-01
Phase separation in a tee-junction is modelled in the particular case of bubbly-flow. The model is based on a two-dimensional approach and hence, uses local equations. The first step consists in modelling the single-phase flow in the tee-junction. The free streamline theory is used to predict the flow of the continuous phase. The two recirculation zones which are presented in this case are predicted by the model. The second step consists in predicting the gas bubble paths as a result of the actions of the single-phase flow. Finally, the trajectories of gas bubbles are used to predict the separation characteristics of the tee-junction. Each step of the modelling procedure has been carefully tested by an in-depth experimental investigation. Excellent quantitative agreement is obtained between experimental results and model predictions. Moreover, the phase separation phenomenon is found to be clearly described by the model. (orig.)
DEFF Research Database (Denmark)
Golestan, Saeed; Guerrero, Josep M.; Abusorrah, Abdullah
2017-01-01
The quadrature signal generation based phase-locked loops (QSG-PLLs) are highly popular for synchronization purposes in single-phase systems. The main difference among these PLLs often lies in the technique they use for creating the fictitious quadrature component. One of the easiest QSG approaches...... is delaying the original single-phase signal by a quarter of a cycle. The PLL with such QSG technique is often called the transfer delay based PLL (TD-PLL). The TD-PLL benefits from a simple structure, rather fast dynamic response, and a good detection accuracy when the grid frequency is at its nominal value......, but it suffers from a phase offset error and double frequency oscillatory error in the estimated phase and frequency in the presence of frequency drifts. In this paper, a simple yet effective approach to remove the aforementioned errors of the TD-PLL is proposed. The resultant PLL structure is called...
DNA Origami Directed Au Nanostar Dimers for Single-Molecule Surface-Enhanced Raman Scattering.
Tanwar, Swati; Haldar, Krishna Kanta; Sen, Tapasi
2017-12-06
We demonstrate the synthesis of Au nanostar dimers with tunable interparticle gap and controlled stoichiometry assembled on DNA origami. Au nanostars with uniform and sharp tips were immobilized on rectangular DNA origami dimerized structures to create nanoantennas containing monomeric and dimeric Au nanostars. Single Texas red (TR) dye was specifically attached in the junction of the dimerized origami to act as a Raman reporter molecule. The SERS enhancement factors of single TR dye molecules located in the conjunction region in dimer structures having interparticle gaps of 7 and 13 nm are 2 × 10 10 and 8 × 10 9 , respectively, which are strong enough for single analyte detection. The highly enhanced electromagnetic field generated by the plasmon coupling between sharp tips and cores of two Au nanostars in the wide conjunction region allows the accommodation and specific detection of large biomolecules. Such DNA-directed assembled nanoantennas with controlled interparticle separation distance and stoichiometry, and well-defined geometry, can be used as excellent substrates in single-molecule SERS spectroscopy and will have potential applications as a reproducible platform in single-molecule sensing.
An Asymmetrical Space Vector Method for Single Phase Induction Motor
DEFF Research Database (Denmark)
Cui, Yuanhai; Blaabjerg, Frede; Andersen, Gert Karmisholt
2002-01-01
the motor torque performance is not good enough. This paper addresses a new control method, an asymmetrical space vector method with PWM modulation, also a three-phase inverter is used for the main winding and the auxiliary winding. This method with PWM modulation is implemented to control the motor speed...
Single-layer dual germanene phases on Ag(111)
Lin, Chung-Huang; Huang, Angus; Pai, Woei Wu; Chen, Wei-Chuan; Chen, Ting-Yu; Chang, Tay-Rong; Yukawa, Ryu; Cheng, Cheng-Maw; Mou, Chung-Yu; Matsuda, Iwao; Chiang, T.-C.; Jeng, H.-T.; Tang, S.-J.
2018-02-01
Two-dimensional (2D) honeycomb lattices beyond graphene promise new physical properties such as quantum spin Hall effect. While there have been claims of growth of such lattices (silicene, germanene, stanene), their existence needs further support and their preparation and characterization remain a difficult challenge. Our findings suggest that two distinct phases associated with germanene, the analog of graphene made of germanium (Ge) instead of carbon, can be grown on Ag(111) as observed by scanning tunneling microscopy, low-energy electron diffraction, and angle-resolved photoemission spectroscopy. One such germanene exhibits an atom-resolved alternatively buckled full honeycomb lattice, which is tensile strained and partially commensurate with the substrate to form a striped phase (SP). The other, a quasifreestanding phase (QP), is also consistent with a honeycomb lattice with a lattice constant incommensurate with the substrate but very close to the theoretical value for freestanding germanene. The SP, with a lower atomic density, can be driven into the QP and coexist with the QP by additional Ge deposition. Band mapping and first-principles calculations with proposed SP and QP models reveal an interface state exists only in the SP but the characteristic σ band of freestanding germanene emerges only in the QP—this leads to an important conclusion that adlayer-substrate commensurability plays a key role to affect the electronic structure of germanene. The evolution of the dual germanene phases manifests the competitive formation of Ge-Ge covalent and Ge-Ag interfacial bonds.
A single phase photovoltaic inverter control for grid connected system
Indian Academy of Sciences (India)
during light load condition the excess energy generated from the PV inverter is fed to the grid and; during an overload condition or in case of unfavorable atmospheric conditions the load demand is met by both PV inverter and the grid. In order to synchronize the PV inverter with the grid a dual transport delay based phase ...
Muñoz, O.; Hovenier, J.W.
2011-01-01
In this paper we present an overview of light scattering experiments devoted to measure one or more elements of the scattering matrix as functions of the scattering angle of ensembles of randomly oriented small irregular particles in air. A summary of the most important findings in light scattering
A single phase photovoltaic inverter control for grid connected system
Indian Academy of Sciences (India)
Melo G and Canesin C A 2013 Evaluation of the main MPPT techniques for photovoltaic applications. IEEE Trans. Ind. Electron. 60(3): 1156–1167. [7] Jain S and Agarwal V 2007 Comparison of the perfor- mance of maximum power point tracking schemes applied to single-stage grid-connected photovoltaic systems.
Tsuruta, H.; Yabuki, M.; Takamura, T.; Sudo, S.; Yonemura, S.; Shirasuna, Y.; Hirano, K.; Sera, K.; Maeda, T.; Hayasaka, T.; Nakajima, T.
2008-12-01
An intensive field program was performed to measure atmospheric aerosols at Amami-Oshima, a small island located at southwest Japan, in the spring season of 2001, 2003, and 2005 under the ACE-Asia, APEX and ABC-EAREX2005 projects. Chemical analysis of the fine and coarse aerosols was made for elemental carbon (EC) and organic carbon, water soluble ions, and trace elements. Single scattering albedo (SSA) of aerosols was independently estimated by two methods. The one (SSAc) is by chemical compositions assuming a half internal mixture between EC and non sea-salt sulfate, and the other (SSAo) is by optical measurements of scattering coefficient and absorption coefficient. The backward trajectory analysis showed that the aerosol concentrations in the air masses arrived at Amami, were much higher from the Asian Continent than from other regions, and two types of aerosol enhancement were observed. The one was caused by polluted air masses from the urban-industrial area of east-coast China, the other was by high mineral dusts due to large- scale dust storms in the desert regions of northwest China. The SSAc was in a range of 0.87-0.98, and in good agreement with the SSAo after some corrections for original scattering and absorption coefficients. The SSAc showed no significant difference between the air masses from the polluted area and the desert regions. The negative correlation between the SSAc and EC was divided into two groups depending on the concentration of non sea-salt sulfate, while the increase in mineral dusts did not show any correlation with the SSAc.
Magnani, N; Caciuffo, R; Lander, G H; Hiess, A; Regnault, L-P
2010-03-24
The anisotropy of magnetic fluctuations propagating along the [1 1 0] direction in the ordered phase of uranium antimonide has been studied using polarized inelastic neutron scattering. The observed polarization behavior of the spin waves is a natural consequence of the longitudinal 3-k magnetic structure; together with recent results on the 3-k-transverse uranium dioxide, these findings establish this technique as an important tool to study complex magnetic arrangements. Selected details of the magnon excitation spectra of USb have also been reinvestigated, indicating the need to revise the currently accepted theoretical picture for this material.
Marrone, Salvatore; Colagrossi, Andrea; Di Mascio, Andrea; Le Touzé, David
2016-05-01
The study of energetic free-surface flows is challenging because of the large range of interface scales involved due to multiple fragmentations and reconnections of the air-water interface with the formation of drops and bubbles. Because of their complexity the investigation of such phenomena through numerical simulation largely increased during recent years. Actually, in the last decades different numerical models have been developed to study these flows, especially in the context of particle methods. In the latter a single-phase approximation is usually adopted to reduce the computational costs and the model complexity. While it is well known that the role of air largely affects the local flow evolution, it is still not clear whether this single-phase approximation is able to predict global flow features like the evolution of the global mechanical energy dissipation. The present work is dedicated to this topic through the study of a selected problem simulated with both single-phase and two-phase models. It is shown that, interestingly, even though flow evolutions are different, energy evolutions can be similar when including or not the presence of air. This is remarkable since, in the problem considered, with the two-phase model about half of the energy is lost in the air phase while in the one-phase model the energy is mainly dissipated by cavity collapses.
Koo, Ja-Ho; Kim, Jhoon; Lee, Jaehwa; Eck, Thomas F.; Lee, Yun Gon; Park, Sang Seo; Kim, Mijin; Jung, Ukkyo; Yoon, Jongmin; Mok, Jungbin; Cho, Hi-Ku
2016-11-01
Absorption and scattering characteristics of various aerosol events are investigated using 2-years of measurements from a skyradiometer at Yonsei University in Seoul, Korea. Both transported dust and anthropogenic aerosols are observed at distinct geo-location of Seoul, a megacity located a few thousand kilometers away from dust source regions in China. We focus on the wavelength dependence of Ångström exponent (AE) and single scattering albedo (SSA), showing the characteristics of regional aerosols. The correlation between spectral SSAs and AEs calculated using different wavelength pairs generally indicates relatively weak absorption of fine-mode aerosols (urban pollution and/or biomass burning) and strong absorption of coarse-mode aerosols (desert dust) at this location. AE ratio (AER), a ratio of AEs calculated using wavelength pair between shorter (340-675 nm) and longer wavelength pair (675-1020 nm) correlates differently with SSA according to the dominant size of local aerosols. Correlations between SSA and AER show strong absorption of aerosols for AER 2.0. Based on the seasonal pattern of wavelength dependence of AER and SSA, this correlation difference looks to reveal the separated characteristics of transported dust and anthropogenic particles from urban pollution respectively. The seasonal characteristics of AER and SSAs also show that the skyradiometer measurement with multiple wavelengths may be able to detect the water soluble brown carbon, one of the important secondary organic aerosols in the summertime atmospheric composition.
Numerical Simulations of Single and Multiple Scattering by Fractal Ice Clusters
Dlugach, Janna M.; Mishchenko, Michael I.; Mackowski, Daniel W.
2011-01-01
We consider the scattering model in the form of a vertically and horizontally homogeneous particulate slab of an arbitrary optical thickness composed of widely separated fractal aggregates built of small spherical ice monomers. The aggregates are generated by applying three different approaches, including simulated cluster-cluster aggregation (CCA) and diffusion-limited aggregation (DLA) procedures. Having in mind radar remote-sensing applications, we report and analyze the results of computations of the backscattering circular polarization ratio obtained using efficient superposition T-matrix and vector radiative-transfer codes. The computations have been performed at a wavelength of 12.6 cm for fractal aggregates with the following characteristics: monomer refractive index m=1.78+i0.003, monomer radius r=1 cm, monomer packing density p=0.2, overall aggregate radii R in the range 4fractal dimensions D(sub f) 2.5 and 3. We show that for aggregates generated with simulated CCA and DLA procedures, the respective values of the backscattering circular polarization ratio differ weakly for D(sub f) 2.5, but the differences can increase somewhat for D(sub f)3, especially in case of an optically semi-infinite medium. For aggregates with a spheroidal overall shape, the dependence of the circular polarization ratio on the cluster morphology can be quite significant and increases with increasing the aspect ratio of the circumscribing spheroid.
Single-arm phase II trial design under parametric cure models.
Wu, Jianrong
2015-01-01
The current practice of designing single-arm phase II survival trials is limited under the exponential model. Trial design under the exponential model may not be appropriate when a portion of patients are cured. There is no literature available for designing single-arm phase II trials under the parametric cure model. In this paper, a test statistic is proposed, and a sample size formula is derived for designing single-arm phase II trials under a class of parametric cure models. Extensive simulations showed that the proposed test and sample size formula perform very well under different scenarios. Copyright © 2015 John Wiley & Sons, Ltd.
Ohwada, Kenji; Hirota, Kazuma; Rehrig, Paul W.; Gehring, Peter M.; Noheda, Beatriz; Fujii, Yasuhiko; Park, Seung-Eek Eagle; Shirane, Gen
2001-01-01
Single crystals of the relaxor PZN-xPT display an enormously strong piezoelectric character. Recent x-ray scattering studies have revealed novel electric-field induced phase transitions in PZN-8%PT. As-grown crystals exhibit a rhombohedral structure that, under application of an electric field
Directory of Open Access Journals (Sweden)
Kazuo Uchida
2012-12-01
Full Text Available High-quality single crystalline twin phase NiO grown on sapphire substrates by metalorganic vapor phase epitaxy is reported. X-ray rocking curve analysis of NiO films grown at different temperatures indicates a minimum full width at half maximum of the cubic (111 diffraction peak of 0.107° for NiO film grown at as low as 550 °C. Detailed microstructural analysis by Φ scan X-ray diffraction and transmission electron microscopy reveal that the NiO film consists of large single crystalline domains with two different crystallographic orientations which are rotated relative to each other along the [111] axis by 60°. These single crystal domains are divided by the twin phase boundaries.
International Nuclear Information System (INIS)
Constantinescu, L.M.
1994-01-01
Small-angle neutron scattering has been used in the study of chain conformation of lamellar styrene/isoprene block copolymers oriented in large single crystals. The radius of gyration of deuterated polystyrene chains around the normal to the interface has been measured. By comparing this direct evolution of the lateral dimension of the chains with the average chain separation given by the molecular area (the surface available at the interface for each covalent bond linking the blocks together) we characterized the transverse interpenetration degree of the chains. The polystyrene chains are displayed in simple strata own micro-domains, without an important interpenetration. (Author) 9 Figs., 2 Tabs., 25 Refs
Single-shot femtosecond-pulsed phase-shifting digital holography.
Kakue, Takashi; Itoh, Seiya; Xia, Peng; Tahara, Tatsuki; Awatsuji, Yasuhiro; Nishio, Kenzo; Ura, Shogo; Kubota, Toshihiro; Matoba, Osamu
2012-08-27
Parallel phase-shifting digital holography is capable of three-dimensional measurement of a dynamically moving object with a single-shot recording. In this letter, we demonstrated a parallel phase-shifting digital holography using a single femtosecond light pulse whose central wavelength and temporal duration were 800 nm and 96 fs, respectively. As an object, we set spark discharge in atmospheric pressure air induced by applying a high voltage to between two electrodes. The instantaneous change in phase caused by the spark discharge was clearly reconstructed. The reconstructed phase image shows the change of refractive index of air was -3.7 × 10(-4).
Asadi, Reza; Ouyang, Zhengbiao
2018-03-01
A new mechanism for out-of-plane coupling into a waveguide is presented and numerically studied based on nonlinear scattering of a single nano-scale Graphene layer inside the waveguide. In this mechanism, the refractive index nonlinearity of Graphene and nonhomogeneous light intensity distribution occurred due to the interference between the out-of-plane incident pump light and the waveguide mode provide a virtual grating inside the waveguide, coupling the out-of-plane pump light into the waveguide. It has been shown that the coupling efficiency has two distinct values with high contrast around a threshold pump intensity, providing suitable condition for digital optical applications. The structure operates at a resonance mode due to band edge effect, which enhances the nonlinearity and decreases the required threshold intensity.
Kitt, Jay P; Harris, Joel M
2014-02-04
Solid-phase extraction (SPE) is a well-known method for separating and preconcentrating analytes prior to ex situ detection and quantification. Despite advances in the miniaturization of solid-phase extraction, the technique has not evolved to meet the needs for detection in small-scale microfluidic devices. Although successful efforts have led to smaller-scale extractors that allow preconcentration from small volumes, detection within correspondingly small volumes has remained out of reach because of analyte dilution during a postextraction transfer or "wash-off" step prior to detection. In this work, successful extraction into subpicoliter collection volumes is accomplished by using a single chromatographic particle as an extractor; wash-off dilution is completely avoided by using confocal Raman microscopy for in situ detection within the single-particle collection phase. Specifically, micromolar concentrations of pyrene in methanol/water solution were equilibrated with an individual C18-functionalized silica particle, and Raman spectra were acquired from a small confocal sampling volume (∼1 fL) within the particle interior. By comparing the Raman scattering intensity of the pyrene with that of the C18 chains in the stationary phase, it was possible to quantify the equilibrium coverage of pyrene relative to the C18 chains. Spectroscopic isotherms were measured to determine the saturation surface coverage of pyrene relative to C18 chains and to study how the preconcentration equilibrium can be controlled by the source-phase solution composition. For extraction from aqueous solutions having the lowest methanol concentration (5% by volume), the preconcentration factor for pyrene into the particle was found to be 4.8 (±0.8) × 10(4), which allowed detection of pyrene extracted from a 10 nM solution into a 0.52-pL particle volume.
Diffuse neutron scattering of interesting phases in Dy2Ti2O7
Energy Technology Data Exchange (ETDEWEB)
Morris, Jonathan; Rule, Kirrily; Klemke, Bastian [Helmholtz-Zentrum Berlin for Materials and Energy, Berlin (Germany); Tennant, Alan [Helmholtz-Zentrum Berlin for Materials and Energy, Berlin (Germany); Institut fur Festkoerperphysik, Technische Universitaet Berlin (Germany); Grigera, Santiago [St. Andrew' s University, St. Andrews (United Kingdom); Instituto de Fisica de Liquidos y Sistemas Biologicos, La Plata (Argentina)
2009-07-01
The prospect of observing emergent magnetic monopoles in spin-ice has recently increased the interest in these systems. Dy{sub 2}Ti{sub 2}O{sub 7} is a effective spin-1/2 pyrochlore which is a clean model frustrated system where interesting physics may be observed and compared with theory. Here we present new neutron measurements from E2 at the Helmholtz-Zentrum Berlin which show an agreement with spin-ice correlation functions at 0.7 K and 0 T, and a complex Q-dependent diffuse scattering at fields below the saturation field along[100]. These are being understood in the context of spin-strings, or spin-random-walks, which are the prerequisite for monopoles. The scattering allows us to follow the development of these strings with field and provides new insight into the Kastelyn physics within this pyrochlore.
The surface phase diagram of Li/Cu(001) explored by helium atom scattering
Energy Technology Data Exchange (ETDEWEB)
Huang Congcong; MacLaren, D A; Bacon, R T; Allison, W, E-mail: congcong@slac.stanford.edu [Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge CB3 0HE (United Kingdom)
2011-09-07
We use helium atom scattering to investigate the structures formed by Li adsorption onto Cu(001) in the 0-2 ML regime. Submonolayer growth at 180 K proceeds through a sequence of ordered overlayers, including a c(2 x 2) structure at 0.5 ML and a series of 'ladder' superlattices around 0.6 ML. Beyond 1 ML, incommensurate, three-dimensional Li islands develop. A quantum close-coupled scattering analysis is performed to study the empirical He-surface potential of the structurally heterogeneous ladder structures. Good agreement with the measured distribution of diffracted intensity is obtained by describing the He-ladder interaction potential as the summation of only six one-dimensional Fourier components. The fitted potential indicates a remarkably flat surface that is punctuated by substantial, striped protrusions in the electron density. The result is consistent with the formation of one-dimensional Li wires, indicating an inhomogeneous metallization process.
Surface-enhanced Raman scattering from a single molecularly bridged silver nanoparticle aggregate
Czech Academy of Sciences Publication Activity Database
Sládková, M.; Vlčková, B.; Pavel, I.; Šišková, Karolína; Šlouf, Miroslav
924-26, SI (2009), s. 567-570 ISSN 0022-2860. [European Congress on Molecular Spectroscopy /29./. Opatija, 31.08.2008-05.09.2008] R&D Projects: GA ČR GA203/07/0717; GA AV ČR KAN100500652 Institutional research plan: CEZ:AV0Z40500505 Keywords : single molecule SERS * 4,4"-diaminoterphenyl * molecularly bridget Ag nanoparticle aggregates Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.551, year: 2009
Single view reflectance capture using multiplexed scattering and time-of-flight imaging
Zhao, Shuang; Velten, Andreas; Raskar, Ramesh; Bala, Kavita; Naik, Nikhil Deepak
2011-01-01
This paper introduces the concept of time-of-flight reflectance estimation, and demonstrates a new technique that allows a camera to rapidly acquire reflectance properties of objects from a single view-point, over relatively long distances and without encircling equipment. We measure material properties by indirectly illuminating an object by a laser source, and observing its reflected light indirectly using a time-of-flight camera. The configuration collectively acquires dense angular, but l...
Alignment characterization of single-wall carbon nanotubes by Raman scattering
International Nuclear Information System (INIS)
Liu Pijun; Liu Liyue; Zhang Yafei
2003-01-01
A novel method for identifying the Raman modes of single-wall carbon nanotubes (SWNT) based on the symmetry of the vibration modes has been studied. The Raman intensity of each vibration mode varies with polarization direction, and the relationship can be expressed as analytical functions. This method avoids troublesome numerical calculation and easily gives clear relations between Raman intensity and polarization direction. In this way, one can distinguish each Raman-active mode of SWNT through the polarized Raman spectrum
Single-Phase Direct Boost AC-AC Converter
Directory of Open Access Journals (Sweden)
URSARU, O.
2017-11-01
Full Text Available This paper introduces and studies a boost AC-AC converter circuit that can be used to supply power to the 220V receivers in the 110V grids or to increase and adjust voltage at the end of long lines. High frequency AC-AC converters have better specifications than alternative voltage phase control drives with thyristors or TRIACs. When frequency exceeds 20kHz, noise is eliminated, filters are smaller and efficiency is higher. The current waveform is much better, the output voltage can be higher than the input voltage and voltage control is more accurate.
In situ neutron scattering study of nanoscale phase evolution in PbTe-PbS thermoelectric material
Energy Technology Data Exchange (ETDEWEB)
Ren, Fei, E-mail: renfei@temple.edu, E-mail: kean@ornl.gov; Qian, Bosen [Department of Mechanical Engineering, Temple University, Philadelphia, Pennsylvania 19122 (United States); Schmidt, Robert; Case, Eldon D. [Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, Michigan 48824 (United States); Keum, Jong K.; Littrell, Ken C.; An, Ke, E-mail: renfei@temple.edu, E-mail: kean@ornl.gov [Chemical and Engineering Materials Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830 (United States)
2016-08-22
Introducing nanostructural second phases has proved to be an effective approach to reduce the lattice thermal conductivity and thus enhances the figure of merit for many thermoelectric materials. Studies of the formation and evolution of these second phases are essential to understanding material temperature dependent behaviors, improving thermal stabilities, as well as designing new materials. In this study, powder samples of the PbTe-PbS thermoelectric material were examined using in situ neutron diffraction and small angle neutron scattering (SANS) techniques between room temperature and elevated temperature up to 663 K, to explore quantitative information on the structure, weight fraction, and size of the second phase. Neutron diffraction data showed that the as-milled powder was primarily a solid solution prior to heat treatment. During heating, a PbS second phase precipitated out of the PbTe matrix around 500 K, while re-dissolution started around 600 K. The second phase remained separated from the matrix upon cooling. Furthermore, SANS data indicated that there are two populations of nanostructures. The size of the smaller nanostructure increased from initially 5 nm to approximately 25 nm after annealing at 650 K, while the size of the larger one remained unchanged. This study demonstrated that in situ neutron techniques are effective means to obtain quantitative information on temperature-dependent nanostructural behavior of thermoelectrics and likely other high-temperature materials.
In situ neutron scattering study of nanoscale phase evolution in PbTe-PbS thermoelectric material
Ren, Fei; Schmidt, Robert; Keum, Jong K.; Qian, Bosen; Case, Eldon D.; Littrell, Ken C.; An, Ke
2016-08-01
Introducing nanostructural second phases has proved to be an effective approach to reduce the lattice thermal conductivity and thus enhances the figure of merit for many thermoelectric materials. Studies of the formation and evolution of these second phases are essential to understanding material temperature dependent behaviors, improving thermal stabilities, as well as designing new materials. In this study, powder samples of the PbTe-PbS thermoelectric material were examined using in situ neutron diffraction and small angle neutron scattering (SANS) techniques between room temperature and elevated temperature up to 663 K, to explore quantitative information on the structure, weight fraction, and size of the second phase. Neutron diffraction data showed that the as-milled powder was primarily a solid solution prior to heat treatment. During heating, a PbS second phase precipitated out of the PbTe matrix around 500 K, while re-dissolution started around 600 K. The second phase remained separated from the matrix upon cooling. Furthermore, SANS data indicated that there are two populations of nanostructures. The size of the smaller nanostructure increased from initially 5 nm to approximately 25 nm after annealing at 650 K, while the size of the larger one remained unchanged. This study demonstrated that in situ neutron techniques are effective means to obtain quantitative information on temperature-dependent nanostructural behavior of thermoelectrics and likely other high-temperature materials.
In situ neutron scattering study of nanoscale phase evolution in PbTe-PbS thermoelectric material
International Nuclear Information System (INIS)
Ren, Fei; Qian, Bosen; Schmidt, Robert; Case, Eldon D.; Keum, Jong K.; Littrell, Ken C.; An, Ke
2016-01-01
Introducing nanostructural second phases has proved to be an effective approach to reduce the lattice thermal conductivity and thus enhances the figure of merit for many thermoelectric materials. Studies of the formation and evolution of these second phases are essential to understanding material temperature dependent behaviors, improving thermal stabilities, as well as designing new materials. In this study, powder samples of the PbTe-PbS thermoelectric material were examined using in situ neutron diffraction and small angle neutron scattering (SANS) techniques between room temperature and elevated temperature up to 663 K, to explore quantitative information on the structure, weight fraction, and size of the second phase. Neutron diffraction data showed that the as-milled powder was primarily a solid solution prior to heat treatment. During heating, a PbS second phase precipitated out of the PbTe matrix around 500 K, while re-dissolution started around 600 K. The second phase remained separated from the matrix upon cooling. Furthermore, SANS data indicated that there are two populations of nanostructures. The size of the smaller nanostructure increased from initially 5 nm to approximately 25 nm after annealing at 650 K, while the size of the larger one remained unchanged. This study demonstrated that in situ neutron techniques are effective means to obtain quantitative information on temperature-dependent nanostructural behavior of thermoelectrics and likely other high-temperature materials.
A Novel Model Predictive Control for Single-Phase Grid-Connected Photovoltaic Inverters
DEFF Research Database (Denmark)
Zangeneh Bighash, Esmaeil; Sadeghzadeh, Seyed Mohammad; Ebrahimzadeh, Esmaeil
2017-01-01
Single-phase grid-connected inverters with LCL filter are widely used to connect photovoltaic systems to the utility grid. Among the existing control schemes, predictive control methods are faster and more accurate but also more complicated to implement. Recently, the Model Predictive Control (MPC......) algorithm for single-phase inverter has been presented, where the algorithm implementation is straightforward. In the MPC approach, all switching states are considered in each switching period to achieve the control objectives. However, since the number of switching states in single-phase inverters is small...... vectors. Simulation results show that the proposed approach lead to a lower THD in the injected current combined with fast dynamics. The proposed predictive control has been simulated and implemented on a 1 kW single-phase HERIC (highly efficient and reliable inverter concept) inverter with an LCL filter...
High Energy Single Frequency Fiber Laser at Low Repetition Rate, Phase I
National Aeronautics and Space Administration — This SBIR phase I project proposes a tunable single frequency high energy fiber laser system for coherent Lidar systems for remote sensing. Current state-of-art...
Tunable High-Power Single-Frequency Laser at 2050 nm, Phase I
National Aeronautics and Space Administration — We propose a novel new architecture for a low-phase noise electronically tunable laser single-frequency laser at 2.05 microns that meets all the demanding...
High Energy Single Frequency Fiber Laser at Low Repetition Rate, Phase II
National Aeronautics and Space Administration — This SBIR phase II project proposes a single frequency high energy fiber laser system operating at low repetition rate of 10 Hz to 1 kHz for coherent Lidar systems...
Pulsed, Single-Frequency, 2-um Seed Source for Coherent LIDAR Applications, Phase I
National Aeronautics and Space Administration — The primary objective of the proposed Phase I effort is to develop and demonstrate a low-average power, pulsed, single-frequency, 2-um Ho-laser source for...
Light-Weight, Low-Cost, Single-Phase, Liquid-Cooled Cold Plate (Presentation)
Energy Technology Data Exchange (ETDEWEB)
Narumanchi, S.
2013-07-01
This presentation, 'Light-Weight, Low-Cost, Single-Phase Liquid-Cooled Cold Plate,' directly addresses program goals of increased power density, specific power, and lower cost of power electronics components through improved thermal management.
A High Energy and High Efficiency Spectral Shaping Single Frequency Fiber Laser, Phase II
National Aeronautics and Space Administration — This SBIR phase II project proposes a single frequency high energy fiber laser system for coherent Lidar systems for remote sensing. Current state-of-art...
American Society for Testing and Materials. Philadelphia
1983-01-01
1.1 This specification covers the basic requirements for equipment to be used for the collection of uncontaminated and representative samples from single-phase geothermal liquid or steam. Geopressured liquids are included. See Fig 1.
A High Energy and High Efficiency Spectral Shaping Single Frequency Fiber Laser, Phase I
National Aeronautics and Space Administration — This SBIR phase I project proposes a tunable single frequency high energy fiber laser system for coherent Lidar systems for remote sensing. Current state-of-art...
High Power Compact Single-Frequency Volume Bragg Er-Doped Fiber Laser, Phase I
National Aeronautics and Space Administration — The purpose of this NASA SBIR Phase I proposal is to develop the prototype of a compact single-frequency mode one longitudinal and one transverse mode laser...
Evidence of low intermolecular coupling in rubrene single crystals by Raman scattering
International Nuclear Information System (INIS)
Weinberg-Wolf, J R; McNeil, L E; Liu Shubin; Kloc, Christian
2007-01-01
The observed Raman spectra for single crystals of rubrene and tetracene are compared with the calculated spectra for the isolated molecules. The Raman measurements presented are of the bulk properties of the material, and they confirmed that the vapour growth process yields very pure, unstrained rubrene crystals. Finally, Raman measurements indicate that rubrene, unlike many other oligoacenes, has very weak intermolecular coupling and no observable intermolecular Raman vibrational modes. We discuss the apparent conflict between the high mobility and the weak π-electron overlap in this material
Neutron scattering investigation of the magnetic order in single crystalline BaFe2As2
Kofu, M.; Qiu, Y.; Bao, Wei; Lee, S. -H.; Chang, S.; Wu, T.; Wu, G.; Chen, X. H.
2009-01-01
The magnetic structure of BaFe2As2 was completely determined from polycrystalline neutron diffraction measurements soon after the ThCr2Si2-type FeAs-based superconductors were discovered. Both the moment direction and the in-plane antiferromagnetic wavevector are along the longer a-axis of the orthorhombic unit cell. There is only one combined magnetostructural transition at about 140 K. However, a later single-crystal neutron diffraction work reported contradicting results. Here we show neut...
Hashemi, Roohollah
2017-03-01
In this paper, a robust methodology with several desirable features is developed for the determination of the magneto-electro-elastic fields of a shear (SH) wave scattered by a two-phase multiferroic fiber embedded in an infinite transversely isotropic piezoelectric or piezomagnetic medium. While the traditional wave-function expansion approach commonly used in the literature ceases to hold when the geometry of the obstacle is not symmetric, the present theory is capable of treating eccentric coating-fiber ensemble. To put its wide range of applicability in perspective, my analytical methodology is applied to several descriptive examples with various degrees of complexity. The calculated results reveals the profound influence of material properties of constituent phases, the thickness and eccentricity of coating layer, as well as the frequency of propagating SH-wave on the pertinent scattered fields induced by the multiferroic fiber. It is expected that the formulation and numerical results of this paper serve as a useful reference for the design and manufacture of multiferroic materials with a durable and yet reliable performance under dynamics loadings.
Direct single to two/three phase power electronic conversion for AC traction applications
Energy Technology Data Exchange (ETDEWEB)
Dobrucky, B.; Pavlanin, R.; Pokorny, M. [Zilina Univ. (Slovakia). Faculty of Electrical Engineering
2008-07-01
This paper discussed single to 3-phase power electronic converters. Conversion rates were evaluated using a middle frequency transformer with matrix converters. The use of a matrix converter subsystem with a 2-phase orthogonal induction motor was compared with conventional drives as a means of reducing the number of converter power switching elements. The converter was a high voltage modular multilevel converter where the transformer was fed directly by the single phase converter system operating on an AC line voltage. The converter offered sinusoidal input and output harmonics, eliminated the need for a DC link circuit, and decreased the number of switching elements for converters in AC-AC drives. A power active filter was used to improve the harmonic content of the input and output currents. Simulations of the 2-phase matrix converter orthogonal driving concept indicated that the converter can be used to provide solutions for single phase electric traction applications. 21 refs., 15 figs.
Coordinated single-phase control scheme for voltage unbalance reduction in low voltage network.
Pullaguram, Deepak; Mishra, Sukumar; Senroy, Nilanjan
2017-08-13
Low voltage (LV) distribution systems are typically unbalanced in nature due to unbalanced loading and unsymmetrical line configuration. This situation is further aggravated by single-phase power injections. A coordinated control scheme is proposed for single-phase sources, to reduce voltage unbalance. A consensus-based coordination is achieved using a multi-agent system, where each agent estimates the averaged global voltage and current magnitudes of individual phases in the LV network. These estimated values are used to modify the reference power of individual single-phase sources, to ensure system-wide balanced voltages and proper power sharing among sources connected to the same phase. Further, the high X / R ratio of the filter, used in the inverter of the single-phase source, enables control of reactive power, to minimize voltage unbalance locally. The proposed scheme is validated by simulating a LV distribution network with multiple single-phase sources subjected to various perturbations.This article is part of the themed issue 'Energy management: flexibility, risk and optimization'. © 2017 The Author(s).
Searching for Next Single-Phase High-Entropy Alloy Compositions
Directory of Open Access Journals (Sweden)
David E. Alman
2013-10-01
Full Text Available There has been considerable technological interest in high-entropy alloys (HEAs since the initial publications on the topic appeared in 2004. However, only several of the alloys investigated are truly single-phase solid solution compositions. These include the FCC alloys CoCrFeNi and CoCrFeMnNi based on 3d transition metals elements and BCC alloys NbMoTaW, NbMoTaVW, and HfNbTaTiZr based on refractory metals. The search for new single-phase HEAs compositions has been hindered by a lack of an effective scientific strategy for alloy design. This report shows that the chemical interactions and atomic diffusivities predicted from ab initio molecular dynamics simulations which are closely related to primary crystallization during solidification can be used to assist in identifying single phase high-entropy solid solution compositions. Further, combining these simulations with phase diagram calculations via the CALPHAD method and inspection of existing phase diagrams is an effective strategy to accelerate the discovery of new single-phase HEAs. This methodology was used to predict new single-phase HEA compositions. These are FCC alloys comprised of CoFeMnNi, CuNiPdPt and CuNiPdPtRh, and HCP alloys of CoOsReRu.
International Nuclear Information System (INIS)
Daimaru, Shuji; Takeuchi, Ryuji; Onoe, Hironori; Saegusa, Hiromitsu
2012-09-01
This report summarize the results of the single borehole hydraulic tests of 79 sections conducted as part of the Construction phase (Phase 2) in the Mizunami Underground Research Laboratory (MIU) Project. The details of each test (test interval depth, geology, etc.) as well as the interpreted hydraulic parameters and analytical method used are presented in this report. (author)
Synchronization in single-phase grid-connected photovoltaic systems under grid faults
DEFF Research Database (Denmark)
Yang, Yongheng; Blaabjerg, Frede
2012-01-01
under grid faults. The focus of this paper is put on the benchmarking of synchronization techniques, mainly about phase locked loop (PLL) based methods, in single-phase PV power systems operating under grid faults. Some faulty mode cases are studied at the end of this paper in order to compare...
Weimer, D.; Howes, W. L.
1984-01-01
Barium titanate single crystals are discussed in the context of: the procedure for polarizing a crystal; a test for phase conjugation; transients in the production of phase conjugation; real time readout by a separate laser of a hologram induced within the crystal, including conjugation response times to on-off switching of each beam; and a demonstration of a Twyman-Green interferometer utilizing phase conjugation.
A review of single-phase grid-connected inverters for photovoltaic modules
DEFF Research Database (Denmark)
Kjaer, Soren Baekhoej; Pedersen, John Kim; Blaabjerg, Frede
2005-01-01
This review focuses on inverter technologies for connecting photovoltaic (PV) modules to a single-phase grid. The inverters are categorized into four classifications: 1) the number of power processing stages in cascade; 2) the type of power decoupling between the PV module(s) and the single...
A Direct Maximum Power Point Tracking Method for Single-Phase Grid Connected PV Inverters
DEFF Research Database (Denmark)
EL Aamri, Faicel; Maker, Hattab; Sera, Dezso
2018-01-01
in dynamic conditions, especially in low irradiance when the measurement of signals becomes more sensitive to noise. The proposed MPPT is designed for single-phase single-stage grid-connected PV inverters, and is based on estimating the instantaneous PV power and voltage ripples, using second...
International Nuclear Information System (INIS)
TANNENBAUM, M.J.
2005-01-01
Hard scattering in p-p collisions, discovered at the CERN ISR in 1972 by the method of leading particles, proved that the partons of Deeply Inelastic Scattering strongly interacted with each other. Further ISR measurements utilizing inclusive single or pairs of hadrons established that high p T particles are produced from states with two roughly back-to-back jets which are the result of scattering of constituents of the nucleons as described by Quantum Chromodynamics (QCD), which was developed during the course of these measurements. These techniques, which are the only practical method to study hard-scattering and jet phenomena in Au+Au central collisions at RHIC energies, are reviewed, as an introduction to present RHIC measurements
Fabrication of single phase 2D homologous perovskite microplates by mechanical exfoliation
Li, Junze; Wang, Jun; Zhang, Yingjun; Wang, Haizhen; Lin, Gaoming; Xiong, Xuan; Zhou, Weihang; Luo, Hongmei; Li, Dehui
2018-04-01
The two-dimensional (2D) Ruddlesden-Popper type perovskites have attracted intensive interest for their great environmental stability and various potential optoelectronic applications. Fundamental understanding of the photophysical and electronic properties of the 2D perovskites with pure single phase is essential for improving the performance of the optoelectronic devices and designing devices with new architectures. Investigating the optical and electronic properties of these materials with pure single phase is required to obtain pure single phase 2D perovskites. Here, we report on an alternative approach to fabricate (C4H9NH3)2(CH3NH3) n-1Pb n I3n+1 microplates with pure single n-number perovskite phase for n > 2 by mechanical exfoliation. Micro-photoluminescence and absorption spectroscopy studies reveal that the as-synthesized 2D perovskite plates for n > 2 are comprised by dominant n-number phase and small inclusions of hybrid perovskite phases with different n values, which is supported by excitation power dependent photoluminescence. By mechanical exfoliation method, 2D perovskite microplates with the thickness of around 20 nm are obtained, which surprisingly have single n-number perovskite phase for n = 2-5. In addition, we have demonstrated that the exfoliated 2D perovskite microplates can be integrated with other 2D layered materials such as boron nitride, and are able to be transferred to prefabricated electrodes for photodetections. Our studies not only provide a strategy to prepare 2D perovskites with a single n-number perovskite phase allowing us to extract the basic optical and electronic parameters of pure phase perovskites, but also demonstrate the possibility to integrate the 2D perovskites with other 2D layered materials to extend the device’s functionalities.
International Nuclear Information System (INIS)
Sitenko, A.
1991-01-01
This book emerged out of graduate lectures given by the author at the University of Kiev and is intended as a graduate text. The fundamentals of non-relativistic quantum scattering theory are covered, including some topics, such as the phase-function formalism, separable potentials, and inverse scattering, which are not always coverded in textbooks on scattering theory. Criticisms of the text are minor, but the reviewer feels an inadequate index is provided and the citing of references in the Russian language is a hindrance in a graduate text
Single-crystal elasticity of diaspore, AlOOH, to 12 GPa by Brillouin scattering
Jiang, Fuming; Majzlan, Juraj; Speziale, Sergio; He, Duanwei; Duffy, Thomas S.
2008-11-01
The high-pressure elasticity of diaspore (AlOOH) has been determined by Brillouin spectroscopy to 12 GPa in diamond anvil cells. Experiments were carried out using a 16:3:1 methanol-ethanol-water mixture as pressure medium, and ruby as pressure standard. Acoustic velocities were measured in three roughly orthogonal planes at ambient and eight elevated pressures. The nine individual elastic stiffness constants of the orthorhombic crystal were obtained by fitting the velocity data to Christoffel's equation. Aggregate elastic moduli and pressure derivatives were calculated from the Cijs by fits to Eulerian finite strain equations, yielding: K=152(1) GPa, G0 = 117.2(5) GPa, (/∂P)T=3.7(1), (=1.5(1) for the Voigt-Reuss-Hill average. All individual Cijs increase with pressure but C23 and C55 exhibit anomalously low pressure derivatives. From calculated linear compressibilities, the a-axis is the most compressible. The b-axis becomes the least compressible axis at high pressures. Over the examined pressure range, the azimuthal P-wave anisotropy decreased from 22% to 16%, while the azimuthal S-wave anisotropy increased from 15% to 21%. Both volume and axial compression curves calculated using our Brillouin results are in good agreement with the results from static compression studies. High-pressure sound velocities in diaspore exceed those of other hydrous minerals as well as many anhydrous phases relevant to Earth's upper mantle.
Mask-based approach to phasing of single-particle diffraction data.
Lunin, Vladimir Y; Lunina, Natalia L; Petrova, Tatiana E; Baumstark, Manfred W; Urzhumtsev, Alexandre G
2016-01-01
A Monte Carlo-type approach for low- and medium-resolution phasing of single-particle diffraction data is suggested. Firstly, the single-particle phase problem is substituted with the phase problem for an imaginary crystal. A unit cell of this crystal contains a single isolated particle surrounded by a large volume of bulk solvent. The developed phasing procedure then generates a large number of connected and finite molecular masks, calculates their Fourier coefficients, selects the sets with magnitudes that are highly correlated with the experimental values and finally aligns the selected phase sets and calculates the averaged phase values. A test with the known structure of monomeric photosystem II resulted in phases that have 97% correlation with the exact phases in the full 25 Å resolution shell (1054 structure factors) and correlations of 99, 94, 81 and 79% for the resolution shells ∞-60, 60-40, 40-30 and 30-25 Å, respectively. The same procedure may be used for crystallographic ab initio phasing.
Di Biagio, C.; Formenti, P.; Caponi, L.; Cazaunau, M.; Pangui, E.; Journet, E.; Nowak, S.; Caquineau, S.; Andreae, M. O.; Kandler, K.; Saeed, T.; Piketh, S.; Seibert, D.; Williams, E.; Balkanski, Y.; Doussin, J. F.
2017-12-01
Mineral dust is one of the most abundant aerosol species in the atmosphere and strongly contributes to the global and regional direct radiative effect. Still large uncertainties persist on the magnitude and overall sign of the dust direct effect, where indeed one of the main unknowns is how much mineral dust absorbs light in the shortwave (SW) spectral range. Aerosol absorption is represented both by the imaginary part (k) of the complex refractive index or the single scattering albedo (SSA, i.e. the ratio of the scattering to extinction coefficient). In this study we present a new dataset of SW complex refractive indices and SSA for mineral dust aerosols obtained from in situ measurements in the 4.2 m3 CESAM simulation chamber at LISA (Laboratoire Interuniversitaire des Systemes Atmospheriques) in Créteil, France. Investigated dust aerosol samples were issued from major desert sources worldwide, including the African Sahara and Sahel, Eastern Asia, the Middle East, Southern Africa, Australia, and the Americas, with differing iron oxides content. Results from the present study provide a regional mapping of the SW absorption by dust and show that the imaginary part of the refractive index largely varies (by up to a factor 6, 0.003-0.02 at 370 nm and 0.001-0.003 at 950 nm) for the different source areas due to the change in the particle iron oxide content. The SSA for dust varies between 0.75-0.90 at 370 nm and 0.95-0.99 at 950 nm, with the largest absorption observed for Sahelian and Australian dust aerosols. Our range of variability for k and SSA is well bracketed by already published literature estimates, but suggests that regional‒dependent values should be used in models. The possible relationship between k and the dust iron oxides content is investigated with the aim of providing a parameterization of the regional‒dependent dust absorption to include in climate models.
First- and second-order Raman scattering from MoTe2 single crystal
Caramazza, Simone; Collina, Arianna; Stellino, Elena; Ripanti, Francesca; Dore, Paolo; Postorino, Paolo
2018-02-01
We report on Raman experiments performed on a MoTe2 single crystal. The system belongs to the wide family of transition metal dichalcogenides which includes several of the most interesting two-dimensional materials for both basic and applied physics. Measurements were performed in the standard basal plane configuration, by placing the ab plane of the crystal perpendicular to the wave vector k i of the incident beam to explore the in-plane vibrational modes, and in the edge plane configuration with k i perpendicular to the crystal c axis, thus mainly exciting out-of-plane modes. For both configurations we performed a polarization-dependent study of the first-order Raman components and detailed computation of the corresponding selection rules. We were thus able to provide a complete assignment of the observed first-order Raman peaks, in agreement with previous literature results. A thorough analysis of the second-order Raman bands, as observed in both basal and edge plane configurations, provides new information and allows a precise assignment of these spectral structures. In particular, we have observed and assigned Raman active modes of the M point of the Brillouin zone previously predicted by ab initio calculations but never previously measured.
Directory of Open Access Journals (Sweden)
Margarita Zakharova
2018-03-01
Full Text Available Single-shot grating-based phase-contrast imaging techniques offer additional contrast modalities based on the refraction and scattering of X-rays in a robust and versatile configuration. The utilization of a single optical element is possible in such methods, allowing the shortening of the acquisition time and increasing flux efficiency. One of the ways to upgrade single-shot imaging techniques is to utilize customized optical components, such as two-dimensional (2D X-ray gratings. In this contribution, we present the achievements in the development of 2D gratings with UV lithography and gold electroplating. Absorption gratings represented by periodic free-standing gold pillars with lateral structure sizes from 5 µm to 25 µm and heights from 5 µm to 28 µm have shown a high degree of periodicity and defect-free patterns. Grating performance was tested in a radiographic setup using a self-developed quality assessment algorithm based on the intensity distribution histograms. The algorithm allows the final user to estimate the suitability of a specific grating to be used in a particular setup.
Stability boundary analysis in single-phase grid-connected inverters with PLL by LTP theory
Salis, Valerio; Costabeber, Alessando; Cox, Stephen M.; Zanchetta, Pericle; Formentini, Andrea
2017-01-01
Stability analysis of power converters in AC net¬works is complex due to the non-linear nature of the conversion systems. Whereas interactions of converters in DC networks can be studied by linearising about the operating point, the extension of the same approach to AC systems poses serious challenges, especially for single-phase or unbalanced three-phase systems. A general method for stability analysis of power converters suitable for single-phase or unbalanced AC networks is presented in th...
LIDAR forest inventory with single-tree, double- and single-phase procedures
Robert C. Parker; David L. Evans
2009-01-01
Light Detection and Ranging (LIDAR) data at 0.5- to 2-m postings were used with doublesample, stratified inventory procedures involving single-tree attribute relationships in mixed, natural, and planted species stands to yield sampling errors (one-half the confidence interval expressed as a percentage of the mean) ranging from ±2.1 percent to ±11.5...
International Nuclear Information System (INIS)
Ishii, M.; Kataoka, I.
1983-03-01
Scaling criteria for a natural circulation loop under single phase and two-phase flow conditions have been derived. For a single phase case the continuity, integral momentum, and energy equations in one-dimensional area average forms have been used. From this, the geometrical similarity groups, friction number, Richardson number, characteristic time constant ratio, Biot number, and heat source number are obtained. The Biot number involves the heat transfer coefficient which may cause some difficulties in simulating the turbulent flow regime. For a two-phase flow case, the similarity groups obtained from a perturbation analysis based on the one-dimensional drift-flux model have been used. The physical significance of the phase change number, subcooling number, drift-flux number, friction number are discussed and conditions imposed by these groups are evaluated. In the two-phase flow case, the critical heat flux is one of the most important transients which should be simulated in a scale model. The above results are applied to the LOFT facility in case of a natural circulation simulation. Some preliminary conclusions on the feasibility of the facility have been obtained
Energy Technology Data Exchange (ETDEWEB)
Ishii, M.; Kataoka, I.
1983-03-01
Scaling criteria for a natural circulation loop under single phase and two-phase flow conditions have been derived. For a single phase case the continuity, integral momentum, and energy equations in one-dimensional area average forms have been used. From this, the geometrical similarity groups, friction number, Richardson number, characteristic time constant ratio, Biot number, and heat source number are obtained. The Biot number involves the heat transfer coefficient which may cause some difficulties in simulating the turbulent flow regime. For a two-phase flow case, the similarity groups obtained from a perturbation analysis based on the one-dimensional drift-flux model have been used. The physical significance of the phase change number, subcooling number, drift-flux number, friction number are discussed and conditions imposed by these groups are evaluated. In the two-phase flow case, the critical heat flux is one of the most important transients which should be simulated in a scale model. The above results are applied to the LOFT facility in case of a natural circulation simulation. Some preliminary conclusions on the feasibility of the facility have been obtained.
Phase Concentration Determination of Fe16N2 Using State of the Art Neutron Scattering Techniques
Bennett, S. P.; Feygenson, M.; Jiang, Y.; Zande, B. J.; Zhang, X.; Sankar, S. G.; Wang, J. P.; Lauter, V.
2016-06-01
Due to limitations on the availability of rare earth elements it is imperative that new high energy product rare earth free permanent magnet materials are developed for the next generation of energy systems. One promising low cost permanent magnet candidate for a high energy magnet is α″-Fe16N2, whose giant magnetic moment has been predicted to be well above any other from conventional first principles calculations. Despite its great promise, the α″ phase is metastable; making synthesis of the pure phase difficult, resulting in less than ideal magnetic characteristics. This instability gives way to a slew of possible secondary phases (i.e. α-Fe, Fe2O3, Fe8N, Fe4N, etc.) whose concentrations are difficult to detect by conventional x-ray diffraction. Here we show how high resolution neutron diffraction and polarized neutron reflectometry can be used to extract the phase concentration ratio of the giant magnetic phase from ultra-small powder sample sizes (~0.1 g) and thin films. These studies have led to the discovery of promising fabrication methods for both homogeneous thin films, and nanopowders containing the highest reported to date (>95%) phase concentrations of room temperature stable α″-Fe16N2.
SINGLE PHASE ANALYTICAL MODELS FOR TERRY TURBINE NOZZLE
Energy Technology Data Exchange (ETDEWEB)
Zhao, Haihua; Zhang, Hongbin; Zou, Ling; O' Brien, James
2016-11-01
benchmarked with CFD simulations. The analytical models generally agree well with the experimental data and CFD simulations. The analytical models are suitable for implementation into a reactor system analysis code or severe accident code as part of mechanistic and dynamical models to understand the RCIC behaviors. The cases with two-phase flow at the turbine inlet will be pursued in future work.
Ion beam induced single phase nanocrystalline TiO2 formation
Rukade, Deepti A.; Tribedi, L. C.; Bhattacharyya, Varsha
2014-06-01
Single phase TiO2 nanostructures are fabricated by oxygen ion implantation (60 keV) at fluence ranging from 1×1016 ions/cm2 to 1×1017 ions/cm2 in titanium thin films deposited on fused silica substrate and subsequent thermal annealing in argon atmosphere. GAXRD and Raman spectroscopy study reveals formation of single rutile phases of TiO2. Particle size is found to vary from 29 nm to 35 nm, establishing nanostructure formation. Nanostructure formation is also confirmed by the quantum confinement effect manifested by the blueshift of the UV-vis absorption spectra. Photoluminescence spectra show peaks corresponding to TiO2 rutile phase and reveal the presence of oxygen defects due to implantation. The controlled synthesis of single phase nanostructure is attributed to ion induced defects and post-implantation annealing. It is observed that the size of the nanostructures formed is strongly dependent on the ion fluence.
Fair, K M; Ford, M J
2015-10-30
We report density functional theory calculations for single layer MoS2 in its 2H, semiconducting and 1T metallic phases in order to understand the relative stability of these two phases and transition between them in the presence of adsorbed lithium atoms and under compressive strain. We have determined the diffusion barriers between the two phases and demonstrate how the presence of Li adatoms or strain can significantly reduce these barriers. We show that the 2H and 1T structures have the same energy under 15% biaxial, compressive strain. This is the same strain value posited by Lin et al (2014 Nat. Nanotechnology 9 391-396) for their intermediate α phase. Calculations of the 1T and 2H permittivity and electron energy loss spectrum are also performed and characterized.
Raman scattering study of the ferroelectric phase transition in BaT i2O5
Tsukada, Shinya; Fujii, Yasuhiro; Yoneda, Yasuhiro; Moriwake, Hiroki; Konishi, Ayako; Akishige, Yukikuni
2018-02-01
Uniaxial ferroelectric BaT i2O5 with a Curie temperature TC of 743 K was investigated to clarify its paraelectric-ferroelectric phase-transition behavior. The mechanism is discussed on the basis of the structure from short to long ranges determined by synchrotron x-ray diffraction and the lattice dynamics probed by Raman spectroscopy. BaT i2O5 is regarded as a homogeneous system, and the lattice dynamics can be interpreted by the selection rules and tensor properties of the homogeneous structure. Angle-resolved polarized Raman spectroscopy clearly shows that an A -mode-type overdamped phonon plays the key role in the phase transition. Using a combination of experimental results and first-principles calculations, we explain the phase transition as follows: In one of three Ti O6 octahedral units, Ti vibrates along the b axis opposite an oxygen octahedral unit with large damping in the paraelectric phase, whereas this vibration is frozen in the ferroelectric phase, leading to a change in the space group from nonpolar C 2 /m to polar C 2 .
System and method for single-phase, single-stage grid-interactive inverter
Liu, Liming; Li, Hui
2015-09-01
The present invention provides for the integration of distributed renewable energy sources/storages utilizing a cascaded DC-AC inverter, thereby eliminating the need for a DC-DC converter. The ability to segment the energy sources and energy storages improves the maintenance capability and system reliability of the distributed generation system, as well as achieve wide range reactive power compensation. In the absence of a DC-DC converter, single stage energy conversion can be achieved to enhance energy conversion efficiency.
Small angle neutron scattering study of the magnetic flux-line lattice in single crystal 2H-NbSe2
DEFF Research Database (Denmark)
Gammel, P.L.; Huse, D.A.; Kleiman, R.N.
1994-01-01
We report on a small angle neutron scattering study of the flux-line lattice in single crystal 2H-NbSe2. As the magnetic field is tilted away from the crystalline c axis, we find distortions in the flux lattice as would be expected for a mass anisotropy GAMMA = 10.1 +/- 0.9. However, we find...
Energy Technology Data Exchange (ETDEWEB)
Yang Yongxu (Dept. of Physics, Guangxi Normal Univ., Guilin (China)); Li Qingrun (CCAST (World Lab.), Inst. of High Energy Physics, Academia Sinica, Beijing (China))
1993-02-20
The differential cross-sections for [alpha]+[sup 16]O elastic scattering near E/A=12 and 7MeV have been calculated employing a single-folding potential based on the [alpha]-particle model for [sup 16]O. The calculated results are in good agreement with the experimental data. (orig.).
Directory of Open Access Journals (Sweden)
Boucher Yann G.
2017-01-01
Full Text Available In terms of Linear Algebra, a directional coupler between a single-mode waveguide and a two-mode waveguide can be thought of as formally equivalent to a set of three mutually coupled single-mode waveguides. Its responses, easily derived in the frame of ternary Coupled-Mode Theory, are used to establish analytically the scattering parameters of a hybrid ring-based modal multiplexer.
International Nuclear Information System (INIS)
Kerner, Boris S; Klenov, Sergey L; Hiller, Andreas
2006-01-01
Based on empirical and numerical microscopic analyses, the physical nature of a qualitatively different behaviour of the wide moving jam phase in comparison with the synchronized flow phase-microscopic traffic flow interruption within the wide moving jam phase-is found. A microscopic criterion for distinguishing the synchronized flow and wide moving jam phases in single vehicle data measured at a single freeway location is presented. Based on this criterion, empirical microscopic classification of different local congested traffic states is performed. Simulations made show that the microscopic criterion and macroscopic spatiotemporal objective criteria lead to the same identification of the synchronized flow and wide moving jam phases in congested traffic. Microscopic models in the context of three-phase traffic theory have been tested based on the microscopic criterion for the phases in congested traffic. It is found that microscopic three-phase traffic models can explain both microscopic and macroscopic empirical congested pattern features. It is obtained that microscopic frequency distributions for vehicle speed difference as well as fundamental diagrams and speed correlation functions can depend on the spatial co-ordinate considerably. It turns out that microscopic optimal velocity (OV) functions and time headway distributions are not necessarily qualitatively different, even if local congested traffic states are qualitatively different. The reason for this is that important spatiotemporal features of congested traffic patterns are lost in these as well as in many other macroscopic and microscopic traffic characteristics, which are widely used as the empirical basis for a test of traffic flow models, specifically, cellular automata traffic flow models
Phase discrimination in CdSe structures by means of Raman scattering
Energy Technology Data Exchange (ETDEWEB)
Cusco, R.; Artus, L. [Institut Jaume Almera (ICTJA-CSIC), Consejo Superior de Investigaciones Cientificas, Lluis Sole i Sabaris s.n., 08028 Barcelona (Spain); Consonni, V. [Universite Grenoble Alpes and CNRS, LMGP, 38016 Grenoble (France); Bellet-Amalric, E. [Universite Grenoble Alpes and CEA, INAC-PHEILQS, Nanophysique et Semiconducteurs Group, 38000 Grenoble (France); Andre, R. [Universite Grenoble Alpes and CNRS, Institut Neel, Nanophysique et Semiconducteurs Group, 38000 Grenoble (France)
2017-05-15
Raman spectra of epitaxial layers of CdSe grown by molecular beam epitaxy have been measured for the cubic (zincblende) and hexagonal (wurtzite) phases. The Raman spectra are examined in the light of density functional calculations for these two highly similar structures. Characteristic Raman frequencies and spectral features associated with the different symmetry are discussed and reliable criteria for phase discrimination based on Raman spectroscopy are proposed. Although LO frequencies are virtually identical in both structures and may be affected by size effects, the observation of a low energy E{sub 2} mode at 33 cm{sup -1} unambiguously identifies the wurtzite structure and can be used as a specific fingerprint to distinguish between these two phases in CdSe-based nanostructures. The slightly lower LO frequency measured in the zincblende epitaxial layer is ascribed to residual tensile strain. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Phases of phosphatidyl ethanolamine monolayers studied by synchrotron x-ray scattering
DEFF Research Database (Denmark)
Helm, C.A.; Tippmann-Krayer, P.; Möhwald, H.
1991-01-01
For the first time, phospholid monolayers at the air/water interface have been studied by x-ray diffraction and reflection all along the isotherm from the laterally isotropic fluid (the so-called LE phase) to the ordered phases. The model used to analyze the data, and the accuracy of the parameters...... deduced, were tested by comparing the results obtained with two lipids having the same head group but different chain lengths. Compression of the fluid phase leads predominantly to a change of thickness of the hydrophobic moiety, much less of its density, with the head group extension remaining constant....... The main transition involves a considerable increase (approximately 10%) of the electron density in the hydrophobic region, a dehydration of the head group and a positional ordering of the aliphatic tails, albeit with low coherence lengths (approximately 10 spacings). On further compression of the film...
Pan, Jianjun; Heberle, Frederick A.; Tristram-Nagle, Stephanie; Szymanski, Michelle; Koepfinger, Mary; Katsaras, John; Kučerka, Norbert
2013-01-01
We have determined the molecular structures of commonly used phosphatidylglycerols (PGs) in the commonly accepted biologically relevant fluid phase. This was done by simultaneously analyzing small angle neutron and X-ray scattering data, with the constraint of measured lipid volumes. We report the temperature dependence of bilayer parameters obtained using the one-dimensional scattering density profile model – which was derived from molecular dynamics simulations – including the area per lipid, the overall bilayer thickness, as well as other intrabilayer parameters (e.g., hydrocarbon thickness). Lipid areas are found to be larger than their phosphatidylcholine (PC) counterparts, a result likely due to repulsive electrostatic interactions taking place between the charged PG headgroups even in the presence of sodium counterions. In general, PG and PC bilayers show a similar response to changes in temperature and chain length, but differ in their response to chain unsaturation. For example, compared to PC bilayers, the inclusion of a first double bond in PG lipids results in a smaller incremental change to the area per lipid and bilayer thickness. However, the extrapolated lipid area of saturated PG lipids to infinite chain length is found to be similar to that of PCs, an indication of the glycerol–carbonyl backbone's pivotal role in influencing the lipid–water interface. PMID:22583835
Nucleon-nucleon scattering phase shifts. [Resonance, 0 to 800 MeV, review
Energy Technology Data Exchange (ETDEWEB)
Bryan, R.
1978-01-01
Here are presented 0 to 800 MeV nucleon-nucleon elastic and inelastic phase parameters derived by several groups: Arndt and Roper; Hoshizaki; Bugg; Bystricky, Lechanoine, and Lehar; and Bryan, Clark, and VerWest. Resonant-like behavior appears in the /sup 1/D/sub 2/ and /sup 3/F/sub 3/ states above the inelastic threshold in Hoshizaki's analysis but not in Arndt and Roper's. The np data are inadequate to permit determination of the I = O phase parameters above 600 MeV. 27 references.
Polarization periodicity in the B1 columnar phase determined by resonant x-ray scattering
Energy Technology Data Exchange (ETDEWEB)
Folcia, C.L.; Pindak, R.; Ortega, J.; Etxebarria, J.; Pan, L.; Wang, S.; Huang, C.C.; Ponsinet, V.; Barois, P. and Gimeno, N.
2011-07-14
We report structural results that evidence the polarization distribution of the blocks in the columnar phase of an achiral bent-core liquid crystal. The study was performed using resonant x-ray diffraction at the sulfur K edge on oriented samples aligned on substrates. The extra periodicity is revealed through the violation of the systematic extinction rule of the structural symmetry group along the experimentally accessible diffraction direction. Further data obtained from the polarization analysis of a resonant reflection give information concerning the transition mechanism between B{sub 1} and B{sub 2} phases.
Polarization Periodicity in the B(1) Columnar Phase Determined by Resonant X-ray Scattering
Energy Technology Data Exchange (ETDEWEB)
C Folcia; J Ortega; J Etxebarria; L Pan; S Wang; C Huang; V Ponsinet; P Barois; R Pindak; N Gimeno
2011-12-31
We report structural results that evidence the polarization distribution of the blocks in the columnar phase of an achiral bent-core liquid crystal. The study was performed using resonant x-ray diffraction at the sulfur K edge on oriented samples aligned on substrates. The extra periodicity is revealed through the violation of the systematic extinction rule of the structural symmetry group along the experimentally accessible diffraction direction. Further data obtained from the polarization analysis of a resonant reflection give information concerning the transition mechanism between B{sub 1} and B{sub 2} phases.
International Nuclear Information System (INIS)
Vu, H. X.; DuBois, D. F.; Bezzerides, B.
2007-01-01
The rapid onset, with increasing laser intensity, of levels of backward stimulated Raman scattering (BSRS) exceeding linear convective predictions, from single laser hot spots was predicted by simulations [Vu et al., Phys. Plasmas 9, 1745 (2002)], and has been observed [Montgomery et al., Phys. Plasmas 9, 2311 (2002)] in nonlinear regimes dominated by electron trapping. A theory for this inflation threshold is given here. The threshold is the result of competition between velocity diffusion and trapping, and is exceeded when the convectively amplified SRS Langmuir wave (LW) achieves an amplitude for which the coherent trapping velocity increment of electrons in the LW (the half-width of the trapping separatrix) exceeds the rms diffusion velocity (resulting from background plasma fluctuations), accumulated in one bounce time, for electrons with mean velocities near the phase velocity of the LW. The results of this theory, when the kinetic theory of the one-dimensional (1D) reduced-description particle-in-cell (RPIC) simulation is used, are in good agreement with a series of 1D RPIC simulations. The theory is naturally generalized to three dimensions, and is compatible with macroscopic laser interaction codes such as pF3d [Berger et al., Phys. Plasmas 5, 4337 (1998)]. Comparison of the LW trapping-induced inflation threshold to the LW threshold for the Langmuir decay instability provides an estimate for the transition between nonlinear saturation regimes. In an independent hot spot model of many hot spots, statistics suggests that the inflation threshold intensity will control the rapid onset of strong BSRS in laser beams smoothed by random phase plates
Reynolds, Philip A; McGillivray, Duncan J; Mata, Jitendra P; Yaron, Peter N; White, John W
2010-09-15
The changes in structure of high internal phase emulsions at low concentrations and at elevated temperature are reported for comparison with the same emulsions under conditions well away from instability. Small angle neutron scattering measurements on aqueous ammonium nitrate droplets dispersed in hexadecane and stabilized by very small quantities of a polyisobutylene-based surfactant (PIBSA) as well as related inverse micellar solutions in hexadecane, have been made as a function of temperature and surfactant concentration. Experimental conditions here favour larger and more deformable droplets than in previous studies. Besides the expected micelles and adsorbed surfactant, planar bilayers of micron lateral extent between touching droplets cover 20% of the droplet surface. Another difference from previous experiments is that the oil phase in the emulsions, and corresponding inverse micellar solutions are different in micellar radii and composition. The differences, and changes with surfactant concentration and temperature, are attributed to fractionation of the polydisperse PIBSA in the emulsions, but not the inverse micellar solutions. At low PIBSA concentration and high temperature the SANS shows emulsion decomposing into separate oil and aqueous phases. This occurs when the micelle concentration reaches a very small but measurable value. The inverse micelles may suppress by steric action long wavelength unstable capillary waves in the bilayers. Depletion repulsion forces here have a minor role in the emulsion stabilization. Copyright 2010 Elsevier Inc. All rights reserved.
Puig, Julieta; Williams, Roberto J J; Hoppe, Cristina E
2013-09-25
Paraffins are typical organic phase change materials (PCM) used for latent heat storage. For practical applications they must be encapsulated to prevent leakage or agglomeration during fusion. In this study it is shown that eicosane (C20H42 = C20) in the melted state could be dissolved in the hydrophobic domains of poly(dodecyl methacrylate) (PDMA) up to concentrations of 30 wt %, avoiding the need of encapsulation. For a 30 wt % solution, the heat of phase change was close to 69 J/g, a reasonable value for its use as a PCM. The fully converted solution remained transparent at 80 °C with no evidence of phase separation but became opaque by cooling as a consequence of paraffin crystallization. Heating above the melting temperature regenerated a transparent material. A high contrast ratio and abrupt transition between opaque and transparent states was observed for the 30 wt % blends, with a transparent state at 35 °C and an opaque state at 23 °C. This behavior was completely reproducible during consecutive heating/cooling cycles, indicating the possible use of this material as a thermally reversible light scattering (TRLS) film.
Cavanna, F; Touramanis, C
2017-01-01
ProtoDUNE-SP is the single-phase DUNE Far Detector prototype that is under construction and will be operated at the CERN Neutrino Platform (NP) starting in 2018. It was proposed to the CERN SPSC in June 2015 (SPSC-P-351) and was approved in December 2015 as experiment NP04 (ProtoDUNE). ProtoDUNE-SP, a crucial part of the DUNE effort towards the construction of the first DUNE 10-kt fiducial mass far detector module (17 kt total LAr mass), is a significant experiment in its own right. With a total liquid argon (LAr) mass of 0.77 kt, it represents the largest monolithic single phase LArTPC detector to be built to date. It is housed in an extension to the EHN1 hall in the North Area, where the CERN NP is providing a new dedicated charged-particle test beamline. ProtoDUNE-SP aims to take its first beam data before the LHC long shutdown (LS2) at the end of 2018. ProtoDUNE-SP prototypes the designs of most of the single-phase DUNE far detector module (DUNE-SP) components at a 1:1 scale, with an extrapolation of abo...
International Nuclear Information System (INIS)
Kiswanta; Edy Sumarno; Joko Prasetio W; Ainur Rosidi; G B Heru K
2013-01-01
Innovation design of BETA test loop has been done. BETA test loop is a research facility used as a support for experiments of reactor accident simulation. The innovation was performed to prepare experimental facilities in order to study flow of heat transfer in single-phase and two-phase flows. The design was executed by modifying new piping of UUB's primary system, addition of heat flux measurements and imaging thermal for easiness of experimental result analysis. UUB development and experiments were carried out to understand heat transfer process in the narrow gap of two-phase flow considering this phenomenon is one of the conditions postulated in PWR typed nuclear power plant accident scenario. The innovation design of BETA test loop is still in the planning stages so that the design has not been constructed. Piping systems made of SS-304 with the ability to use a maximum pressure of 10 bar with a diameter of % inch pipe to, from the calculation of minimal design that is 7.27 mm. If the tube SS-304 - ASTM B88 is the wall thickness of 0.083 inches. From this design it is indicated that the design is able to be fabricated and used for experimental study of heat transfer in single-phase and two-phase flows. (author)
Scattering resonances in a degenerate Fermi gas
DEFF Research Database (Denmark)
Challis, Katharine; Nygaard, Nicolai; Mølmer, Klaus
2009-01-01
We consider elastic single-particle scattering from a one-dimensional trapped two-component superfluid Fermi gas when the incoming projectile particle is identical to one of the confined species. Our theoretical treatment is based on the Hartree-Fock ground state of the trapped gas and a configur......We consider elastic single-particle scattering from a one-dimensional trapped two-component superfluid Fermi gas when the incoming projectile particle is identical to one of the confined species. Our theoretical treatment is based on the Hartree-Fock ground state of the trapped gas...... and a configuration-interaction description of the excitations. We determine the scattering phase shifts for the system and predict Fano-type scattering resonances that are a direct consequence of interatomic pairing. We describe the main characteristics of the scattering resonances and make a comparison...... with the results of BCS mean-field theory....
A simple and consistent equation of state for sodium in the single phase and two phase regions
International Nuclear Information System (INIS)
Breton, J.P.
1976-01-01
An equation of state valid over an extended temperature and density range has been derived. Then, the following properties have been deduced : coefficient of thermal expansion, isothermal coefficient of bulk compressibility, thermal pressure coefficient, heat capacity at constant pressure, at constant volume, along the saturation curve for liquid, for vapor, heat of vaporization, speed of sound, and finally the Mollier diagram and the entropy diagram. All the obtained properties are thermodynamically consistent and satisfy the basic relations of thermodynamics for both single phase and two-phase regions. Experimental results were always used when available. (auth.)
Scalable WDM phase regeneration in a single phase-sensitive amplifier through optical time lenses
DEFF Research Database (Denmark)
Guan, Pengyu; Da Ros, Francesco; Lillieholm, Mads
2018-01-01
elusive, constituting a key challenge, which must be overcome for optical regeneration to have any prospect of being adapted in actual communication systems. Here we report a scalable wavelength-division multiplexing (WDM) regeneration scheme for phase only regeneration, which satisfies the multichannel...
Use of Single-Layer g-C3N4/Ag Hybrids for Surface-Enhanced Raman Scattering (SERS).
Jiang, Jizhou; Zou, Jing; Wee, Andrew Thye Shen; Zhang, Wenjing
2016-09-30
Surface-enhanced Raman scattering (SERS) substrates with high activity and stability are desirable for SERS sensing. Here, we report a new single atomic layer graphitic-C 3 N 4 (S-g-C 3 N 4 ) and Ag nanoparticles (NPs) hybrid as high-performance SERS substrates. The SERS mechanism of the highly stable S-g-C 3 N 4 /Ag substrates was systematically investigated by a combination of experiments and theoretical calculations. From the results of XPS and Raman spectroscopies, it was found that there was a strong interaction between S-g-C 3 N 4 and Ag NPs, which facilitates the uniform distribution of Ag NPs over the edges and surfaces of S-g-C 3 N 4 nanosheets, and induces a charge transfer from S-g-C 3 N 4 to the oxidizing agent through the silver surface, ultimately protecting Ag NPs from oxidation. Based on the theoretical calculations, we found that the net surface charge of the Ag atoms on the S-g-C 3 N 4 /Ag substrates was positive and the Ag NPs presented high dispersibility, suggesting that the Ag atoms on the S-g-C 3 N 4 /Ag substrates were not likely to be oxidized, thereby ensuring the high stability of the S-g-C 3 N 4 /Ag substrate. An understanding of the stability mechanism in this system can be helpful for developing other effective SERS substrates with long-term stability.
Mei, Liang; Guan, Peng; Yang, Yang; Kong, Zheng
2017-08-07
An 808 nm single-band Mie scattering Scheimpflug lidar system is developed in Dalian, Northern China, for real-time, large-area atmospheric aerosol/particle remote sensing. Atmospheric measurement has been performed in urban area during a typical haze weather condition, and time-range distribution of atmospheric backscattering signal is recorded from March 18th to 22nd, 2017, by employing the Scheimpflug lidar system. Atmospheric extinction coefficient is then retrieved according to the Klett-inversion algorithm, while the boundary value is obtained by the slope-method in the far end where the atmosphere is homogeneous in a subinterval region. The correlation between the extinction coefficients retrieved from the Scheimpflug lidar technique and the PM10/PM2.5 concentrations measured by a conventional air pollution monitoring station is also studied. The good agreement between the measurement results, i.e., a correlation coefficient of 0.85, successfully demonstrates the feasibility and great potential of the Scheimpflug lidar technique for atmospheric studies and applications.
International Nuclear Information System (INIS)
Freund, A K; Rehm, C
2014-01-01
The present study has been conducted in the framework of the channel-cut crystal design for the Kookaburra ultra-small-angle neutron scattering (USANS) instrument to be installed at the OPAL reactor of ANSTO. This facility is based on the classical Bonse-Hart method that uses two multiple-reflection crystal systems. The dynamical theory of diffraction by perfect crystals distinguishes two cases: the Darwin case applying to infinitely thick crystals and the Ewald solution for very small absorption taking into account the reflection from the rear face of a plane-parallel crystal reflecting in Bragg geometry. The former is preferable because it yields narrower rocking curves. To prevent the neutrons to 'see' the rear face, grooves were machined into the backside of perfect Si test crystals for single reflection and filled with neutron absorbing material. These samples were examined at the S18 instrument of the Institut Laue-Langevin. Unexpectedly the crystals with empty slots showed an increase of the rocking curve width. When filling the slots with an absorber the widths decreased, but without reaching that of the Darwin curve. Understanding the results and achieving a successful crystal design call for the development of a theory that permits to describe neutron diffraction from crystals with a structured back face.
Freund, A. K.; Rehm, C.
2014-07-01
The present study has been conducted in the framework of the channel-cut crystal design for the Kookaburra ultra-small-angle neutron scattering (USANS) instrument to be installed at the OPAL reactor of ANSTO. This facility is based on the classical Bonse-Hart method that uses two multiple-reflection crystal systems. The dynamical theory of diffraction by perfect crystals distinguishes two cases: the Darwin case applying to infinitely thick crystals and the Ewald solution for very small absorption taking into account the reflection from the rear face of a plane-parallel crystal reflecting in Bragg geometry. The former is preferable because it yields narrower rocking curves. To prevent the neutrons to "see" the rear face, grooves were machined into the backside of perfect Si test crystals for single reflection and filled with neutron absorbing material. These samples were examined at the S18 instrument of the Institut Laue-Langevin. Unexpectedly the crystals with empty slots showed an increase of the rocking curve width. When filling the slots with an absorber the widths decreased, but without reaching that of the Darwin curve. Understanding the results and achieving a successful crystal design call for the development of a theory that permits to describe neutron diffraction from crystals with a structured back face.
Directory of Open Access Journals (Sweden)
E. I. Kassianov
2007-06-01
Full Text Available Multi-filter Rotating Shadowband Radiometers (MFRSRs provide routine measurements of the aerosol optical depth (τ at six wavelengths (0.415, 0.5, 0.615, 0.673, 0.870 and 0.94 μm. The single-scattering albedo (π_{0} is typically estimated from the MFRSR measurements by assuming the asymmetry parameter (g. In most instances, however, it is not easy to set an appropriate value of g due to its strong temporal and spatial variability. Here, we introduce and validate an updated version of our retrieval technique that allows one to estimate simultaneously π_{0} and g for different types of aerosol. We use the aerosol and radiative properties obtained during the Atmospheric Radiation Measurement (ARM Program's Aerosol Intensive Operational Period (IOP to validate our retrieval in two ways. First, the MFRSR-retrieved optical properties are compared with those obtained from independent surface, Aerosol Robotic Network (AERONET, and aircraft measurements. The MFRSR-retrieved optical properties are in reasonable agreement with these independent measurements. Second, we perform radiative closure experiments using the MFRSR-retrieved optical properties. The calculated broadband values of the direct and diffuse fluxes are comparable (~5 W/m^{2} to those obtained from measurements.
Femtosecond Coherent Anti-Stokes Raman Scattering Gas Phase Thermometry at 5 kHz
Fineman, Claresta; Lucht, Robert
2014-05-01
Understanding the thermal instabilities occurring in turbulent combustion, such as in modern gas turbine combustors, is critical for more reliable and fuel-efficient operation. Non-intrusive laser based spectroscopy methods have been documented as the techniques of choice for turbulent combustion diagnostics. Specifically, femtosecond coherent anti-Stokes Raman scattering (fs-CARS) thermometry has been established for temporal resolution of turbulent fluctuations in flame structure and provides accurate measurements across a wide range of temperatures. Experiments performed to date include 5 kHz pure vibrational N2 chirped probe-pulse fs-CARS thermometry on non-premixed hydrogen jet diffusion flames, methane jet diffusion flames, and the DLR gas turbine model combustor (GTMC). The fs-CARS signal generation process requires precise spatial and temporal overlap of tightly focused pulsed laser beams of less than 100 fs pulse duration. Here, signal loss due to beam steering, pressure fluctuations, or shear layer density gradients can become a problem. The effect of such interferences has been investigated using high velocity flow of compressed nitrogen gas from a converging-diverging nozzle. Resulting changes in fs-CARS spectra have been studied. Funding for this work was provided by the U.S. Department of Energy, Division of Chemical Sciences, Geosciences and Biosciences.
Fuentes-Edfuf, Yasser; Garcia-Lechuga, Mario; Puerto, Daniel; Florian, Camilo; Garcia-Leis, Adianez; Sanchez-Cortes, Santiago; Solis, Javier; Siegel, Jan
2017-07-04
Periodic structures of alternating amorphous-crystalline fringes have been fabricated in silicon using repetitive femtosecond laser exposure (800 nm wavelength and 120 fs duration). The method is based on the interference of the incident laser light with far- and near-field scattered light, leading to local melting at the interference maxima, as demonstrated by femtosecond microscopy. Exploiting this strategy, lines of highly regular amorphous fringes can be written. The fringes have been characterized in detail using optical microscopy combined modelling, which enables a determination of the three-dimensional shape of individual fringes. 2D micro-Raman spectroscopy reveals that the space between amorphous fringes remains crystalline. We demonstrate that the fringe period can be tuned over a range of 410 nm - 13 µm by changing the angle of incidence and inverting the beam scan direction. Fine control over the lateral dimensions, thickness, surface depression and optical contrast of the fringes is obtained via adjustment of pulse number, fluence and spot size. Large-area, highly homogeneous gratings composed of amorphous fringes with micrometer width and millimeter length can readily be fabricated. The here presented fabrication technique is expected to have applications in the fields of optics, nanoelectronics, and mechatronics and should be applicable to other materials.
Neutron scattering observations on the magnetic phases of rareearth ternary superconductors
International Nuclear Information System (INIS)
Moncton, D.E.
1979-01-01
A number of ternary compounds become superconducting even though they contain a chemically ordered sublattice of magnetic rare-earth ions. Studies of the physical properties of these materials have revealed anomalies below T/sub c/ which have been attributed to magentic ordering transitions. Usng neutron spectrometers at the Brookhaven National Laboratory, a group of us has demonstrated that simple magnetic structures with long-range order do occur, and we have solved some of the magnetic structures of these superconductors. Specifically, we have found that in DyMo 6 S 8 and TbMo 6 S 8 an antiferromagnetic structure coexists with superconductivity. In two other compounds, ErRh 4 B 4 and HoMo 6 S 8 we have found that the development of ferromagnetism is responsible for the quenching of superconductivity. A study of the critical magnetic neutron scattering near the superconducting → ferromagnetic transitions shows the presence of fluctuations into a state with an oscillatory magnetization of wave length lambda = 100A
Vervoort, N; Daemen, D; Török, G
2008-05-02
In pharmaceutical industry ultraviolet (UV) detection is often used as the preferred detection technique in HPLC analysis since most pharmaceutical compounds possess a UV-absorbing chromophore. However, in case the active pharmaceutical ingredient (API) does not have a UV-absorbing chromophore, or if some of the impurities present lack a chromophore, they will not be detected in routine HPLC analysis employing only a UV detector and alternative detection schemes have to be used. Refractive index detection or mass spectroscopy (MS) can be used but these detectors have their intrinsic weaknesses, such as lack of sensitivity or high cost. With the appearance of semi-universal techniques such as evaporative light scattering detection (ELSD), and more recent, charged aerosol detection (CAD), detection of non-UV-absorbing compounds became feasible without having to resort to such complex or costly detection methods. This paper evaluates the different performance characteristics such as sensitivity, linearity, accuracy and precision of both the ELSD and CAD detector coupled to HPLC. One disadvantage of this type of detector is the non-linear response behaviour which makes direct linear regression for making calibration curves inaccurate.
Current Status of Single-Agent Phase I Trials in Japan: Toward Globalization.
Mizugaki, Hidenori; Yamamoto, Noboru; Fujiwara, Yutaka; Nokihara, Hiroshi; Yamada, Yasuhide; Tamura, Tomohide
2015-06-20
In Japan, phase I trials, except first-in-human trials, are usually initiated from approximately 50% of the maximum-tolerated dose (MTD) or maximum administered dose (MAD) determined during the initial phase I trials in North America and Europe (the West). However, the key findings of phase I trials in Japan and the West, such as dose-limiting toxicity (DLT) profiles and MTD or MAD levels, have not been compared. We retrospectively analyzed data for patients enrolled onto single-agent phase I trials at the National Cancer Center Hospital between 1995 and 2012. DLT profiles, MTDs, and MADs of single-agent phase I trials in Japan were compared with those from trials in the West that were obtained from the literature. A total of 777 patients were enrolled onto 54 single-agent phase I trials, including five first-in-human trials. DLTs were observed in 11.1% of the patients. Importantly, 66.4% of the DLTs were observed within a dose range (80% to 120%) similar to those reported for the trials in the West. The majority of MTDs or MADs could be considered similar between patients, and 80.3% of the drugs had similar MTDs or MADs in the West. The toxicity profiles of single-agent phase I agents determined from trials conducted in Japan were comparable to those obtained from trials in the West. We believe that phase I trials in Japan could be conducted over timelines similar to those in the West, allowing for global or parallel phase I clinical trials. © 2015 by American Society of Clinical Oncology.
High magnetic field susceptibility and neutron scattering measurements for ZnFe2O4 single crystal
International Nuclear Information System (INIS)
Kamazawa, Kazuya; Nakajima, Kenji; Kohn, Key; Tsunoda, Yorihiko
2004-01-01
We studied field dependences of magnetic susceptibility and neutron scattering measurements for frustrated normal spinel ZnFe 2 O 4 . Although a peak which is similar to the antiferromagnetic transition is observed at 13 K in the magnetic susceptibility, there is no magnetic long-range order in our neutron scattering measurements. When we measure the magnetic susceptibility under the high magnetic field, the peak position moves toward the high temperature. In the neutron scattering measurements, magnetic diffuse scattering around the nuclear Bragg peaks disappear under the magnetic field of 3 T
The Influence of phase-locked loop on the stability of single-phase grid-connected inverter
DEFF Research Database (Denmark)
Zhang, Chong; Wang, Xiongfei; Blaabjerg, Frede
2015-01-01
admittance of single-phase current-controlled inverters with different grid stiffness is analyzed in this paper. It shows that the PLL introduces a negative paralleled admittance into the output admittance of the inverter, which may lead to unintentional low-order harmonic oscillation in a weak grid...... for avoiding the PLL induced instability in single-phase inverters. At last the relationship between PLL bandwidth and the Short Circuit Ratio (SCR) of the grid has been derived to guide the design of the PLL. Experimental results are presented in order to verify this analysis, and the resonant frequencies can...... be predicted by the method. The possible instability due to different PLL bandwidth is also demonstrated....
An Investigation of Attenuation, Scattering and Site Effects on Regional Phases.
1981-03-23
sedimentary sites (circles) relative to hard rock sites (squares) located on the shield or stable platform region of North America. Triangles denote the...resting on granitic or consolidated lower Paleozoic rocks having no more than 50 m of overlying unconsolidated rock cover. All sites not satisfying...investigate amplification of regional phases at sedimentary sites (circles) relative to hard rock sites (squares) located on the shield or stable platform
International Nuclear Information System (INIS)
Hayden, C.C.; Chandler, D.W.
1995-01-01
Results are presented from femtosecond time-resolved coherent Raman experiments in which we excite and monitor vibrational coherence in gas-phase samples of benzene and 1,3,5-hexatriene. Different physical mechanisms for coherence decay are seen in these two molecules. In benzene, where the Raman polarizability is largely isotropic, the Q branch of the vibrational Raman spectrum is the primary feature excited. Molecules in different rotational states have different Q-branch transition frequencies due to vibration--rotation interaction. Thus, the macroscopic polarization that is observed in these experiments decays because it has many frequency components from molecules in different rotational states, and these frequency components go out of phase with each other. In 1,3,5-hexatriene, the Raman excitation produces molecules in a coherent superposition of rotational states, through (O, P, R, and S branch) transitions that are strong due to the large anisotropy of the Raman polarizability. The coherent superposition of rotational states corresponds to initially spatially oriented, vibrationally excited, molecules that are freely rotating. The rotation of molecules away from the initial orientation is primarily responsible for the coherence decay in this case. These experiments produce large (∼10% efficiency) Raman shifted signals with modest excitation pulse energies (10 μJ) demonstrating the feasibility of this approach for a variety of gas phase studies. copyright 1995 American Institute of Physics
Compton scattering study and electronic structure of different phases of NH4NO3
International Nuclear Information System (INIS)
Jain, Pradeep; Sahariya, Jagrati; Ahuja, B L
2013-01-01
In this paper, we present energy bands, density of states and the nature of hydrogen bonding in different temperature-dependent phases of NH 4 NO 3 , namely phases II (357–398 K), III (305–357 K) and IV (257–305 K), using the full potential linearized augmented plane wave and linear combination of atomic orbitals (LCAO) methods. Both band structure calculations show the insulating character of the II–IV phases of NH 4 NO 3 . In addition, we have reported the isotropic Compton profile of NH 4 NO 3 (IV) measured using 661.65 keV γ-radiation from a 137 Cs isotope. The experimental momentum density has been compared with that based on density functional theory (DFT) and Hartree–Fock schemes within the LCAO method. It is seen that the LCAO with hybridization of DFT and Hartree–Fock (so-called B3LYP) gives better agreement with the present Compton profile measurement. (paper)
Compton scattering study and electronic structure of different phases of NH4NO3
Jain, Pradeep; Sahariya, Jagrati; Ahuja, B. L.
2013-06-01
In this paper, we present energy bands, density of states and the nature of hydrogen bonding in different temperature-dependent phases of NH4NO3, namely phases II (357-398 K), III (305-357 K) and IV (257-305 K), using the full potential linearized augmented plane wave and linear combination of atomic orbitals (LCAO) methods. Both band structure calculations show the insulating character of the II-IV phases of NH4NO3. In addition, we have reported the isotropic Compton profile of NH4NO3(IV) measured using 661.65 keV γ-radiation from a 137Cs isotope. The experimental momentum density has been compared with that based on density functional theory (DFT) and Hartree-Fock schemes within the LCAO method. It is seen that the LCAO with hybridization of DFT and Hartree-Fock (so-called B3LYP) gives better agreement with the present Compton profile measurement.
Reliability Evaluation of a Single-phase H-bridge Inverter with Integrated Active Power Decoupling
DEFF Research Database (Denmark)
Tang, Junchaojie; Wang, Haoran; Ma, Siyuan
2016-01-01
Various power decoupling methods have been proposed recently to replace the DC-link Electrolytic Capacitors (E-caps) in single-phase conversion system, in order to extend the lifetime and improve the reliability of the DC-link. However, it is still an open question whether the converter level...... reliability becomes better or not, since additional components are introduced and the loading of the existing components may be changed. This paper aims to study the converter level reliability of a single-phase full-bridge inverter with two kinds of active power decoupling module and to compare...... it with the traditional passive DC-link solution. The converter level reliability is obtained by component level electro-thermal stress modeling, lifetime model, Weibull distribution, and Reliability Block Diagram (RBD) method. The results are demonstrated by a 2 kW single-phase inverter application....
Field-circuit analysis and measurements of a single-phase self-excited induction generator
Makowski, Krzysztof; Leicht, Aleksander
2017-12-01
The paper deals with a single-phase induction machine operating as a stand-alone self-excited single-phase induction generator for generation of electrical energy from renewable energy sources. By changing number of turns and size of wires in the auxiliary stator winding, an improvement of performance characteristics of the generator were obtained as regards no-load and load voltage of the stator windings as well as stator winding currents of the generator. Field-circuit simulation models of the generator were developed using Flux2D software package for the generator with shunt capacitor in the main stator winding. The obtained results have been validated experimentally at the laboratory setup using the single-phase capacitor induction motor of 1.1 kW rated power and 230 V voltage as a base model of the generator.
Benchmarking of grid fault modes in single-phase grid-connected photovoltaic systems
DEFF Research Database (Denmark)
Yang, Yongheng; Blaabjerg, Frede; Zou, Zhixiang
2012-01-01
Pushed by the booming installations of single-phase photovoltaic (PV) systems, the grid demands regarding the integration of PV systems are expected to be modified. Hence, the future PV systems should become more active with functionalities of low voltage ride-through (LVRT) and the grid support...... capability. The control methods, together with grid synchronization techniques, are responsible for the generation of appropriate reference signals in order to handle ride-through grid faults. Thus, it is necessary to evaluate the behaviors of grid synchronization methods and control possibilities in single...... phase systems under grid faults. The intent of this paper is to present a benchmarking of grid fault modes that might come in future single-phase PV systems. In order to map future challenges, the relevant detection and control strategies are discussed. Some faulty modes are studied experimentally...
International Nuclear Information System (INIS)
Ondrej Slezak; Milan Kalal; Hon Jin Kong
2010-01-01
Complete text of publication follows. Analytical description of an experimentally verified scheme leading to a phase-locked stimulated Brillouin scattering (SBS), used in a laser beam combination systems, is presented. The essential condition for the phase-locking effect for SBS is the fixation of the starting position and time of the acoustic Brillouin wave. It is shown that the starting position fixation of this acoustic wave may have its origin in a transient acoustic standing wave initiated by an arising optical interference field produced by the back-seeding concave mirror. This interference field leads to a stationary density modulation of the medium. However, the way to the formation of this density modulation leads via the acoustic standing wave. An appropriate solution, in the form of the standing wave, was obtained from solving the acoustic wave-equation using the electrostriction as a driving force. As a consequence of the damping term included in this equation the acoustic standing wave becomes gradually attenuated and contrary to the undamped solution published earlier, thus constitutes a truly transient phenomenon. Using a mathematical formalism similar to that which is used for the SBS description in the case of a random phase, the coupled equations describing the phase-locked SBS were derived. Contrary to the case without the back-seeding mirror, where the wave chosen from the thermal noise background subsequently plays the role of a trigger of the stimulated process, in this case it is replaced by the transient standing wave produced as a consequence of the presence of an optical interference field arisen in the focal region of the back-seeding concave mirror.
Phase retrieval from a single fringe pattern by using empirical wavelet transform
International Nuclear Information System (INIS)
Guo, Xiaopeng; Zhao, Hong; Wang, Xin
2015-01-01
Phase retrieval from a single fringe pattern is one of the key tasks in optical metrology. In this paper, we present a new method for phase retrieval from a single fringe pattern based on empirical wavelet transform. In the proposed method, a fringe pattern can be effectively divided into three components: nonuniform background, fringes and random noise, which are described in different sub-pass. So the phase distribution information can be robustly extracted from fringes representing a fundamental frequency component. In simulation and a practical projection fringes test, the performance of the present method is successfully verified by comparing with the conventional wavelet transform method in terms of both image quality and phase estimation errors. (paper)
Algorithms for image recovery calculation in extended single-shot phase-shifting digital holography
Hasegawa, Shin-ya; Hirata, Ryo
2018-02-01
The single-shot phase-shifting method of image recovery using an inclined reference wave has the advantages of reducing the effects of vibration, being capable of operating in real time, and affording low-cost sensing. In this method, relatively low reference angles compared with that in the conventional method using phase shift between three or four pixels has been required. We propose an extended single-shot phase-shifting technique which uses the multiple-step phase-shifting algorithm and the corresponding multiple pixels which are the same as that of the period of an interference fringe. We have verified the theory underlying this recovery method by means of Fourier spectral analysis and its effectiveness by evaluating the visibility of the image using a high-resolution pattern. Finally, we have demonstrated high-contrast image recovery experimentally using a resolution chart. This method can be used in a variety of applications such as color holographic interferometry.
Algorithms for image recovery calculation in extended single-shot phase-shifting digital holography
Hasegawa, Shin-ya; Hirata, Ryo
2018-04-01
The single-shot phase-shifting method of image recovery using an inclined reference wave has the advantages of reducing the effects of vibration, being capable of operating in real time, and affording low-cost sensing. In this method, relatively low reference angles compared with that in the conventional method using phase shift between three or four pixels has been required. We propose an extended single-shot phase-shifting technique which uses the multiple-step phase-shifting algorithm and the corresponding multiple pixels which are the same as that of the period of an interference fringe. We have verified the theory underlying this recovery method by means of Fourier spectral analysis and its effectiveness by evaluating the visibility of the image using a high-resolution pattern. Finally, we have demonstrated high-contrast image recovery experimentally using a resolution chart. This method can be used in a variety of applications such as color holographic interferometry.
Single-phase dual-energy CT urography in the evaluation of haematuria.
Ascenti, G; Mileto, A; Gaeta, M; Blandino, A; Mazziotti, S; Scribano, E
2013-02-01
To assess the value of a single-phase dual-energy computed tomography (DECT) urography protocol with synchronous nephrographic-excretory phase enhancement and to calculate the potential dose reduction by omitting the unenhanced scan. Eighty-four patients referred for haematuria underwent CT urography using a protocol that included single-energy unenhanced and dual-energy contrast-enhanced with synchronous nephrographic-excretory phase scans. DECT-based images [virtual unenhanced (VUE), weighted average, and colour-coded iodine overlay] were reconstructed. Opacification degree by contrast media of the upper urinary tract, and image quality of virtual unenhanced images were independently evaluated using a four-point scale. The diagnostic accuracy in detecting urothelial tumours on DECT-based images was determined. The dose of a theoretical dual-phase single-energy protocol was obtained by multiplying the effective dose of the unenhanced single-energy acquisition by two. Radiation dose saving by omitting the unenhanced scan was calculated. The degree of opacification was scored as optimal or good in 86.9% of cases (k = 0.72); VUE image quality was excellent or good in 83.3% of cases (k = 0.82). Sensitivity, specificity, positive predictive value, and negative predictive value for urothelial tumours detection were 85.7, 98.6, 92.3, and 97.1%. Omission of the unenhanced scan led to a mean dose reduction of 42.7 ± 5%. Single-phase DECT urography with synchronous nephrographic-excretory phase enhancement represents an accurate "all-in-one'' approach with a radiation dose saving up to 45% compared with a standard dual-phase protocol. Copyright © 2012 The Royal College of Radiologists. All rights reserved.
Single-phase dual-energy CT urography in the evaluation of haematuria
International Nuclear Information System (INIS)
Ascenti, G.; Mileto, A.; Gaeta, M.; Blandino, A.; Mazziotti, S.; Scribano, E.
2013-01-01
Aim: To assess the value of a single-phase dual-energy computed tomography (DECT) urography protocol with synchronous nephrographic–excretory phase enhancement and to calculate the potential dose reduction by omitting the unenhanced scan. Materials and methods: Eighty-four patients referred for haematuria underwent CT urography using a protocol that included single-energy unenhanced and dual-energy contrast-enhanced with synchronous nephrographic–excretory phase scans. DECT-based images [virtual unenhanced (VUE), weighted average, and colour-coded iodine overlay] were reconstructed. Opacification degree by contrast media of the upper urinary tract, and image quality of virtual unenhanced images were independently evaluated using a four-point scale. The diagnostic accuracy in detecting urothelial tumours on DECT-based images was determined. The dose of a theoretical dual-phase single-energy protocol was obtained by multiplying the effective dose of the unenhanced single-energy acquisition by two. Radiation dose saving by omitting the unenhanced scan was calculated. Results: The degree of opacification was scored as optimal or good in 86.9% of cases (k = 0.72); VUE image quality was excellent or good in 83.3% of cases (k = 0.82). Sensitivity, specificity, positive predictive value, and negative predictive value for urothelial tumours detection were 85.7, 98.6, 92.3, and 97.1%. Omission of the unenhanced scan led to a mean dose reduction of 42.7 ± 5%. Conclusion: Single-phase DECT urography with synchronous nephrographic–excretory phase enhancement represents an accurate “all-in-one’’ approach with a radiation dose saving up to 45% compared with a standard dual-phase protocol.
The Application Three-phase to Single-phase Z-Source Matrix Converter in Wind Turbine
Directory of Open Access Journals (Sweden)
vahid asadi rad
2017-01-01
Full Text Available In this paper a new idea of direct three-phase to single-phase Z-source matrix converter (impedance-source matrix converter applicable in stand-alone wind turbine is introduced. In the direct Z-source matrix converter amplitude of output voltage and frequency regulation are of importance to control system. In wind turbines, input voltage and frequency are usually changing due to wind speed variation that these alterations could be easily regulated by means of a direct Z-source matrix converter. A scheme is also offered to control the proposed direct three-phase to single-phase Z-source matrix converter. the control strategy would be able to adjust the output voltage and frequency at desired value as well as producing low THD (total harmonic distortion at the output voltage. The proposed structure and the control methodology are simulated using matlab simulink software and results are investigated and discussed to confirm the performance of the direct Z-source matrix converter in wind turbine.
Directory of Open Access Journals (Sweden)
Yeongsu Bak
2015-04-01
Full Text Available This paper presents an indirect matrix converter (IMC topology for hybrid electric vehicle (HEV application with three-phase and single-phase outputs. The HEV includes mechanical, electrical, control, and electrochemical systems among others. In the mechanical system, a traction motor and a compressor motor are used to drive the HEV. The traction motor and the compressor motor are usually operated as three-phase and single-phase motors, respectively. In this respect, a dual AC-drive system can operate the traction and the compressor motor simultaneously. Furthermore, compared to a conventional dual matrix converter system, the proposed topology can reduce the number of switches that the dual outputs share with a DC-link. The application of this system for HEV has advantages, like long lifetime and reduced volume due to the lack of a DC-link. The proposed control strategy and modulation schemes ensure the sinusoidal input and output waveforms and bidirectional power transmission. The proposed system for the HEV application is verified by simulation and experiments.
Single-carrier phase-disposition PWM implementation for multilevel flying capacitor converters
Ghias, Amer M.Y.M; Pou Félix, Josep; Capellá Frau, Gabriel José; Agelidis, Vassilios; Aguilera, Ricardo P; Meynard, Thierry A.
2015-01-01
This letter proposes a new implementation of phase-disposition pulse-width modulation (PD-PWM) for multilevel flying capacitor (FC) converters using a single triangular carrier. The proposed implementation is much simpler than conventional PD-PWM techniques based on multiple trapezoidal-shaped carriers, generates the same results as far as natural capacitor voltage balance is concerned and offers better quality line-to-line voltages when compared to phase-shifted PWM. The proposed algorithm i...
A re-look at critical factors influencing single-phase formation of Ba2 ...
Indian Academy of Sciences (India)
TECS
BaSnO3, B2O3 etc, single-phase 2: 9 has been achieved through solid-state route (Yu et al 1994; Lin and Robert. 1999; Wang et al 2003). It is recorded in literature that phase pure 2:9 ceramics without any stabilizing agent will result in better material for microwave dielectric applica- tions (Lin et al 1997; Lin and Robert ...
Single-phase power distribution system power flow and fault analysis
Halpin, S. M.; Grigsby, L. L.
1992-01-01
Alternative methods for power flow and fault analysis of single-phase distribution systems are presented. The algorithms for both power flow and fault analysis utilize a generalized approach to network modeling. The generalized admittance matrix, formed using elements of linear graph theory, is an accurate network model for all possible single-phase network configurations. Unlike the standard nodal admittance matrix formulation algorithms, the generalized approach uses generalized component models for the transmission line and transformer. The standard assumption of a common node voltage reference point is not required to construct the generalized admittance matrix. Therefore, truly accurate simulation results can be obtained for networks that cannot be modeled using traditional techniques.
Common-Ground-Type Tansformerless Inverters for Single-Phase Solar Photovoltaic Systems
DEFF Research Database (Denmark)
Siwakoti, Yam Prasad; Blaabjerg, Frede
2018-01-01
This paper proposes a family of novel flying capacitor transformerless inverters for single-phase photovoltaic (PV) systems. Each of the new topologies proposed is based on a flying capacitor principle and requires only four power switches and/or diodes, one capacitor, and a small filter at the o......This paper proposes a family of novel flying capacitor transformerless inverters for single-phase photovoltaic (PV) systems. Each of the new topologies proposed is based on a flying capacitor principle and requires only four power switches and/or diodes, one capacitor, and a small filter...
Challenges in thermal design of industrial single-phase power inverter
Directory of Open Access Journals (Sweden)
Ninković Predrag
2016-01-01
Full Text Available This paper presents the influence of thermal aspects in design process of an industrial single-phase inverter, choice of its topology and components. Stringent design inputs like very high overload level, demand for natural cooling and very wide input voltage range have made conventional circuit topology inappropriate therefore asking for alternative solution. Different power losses calculations in semiconductors are performed and compared, outlining the guidelines how to choose the final topology. Some recommendations in power magnetic components design are given. Based on the final project, a 20kVA single-phase inverter for thermal power plant supervisory and control system is designed and commissioned.
Sato, Tomoya; Ohnishi, Kouhei
The referential ZMP (Zero-Moment Point) trajectory that minimizes the variation of COG (Center of Gravity) velocity in the single support phase of a biped robot is shown. Two advantages of using this ZMP trajectory are discussed. The first advantage is that the variation of COG velocity is gradual. The second advantage is that the biped robot enables the heel-contact motion and the toe-off motion in the single support phase. The trajectory planning based on this ZMP trajectory is proposed. In simulation and experiment, the validity of the proposed method was confirmed.
Soft-Switched Neutral-Point-Clamped Single-Phase Boost Rectifier
Itoh, Ryozo; Ishizaka, Kouichi
A soft-switched neutral-point-clamped single-phase boost rectifier capable of compensating the imbalance load voltage is studied. This is based on a single-phase rectifier, in which an inductor is placed in series with the AC supply to resonate with a capacitor connected across the DC output of a full-bridge rectifier and the switching transition is mainly governed by a series resonance. The experimental prototype using insulated-gate bipolar transistors is implemented to investigate the operation under the charge control. The experimental results confirm that the rectifier has a neutral-point-clamp feature providing a good quality AC current.